Whether its heat, Cold, Rainfall, Drought, wind, storms so on and are on the extreme side of breaking records.. Record in here everytime something like this happens so we have a list of all the records broken starting from now.
Would like to start Melbourne has had its driest start to a year in 42 years.
Last time Melbourne passed its average rainfall during a 'Season' (Summer, Autumn, Winter or Spring) Was the Summer of 2005/2006 when 82mm fell in December, 54mm in January & 72mm in February. Every Season since then we have had below average rainfall which means the last 12 Seasons in a row we have had below average rainfall... I wonder if this has ever happend before since the records began in 1855? It wouldn't suprise me if this is the first time.
I doubt Johnno we have ever seen anything like that before, unless something similar happened before records began.
Couple of records to watch - Melbourne's record high June Maximum of 22.4C. Probably won't fall today, but it could get close. Also the record high Australian June record of 37.2C (was a lot of 35C in WA's north yesterday).
The most disturbing thing about the very mild weather this June is that it has been a fractionally cooler month than last June. Although we've actually had much cooler minimums this month in Melbourne.
And now with the driest first half of the year officially recorded in Melbourne and no doubt much of central VIC, it is just more evidence (if we really need more) that our climate is changing and becoming warmer and drier. I'm really dreading next summer.
Am I right in saying that today's 19.4c was the warmest 30th June on record?
so another record broken! This has been a year of records....and not all good ones either!
Also suspect it is currently the driest Jan->July on record. Tomorrow's rain may put us into 2nd last place (behind 1967).
tomorrow's rain? Will believe it when I see it!
Every month, every season is seeing records broken now for heat and dry. Melbourne has had no winter this year aside from a few minor periods of cold weather that barely register in amongst all the ridiculous mild weather. Back at home it has been cold, probably averaging around 10C or just under but for my elevation and 60km away from the coast that is warm for winter. Don't expect August to square the ledger, wouldn't be surprised to see some days approaching 30C in Melbourne by the end of the month and a 40C in early November.
Nothing surprises or shocks me with our climate anymore.
3rd driest Jan-> Jul on record for Melbourne.
To 9am this morning Melbourne's rainfall total is 39.2 mm for July, 165.0 mm for the year 2009 (thus far).
This yields the driest first seven months of the year since 1976 (159.9 mm).
1967 was also drier - 163.9 mm.
Sounds about right. In recent years we (in Ferny Creek) have been getting average or above average only about every 3rd month - this year Jan/Feb/May/Jun were very dry, Mar/Jul above average and April a bit below. You have to go back to late 2004/early 2005 to the last consistently wet spell of "weather".
It seems our new average is about 20% below the long-term average... puts Melbourne at about 500mm and Ferny Creek at about 1100mm.
Yeah thats how its going isn't it DJ.
Did some more research and from July 2004 to December 2005 in Melbourne 10 of the 18 months reached the average or passed it only 8 months were below average in that 18 month period which means 56% of the period throughout that time we had average or above average rain.. Now put that into perspective since then Jan 2006 only 10 months have reached average in 43 months thats 23% of the time since then we have had average or above rainfall thats a drop of over 30% in such a short amount of time.
Climate change and global warming has been spoken about since the 90's especially since the drier weather begain at the end of 1996 but whats changed even moreso since early 2006? For this to happen its another total level all together now! Thats a Big dip going by these stats in what was happening in 2004 & 2005 and whats happend since then its very disturbing infact.


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If, like me, you love Moroccan encaustic tiles or the decorative floors of Spain's Moorish palaces – and you still want a tile fix even if you are not heading out to Bologna for Cersaie this year – why not trot along to the Restaurant & Bar Design Show at ExCel on 26th and 27th September?
I can't promise a vast array of tile exhibitors, but I can guarantee that at least one very special portfolio will be laid out in all its glory. That is because Alhambra Tiles, who made such a strong impression at Clerkenwell Design Week earlier this year, will be exhibiting.
Restaurants are among Alhambra's biggest clients, and the company has fulfilled some very interesting projects, including bespoke colours, bespoke patterns and bespoke shapes; such as giant hexagons for the Stokehouse in the Nova Building, London. Other clients include Pizza Express, La Tasca, Parkers (Dubai), Pink Mamma (Paris), Gorms Pizza (Copenhagen) and the Nico Osteria Restaurant within the Thompson Hotel, Chicago … an impressive list indeed.
Alhambra can supply bespoke patterns for private clients, but also offers a cool choice of 'off-the-peg' designs; many of which come in at surprisingly low prices. Underlining the Moorish heritage conveyed by the company's name, stand-out ranges include the exquisite Granada and Seville / Cielo collections, which can provide a clear note of authentic Spanish style to any project.
In contrast to Alhambra's signature patterned tiles, the company has now curated a great selection of keenly-priced cement-effect porcelain; a truly on-trend collection for today's interior stylists.
Alhambra will also be presenting the fabulous yet functional Modern Industrial Range, whose Kilim Collection has undergone a quiet revolution of late.
And if past Tile Addict postings have alerted you to the delights and design possibilities of cobogós – pierced construction elements used to construct screens or walls that allow the passage of air and light, while at the same time providing privacy and protection – Alhambra has something to offer that is very hard to find in the UK. The fabulous Gaudi Lattice Brick Collection is billed by Alhambra as "the most cutting-edge thing out there, in our opinion, and not available from any other UK supplier, as far as we know." I tend to agree on both fronts.


text:
\section{}

\section{Introduction}

The manipulation of electron spins in semiconductors has attracted much interest during the last years due to potential applications for quantum  information processing.\cite{Awschalom2002,Zutic_ROMP76_323_04} Devices based on semiconductor spins require efficient techniques for the generation, storage, transport, and detection of the spin polarization, as well as interaction mechanisms for the manipulation of the spin vector in times shorter than the characteristic spin lifetime. One of the main challenges towards this goal in III-V semiconductor structures is the suppression of decoherence processes associated with the spin-orbit (SO) interaction, which reduces the lifetime of the electron spin polarization to values typically below one nanosecond and thus severely restricts its application in spintronic devices.

The SO-interaction describes the coupling between the spin vector and the varying lattice potential acting on a moving electron. In the electron reference frame, the SO-interaction translates into an effective magnetic field, $\mathbf{\Omega}_\mathrm{SO}$, which can lead to spin dephasing in an electron ensemble. Since $\mathbf{\Omega}_\mathrm{SO}$ depends on the electron's wave vector, $\mathbf{k}$, its magnitude and direction changes after each electron scattering event. As a result, electron spins with the same initial polarization but moving with different wave vectors will precess around different axes with different Larmor frequencies in-between two consecutive scattering events, leading to the well-known Dyakonov-Perel' (DP) spin dephasing mechanism.\cite{Dyakonov_SPSS13_3023_72,Dyakonov_SPS20_110_86} Improvement of the electron spin lifetime in these materials demands, therefore, the control of spin dephasing related to the SO-interaction.

In GaAs-based quantum well (QW) structures, the SO-interaction is governed by two major contributions. The first one is associated with the bulk inversion asymmetry (BIA) of the zinc-blende lattice. This contribution, known as the Dresselhaus hamiltonian,\cite{Dresselhaus55a} $\mathcal{H}_D$, is expressed as:

\begin{equation}\label{Eq_BIA}
\mathcal{H}_D=\frac{\hat{\sigma}}{2}\hbar\mathbf{\Omega}_D(\mathbf{k})=\frac{\gamma}{2}\sum_i^{x,y,z}\sigma_ik_i\left(k^2_{i+1}-k^2_{i+2}\right),
\end{equation}

\noindent where $\hbar$ is the reduced Planck constant, $\hat{\sigma}=(\sigma_x,\sigma_y,\sigma_z)$ are the Pauli matrices, $k_i$ are the wave-vector components along $\langle100\rangle$, and $\gamma$ is the Dresselhaus spin-splitting constant of the material (we follow here the convention introduced by Cardona\cite{Christensen_SSC51_491_84,Cardona_PRB38_1806_88} and Eppenga\cite{Eppenga_PRB37_10923_88}).

The second important contribution to the SO-interaction arises from the structural inversion asymmetry (SIA) introduced by an external field. In most cases, the SIA is generated by an electric field, $\mathbf{E}$, leading to the Rashba Hamiltonian, $\mathcal{H}_R$:\cite{Bychkov1984}

\begin{equation}\label{Eq_SIA}
\mathcal{H}_R=\frac{\hat{\sigma}}{2}\hbar\mathbf{\Omega}_R(\mathbf{k},\mathbf{E})=r_{41}\hat{\sigma}\cdot\mathbf{k}\times\mathbf{E},
\end{equation}

\noindent where $r_{41}$ is the Rashba coefficient.\cite{Winkler03a} Since the strength of $\mathbf{\Omega}_R$ depends on $\mathbf{E}$, the Rashba contribution provides a powerful mechanism for the electric manipulation of the spin vector.

