Getting married in Las Vegas provides a large selection of wedding venues. One of the most beautiful country club is the Anthem Country Club, where we had an amazing time with our bride.
The Exquisite Private Golf Club surrounded by the majestic mountains of Las Vegas is an ideal site for weddings. It's located 15 minutes from the Las Vegas Strip, sparkling waterfalls, six lakes and picturesque canyons with beautiful panoramic views of the Las Vegas Strip.
This image was taken at the Anthem Country Club and was published on the Spectacular Bride Blog and also at the Spectacular Bride Magazine, what is an annual wedding magazine published by Bridal Spectacular Events, Inc. quarterly, featuring Las Vegas weddings.
Our beautiful bride is wearing a flowing chiffon ball gown with lace floral straps from Brilliant Bridal. Her sophisticated makeup and hair was created by Makeup in the 702 and her bouquet by Naakiti Floral.


Electromagnetic Geoservices ASA (EMGS) has received a signed contract from a repeat customer worth NOK 10 million (USD 1.7 million) for 3D EM data acquisition in the Barents Sea.
The Company expects to commence the survey in May, using the vessel BOA Thalassa.
EMGS uses its proprietary electromagnetic (EM) technology to support oil and gas companies in their search for offshore hydrocarbons. EMGS supports each stage in the workflow, from survey design and data acquisition to processing and interpretation. The company's services enable the integration of EM data with seismic and other geophysical and geological information to give explorationists a clearer and more complete understanding of the subsurface.
Posted on May 15, 2014 with tags 3D EM, Barents Sea, Boa Thalassa, contract, EMGS, europe, News by topic, seismic.


text:
In video engineering, field dominance refers to the choice of which field of an interlaced video signal is chosen as the point at which video edits or switches occur.

There are two main choices for field dominance: odd or even. With odd field dominance the edit or switch occurs at the start of the odd field. With even field dominance the edit or switch occurs at the start of the even field (some equipment, such as vision mixers or switchers allow the field dominance to be set to 'none' which means the switch will occur on the next field boundary after the switch has been pressed).

Interlacing divides the frame into two fields, each containing half the number of lines. Each field is scanned in 1/60 second under the 525-line system (or 480i – often incorrectly referred to as NTSC) or 1/50 of a second under the 625-line system (or 576i – often incorrectly referred to as PAL). With interlaced systems there are an odd number of lines in each frame. This means that there is a half line offset between the fields, therefore the lines in the second field will be positionally interleaved with the lines in the first field.

The lines are numbered in the order in which they are scanned (so it is incorrect to talk of the 'odd numbered lines' and the 'even numbered lines' when referring to interlaced video - but see PsF Line Numbers). In 525/60 systems, by convention, the first field in the frame is considered the even field. In 625/50 systems, by convention, the first field in the frame is considered the odd field.

Selecting a consistent field dominance in vision switching and linear editing systems will maintain color framing synchronization. Re-editing old video material already edited with a different field dominance convention can be problematic, as it can lead to "flash fields" when old and new edits are made too close together.

The term field dominance is often incorrectly used to refer to field order, particularly when referring to a field order error such as can occur when converting between certain different video file formats. Analogue 525/60 systems field one, line one starts when the falling edge of the first equalizing pulse is coincident with the start of a line. In 625/50 systems field one line one starts with line sync being coincident with the falling edge of the first broad pulse in the analogue field sync. Digital formats use a single-bit in their Timing Reference Sequence as the "Field" flag. Field flag bit F=0 marks the first field of each frame. F=1 Marks the second field.

PsF Line Numbers
In Progressive segmented frame (PsF), which is a way of sending a progressively scanned picture over an interlaced system, each alternate field will contain the odd and even lines of the original progressive scan. But once it is being carried as an interlaced picture the lines are numbered in the order they are being sent as with any 'normal' interlaced system.

See also
 Color framing

External links
 All About Video Fields
 Interlace, Interleave, and Field Dominance

Film and video technology
Video signal
Film and video terminology

redpajama_set_name: RedPajamaWikipedia


Following the ancient high-level route between Paro and Thimpu, the Druk Path is an excellent short trek, ideal for those who are in Bhutan only for a short duration.
You will experience the countryside, mountains, alpine meadows, glacial lakes and monasteries. The first day's walk leads to the ruined Jeli Dzong which sits on a high ridge above the Paro Valley and commands breathtaking views across to Chomolhari.
During the succeeding 4 days of trekking, we climb above the tree-line and cross several passes. En route, we camp beside clear mountain lakes, visit yak herders encampments and enjoy splendid panoramas of the peaks on the border with Tibet, including Jitchu Drake and Gangkar Puensum. We visit the ever impressive Taktsang Monastery in the Paro Valley and to visit the Tashichho dzong at Thimpu.
Day 01 - Arrival at Paro Airport. Overnight at hotel.
Day 02 - Day excursion from Paro to the Taktsang Monastery. Overnight at hotel.
Day 03 - Leave Paro trekking to Jele Dzong (Trek starts) Overnight at tented camp.
Day 04 - Trek from Jele Dzong to Jangchulakha. Overnight at tented camp.
Day 05 - Leave Jangchulakha and trek to Jimilang Tsho Overnight at tented camp.
Day 06 - Trek from Jimilang Tsho to Simkotra Overnight at tented camp.
Day 07 - Leaving Simkotra behind we trek through Phazoding onto Thimphu (finish trek) Overnight at hotel.
Day 08 - After a full day sightseeing in Thimphu we drive back to Paro. Overnight at hotel.
Day 09 - Transfer to international airport for your final departure.


text:
Lyft Teams Up With Dealers to Expand Its Driver Pool
Can Lyft and car dealers help each other out?
byStephen Edelstein| UPDATED Feb 7, 2018 9:14 AM
Stephen EdelsteinView stephen edelstein's Articles
SAEdelstein
As long as it continues using human drivers, Lyft will continue to rely on them to provide their own cars. That limits the pool of potential drivers to people who can already afford their own vehicle. Lyft is partnering with the National Independent Automobile Dealers Association to work around that.
Lyft will try to connect dealers with drivers who need cars, according to a company blog post. Dealers can sign up to become Lyft "referral partners" and earn money by referring new drivers to the ride-sharing company. The scheme will also allow drivers to apply money they earn driving for Lyft to the purchase of a car.
Customers who buy cars through participating dealers will get a bonus when they sign up to drive for Lyft, a company press release said. That bonus and any future Lyft earnings can be applied directly to the down payment and monthly car payments. In theory, drivers can literally pay off their cars by working for Lyft.
Dealers can also request Lyft rides for customers whose cars are in the shop. Depending on how reliable the service is, it could prove to be a cheaper alternative to maintaining large fleets of loaner cars. Dealers also won't have to worry about what will happen to said loaner cars while in customer hands.
The partnership between Lyft and the NIADA is interesting because it brings together a disruptive, buzzword-generating ride-sharing company and a fixture of the old-school automotive landscape.
While franchised dealerships probably aren't going anywhere, the battle between car dealers and Tesla over direct sales has shown that an alternative does exist, and reminded everyone that there is no love lost between car buyers and car dealers. Ride sharing also presents a threat to dealerships, because it could erode car sales. By partnering with Lyft, the NIADA is taking a step toward staying relevant in a changing world. At the same time, Lyft ensures people who want to drive can get cars.

redpajama_set_name: RedPajamaCommonCrawl


text:
Every Documentary Tells A Story
I've seen Arthur Miller — Writer, an intimate, not-uninteresting, years-in-the-making portrait of the late playwright. Scheduled to air on HBO next spring, the doc is a highly personal project by respected director Rebecca Miller, the playwright's daughter by his third wife. I've admired Miller and his plays all my life, but the doc acquainted me with a semi-intimate, unguarded version of him, which was new. Miller was a crusty, somewhat brusque fellow when it come to being interviewed — you could use the word "blunt" or even "craggy" — but he never seemed less than wise or perceptive.
Born in 1915, Arthur Miller led an interesting life as a fledgling writer from the mid '30s to mid '40s, but led a ferociously fascinating life when he began to produce important, critically respected plays. His big creative period began in '47 (All My Sons), peaked in '49 (Death of a Salesman), rumbled into the '50s (The Crucible, A View From The Bridge) and concluded with his last two big-league plays ('64's After The Fall and '68's The Price) — a little more than 20 years.
Miller's Marilyn Monroe period ('56 to '61) made him into a paparazzi figure, and also seemed to bring on the beginning of his creative decline. Miller and Monroe divorced in '61, and of course she died in August '62, an apparent suicide. Miller still "had it" for a few years after this period. After The Fall, a thinly disguised drama about his turbulent relationship with Monroe, opened in '64. Then came the less ambitious, more emotionally engaging The Price in '68.
It sounds unkind to note this, but from '68 until his death in '05 Miller was more or less treading water (trying but never getting there, working on his Roxbury farm, the great man who once was, writing less-than-great plays, writing travel books with his wife) and never managing the comeback that we all wanted to see.
A little more than half (maybe 60%) of Miller's doc covers her father's life from his birth to '68, or roughly 53 years. A little less than half covers the 37 years between The Price and his death in '05. I'm sorry to note this, but the film runs out of gas around the 60% mark just as Miller himself ran out of creative high-test gasoline in the late '60s. Arthur Miller — Writer is therefore half of an interesting documentary. I'm sorry if this sounds cruel, but the doc actually becomes a semi-downer once his life and work start to downshift. Your heart starts to slowly crack and break, watching the poor man go through this long, drawn-out, soul-draining, relatively infertile period.
November 8, 2017 6:03 pmby Jeffrey Wells
You're not allowed to talk about famous people looking different because of "work" they've had done. Well, you can, I suppose, but you might get knifed, punched and bitten by the same Twitter militants who pounced on Variety's Owen Gleiberman when he mentioned Renee Zellweger in June 2016, etc. But I'm allowed to talk about "work", you see, because I've undergone a Prague procedure or two. I'm therefore allowed to say whatever I want about this subject, and too bad if you don't like it. Here's my viewpoint: You can pay for a little physical refinement, but you really have to at least resemble the person you were when it's all over. That's all I'm going to say.
Great Openers
I haven't read Annette Insdorf's "Cinematic Overtures: How to Read Opening Scenes," but I can guess what's in it. I've always been more affected by great closing scenes, to be honest, but give me an hour or so and I can come up with several great opening scenes. Or great opening shots, for that matter. Like that baroque steambath shot in the beginning of Arthur Penn's Mickey One, for example.
What's my favorite opening scene or montage? The longish opener of Apocalypse Now is near the top of the list, followed by the dialogue-free beginning of Alfred Hitchcock's Rear Window, and then the eight-minute opening of Robert Altman's The Player. Right now I'm having trouble thinking beyond these three. No, I don't have a big sentimental thing about the beginning of John Ford's The Searchers.
How Oscar-Locked Is Gary Oldman?
A big swanky Academy screening of Joe Wright's Darkest Hour happens tonight, followed by a lobby party with the usual press and Academy types munching and schmoozing. But you know what the real occasion is, the real agenda? An official, communal acknowledgment that Gary Oldman is the most likely winner of the 2017 Best Actor Oscar.
Ever since Darkest Hour debuted in Telluride nine weeks ago conventional wisdom (i.e., the Gold Derby gang, those groovy Gurus) has been stating that Oldman's flamboyantly twitchy, broadly conceived performance as Winston Churchill — heavy latex, cigar, cane, bowler hat — is the one to beat.
Daniel Day-Lewis' late-arriving performance in Phantom Thread could result in a winning surge, especially given that Reynolds Woodcock is supposed to be DDL's swan-song performance. Some feel that Denzel Washington's brilliant-but-quirky-attorney performance in Dan Gilroy's Roman J. Israel is tied with Jake Gyllenhaal's Boston bombing victim in David Gordon Green's Stronger. Tom Hanks' turn as Washington Post editor Ben Bradlee in Steven Spielberg's The Post looks like a keeper, but Hanks has won twice before (Philadelphia, Forrest Gump). Considering his 21 years on the planet, Timothee Chalamet's expected Best Actor nomination for his Call Me By Your Name performance will be a triumph in itself.
I just can't see Oldman not winning. His Winston Churchill performance is broadly, at times hammily effective. There's the "we're sorry you lost the last time" factor with Oldman having nearly won six years ago for playing George Smiley in Tinker Tailor Solder Spy. And finally there's the "he's paid his dues and done great work for 30-plus years so it's time to finally give him the gold" thinking. It doesn't feel as if Oldman's breakout debut in Alex Cox's Sid and Nancy happened 31 years ago, agreed, but it's definitely been that long. Ronald Reagan was president then.
Should've Mentioned This Last Night…
A truly impressive one-sheet. The steps, one presumes, are an impressionistic rendition of the steps outside the U.S. Supreme Court building, where the New York Times & Washington Post vs. Nixon administration dispute over the Pentagon Papers was decided on 6.30.71. The size and steepness of the steps appear to have been exaggerated for dramatic effect.
The most exciting comment in yesterday's thread about the Post trailer was "Reverent and free" expressing relief that it appears to be "more [of] an ensemble thing than the Meryl Streep Show…they actually underplayed her in the trailer, giving her no big lines." A trailer rarely represents the film it's selling, but here's hoping that an "emphasis on ensemble' dynamic manifests in the film itself.
November 8, 2017 10:23 amby Jeffrey Wells


