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Back To Category Beetle
Violet Ground Beetle
Category: Beetle
Facts about Violet Ground Beetles, Scientific name for Violet ground beetle is Carabus violaceus". The Violet Ground Beetle is normally refered to as the rain beetle is a nocturnal beetle from the family Carabidae. The Violet Ground Beetle is among the larget beetle species in the United Kingdom as it measures about up to 1 1/8 inches (20 to 30 millimeters). The Violet Ground Beetle is also widespread in most parts of Europe and Japan. The Carabus violaceus are known to prefer woodlands and marshy area where there are plenty of small animals for them to prey on. These areas also include gardens. Other habitats that you will likely find the Violet Ground Beetle inhabiting are farmlands, towns, and grasslands. In general, this is a widespread species of beetle and is not limited to just a few habitats, such as water scavengers are.
Attributes of Violet Ground Beetle
Most people confuse the beetle with the Carabus Promlematicus. However, these two beetles have notable differences in their elytra. The elytra of Carabus violaceus unlike that of the Carabus Promlematicus are smoother and spot fewer ridges and dimples. Since the Violet Ground Beetle is nocturnal, you will commonly find it under stones and logs during the day. Although the Violet Ground Beetle is common throughout the year, most of them hibernate in the coldest seasons, only to come up when the temperatures are more conducive to them, warmer.
Violet Ground Beetle are large, shiny, black beetles with violet edges to their smooth, oval wing cases (elytra) and the thorax. Their name comes from the coloration of their metallic purple edges.
Feeding of Violet Ground Beetle
The Violet Ground Beetle is a predator and will therefore emerge at night to hunt for animals such as slugs and other smaller insects. Other animals often hunted by the Violet ground beetle include worms and snails. The larvae of the Violet Ground Beetle are carnivorous too, often feeding on snails, worms, and smaller insects like the adult beetles do. Unlike most common beetles that are known to destroy crops and trees, the violet ground beetle will never destroy a plant since it is a predator. Its feeding characteristic is often an advantage since it feeds on a variety of small creatures that are often herbivores. This feeding behavior is particularly helpful to gardeners as the Violet Ground Beetle feeds on are organisms such as the slugs and snails whose presence in the garden can be very detrimental. The Grey field slug (Deroceras reticulatum) is known to be very destructive agricultural pest. The presence of the Violet Ground Beetles in a garden infested by these slugs, helps protect the crops as the beetles consume the slugs. The Violet Ground Beetle also feeds on other insects such as worms and weevils, animals that are known to cause a lot of trouble for farmers due to their destruction of food.
Reproduction of Violet Ground Beetle
Normally, the Violet Ground Beetle lay eggs in the soil or in places with accumulated organic matter. The larvae have elongated and relatively soft-bodied grubs. The grubs have three pairs of legs near the head end. The larvae, unlike the adult beetles are less active and will remain in the ground feeding on smaller invertebrates and their eggs.
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We've embraced our heritage as a traditional golfing tavern and put together a menu celebrating the best in pub fare. There's classics like beer battered fish & chips or steak pie and roast beef served in a giant Yorkshires on Sundays. Don't forget to save space for a sticky toffee pudding or cinnamon apple crumble.
If however you've opted to bring them, we've got you covered.
We couldn't be a respectable Scottish pub and not have an excellent selection of single malts, craft beers and cask ales. Try our our malt of the month and take a journey through Scotland with the national drink.
We've teamed up with The London Essence Co. to provide an exciting new range of perfect serves that we think are a hole in one.
Their team of mixologists has paired each London Essence Co. mixer with particular premium spirits. These combinations raise the bar in terms of taste and compatibility.
At the same time, we are eager to dispel the myths of mixology. With a little care, anyone can make a great G&T or Whisky & Ginger. No muddlers, mixing spoons, straws or shakers are required.
These are merely suggestions, of course. We encourage a spirit of experimentation, to suit personal tastes.
We take a lot of pride in our cask products and this is reflected in the time we spend cleaning and conditioning the lines. Ensuring every step of service is pristine you can rest assured you're getting the best pint in town. With a regular rotation of guest ales, check out the link to our blog below for what's on tap, we keep two of our favourites on tap at all times.
This session ale is one of our favourites, so much so that we stuck a badge on it and gave it its very own tap! Styled as a classic 80/- beer this dark and creamy beer gets its flavour from 5 different malts to give it hints of caramel and a soft hoppy finish. Flavourful but easy on the pallet, this beer lends itself to our food menu of hearty Scottish fare pairing nicely with our pie or chef's soup of the day.
Not quite an ale (it's a cider, obviously) and certainly not for the feint hearted, this bold beverage has a smooth, medium dry taste infused with hints of vanilla from the oak whisky barrels in which they mature. We recommend this to anyone looking for something unique in a cider market saturated with Swedish imports.
We couldn't be a respectable Scottish pub and not have an excellent selection of single malts. Make sure and keep an eye out for our malt of the week and if you're feeling adventurous try any of our malts in our classic Old Fashioned.
© The Golf Tavern 2019 – All Rights Reserved.


Information: The course recorder masterclass addresses teenage and adult recorder players, as well as students who would like to go musically and technically deeper into prepared compositions of free choice. Sometimes little hints and tricks are enough to be enable you to play a movement easier, more interesting and also more expressively. Addressed are especially teenagers who want to prepare for the solo contest "Jugend musiziert '19". Besides the private tutoring, music will be played collectively "just for fun".
Accompaniment will be provided by the cembalo player Nico Saakadze (co-coach at the Musikhochschule Münster).
Requirements: Please make sure to inform us which compositions you prepared and if you need a cembalo accompaniment.


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2015 OGU Reunion
On Saturday 26 September, the school played host to the annual OGU reunion lunch, attended by twenty five former pupils. Old girls once again travelled from all over the country with Cynthia Micheletti nee Robertshaw (BGGS 1950-1958), making the journey from Cape Town, over 9,000 miles, to meet up with her former school friends.
The spread of leavers ranged from as earlier as 1947, with Old Girl Ann Clegg (nee McDonald) who attended the school from 1942-47, right up to the 1980's.
A large group of ladies reminisced about their time at the school in the 1950's with many leaving in 1956 and 1957.
Members enjoyed meeting current pupils and taking a tour of the school, taking in the displays of pupils' work and special events and finally culminating in refreshments in the stunning library. A particularly favourite part of the school, the senior library still houses the beautiful Robert Thompson oak furniture and provided the perfect setting to catch up with old friends and peruse through the archive collections.
After the tour, the Old Girls were escorted to the dining room for a delicious lunch. See the gallery at the bottom of the page for more photo's of the 2015 reunion.
On Saturday 4 October, over fifty OGU members attended the annual Old's Girls Reunion lunch. This year saw the majority of Old Girls travelling from across the region, whilst Cynthia Micheletti nee Robertshaw (BGGS 1950-1958), once again made the journey from Germany.
A special 60 year reunion of the Upper Thirds of 1954 was well represented with many of the former pupils still firm friends after all these years. Additionally, a group of ladies who left in 1984 also celebrated a special reunion year – 30 years on.
Members were delighted to be met by current pupils and given a tour of the school, showing particular interest in the school archives and the old library with the beautiful Robert Thompson Mouseman oak furniture. The group of Old Girls, including the three 'Green' sisters; Jennifer, Sally and Katharine who left the school in 1968, 1970 and 1977 respectively, enjoyed looking through the archive of old photographs and school publications, and talking to members of the student leadership team.
Jane Tinker recognised many of her friends and classmates on one of the whole school photographs in the school gallery whilst Eveline Wilkinson (BGGS 1945-51) and Pat Smith nee Whitaker (BGGS 1944-50) reminisced about their form room G1, now used as a school office.
After the tour, the Old Girls were escorted to the dining room for a delicious lunch and the chance to catch up with old friends, some of whom had not seen each other for over 50 years. Everyone agreed that it had been a successful and memorable day.
See the gallery at the bottom of the page for more photo's of the 2014 reunion.
On Saturday 28 September, over fifty OGU attended the annual reunion lunch. Cynthia Micheletti nee Robertshaw (BGGS 1950-1958), who attends every year, traveled from Germany while Sue Sayles nee Wilkinson (BGGS 1963-1970) made a special journey from France.
Members were delighted to be met by current pupils and given a tour of the school, showing particular interest in the school archives and the old library. Rachel Killock nee Mason (BGGS 1953-60) and Gillian Haigh nee Dracup (BGGS 1953-60) (pictured above) were particularly thrilled to find themselves on a photograph in the school gallery.
Old Girls enjoyed looking through the archive of old photographs and school publications, and Beverly Hills nee White (BGGS 1962-69) recognised many of her friends in a 1968 edition of the school newsletter, The Chronicle.
After the tour, the old Girls were escorted to the dining room for a delicious lunch and the chance to catch up with old friends, some of whom had not seen each other for over 20 years.
On Saturday 29 September, over a hundred OGU members attended the Open Morning and the annual reunion lunch. Elizabeth Adkins (nee Cullingford) who left the school in 1958 came all the way from Chicago.
Miss Foulds, a former member of staff who joined BGGS in 1951, also attended and was thrilled to be reacquainted with so many of her former pupils.
On Saturday 1st October, over 80 OGU members travelled from as far away as Alaska, Germany and Norway as well as throughout the United Kingdom to attend the school open morning and annual OGU reunion lunch.
Elaine Wardell nee Burnell (BGGS 1950 – 1957) travelled from Alaska to proudly show her husband, daughter and granddaughter where she was educated.
Cynthia Micheletti nee Robertshaw (BGGS 1950-1958) who lives in Germany attends the reunion every year and Patience Lister (BGGS 1981-1988) who lives in Norway attended for the second year in a row.
Ex staff included Mrs Foulds who joined BGGS in 1951, Miss Marjorie Robinson who taught at BGGS from 1957 – 1985 and Miss Briggs who was an Old Girl of the school and already a long serving member of staff when she took over as Lady Royd Headmistress in 1959. She taught until 1987 and has kept in contact with the school ever since.
Members were delighted to receive their blue BGGS welcome bags containing details about the open morning activities, results and destinations, a copy of 'The Leader' – the school newsletter, their OGU lunch ticket and complimentary packets of Yorkshire Tea.
The OGU raffle raised £60 for OGU funds and prizes went to:-
1st prize – Hamper from Bettys, Mrs Hazel Greenwood (nee Brown) (BGGS 1953-1962)
2nd prize – BGGS Christmas Cake – Mrs Janet Laughlin (nee Shackleton) (OGU Secretary)
3rd prize – Fresh Flower Arrangement – Mrs Julie Green
Members commented on how wonderful the school looked and were delighted to be shown around the school by our present girls acting as tour guides. The food was delicious and everyone enjoyed catching up with friends, some of whom had not seen each other for over 20 years. The weather was glorious which all added to a most memorable day.
AGM Minutes 2015
Join the Old Girls' Union
Contact: E.Tucker
Email: etucker@bggs.com
Join us on LinkedIn:
Bradford Girls' Grammar School Alumnae OGU