The impact of the SO-interaction on the electron spin dynamics depends on the crystallographic growth direction of the QW.\cite{Dyakonov_SPS20_110_86} In the last years, GaAs QWs grown along the $[111]$ direction have attracted an increasing interest due to the special symmetry of the Dresselhaus and Rashba effective magnetic fields in this case. In the reference frame defined by the axes $\unitary{x}=\frac{1}{\sqrt{6}}(-1,-1,2)$, $\unitary{y}=\frac{1}{\sqrt{2}}(1,-1,0)$, $\unitary{z}=\frac{1}{\sqrt{3}}(1,1,1)$, and for a QW subjected to a transverse electric field $\mathbf{E}=E_z\unitary{z}$, these two contributions can be expressed as:\cite{Cartoixa05a}

\begin{eqnarray}\label{Eq_BIA111}
\hbar\mathbf{\Omega}_D(\mathbf{k})=\frac{2\gamma}{\sqrt{3}}\left(\langle k_z^2\rangle -\frac{1}{4}k_{\parallel}^2\right)\left[\begin{array}{c}k_y \\ -k_x \\ 0\end{array}\right] \nonumber \\
+ \frac{\gamma}{\sqrt{6}}k_y(k_y^2-3k_x^2) \left[\begin{array}{c} 0 \\ 0 \\ 1\end{array}\right]
\end{eqnarray}

\begin{equation}\label{Eq_SIA111}
\hbar\mathbf{\Omega}_R(\mathbf{k},E_z)=2E_zr_{41}\left[\begin{array}{c}k_y \\ -k_x \\0 \end{array}\right].
\end{equation}

\noindent Here, $\langle k^2_z \rangle=\left(\pi/d_\mathrm{eff}\right)^2$ is the averaged squared wave vector along $z$ determined by the spatial extension of the electron wave function, ${d_\mathrm{eff}}$, and $k_\parallel=(k_x^2+k_y^2)^{1/2}$ is the in-plane wave vector amplitude. At low temperature and electron populations, quadratic terms in $k_x$ and $k_y$ can be neglected, so that both $\mathbf{\Omega}_D$ and $\mathbf{\Omega}_R$ lie in the QW plane and have exactly the same symmetry. As a result, by adjusting $E_z$ to satisfy the condition:

\begin{equation}\label{Eq_SOcomp}
\mathbf{\Omega}_D(\mathbf{k})+\mathbf{\Omega}_R(\mathbf{k},E_z^{c})=0,
\end{equation}

\noindent the SO-interaction becomes simultaneously suppressed for all values of $\mathbf{k}$ at a well-defined compensation electric field, $E_z^c$, leading to long electron spin lifetimes. This compensation mechanism was originally proposed in the theoretical works by Cartoix\`a\cite{Cartoixa05a} and Vurgaftman.\cite{Vurgaftman_JAP97_53707_05} Recent experiments have provided evidence for the electric enhancement of the spin lifetime,\cite{Balocchi2011,PVS257} as well as for the transition from a BIA-dominated to a SIA-dominated spin dephasing with increasing electric field.\cite{PVS261} The effects of the non-linear \textit{k} terms in $\mathbf{\Omega}_\mathrm{SO}$ on the compensation mechanism have also been addressed.\cite{Sun_a__10,Wang_APL102_242408_13,Balocchi_NJ15_95016_13,PVS272}

A further important requirement for the efficient use of the spin degree of freedom in semiconductor devices is that carriers must be able to move from one point of the semiconductor to another one without losing their spin polarization. This requires not only long spin decoherence times but also good spin transport properties. Studies of spin diffusion in GaAs have been performed in the last years in bulk,\cite{JKDA99a, Crooker_Science_309_2191_05, Yu_APL94_202109_09, Quast_PRB79_245207_09, PhysRevB.87.205203, Weber_JAP109_106101_11, PhysRevB.88.195202} as well as in intrinsic,\cite{Cameron_PRL76_4793_96, Eldridge_PRB77_125344_08, Zhao_PRB79_115321_09, Hu_NRL6_149_11,PVS276} and n-doped QWs\cite{Weber_N437_1330_05, Carter_PRL97_136602_06, Volkl_PRB83_241306_11, Volkl_PRB89_75424_14, Altmann_PRB90_201306_14, Kohda_APL107_172402_15, Altmann_PRB92_235304_15} grown along different orientations. Although the spin transport properties were initially supposed to be the same as those of the charge, several results showed that this is not always true: while the charge transport in a carrier ensemble is not affected by carrier-carrier elastic scattering, this kind of interaction can play an important role in the case of spin transport. An example of this different behavior between carrier and spin transport is the spin Coulomb drag mechanism observed during unipolar spin diffusion in n-doped QWs.\cite{amico01a,Weber_N437_1330_05}

It has been recently shown that the spin diffusion length in GaAs (111) QWs can be efficiently controlled by a transverse electric field induced by a top electric gate.\cite{Wang_NC4_2372_13} Of special importance for future applications is the relation between the spin and carrier transport in these structures. In this contribution, we report experimental studies of both charge and spin transport in an intrinsic GaAs (111) QW under the effect of vertical electric fields. In our experiments, a cloud of out-of-plane spin polarized electron-hole (\textit{e-h}) pairs is optically generated by a tightly focused laser beam, and the expansion of this cloud under a transverse electric field is studied by spatially and time-resolved $\mu$-photoluminescence (PL). We show that the transport properties of out-of-plane electron spins depend on the applied electric field. We propose an explanation based on the precession of the spin vector around a weak in-plane SO-field during the radial expansion of the electron-hole cloud, finding a good agreement between simulation and experimental data. At SO-compensation, the suppressed precession of the spin vector around the SO-field allows the transport of the out-of-plane spin polarized electrons over distances exceeding $10~\mu$m. Under these conditions, the decay of the electron population in a few nanoseconds due to electron-hole recombination is the main mechanism limiting the spin transport distance.

This manuscript is organized as follows: in Section~\ref{Sec_setup} we introduce the sample design and the experimental techniques for the optical injection and detection of spin-polarized carriers. Section~\ref{subsec_carrier} shows the experimental results of charge transport obtained from both time-integrated and time-resolved experiments. Section~\ref{subsec_spin} shows the corresponding results for the case of spin transport, followed by a discussion of a spin drift-diffusion model in Section~\ref{Sec_discussion}. Finally, Section~\ref{Sec_summary} summarizes the main points of our work.

\section{Experimental details}\label{Sec_setup}

\begin{figure}
\includegraphics[width=\columnwidth]{fig1}
\caption{(a) GaAs single quantum well (SQW) embedded in a \textit{n-i-p} structure grown along [111]B. The bias voltage, $V_b$, applied between the top $n$ region and the $p$-doped substrate generates the electric field, $E_z$, for the control of the SO-interaction. Spin polarized carriers are optically generated by a tightly focused pulsed laser. The carriers spread and recombine emitting photoluminescence (PL) away from the excitation spot. Panels (b) and (c) show the images of the time-integrated right ($I_R$) and left ($I_L$) circular PL components with wavelength (vertical scale) and position sensitivity along $y\parallel[1\overline{1}0]$ (horizontal scale) with respect to the generation point, $y=0$. The dashed boxes mark the PL of the \textit{e-hh} transition. (d) Intensity profiles of $I_R$ and $I_L$ emitted by the \textit{e-hh} transition along $y$. The dotted line shows the spatial distribution of the tightly focused laser beam, with a full width at half maximum, $\phi_L=1$~$\mu$m. The experiment was done at 30~K and $V_b=-1.5$~V.\label{setup}}
\end{figure}

The experiments reported here were carried out in an undoped single GaAs/AlGaAs QW with a thickness of 25~nm  embedded in the intrinsic region of a
\textit{p-i-n} diode structure, cf.~Fig.~\ref{setup}(a). The sample was grown by molecular beam epitaxy on a $p$-doped GaAs(111)B substrate tilted by a small angle ($\delta\theta=2^\circ$) towards the $x$-direction (further details about the sample growth process can be found at Ref.~\onlinecite{PVS272}). The bias voltage, $V_b$, applied between an Al Schottky contact on top of the $n$-doped layer and the $p$-doped substrate, generates the vertical electric field $E_z$ required for the control of the SO-interaction. From previous measurements in a similar sample, we expect to reach $E_z^c$ at a reverse voltage bias $V_b\approx-1.5~$V.\cite{PVS261, PVS272} To confine the electric field along the $z$-direction, we processed the top doped layer and part of the top undoped (Al,Ga)As spacer into mesa structures of 300~$\mu$m diameter defined by wet chemical etching.

The spectroscopic studies were carried out with the sample in a cold finger cryostat at a temperature $T=30-40$~K equipped with a window for optical access and electric feed-throughs for the application of bias voltages. We optically excited \textit{e-h}~ pairs with spin vector pointing perpendicular to the QW plane by using a circularly polarized, pulsed laser beam with wavelength of 756~nm, pulse width of 150 ps, and repetition rate of 40~MHz. The beam was spatially filtered and tightly focused onto a spot with a diameter (full width at half maximum)  $\phi_L=1~\mu$m by a 50$\times$ microscope objective. The carrier cloud generated by the laser beam spreads outwards leading to a PL area extending over several $\mu$m around the generation spot. This PL was collected by the same objective and split into two beams with intensity proportional to its left ($I_L$) and right ($I_R$) circular components, which were then imaged by a cooled charge-coupled detector (CCD) placed at the output of a spectrometer. The input slit of the spectrometer was placed parallel to the $y\parallel[1\overline{1}0]$ surface direction of the sample, so that the images of $I_R$ and $I_L$ were collected at the CCD with energy (vertical scale) and spatial resolution along $y$ (horizontal scale). In addition to spatially resolved, time-integrated profiles, we have also recorded time-resolved profiles by using a gated CCD camera synchronized with the laser pulses.

$I_R$ and $I_L$ were used to determine the time and spatial dependence of the carrier density, $n=I_R+I_L$ (we suppose $n=n_e=n_h$ because the QW is non-doped), as well as  the out-of-plane spin density $s_z=I_R-I_L$. As the spin polarization of the photoexcited holes is lost within a time (few picoseconds\cite{PhysRevLett.67.3432,PhysRevLett.89.146601}) much shorter than the \textit{e-h}~ recombination lifetime, the difference between $I_R$ and $I_L$ only gives information about the out-of-plane component of the electron spin vector within the \textit{e-h}~ ensemble. The out-of-plane spin polarization, $\rho_z$, was obtained according to $\rho_z=s_z/n=(I_R-I_L)/(I_R+I_L)$.  We limit the use of $\rho_z$, however, to time-integrated measurements, where the number of counts in the CCD for both $I_R$ and $I_L$ is significantly above the noise signal everywhere along $y$. As this is not always true in time-resolved experiments, in this case we only discuss $s_z$ to avoid dealing with meaningless values of the division $s_z/n$.

