Theory of the asymmetric ripple phase in achiral lipid membranes

We present a phenomenological theory of phase transitions in achiral lipid membranes in terms of two coupled order parameters -- a scalar order parameter describing lipid chain melting, and a vector order parameter describing the tilt of the hydrocarbon chains below the chain-melting transition. Existing theoretical models fail to account for all the observed features of the phase diagram, in particular the detailed microstructure of the asymmetric ripple phase lying between the fluid and the tilted gel phase. In contrast, our two-component theory reproduces all the salient structural features of the ripple phase, providing a unified description of the phase diagram and microstructure

Phase behavior of two-component lipid membranes: theory and experiments

The structure of the ripple phase of phospholipid membranes remains poorly understood in spite of a large number of theoretical studies, with many experimentally established structural features of this phase unaccounted for. In this article we present a phenomenological theory of phase transitions in single- and two-component achiral lipid membranes in terms of two coupled order parameters -- a scalar order parameter describing {\it lipid chain melting}, and a vector order parameter describing the {\it tilt of the hydrocarbon chains} below the chain-melting transition. This model reproduces all the salient structural features of the ripple phase, providing a unified description of the phase diagram and microstructure. In addition, it predicts a variant of this phase which does not seem to have been experimentally observed. Using this model we have calculated generic phase diagrams of two-component membranes. We have also determined the phase diagram of a two-component lipid membrane from x-ray diffraction studies on aligned multilayers. This phase diagram is found to be in good agreement with that calculated from the model.Comment: 10 pages, 10 figure

Test results for composite specimens and elements containing joints and cutouts

A program was conducted to develop the technology for joints and cutouts in a composite fuselage that meets all design requirements of a large transport aircraft for the 1990s. An advanced trijet derivative of the DC-10 was selected as the baseline aircraft. Design and analysis of a 30-foot-long composite fuselage barrel provided a realistic basis for the test effort. The primary composite material was Hexcel F584 resin on 12 K IM6 fiber, in tape and broadgoods form. Fiberglass broadgoods were used in E-glass and S-glass fiber form in the cutout region of some panels. Additionally, injection-molded chopped graphite fiber/PEEK was used for longeron-to-frame shear clips. The test effort included four groups of test specimens, beginning with coupon specimens of mono-layer and cross-piled laminates, progressing through increasingly larger and more complex specimens, and ending with two 4- by 5-foot curved fuselage side panels. One of the side panels incorporated a transverse skin splice, while the second included two cabin window cutouts

Maximal fluctuations of confined actomyosin gels: dynamics of the cell nucleus

We investigate the effect of stress fluctuations on the stochastic dynamics of an inclusion embedded in a viscous gel. We show that, in non-equilibrium systems, stress fluctuations give rise to an effective attraction towards the boundaries of the confining domain, which is reminiscent of an active Casimir effect. We apply this generic result to the dynamics of deformations of the cell nucleus and we demonstrate the appearance of a fluctuation maximum at a critical level of activity, in agreement with recent experiments [E. Makhija, D. S. Jokhun, and G. V. Shivashankar, Proc. Natl. Acad. Sci. U.S.A. 113, E32 (2016)].Comment: 12 pages, 5 figure

Dynamics of broken symmetry nodal and anti-nodal excitations in Bi_{2} Sr_{2} CaCu_{2} O_{8+\delta} probed by polarized femtosecond spectroscopy

The dynamics of excitations with different symmetry is investigated in the superconducting (SC) and normal state of the high-temperature superconductor Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8+\delta}$ (Bi2212) using optical pump-probe (Pp) experiments with different light polarizations at different doping levels. The observation of distinct selection rules for SC excitations, present in A$_{{\rm 1g}}$ and B$_{{\rm 1g}}$ symmetries, and for the PG excitations, present in A$_{{\rm 1g}}$ and B$_{{\rm 2g}}$ symmetries, by the probe and absence of any dependence on the pump beam polarization leads to the unequivocal conclusion of the existence of a spontaneous spatial symmetry breaking in the pseudogap (PG) state

Soft inclusion in a confined fluctuating active gel

We study stochastic dynamics of a point and extended inclusion within a one dimensional confined active viscoelastic gel. We show that the dynamics of a point inclusion can be described by a Langevin equation with a confining potential and multiplicative noise. Using a systematic adiabatic elimination over the fast variables, we arrive at an overdamped equation with a proper definition of the multiplicative noise. To highlight various features and to appeal to different biological contexts, we treat the inclusion in turn as a rigid extended element, an elastic element and a viscoelastic (Kelvin-Voigt) element. The dynamics for the shape and position of the extended inclusion can be described by coupled Langevin equations. Deriving exact expressions for the corresponding steady state probability distributions, we find that the active noise induces an attraction to the edges of the confining domain. In the presence of a competing centering force, we find that the shape of the probability distribution exhibits a sharp transition upon varying the amplitude of the active noise. Our results could help understanding the positioning and deformability of biological inclusions, eg. organelles in cells, or nucleus and cells within tissues.Comment: 16 pages, 9 figure