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Photography and the representation of modernist architectural space: from the melancholy fragment to the colour of utopia
Green, Nigel (2007) Photography and the representation of modernist architectural space: from the melancholy fragment to the colour of utopia. PhD thesis, University College for the Creative Arts/University of Kent.
(12MB)
Green, Nigel
The questions that this project poses are centred on an examination of photography's realtionship to modernist architectural space. Polarising the melancholic and the utopian, the definition of photography is extended to include its manifestation across a number of diverse sites and processes. What is the connection between the processes and technology of photography and its representation of modernist space? How can these relatiionships inform and articluate a photographic practice.
Partial fulfilment for the Degree of Doctor of Philosopy in Arts and Communication.
This thesis has been digitised by the Library at the University for the Creative Arts (UCA) for the purposes of preservation and dissemination.
Academic content delivered in UCARO is made available for non-commercial research purposes only. Unless otherwise stated, content will be protected by copyright and for further use beyond research you will need to seek permission from the rightsholder (for example, author, publisher, artist).
architecture, photography


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Q: How to exclude logo's and icon in Google Search Queries? I'm using Google Wemaster Tool. I'm struggle having this unwanted search queries.
Japanese           English
電話 アイコン         Phone icon
電話 アイコン png     Phone icon png
電話PNG             Telephone PNG
アイコン 電話         Icon Phone
問い合わせ アイコン    Contact icon
Chinese
電話                Phone
电话                Phone

Arabi
هاتف png            Png phone
Macedonian
виза и мастеркард   Visa and MasterCard logo

What should I do to remove this keywords in my google search queries?

A: Provide good context for the image.
After adding alt text and title in the image, the unwanted search queries are gone.
https://support.google.com/webmasters/answer/114016?hl=en

redpajama_set_name: RedPajamaStackExchange


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Q: Place paragraph header above paragraph within flexbox I currently have a section that contains an image, an h2, and a paragraph. For the 768px+ media query, it takes a display: flex; to align left-right. However, this of course makes it so that the h2 is between the image and the paragraph, but I want the h2 to be sitting above the paragraph and left-aligned. I feel like I've tried a lot of different things so kind of at a loss at this point.

A: Without seeing your code, I'm kinda guessing here. But I think you want image > h2 > p below each other, and then image > H2/P next to each other in the media query.
If that's the case, it's just a matter of wrapping the h2 and p in their own div to control the flex direction at a certain width.

.wrapper {
  display: flex;
  flex-direction: column;
}
.text-wrapper {
  display: flex;
  flex-direction: column;
}

// Not sure what you want here, but changing the direction property should solve it
@media only screen and (min-width: 768px) {
  .wrapper {
  flex-direction: row;
  }
}

 Image

 Header

 Paragraph


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\section*{NOMENCLATURE}

\section*{Introduction}

\begin{figure*}[ht!bp]
\center
\includegraphics[width=\textwidth]{fig_intro}
\caption{Necks are ubiquitous in cellular membranes, and can be approximated by catenoid-like shapes. Here, we explore the relationship between catenoids and protein-induced spontaneous curvature and discuss the implications for the formation of necks. (a) The formation of necks by cellular membranes is critical for fission and fusion. A large variety of biological processes and molecular mechanisms are involved in the formation of necks; however, a common feature of these structures is that they share a catenoid-like shape. (b) Tomography slices and (c) fitted representative profiles at different stages of clathrin mediated endocytosis (CME). Red squares highlight catenoid-like neck shapes, scale bar is 100nm. (Adapted from \cite{avinoam2015}). (d) Mean ($H$) and Gaussian ($K$) curvatures (normalized with respect to neck height) at the neck of 105 CME pits, as a function of the invagination angle $\theta$. Light symbols are data points, dark symbols with error bars are average and standard deviation of 15 data points. Necks can be approximated as catenoids in the region where the mean curvature is close to zero.
(e) A catenoid belongs to the class of minimal surfaces, which have principal curvatures of opposite values at every point of the surface ($\kappa_1=-\kappa_2 $). As a consequence, the mean curvature $H=0$, and the Gaussian curvature $K<0$ everywhere.}
\label{fig:intro}
\end{figure*}

Neck-like structures are a necessary geometric intermediate for fusion and fission in cellular membranes and play important roles in membrane trafficking (both in endo- and exocytosis) and transport within the endomembrane system \cite{hurley2010, campelo2012, kukulski2012, messa2014}. Furthermore, the formation of necks is a critical step in the interaction of toxins and viral fusion proteins with cellular membranes \cite{mishra2008, schmidt2010, schmidt2013, martyna2017}. These structures are also observed in synthetic membrane systems such as in giant unilamellar vesicles subject to osmotic stress \cite{zhu2012, sanborn2013, ho2016}, lipid heterogeneities \cite{baumgart2003, baumgart2005}, protein insertion or crowding \cite{busch2015, snead2017}, and membrane-substrate interactions \cite{staykova2011}.
As shown in Fig.~\ref{fig:intro}(a), the mechanisms producing neck structures are as diverse as the underlying biological processes. Despite this diversity, their formation is subject to biophysical constraints, and most often requires bending the membrane in the presence of compositional in-plane heterogeneities. These membranes heterogeneities can be produced in many ways, resulting in a preferred mean curvature known as the spontaneous curvature \cite{zimmerberg2006, baumgart2011, lipowsky2013, jarsch2016, chabanon2017a}. The mechanisms inducing spontaneous curvature on the membrane can broadly be classified into five categories:  lipid asymmetry across the leaflets, hydrophobic insertion due to proteins, scaffolding due to proteins, oligomerization, and crowding due to proteins or other external moieties. The local value of spontaneous curvature that influences the formation of neck-like structures can then be interpreted as the combined result of several of these mechanisms.

The formation of a neck is a complex process that can involve a large number of curvature-inducing mechanisms in sequential and parallel manners. One of the best known examples is clathrin-mediated endocytosis (CME), where a membrane coat is initiated, producing a subsequent membrane invagination and vesicle formation through the dynamic coordination of more than 30 proteins such as clathrin, epsin, BAR domain proteins and dynamin \cite{cocucci2012, kukulski2012, shi2015}. The steps involved in neck formation is illustrated in Fig.~\ref{fig:intro}(b) and (c) where tomographic slices and membrane profiles of representative steps of CME are shown (Images and data in Fig.~\ref{fig:intro}(b-d) are adapted from \cite{avinoam2015}). The stage of endocytosis can be related to $\theta$, the maximum angle between the flat plasma membrane and the bud (Fig~\ref{fig:intro}(d)) \cite{avinoam2015}. As seen from Fig~\ref{fig:intro}(b-d), no neck is yet formed at early endocytic stages corresponding to $\theta<90^\circ$. However for $\theta$ between $90^\circ$ and $160^\circ$ the neck is characterized by a mean curvature close to zero, and a negative Gaussian curvature (Fig~\ref{fig:intro}(d)). Such geometrical properties are characteristic of minimal surfaces, of which a catenoid is a non-trivial example (Fig.~\ref{fig:intro}(e)). This strongly suggests that there exists a phase during CME, and likely most necking events, where the shape of the neck is well approximated as a catenoid \cite{kozlovsky2003, jiang2008, singh2012, mcdargh2016}.

In this work, we sought to understand how the spontaneous mean curvature interacts with the Gaussian curvature of catenoid-shaped membrane necks. At the continuum scale, the energy of a lipid bilayer is commonly described by the Helfrich energy \cite{helfrich1973, ou-yang1999, steigmann2003, lipowsky2013}.  Helfrich proposed an elastic strain energy for the lipid bilayer that depends on the mean and Gaussian curvature, to capture the bending effects. Because the bilayer is being modeled as a single manifold, a penalty for the mean curvature asymmetry is imposed by means of the spontaneous mean curvature, henceforth termed just `spontaneous curvature'. As a result, one can use this framework to ask, given a spontaneous curvature field, what is the resulting shape of the membrane? Such efforts have been used successfully in \cite{seifert1991, agrawal2009a, lipowsky2013, rangamani2014, hassinger2017} among others, leading to a good understanding of the role of the mean curvature and spontaneous curvature. However, the role of the Gaussian curvature on membrane physics is trickier to grasp. In most studies of membrane mechanics, the contribution of the Gaussian curvature is not significant because of the Gauss-Bonnet theorem \cite{kreyszig1991, frankel2011}, which states that the integral of the Gaussian curvature over a surface only depends on the variations of the boundaries and topology of this surface.  While this certainly means that the Gaussian curvature will not influence the energy of a system such as a closed vesicle, this is not the case, in general, for open boundaries or necks \cite{steigmann1999}. Particularly, in the case of minimal surfaces such as catenoids where the mean curvature is zero, the Gaussian curvature is the only contribution of the curvature tensor to the energy, and therefore plays a critical role in the determination of the equilibrium state of the system.

Motivated by these considerations, we ask the following questions: Given a catenoid-shaped neck connecting two reservoirs of curvature-inducing proteins, what is the spontaneous curvature field on this surface that minimizes the Helfrich energy? How is this spontaneous curvature field influenced by the neck radius? And finally, how can we modulate the field of spontaneous curvature in order to promote the necking process? To answer these questions, we use Helfrich energy of lipid bilayers \cite{helfrich1973} \red{augmented with membrane protein energy}, and conduct simulations to identify how the Gaussian curvature and the spontaneous curvature are related in catenoid-shaped necks.
In order to proceed, we adopt an inverse problem approach to membrane biomechanics. Traditionally, the steps involved in solving the shape equation resulting from the Helfrich model are (i) fixing the distribution of spontaneous curvature and the boundary conditions and (ii) determining the shape of the membrane from resulting mean and Gaussian curvatures. In contrast, our approach consists of (i) fixing the shape of the membrane (to a catenoid) and the boundary conditions, and (ii) solving for the resulting distribution of spontaneous curvature. We argue that once the spontaneous curvature is known, one can infer the local membrane composition from constitutive relationships for specific lipid-protein coupling. Accordingly, in all of this study, the fixed quantities are the mean and Gaussian curvatures, while the \textit{spontaneous curvature is the coordinate-dependent unknown variable} \red{through the protein density}.