\section{Results}\label{Sec_results}

\subsection{Carrier dynamics}\label{subsec_carrier}

Figures~\ref{setup}(b) and (c) compare time-integrated images of $I_R$ and $I_L$ recorded with spectral (vertical axis) and spatial resolution (horizontal axis) for $V_b=-1.5$~V. The position of the 1~$\mu$m-wide laser spot used for excitation is $y=0$. The dashed rectangles indicate the PL emitted by the electron-heavy hole (\textit{e-hh}) transition. Figure~\ref{setup}(d) shows the corresponding intensity profiles of $I_R$ and $I_L$ for the \textit{e-hh} transition as a function of the distance to the laser spot, while the dotted line displays, for comparison, the intensity profile of the tightly focused laser beam. As expected, the \textit{e-hh} emission region extends over an area much larger than the diameter of the excitation spot due to the radial ambipolar transport of photogenerated electrons and holes. The shape of the measured PL profile deviates from the expected one, symmetric to $y=0$, due to terraces at the sample surface, which originate from the growth on a surface tilted by an angle $\delta\theta$ with respect to the [111] direction.\cite{PVS272}

\begin{figure}
\includegraphics[width=\columnwidth]{fig2}
\caption{Time and spatially resolved carrier density, $n$, along the $y$-direction after the laser pulse injects electron-hole pairs at $t=0$. Panel (a) shows the two-dimensional color profile for $V_b=1$~V, while panel (b) shows the spatial profiles of panel (a) for $t=0.5, 1.0, 1.5 ,2.0 ,2.5\mathrm{~and~}3.0$~ns (squares, circles, up triangles, down triangles, diamonds and left triangles). The solid lines are fittings to the data according to Eq.~\ref{Eq_2Ddiff}. Panels (c) and (d) show the corresponding results for $V_b=-1.5$~V. The experiment was performed at 30~K and a laser power of 20~$\mu$W. The curves are normalized to the maximum value at each panel.\label{charge_dynamics}}
\end{figure}

We have also performed time-resolved $\mu$-PL experiments using a time-gated CCD camera. Figure~\ref{charge_dynamics}(a) shows a two-dimensional color plot of the carrier density, $n$, as a function of the position along $y\parallel[1\overline{1}0]$ (horizontal scale), and the time delay with respect to the laser pulse (vertical scale) for $V_b=1$~V. Panel (b) displays the corresponding spatial profiles at the times marked with dashed lines in panel (a). After a fast initial expansion during the first nanosecond, the carrier motion slowers for longer time delays while $n$ also decays due to  \textit{e-h}~ recombination. In contrast, when $V_b=-1.5$~V (corresponding to an electric field close to $E_z^{c}$), the carrier expansion lasts longer, cf. panels (c-d). We attribute this behavior to the reduction of the \textit{e-h}~ recombination rate due to the electrically induced spatial separation of the electron and hole wave functions toward opposite barriers of the QW.

\begin{figure}
\includegraphics[width=0.9\columnwidth]{fig3}
\caption{Square of the full width at half maximum of $n$, $w_a$, as a function of time, obtained from the fitting of the curves of Fig.~\ref{charge_dynamics} to Eq.~\ref{Eq_2Ddiff}. The dashed lines are a guide to the eye.\label{charge_wa2vstime}}
\end{figure}

We can obtain the ambipolar carrier diffusion coefficient, $D_a$, and the \textit{e-h}~ recombination time, $\tau_r$, from these time-resolved measurements by assuming that the optically generated carrier density, $n$, has an initial Gaussian shape. Under these conditions, the expansion of $n$ as a function of time, $t$, and radial distance, $r=|y|$, is described by the solution to a two-dimensional drift-diffusion model:\cite{Zhao_PRB79_115321_09}

\begin{equation}\label{Eq_2Ddiff}
n(r,t)=n_0\frac{w_0^{2}}{w_a^{2}(t)}\exp{\left(-\frac{4\ln(2)r^{2}}{w_a^{2}(t)}\right)}\exp{\left(-t/\tau_r\right)},
\end{equation}

\noindent where $n_0$ is the carrier density at $r=0$ and $t=0$, $w_0$ is the full width at half maximum (FWHM) of the initial carrier distribution, and $w_a(t)=[w_0^{2}+16\ln(2)D_at]^{1/2}$ is the FWHM of the profile as a function of time. Figure~\ref{charge_wa2vstime} shows values of $w_a^2$ obtained from the fits of Eq.~\ref{Eq_2Ddiff} to the profiles in Figure~\ref{charge_dynamics} at several time delays. The high quality of the fits is demonstrated by the solid lines superimposed on the experimental points in Figs.~\ref{charge_dynamics}(b) and \ref{charge_dynamics}(d). For both applied biases, $w_a^{2}(t)$ initially increases with a fast slope during the first nanosecond, followed by a slower evolution for larger time delays. We attribute the fast expansion just after the pulse ($t\leq1$~ns) to repulsive drift forces between carriers at the high density regions close to the generation spot. As the \textit{e-h}~ pairs were non-resonantly generated by the laser, an initial higher carrier temperature with respect to the lattice also contributes to the fast expansion with an initially higher diffusion coefficient. The evolution at $t>1$~ns is due to the radial transport of the thermalized electrons and holes driven by diffusion. From the linear fitting of $w_a^2(t)$ in this regime, we obtain $D_a\approx45$~cm$^{2}$/s. It is remarkable that, although the increase of $E_z$ enhances the \textit{e-h}~ recombination time from $\tau_r=2$~ns to 4~ns, $D_a$ is not significantly affected. To estimate the carrier scattering time, $\tau_p $, from $D_a$, we take into account that the Fermi energy for the carrier density present in the QW at $t>1$~ns is lower than the thermal energy. We can therefore apply the Einstein equation $D_a=\mu_ak_BT/q$, where $q$ is the electron charge, $k_B$ is the Boltzmann constant, and $\mu_a$ is the ambipolar mobility $\mu_a=2\mu_e\mu_{hh}/(\mu_e+\mu_{hh})$, whose value is intermediate between the electron and heavy hole mobilities, $\mu_e$ and $\mu_{hh}$ respectively. Our result is $\tau_p\approx3$~ps, in agreement with previously estimated values in a similar QW based on measurements of Dyakonov-Perel' spin dephasing time under homogeneous carrier concentration.\cite{PVS261,PVS272}

\begin{figure}
\includegraphics[width=0.9\columnwidth]{fig4}
\caption{Results of the fitting parameters of Eq.~\ref{Eq_2Ddiff} as a function of the applied bias for laser powers 40~$\mu$W (squares) and 80~$\mu$W (circles), measured at 40~K. (a) Carrier recombination time, $\tau_r$. (b) Ambipolar diffusion coefficient, $D_a$. The dashed lines in both panels are a guide to the eye.\label{charge_summary}}
\end{figure}

We have repeated the previous experiment for several voltage biases and laser powers, $P_{laser}$, to extract the dependence of $\tau_r$ and $D_a$ on $E_z$ and carrier density. Figure~\ref{charge_summary} shows (a) $\tau_r$ and (b) $D_a$ as a function of $V_b$ obtained from measurements performed at $P_{laser}=40~\mu$W (squares) and 80~$\mu$W (circles). The top horizontal scales depict the $E_z$ that corresponds to the applied $V_b$, which was determined from the energy shift of the PL due to the Quantum Confined Stark Effect (QCSE).\cite{PVS272} As expected, the spatial separation of electron and hole towards opposite QW barriers induced by $E_z$ increases the carrier lifetime. $D_a$, on the contrary, does not depend on applied bias. It increases, however, with the laser power, from 50~cm$^2$/s at 40~$\mu$W to 70~cm$^2$/s at 80~$\mu$W. We attribute the increase to the fact that a larger carrier concentration screens more efficiently the scattering centers that limit the carrier mobility in the structure.\cite{Remeika_PRL102_186803_09} An additional cause of this enhancement is that, for $P_{laser}\geq 80~\mu$W, the Fermi level approaches the thermal energy at the time range studied. Above this limit, $D_a$ becomes proportional to the carrier density.

\subsection{Spin dynamics}\label{subsec_spin}

\begin{figure}
\includegraphics[width=0.95\columnwidth]{fig5}
\caption{(a) Time-integrated, out-of-plane spin polarization, $\rho_z$, as a function of radial distance from the generation spot, $r$, under different voltage biases, $V_b$. Measured at 30~K and a laser power 125~$\mu$W. (b) Radial profiles of $\rho_z$ for selected bias voltages of panel (a). (c) $\rho_z$ at $r=0$ (open symbols) and at $r_t=10$~$\mu$m (solid symbols) as a function of $V_b$ and its respective electric field, $E_z$. The different simbols correspond to laser powers of 20~$\mu$W (squares), 40~$\mu$W (circles), 80~$\mu$W (triangles) and 125~$\mu$W (diamonds). The lines are a guide to the eye.\label{spin_pol}}
\end{figure}

The large extension of the time-integrated PL profiles of Fig.~\ref{setup} relative to the laser spot diameter allows to determine the out-of-plane spin polarization, $\rho_z$, as the carriers move away from the excitation point. Figure~\ref{spin_pol}(a-b) shows $\rho_z$ vs. the radial distance, $r$, calculated from the time-integrated $I_R$ and $I_L$ profiles under different biases $V_b$. The experiment was performed using a laser power $P_{laser}=125~\mu$W. Figure~\ref{spin_pol}(c) compares the values of $\rho_z$ at the generation spot, $r=0$ (open diamonds), and at a radial transport distance, $r_t$, of 10~$\mu$m (solid diamonds) as a function of $V_b$ and its respective $E_z$. At $V_b=0$, $\rho_z$ decays from 0.16 at $r=0$ to 0.07 at $r_t$ due to spin precession around the SO-field between scattering events as the carriers move away from the generation spot. When the bias approaches $V_b=-1.8$~V, the linear Dresselhaus and the Rashba term cancel each other and the SO-interaction is suppressed. As a consequence, the electron ensemble expands without losing its initial out-of-plane spin polarization. Therefore, $\rho_z$ remains constant around $0.24$ all along the transport distance studied. At biases $V_b<-1.8$~V, the Rashba term overcompensates the Dresselhaus one. The SO-interaction becomes then active again and $\rho_z$ decreases. The observation of a maximum in $\rho_z$ at $V_b=-1.8$~V unambiguously establishes the BIA/SIA compensation as the mechanism for electrically induced spin transport enhancement in (111) QWs. The corresponding value of $E_z^{c}\approx~18$~kV/cm agrees well with PL results recorded in a similar sample using a larger illumination area.\cite{PVS261,PVS272}

It is noteworthy that the $\rho_z$ profile for $r=0$ in Fig.~\ref{spin_pol}(c) is asymmetric with respect to the compensation bias $V_b=-1.8$~V. The asymmetry arises from the fact that, in a time-integrated PL measurement, $\rho_z$ depends on the ratio between the carrier recombination time, $\tau_r$, and the spin dephasing time, $\tau_s$, according to:

\begin{equation}\label{Eq_spinpol}
\rho_z=\rho_0/(1+\tau_r/\tau_s).
\end{equation}

\noindent Here, $\rho_0=0.25$ is the maximum electron spin polarization that can be achieved for excitation energies above the electron-light hole transition.\cite{Meier_84} While $\tau_r$ increases monotonously with $E_z$, cf. Fig.~\ref{charge_summary}(a), $\tau_s$ has a maximum at $E_z^c$ and decreases as the electric field moves away from the compensation field.\cite{Cartoixa05a, Vurgaftman_JAP97_53707_05, PVS261} Therefore, when $E_z$ exceeds $E_z^c$, $\tau_s<\tau_r$ and $\rho_z$ at $r=0$ goes to zero because the out-of-plane spin polarization is lost much before the electrons and holes recombine.