text:
Q: Desktop Wrappers for HTML5/JS Apps I am currently working on an HTML5/JS game, and I wanted to ask if there are any solutions to create EXE/App wrappers for the game to run the standalone.
I plan to use PhoneGap to get it on mobile devices, but I wanted to also release it for Windows/Mac/Linux as standalone games in their own window. Maybe if it turns out well enough, put it on Steam and Desura.
I hear Titanium Desktop is an option, but seems to be out of date or super buggy according to what I read in various posts. While others mention Adobe AIR, but I am not sure how well that will work, or if it will support all the JS I need.
So I need help with figuring out if there is a good solution for what I want to do.
Any information is helpful.

A: The BEST solution I found out there is NodeWebkit.
It's basically Google Chrome (actually Chromium) wrapped into a customizable chromeless interface. It uses Node.js as the backend (you can do data storing, interact with the system...), so you have the advantage of having the fast V8 javascript engine running on both ends.
As its core is just plain old Chromium, it will run smoothly anything that runs smoothly on Chrome.
Originally I suggested AppJS, but I think the project kind of went dead since then. NodeWebkit is very similar, but has an ever better approach: it brings the Node.JS API right into the client javascript, so everthing works seamlessly.

A: I've heard good things from http://www.appcelerator.com . I've also seen people use webkit. Or  use flex/as3/air, which has a built in webkit browser.
I've also heard of some custom html5 browsers that extend/improve the canvas element.

A: I recommend Electron for make desktop application wrapper, which has good docs and many community driven third party modules, examples and use cases: https://github.com/sindresorhus/awesome-electron.

redpajama_set_name: RedPajamaStackExchange


text:
\section{Introduction}

For almost thirty years it has been known that the velocity $v_s$ of
surface acoustic waves (SAWs) in piezoelectric crystals can be
effected by the electrical properties of nearby
conductors\cite{Inge1,Tseng}.  If the nearby conductors are
dissipative, then they can allow the SAW to attenuate also.  Work by
Ingebrigtsen\cite{Inge1}, and later authors\cite{Bier,Efros} showed
that when a piezoelectric is brought next to a thin layer of a
conducting medium, the SAW velocity shift $\Delta v_s$ and the
attenuation coefficient $\kappa$ satisfy the relation
\begin{equation}
  \label{eq:mastersaw}
  \frac{\Delta v_s}{v_s} - \frac{i \kappa}{q} = \frac{\alpha^2/2}{1 +
    i \sigma_{xx}(q,\omega)/\sigma_m}
\end{equation}
where $\sigma_{xx}(q,\omega)$ is the longitudinal conductivity of the
adjoining medium at wavevector $q$ and frequency $\omega = v_s q$.
Note that the velocity shift is measured with respect to the velocity
of the SAW when the adjoining medium has infinite conductivity.  The
coefficients $\sigma_m$ and $\alpha^2/2$ depend on material parameters
and are discussed at length in this paper.

Using the above relation between SAW velocity shift (or attenuation)
and the conductivity of a surface layer, experimentalists have probed
the conducting properties of two dimensional electron gases (2DEGs)
placed near the surface of crystals of
GaAs\cite{Weimann,Wixforth,Willett1,Willett2,Willett3,NewWillett,Others}.
(An approximation of the experimental geometry is shown in Fig. 1.)
In the earlier of these experiments\cite{Weimann,Wixforth}, the
wavelength of the probing SAW was much larger than the distance $d$
from the surface.  In this case, the depth $d$ can be neglected, and
the coefficients $\sigma_m$ and $\alpha^2/2$ can be assumed to be
constant.  However, in the more recent
experiments\cite{Willett2,Willett3,NewWillett,Willettcom}, the
wavevector $q$ can be so large that the product $qd$ is or order
unity.  In this case, one must carefully consider the wavevector
dependencies of these coefficients.  Roughly one might expect that the
coupling $\alpha^2/2$ should decay approximately as $e^{-2 q d}$.
However, it is seen experimentally that the coupling remains roughly
constant up to the highest wavevectors probed ($qd \approx 4$).  In
this paper, the wavevector dependences of $\sigma_m$ and $\alpha^2/2$
are explicitly derived for an experimental geometry similar to that
used in these experimental works.  Using the results derived here, it
should be possible to deduce quantitative results about the frequency
and wavevector dependent conductivities of the samples (A detailed
analysis of the data in References \onlinecite{Willett3} and
\onlinecite{NewWillett} is given in Reference \onlinecite{Simonwave}).

In References
\onlinecite{Weimann,Wixforth,Willett1,Willett2,Willett3,NewWillett,Willettcom},
the SAWs are propagated in the [011] direction along a (100) surface
of an (Al)GaAs crystal.  For most of this paper it will be sufficient
to approximate this system as the geometry shown in Fig. 1.  In other
words we assume that the 2DEG is a thin conducting layer a distance
$d$ (typically between 1000 and 5000 Angstroms) from the surface of a
homogeneous ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ crystal with the
fraction $x$ of Al taken to be approximately $30\%$.  The effects of
the differences between the actual experiments and this idealization
will be considered in the concluding section of this paper.

The outline of the remainder of this paper is as follows.  In section
\ref{sec:response}, the electromagnetic response function $K_{00}$ is
defined and related to the conductivity $\sigma_{xx}$.  The parameter
$\sigma_m$ is then defined in terms of the SAW velocity and the
effective dielectric constant (ie the effective strength of the
Coulomb interaction in the 2DEG).  The effective dielectric constant
is calculated explicitly in the appendix.  In section \ref{sec:diss} a
qualitative explanation is given as to how the SAW induces a potential
through piezoelectric coupling, thus resulting in an energy shift
and/or dissipation through the real and/or imaginary part of the
conductivity.  Equation \ref{eq:mastersaw} is then derived leaving
only the coupling constant $\alpha^2/2$ to be calculated.  In section
\ref{sec:details} the form of the SAW (neglecting the piezoelectric
coupling) is discussed with particular focus on finding the energy
density per unit area of the SAW.  The effect of a small piezoelectric
coupling is then considered in section \ref{sec:piezo} yielding a form
for the induced potential.  The coupling $\alpha^2/2$ is then derived
and is found to have a nontrivial and nonmonotonic dependence on $qd$.
Finally, section \ref{sec:conclusion} considers a number of
experimental issues and summarizes results.

\end{multicols}
\begin{figure}[htbp]
  \begin{center}
    \leavevmode
    \epsfxsize=5in
    \epsfbox{geom.eps}
  \end{center}
  {\centerline{\begin{minipage}[t]{5in} \small{Fig. 1: Model Geometry
        for Surface Acoustic Wave Experiments.  In the experiments the
        spacing $d$ is typically between 1000 and 5000 Angstroms.  The
        ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ typically has a
        fraction of Al given by $x\approx 30 \%.$}
      \end{minipage}}}
  \label{fig:geom}
\end{figure}
\begin{multicols}{2}

\section{Response Functions}
\label{sec:response}

The density-density response $K_{00}(q,\omega)$ is defined by the
relation
\begin{equation}
  \label{eq:Kdef}
  n(q,\omega) = K_{00}(q,\omega)
  \phi^{\mbox{\scriptsize{ext}}}(q,\omega)
\end{equation}
where $\phi^{\mbox{\scriptsize{ext}}}$ is the perturbing externally
applied scalar potential applied at a frequency $\omega$ and
wavevector ${\bf q} = q {\hat{\bf x}}$, and $n(q,\omega)$ is the
induced fluctuation density.  As we will see below, the SAW
experiments directly measure $K_{00}$ at finite frequency and
wavevector.

Many linear response measurements do not measure, however, the ratio
of induced density to the externally applied potential but rather the
response to the total potential.  A density $n({\bf q})$ induced by
the external vector potential, gives rise to a Coulomb scalar
potential
\begin{equation}
  \label{eq:vq}
  \phi^{\mbox{\scriptsize{ind}}}(q,\omega) = - v(q) n(q,\omega)
\label{coulomb}
\end{equation}
where $v(q) = \frac{2\pi}{{\epsilon_{\mbox{\tiny{eff}}}} q}$ is the
Fourier transform of the usual Coulomb interaction $ v(r) =
1/({\epsilon_{\mbox{\tiny{eff}}}} |r|)$.  (In principle, currents in
the sample give rise to an induced vector as well as scalar potential,
but in practice these fields are negligible).  Here
${\epsilon_{\mbox{\tiny{eff}}}}$ is the effective background
dielectric constant.  The wavevector dependent form of this dielectric
constant for the case of the model geometry of Fig. 1 is derived in
the appendix, and is given by
\begin{equation}
  \label{eq:eeff}
  \frac{{\epsilon_{\mbox{\tiny{eff}}}}}{\epsilon} = \frac{1}{2} \left(
  \frac{(\epsilon+\epsilon_0) \exp(qd)}{ \epsilon \cosh(qd) +
    \epsilon_0 \sinh(qd)} \right)
\end{equation}
where $\epsilon$ is the dielectric constant of the bulk
${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ and $\epsilon_0$ is the
dielectric constant of the medium above the surface ($\approx 1$).
The dielectric constant\cite{Optical} for
${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x\approx .3$ is
approximately 12.5 ( which is slightly lower than the dielectric
constant for GaAs which is approximately 13.0).