\section*{Model and Methods}

\subsection*{Equilibrium model of elastic membranes with heterogeneous distribution of spontaneous curvature}

In this section, we provide a concise derivation of the generalized shape equation using a local force balance. (Additional details are provided in the Supplementary Material). This approach, initally  developed in \cite{steigmann1999, rangamani2013a, rangamani2014}, results in an equivalent model to the one obtained by variational considerations \cite{steigmann2003, agrawal2009a, agrawal2009}, but accounts for local inhomogenities on the membrane \cite{steigmann1999}.

We first summarize the assumptions under which our model is valid:
\begin{enumerate}
\item Length-scale separation: We consider membrane deformations that are much larger than the thickness of the bilayer, allowing us to treat the membrane as a \textit{thin elastic film of negligible thickness} \cite{helfrich1973}.
\item Time scale separation: We assume that the membrane deformations are much slower than the rate at which the energy is dissipated, allowing us to consider the membrane to be at \textit{mechanical equilibrium}
\item Incompressibility: Due to the high stretching modulus of lipid bilayers, we assume the membrane to be \textit{incompressible/inextensible}.
\item Free energy: Based on \textit{Helfrich model} of lipid bilayers \cite{helfrich1973}, we treat the lipid membrane as an elastic manifold for which the bending energy functional depends only on the local curvatures and compositional heterogeneities.
\item Spontaneous curvature: Due to the length-scale separation, the packing heterogeneities induced by heterogeneous membrane composition (lipid types, membrane proteins) cannot be explicitly represented. Instead, the effect of the bilayer composition on the preferred membrane curvature is taken into account by the \textit{spontaneous (mean) curvature} $C(\sigma)$, which depends on the local protein density ($\sigma$).
\red{
\item Protein contribution to the free energy: We assume that the presence of membrane bound protein contributes to the free energy through an additive term $A(\sigma)$ that account for protein enthalpic and entropic effects.
}
\item Homogeneous mechanical properties: We assume the mechanical properties of the membrane to be independent of the compositional heterogeneities. A discussion of the effect of varying membrane moduli can be found in \cite{hassinger2017}.
\item Inviscid lipid membrane: Due to the fluid characteristics of lipid membranes, we neglect any resistance to shear forces in the membrane.
\end{enumerate}

\paragraph*{Model development}

We start by expressing the local force balance on the membrane by the equation of mechanical equilibrium of an elastic surface $\omega$ subject to a lateral pressure $p$. This can be written in the compact form as \cite{steigmann1999}
\begin{equation} \label{eq:force_balance}
\bm{\sigma}_{;\alpha}^\alpha + p \mathbf{n} = \mathbf{0} \; ,
\end{equation}
where $\bm{\sigma}^\alpha$ are the stress vectors and $\mathbf{n}$ is the unit normal to the local surface. Here onwards, Greek indices range over ${1,2}$, and if repeated, are summed over this range. The semicolon indicates covariant differentiation. The stress vectors are further defined as
\begin{equation} \label{eq:Asig}
\bm{\sigma}^\alpha = \mathbf{T}^\alpha + S^\alpha\mathbf{n} \;,
\end{equation}
where $\mathbf{T}^\alpha$ are the values of the tangential stress vector field that depend on the energy per unit area of the membrane, and $S^\alpha$ is the contravariant vector field that contains the normal components of the stress vector \cite{steigmann1999, rangamani2013a}  (see Supplementary Material for details).

The most common model for the free energy density of lipid membranes is the Helfrich energy \cite{helfrich1973}. \red{We extended to account for the entropic contribution of membrane-bound proteins to the areal free-energy functional such as \cite{agrawal2011}
\begin{equation} \label{eq:Wdiff}
W(\sigma, H,K; \theta^\alpha)=k(\theta^\alpha)[H-C(\sigma )]^{2} + k_G(\theta^\alpha) K + A(\sigma ) \;,
\end{equation}%
}
Here $H$ and $K$ are the mean and Gaussian curvatures respectively. $k(\theta^\alpha)$ and $k_G(\theta^\alpha)$ are the bending and Gaussian moduli respectively, which in the general case can be dependent on the surface-coordinate $\theta^\alpha$. $C(\sigma)$ is the spontaneous (mean) curvature, which is determined by the local membrane composition, in this case the surface density of protein $\sigma$.  While it is certainly possible to propose an explicit function of $C(\sigma)$ on the protein density as is done in the Supplementary Material, we will for now, retain its general form.
\red{
Finally, $A(\sigma)$ is the contribution of the membrane-bound proteins to the free energy and $\sigma$ is the surface density of proteins.}

The local force balance of a membrane subject to the above energy functional results in normal and tangential stress balance equations, commonly referred to as the shape equation and the incompressibility condition respectively. Following the procedure in  \cite{steigmann1999, rangamani2013a} (see Supplementary Material), these are written in the general case of anisotropic membranes as
\begin{equation} \label{eq:hape}
\Delta \left[ k (H-C) \right] + 2H\Delta k_G - (k_G)_{;\alpha\beta} b^{\alpha\beta} + 2k(H-C)(2H^2-K) + 2H(k_G K - W(\sigma,H,K) ) = p + 2\lambda H \;,
\end{equation}
and
\red{
\begin{equation}\label{eq:incomp}
\nabla \lambda = -W_\sigma \nabla \sigma
-\nabla k (H-C)^2 - \nabla k_G K \;,
\end{equation}
where $\Delta(\cdot)$ and $\nabla (\cdot)$ are the surface Laplacian and gradient respectively, and $W_\sigma$ is the partial derivative of the free energy with respect to $\sigma$. By definition, $W_\sigma$ is the chemical potential associated the membrane proteins.}

Together, Eqs.~\ref{eq:hape} and \ref{eq:incomp} describe the equilibrium configuration of a lipid membrane subject to a distribution of protein density $\sigma$.
Additionally, the membrane must satisfy the existence of a tangential velocity field $u^\alpha$, such that the membrane incompressibility condition $u_{;\alpha }^{\alpha }=2Hw $ is respected ($w$ is the normal velocity of the membrane). But this velocity field is decoupled from the shape equation and tangential equation for an inviscid membrane \cite{rangamani2013a}. Therefore, the sufficient condition is the existence of the flow field. In the case of static surfaces, tangential flow fields are known to exist without affecting the shape of the surface and are studied in soap films and membranes \cite{bahmani2015}.

\paragraph*{Static distribution of curvature-inducing proteins on minimal surfaces}

Eqs.~\ref{eq:hape} and \ref{eq:incomp} link the membrane geometry of the membrane (through $H$, $K$ and the surface differential operators) to the protein density ($\sigma$) and therefore the distribution of spontaneous curvature $C(\sigma)$. Here we examine how a catenoid-shaped membrane influences $C$ by specializing Eqs.~\ref{eq:hape} and \ref{eq:incomp} to minimal surfaces.
Catenoids belong the to the mathematical family of minimal surfaces, which locally minimize their surface energy everywhere \cite{osserman1996, torquato2004, frankel2011}. These have been historically studied in the context of soap films and the formation of membrane tethers \cite{kreyszig1991, powers2002, frankel2011, goldstein2010} and more recently in the context of shapes adopted by organelle membranes \cite{snapp2003, terasaki2013, bahmani2015}.

Minimal surfaces are characterized by the property that the mean curvature
vanishes pointwise ($H=0$ everywhere on the membrane). Furthermore, as a first approximation, we consider membranes with isotropic mechanical properties ($k$ and $k_G$ are constants). Accordingly, in the absence of transmembrane pressure, the shape equation (Eq.~\ref{eq:hape}) reduces to a variable-coefficient Helmholtz equation for the spontaneous curvature
\begin{equation} \label{eq:hape_mini}
\Delta C(\sigma)-2KC(\sigma) =0 \;.
\end{equation}%
In view of the fact that the Gaussian curvature is determined entirely by the metric of the surface (Gauss' \textit{Theorema Egregium}), it follows that the spontaneous curvature on a minimal surface induces a distribution on any other such surface that can be obtained from it by an isometric map. This is the case for instance between catenoids and helicoids, provided that the boundary conditions follow the same mapping.

\red{Both the energetic contribution of the proteins $A(\sigma)$ and the local Lagrange multiplier $\lambda$ are now absent from the shape equation \ref{eq:hape_mini}, therefore uncoupling them from the incompressibility condition. Yet, any solution of Eq.~\ref{eq:hape_mini} is restricted to the condition that the balance equation \ref{eq:incomp} is satisfied. This latter condition is derived for minimal surfaces in the Supplementary Material, resulting in
\begin{equation} \label{eq:admiss_lambda}
\lambda (\sigma) =-[A(\sigma )+kC(\sigma )^{2}] + \lambda_0 \;,
\end{equation}
}
where $\lambda_0$ is a constant.

The system composed of Eqs.~\ref{eq:hape_mini} and \ref{eq:admiss_lambda}, can be further developed to explicitly depend on the local membrane composition, as shown in the Supporting Material. However, \red{explicitly defining $A(\sigma)$ and $C(\sigma)$} requires several simplifying assumptions on the type of curvature-inducing proteins, the relationship between spontaneous curvature and protein density, as well as on the protein-protein interactions. While this extra step can be conceptually insightful, it is of low practical interest in the absence of available experimental data to test this model. \red{
Furthermore, in the case of minimal surfaces, the uncoupling between the shape equation and the incompressibility condition allows us to treat the problem in term of $C(\sigma)$ without having to define the protein contribution to the membrane energy $A(\sigma)$.
}
For this reason, we choose to solve this model in the general case and discuss the results in terms of spontaneous curvature instead of protein density. Provided the knowledge of the explicit function for $C(\sigma)$ from experiments or such as the ones proposed in the Supplementary Material, one can map $\sigma$ from $C$.