We have repeated the experiment of Fig.~\ref{spin_pol}(a) using several laser excitation powers, cf. Fig.~\ref{spin_pol}(c). As the number of optically injected carriers increases, we observe an enhancement of $\rho_z(E_z^c)$ at $r_t$, $\Delta\rho_z$. To understand this, we take into account that the photons detected at this point are emitted by \textit{e-h}~ pairs that recombine just after traveling from the generation spot to $r_t$ in an average time $r_t^2/D_a$. We have shown in Fig.~\ref{charge_summary}(b) that $D_a$ increases with laser power, thus reducing the traveling time of the carriers. As a consequence, a larger fraction of electrons reaches $r_t$ before losing their out-of-plane spin polarization.

In addition, larger laser powers shift $E_z^c$ by an amount $\Delta E_z$ towards larger values. We exclude thermal effects as the cause of this shift: higher temperatures would allow the occupation of energy states with larger $k$-vectors, whose contribution to the cubic terms of $\mathbf{\Omega}_\mathrm{SO}$ reduces $E_z^c$.\cite{Vurgaftman_JAP97_53707_05, PVS261, PVS272, Balocchi_NJ15_95016_13} We attribute the enhancement of $E^c_z$ to a partial screening of the electric field generated by the top gate. This screening comes from the accumulation of photoexcited electrons and holes at opposite walls of the QW as a response to the gate field.

\begin{figure}
\includegraphics[width=\columnwidth]{fig6}
\caption{Time and spatially resolved out-of-plane spin density, $s_z$, along the $y$-direction after the laser pulse injects electron-hole pairs at $t=0$. Panel (a) shows the two-dimensional color profiles for $V_b=1$~V, while panel (b) shows the spatial profiles for $t=0.5, 1.0, 1.5 ,2.0 ,2.5 ,3.0$~ns (squares, circles, up triangles, down triangles, diamonds and left triangles). The solid lines are simulations according to Eq.~\ref{Eq_szSimulation}. Panels (c-d) show the same as (a-b) for $V_b=-1.5$. The experiment was performed at 30~K and a laser power of 20~$\mu$W. The curves are normalized to the maximum value at each panel.
\label{spin_dynamics}}
\end{figure}

\begin{figure}
\includegraphics[width=0.9\columnwidth]{fig7}
\caption{Comparison of spatial profiles of $n$ (squares) and $s_z$ (circles) from Figs.~\ref{charge_dynamics} and \ref{spin_dynamics} for (a) $V_b=1$~V, and (b) $V_b=-1.5$~V, at a time delay of 2~ns. All curves are normalized to their maximum. The solid lines are simulations according to Eqs.~\ref{Eq_2Ddiff}, \ref{Eq_szSimulation} and \ref{Eq_angle}.
\label{spin_comparison}}
\end{figure}

\begin{figure}
\includegraphics[width=0.9\columnwidth]{fig8}
\caption{Spin decoherence time, $\tau_s$, estimated from the fitting of $s_z$ by Eq.~\ref{Eq_szSimulation}, as a function of the applied bias $V_b$ for laser powers 40~$\mu$W (squares) and 80~$\mu$W (circles), measured at 40~K. The curves show, for comparison, the spin decoherence time in an homogeneous electron distribution for out-of-plane spins (dashed lines) and precessing spins (dotted line), estimated according to Ref.~\onlinecite{PVS261}.\label{spin_summary}}
\end{figure}

Finally, we have also measured the time-resolved radial expansion of the out-of-plane spin density, $s_z$, in the same way as we did for $n$ in subsection \ref{subsec_carrier}. Figure~\ref{spin_dynamics} shows the spatial- and time-resolved evolution of $s_z$ corresponding to the carrier dynamics of Figure~\ref{charge_dynamics}. As in the case of $n$, $s_z$ expands over an area much larger than the diameter of the excitation spot. A comparison of the temporal decay of $n$ and $s_z$ for $V_b=1$~V (panels (a-b) of Figures~\ref{charge_dynamics} and \ref{spin_dynamics}) shows that the amplitude of $s_z$ decreases slightly faster than $n$ due to the fact that the decay of $s_z$ includes spin dephasing in addition to carrier recombination. On the contrary, for the compensation bias $V_b=-1.5$~V (see panels (c-d) in the same figures), the amplitude decays of $n$ and $s_z$ are very similar. The latter is attributed to a negligible spin dephasing within the recombination lifetime of the carriers due to SO-compensation. The decay of the spin density must, therefore, follow the one of the carrier density. As the lifetime of the photogenerated carriers is only a few nanoseconds, the main mechanism limiting spin transport in intrinsic GaAs (111) QWs at SO-compensation is electron-hole recombination.

Interestingly, the spatial extension of $s_z$ also depends on $V_b$. Figure~\ref{spin_comparison} compares the normalized profiles of $n$ (squares) and $s_z$ (circles) at $t=2$~ns for (a) $V_b=1$~V and (b) $V_b=-1.5$~V. In the case of $V_b=1$~V, the profile of $s_z$, with a FWHM of $w_s=8.6~\mu$m, is clearly narrower than the one of $n$ ($w_n=12.7~\mu$m). When $V_b=-1.5$~V, in contrast, both profiles have a similar spatial extension of $w_n=13.7~\mu$m and $w_s=12.2~\mu$m, respectively. The discrepancy in the profile widths for biases away from SO-compensation is due to the coherent precession of the spin vectors around the SO-field during the two-dimensional expansion of the inhomogeneous electron population. When the Dresselhaus and Rashba terms fulfill special symmetries, the interplay between the Brownian motion of the carriers and the spin-orbit field can correlate the orientation of the spin vector at spatially separated points in the electron ensemble.\cite{Froltsov_PRB64_45311_01, Stanescu_PRB75_125307_07, Yang_PRB82_155324_10, Poshakinskiy_PRB92_45308_15} The most extreme example is the persistent spin helix observed in GaAs (001) QWs for a particular ratio between the Dresselhaus and Rashba terms.\cite{Bernevig_PRL97_236601_06, Koralek_N458_610_09, Walser2012} In GaAs (111) QWs, the linear Dresselhaus contribution and the Rashba one have the same symmetry. Therefore, the SO-interaction at low temperatures can be treated as a single in-plane term with the symmetry of the Rashba contribution. In this case, the two-dimensional expansion of an initially narrow out-of-plane spin ensemble leads to oscillations of $s_z$ along $k$ in the momentum space that are described by a Bessel function.\cite{Stanescu_PRB75_125307_07} These Bessel-like oscillations are also present in the analytic solution of $s_z(r,t)$ at times fulfilling $t\gg r^2/D$, with the first node appearing at $r_n=2.4837\sqrt{D\tau_s}$.\cite{Froltsov_PRB64_45311_01, Stanescu_PRB75_125307_07, Poshakinskiy_PRB92_45308_15, Altmann_PRB92_235304_15} In our experiments, the maximum radial distance is $r_t=10~\mu$m and the ambipolar diffusion coefficient is $D_a\approx50$~cm$^2$/s, thus leading to $r_t^2/D_a\approx20$~ns. The \textit{e-h}~ recombination time in our sample is, however, only a few nanoseconds, cf. Fig.~\ref{charge_summary}(a). The spin density profiles of Figs.~\ref{spin_dynamics} and \ref{spin_comparison} correspond, therefore, to the opposite limit $t\ll r^2/D$, where no analytic solution in the spatial domain exists.\cite{Stanescu_PRB75_125307_07} In addition, the value of $\tau_s$ for the range of applied voltage biases (cf. Fig.~\ref{spin_summary}) implies that the first node appears at radial distances exceeding $r_t$. This means that the optically injected \textit{e-h}~ pairs disappear well before the oscillation of $s_z$ along $r$ can be observed.