Using Eq. \ref{eq:vq}, the total scalar potential
\begin{equation}
  \phi^{\mbox{\scriptsize{tot}}} = \phi^{\mbox{\scriptsize{ext}}} +
  \phi^{\mbox{\scriptsize{ind}}}
\end{equation}
is now written as
\begin{equation}
  \label{eq:exttot}
  \phi^{\mbox{\scriptsize{tot}}} = ( 1 - v(q) K_{00})
  \phi^{\mbox{\scriptsize{ext}}}.
\end{equation}
It then becomes useful to define the polarization
$\Pi_{00}(q,\omega)$, which relates the induced density $n(q,\omega)$
to the total scalar potential via
\begin{equation}
  n(q, \omega) = \Pi_{00}(q, \omega)
  \phi^{\mbox{\scriptsize{tot}}}(q,\omega)
\end{equation}
Combining this definition with Eqs. \ref{eq:Kdef} and \ref{eq:exttot}
yields the  equation
\begin{equation}
  \label{eq:K00Pi00}
  [K_{00}]^{-1} = \left[\Pi_{00}\right]^{-1} + v(q).
\end{equation}
Since the response function $\Pi_{00}$ relates the density to the
total vector potential, it is useful to write this function in terms
of the conductivity $\sigma_{\alpha\beta}$ which relates the two
spatial components of the current $(j_x,j_y)$ to the two spatial
components of the total electric field $(E_x,E_y)$ via ${\bf j} =
\sigma {\bf E}$.  Using current conservation to give $j_x = (\omega
n/q)$, then yields
\begin{equation}
  \sigma_{xx} = \frac{-i \omega}{q^2} \Pi_{00}
\end{equation}
In particular, this allows us to write the general relation
\begin{equation}
  \label{eq:K00sigmaxx}
  [K_{00}]^{-1} =  v(q) - \frac{i \omega}{q^2 \sigma_{xx}}
\end{equation}
Throughout this work, we will assume that $\omega = v_s q$ with $v_s$
the SAW velocity, which then implies
\begin{equation}
  K_{00}(q,\omega) = \frac{{\epsilon_{\mbox{\tiny{eff}}}} q}{2 \pi(1 -
    i \sigma_{m}/\sigma_{xx}(q,\omega))}
\end{equation}
with
\begin{equation}
  \sigma_m = \frac{v_s {\epsilon_{\mbox{\tiny{eff}}}}}{2 \pi}.
\end{equation}
The function $\sigma_m(qd)$ is shown in Fig. 2.  Here, the
experimentally relevant parameters for References
\onlinecite{Willett3} and \onlinecite{NewWillett} are used.  These are
$\epsilon = 12.5$ and $v_s = 3010 m/sec$ (see section
\ref{sec:details} below).

\section{Induced Energy Shift}
\label{sec:diss}

Due to the piezoelectric coupling, an external scalar potential
$\phi^{\mbox{\scriptsize{ext}}}$ is induced in the 2DEG.  For now, we
will write
\begin{equation}
  \label{eq:aex}
  \phi^{\mbox{\scriptsize{ext}}} =  C e_{14} F(qd)/\epsilon
\end{equation}
where $C$ is the amplitude of the SAW, $e_{14}$ the piezoelectric
stress constant, and $F$ is a dimensionless function of $qd$ that
represents the fact that the SAW decays into the bulk.  Clearly $F$
should approach a constant as $qd \rightarrow 0$ and should approach
zero as $qd \rightarrow \infty$.  Roughly, one should expect that the
function $F$ should decay as $e^{-qd}$.

The induced energy density per unit area due to this external
potential is given by
\begin{equation}
  \delta U = \frac{1}{2} K_{00} |\phi^{\mbox{\scriptsize{ext}}}|^2
\end{equation}
This expression is obtained from integrating a differential $d \delta
U = n(\phi^{\mbox{\scriptsize{ext}}}) d
\phi^{\mbox{\scriptsize{ext}}}$ and using Eq. \ref{eq:Kdef}. (Note
that using $\phi^{\mbox{\scriptsize{tot}}}$ here instead would account
for only the electrical energy).  Using Eq. \ref{eq:K00sigmaxx} we can
rewrite this shift as
\begin{equation}
  \delta U = \frac{{\epsilon_{\mbox{\tiny{eff}}}} q}{4 \pi (1 - i
    \sigma_{m}/\sigma_{xx}(q,\omega))}
  |\phi^{\mbox{\scriptsize{ext}}}|^2
\end{equation}
We now want to measure this energy shift with respect to the shift for
$\sigma_{xx} \rightarrow \infty$.  Thus,
\begin{eqnarray}
  \Delta U &\equiv& \delta U - \delta U(\sigma_{xx} = \infty) \\ &=&
  \frac{{\epsilon_{\mbox{\tiny{eff}}}} q}{4 \pi } \left[ \frac{1}{1 -
    i \sigma_{m}/\sigma_{xx}(q,\omega)} - 1 \right]
  |\phi^{\mbox{\scriptsize{ext}}}|^2 \\ & = &
  \frac{{\epsilon_{\mbox{\tiny{eff}}}} q}{4 \pi } \left[ \frac{1}{1 +
    i \sigma_{xx}(q,\omega)/\sigma_m } \right]
  |\phi^{\mbox{\scriptsize{ext}}}|^2
\end{eqnarray}

It is found below that the surface acoustic wave has an energy density
proportional to $C^2 q^2$ where $C$ is the amplitude of the wave and
$q$ is the wavevector.  Furthermore, the wave decays exponentially
into the bulk with a decay constant proportional to $q$.  Thus, when
integrated in the ${\hat{\bf z}}$ direction, the energy $U$ per unit
surface area is given by
\begin{equation}
  \label{eq:energyden}
  U = q C^2 H
\end{equation}
where $H$ is a factor that depends on material parameters that we will
determine below.  Combining this with the results of the above
section, the fractional energy shift is then given by
\begin{equation}
  \frac{\Delta U}{U} =
  \frac{\alpha^2/2}{1 + i \sigma_{xx}(q,\omega)/\sigma_m }
\end{equation}
where
\begin{equation}
  \label{eq:msalph}
  \frac{\alpha^2}{2} = \frac{{\epsilon_{\mbox{\tiny{eff}}}}}{\epsilon}
  \frac{e_{14}^2 }{4 \pi \epsilon H} |F(qd)|^2
\end{equation}
(Note that the factor of $4 \pi$ will vanish when
${\epsilon_{\mbox{\tiny{eff}}}}$ is converted into MKSI units).
Clearly, this result implies the velocity shift and attenuation
relation given by Eq.  \ref{eq:mastersaw}.  All that now remains is the
tedious job of evaluating the constant $H$ as well as the functional
form $F$.  It should be noted that in the small $qd$ limit, various
experiments\cite{Grudowski,Weimann,Wixforth,Willett1,Willett2,Willett3}
have measured the value of the coupling constant and have found
$\alpha^2/2 \approx 3.2 \times 10^{-4}$.  As is discussed below in
section \ref{sec:conclusion}, these measurements should be viewed with
caution.  As discussed above, one expects roughly that $F$ decays as
$e^{-qd}$ so that $\alpha^2/2$ decays as $e^{-2 qd}$.  This, however,
contradicts experimental observation\cite{Willettcom}.  Below, in a
more careful analysis, we will see why the decay is actually somewhat
slower and shows a nonmonotonic dependence on $qd$.

\section{Non-Piezoelectric SAWs}
\label{sec:details}

We begin by discussing the solution of the SAW equations with the
piezoelectric coupling set to zero.  The piezoelectric coupling will
then be added at lowest order.

Defining a displacement vector $u_k$, the elastic wave equation is
given by\cite{Landau,Farnell,Auld}
\begin{equation}
  \label{eq:waveeq}
  c_{ijkl} \partial_l \partial_i u_k + \rho \ddot u_j = 0
\end{equation}
where $\rho$ is the mass density, $c$ is the elastic tensor, we have
used the notations $\partial_l f= \frac{\partial f}{\partial x_l}$, ,
$\dot{f} = \frac{\partial f}{\partial t}$, and repeated indices are
summed. For GaAs, AlAs, and other crystals of cubic symmetry there are
only 3 independent elastic constants.  These constants are
conventionally called $c_{11}$, $c_{12}$, and $c_{44}$.  For GaAs at
low temperatures, the elastic constants $c_{11}$, $c_{12}$, and
$c_{44}$ are given by\cite{Handbook} $12.26 \times 10^{10}, 5.71
\times 10^{10}$, and $6.00 \times 10^{10} N/m^2$ respectively.  The
constants for AlAs\cite{Handbook,Chetty} are given approximately by
$12.2 \times 10^{10}, 5.5 \times 10^{10}$, and $5.7 \times 10^{10}
N/m^2$ respectively.  It is noted that the elastic constants of the
two materials are roughly the same.  For
${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ it is reasonable to
interpolate for any value of $x$.  (Experimentally, there may be some
uncertainty in $x$).  The density\cite{Handbook} of GaAs is 5307
$kg/m^3$, and the density of AlAs is 3598 $kg/m^3$.  Thus for
${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x \approx .3$, the
density interpolates to approximately 4794 $kg/m^3$, which differs
from that of GaAs by only 10\%.

In considering surface waves, the wave equation must be supplemented
with the boundary condition at the free surface that there is no total
force at the surface.  This condition is written
as\cite{Landau,Farnell}
\begin{equation}
\label{eq:boundary}
c_{{\hat{\bf z}}jkl} \partial_l u_k = 0.
\end{equation}
where the subscript ${\hat{\bf z}}$ represents the direction normal to
the surface.  For certain geometries, analytic solutions of the SAW
equations are available.  In the present case of a (100) surface with
wave propagation in the [011] direction, the velocity of SAW
propagation is given by the solution (here we are interested in the
lowest velocity solution) of the cubic equation\cite{Stonely}.
\begin{equation}
  \left( 1 - \frac{c_{11}}{c_{44}} X \right)\left( \frac{c_{11}
      c_{11}' - c_{12}^2}{c_{11}^2} - X \right)^2 = X^2 \left(
    \frac{c_{11}'}{c_{11}} - X \right)
\end{equation}
where $c_{11}' = \frac{1}{2} ( c_{11} + c_{12} + 2 c_{44})$ and $X =
\rho v_s^2/c_{11}$ gives the SAW velocity $v_s$.

For ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x \approx .3$, the
velocity is approximately 3010 m/sec.  (This differs from that of pure
GaAs by only 5\%.)  Once the velocity is determined, one can easily
solve analytically for the form of the SAW.  For the experimental
geometry we are presently considering, the displacements for this wave
can be written as\cite{Stonely,endnote2}
\begin{eqnarray}
  \label{eq:uform}
  u_x &=& C \left(e^{-\Omega q z - i  \varphi} + e^{-\Omega^* q z + i
    \varphi} \right) e^{iq (x - v_s t)}
\\i  u_z &=& C \left(\gamma e^{-\Omega q z - i  \varphi} + \gamma^*
e^{-\Omega^* q z + i  \varphi} \right) e^{iq (x- v_s t)}
\end{eqnarray}
with $u_y = 0$ and $C$ the amplitude ($C$ has dimensions of length).
Here, the ${\hat{\bf x}}$ direction is chosen in the direction of wave
propagation (the [011] direction).  The parameters $\Omega, \gamma$,
and $\varphi$ are determined by\cite{Stonely,endnote2}
\begin{eqnarray} \nonumber
  0 &=& (c_{11}' - X c_{11} - \Omega^2 c_{11})(c_{44} - X c_{11} -
  \Omega^2 c_{44})\\ & & ~~~~~~~~~~~~~~ + \Omega^2 (c_{12} + c_{44})^2
 \\ \gamma &=& \Omega  \label{eq:Omegaroot}
 \left[ \frac{c_{12} + c_{44}}{c_{44} - (X + \Omega^2) c_{11}}\right]
    \\ e^{-2 i \varphi} &=& - \frac{\gamma^* - \Omega^*}{\gamma - \Omega}
\end{eqnarray}
In the case of ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x = .3$, the values of $\gamma$ and
$\Omega$ and $\varphi$ are given in this case by $\Omega \approx .501
+ .472 i$, $\gamma \approx -.705 + 1.146i$, and $\phi \approx 1.06$.