\paragraph*{Boundary conditions and relation to membrane tension}

The shape equation for minimal surfaces (Eq.~\ref{eq:hape_mini}) now has a one-way coupling with the membrane tension. Therefore we can first solve Eq.~\ref{eq:hape_mini} for $C$ given a minimal surface of Gaussian curvature $K$. From a mathematical perspective, Eq.~\ref{eq:hape_mini} is a variable-coefficient Helmholtz equation for $C$, and two boundary conditions either Dirichlet, Neumann, or of the mixed type \cite{rangamani2013a} can be prescribed. In this work, we consider Dirichlet conditions at the minimal surface boundaries. The physical justification for this choice is that necks are connecting larger membrane reservoirs on each sides, which serve as sources for curvature-inducing proteins (see Fig.~\ref{fig:cat1}(a)). Since the distribution of $C$ on a minimal surface should satisfy the admissibility conditions for $\lambda$ (Eqs.~\ref{eq:admiss_lambda}), imposing Dirichlet boundary conditions for $C$ results in imposing the membrane tension $\lambda$ at the boundary satisfying Eq.~\ref{eq:admiss_lambda}. In fact, this condition provides a correspondence between spontaneous curvature and membrane tension everywhere on the surface.

It is important to note that the boundary conditions here should not be confused with boundary conditions between the protein inclusion and the monolayers, which have been studied in detail elsewhere \cite{aranda-espinoza1996, kim1998, gil1998}. In contrast to these studies, here we consider the spontaneous curvature of the whole bilayer, including the one induced by the protein inclusion. In this approach, we neglect any membrane thickness variation (see model assumption 1), and do not account for the specific location of the protein inclusion. The only boundaries we consider are the ones at the boundaries between the membrane minimal surface and the membrane reservoirs.

\subsection*{Model Implementation}

\paragraph*{Catenoids}

We consider a catenoid of height $h_0$ and neck radius $r_n$ such as the one depicted in Fig.~\ref{fig:cat1}(b). In axisymmetric coordinates, this surface can be parametrized by
\begin{equation}
r = r_n\cosh(z/r_n) \quad \text{with } z\in[-h_0/2; h_0/2] \;.
\end{equation}
We seek the distribution of spontaneous curvature along the arclength $s = r_n \sinh(z/r_n)$ in the axial direction. We choose the total arclength $L = 2r_n \sinh[h_0/(2r_n)]$, as the characteristic length of the catenoid.

The shape equation (Eq.~\ref{eq:hape}) involves two geometrical invariants of the surface: the mean and the Gaussian curvature. The mean curvature is zero everywhere on a catenoid; however the Gaussian curvature of a catenoid depends on $z$ and the neck radius as
\begin{equation} \label{eq:K}
K = -\left[\frac{1}{r_n \cosh^2(z/r_n)}\right]^2 = -\left[\frac{1}{r_n (1+(s/r_n)^2) } \right]^2.
\end{equation}
The Gaussian curvature of the catenoid is negative everywhere and is minimum (i.e. maximum magnitude) when $z=0$ or $s=0$ (Figs.~\ref{fig:cat1}(c) and \ref{fig:cat2}(b)). As the neck radius decreases, the Gaussian curvature at the neck decreases towards minus infinity, while it tends to zero away from the neck.

\paragraph*{Boundary conditions}

As noted above, we specify the spontaneous curvature at the boundaries with the following Dirichlet boundary conditions:
\begin{equation} \label{eq:bc}
C= \left\{
\begin{array}{l}
C_0 \quad \text{at the lower boundary} \\
C_1 \quad \text{at the upper boundary}
\end{array}\right. ,
\end{equation}
where $C_0$ and $C_1$ are prescribed.

\paragraph*{Implementation}

We write the dimensionless forms of Eqs.~\ref{eq:hape_mini} and \ref{eq:bc} using the total arclength of the symmetric catenoid $L$, and the reference value of spontaneous curvature at one of the boundaries $C_0$, respectively.  Accordingly, the geometric variables are scaled as $\bar{\theta}^\alpha = \theta^\alpha/L$, and $\bar{K} = KL^2$, while the spontaneous curvature is scaled as $\bar{C} = C/C_0$. Accordingly, the system can be written in its dimensionless form as
\begin{equation} \label{eq:hape_mini_nd}
\Delta \bar{C} -2\bar{K}\bar{C} =0,
\end{equation}
with the dimensionless boundary condition
\begin{equation} \label{eq:bc_nd}
\bar{C}= \left\{
\begin{array}{l}
1 \quad \text{at the lower boundary} \\
C_1/C_0 \quad \text{at the upper boundary}
\end{array}\right. \;.
\end{equation}

The bending energy of the membrane is defined by the integral of the contribution from the curvature to the energy density over the catenoid surface ($\Omega$), that is
\begin{equation}
W_B = \int \left(k C^2 + k_GK \right) d\omega \;.
\end{equation}
In dimensionless form, the total bending energy is written
\begin{equation}
\frac{W_B}{k C_0^2 L^2} = \int \left( \bar{C}^2 + \frac{k_G}{k}\frac{1}{C_0^2L^2}\bar{K} \right) d\bar{\omega} \;.
\end{equation}

Dividing by the dimensionless area of the catenoid $\bar{\Omega}=\Omega/L^2$, the dimensionless energy per area is $W_B/(k C_0^2 \Omega)$. We use the value $k_G/k=-0.9$ for the ratio of the Gaussian to bending modulus \cite{hu2012}.

To our knowledge, no analytical solution for a variable coefficient Helmholtz equation of the form of Eq.~\ref{eq:hape_mini_nd} is available. Therefore, we solve the system composed of Eqs.~\ref{eq:hape_mini_nd} and \ref{eq:bc_nd} with the finite element solver COMSOL Multiphysics\textsuperscript{\tiny\textregistered} 5.2a, and the `Surface reaction' module that has a built-in surface Laplacian. Parametric studies are conducted by exploiting the COMSOL model with the `COMSOL with Matlab' module.

\section*{Results}

\paragraph*{The Gaussian curvature of the catenoid governs the distribution of spontaneous curvature.}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat1}
\caption{Given a neck radius $r_n$, a catenoid-shaped neck connected to two identical reservoirs of curvature-inducing proteins shows a variation of spontaneous curvature along the arclength. (a) Schematic of a possible spontaneous curvature-inducing protein distributed along a catenoid connecting two vesicles. The two spherical parts are protein reservoirs imposing spontaneous curvature at the boundaries of the catenoid, and resulting in a distribution of curvature-inducing proteins along the neck.
(b) Geometry and boundary conditions of the catenoid. The arclength $s$ varies from $-L/2$ to $L/2$ and the boundary conditions are $C=C_0$. (c) Variation of dimensionless Gaussian curvature $K/L^2$ on a catenoid of neck radius $r_n=0.4L$. (d) Corresponding distribution of dimensionless spontaneous curvature. }
\label{fig:cat1}
\end{figure*}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat2}
\caption{Constraining the neck of a catenoid induces a switch in the sign of spontaneous curvature at constant total arclength and boundary conditions. (a) Axisymmetric geometry of six catenoids of various neck radii $r_n$ and same total arclength $L$. (b) Dimensionless Gaussian curvature along the arclength $s$ for various neck radii. (c) Resulting spontaneous curvature along the arclength for $C=C_0$ at both boundaries. (d) Corresponding distribution of spontaneous curvature on the catenoid. (e, f) Schematics of a distribution of curvature inducing proteins on a catenoid connecting two vesicles. (e) For a catenoid-shaped neck of radius larger than the critical radius $r_n>r_n^*$, only proteins inducing a spontaneous curvature of the same sign as $C_0$ are required to sustain the catenoid. (f) When the neck radius is below the critical neck radius $r_n<r_n^*$, proteins with spontaneous curvature of opposite sign as $C_0$ are necessary to sustain the catenoid-shaped neck.}
\label{fig:cat2}
\end{figure*}

We begin our analysis with the catenoid shown in Fig.~\ref{fig:cat1}(b) with a total arclength $L$ and neck radius $r_n=0.4L$. The geometry of a catenoid determines its Gaussian curvature along its arclength through Eq.~\ref{eq:K}. The Gaussian curvature of the catenoid considered here is displayed in Fig.~\ref{fig:cat1}(c). As expected $K$ is negative everywhere, with a maximum magnitude at the neck. How does the Gaussian curvature affect the distribution of protein-induced spontaneous curvature? We answer this question by solving the boundary value problem composed of Eq.~\ref{eq:hape_mini_nd} with $C=C_0$ at both boundaries (see Fig.~\ref{fig:cat1}(b)). The resulting field of spontaneous curvature is shown in Fig.~\ref{fig:cat1}(d). For this configuration, the spontaneous curvature is positive everywhere with a maximum at the neck, following the intensity of Gaussian curvature.

In order to interpret this spatially varying spontaneous curvature, one can think of the inclusion of a single type of conical protein into the lipid bilayer. In this case, a catenoid with fixed spontaneous curvature at the boundaries can be schematically represented as in Fig.~\ref{fig:cat1}(a), where two reservoirs of the curvature-inducing protein are connected to the boundaries. A variation of spontaneous curvature along the catenoid corresponds to a variation of protein surface density along the neck. The value of $C$ as a function of protein density depends on the protein and on the curvature inducing mechanism  \cite{lipowsky2013}.

\paragraph*{The energy required to maintain a catenoid-shaped membrane through spontaneous curvature presents a barrier at a critical neck radius.}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat3}
\caption{The switch of spontaneous curvature at the neck is accompanied by an energy barrier of the catenoid. (a) Normalized membrane spontaneous curvature at the neck as a function of the neck radius. (b) Energy per area of a catenoid as a function of the dimensionless neck radius. (Color symbols correspond to neck radii configurations shown in Fig.~\ref{fig:cat2}(a-c). Solid line is a visual guide.).}
\label{fig:cat3}
\end{figure*}

The radius of the neck is an important geometric parameter of catenoids, and is of particular interest to pre-fusion events in trafficking \cite{hurley2010, campelo2012, kukulski2012, messa2014}. We next investigate how the neck radius influences the distribution of spontaneous curvature along a catenoid.  We vary the neck radius between $r_n=0.1L$ and $r_n=0.6L$ as shown in Fig.~\ref{fig:cat2}(a). The resulting Gaussian curvatures along the arclength, presented in Fig.~\ref{fig:cat2}(b), show an increase of the curvature intensity at the neck as the neck decreases. Away from the neck however, a smaller neck radius produces a lower Gaussian curvature.