\section{Discussion}\label{Sec_discussion}

It is possible to obtain an analytic approximation to $s_z$ in the real space for $t\ll r^2/D$ if we take into account that, for the short carrier lifetime and weak SO-interaction of our experiment, the precession angle of the spin vectors in the ensemble is expected to be small. Under this assumption, the spatial profile of $s_z$ will resemble that of $n$ and can be approximated by:

\begin{equation}\label{Eq_szSimulation}
s_z(r,t)=n(r,t)\exp(-t/\tau_s)\cos[\theta(r,t)].
\end{equation}

Here, the cosine accounts for the projection along $z$ of the tilted spin vector due to its slight precession around $\mathbf{\Omega}_\mathrm{SO}$ during the radial expansion.\footnote{Although a Bessel function is a more appropriate solution for a radially symmetric differential equation than a harmonic oscillation, both functions behave similar for $r\ll r_n$.} To determine the precession angle $\theta(r,t)$ of the spin ensemble, we proceed as follows: during an infinitesimal time interval $dt$, an electron spin vector moving with an in-plane momentum $\mathbf{k}$ rotates an infinitesimal angle $d\mathbf{\theta}=\mathbf{\Omega}_\mathrm{SO}(\mathbf{k}) dt$. Taking into account only the linear in-plane $k$ terms in Eq.~\ref{Eq_BIA111}, and using the relations $\hbar\mathbf{k}=m^*\mathbf{v}$ and $\hbar^2\langle k^2\rangle\approx 2m^* k_BT$, we can express $\mathbf{\Omega}_\mathrm{SO}$ as:

\begin{equation}\label{Eq_OmegaSOv}
\mathbf{\Omega}_\mathrm{SO}(r,t)= g(T,E_z)(\mathbf{v}\times\unitary{z}),
\end{equation}

\begin{equation}
g(T,E_z)=\frac{2m^*\gamma}{\hbar^2\sqrt{3}}\left[\langle k_z^2\rangle -\frac{m^*}{2\hbar^2}k_BT-\sqrt{3}\frac{r_{41}}{\gamma}E_z\right].
\end{equation}

\noindent Here, $g(T,E_z)$ is the SO-precession angle per unit distance, and it fulfills $g(T,E_z^c)=0$. In our model, we assume that, during the early stage of the expansion process, the carriers generated within the laser spot follow a trajectory close to the radial one. This means that the instantaneous velocity of each carrier can be expressed as $\mathbf{v}=v(r,t)\hat{\mathbf{r}}+\mathbf{v}^*$. Here, $v(r,t)$ is the average radial velocity of the carrier ensemble, which is determined by the solution of the drift-diffusion differential equation, cf. Eq.~\ref{Eq_2Ddiff}. $\mathbf{v}^*$, on the contrary, is a perturbative random term that changes magnitude and direction after each scattering event. According to these definitions, the average precession angle, $\langle d\theta\rangle$, of the carriers contained in an infinitesimal area at $\mathbf{r}$ and $t$ during an infinitesimal time interval $dt$ is then just:

\begin{equation}
\langle\mathbf{\Omega}_\mathrm{SO}\rangle dt=g(T,E_z)v(r,t)dt(\unitary{r}\times\unitary{z}),
\end{equation}

\noindent because $\langle\mathbf{v}^*\rangle=0$. Therefore, $v(r,t)$ determines the infinitesimal precession angle around which the spin ensemble coherently precesses at each position and time, while $\mathbf{v}^*$ is responsible for the spread in precession angles that gives rise to the spin dephasing time $\tau_s$.

To obtain $\theta(r,t)$, we just add $\langle d\theta\rangle$ along the radial trajectory of the carriers from their initial position within the gaussian distribution $r_0$ at $t=0$ until they reach $r$ at $t$. By doing this, we are neglecting the effect on $\theta(r,t)$ of carrier diffusion along other trajectories than the radial one. Taking into account that $v=dr/dt$, the integral is simply given by:

\begin{equation}
\theta(r,t)=g(T,E_z)\int_{r_0}^r dr'=g(T,E_z)(r-r_0).
\end{equation}

\noindent The problem reduces to finding the initial radial position, $r_0$, of particles reaching the position $r$ at the time $t$. To do this, we take into account that the radial current density $j=qnv$ in a drift-diffusion process depends on $r$ and $t$ according to:

\begin{equation}\label{Eq_Fickslaw}
qn(r,t)v(r,t)=-qD_a\frac{\partial n(r,t)}{\partial r}+j_{d}(r,t).
\end{equation}

\noindent Here, the first term in the right side of the equation is the diffusion current determined by Fick's first law. The second term, $j_d=\mu_aF_r$, represents the radial drift current induced by the radial repulsive forces, $F_r$, between excitons and free carriers at the high density regions close to the generation spot. As discussed in Sec.~\ref{subsec_carrier}, $j_d$ is only important during a short time after the laser pulse, where it is responsible of the fast carrier expansion observed for $t<1$~ns. It can be shown that, due to the shape and radial symmetry of $n$, the radial profile of $j_d$ is similar to that of $\partial n/\partial r$.\footnote{The repulsive forces at $r=0$ must be $F_r=0$ because of the radial symmetry of the carrier density. Due its gaussian shape, the carrier concentration is the largest at the center and decays radially towards zero. Therefore, $F_r$ must initially increase with $r$ until reaching a maximum around $w_n/2$, and then decay towards $F_r\rightarrow0$.} We can therefore take $j_d$ into account by supposing that it is $j_d\approx-qD_{d}\partial n/\partial r$ for $t<1$~ns and neglect it afterwards. The carriers then expand with an effective diffusion coefficient $D_{eff}=D_a+D_d>D_a$ for $t<1$~ns, while for $t>1$ the expansion is purely diffusive and determined only by $D_a$.

Introducing now the carrier density, $n$, of Eq.~\ref{Eq_2Ddiff} and its derivative $\partial n/\partial r$ into Eq.~\ref{Eq_Fickslaw} and integrating $v=dr/dt$, we obtain the following relation between $r_0$ and $r$:

\begin{equation}\label{Eq_r}
\frac{r_0}{w_0}=\frac{r}{w_a(t)},
\end{equation}

\noindent which leads to the final expression for $\theta(r,t)$:

\begin{equation}\label{Eq_angle}
\theta(r,t)=g(T,E_z)r\left[1-\frac{w_0}{w_a(t)}\right].
\end{equation}

\noindent The precession angle at each point, therefore, increases with time from zero towards a finite value that saturates at long times. Remarkably, this result is qualitatively similar to the obtained for an initial spin polarization with finite spatial extension close to the spin helix regime,\cite{Walser2012} but differs in the fact that the width enters as $1-(w_0/w_a)^2$ in the spin helix case.\cite{Salis_PRB89_45304_14} We attribute the origin of this discrepancy to the different symmetry of the SO-interaction studied in each case.

To simulate $g(T,E_z)$, we have assumed that $\gamma=17$~eV\AA$^3$, $r_{41}=6$~e\AA$^2$ and $d_\mathrm{eff}=28.6$~nm ($d_\mathrm{eff}$ takes into account both the QW thickness and the penetration length into the barriers) from our previous calculations of Ref.~\onlinecite{PVS261}. The initial carrier density profile, $n(r,0)$, is a 2D gaussian function with $w_0=3.6~\mu$m, in agreement with the measured FWHM of the carrier density at $t=0$. $n$ and $s_z$ evolve according to Eqs.~\ref{Eq_2Ddiff}, \ref{Eq_szSimulation} and \ref{Eq_angle}, with $D_{eff}=98$~cm$^2$/s for $t<1$~ns and $D_a=45$~cm$^3$/s for $t>1$~ns, as estimated from the slope of $w_a^2$ in Fig.~\ref{charge_wa2vstime} at each time interval. The solid lines in Figs.~\ref{charge_dynamics}, \ref{spin_dynamics} and \ref{spin_comparison} display the calculated spatial profiles for $n$ and $s_z$ at the corresponding time delays, showing a reasonable agreement with the experiment. For $E_z$ away from the SO-compensation, the reduced width of $s_z$ with respect to $n$ is due to the coherent precession of the spin vector around $\mathbf{\Omega}_\mathrm{SO}$. When $E_z\approx E_z^c$, then $g(T,E_z^c)=0$, the spin precession is suppressed, and therefore the FWHM of $s_z$ and $n$ become similar.

In the calculation, we have taken into account neither the cubic terms in $k$ of $\mathbf{\Omega}_D$, nor correction terms related to the slightly tilt of the substrate surface away from the [111] direction. These additional contributions introduce out-of-plane SO-field components and, most important, they break the symmetry between $\mathbf{\Omega}_D$ and $\mathbf{\Omega}_R$. As a consequence, the in-plane $\Omega_\mathrm{SO}$ does not cancel simultaneously for all the electrons in the ensemble, but only for a certain fraction, thus avoiding the extension of the measured $s_z$ profile to fully equal that of $n$ at $E_z^c$, cf. Fig.~\ref{spin_comparison}(b).

The fits of the temporal decay of $s_z$ by Eq.~\ref{Eq_szSimulation} yields the dependence of $\tau_s$ on $E_z$ and on the laser power shown in Fig.~\ref{spin_summary}. The dashed and dotted lines show, for comparison, the calculated DP dephasing lifetime for out-of-plane and precessing spins in an homogeneous spin ensemble.\cite{PVS261} As expected, $\tau_s$ has a maximum at $E_z^c\approx18$~kV/cm, where it fulfills $\tau_s\gg\tau_r$, and decreases as the electric field moves away from SO-compensation. Finally, we would like to remark that, for $E_z>20$~kV/cm, $\tau_s$ lies below $\tau_r$, as expected from the behavior of the time-integrated $\rho_z$ discussed in Fig.~\ref{spin_pol}.

\section{Summary}\label{Sec_summary}

We have shown that the application of a transverse electric field allows the transport of out-of-plane spin polarized electrons in an intrinsic GaAs (111) QW over distances exceeding 10~$\mu$m. We attribute the long transport distance to the compensation of the in-plane Dresselhaus SO-interaction by the Rashba one generated by the electric field, which cancels the precession of the spin vector around the SO-field during the radial expansion of the photogenerated \textit{e-h}~ ensemble. At SO-compensation, the main mechanism limiting the transport distance of the spin-polarized electrons is their recombination with holes, which takes place in typically a few nanoseconds. The favorable properties for spin transport of GaAs (111) QWs make them an excellent platform for further studies of the spin dynamics, as well as for spintronics applications.