The local energy density of this wave can be written
as\cite{Landau,Auld}
\begin{equation}
  E = \frac{1}{2} c_{ijkl} u_{ij} u_{kl}^*
\end{equation}
where the strain $u_{ij}$ is given by
\begin{equation}
  u_{ij} = \frac{1}{2} (\partial_i u_j + \partial_j u_i)
\end{equation}
For the AlGaAs surface wave discussed above, the energy density can be
written as\cite{Auld}
\begin{eqnarray}
  \label{eq:eden2} \nonumber
  E &=& \frac{1}{2} \left( c_{11}' |u_{xx}|^2 + c_{11} |u_{zz}|^2
\right. \\  & & ~~~~~~~~~~ \left. +2 c_{12} Re[u_{xx}^* u_{zz}] + c_{44} |2
u_{xz}|^2 \right)
\end{eqnarray}
Inserting the above described form of the wave, yields the strains
\begin{eqnarray}
  u_{xx} &=&  i q u_x
  \\
  u_{zz} &=& i q C \left( \gamma \Omega e^{-\Omega q z - i \varphi} +
  \mbox{c.c.} \right)e^{iq(x - v_s t)} \\ 2  u_{xz} &=& C q \left(
  [\gamma - \Omega] e^{-\Omega q z - i \varphi} + \mbox{c.c.}
\right)e^{iq(x - v_s t)}
\end{eqnarray}
with ``c.c.'' meaning complex conjugate.  Finally, integrating the result
of Eq.  \ref{eq:eden2} in the ${\hat{\bf z}}$ direction yields an energy per
unit surface area in the form given by Eq.  \ref{eq:energyden} with
\begin{eqnarray}
  \nonumber H &=& \mbox{Re} \left[ c_{11}' \left( \frac{e^{-2 i
      \varphi}}{\Omega} + \frac{1}{\alpha} \right) \right. \\
  \nonumber &+& c_{11} \left( \frac{(\gamma - \Omega)^2 e^{-2 i
      \varphi}}{\Omega} + \frac{|\gamma - \Omega|^2}{\alpha} \right )
  \\ \nonumber &+& c_{44} \left( (\gamma^2 \Omega) e^{- 2 i \varphi}+
  \frac{|\gamma \Omega|^2}{\alpha} \right ) \\ &+& \left. 2 c_{12}
  \left( \gamma e^{-2 i \varphi} + \frac{\mbox{Re}(\gamma
      \Omega)}{\alpha} \right) \right]
\end{eqnarray}
where $\alpha = \mbox{Re}(\Omega)$.  This yields a numerical value of
\begin{equation}
H \approx 28.8 \times 10^{10} N/m^2
\end{equation}
(The value for pure GaAs is lower by only about 2 \%).

\section{Piezoelectric Coupling}
\label{sec:piezo}

When a piezoelectric coupling is added, the wave equations take the
form\cite{Inge1,Farnell,Auld}
\begin{eqnarray}
  \label{eq:waveeq2}
  c_{ijkl} \partial_l \partial_i u_k + e_{kij} \partial_k \partial_i
  \phi + \rho \ddot u_j &=& 0 \\
  e_{ikl} \partial_l \partial_i u_k - \epsilon \nabla^2 \phi = 0
  \label{eq:Poisson}
\end{eqnarray}
where $e$ is the piezoelectric stress tensor, $\phi$ is the electric
potential, and $\epsilon$ is the dielectric constant of the medium
(here $\epsilon$ is assumed to be isotropic).  For GaAs, AlAs (and
other cubic crystals of class $\bar{4}3m$), there is only one
independent nonzero component of the piezoelectric tensor\cite{Auld}
called $e_{14}$.

The value of $e_{14}$ for GaAs has an accepted
value\cite{Handbook,Auld} of approximately .157 $C/m^2$.  However, it
should be noted that there is a small amount of evidence\cite{Smaller}
that the actual value might be somewhat lower (by perhaps as much as
40\%).  For the present work we will choose to work with the accepted
value.  For the case of AlAs, it is even more difficult to find a
reliable value for the piezoelectric coupling.  To the author's
knowledge, no reliable measurement of this quantity has been made to
date\cite{IIIV}.  Several calculations of $e_{14}$ have been made, and
the results range from\cite{Gironcoli} as small as .02 $C/m^2$
to\cite{Hubner} as large as .22 $C/m^2$.  If we choose one of these
for the value of $e_{14}$ for AlAs and interpolate to obtain $e_{14}$
for ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x = .3$ (linear
interpolation is thought to be roughly correct\cite{IIIV}) we will
obtain results that range from approximately .11 $C/m^2$ to .18
$C/m^2$.  Since since $e_{14}$ is squared in the final result (Eq.
\ref{eq:msalph}), these uncertainties will be magnified.  Although
this uncertainty results in an overall change in the magnitude of the
coupling, it will not change the functional form of the coupling with
respect to changes in $qd$.  For definiteness, we will choose to work
with a value of $e_{14}$ of .145 $C/m^2$ for
${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x \approx .3$, (which is
close to the value for pure GaAs).  The uncertainty is approximately
.04 $C/m^2$.  When this quantity is squared in Eq. \ref{eq:msalph},
the final result has an uncertainty in scale of about 50\%.

Since the piezoelectric coupling $e_{14}$ is small, it is
clear from the second equation that $\phi$ will be order $e_{14}$
smaller than $u$.  Thus, the first equation will be solved by the
nonpiezoelectric solution discussed above with corrections only at
order $e_{14}^2$.  The mechanical boundary conditions in the
piezoelectric case are\cite{Inge1,Farnell}
\begin{equation}
\label{eq:boundary2}
c_{{\hat{\bf z}}jkl} \partial_l u_k + e_{k{\hat{\bf z}} j} \partial_k \phi = 0.
\end{equation}
Again, this will be satisfied by the nonpiezoelectric solution with
corrections at order $e_{14}^2$.  The electrical boundary condition
that the normal component of electric displacement ${\bf D}$ is
continuous across the surface can be written as\cite{Inge1}
\begin{eqnarray}
  \phi &=& i \frac{v_s^2}{\omega} Z D_{{\hat{\bf z}}} \\ D_{{\hat{\bf z}}} &=&
  e_{{\hat{\bf z}}kl} \partial_l u_k - \epsilon \partial_k \phi
\end{eqnarray}
Where $Z$ is the transverse magnetic wave impedance ($Z = E_x/H_y$) of
the medium above the surface.  The impedance of the adjoining medium
can be written as
\begin{equation}
Z = \frac{i}{v_s \epsilon_0}
\end{equation}
where $\epsilon_0$ is the adjoining medium's dielectric constant.
These conditions can be rewritten as
\begin{equation}
  \label{eq:boundary3}
  \left. 0 = \left(\epsilon_0 q \phi +
e_{{\hat{\bf z}}kl} \partial_l u_k - \epsilon
  \partial_{{\hat{\bf z}}} \phi \right) \right|_{z=0}
\end{equation}
Here, this boundary condition must be properly treated since it is of
lower order in $e_{14}$.  Thus, we will use the above nonpiezoelectric
solution for $u$ and solve Eqs.  \ref{eq:Poisson} and
\ref{eq:boundary3} for $\phi$.  These two equations in our case can be
recast as
\begin{eqnarray}
  \epsilon \nabla^2 \phi &=& e_{14} (\partial_z u_{xx} + 2 \partial_x
  u_{xz}) \label{eq:Poisson2} \\
  0 &=& \left. \left(\epsilon_0 q \phi + e_{14} u_{xx} -
  \epsilon
  \partial_{{\hat{\bf z}}} \phi \right) \right|_{z=0} \label{eq:boundary4}
\end{eqnarray}

The proposed form of solution is
\begin{eqnarray}
  \nonumber \phi &=& \frac{i C e_{14}}{\epsilon} e^{i q ( x - v_s t) }
  \left[ A_1 e^{- \Omega q z -i \varphi} \right. \\ & & ~~~~~~~~~~~~
    \left. + A_2 e^{-\Omega^* q z + i \varphi} + A_3 e^{-q z} \right]
  \label{eq:phiform}
\end{eqnarray}
with $C$ the amplitude of the SAW.  Eq. \ref{eq:Poisson2} immediately
yields the conditions
\begin{equation}
  A_1 = A_2^* =  \frac{\gamma - 2 \Omega}{\Omega^2 - 1}
\end{equation}
Finally, using Eq.\ref{eq:boundary4} yields
\begin{equation}
  A_3 = \frac{- 2}{1+r} \left[\cos \varphi + r \mbox{Re}(A_1 e^{-i
    \varphi}) + \mbox{Re}(\Omega A_1 e^{-i \varphi}) \right]
\end{equation}
with $r = \epsilon_0/\epsilon \approx \frac{1}{12.5}$.

\begin{figure}[htbp]
  \begin{center}
    \leavevmode
    \epsfxsize=3.0in
    \epsfbox{elastic.eps}
  \end{center}
  {\centerline{\begin{minipage}[t]{3in} \small{Fig. 2: Coupling
        Constants as a function of $qd$ with $q$ the wavevector and
        $d$ the distance from the 2DEG to the surface.  Top:
        $\sigma_m(qd)$ in units of inverse Ohms.  In this calculation,
        the dielectric constant of the medium
        (${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$) is taken to be 12.5.
        Bottom: $\alpha^2(qd)/2$ (dimensionless).  Here, the
        piezoelectric constant is taken as .145 $C/m^2$.  The
        uncertainty in this number results in an uncertainty in the
        scale of approximately $50\%$.  Note that at $qd = 0$ the
        coupling constant is roughly $3.7 \times 10^{-4}$  in good
        agreement with experiment.  }
      \end{minipage}}}
  \label{fig:alpha}
\end{figure}

Once the potential $\phi$ has been determined, this potential is then
treated as the external potential $\phi^{\mbox{\scriptsize{ext}}}$
applied to the 2DEG.  Note that the scalar potential
$\phi^{\mbox{\scriptsize{ind}}}$ then induced by the density
fluctuations in the 2DEG does not change the solution to Eqs
\ref{eq:Poisson} and \ref{eq:boundary3} above since $\nabla^2
\phi^{\mbox{\scriptsize{ind}}} = 0$ everywhere outside of the 2DEG and
$\epsilon_0 q \phi^{\mbox{\scriptsize{ind}}} = \epsilon
  \partial_{{\hat{\bf z}}} \phi^{\mbox{\scriptsize{ind}}} $
  at the surface (the solution of such a boundary condition is
  discussed in the appendix).  The form of the potential is given by
  Eq. \ref{eq:aex} where the functional dependence $F$ is given by
\begin{equation}
  F(qd) = 2 |A_1| e^{-\alpha q d} \cos(\beta q z + \phi + \xi) + A_3 e^{-q d}
\end{equation}
where $\Omega = \alpha + \beta i$ and $A_1 = |A_1| e^{-i \xi}$.  Here
we have the values $|A_1| \approx 1.59 $, $\phi + \xi \approx 2.41$,
$A_3 \approx -3.10 $.  Using these values in Eq. \ref{eq:msalph}
yields a the coupling constant $\alpha^2/2$.  The functional
dependence of $\alpha^2/2$ on $qd$ is shown in Fig. \ref{fig:alpha}.
It is clear that the dependence is quite nontrivial.  First of all,
the exponential decay at large $qd$ is roughly proportional to
$e^{-qd}$ rather than $e^{-2qd}$.  This is because, due to the precise
material parameters, the SAW decays into the bulk as $e^{-\alpha q d}$
with $\alpha \approx \frac{1}{2}$.  More importantly, at small $qd$
the coupling seems to oscillate.  The reason for this is roughly that
the boundary condition fixes the strain $u_{xz}$ to be zero at $z =
0$.  Thus $E_{x}(z=0)$ is mainly caused by the surface charge (ie, the
$A_3$ term in Eq. \ref{eq:phiform}).  As $z$ (or $d$) increases, the
effect of the surface charge term quickly decays, but the strain
$u_{xz}$ becomes nonzero so that the coupling decays first, but then
increases.  Finally, at large $qd$, the exponential decay of the SAW
damps out the coupling.

\section{Conclusion and Further Considerations}
\label{sec:conclusion}

This work has focused on surface acoustic waves in AlGaAs coupled to a
2DEG a distance $d$ away from the surface of the sample.  The general
relation (Eq.  \ref{eq:mastersaw}) between the fractional SAW velocity
shift $\Delta v_s/v_s$, the attenuation $\kappa$ and the conductivity
$\sigma_{xx}$ of the 2DEG was derived, and the coefficients
$\alpha^2/2$ and $\sigma_m$ were explicitly calculated as a function
of the product $qd$ of the wavevector $q$ and the distance $d$ to the
surface.