We solve the boundary problem for the spontaneous curvature, resulting in the distribution of $C$ depicted in Fig.~\ref{fig:cat2}(c). The boundary conditions are the same as the one shown in Fig.~\ref{fig:cat1}(b), with $C=C_0$ at both boundaries, corresponding to a neck connected to two equal reservoirs of curvature inducing proteins. Although the maximum of spontaneous curvature intensity is always at the neck, its value is a non-monotonic function of the neck radius and Gaussian curvature. For large neck radii, decreasing $r_n$ increases the maximum of C, until a critical neck radius $r_n^*$ below which $C$ at the neck switches signs. After this switch, further decreasing the neck radius lowers the intensity of spontaneous curvature. Fig.~\ref{fig:cat2}(d) shows the distribution of spontaneous curvature on the catenoids for the corresponding radii.

This non-intuitive switch-like behavior is surprising because neither the neck radius nor the resulting Gaussian curvature show a discontinuity. Furthermore, the boundary conditions for the spontaneous curvature are constant $C=C_0$. An intuitive understanding of this behavior can be obtained by considering a simplified case where the Gaussian curvature $K$ is constant along the arclength, reducing the shape equation for minimal surfaces to a one-dimensional simple harmonic oscillator. As shown in the Appendix, in this simplified case, reducing the neck radius is equivalent to decrease the period of the oscillator, which, when subject to fixed non-zero boundary conditions, leads to a series of diverging values for $r_n^*/L \sim \sqrt{2} / [\pi(1+2n)]$, with $n\in\mathbb{Z}$. For $n=0$ we obtain $r_n^*/L \simeq 0.45$, close to the value observed in Fig.~\ref{fig:cat3} for the catenoid. Interestingly, the value of neck radius at which the switch occurs does not depends on the value of the boundary condition, but only on the total arclength. Note that other critical values are expected for $n\neq 0$, and although these are observed for a constant $K$ (see Appendix), in the case of the catenoid, $K$ tends to zero away from the neck, suppressing the other possible switches.

The switch in sign of the spontaneous curvature as a function of neck radius can be interpreted as a requirement that another set of proteins with spontaneous curvature opposite to the one in the reservoir will be needed to minimize the energy of catenoids with smaller necks. This idea is shown in Figs.~\ref{fig:cat2}(e) and (f), where possible distributions of curvature-inducing proteins are depicted for necks larger and smaller than the critical radius.

To further identify the relationship between the switch in spontaneous curvature and the geometry, we plot in Fig.~\ref{fig:cat3}(a) the spontaneous curvature at the neck as a function of $r_n$. These results confirm the switch-like behavior described above and in the vicinity of a critical neck radius $r_n^*\simeq 0.33L$, the spontaneous curvature at the neck diverges, with positive values above $r_n^*$, and negative values below. In the two limits of large and small neck radii, the spontaneous curvature tends to $C_0$ everywhere. This is consistent with the two limit shapes of a catenoid: a tube and two inverted cones, both of which have a zero Gaussian curvature, and therefore no spatial variation of spontaneous curvature.

As show in Fig.~\ref{fig:cat3}(b), the bending energy required for the mechanical equilibrium of a catenoid-shaped neck through spontaneous curvature also shows an energy barrier at the critical neck radius $r_n^*$ corresponding to the switch in $C$. Away from this energy barrier, the radius of the neck can be reduced by small increases in the elastic energy of the system. The passage from one side to the other of the energy barrier will require additional mechanisms such as relaxation of the boundary conditions, external forces (e.g. actin pulling in clathrin mediated endocytosis \cite{boulant2011}), or a transient geometrical deviation from a symmetric catenoid. In the following, we investigate how the energy barrier in the catenoid-shaped neck can be modulated by spontaneous curvature and geometry.

\paragraph*{The differential in spontaneous curvature between the boundaries modulates the intensity of the energy barrier.}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat_DC1}
\caption{A spontaneous curvature differential between the two boundaries determines the width of the associated energy barrier but does not influence the position of the switch in spontaneous curvature. (a) Schematic of a catenoid with unequal boundary conditions. (b) Distribution of spontaneous curvature along the arclength for $C_1/C_0=10$ for various neck radii. (c) Distribution of spontaneous curvature along the arclength for $C_1/C_0=-5$. (d) Comparison of the energy per area of the catenoid for various boundary conditions. The larger the spontaneous curvature differential at the boundary, the larger the energy barrier corresponding to the sign switch. (e) Contour plot of the energy per area for $C_1/C_0$ varying between -15 and 15 as a function of the neck radius. The energy barrier (warm colors) is located around a constant critical neck radius of about $r_n^*=0.33L$.}
\label{fig:cat_DC1}
\end{figure*}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat_DC2}
\caption{For boundary conditions where the spontaneous curvature have opposite values ($C_1=-C_0$), the switch in the sign associated with the neck radius is nullified, and the spontaneous curvature at the neck is zero. (a) Spontaneous curvature along the arclength of a catenoid with $C_1=-C_0$ for various neck radii. (b) Energy per area of the catenoid as function of the neck radius; no energy barrier is observed for $C_1=-C_0$. (c) Schematic of a catenoid connecting two vesicles with curvature inducing proteins of opposite signs at the two spherical reservoirs. The smooth transition from $C_0$ to $-C_0$ requires a zero spontaneous curvature at the neck.}
\label{fig:cat_DC2}
\end{figure*}

How do the boundary conditions influence the distribution of spontaneous curvature in the neck? We consider the catenoid represented in Fig.~\ref{fig:cat_DC1}(a), where the spontaneous curvature at the upper boundary is $C_1\neq C_0$. This situation is likely to occur in a cellular context where the heterogeneous membrane composition may produce a differential in spontaneous curvature across the neck. We find that the switch-like behavior in spontaneous curvature persists independently of the ratio $C_1/C_0$. As shown in Figs.~\ref{fig:cat_DC1}(b) and (c), the distribution of $C$ is tilted to accommodate the boundary conditions, and the sign of the extremum is determined by the boundary condition with the largest absolute value. However the critical radius at which the switch occurs remain the same. This is better seen in Fig.~\ref{fig:cat_DC1}(d), where the critical radius associated with the energy barrier is independent of $C_1$. This observation is consistent with the expression for the critical neck obtained with the simple oscillator analogy that is independent of the boundary conditions (see Eq.~S2.6).

To fully explore the influence of the spontaneous curvature differential at the boundaries, we computed the energy of the catenoid for a wide range of $C_1/C_0$ as a function of $r_n$ (Fig.~\ref{fig:cat_DC1}(e)). The results confirm the behavior described above, except for $C_1=-C_0$ where a singularity seems to occur. The spontaneous curvature profile in this case, where the boundary of the catenoid have opposite curvatures, is shown in Fig.~\ref{fig:cat_DC2}(a). Here the switch in spontaneous curvature is suppressed, and $C=0$ at the neck independent of the neck radius. Correspondingly, the energy barrier vanishes as seen in Fig.~\ref{fig:cat_DC2}(b). Once again, this scenario can be interpreted as a neck connecting two reservoirs of proteins with the same magnitude of curvature but in opposite directions (see Fig.~\ref{fig:cat_DC2}(c)). The boundary conditions produce smooth transition from $C_1$ to $C_0$ along the catenoid, transiting by $C=0$ at the neck. This result is evident from the simple oscillator analogy, where the spontaneous curvature at the neck is proportional to $C_0+C_1$ (see Eq.~S2.4), and is therefore invariably zero for $C_1=-C_0$.

Interestingly, the energy per unit area away from the barrier suggests that for a large spontaneous differential at the boundaries, a small neck radius is energetically favorable compared to a large neck radius (Fig.~\ref{fig:cat_DC2}(b)). This result contrasts with the case $C_1=C_0$, where large neck radii are favorable (Fig.~\ref{fig:cat3}(b)).
The variation of spontaneous curvature differential across the neck may be a mechanism cells utilize to modulate the energy to form a neck. In particular, by accessing the large heterogeneity available due to membrane lipid composition and proteins, cells can disrupt the energy barrier associated with the transition from a large to a small neck radius, and \textit{vice versa}.

\paragraph*{The catenoid geometrical asymmetry modulates the location of the energy barrier.}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_cat_l0}
\caption{Asymmetry along the catenoid arclength determines the value of neck radius at which the spontaneous curvature sign switches. (a) Schematic of the geometry of the catenoid with a truncated arclength $L-l_0$. (b, c) Distribution of spontaneous curvature along the arclength for $l_0/L=$0.3 (b) and $l_0/L=$0.5 (c), for various neck radii. (d) Comparison of the energy per area of the catenoid for various degrees of asymmetry. The more truncated, the smaller value of the critical neck radius. For a half catenoid ($l_0/L=0.5$), the energy barrier and the sign switch disappear. (e) Contour plot of the energy per area for $l_0/L$ varying between 0.1 and 0.6 as a function of the neck radius. }
\label{fig:cat_l}
\end{figure*}

\begin{figure*}[t!bp]
\center
\includegraphics[width=\textwidth]{fig_3d_phase}
\caption{Bending energy per unit area of catenoids in the parameters space defined by dimensionless neck radius ($r_n/L$), spontaneous curvature asymmetry ($C_1/C_0$), and geometrical asymmetry ($l_0/L$). (a) Isosurfaces of the energy. The two dashed planes correspond to the energy landscapes shown in Fig.~\ref{fig:cat_DC1}(e) and \ref{fig:cat_l}(e). The dotted planes correspond to energy landscapes for $l_0/L=0.3$ shown in (b), and $C_1/C_0=-10$ shown in (c).}
\label{fig:3d_phase}
\end{figure*}

Thus far, we have only considered catenoids that are geometrically symmetric, that is, both sides of the neck have equal arc length. Yet, asymmetric catenoids are more common in the cellular environment. For instance, the neck connecting a tube to a larger membrane reservoir is a catenoid partially truncated \cite{derenyi2002, jiang2008}. We therefore ask how does geometric asymmetry influence the distribution of spontaneous curvature and energy associated witht the switch?