\section*{Acknowledgements}
We thank Dr. Ramsteiner for useful discussions as well as M. H\"oricke and S. Rauwerdink for MBE growth and sample processing. We gratefully acknowledge financial support from the German DFG (priority program  SSP1285).

redpajama_set_name: RedPajamaArXiv


text:
March 2019 2018 Canadian Book Publishing Diversity Baseline Survey Report / accessible format
July 2018 The Canadian English-Language Book Publishing Industry Profile
December 2017 Net Benefit: Canada's Policy on Foreign Investment in the Book Industry
March 2017 Digital Trends and Initiatives in Education: The Changing Landscape for Canadian Content
January 2015 Public Opinions on the Value of Books in the English Language Book Sector, Summary Report
June 2012 Consultation on K to 12 Educational Publishing in Canada
2018 Canadian Book Publishing Diversity Baseline Survey
In recognition of the under-representation of Indigenous and racialized peoples in the Canadian publishing industry, the ACP's Diversity and Inclusion Working Group conducted a baseline survey to gather information on the composition of Canadian publishing workplaces. The survey establishes a baseline of the Canadian publishing industry and aims to identify challenges and opportunities with respect to building diverse and inclusive workplaces.
Download the 2018 Canadian Book Publishing Diversity Baseline Survey Report or in an accessible format.
The Canadian English-Language Book Publishing Industry Profile, 2018
Nordicity was engaged by the Association of Canadian Publishers (ACP) to conduct an economic impact and industry profile study of the Canadian English-language publishing industry. The purpose of this study is to establish baseline indicators of the size, structure and economic impact of the industry.
Download The Canadian English-Language Book Publishing Industry Profile, Nordicity, 2018
Net Benefit: Canada's Policy on Foreign Investment in the Book Industry
ACP commissioned this report as a longitudinal study of Canadian government policy on foreign investment in the book industry. The report focuses on the policy's current iteration, the Revised Foreign Investment Policy in Book Publishing and Distribution (1992). It examines the policy's implementation by successive governments over the past 25 years, summarizes the resulting impacts on the domestic book industry, and analyzes the policy's effectiveness in achieving its objectives. The report concludes with broad observations about the policy's use and abuse by both Conservative and Liberal governments in the past.
Download Net Benefit: Canada's Policy on Foreign Investment in the Book Industry, Roy MacSkimming, 2017
Digital Trends and Initiatives in Education: The Changing Landscape for Canadian Content
The Association of Canadian Publishers commissioned this report to better understand the digital trends and initiatives in education and how these trends and initiatives are impacting the acquisition ans use of Canadian content in the K-12 and post-secondary sectors.
Download Digital Trends and Initiatives in Education: The Changing Landscape for Canadian Content, by Susan Howell and Brian O'Donnell, March 2017.
Public Opinion on the Value of Books in the English Language Book Sector
The Book Strategy Group, an ad hoc committee representing the interests of Canadian writers and publishers, commissioned research to reveal current attitudes of English-speaking Canadians about the cultural and economic value of written works. The research explores matters of pricing, copyright law, file-sharing, ownership and lending models, as well as views on Canadian content, and assessments of knowledge and valuation of self-published books and traditionally published books. This research will be used to provide direction to the book industry in its efforts to better engage key influencers and to increase the sustainability and competitiveness of Canadian publishers and writers.
Five documents comprise the research:
Report on Usage and Value
Marketing, Library Usage, Illegal Downloading and Publishing
Public Opinion on the Value of Books in the Education Book Sector
Appendix Material: Consultation Instruments
Book Study Group members: Access Copyright, Association of Canadian Publishers,Canadian Educational Resources Council, Canadian Publishers' Council, Literary Press Group of Canada, Professional Writers Association of Canada, The Writers' Union of Canada.
We acknowledge the financial support of the Canada Council for the Arts and the Ontario Media Development Corporation.
Consultation on K to 12 Educational Publishing in Canada
Download Consultation on K to 12 Educational Publishing in Canada, by Glenn Rollans and Simon de Jocas, 2012.

redpajama_set_name: RedPajamaCommonCrawl


text:
Thomas Tippett (10 July 1904 – 1997) was an English footballer who played as a forward for Middlesbrough, Craghead United, Newcastle United, Doncaster Rovers, Rochdale, Port Vale, and West Ham United.

Career
Tippett played for Twizzell United, Middlesbrough, Craghead United (in three spells), Newcastle United and, after having trials with Stoke City and Grimsby Town, joined Doncaster Rovers and then Rochdale. He joined Port Vale in June 1931. He scored eight goals in 31 Second Division games in the 1931–32 season, but was criticized for his lack of goals. He fell ill in August 1932 and failed to regain his first team spot, scoring three goals in only nine league and cup games in the 1932–33 season. He left The Old Recreation Ground and transferred to West Ham United in May 1933.

Career statistics
Source:

References

1904 births
1997 deaths
Footballers from Gateshead
English footballers
Association football forwards
Middlesbrough F.C. players
Craghead United F.C. players
Newcastle United F.C. players
Doncaster Rovers F.C. players
Rochdale A.F.C. players
Port Vale F.C. players
West Ham United F.C. players
English Football League players

redpajama_set_name: RedPajamaWikipedia


A crystal pendulum can be used to receive answers from the crystal devas. The pendulum acts as a receiver and transmitter of the guidance. As the pendulum moves, you gain answers in response to questions. It is best suited to use to answer 'yes' or 'no' questions. You can request the pendulum to move in a certain direction to indicate the answer. Crystal pendulums can also be for healing, cleansing and balancing chakras, and cleansing the energy or dispelling negativity in a room/space. To heal a part of the body or to cleanse a chakra hold the pendulum above the body part/chakra and request the crystal deva to heal the body part or cleanse the chakra. The main criteria for receiving correct answers is to have a silent and open and doubt free mind. Any inclination towards an answer will affect the movement of the pendulum. To use the pendulum, hold the top bead at the top of the chain between your thumb and forefinger and put forth the question/request.
A golden colored metal vibhuti holder. Can be used to carry vibhuti.


text:
Sherman County (Oregon)
Catholic Church Catholic Catholicism -2 -98 -76.6%
Christian Churches and Churches of Christ Evangelical Protestant Baptist 0 -6 -14.6%
Conservative Baptist Association of America Evangelical Protestant Baptist 0 --- ---
Southern Baptist Convention Evangelical Protestant Baptist 0 -16 -28.6%
Presbyterian Church (U.S.A.) Mainline Protestant Presbyterian-Reformed 0 -43 -38.1%
United Methodist Church, The Mainline Protestant Methodist/Pietist 0 -10 -7.6%
Totals: -2 -173 -36.9%
The population of Sherman County, Oregon was 1,918 in 1990; in 1980 it was 2,172. The total population changed -11.7%. The adherent totals of the religious groups listed above (469) included 24.5% of the total population in 1990.
The population of Sherman County, Oregon was 1,765 in 2010; in 2000 it was 1,934. The total population changed -8.7%. The adherent totals of the religious groups listed above (303) included 17.2% of the total population in 2010.


text:
New battery research centre to be set up at Muenster University
(Nanowerk News) A new battery research centre is to be set up at the Westphalian Wilhelms University in Münster. The aim of the MEET (Münster Electrochemical Energy Technology) research project, headed by Prof. Martin Winter and Dr. Gerhard Hörpel from the Institute of Physical Chemistry, is to make electrochemical energy storage – first of all and primarily lithium-ion technology – more competitive in North Rhine-Westphalia and Germany as a whole. This will now be done by stepwise building up an Institute of Material Research at WWU.
The Ministry of Innovation, Science, Research and Technology of the state of North Rhine-Westphalia is funding the project to the amount of €5.5 million for the coming three years. Münster University is contributing €7.5 million. Further funding is coming from the North Rhine-Westphalian Ministry of Economic Affairs and Energy as well as the German Federal Ministry of Economics and Technology.
The medium and long term aim of the MEET Centre is to provide the technology for innovative materials for electrochemical electricity storage, with a markedly better cost-performance ratio and improved safety for both stationary and automotive applications. "Against a background of an enormous increase internationally in the importance of electrical energy storage," says Dr. Hörpel, "and particularly in our national electromobility and energy efficiency programmes, the planned research centre will bring together in one place the requirements for scientific basic research and industrial applications."
The University of Münster has strengths – its long-standing interdepartmental competence in materials sciences and analytics, as well as the competence in applied energy materials research and development newly acquired through the endowed Professorship for Applied Materials Sciences for the Storage and Conversion of Energy – which will be integrated and deepened in the MEET concept. As a result, the potential for synergies will be exploited to the full. "With the introduction of MEET as an essential link in the chain, and one which was hitherto missing," says Dr. Hörpel, "the gap will be closed between basic research and research commisioned by industry in the field of electrochemical storage technologies. And it will be happening at what is currently the most promising place in Germany in this field – Münster.
The prospective completion date for the MEET battery laboratory – the "core" of the MEET battery centre, in which new battery materials will be developed and battery prototypes will be produced – is autumn 2010.
Source: Westfälische Wilhelms-Universität Münster
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Lead halide perovskites are not ferroelectric - so why are they so good for solar cells?
Tougher glass using nanoparticles
Recent nanobook publications overview
Tiny vibration-powered robots are the size of the world's smallest ant
Wireless microengine made from a twisted fibre
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Scientists create predictive model for hydrogen nanobubble interaction in metals
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2D perovskite materials found to have unique, conductive edge states
Artificial intelligence designs metamaterials used in invisibility cloaks
'Smart' metamaterial textiles boost connectivity between wearable sensors by 1,000 times
DNA replication machinery captured at atom-level detail
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Possibilities of the biosimilar principle of learning are shown for a memristor-based neural network
Carbon nanotube films enable method to recycle waste heat
...more nanotechnology research news


text:
RODRIGUEZ READY FOR WOLAK REMATCH ON DECEMBER 3RD AT MADISON SQUARE GARDEN
CATSKILLS, NEW YORK (November 10, 2011) - With just under a month before the biggest fight in his career, Joe DeGuardia is happy to report that Star Boxing's Delvin Rodriguez is right on schedule with his preparation for his much anticipated rematch with Pawel Wolak (29-1-1, 19 KO's) which is part of the Miguel Cotto - Antonio Margarito HBO Pay Per View card at Madison Square Garden that will take place on December 3rd.
Rodriguez and Wolak engaged in what many are calling the leading candidate for fight of the year that took place on July 15th. Both guys stood their ground, showed tremendous courage and thrilled the sold out crowd at the Roseland Ballroom in a bout that was a draw. Each guy claimed victory and on December 3rd they will get a chance to prove who is better.
Rodriguez (25-5-3, 14 KO's) has had a smooth training camp as he is secluded in the Catskills.
"Everything has been smooth, on point and intense", said Rodriguez.
Rodriguez believes that the familiarity and his own versatility will be the difference this time around.
"I know what he brings to the table. He is a brawler and he can't change that. I can do different things in the ring and I know that will be the difference"
"These two styles go together and this will be another exciting fight"
Rodriguez of Danbury, Connecticut loves the fact that this fight has become an East Coast rivalry with the New Jersey resident and it's only fitting that this showdown will take place at the Mecca of boxing.
"Because of the first fight, people on the East Coast are treating this like the main event. I have worked so hard to get to this point. This is even bigger then my world title fights because it's my time to show that I belong."
"This is such a big card and when I win this fight, I will show the people that I deserve to be mentioned with all the names at the top of the division. It's great that the main event is Cotto and Margarito because when I win it could definitely put me in position to fight the winner of that fight and the combination of all that is what motivates me"
The Delvin Rodriguez-Pawel Wolak fight is part of the Miguel Cotto-Antonio Margarito II world championship telecast, which begins at 9 pm (EST)/6 pm (PT). It will be produced and distributed live by HBO Pay-Per-View and will be available to more than 292 million pay-per-view homes. The telecast will be available in HDTV for those who can receive HD. HBO Pay-Per-View, a division of Home Box Office, Inc., is the leading supplier of event programming to the pay-per-view industry.
Tickets for the Madison Square Garden card are priced at $600, $400, $300, $200, $100 and $50. They can be purchased at the Madison Square Garden box office, online at www.thegarden.com and all Ticketmaster outlets.