Although Eq. \ref{eq:mastersaw} is very general, the values of the
coefficients $\sigma_m$ and $\alpha^2/2$ are quite dependent on
material parameters.  As discussed in the text and in the appendix,
$\sigma_m$ is dependent only on the velocity of the SAW and on the
effective background dielectric constant in the 2DEG (which is in
general wavevector dependent).  The coupling constant $\alpha^2/2$, on
the other hand, is very sensitive to the details of the sample.  In
this paper we have focused only on a relatively simple model geometry
where the sample is assumed to be a homogeneous slab of AlGaAs to
simplify the solution of the wave problem.  In actual experiments, the
samples are often complicated many layer heterostructures.  In the
relevant experiments\cite{Willettcom}, the bulk of the crystal (below
the 2DEG) is pure GaAs and {\it most} of the crystal between the 2DEG
and the surface is ${\mbox{Al}_x\mbox{Ga}_{1-x}\mbox{As}}$ with $x
\approx .3$.  However, additional thin layers of GaAs are added in
this region, along with Si dopants.  In principle, we could solve the
wave equations for this complicated geometry and apply similar
methods, but in practice such problems can only be solved numerically.
However, since the elastic constants, densities, and dielectric
constants of AlGaAs and GaAs are so similar we suspect that these
heterostructures can be well approximated by the homogeneous system
discussed here.

In using Eq. \ref{eq:mastersaw} to extract $\sigma_{xx}(q,\omega)$
from experimental data, there are several complications.  To begin
with, accurate measurements of the attenuation are extremely
difficult, as are absolute measurements of the
velocity\cite{Willettcom}.  However, measurements of the relative
velocity shift can be made quite accurately.  Another complication is
that the above formula for the velocity shift (Eq.
\ref{eq:mastersaw}) gives the velocity shift $\Delta v_s$ relative to
the velocity of the SAW if the conductivity of the 2DEG were infinite.
In practice, the velocity shift is usually measured relative to the
velocity of the SAW at zero magnetic field.  It is often the case in
high mobility samples (particularly at low frequency) that the
conductivity at zero magnetic field is sufficiently large that it can
be considered infinite and this approximation becomes reasonable.
However, more generally, if the conductivity at zero field is well
known, the resulting measured shift can be appropriately adjusted.

In References
\onlinecite{Weimann,Wixforth,Willett1,Willett2,Willett3,NewWillett},
the parameters $\sigma_m$ and $\alpha^2/2$ are both fit to experiment.
To do this, the dc conductivity is measured and put into Eq.
\ref{eq:mastersaw}, the values of $\sigma_m$ and $\alpha^2/2$ are then
varied until a good fit is obtained to the experimentally measured
values of $\Delta v_s/v_s$ as a function of magnetic field.  There are
several possible problems with this procedure.  To begin with, the
zero frequency (dc) conductivity is expected to be somewhat different
from the finite frequency and wavevector conductivity
$\sigma_{xx}(q,\omega = v_s q)$ that must be used in Eq.
\ref{eq:mastersaw}.  Furthermore, there are indications that due to
large scale inhomogeneities in the sample\cite{Simonnet}, the measured
dc conductivity may not accurately represent the spatial average of
$\sigma_{xx}$.  We thus conclude that these experimental fits of these
parameters to the dc conductivity should be viewed with caution.
Nonetheless the qualitative features of these experiments are
relatively robust and many of the conclusions drawn from these
experiments are relatively independent\cite{Willett2,Willett3} of the
precise value of the fit parameters $\sigma_m$ and $\alpha^2/2$.  A
more careful quantitative analysis of these data is given in Reference
\onlinecite{Simonwave}.

\vspace*{10pt} \centerline{ACKNOWLEDGMENTS} \vspace*{10pt}

It is a pleasure to acknowledge helpful discussions with Bertrand
Halperin, Bob Willett, Eric Westerberg, and Konstantin Matveev.  The
author is also grateful to G. W. Farnell for sending computer code for
numerically analyzing more complicated SAW problems.  This work is
supported by the National Science Foundation under grant numbers
DMR-94-16910 and DMR-95-23361.