We conduct simulations on truncated catenoids of arc length $L-l_0$ as shown in Fig.~\ref{fig:cat_l}(a), with both boundaries subject to the same spontaneous curvature $C_0$. The profile of spontaneous curvature along the arclength are shown for different degrees of geometrical asymmetry in Figs.~\ref{fig:cat_l}(b) and (c). We find that reducing asymmetry in the catenoid modifies the critical neck radius at which the switch in spontaneous curvature occurs. As seen from Figs.~\ref{fig:cat_l}(d) and (e), where the energy of the catenoid is plotted as a function of the neck radius, the larger the degree of asymmetry $l_0$, the smaller the critical neck radius at which the energy barrier occurs.
Once half or more of the catenoid is cut off, corresponding to $l_0\geq L/2$, the energy barrier completely vanishes, allowing the neck radius to transition from large to small values through spontaneous curvature mechanisms only.

For completeness, we fully explore all the combinations of spontaneous curvature differential and geometric asymmetry of the catenoid by computing the corresponding energy space. As shown in Fig.~\ref{fig:3d_phase}(a), the results confirm the behaviors described above, where the differential in $C$ across the neck mainly influences the width and intensity of the energy barrier, while the geometrical asymmetry determines the critical neck radius corresponding to the energy barrier and the switch. This is further shown in the two energy isovalue planes presented in Figs.~\ref{fig:3d_phase}(b) and (c) which have overall similar behaviors as those plotted in Figs.~\ref{fig:cat_DC1}(e) and \ref{fig:cat_l}(e) respectively.

\section*{Discussion}

Necks are ubiquitous in membrane biology, appearing as a necessary step in vesiculation processes and connecting tubules to membranes reservoirs. These structures can be studied and understood as catenoids \cite{kozlovsky2003, mcdargh2016}, which are minimal surfaces with zero mean curvature and negative Gaussian curvature everywhere. The formation of necks has been associated with line tension \cite{liu2006}, the change in Gaussian modulus \cite{baumgart2005} and other forces, but the interaction between spontaneous curvature and Gaussian curvature had not been explored until now.

In this study, we explored the intricate relationship between Gaussian curvature, spontaneous curvature, and neck geometry. We asked, given a neck geometry connecting two reservoirs of curvature-inducing proteins, what spontaneous curvature field would satisfy the minimum energy requirement for a bilayer. We found a rather non-intuitive answer: the spontaneous curvature field depends on the Gaussian curvature and its intensity follows a switch-like behavior depending on the neck radius of the catenoid. The catenoid-shaped neck has an energy barrier at a critical neck radius corresponding to the switch in the sign of the  spontaneous curvature. We further identified two mechanisms allowing the modulation of this energy barrier -- (i) amplifying the spontaneous curvature differential at the boundaries increases the intensity and width of the energy barrier (Fig.~\ref{fig:cat_DC1}) and (ii) the geometrical asymmetry of the catenoid determines the critical neck radius at which the energy barrier is located (Fig.~\ref{fig:cat_l}). Moreover we found that the switching behavior is lost in specific cases: when the spontaneous curvature at the boundaries have opposite value (Fig.~\ref{fig:cat_DC2}), and when half or more of the catenoid is truncated (Fig.~\ref{fig:cat_l}).

Spontaneous curvature of lipid bilayers can be produced by a variety of relatively well understood mechanisms \cite{zimmerberg2006, jarsch2016, chabanon2017a}. In particular, the insertion of amphipathic $\alpha$-helix into lipid bilayers is known to induce curvature and is involved in several neck formation processes. The amphipathic $\alpha$-helixe is a conserved protein structure that can be found in Arf1 (involved in COP vesicle intracellular trafficking \cite{beck2011}), Epsin (involved in actin and clathrin mediated endocytosis \cite{boucrot2012}), and M2 proteins from influenza virus (involved in viral budding \cite{mishra2008, rossman2010, martyna2017}). All of these proteins have been shown to participate in membrane fission, which corresponds to the limiting shape of neck constriction \cite{beck2011, messa2014, martyna2017}. A similar mechanism is utilized by antimicrobial peptides (AMPs) to form buds and destabilize lipid membrane by inducing negative Gaussian curvature \cite{schmidt2010, schmidt2013, saikia2017}.
While, to our knowledge, no explicit relationship have been proposed between such curvature-inducing proteins and spontaneous curvature, the knowledge of how spontaneous curvature is distributed on a catenoid-shaped neck is a first step in mapping the protein distribution that produce a membrane neck. A theoretical example of simple relationship between membrane protein and spontaneous curvature is given in the Supplementary Material.

One of the main findings of this study is the existence of an energy barrier for catenoid-shaped necks at a certain neck radius. This energy barrier is accompanied with a switch in the sign of spontaneous curvature along the catenoid. This behavior can be related to several biological mechanisms relevant to neck formation and membrane fission. Several studies have shown that lipids with negative spontaneous curvature are important during the fission process \cite{kooijman2005, churchward2008, schmidt2011, schmidt2013}. We found that a change in the sign of the spontaneous curvature is important to overcome the energy barrier associated with reducing neck size. Therefore, it is possible that by harnessing the heterogeneity of lipid species \cite{vanmeer2008}, and chemical reactions that can lead to the formation of lipids with negative spontaneous curvature, pre-fission structures overcome the energy barrier associated with necks.

For instance, viral budding in influenza occurs in two main steps. First a neck is formed by a combination of scaffolding and lipid phase separation originating from the viral envelope. This step can only produce a neck of about 25 nm diameter, necessitating the action of another mechanism to further constrain the neck. During the second step, M2 amphipathic $\alpha$-helix insertion induces negative Gaussian curvature enabling the neck radius to reach values below 5 nm \cite{rossman2010, martyna2017}, at which point spontaneous membrane scission can occur \cite{campelo2012, liu2006}. It should be noted that no necking is possible with M2 amphipathic $\alpha$-helix only \cite{martyna2017}. The requirement for two distinct mechanisms in two regions of neck radii could be related to the energy barrier that we found as the neck radius of the catenoid decreases. Other evidence of switch-like behaviors are found in endocytosis where multiple studies have reported the existence of a snap-through instability \cite{walani2015, frolov2003, irajizad2017, hassinger2017}.  Furthermore, soap films, with no bending rigidity, also exhibit a structural instability when held as catenoids \cite{isenberg1978, powers2002}. Taken together, these findings suggest that perhaps, cellular membranes may utilize a fundamental geometric feature of catenoids to shape their membranes.

Our theoretical treatment results in two equations describing the equilibrium state of an elastic membrane conforming to a minimal surface: the shape equation (Eq.~\ref{eq:hape_mini}) that relates the membrane geometry (Gaussian curvature and surface Laplacian) to the spontaneous curvature, and the admissibility condition for the membrane tension (Eq.~\ref{eq:admiss_lambda}). These equations have been obtained by setting the mean curvature of the membrane to zero, which is a property of minimal surfaces.
\red{To further demonstrate the validity of our approach, we verified that the resulting geometry obtained by solving the general shape equation (without constraining the mean curvature) with the imposed field of spontaneous curvature from Fig.~\ref{fig:cat2}(c) are indeed catenoids. These results are presented in Section 3 of the Supplementary Material, and validate our approach.}

In the present model, we consider membrane deformations much larger than the bilayer thickness (see assumption 1), allowing us to treat the membrane as an infinitely thin surface. It is important however to note that for membrane structures barely larger than the membrane thickness, such as inverse cubic phases, the bilayer exhibits very large curvatures \cite{tran2015, demurtas2015}. In this case, phenomena such as thickness variation and tilt become important, and the mechanics of each individual monolayer must be taken into account \cite{siegel2004, wang2016, terzi2017}. It follows that the surface of interest with zero mean curvature is not the midplane of the bilayer anymore, but the neutral (or pivotal) plane, which is shifted from the midplane toward the water/lipid interface. Given that membrane necks studied here have characteristic sizes at least ten times larger than the bilayer thickness, we adopted the bilayer description where the midplane and neutral planes are identical. This assumption would not hold at stages close to membrane fission, requiring small scale modeling of the membrane. These issues have been discussed in detail in \cite{kozlovsky2002a, kozlovsky2003, kozlov2010}.

\red{
In general, the choice of the expression for the energetic contribution of the proteins to the membrane $A(\sigma)$ is a non-trivial endeavor. The energetic considerations for $A(\sigma)$ are discussed in \cite{steigmann2018} and specific examples provided in \cite{agrawal2011, callan-jones2016, belay2017}.  Models for entropic interactions of proteins with membranes have been explored in \cite{linden2012}, and the entropic contribution in multicomponent membranes have been studied in \cite{julicher1996, jiang2008, givli2012}. It is clear from these studies that more analyses between experiments and model equations are needed to identify the relevant constants and how $A(\sigma)$ may depend on the specific properties of the membrane proteins. In the case of minimal surfaces, the equations of motion decouple (Eqs.~\ref{eq:hape_mini} and \ref{eq:admiss_lambda}) allowing us to glean insight into $C(\sigma)$ without having to provide an explicit expression for $A(\sigma)$ and for $C(\sigma)$.
}

While our model assumes an idealized catenoid shape for membrane necks, it is possible that necks may not remain as exact catenoids and the dynamics of the neck formation process, including biochemical reactions, heterogeneity in membrane composition and moduli \cite{hassinger2017}, forces exerted by proteins and cytoskeleton molecules, and in-plane diffusion of lipids and proteins \cite{agrawal2011, rangamani2013a, rangamani2014, bahmani2015} play an important role during fission and fusion. Despite these shortcomings, we have identified some fundamental features of the interaction between Gaussian curvature and spontaneous curvature in catenoids. We summarize our findings as a phase space where the spontaneous curvature, neck radius, and the geometric asymmetry of the catenoid can be altered to obtain buds and necks of different radii (Fig. \ref{fig:buds}). These variables might serve as design parameters for artificial membrane constructs and a stepping stone for further investigation of how membrane geometry and proteins interact.