Martial Arts Palm Beach Gym isn't just a safe, clean and fun environment to learn jiu jitsu… It's a FAMILY!
At Martial Arts Palm Beach Gym, we take pride in the fact that our students not only obtain the knowledge they need to progress in the sport of Brazilian jiu jitsu – but get to do so in a fun and family-like atmosphere! The instructors are dedicated to helping people of all ages and skill levels learn "The Gentle Art". Whether you are training for fun, like to compete, as a hobby or just looking for a new way to stay fit, Martial Arts Palm Beach Gym could be the best fit for you.
Come in and try any or all of our world class programs for one week FREE. We proudly offer world-renowned instruction in the art of Brazilian Jiu-Jitsu (Gi) and submission grappling (No Gi). We have classes for Kids, Beginners, Intermediates, and Competition as well as courses in self defense and private instruction.
Ours is a wholesome and fun programs are designed for the entire family and for individuals who seek a positive and supportive environment. Our programs include lessons in life skills, anti-bullying, physical fitness, and body control.
Shawn's journey to becoming a black belt in Brazilian Jiu Jitsu has been a long one – with plenty of stops along the way. Trying his hand at karate, high school wrestling and tae kwon do along the way – he ended up in the fast-paced, high profile world of professional wrestling. While professional wrestling was fun – it didn't quench the competitive fire inside. Then he discovered Brazilian Jiu Jitsu. BJJ quickly became a passion and he put 100% of his energy into learning as much as he could. His dedication would pay off, as after 8 years, a lot of mat time and a World Championship at Brown Belt – Shawn received his black belt in 2014 under Master Manoel Soares.


text:
package com.amazonaws.services.cloudfront.model;

import javax.annotation.Generated;

/**
 *

 * This operation requires a body. Ensure that the body is present and the Content-Type header is set.
 *

 */
@Generated("com.amazonaws:aws-java-sdk-code-generator")
public class MissingBodyException extends com.amazonaws.services.cloudfront.model.AmazonCloudFrontException {
    private static final long serialVersionUID = 1L;

    /**
     * Constructs a new MissingBodyException with the specified error message.
     *
     * @param message
     *        Describes the error encountered.
     */
    public MissingBodyException(String message) {
        super(message);
    }

}

redpajama_set_name: RedPajamaGithub


Retina Center of Elk Grove, Inc.
To better serve our patients and referring doctors south of Sacramento, we welcomed the addition of our Elk Grove office in 2009. The office has easy access from Highway 99 and is equipped for advanced diagnostic testing and in-office procedures. Ample parking and a ground level location make the office highly accessible for all of our patients.
Our Elk Grove office treats many eye diseases such as macular degeneration, retinal vein occlusion, and retinal tears. We also provide comprehensive diabetic eye care, including the treatment of diabetic macular edema and both nonproliferative and proliferative diabetic retinopathy.
Elk Groves's in-office retinal procedures include fundus photography, retinal angiography, high resolution spectral domain optical coherence tomography (SD-OCT), ocular ultrasound, retinal laser, and intravitreal injections.
All of our offices can evaluate patients for retinal surgery. In addition, postoperative care is done in our offices. We offer retinal surgery consultations for retinal detachment, macular pucker, macular hole, diabetic retinopathy, vitreous hemorrhage, and vitreomacular traction.


text:
Anthony A. Peguero
Fellowships, Recognitions, and Awards
Laboratory for the Study of Youth Inequality and Justice (YIJ)
Fellowships, Recognition, and Awards
2016–Senior Fellowship, Institute for Society, Culture and Environment (ISCE), Virginia Tech
2013–2014, Fellowship. W.E.B. Du Bois Fellow, National Institute of Justice (NIJ).
2007, 2008, Fellowship. Criminal Justice Research Center, Racial Democracy, Crime and Justice Network (RDCJN), The Ohio State University and the National Science Foundation.
2006, Fellowship. Alliances for Graduate Education in the Professoriate (AGEP) & Preparing Future Faculty (PFF). Howard University. Washington, D.C.
2004, Fellowship. The National Center for Education Statistics (NCES). Washington, D.C.
2017–Current, Board Member, American Society of Criminology (ASC), Crime & Justice Research Alliance (CJRA)
2016–Current, Member, National Science Foundation (NSF): Sociology Senior Panel
2009–Current, Advisor to the Cartoon Network's Campaign against School Bullying/Violence
2015–2017, Executive Counselor, American Society of Criminology (ASC) Division on People of Color and Crime (DPCC)
2014–2016, Standing Review Panel on Research and Evaluation on Justice Systems, National Institute of Justice (NIJ).
2015–2016, Member, National Science Foundation (NSF): Sociology Dissertation Panel
2013–2015, Member, The Annie E. Casey Foundation, Juvenile Justice Strategy Group
2013–2015, Co-Chair, American Society of Criminology Division on People of Color and Crime (DPCC)
2018 Academy of Criminal Justice Sciences (ACJS), Minority and Women's Section, Becky Tatum Excellence Award.
2018 Virginia Tech College of Liberal Arts and Human Sciences, Excellence in Research and Creative Scholarship Award.
2014 Academy of Criminal Justice Sciences (ACJS), Juvenile Justice Section, Tory J. Caeti Outstanding Young Scholar Award.
2013 American Society of Criminology (ASC) Division on People of Color and Crime (DPCC) Coramae Richey Mann Award
2006 First Place Research Award. University of Miami, Citizens Board Research Creativity Forum.
2004 Outstanding Teaching Assistant Award. University of Miami, College of Arts and Sciences, Department of Sociology.


text:
Michael "Mike" Robertson (Edmonton, Alberta, 26 de fevereiro de 1985) é um snowboarder canadense. Robertson foi medalhista de prata do snowboard cross nos Jogos Olímpicos de Inverno de 2010 em Vancouver.

Ligações externas

Naturais de Edmonton
Snowboarders do Canadá
Snowboarders nos Jogos Olímpicos de Inverno de 2010
Medalhistas nos Jogos Olímpicos de Inverno de 2010


text:
Services and Sectors
Mahmood Samy Naib
msnaib@concordiacapital.org
NAIB, MAHMOOD SAMY
Chairman International Advisory Board
Mr. Naib has over 30 years of experience in the investment industry in North America, Europe, Asia and MENA regions. Since graduating from U.C. Berkeley in 1990, Mr. Naib has worked with leading international and regional firms in servicing leading blue-chip clients like Citigroup, Bank of America, Industrial Commercial Bank of China, Dubai International Financial Centre and others on their real-estate development portfolios.
In the past 14 years, in his roles as a Chief Development Officer at Abu Dhabi Investment House and Managing Director of Mena Gulf Investments, he has led the initiative to expand development funds beyond the traditional sectors and has successfully diversified key funds geographically. Also, he has been instrumental, over the years, in instituting multi-disciplinary tracking systems to achieve investment fund's expected returns, meet agreed exit deadlines, keep track of ESG and systematically measure funds social impact.
Mr. Naib has served, since 2007, as an advisor to many regional and national governments on their sovereign development funds. He has also served on advisory boards and board of directors of a number of companies in the GCC, Europe and North America.
Gran Via, 19-21 2nd & 3rd Floor, 48001 Bilbao, Spain
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Mississippi Blood Services (MBS) is a not-for-profit blood service, founded in 1979. Our mission is to provide a safe and adequate supply of voluntarily donated blood and blood components for patients in hospitals and to offer related services to our hospitals and other medical facilities.
MBS is the only FDA licensed blood center headquartered in Mississippi, created to manage our state's blood supply. We service hospitals across the state.
MBS is licensed by the Food and Drug Administration (FDA), accredited by the American Association of Blood Banks (AABB), a founding member of Blood Centers of America, Inc. (BCA/hemerica), a member of America's Blood Centers (ABC), and a member of the South Central Association of Blood Banks (SCABB).
In 1975, through the initiative of 26 civic clubs, Mississippi Regional Blood Center was formed. This initiative, along with a $400,000 federal grant provided start-up funding for the new blood center, with the stipulation that the center offer its services to hospitals and patients throughout Mississippi.
In November 1979, Mississippi Blood Services, Inc., was created through the consolidation of Family Blood Assurance Program and Mississippi Regional Blood Center.


Cause. The main reasons for obesity in dogs is an excess of calories and lack of physical activity. Endocrine problems, such as diabetes, hypothyroidism and Cushing's disease, can result in weight gain but are rare causes for obesity.
Diagnosis. A physical examination and thorough history help identify patterns that lead to weight gain. A blood test is frequently recommended to rule out an underlying disease.
If the examination and blood test are normal, your dog's eating habits will be assessed. What kind of dog food does your pet eat? When and how much? Is your dog given treats and table food? How much exercise does your dog get each day?
Going on a diet. Just cutting out table food and treats may work sometimes, but more often a therapeutic diet with exercise is needed. An overweight dog is at higher risk for diabetes, arthritis and becoming obese.
Stick to the plan. Hard as it might be to withhold the treat or the tidbit from the table, owners must be willing to stick to the plan. Weight must be monitored frequently and the dog's diet readjusted as needed. Many dogs require as long as a year to reach their target weight. As with humans, nutritious food in the proper quantity and exercise are important for pets to have a long and healthy life.
Rachael Ray Show: Is Your Pet Overweight?