redpajama_set_name: RedPajamaArXiv


text:
Awkward with Alexandra Petri
Washington Post columnist Alexandra Petri is the queen of awkwardness. She didn't audition for "America's Next Top Model" and become a yodeling champion without a high tolerance for the sound of people laughing. And, as it turns out, building up your ability to embrace awkwardness can be a kind of superpower during difficult times… if you know how to use it.
Alexandra Petri
Alexandra Petri is a humorist and writer for the Washington Post. She is the author of the book A Field Guide to Awkward Silences and a former contestant on Jeopardy! She has extensive knowledge on many topics, but none greater than her knowledge of puns.
Discussion questions for this podcast episode available here.
To learn more about A Field Guide to Awkward Silences by Alexandra Petri, click here.
Follow Alexandra on Instagram, Twitter, and her Washington Post column.
Read the full audio transcript.
[Kate Bowler] This is Everything Happens. I'm Kate Bowler. For those of you who've been with me from the beginning, you know that I've been living through my own dark time, after I was diagnosed with stage 4 cancer. And when you have a serious illness one thing you are definitely going to learn about is awkwardness.
After I was diagnosed, people didn't know how to respond. Human beings are, by nature, ridiculous. And let's face it, nothing is more ridiculous than having to answer the question, "How are you?" in a casual way after you've been diagnosed. So I thought it would be useful to talk to an expert in awkwardness.
My guest today is Alexandra Petri, and she is easily the most fun person on the planet to introduce. She not only writes a hilarious and clever column for The Washington Post, but she has auditioned for "America's Next Top Model" and performed more than adequately in an international whistling convention. She once joined a cult, "to be polite". She is the author of "A Field Guide to Awkward Silences" and has agreed to allow me to be awkward with her today. I'm so glad you're here.
[Alexandra Petri] Thank you so much for having me.
So, Alexandra, do you mind if I uncomfortably read the opening passage of your own book to you, the author? Because of that Super Cool Introduction no one is going to believe that you are awkward.
[AP] Oh, go for it! It'll be very awkward, but I think that's what we're going for.
[KB] Thank you. This is my favorite. "I am afraid of many things: drowning, fire, the disapproval of strangers on the Internet, that I'll be hit by a bus without having had a chance to clear my browser history. You know, the usuals. One thing I'm not afraid of? Looking like an idiot." To me, that seems like a kind of superpower. Does it feel like that sometimes?
[AP] It really does, because I think … recently, I've been watching "Trial & Error," and there's one character that can't feel his hand at all, so he's able to, like, cook and put his hand on stoves and stuff. And it's like, you should feel that – if your hand were in good shape, you wouldn't be putting it on a stove. But he's able to do so much more with that hand while cooking, and I sort of feel the same way. I think Ogden Nash said, "How could anyone do anything immortal when they see they look funny doing it and have to stop to chortle?" I certainly don't notice how weird I look at any given time. Although increasingly as an adult, I'm like, "Oh, in retrospect, I see how that would have been bad, but…."
[KB] I have to say my favorite example, though, from your book, is the time that you asked to participate in a dog show as a human.
[AP] Oh, well the previous year had gone to a cat show. And I was cheering on and I thought they didn't have enough spirit for the cats. There was a cat named Mojo, and I was like, "Mojo! Mojo!" And then they were like, "Could you please save this for after the ceremony?" So the next year they didn't have the cat show that weekend. They had a dog show, and I'm like, "Well, I'm going o get people to go to this dog show, and we're going to have a good time." And I get there and I look down and there's this beautiful dog agility course just laid out there
[KB] Begging to be…
[AP] And I'm thinking this is really fun. Oh yeah. So I go up to the organizer, and I'm like, "Excuse me, I promised my dead dog Topanga that I would do something special for her at a dog show. Do you mind if I run the course in her honor?" And I should mention that this whole time, we've been riding around on like mopeds, and so I had a helmet because I'd been riding a moped. So what this organizer saw was this strange woman in a helmet who comes up and says, "Excuse me, I'd like to run your course in honor of a dog named Topanga." And so I think she was like, "Well, we're just going to do whatever this person wants." So they clear the dogs off, and they let me run it. And I ran – it was really difficult to run, honestly. The dogs are much smaller and more agile than I am. And I was like, "Topanga! Topanga!" And at the end, she goes, "I hope that was therapeutic for you."
[KB]Now please leave, woman in a helmet.
[AP] Goodbye forever please.
[KB] When people get sick, they often create these bucket lists, and then they want to check things off. And one of the things I really love about your approach to writing, and I think life, is that you kind of do that anyway. Like, you're not waiting to get sick to start collecting experiences. It's like one of the first things you say in your book, which I also wrote down and will read back to you awkwardly now: "I collected experiences the way some people collect old coins or commemorative stamps." So what drives you to collect experiences, do you think?
[AP] Part of it is, I just really want to get the most out of my time around here. And I think having more different experiences makes you a more interesting person. Because all the people I know who I think are fascinating have like gone and done the thing that scared them and they've gone and traveled, or they've worked in an interesting field, or they've built a gigantic sculpture using only salt and pepper shakers. Like, they've really done the thing. And so I wanted to do as much of the thing as possible because I know eventually you get to sit in a rocking chair and just reminisce. So I would hate to have not done a bunch of stuff before that time occurs, whenever that time is.
[KB] So what are some experiences that you've been able to have because you weren't afraid?
[AP] Well I think a lot of it is, I really love getting to meet people in the world where they feel most themselves. One of the neat things about both journalism in general and my personal hobbies and interests is I like to go to gatherings of folk who, once a year, they get to sort of become their truest self. So they'll be reenacting the Civil War or reenacting Star Wars, which I guess you can reenact. It didn't happen, but you can reenact it. And things like that and sort of go into worlds like that.
I would go to a Star Wars convention and just like wear a Jabba the Hutt suit and hang out, and that's the one part where you feel sexier as Jabba the Hutt than you do when you remove the costume. Like you're on a Disney ride, and this guy behind me … I took off the Jabba the Hutt inflatable head so that I could see. And he goes, "Wow, way to ruin the illusion!" And I'm like, "Yeah, you believed I was Jabba the Hutt."
[KB] You tell this incredible story in your book of when you started this amazing experiment where you decided to teach yourself to fail in bigger and more spectacular ways. Can you tell us some of the failures that you attempted?
[AP] Oh sure. Growing up watching like "America's Most Wanted," a, and "Got Talent," b, and "American Idol," c, I quickly realized, well, I'm not going to be able to catapult myself to fame through sheer excellence. I need to figure out something that I can do. And then I saw William Hung. And I thought, "Oh, this man is so good. Like he has this amazing joyful presence."
[KB] And for those of you that don't remember William Hung, please just allow everyone to revisit for a moment.
[AP] He was one of those — everyone watched the first few weeks of auditions just to see how bad people could be. And he was joyously and transcendently bad. And I thought, "Oh! That's my in. I can be really bad at stuff." So I went and tried to audition for various things, like Halloween backup dancers. I tried to audition for that. They said I had "good enthusiasm." Because I had not budgeted enough dance per minute, so I had a song that went on for like four minutes, and then I had a dance that turned out only to go for approximately 30 seconds. And it was not ideal.
Subsequently, I went to a beauty pageant to test this theory out further. And the funny thing about beauty pageants is I really should have gotten on this bus earlier because once you're over 25, you're in a category that goes from 25 to deceased and is called Crones. And it's just you and like, there's four people. But yeah, I also auditioned for "America's Got Talent." And I tried to combine a bunch of different non-talents together. Like try to speak in tongues and twirl around and do a whole bunch of stuff.
[KB] You describe this moment where you're, what I imagine is, sort of deep in the throes of auditioning/trying/not trying, and you look over at one of the judges, and you felt like she knew.
[AP] She knows, yeah.
[KB] And that made you feel kind of terrible, which I think … so what was it about that moment that made you think, "Oh, I didn't get out of this what I thought I would."
[AP] Yeah, because I was sort of thinking, "Oh it would be easy. I won't ever have to really fail. What I'll get to do is work really hard — like fake fail — instead of just genuinely trying and being told that I'm not good enough." And instead, it was like, oh maybe I should have tried. Maybe I should have found what's something that I'm really going to be passionate about and get in there and do it and see how it goes instead of trying to look so bad on purpose that I could never see if I actually would look bad in reality.
[KB] I just thought it was such a great … I mean, that to me was one of the best realizations I've read in a long time, is you tried really hard to fail because it would be truly hilarious and wonderful, and it sounds like you're so open to experience that you're like, you're in. But then there is something about failing in that way that just didn't feel authentic to you.
[AP] No exactly. It wasn't real failure.
[KB] Because you weren't really trying –
[AP] I was trying to fail. And I failed at failing, which is like, meta, whoa. But it was also like — real failure is when you really put yourself out there, and you're earnest, and then you flop.
[KB] Yeah, I really do think it's something that is so close to bravery and is so close to authenticity and is a real, if done right, is not a facsimile of vulnerability. I think that people need to begin by accepting that the preconditions of life are that you will truly be made a fool of and that most of the fun things are ridiculous anyway.
[AP] Yes. Yeah.
[KB] Yeah, I think that too was part of the key of just learning to be sick in the world. There were times when I had to wear my chemotherapy fluids in a bag around my waist. And then I would have to carry more bags to hold the stuff that didn't fit on the other bags. And then it was just bags on bags on bags. And then it would go into a big sort of horse needle in my chest, and then I just walked around like a giant horrible cancer conversation piece. And if I didn't just allow the absurdity of the situation… like, yes I bedazzled it myself. And yes, I nicknamed my bag Jimmy Carter because I saw Jimmy Carter twice getting chemotherapy. I think if I didn't have that … it felt like it just gets harder and harder to be human anymore.
[AP] Yeah, because if you're not talking about the elephant in the room, I feel like people will really go out of their way to avoid talking about so many things. It can be very funny.
[KB] Exactly. Well, I mean that I think was one of the weirder revelations about my cancer diagnosis, is on one hand it made everyone incredibly, horribly awkward. Like every conversation always began with, "Well, my aunt." Or every uncle whose prostate really needs to be described to me right now, wherever I am. So when I read your book, I thought, "Yes! This is someone who accepts people as they really are." So I was wondering, do you think it makes you a better friend because you simply accept the weird?
[AP] I hope so. I think it makes my friends better friends because they're willing to have me around, too. I think it cuts both ways because, I don't know… My friends are always like, my fiancé and I, they're always like, "You two are friends with some people we would never be friends with." And I'm like, "No, but they're great. Once you really get to know name redacted, he's a terrific human being. It just takes you a little while."
Yeah, I was reading the back section of your book where you have "Things Never To Say To Anyone Experiencing Terrible Times," which was super useful because I feel like everyone's impulse is always to go, "Oh, the similar thing happened to me, and that will bond us together! My aunt's prostate…"
[KB] I think that's exactly right. I'm always caught in people's aunts' prostate situation, and I'm just trying to live and have a variety of experiences, and people continue to force me to have the same experience with them over and over again. I think it's just free association. "Hey, you remind me of cancer. Speaking of cancer, this horrible thing happened to me."
I guess the other thing I wondered when I read your book is that, you seem to have this incredible way of being funny and allowing that to help you grapple with something important. I wondered if there was ever a moment where being funny really helped you deal with something painful.
[AP] I think painful times are the times when people most turn to jokes. I feel like in movies and things, you see people, they're gathering around a sick bed, and they're all like, "Oh, let me tell you my regrets." And that's the last thing that's ever happened in my life in situations like that. Everyone's joking and trying to sort of cheer one another up. Like some of the dark humor, I feel like it's a reminder that you're still around.
[KB] Do you think there was ever a moment when being funny wasn't enough, when humor really let you down?
[AP] I think there are some things where you can sort of try to make jokes about it, but there's an inherent seriousness to the thing. I don't know, I guess sometimes if you're using it to try to insulate yourself from what's happening, it really doesn't work.
[KB] I kind of wondered though, I don't know, sickness is just part of the human experience. And I just wondered, why do you think we as people are so awkward about sick people in general? You'd think that people would have the sense that they are slowly climbing toward death. You know, I mean unless anyone has figured out an exception, other than Walt Disney. But I mean, you'd think that people would get that we're all going to die. And yet people seem very surprised and weird about it.
[AP] Yeah, everyone's like, "No but probably I won't. Everyone else will. Maybe in my case something different will occur." I don't know. I think if you look at all these pictures from the 19th century and stuff, people in their homes, you know grandma is sitting there in her bed and you have to sit there with that. You're walking around the house, and you're holding a baby in your arm, and there's old grandpa coughing his cough. I'm not sure, this is like a Renaissance painting at this point. His old timey grandpa cough. But like, all of these things were much more present, and you have to live around them and be with them, and now there are these very sterile facilities where you go and you do the thing, and then you come out and everyone's like, "Oh good it's over, and we don't have to discuss it because, well, here you are, so it must have been fine." It's sort of compartmentalized in a way that I think is, I guess sanitary, but maybe not healthy.
[KB] Yeah, that sounds right to me. I mean, it's just a little awkward for me because I have the hospital physically attached to the same place where I work. And so I have to leave the shiny world, put aside my velvet smoking jacket, and then walk down the steps and then walk over and then walk into another building, and then all of a sudden everyone's wearing face masks. And like, "Oh, we're doing something different here."
[AP] This is not the same!
[KB] There's no wine available here next to the liver section.
[AP] Yeah, why isn't there wine?
[KB] You have this hilarious essay where you help people talk to different age groups, like babies and then young people and middle-aged people. And you suggest that maybe people approach four year-olds with caution because they can actually remember things, or you have a list of helpful questions for 17-year-olds, like, "Do you still respect your parents?" — which I thought was really handy.
I have a few suggestions of how people can talk to sick people. But I wondered if we could just add a section to that essay about how to talk to people who are sick. I had a couple ideas for you. Number one is, tell them that everything happens for a reason, and then immediately supply that reason because they will want to know the reason.
[AP] Yeah, what is the reason?
[KB] I think people are waiting, and I have some reasons. And then second, then to just cut out health tips from Prevention Magazine for them, even though by definition they are already sick, so prevention is no longer an option.
[AP] I mean it's like nine-tenths of cure though right? Isn't it?
[KB] That's right. And so the rest of us are stuck without one tenth of a percent. Yeah. Yeah. That's right. In the end. I wonder if you had any other ideas for how to talk to sick people. Loud voices, probably, even though not many people are hard of hearing.
[AP] Loud and slow.
[KB] I do find that I've turned more and more to comedy as a way of trying to bump people out of that script, where I can see that they're looking at me, they can tell that I'm sick, and then I'm just about to try to preempt it.
[AP] Like if you say the thing, then they won't have the chance to say whatever bad idea they were going to say. So, at least you will have a different conversation.
[KB] Anyone, I can guarantee you that, anyone who talks to me will have a different conversation. Well, it was such a pleasure talking with you. Thanks so much for chatting with me.
[AP] Likewise, man.
[KB] This was the best. This was really fun.
…brief musical interlude…
[KB] Okay, I was having so much fun talking with Alexandra that I awkwardly completely forgot to ask her some of the things I wanted to know. Gauche, I know. But then again, today is all about awkwardness. So I'm going to take this opportunity to, that's right, uncomfortably, awkwardly call her back.
[AP] Hello.
[KB] Hey Alexandra, I am so sorry to call you back like this, but I just had a couple more questions.
[AP] All right.
[KB] So based on your age group, what do you think are the most common life script tragedies?
[AP] First, everyone has the grandparent loss, which is like you have the Facebook post, and then you have the people writing in and it's both sad but also something that you have had reason to anticipate over a period of time. So everyone's very weird about it. They're like, "Oh, how old were they?" And you're like, "86." And like, oh that's good! I mean not good but like, it's fine, right?
[KB] Exactly right. Everyone acts like it's, well, they'll give you like a measure of sadness based on how old they are.
[AP] It's like calibrated! It's weird. If you're like, "Oh, 70," they're like, "Aww." And if you're like, "90," they're like, "Well …".
[KB] Exactly. Grandparent loss, you're totally right.
[AP] And then there's also the one peer loss or the unexpected parent loss. I would say those are the two other ones.
[KB] Yeah. And then just the universalizing horror of failed relationships. Yes. Well I do have a sort of ongoing theory that anyone who hasn't been dumped a few too many times probably isn't a good person. Because how can they build character?
[AP] Yeah. No. How do you build character, and also, how do you know that you still like yourself even when X person doesn't like you?
[KB] Yeah, you have to decide in the face of overwhelming evidence that you're actually still okay.
[AP] Exactly! It builds gumption.
[KB] Yeah, or a sense of delusional grandeur. Like, either way it's going to work.
[AP] Both are necessary for us in life.
[KB] I think you're totally right. I did wonder, given your expertise in awkwardness, if you have any tips on how to get over awkwardness when you're with people who are actually going through awful times.
[AP] With the caveat that I'm super bad at this myself and no expert at all. I feel like all the times when I've been most terrified of like, "What am I going to possibly say when I get into this room?" — once you get into the room it's much easier. You just go and do it and be there. And once you're there, it makes so much more sense, and when you're like, "Oh my god, should I go? I won't even know what to say. I won't know what to do. Will we just sit around the whole time?" And sometimes you will just sit around the whole time and just watch Hallmark movies, the same one three times in a row, and that's fine. I guess just getting in the door in the first place and just being there, I feel is the hardest part.
[KB] Yeah. Yeah you're totally right. Have you ever been in a situation where you feel like you've failed a friend who's hurting, and maybe you wish you'd done better?
[AP] Yes. I mean, countless times. I think my nightmare is always that I will text somebody to invite them to something with their spouse and they will have already broken up and had been divorced for like three months and would have told me. So I'm always terrified. I'm bad at initiating. And I think my regret is that I haven't stepped up more and done the thing.
[KB] Well it's hard, especially when like, you're not even sure nothing has happened.
[AP] Yeah, I'm never sure what I'm supposed to say. After a breakup, I can be like, you are great, you are golden, you deserve the world, etcetera, etcetera. That I feel like I understand conceptually what people want to hear because that's what I wanted to hear myself at least, and I can extrapolate from that. But in other situations, I'm like, I don't know what to be like. Do people want me to give my thoughts on the subject, for me to sit here like this? Do we try to do an
And everyone always says, don't say, "Let me be there for you. I'm happy to help in any way," because you force the other person to suggest something. I'm always worried oh, no one will want my casserole. Although one time a friend was going through a grief period, and I'm like "I can bring you a casserole." And she was like, "Have you ever cooked anything resembling a casserole?" And I'm like, "No…" And she was like, "Thank you, I needed that laugh. So, inadvertently, I had provided something.
[KB] Well, thank you so much for doing this. I appreciate you popping back into my life.
[AP] Oh, I appreciate you. Thank you for popping back in. And I'm sorry that I did not to touch on the narrative and therefore required a separate, additional call. It was all a ruse, I swear.
[KB] I mostly just, I mostly just wanted to hear more about your problems. Thanks.
[AP] Here they are.
[KB] That's awesome.
[KB] So, I think I might just call Alexandra back every day from now on because holy crap, that was hilarious.
When something really terrible happens, it is so weird because it hits you at almost the same place as something that is really funny. It's just absurd. It's like completely surreal. So, I'm a normal person who suddenly got stage 4 cancer, and honestly, it made me hilariously accepting of reality that maybe shouldn't be reality.
Like the other day, a police officer came to my house and accused me of murder. Okay, this is what happened. A police car pulls up to my house, waits, a second police car comes. Officers get out and chat for a minute before approaching our door, warily.
Toban opens the door, and I hear muffled voices, and then my name. "I'm Kate Bowler," I announce loudly, stepping out onto the porch. "Well," says police officer on the right, "I'm sorry to have to tell you this, but you have been accused of murder."
And I could feel my brain freeze and then stop while my body gets that loose feeling I remember from the time I once fainted after working out to Richard Simmons' "Sweating to the Oldies."
"Just kidding," he says. "I think we have the wrong address," said the other. And I could barely hear them because I was already imagining my life behind bars.
But you know what I said? I said, "I sometimes have murderous thoughts." And then Toban elbowed me so hard because sometimes being accepting is not the best thing in the world.
[KB] Next time, I'm going to talk to someone who I think of as the human Tigger. Her name is Margaret Feinberg, and she's not just a really popular speaker and author, but she is the person I called when I got sick because she knows exactly what to say to make everything less terrible. You're going to love her.
Everything Happens is produced by Duke University in association with North Carolina Public Radio WUNC. Support comes from Faith and Leadership, an online learning resource. This podcast is produced by Beverly Abel and Alison Jones. Sound engineering is by Dennis Foley with assistance from Ivan Panaruski.
Special thanks to Amanda Wright and the Be the Change Revolution team, and Random House. And we'd love to hear from you. If you like what you're hearing, please post a review on iTunes. And while you're there, be sure to hit that "Subscribe" button.
You can find me on Facebook always, Instagram often, and Twitter every day @katecbowler. Let's chat. Until next time, this is Everything Happens with me, Kate Bowler.
4 Signs Your Gym is a Prosperity Church
Goodbye Light. Hello Darkness.
Discussion Questions for Alexandra Petri: Awkward