\begin{figure*}[tbp]
\center
\includegraphics[width=\textwidth]{fig_buds}
\caption{Three features control the distribution of a spontaneous curvature along a catenoid-shaped neck, the neck radius, the boundary conditions, and the asymmetry of the catenoid. These can be utilized to form or maintain buds connected to a reservoir of curvature inducing proteins through a catenoid.}
\label{fig:buds}
\end{figure*}

\begin{small}

redpajama_set_name: RedPajamaArXiv


text:
Anime Review: The Wind Rises (2013)
jcenno Anime June 1, 2022 May 30, 2022 2 Minutes
TL;DR – A fictional re-telling of real-life aeronautical engineer, Jiro Horikoshi.
Director Hayao Miyazaki's vast body of work explores many themes centred around humanity, and what he sees as the direction humanity is taking. A outspoken pacifist, Miyazaki often contrasts the beauty of creation against the horrors of violence in many of his films. He also has a distinct fascination for flight.
The ability to fly must be something Miyazaki sees as achieving freedom. Freedom from gravity, freedom from the weight of human failings, freedom from artistic restrictions, freedom from the boxes we are often forced into.
Whether it is a witch flying a broomstick (Kiki's Delivery Service), flying castles (Laputa: Castle in the Sky), pigs in seaplanes (Porco Rosso) or riding dragons (Spirited Away), it is clear that Miyazaki's passion for flight is not a mere motif in his films, but something that he sees as incredibly beautiful.
The Wind Rises is as literal as it gets to Miyazaki exploring the theme of flight. But this movie also expresses his immeasurably disdain towards violence and war. Set in the years leading up to World War II, the film tells the story of Jiro Horikoshi, a real-life aeronautical engineer, who designed and built fighter planes for Japanese Imperial Army.
Horikoshi was strongly opposed to the war, and it is clear that Miyazaki saw a kindred spirit. The Wind Rises is an unapologetic telling of how Horikoshi's love for flying was used by political powers and the military for war much to Horikoshi's heartbreak. He never sought to build planes to kill people, he built planes as an artistic expression of beauty, and The Wind Rises demonstrates that beauty in animated glory in a way only Studio Ghibli could deliver.
The dream sequences that Horikoshi has interacting with Italian aircraft designer, Giovanni Battista Caproni, are marvellous, and Miyzaki has not shied away from going into the technical challenges Horikoshi faced in building airplanes.
The Wind Rises also introduces the fictional love interest, Naoko Satomi, who Horikoshi eventually marries. However, she dies from tuberculosis, which somewhat mimics the overall tragedy Horikoshi experiences towards his planes being used for war.
The messages are much more blunt in The Wind Rises, which I imagine was intentional as this was meant to be Miyazaki's final film. However, I have since learned that Miyazaki has come out of retirement to direct How Do You Live?
As an artistic work, I can appreciate The Wind Rises but I confess that I found other Miyazaki films more poignant and enjoyable. For example, Porco Rosso which tells the tale of an Italian World War I fighter pilot cursed as a pig far more moving and dramatic.
Nevertheless, The Wind Rises is yet another film from Miyazaki's heart (and likely to him, the most important), and it is a heart that is filled with art and beauty and desire for peace. You cannot help but be moved by that as you experience The Wind Rises.
Published June 1, 2022 May 30, 2022
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Song Review: Stray Kids – Hello Stranger
Posted on July 16, 2020 by Nick	4 Comments
It's not unusual for an idol group to perform an OST track, but most of these songs are outsourced to producers who may or may not have a history with the group's discography. Very few OST songs could be considered highlights within an artist's catalog. More often, they're generic pop tracks or melodramatic ballads. In contrast, Stray Kids' Hello Stranger is composed by the guys themselves – or more specifically, their three-member production team 3RACHA. As such, it feels like a natural extension of their latest album.
If placed within Go Live's tracklist, Hello Stranger would be a highlight. It draws upon the rock influences that have often been part of their hip-hop sound, injecting jolts of guitar distortion to bolster its beat-heavy arrangement. There are also hints of brassy synth sprinkled throughout, which is a new touch for the group. Hello Stranger is more melodic than much of their recent work, but retains the punky energy that characterizes their style. Its chorus has a freewheeling appeal, driven by the guys' unrelenting personality. They've delivered stronger hooks in the past, but Hello Stranger showcases a nice blend of pop and shouty hype track.
There's a certain level of cacophony to Stranger's instrumental, as if the guys are constantly throwing ideas out there to see what sticks. This makes the track's taut arrangement even more important. A song like this could easily devolve into meaningless noise. But, it's well-structured and catchy, benefiting from the necessary palatability that OSTs demand. I don't think it will go down as a Stray Kids classic, but Hello Stranger is certainly a welcome mid-summer treat.
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4 thoughts on "Song Review: Stray Kids – Hello Stranger"
Imperial System says:
In a perferct world this was released instead of Gone Days. Then I wouldn't have to press skip every time I near the end of the album.
mymagoogle says:
So this song works because it is a tough guy song that doesn't take itself seriously. It also has the casual throwaway fun effect that comes from years of practice. You can't do this song as a rookie.
I think it is great.
Will it become an important part of the ouevre? They already have only a few years in a decent size back catalog of quality. But it could become a sentimental song they always sing anyway. For us OSK (outside south korean) fans, we tend to dismiss OST's faster than we should but OST form fully a third of the Gaon charts. There is a tendency to think, ah, blah, OST, whatev, but look at Gaho for example. (GAHO!) His biggest hit is now "Start" from Itaewon Class OST earlier this year. Even my few US Korean friends now know him by name where as before I was the one always going on about Gaho and they were yeah yeah. Like I am now. Gaho Gaho Gaho.
For the west, New Order "Shellshock" comes to mind as a soundtrack song that was small(ish) at the time but is now part of their greatest songs.
I really never knew I needed a song like this until I heard it. It always makes me laugh like wow a day or two ago this didn't exist and now I can't live without it. Amazing.
It is more melodic but still sounding SKZ. I like it a lot when it pops up while listening to SKZ's more hard hitting or experimental songs. It breaks up the flow for a bit before resuming classical SKZ songs.
Each week, I'll be taking a listen to the newest kpop releases and giving my thoughts. Check back frequently for new reviews and commentary on everything kpop!
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KTM X-Bow Comp R Featured in Road & Track
In Car News, Feature Articles, KTM X-BOW, T1 Club, X-Bow Cup USA
In the September issue of Road & Track magazine, fans and drivers of the KTM X Bow Comp R Limited Edition can find a nice write-up of the Young Schwarzenegger (a nickname given to the car by R&T editors) to gain some valuable insights about its performance, build, and thoughts from industry pros.
Overall, the KTM X-Bow Comp R has gained lots of popularity in the racing world, claiming its own profile last February in R&T by the same writer, Sam Smith.
In his initial breakdown, the KTM X-Bow Comp R boasts…
-300 hp @ 6400 rpm
-310 lb-ft @ 3200 rpm
-Six-speed manual transmission / Six-speed twin-clutch automatic
-Rear-wheel drive
-0–62 mph: 3.9 seconds (MFR testing)
-Top Speed: 144 mph (MFR testing)
-MSRP: $104,500 (Plus destination charge, which varies by dealer)
Fast-forward a season later, and Smith and other racing pros are still impressed with the high-performance machine:
"It's an impressive race car, and that's what it is; a race car. When I climb in, I close my brain's road-car file and open the one for open-wheelers. Get the tires up to temp, really work them. There's noticeable downforce."
If you're questioning whether or not the KTM X-Bow Comp R is right for you, Smith recommends the experience for "anyone who takes life seriously."
Check out the full article by clicking the download below or visit R&T to learn more! For information about our racing programs or to get involved in our Simraceway Series, feel free to contact us!
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Spotlight on Simraceway F3 Racer Alex Coigny
In Feature Articles, Major Events
Last weekend Alex Coigny, a frequent racer in our Simraceway F3 series and 5th place finisher in the F3 Winter Series Championship, headed back to his home country of Switzerland to begin his European racing schedule for 2016 in the VdeV European GT Sportscar Championship.
Alex in the Cockpit, obviously trying to remember the wise words of Tom Dyer
The VdeV is an endurance series that frequents the top racing tracks throughout Europe. The team will also be contesting several rounds of the International Endurance series for races of 12-24 hours in length. Alex will be driving for GPC Motorsport with fellow Swiss driver I'Alexander in a purpose built GT prototype car called a Vortex with a Corvette power plant that nearly matches the pace of the current top line GT3 cars in its debut race weekend! The first race was at Barcelona, which would be familiar to most race fans as the home of F1's pre-season test days just a few weeks ago.
Alex ran the first and last stints which included some slippery wet weather conditions. He was able to take the car to the checkered flag but unfortunately, due to some technical issues causing some extensive time spent on pit lane, a good result was not forthcoming. The team is determined to get these issues sorted before the next race at Le Mans Bugatti course in April as the potential of the car was already apparent. Also, watch out for another familiar face in the car later on in the year as Simraceway's very own Tom Dyer will be teaming up with Alex and the GPC team in the 24 hour race at Paul Ricard in July. We certainly wish Alex the very best of luck and look forward to seeing him back in the F3 cockpit here at Sonoma at the 1st race of the F3 Summer Series in May.
Exclusive interview with Pietro Fittipaldi
In Company News, Feature Articles
Pietro Fittipaldi is one of the brightest talents in formula car racing, and is about to embark on the 3.5 V8 series (formerly Renault 3.5). He is the grandson of the great Emerson Fittipaldi, and nephew of Christian & Max Papis.
The following is a short interview after we spent the day with him at the Simraceway Performance Driving Center in preparation of his return to Europe. He helped us with some benchmark times for the current crop of young drivers who will be coming through the driver development program this year.
He is a very smart and mature driver for his age, and also very very fast, he ended up breaking the F3 lap record at Sonoma Raceway by over a second! Make sure you follow his season, he is sure to make an impression in his rookie year. Enjoy.
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Photographer: Jay Watson
Simraceway Performance Driving Center Hosts Autoweek Magazine
In its second year now, the Simraceway Performance Driving Center was proud to host the Autoweek Fantasy Camp where 20 individuals got to live the pampered life of an automotive journalist. 10 cars were invited to the party: the Lexus IS-F, BMW M3, Dodge Charger Hellcat, Cadillac ATS, Chevrolet SS, Audi S4, Mercedes Benz C400, Chrysler 300C & Acura TLX. Ganassi Racing's dynamic duo Scott Pruett & Joey Hand were also there to offer some fun racing stories as well as some wild rides in the Lexus RC-F.
Starting with a street drive through the winding hills and valleys of Sonoma/Napa, the "editors for a day" rotated through the cars to get a good feel for each car. They ended up at Simraceway Performance Driving Center at Sonoma Raceway to start the serious business of really putting these cars to the test. Here our instructors went along for the ride, helping with track and driving tips as they drove the cars on our performance Autocross as well as the raceway itself, all the while writing their thoughts on how each one stacked up against each other. Some serious rubber was burned, especially in the Dodge Charger Hellcat as horsepower doesn't suck, where no one could resist holding that throttle all the way to the floor (and the noise wasn't half bad either)! This was a unique opportunity that everyone seemed to have a ball being a part of. Even our instructors seemed to find some new cars they'd like to add to their garage. After a fantastic day of endless car talk and fuel burning fun, they headed over to Aston Martin headquarters at our friends TRG's raceshop & winery. We are already looking forward to next year's program, so stay tuned to Autoweek to see if you can be one of the lucky ones in 2016!
—Paul Charsley
Pictures from the day:
How to Get Around COTA…Fast!
In Feature Articles, Game News
Simraceway Performance Driving Center instructor Matt Bell is one of a select group: a driver who has taken on Circuit of The Americas twice. In fact, in March of this year the Californian got up-close-and-personal with the Austin circuit twice in one day—once in a Chevrolet Camaro SS GS.R, and once in an Audi R8 LMS.
So who better than the expert GT racer, who has placed second in the Continental Tire Sports Car Challenge Series Driver's Championship (GS Class) two years in a row, to guide us through a lap of COTA in our R8 LMS ultra–as Simraceway players battle to record the quickest times with that same car/track combo and qualify for the 50th Sunday Race-Off?
Read on to benefit from his video and guide, which is also available to download as a PDF.
Simraceway Pro Driver Dario Franchitti Retires from Racing
In Feature Articles, Racing News
Four-time IndyCar champion and triple winner of the Indianapolis 500, Dario Franchitti announced yesterday that he would be retiring from professional motorsport due to medical concerns resulting from his crash in Houston. As someone we've worked with closely over the last few years, that news provokes a range of emotions.
As racing fans, we share in the sadness that will be felt across the entire sport–we took immense pleasure from his continued successes and even had the privilege of sharing in some of his biggest victories.
[embed width="620″ height="349″]http://www.youtube.com/watch?v=55_MWwxM3EU[/embed]
However, having also been lucky enough to get to know the man behind the legend, we're thankful that Dario is taking a route that will keep him out of harm's way in the future.
Circuit of The Americas Comes Full Circle
In Feature Articles, Monthly Themes, Racing News
Simraceway and Circuit of The Americas have always enjoyed a close relationship–we even managed to launch our version of the course three weeks before its real gates swung open–so, on the eve of its second US GP, we're naturally delighted that the first purpose-built Grand Prix facility in the U.S. has been such a hit in its first year.
Read on to find out more about COTA's successful first twelve months–in both the virtual and real worlds!
Real vs. Virtual Ep. 4: Audi R8 LMS ultra
In Car News, Feature Articles, Game News
With the new Audi R8 LMS ultra already proving a popular addition to the Simraceway showroom, we're taking a closer look at just how much effort and expertise goes into the creation of our cars in the latest episode of our Real vs. Virtual series, recently launched on our YouTube channel. Read on to find out more.
"I've already learned a couple of things before we even take the real car out on the track. I know exactly what gear I should be in, what kind of entry speed I should have, where my break markers should be", reflected a visibly-impressed James Sofronas.
The GMG Racing owner, co-founder, and driver was talking to our Head of Physics, Nico Rondet, at the Simraceway Performance Driving Center as the pair, aided by the hard-working Simraceway physics team, tuned our virtual R8 LMS ultra to behave exactly like the car Sofronas' team had driven into battle in 2012.
Check out the video below to see how they got on.
Palatov Motorsport's Fire-Breathing D4PPS Wins at Pikes Peak
In Car News, Feature Articles, Racing News
According to Wikipedia, "Pikes Peak International Hill Climb…is an annual automobile and motorcycle hill climb to the summit of Pikes Peak in Colorado" on a track that "measures 12.42 miles (19.99 km) over 156 turns, climbing 4,720 ft (1,440 m) from the start at Mile 7 on Pikes Peak Highway, to the finish at 14,110 ft (4,300 m), on grades averaging 7%."
While completely accurate, what that selection of stats fails to convey is just how spine-chillingly fearsome this popular event is. Filled with hardcore, take-no-prisoners corners that are often taken at insane speeds, its drivers are seemingly unperturbed by its blood-curdling collection of blind exits and run-off areas that would be more accurately described as "fall-off areas".
When Ernest Hemingway observed there were "but three true sports – bullfighting, mountain climbing, and motor-racing", it's doubtful he was aware there was actually an event fusing two of those endeavors into one challenging contest. And it's the enormity of this challenge that brings so many contestants to the mountains of Colorado each year. This year, our good friends at Palatov Motorsport decided to take up the challenge–and this is our account of how they got on.
Team Cal Simraceway Gear Up for Their Biggest Challenge Yet
In Car News, Feature Articles
Simraceway has partnered with the Formula SAE team at UC Berkley to assist its budding engineers and drivers as they develop and race their B12 car in the 2012-2013 season. In a previous post we covered the early stages of their preparation, including the all-important driver selection, and we now join Team Principal Shin Scott and his FSAE team as they continue to ready the car and drivers for the grand final in Nebraska.
Simraceway–Helping Shape the Future of Motorsport
After an encouraging 2011-12 season, Simraceway has once again teamed up with the Formula SAE team at UC Berkeley to help them with their 2012-13 entry in the prestigious contest designed to unearth the engineers of the future. We'll be playing an active role in helping the team develop their new car as well as supplying the tools and knowledge to enable them to find and train their drivers.
To experience first-hand the product of last year's partnership, you can purchase the FSAE B11 (nicknamed "Vader") here for mere pocket change. To find out how this season's preparations are going, carry on reading as we highlight the team's journey right up to the final in Nebraska.
Simraceway Event Winners Take to the Track
In Feature Articles
A bright and sunny California day saw the Evo X Mid-Ohio Event winners, Peter Duivelaar (pro_drifter100) and Steven Diem (acerockolla), join us at the Simraceway Performance Driving Center. They were greeted by Jeff Westphal, one of its instructors, and Nico Rondet, its Chief Instructor, who would be coaching them over the next two days as they got to grips with the Evo X and the Infineon Raceway circuit. After a quick intro, it was time to see if they are as quick in the real world as they are in the virtual one!
Simraceway and Palatov Motorsport Shakedown the D4
A bright and sunny morning sees Dennis Palatov and his Palatov Motorsport team join us at Infineon Raceway, home of the Simraceway Performance Driving Center, for a shakedown session of his exciting new D4 track/race car. With motoring journalists Leo Parente and Brian Makse also in attendance, we're keen to see how the Simraceway D4 compares to the real-life track weapon, so we can give you the most realistic racing experience possible.
An Unconventional 'Road to Indy'
"I'm never going to give up. Racing is my life."
These are words that I have heard from many kids (even from 'kids' in their twenties) at the local kart track, but I recently had the chance to speak to a young man who really means them–and continues to prove it every day by chasing his dream, despite the difficult hand he was dealt at a young age.
Simon Says—A Lap Around Mid-Ohio with the Track Record Holder
"I have the all-time track record at Mid-Ohio—I think it was a 1:03:7." It was at this point of my conversation with IndyCar, sportscar, Aussie V8 and rally driver extraordinaire, Simon Pagenaud, that I fell off my chair.
The 27-year-old Indianapolis-based Frenchman loves to go fast and in the last 12 months he has taken every available opportunity to prove it. Pagenaud has driven for the factory Peugeot squad in the Intercontinental Le Mans Cup, he's been 'super sub' in the IndyCar Series, he's been a factory Honda driver in the Continental Tire Series for touring cars and he's even found time to rally a Citroen C2!
That blistering lap time at the Mid-Ohio Sports Car Course was set in a 2007 Champ Car (above) described simply by Pagenaud as "fantastic" with a "combination of power and grip that made that track layout really fun."
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Daceton boltoni is a Neotropical species of arboreal ants in the subfamily Myrmicinae. The species occurs in Peru and Brazil and is similar to its sister species, D. armigerum.