WEST BAY - WEST OF TRAIL, SARASOTA - Homes Available!
West Bay is a private, gated enclave located in Sarasota's very desirable West of Trail area. This intimate enclave of just four single-family homes will feature clean Coastal and West Indies architectural styling, open floor plans, three car garages, central paver driveway, lush tropical landscaping, lagoon tropical pools and spas and more. Anticipated home completion in Spring 2019.
JUST ONE OPPORTUNITY AT WEST BAY REMAINS. Please call us at 941-328-3272 to learn more.


text:
by: supriya kashyap
Breakthrough in Lung cancer treatment: Scientists may Predict post operative relapse
Tracking unstable chromosomes helps predict lung cancer's return
Scientists have found that unstable chromosomes within lung tumours increases the risk of cancer returning after surgery, and have used this new knowledge to detect relapse long before standard testing. These are the first findings from the Cancer Research UK-funded TRACERx lung cancer study, published in the New England Journal of Medicine and Nature.
TRACERx is the first study to look at the evolution of cancer in real time and immense detail. Researchers followed patients all the way from diagnosis through to either disease relapse or cure after surgery, tracking and analysing how their cancer developed.
Professor Charles Swanton, lead researcher based at the Francis Crick Institute in London, said: "The TRACERx study is Cancer Research UK's single biggest investment in lung cancer, and for the first time we've revealed new insights into how tumours evolve and evade treatment, a leading cause of cancer death.
"We believe that this invaluable data generated during TRACERx will be seized upon by research teams across the world, helping us to answer more questions about lung cancer biology. We've only scraped the surface in terms of what is possible by looking at tumour evolution in such detail."
In one study published in the New England Journal of Medicine, scientists analysed tumours from 100 non-small cell lung cancer (NSCLC) patients. They found that unstable chromosomes are the driving force behind genetic diversity within tumours.
They also showed that patients with a high proportion of unstable chromosomes in their tumour were more than four times more likely to have their cancer return, or die from their disease, within two years.
This is because genetically diverse tumours are more likely to evolve, spread and become drug resistant, making a patient's cancer much harder to treat.
Dr Mariam Jamal-Hanjani, lead author based at the UCL Cancer Institute, said: "Determining the relationship between diversity within tumours and patient survival is one of the primary goals of TRACERx, so to find evidence for this so early on in the study is really encouraging.
"We've also identified what causes lung cancer to advance, providing us with insight into the biological processes that shape the evolution of the disease."
Armed with this discovery, researchers conducted a second study, published in Nature, to investigate whether this genetic diversity could be tracked clinically.
Using blood samples from 96 of the 100 patients, they demonstrated that the patchwork of genetic faults present in non-small cell lung cancer, could be monitored using bits of DNA in the blood that have broken off from a tumour (circulating tumour DNA).
They then analysed blood taken from 24 patients after surgery for NSCLC, and accurately identified more than 90 per cent of those destined to relapse up to a year before clinical imaging could confirm the disease's return.
This finding opens up numerous opportunities for new drug trials in lung cancer to try to prevent relapse.
Monitoring benefit from chemotherapy after surgery is not currently possible as there are often no clinical signs of disease.
With this in mind, the team also compared circulating tumour DNA levels immediately before and after chemotherapy was given to patients following surgery.
When levels of tumour DNA in the blood were not reduced following chemotherapy, the disease returned, suggesting that at least part of the tumour had become resistant to treatment.
The results provide a new means to monitor treatment after surgery, and point to an avenue for new treatments to target parts of the tumour that are resistant to existing approaches.
Dr Christopher Abbosh, lead author on the circulating tumour DNA study, based at the UCL Cancer Institute, said: "In the future patients could be offered personalised treatments that target parts of the cancer responsible for relapse following surgery.
"Using circulating tumour DNA we can identify patients to treat even if they have no clinical signs of disease, and also monitor how well therapies are working.
"This represents new hope for combating lung cancer relapse following surgery, which occurs in up to half of all patients."
Professor Karen Vousden, Cancer Research UK's chief scientist, said: "Lung cancer causes more than one in five of all cancer deaths in the UK and survival has only improved fractionally in the last 40 years. Understanding these highly complex processes is enormously challenging and the contribution made by both of these studies is an important step in the right direction.
"These findings could also help us to identify how lung cancers respond to therapy, building a bigger picture of the disease and potentially pointing the way to developing new treatments and, crucially, saving more lives."
TRACERx involves the collaboration of more than 225 researchers and clinicians based at 19 centres across the country and is also supported by the Francis Crick Institute, UCL Cancer Institute, University College London Hospitals Biomedical Research Centre, The Royal Society, Achilles Therapeutics, illumina, Natera and Rosetrees Trust.
Sam Howard, Chief Executive of Rose trees Trust, said: "Rose trees Trust is delighted to have supported Professor Swanton and the TRACERx project from the outset. We always believed in the importance of this research, the team of outstanding researchers and its potential for human impact."
You can read the full Article by clicking on the link :
Mariam Jamal-Hanjani, Gareth A. Wilson, Nicholas McGranahan, Nicolai J. Birkbak, Thomas B.K. Watkins, Selvaraju Veeriah, Seema Shafi, Diana H. Johnson, Richard Mitter, Rachel Rosenthal, Max Salm, Stuart Horswell, Mickael Escudero, Nik Matthews, Andrew Rowan, Tim Chambers, David A. Moore, Samra Turajlic, Hang Xu, Siow-Ming Lee, Martin D. Forster, Tanya Ahmad, Crispin T. Hiley, Christopher Abbosh, Mary Falzon, Elaine Borg, Teresa Marafioti, David Lawrence, Martin Hayward, Shyam Kolvekar, Nikolaos Panagiotopoulos, Sam M. Janes, Ricky Thakrar, Asia Ahmed, Fiona Blackhall, Yvonne Summers, Rajesh Shah, Leena Joseph, Anne M. Quinn, Phil A. Crosbie, Babu Naidu, Gary Middleton, Gerald Langman, Simon Trotter, Marianne Nicolson, Hardy Remmen, Keith Kerr, Mahendran Chetty, Lesley Gomersall, Dean A. Fennell, Apostolos Nakas, Sridhar Rathinam, Girija Anand, Sajid Khan, Peter Russell, Veni Ezhil, Babikir Ismail, Melanie Irvin-Sellers, Vineet Prakash, Jason F. Lester, Malgorzata Kornaszewska, Richard Attanoos, Haydn Adams, Helen Davies, Stefan Dentro, Philippe Taniere, Brendan O'Sullivan, Helen L. Lowe, John A. Hartley, Natasha Iles, Harriet Bell, Yenting Ngai, Jacqui A. Shaw, Javier Herrero, Zoltan Szallasi, Roland F. Schwarz, Aengus Stewart, Sergio A. Quezada, John Le Quesne, Peter Van Loo, Caroline Dive, Allan Hackshaw, Charles Swanton. Tracking the Evolution of Non–Small-Cell Lung Cancer. New England Journal of Medicine, 2017; DOI: 10.1056/NEJMoa1616288
Charles Swanton et al. Phylogenetic ctDNA analysis depicts early stage lung cancer evolution. Nature, 2017; DOI: 10.1038/nature22364
Source: self


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text:
Q: Overloading subscription operator() or [] with no code repetition I have two versions of operator():
const A& operator(int x ,int y) const;
A& operator(int x ,int y);

But I don't know what would be the best way to avoid code repetition (because they essentially have the same logic).
I did read the awesome FAQ regarding operator overloading (and some other questions) but did not find answer.
EDIT_1: I've tried the suggestion that Skizz proposed but something like that does not quite work for me but maybe I've missed something:
Because this works while this does not compile giving the following error:
error: invalid initialization of reference of type 'int&' from expression of type 'const value_type {aka const int}'

A: If both methods 'essentially have the same logic' then surely they should both be marked const. If they do behave differently, should they be called the same thing?
What you need is a third, hidden method that does the common thing, like this:-
const A& operator(int x ,int y) const
{
  return Common (x,y);
}
A& operator(int x ,int y)
{
  return Common (x,y);
}
A& Common (int x, int y) const
{
   // common code
}

This takes advantage of the implicit non-const to const conversion. In the first method, the this object remains const in the call to Common but the non-const return value is converted to const. In the second, the non-const this object is converted to a const this object and the return object is unchanged.

A: If you have the data in question as shared/unique pointer, you are able to forward it to a common function:
class X {
    public:
    const A& operator () (int x ,int y) const {
        common(data, x, y);
        return *data;
    }

    A& operator () (int x ,int y) {
        common(data, x, y);
        return *data;
    }

    private:
    void common(std::shared_ptr<T>, int x ,int y) const;
    std::shared_ptr<A> data;
};

Now you are able to access the T* via data.get() which is 'T* get() const'.
(Note: I consider the common function a bad design)
You might do, also:
class X {
    public:
    const A& operator () (int x ,int y) const {
        common(x, y);
        return data;
    }

    A& operator () (int x ,int y) {
       // ... make mutations
       common(x, y);
       // ... make mutations
       return data;
    }

    void common(std::shared_ptr<T>, int x ,int y) const;
    T data;
};

Or actually, making the data mutable, if it is not breaking logical const:
class X {
    const A& operator () (int x ,int y) const {
        // ... make mutations on the mutable data, only
        return *lazy_evaluated_data;
    }

    A& operator () (int x ,int y) {
        const X& self = *this;
        self(x, y);
        return *lazy_evaluated_data;;
    }

    private:
    mutable T lazy_evaluated_data; // or a cache
};

A: Write a helper function and call it from both operators. You'll need to do some const_cast<...>(this) which can be ugly, but it's a common pattern.

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