THE DYNAMICS OF RAPE IN MODERN INDIAN SOCIETY

Rape is malum in se. In modern India the institution of rape has flourishedimmensely in recent times, and presently it is a national problem. It is a challenge to thecontemporary thinking. Gender equality is enshrined in the Indian constitution. In ancienttimes rape existed in Europe while women in India had divine personification as Shakti andin modern times millions of Indians visit Shakti temples with liberal offerings.This paper addresses dynamics of rape with particular reference to India. Rape is amultidimensional and dynamic phenomenon. Its perception may vary from radical to liberal,and the legal definition keeps evolving. Mathematically it may be modeled as a space-timefunction. In 2013 the definition of rape was revised both in India and US. It, however,differs. The paper examines recently introduced Indian law to reduce rape incidents.There are various areas which need attention to have insight into the phenomenon ofrape and measures to control the incidents. This includes understanding the effect of socioeconomic-demographic predictor variables in reduction of the incidents. The authors haveapplied statistical analysis using correlation to rape data from all the 35 regions of Indiawith eleven socio-economic-demographic predictor variables to find the effect of thevariables on incidents of rape. It was found that only literacy status, or literacy status as aproxy, for male and female in urban population indicated significant desirable effect on thenumber of rape incidents. This sets a direction for further research. The rape challenge shouldbe addressed with afresh look from multidisciplinary perspective besides law andenforcement. The fusion of data, analyses, and ideas including from sociological, cultural,psychological, and religious aspects, and encouraging merging of tools from disciplines,should provide an insightful and sound approach to find solution to the intractable socialproblem. Also social change with the universal wisdom thoughts of great minds like MahatmaGandhi and Elie Wiesel is desirable to eliminate ills, including rape, from the modern society

Effect of elevated CO2 and high temperature on seed-set and grain quality of rice

Hybrid vigour may help overcome the negative effects of climate change in rice. A popular rice hybrid (IR75217H), a heat-tolerant check (N22), and a mega-variety (IR64) were tested for tolerance of seed-set and grain quality to high-temperature stress at anthesis at ambient and elevated [CO2]. Under an ambient air temperature of 29 °C (tissue temperature 28.3 °C), elevated [CO2] increased vegetative and reproductive growth, including seed yield in all three genotypes. Seed-set was reduced by high temperature in all three genotypes, with the hybrid and IR64 equally affected and twice as sensitive as the tolerant cultivar N22. No interaction occurred between temperature and [CO2] for seed-set. The hybrid had significantly more anthesed spikelets at all temperatures than IR64 and at 29 °C this resulted in a large yield advantage. At 35 °C (tissue temperature 32.9 °C) the hybrid had a higher seed yield than IR64 due to the higher spikelet number, but at 38 °C (tissue temperature 34–35 °C) there was no yield advantage. Grain gel consistency in the hybrid and IR64 was reduced by high temperatures only at elevated [CO2], while the percentage of broken grains increased from 10% at 29 °C to 35% at 38 °C in the hybrid. It is concluded that seed-set of hybrids is susceptible to short episodes of high temperature during anthesis, but that at intermediate tissue temperatures of 32.9 °C higher spikelet number (yield potential) of the hybrid can compensate to some extent. If the heat tolerance from N22 or other tolerant donors could be transferred into hybrids, yield could be maintained under the higher temperatures predicted with climate change

Strategy Sort of Died Around April of Last Year for a lot of Us

The role of the Chief Information Officer (CIO) is one of facilitating executive decisions regarding the innovation, provision and use of state-of-the-art Information and Communication Technologies (ICT). The aim of this paper is to investigate CIO perceptions of strategy and ICT investment through qualitative interviews with CIOs from leading UK financial sector organisations. We were keen to find out how these executives strategise while coping with the increasing ubiquity and complexity of ICT on one hand and hyper business pressures on the other. As the title suggests, we found that recent changes in the market conditions, as well as in the trust bestowed technology as an agent for radical change, have had serious consequences for the perceptions of risk, strategy and ICT investment. CIOs expressed the dot-com boom to bust transition in terms of a shift from a higher-risk, top-down technology led strategy centred on killer applications towards a lower-risk, bottom-up, organic approach to strategy with the purpose of providing open, user driven enabling infrastructures for competitive advantage. We also note the implications of these trends for the value assessment activity and the enhanced value skill base which information age professionals would increasingly need