Distribution
It seems to be exclusively canopy-dwelling and is known to occur in Iquitos, Peru, and Manaus and Cotriguaçu, Brazil. D. boltoni is sympatric with D. armigerum. Although its known distribution is currently only two locations in the Amazonian forest, it is possible and indeed likely that D. boltoni shares a broadly overlapping distribution with D. armigerum.

Description
The worker caste of D. boltoni shares many important character states with that of its sister species D. armigerum, including the heart-shaped head, the large eyes located on a low cuticular prominence, the number of apical mandibular teeth, and general habitus. Daceton boltoni differs from D. armigerum by the absence of a specialized row of thick setae on the inner (masticatory) margin of the mandibles; by mandibles that are slightly shorter and more stout, which could indicate differences in prey preferences between the two species; by a broad gap, when seen in profile, between the bases of the fully closed mandibles and the margins of the head capsule; by shallow depressions adjacent to and ventral to the mandibular insertions; by long and simple lateral pronotal spines; by a weakly impressed metanotal groove; and by subdecumbent to decumbent hairs on the tergite of abdominal segment IV.

Behaviorally, D. boltoni appears to be very similar to D. armigerum. However, drop tests conducted at the type locality indicate that D. boltoni individuals exhibit weak and inconsistent aerial gliding behavior relative to those of D. armigerum.

Gynes and males are unknown.

Worker variation
Among the specimens studied in the original description, Azorsa & Sosa-Calvo (2008) documented some morphological variation, including:
 All castes with sides of head lacking a broad gap between bases of mandibles and margins of head capsule when mandibles are fully closed, with the exception of the two minor workers studied, in which case there is a narrow gap.
 Erect hairs on the ocular crest are present in all workers examined. However, the number of hairs varies among specimens. We suspect that these hairs are fragile and can be easily lost, which may account for the variation observed between specimens. This seems also to apply to the standing hairs on the median promesonotum and behind the posterior tubercles of the promesonotum.
 Humeral tubercles are strongly reduced, sometimes forming a carina or absent, especially in smaller workers.
 The propodeal spines of all of the Peruvian specimens examined converging at the tips (U-shaped, when seen in fronto-dorsal view), whereas in most of the specimens from Brazil the propodeal spines are diverging, more like the state in D. armigerum.
 Petiolar spines short, almost absent in the smaller castes. The petiolar spines are more developed in the specimens from Brazil.

References

Myrmicinae
Insects described in 2008
Hymenoptera of South America
Hymenoptera of Brazil
Invertebrates of Peru

redpajama_set_name: RedPajamaWikipedia