text:
Back to Journals » Journal of Multidisciplinary Healthcare » Volume 13
Changes in High-Density Lipoprotein Cholesterol Levels in Relation to Coffee Consumption Among Taiwanese Adults
Authors Chang HC, Nfor ON, Ho CC, Chen PH, Kung YY, Hsu SY, Tantoh DM, Liaw YC, Hsieh CF, Liaw YP
Received 10 August 2020
Accepted for publication 29 September 2020
Published 2 November 2020 Volume 2020:13 Pages 1427—1432
DOI https://doi.org/10.2147/JMDH.S276395
Huan-Cheng Chang,1,2 Oswald Ndi Nfor,3 Chien-Chang Ho,4,5 Pei-Hsin Chen,3 Ya-Yu Kung,6 Shu-Yi Hsu,3 Disline Manli Tantoh,3,7 Yi-Ching Liaw,8 Chuan-Fa Hsieh,9,10 Yung-Po Liaw3,7
1Division of Family Medicine, Department of Community Medicine, Landseed International Hospital, Taoyuan City 324, Taiwan; 2Department of Health Business Management Administration, Hungkuang University, Taichung City 43302, Taiwan; 3Department of Public Health and Institute of Public Health, Chung Shan Medical University, Taichung City 40201, Taiwan; 4Department of Physical Education, Fu Jen Catholic University, New Taipei 24205, Taiwan; 5Research and Development Center for Physical Education, Health, and Information Technology, Fu Jen Catholic University, New Taipei 24205, Taiwan; 6Division of Health Management, Landseed International Hospital, Taoyuan City 324, Taiwan; 7Department of Medical Imaging, Chung Shan Medical University Hospital, Taichung City 40201, Taiwan; 8Graduate School of Frontier Sciences, University of Tokyo, Tokyo, Japan; 9Department of Medical Education, Research & Quality Management, Landseed International Hospital, Taoyuan City 324, Taiwan; 10College of Health Sciences & Technology, National Central University, Taoyuan City 32001, Taiwan
Correspondence: Yung-Po Liaw
Department of Public Health and Institute of Public Health, Chung Shan Medical University, No. 110, Sec. 1 Jianguo N. Road, Taichung City 40201, Taiwan
Tel +886-4-24730022 ext.11838
Email Liawyp@csmu.edu.tw
Chuan-Fa Hsieh
Department of Medical Education, Research & Quality Management, Landseed International Hospital, No. 77, Guangtai Road, Pingzhen City, Taoyuan, Taiwan
Tel +886-3-4941234 ext. 2172
Fax +886-3-20641333-4246
Email hsiehcf@landseed.com.tw
Purpose: High-density lipoprotein cholesterol (HDL-C) is essential for cardiometabolic health. Coffee consumption influences the body's ability to regulate serum lipid profile. Although there is extensive information on coffee and cholesterol, not much is known whether changes in HDL-C concentrations are affected by coffee with or without flavoring substances.
Materials and Methods: Using historical data collected from 1272 participants in Li-Shin (Landseed) International Hospital in Northern Taiwan, we examined the relationship between HDL-C and consumption of plain black coffee with and without additives. Data on coffee consumption between 2006 and 2019 were collected based on self-reported questionnaires while HDL-C measurements were obtained from the electronic medical records of the hospital. t-test, chi-square test and multivariate linear regression analysis were used for analysis.
Results: In our primary analysis, we found that coffee consumption of ≥ 5 cups per week was positively associated with HDL-C (β = 1.9586, p=0.0442) compared with the lowest level (< 1 cup/week) of consumption. We found in a separate model that higher (≥ 5 cups/week) or lower (1– 4 cups/week) consumption of plain black coffee without additives was associated with higher HDL-C. The corresponding β values were 4.0674 (p = 0.0007) and 4.1253 (p = 0.0008), respectively. However, HDL-C levels were not affected by coffee with additives.
Conclusion: We found that consumption of black coffee without additives was associated with higher concentrations of HDL-C among Taiwanese adults over the age of 30. However, HDL-C levels did not change significantly among individuals who consumed black coffee with additives.
Keywords: coffee, cardiometabolic health, caffeine, lipid
High-density lipoprotein cholesterol is one of the major components of metabolic syndrome that have been greatly associated with several conditions including cardiovascular diseases (CVD).1 Managing dyslipidemia (defined as high concentrations of triglyceride (TG) and low‐density lipoprotein cholesterol (LDL‐C), and/or low HDL‐C)2 is an important step aimed at reducing CVD risk.2,3 In recent years, lipid therapy had been seen as an appropriate means of preventing coronary heart diseases.4 Of the serum lipids, HDL-C has been widely investigated and found to be influenced by several lifestyle variables including exercise, alcohol drinking, diet, coffee consumption, and body mass index.5 However, its association with coffee consumption has remained inconsistent.6–8
Coffee consumption is increasing rapidly in many parts of the world including Taiwan. Observational studies have suggested that drinking 1–4 cups of coffee a day may help to reduce the risk of MetS.9–11 According to evidence from previous epidemiological studies, moderate coffee drinking appears to be beneficial to cardiovascular health.12–14 On the other hand, contrary findings have also emerged.15,16 Because of the variability previously observed across studies, more investigations are required to clarify these associations.
Associations between normal coffee drinking and cardiometabolic risk factors or biomarkers (such as HDL-C, total cholesterol, and LDL-C) have so far been described.17 Nonetheless, results have been conflicting. With attention directed towards HDL-C, it remains debatable whether its concentration is altered by coffee as some have suggested that possible increases may depend on the type of coffee consumed.18 So far, no study to our knowledge has attempted to describe such an association in Taiwan. To clarify this, we compared changes in HDL cholesterol levels among Taiwanese adults who consumed plain black coffee with no additives versus plain black coffee with additives.
Data used in this study were from Li-Shin Outreach Neighborhood Screening (LIONS) project that was established in 2005 by the Landseed International Hospital in Pingzhen District, Taoyuan, Taiwan. The major objective of this project was to survey chronic disease and the potential risk factors among Taiwanese adults resident in PinZhen District.19 Eligible participants included those over 30 who had lived in the City for at least 30 years.20 These participants provided written informed consent. A self-administered questionnaire on medical history, lifestyle, and diet was completed by each participant before going through physical examinations. The LIONS project was conducted in accordance with the Declaration of Helsinki, and approval for this study was by the Institutional Review Board of Li-Shin Hospital (LSHIRB No./Protocol No 17–019).
In this study, the overall data were from 1272 participants who were recruited between 2006 and 2019.
Assessment of Coffee Consumption
Information on coffee consumption and other lifestyle variables was collected based on self-reported questionnaires. Participants responded "yes" to having a habit of drinking coffee. They reported drinking either plain black coffee alone or together with additives, and the number of cups consumed each week. Each cup had a capacity of approximately 240 mL. Alcohol drinkers were those who consumed on average 350 cc of wine, or 150 cc of beer, or 10 cc of spirit or distilled liquor (whiskey, vodka, rum, etc.) per day. Details of the other lifestyle variables in our model have been previously described.21
Assessment of Blood Lipids
Blood samples were collected from patients (n = 1272) at Li-Shin hospital. Serum concentrations of HDL-C and other lipids were measured using the Hitachi 7600/7180 automated biochemical analyzer (Hitachi, Tokyo, Japan).
We performed statistical analysis using the SAS 9.4 (SAS Institute Inc., Cary, North Carolina, USA) version. Coffee consumption was categorized as <1, 1–4, and ≥5 cups per week. We compared categorical variables using the Chi-square test. Paired samples were compared using the Student's t-test. Results were represented as mean ± standard deviation (SD) or as n (%). Multivariate linear regression analysis was performed to evaluate the effect of coffee on HDL-C. Independent parameters included age, sex, cigarette smoking, alcohol intake (betel nut chewing, body mass index, determined as weight (kg)/height (m2), vegetarian diet, exercise, and non-HDL cholesterol, defined as total cholesterol minus the HDL-C (<130 mg/dl representing normal values, and ≥ 130 mg/dl representing higher values). The β-coefficients and p-values were reported.
Demographic characteristics of the study participants are presented in Table 1. The mean HDL-C was 57.43 mg/dL among participants who consumed black coffee with additives and 60.37 mg/dL among those who consumed only plain black coffee (p = 0.0007). Association of HDL-C with overall coffee consumption is presented in Table 2. Compared with the lowest level of coffee consumption (<1 cup/week), coffee consumption of ≥5 cups/week was associated with higher HDL-C (β = 1.9586, p=0.0442). However, coffee consumption of 1–4 cups/week was not associated with HDL-C (β = 1.5635, p=0.0919). HDL-C levels were lower (β = −2.3558, p=0.0021) in participants with higher levels of non-HDL (≥ 130 mg/dl) compared with the lower levels (≤130mg/dl). We also observed that men had lower HDL-C than women (β = −11.7347, p<0.0001). Furthermore, HDL-C levels of current smokers were lower than in never smokers (β = −2.3824, p = 0.0304). Compared with nondrinkers, alcohol drinking was significantly associated with higher HDL-C among former (β = 5.7309, p = 0.0083) and current (β = 5.7832, p<0.0001) drinkers. We also examined changes in HDL-C levels based on consumption of coffee brewed with and without additives (Table 3). When the category, <1 cup/week of black coffee with additives was used as the reference category, the corresponding β-coefficients for categories of 1–4 and ≥5 cups/week of black coffee with additives were 0.4995 (p = 0.6488) and 0.8860 (p=0.4543), respectively. Those for categories of <1, 1–4, and ≥5 cups/week of black coffee without additives were 1.9295 (p = 0.3052), 4.0674 (p = 0.0007), and 4.1253 (p = 0.0008), respectively.
Table 1 Demographic Characteristics of Study Participants
Table 2 Changes in HDL-C Concentrations Based on Coffee Consumption
Table 3 Changes in HDL-C Based on Consumption of Plain Black Coffee with and without Additives
In this study, we observed that coffee consumption of ≥5 cups per week was greatly associated with higher levels of HDL-C among Taiwanese adults 30 years and older. However, there was no association between HDL-C and coffee consumption of 1–4 cups per week. Prior clinical studies have suggested that higher consumption of coffee may improve HDL-C.22,23 On the contrary, other studies have found no association between coffee consumption and HDL-C.17,24,25
In this study, we performed more analysis to determine whether changes in HDL-C are affected by coffee brewed with or without additives. When we used the lowest category, <1 cup/week of black coffee with additives as the reference group, we found that the association between coffee and HDL-C was stronger only among those that consumed 1–4 (β = 4.0674, p = 0.0007) and ≥5 cups (β = 4.1253, p = 0.0008) of plain black coffee without additives. Higher (≥5 cups/week) or lower (1–4 cups/week) consumption of plain black coffee with additives did not have any substantial effect on HDL-C levels. Findings from a randomized cross over study showed that HDL-C levels of patients who consumed a single 6-oz cup of black coffee with no flavoring substances significantly rose from 43.2 mg/dL to 44.8 mg/dL (p<0.001).26 However, no significant changes were observed among patients who consumed coffee with creamer and sugar. The biological mechanism by which black coffee may alter HDL-C levels is not clear. However, according to Cheung and his colleagues, such an increase may be associated with the concomitant decrease in triglycerides.26 Further investigations are required to support or clarify these findings.
In the primary analysis, we observed that HDL-C values were relatively lower in men than women. Another interesting finding was that higher concentrations of non-HDL-C (≥130 mg/dl) were greatly associated with lower HDL-C (β = −2.3558 (p = 0.0021). Higher values of non-HDL cholesterol are predictive of cardiovascular disease: Decreased levels have been associated with a lower risk of cardiovascular diseases among older adults.27 In our study, overweight and obesity also showed a strong but negative association with HDL-C. Physical exercise was weakly associated with HDL-C whereas the association did not differ by diet and betel nut chewing.
Despite these preliminary findings, it is wise stating our limitations. First, information on coffee consumption was collected based on a self-reported questionnaire. This might have introduced misclassification bias. Second, we could not determine the brew mechanism, the amount of coffee used, and the roasting time, which in part are believed to influence serum lipids. Next, data were not available on the exact ranges of cream, milk, sugar, or other flavoring substances that might have been used. Finally, data were from participants who were resident only in the Pingzhen District. Therefore, our findings may not be generalized.
Taken together, our findings indicated that consumption of black coffee without additives was associated with higher concentrations of HDL cholesterol among Taiwanese adults over the aged over 30 years. However, HDL-C levels were not affected by consumption of coffee with additives. We believe that these preliminary findings may be useful for future investigations on coffee drinking and cardiometabolic health.
This work was supported by funds from the collaborative projects between Chung Shan Medical University and Li-Shin International Hospital (CSMU-LSH-106-01).
1. Marjani AA. Review on HDL-cholesterol alterations in metabolic syndrome. J Biol Sci. 2013;13(8):679–684. doi:10.3923/jbs.2013.679.684
2. Haslam DE, Peloso GM, Herman MA, et al. Beverage consumption and longitudinal changes in lipoprotein concentrations and incident dyslipidemia in US adults: the Framingham heart study. J Am Heart Assoc. 2020;9(5):e014083. doi:10.1161/JAHA.119.014083
3. Nelson RH. Hyperlipidemia as a risk factor for cardiovascular disease. Prim Care. 2013;40(1):195–211.
4. Ventura HO, Lavie CJ, Mehra MR. HDL and heart failure regulation: still breathing but exhausted. J Am Coll Cardiol. 2019;187–189.
5. Steyn K, Fourie J, Benade A, et al. Factors associated with high density lipoprotein cholesterol in a population with high high density lipoprotein cholesterol levels. Arteriosclerosis. 1989;9(3):390–397. doi:10.1161/01.ATV.9.3.390
6. Corrêa TA, Rogero MM, Mioto BM, et al. filtered coffee increases cholesterol and inflammation biomarkers independent of roasting degree: a clinical trial. Nutrition. 2013;29(7–8):977–981. doi:10.1016/j.nut.2013.01.003
7. Zargar A, Auttapibarn C, Hong SH, Larson TJ, Hayworth KH, Ito MK. The effect of acute café latte ingestion on fasting serum lipid levels in healthy individuals. J Clin Lipidol. 2013;7(2):165–168. doi:10.1016/j.jacl.2012.11.001
8. Salonen JT, Happonen P, Salonen R, et al. Interdependence of associations of physical activity, smoking, and alcohol and coffee consumption with serum high-density lipoprotein and non-high-density lipoprotein cholesterol—a population study in eastern Finland. Prev Med. 1987;16(5):647–658. doi:10.1016/0091-7435(87)90048-X
9. Shang F, Li X, Jiang X. Coffee consumption and risk of the metabolic syndrome: a meta-analysis. Diabetes Metab. 2016;42(2):80–87. doi:10.1016/j.diabet.2015.09.001
10. Grosso G, Stepaniak U, Micek A, et al. Association of daily coffee and tea consumption and metabolic syndrome: results from the Polish arm of the HAPIEE study. Eur J Nutr. 2015;54(7):1129–1137. doi:10.1007/s00394-014-0789-6
11. Marventano S, Salomone F, Godos J, et al. Coffee and tea consumption in relation with non-alcoholic fatty liver and metabolic syndrome: a systematic review and meta-analysis of observational studies. Clin nutr. 2016;35(6):1269–1281. doi:10.1016/j.clnu.2016.03.012
12. Choi Y, Chang Y, Ryu S, et al. Coffee consumption and coronary artery calcium in young and middle-aged asymptomatic adults. Heart. 2015;101(9):686–691. doi:10.1136/heartjnl-2014-306663
13. Freedman ND, Park Y, Abnet CC, Hollenbeck AR, Sinha R. Association of coffee drinking with total and cause-specific mortality. N Engl J Med. 2012;366:1891–1904. doi:10.1056/NEJMoa1112010
14. Kokubo Y, Iso H, Saito I, et al. The impact of green tea and coffee consumption on the reduced risk of stroke incidence in Japanese population: the Japan public health center-based study cohort. Stroke. 2013;44(5):1369–1374. doi:10.1161/STROKEAHA.111.677500
15. Fung K, Biasiolli L, Hann E, et al. 9 Effect of coffee consumption on arterial stiffness from UK biobank imaging study. British Cardiac Society. 2019;A8–A10.
16. Wang Y, Tuomilehto J, Jousilahti P, et al. Coffee consumption and the risk of heart failure in Finnish men and women. Heart. 2011;97(1):44–48. doi:10.1136/hrt.2010.206045
17. Jee SH, He J, Appel LJ, Whelton PK, Suh I, Klag MJ. Coffee consumption and serum lipids: a meta-analysis of randomized controlled clinical trials. Am J Epidemiol. 2001;153(4):353–362. doi:10.1093/aje/153.4.353
18. Ricketts M-L. Does Coffee Raise Cholesterol? Taylor & Francis; 2007.
19. Chang H-C, Liang J, Hsu H-C, Lin S-K, Chang T-H, Liu S-H. Regular exercise and the trajectory of health-related quality of life among Taiwanese adults: a cohort study analysis 2006–2014. BMC Public Health. 2019;19(1):1352. doi:10.1186/s12889-019-7662-8
20. Chang H, Kung Y, Hsieh C, Hsiung L, Chang S, Chen T. Biological risk factors relevant to chronic disease in three ethnic groups in Taiwan: results from Li-Shin outreaching neighborhood screening (Lions A1). Ethn Dis. 2008;18(2):228.
21. Chang H-C, Hsieh C-F, Lin Y-C, et al. Does coffee drinking have beneficial effects on bone health of Taiwanese adults? A longitudinal study. BMC Public Health. 2018;18(1):1273.
22. Fried RE, Levine DM, Kwiterovich PO, et al. The effect of filtered-coffee consumption on plasma lipid levels: results of a randomized clinical trial. JAMA. 1992;267(6):811–815. doi:10.1001/jama.1992.03480060057030
23. Kempf K, Herder C, Erlund I, et al. Effects of coffee consumption on subclinical inflammation and other risk factors for type 2 diabetes: a clinical trial. Am J Clin Nutr. 2010;91(4):950–957. doi:10.3945/ajcn.2009.28548
24. Miyake Y, Kono S, Nishiwaki M, et al. Relationship of coffee consumption with serum lipids and lipoproteins in Japanese men. Ann Epidemiol. 1999;9(2):121–126. doi:10.1016/S1047-2797(98)00051-9
25. Cai L, Ma D, Zhang Y, Liu Z, Wang P. The effect of coffee consumption on serum lipids: a meta-analysis of randomized controlled trials. Eur J Clin Nutr. 2012;66(8):872–877. doi:10.1038/ejcn.2012.68
26. Cheung RJ, Gupta EK, Ito MK. Acute coffee ingestion does not affect LDL cholesterol level. Ann Pharmacother. 2005;39(7–8):1209–1213. doi:10.1345/aph.1G005
27. Brunner FJ, Waldeyer C, Ojeda F, et al. Application of non-HDL cholesterol for population-based cardiovascular risk stratification: results from the multinational cardiovascular risk consortium. Lancet. 2019;394(10215):2173–2183. doi:10.1016/S0140-6736(19)32519-X


The link below will take you to a set of excellent videos from our Local CCG.
The videos explain a whole range of Health Conditions and their treatment as well as providing information about child development, hospital discharge and much more. Each video is short and to the point. We recommend all our patients have a look at the videos that are relevant to their needs.


Consumer products companies lag behind many other industries in online sales, but in the US by 2022, we estimate that e-commerce could grow to $175 billion, or 15% of all consumer products sales. Companies not positioning themselves with the right digital strategy risk losing sales, market share, and growth potential.
Consumer behavior has been changing more slowly in consumer products than in some other spaces, but we expect the change of pace to accelerate. And many consumer products companies have been playing catch up in digital transformation, focusing more on internal capabilities rather than external strategies. Consumer products companies must implement forward-looking, digitally-enabled strategies to connect in new ways with consumers.


Beautiful park-like setting in exclusive Langhorne Manor. 2 bedrooms 1 bathroom in this second floor unit. Newer eat-in kitchen with stainless appliances and pantry area. Hardwood floors in both bedrooms and living room. Shared coin operated laundry facilities for your convenience. Assigned parking spaces and private backyard patio area is yours to set up for the summer! Heat is included in the rent! Neshaminy School District. No smoking. Call now to schedule a showing, won't last long!!
I was searching for a Property and found this listing (MLS® #PABU444350). Please send me more information regarding 841 W Gillam Ave #3, LANGHORNE, PA, 19047. Thank you!
I'd like to request a showing of 841 W Gillam Ave #3, LANGHORNE, PA, 19047 (MLS® #PABU444350). Thank you!


text:
March 2 (Wednesday)
House Group
Mar 2 @ 8:15 pm – 9:45 pm Andy and Nic's
March 16 (Wednesday)
Mar 16 @ 8:15 pm – 9:45 pm Andy and Nic's
April 6 (Wednesday)
Apr 6 @ 8:15 pm – 9:45 pm Andy and Nic's
April 13 (Wednesday)
Apr 13 @ 8:15 pm – 9:45 pm Andy and Nic's
May 4 (Wednesday)
May 4 @ 8:15 pm – 9:45 pm Andy and Nic's
May 11 (Wednesday)
May 11 @ 8:15 pm – 9:45 pm Andy and Nic's
June 1 (Wednesday)
Jun 1 @ 8:15 pm – 9:45 pm Andy and Nic's
June 15 (Wednesday)
Jun 15 @ 8:15 pm – 9:45 pm Andy and Nic's
Film Night
Jun 22 @ 7:30 pm – 9:30 pm ZOOM Meeting
*** FILM NIGHT IS ONLINE *** Tonight is a film night where we seek to enjoy a wholesome film, sometimes an old classic, other times an up-to-date Christian film. Typically we enjoy drinks and snacks at the same time.
July 6 (Wednesday)
Jul 6 @ 8:15 pm – 9:45 pm Andy and Nic's
July 13 (Wednesday)
Jul 13 @ 8:15 pm – 9:45 pm Andy and Nic's
August 3 (Wednesday)
Aug 3 @ 8:15 pm – 9:45 pm Andy and Nic's
August 10 (Wednesday)
Aug 10 @ 8:15 pm – 9:45 pm Andy and Nic's
September 7 (Wednesday)
Sep 7 @ 8:15 pm – 9:45 pm Andy and Nic's
September 14 (Wednesday)
Sep 14 @ 8:15 pm – 9:45 pm Andy and Nic's