Role of cytoskeletal remodeling in T cell receptor signaling and integrin activation at the immunological synapse

The efficiency of an immune response critically depends on the ability of T cells to respond to antigens. Upon encountering cognate antigenic peptides on the surface of antigen-presenting cells, T cells form a specialized interface, termed the immunological synapse (IS), which serves as the site of information transfer between the cells. This contact zone is characterized by the enrichment of signaling receptors, kinases and adaptor proteins, and is the site of extensive cytoskeletal remodeling. The versatile nature and spatio-temporal regulation of signaling cascades at the IS has long been recognized but the exact mechanisms that coordinate these processes remain poorly understood. In this work we have investigated the role of cytoskeletal remodeling in propagation of signaling events that lead to T cell activation. Using human T cell lines and primary T cells, we demonstrate that F-actin flow is largely driven by actin polymerization, rather than by myosin IIA contraction. While myosin IIA is able to exert forces on the cytoskeleton, it is dispensable for bulk network flow. Conversely, myosin IIA controls the extent of cell spreading and synaptic symmetry. We have also found that ongoing retrograde flow of F-actin sustains calcium mobilization at the level of release from endoplasmic reticulum stores. This defect is likely due to loss of PLCgamma1 activity at the IS, since the concentration of phosphorylated PLCgamma1 plummets upon F-actin immobilization. Furthermore, we have examined whether F-actin remodeling is required for integrin LFA-1 activation, which in turn strengthens conjugate formation and costimulation. Taking advantage of stimulatory planar lipid bilayers and cell-cell conjugates, we show that F-actin flow drives affinity maturation and spatial organization of LFA-1 at the IS. These observations are in line with a mechanotransduction model, in which F-actin-derived force induces integrin conformational change, thereby modulating binding affinity for ligand. The net inward movement of F-actin also recruits LFA-1 to the interface, thereby increasing its effective concentration. Taken together, these findings indicate that ongoing remodeling of actin cytoskeleton is required to sustain signaling and to choreograph spatio-temporal organization of receptors and their associated complexes at the IS during early phases of T cell activation

РОЗРОБКА РЕЦЕПТУРИ ЖИРОВОЇ НАЧИНКИ ДЛЯ НОВОГО ВИДУ ВАФЕЛЬНИХ ВИРОБІВ

The article gives an opportunity to develop the technology of fatty filling for waffles and low-calorie wafers by replacing sugar with a mixture of sweet extracts from the leaves of stevia with erythritol. The expediency of regulating the amount of dry matter due to the introduction of dry skim milk whey has been proved. The whey is a raw material component that further enriches the finished product on minerals and vitamins that are healthy for the human body. The possibility of additional introduction of of beta-carotene, as a dye and ascorbic acid, as a stabilizer of fatty wafer fillings has been investigated. In order to improve the quality and safety of finished products, the possibility of using in the technology of fatty fillings for wafer products a new type of confectionery fat of domestic production "Fettifil" has been experimentally confirmed.В статье приведена возможность разработки технологии жировой начинки для вафель и вафельных изделий пониженной калорийности за счет замены сахара на смесь экстракта сладкого из листьев стевии с еритротолом. Доказана целесообразность регуляции количества сухих веществ за счет внесения обезжиренной молочной сыворотки, как сырьевого компонента, которая дополнительно обогатит готовый продукт полезными для организма человека минералами и витаминами. Исследована возможность дополнительного внесения бета-каротина, в качестве красителя и аскорбиновой кислоты, в качестве стабилизатора жировых вафельных начинок. Экспериментально подтверждена возможность использования нового вида кондитерского жира отечественного производства "Феттифил" в технологии жировых начинок для вафельных изделий с целью повышения качества и безопасности готовой продукции.У статті наведено можливість розробки технології жирової начинки для вафель та вафельних виробів зниженої калорійності за рахунок заміни цукру на суміш екстракту солодкого з листя стевії з еритротолом. Доведена доцільність регуляції кількості сухих речовин за рахунок внесення сухої молочної знежиреної сироватки, як сировинного компонента, що додатково збагатить готовий продукт на корисні для організму людини мінерали та вітаміни. Досліджена можливість додаткового внесення бета-каротину, в якості барвника та аскорбінової кислоти, в якості стабілізатора жирових вафельних начинок. Експериментально підтверджена можливість використання  нового виду кондитерського жиру вітчизняного виробництва "Феттіфіл" у технології жирових начинок для вафельних виробів з метою підвищення якості та безпеки готової продукції

Адсорбция водорода на чистых и допированных углеродных нанотрубках: DFT моделирование

Рассматривается адсорбция нескольких молекул водорода на внешней и внутренней поверхности комплекса "углеродная нанотрубка (9,9)@Li". Численные эксперименты проводились в пакете SIESTA в двух приближениях для обменно-корреляционного потенциала: приближении обобщенных градиентов (GGA) и приближении локальной электронной плотности (LDA). Моделирование показало, что добавление атома лития позволяет увеличить энергию адсорбции 3-4 молекул водорода (расположенных в первой координационной сфере Li) по сравнению со случаем сорбции на чистой поверхности углеродной нанотрубки. При этом энергии связи попадают в диапазон 200-700 мэВ/(молекулу Н[2]), обеспечивающий эффективность циклов сорбции/десорбции газа, только в случае внутренней сорбции

Анализ программного обеспечения для трехмерного моделирования и оптимизации разработки месторождений нефти и газа

Анализируются наиболее распространенные на рынке программного обеспечения средства и комплексы, применяемые в России и за рубежом для интерпретации результатов исследований и создания цифровых 3D-моделей месторождений нефти и газа. Представлены технологические линейки программных модулей, обеспечивающие выполнение всего комплекса работ по моделированию разработки месторождений. Предложены авторские инструментальные средства (алгоритмические и программные) для оптимизации процесса моделирования разработки месторождений нефти и газа. Результаты анализа позволяют аргументировать выбор рационального набора инструментальных средств из арсенала российского и зарубежного программного обеспечения

A spatial contrast retina with on-chip calibration for neuromorphic spike-based AER vision systems

We present a 32 32 pixels contrast retina microchip that provides its output as an address event representation (AER) stream. Spatial contrast is computed as the ratio between pixel photocurrent and a local average between neighboring pixels obtained with a diffuser network. This current-based computation produces an important amount of mismatch between neighboring pixels, because the currents can be as low as a few pico-amperes. Consequently, a compact calibration circuitry has been included to trimm each pixel. Measurements show a reduction in mismatch standard deviation from 57% to 6.6% (indoor light). The paper describes the design of the pixel with its spatial contrast computation and calibration sections. About one third of pixel area is used for a 5-bit calibration circuit. Area of pixel is 58 m 56 m, while its current consumption is about 20 nA at 1-kHz event rate. Extensive experimental results are provided for a prototype fabricated in a standard 0.35- m CMOS process.This work was supported by Spanish Research Grants TIC2003-08164-C03-01 (SAMANTA), TEC2006-11730-C03-01 (SAMANTA-II), and EU grant IST-2001-34124 (CAVIAR). JCS was supported by the I3P program of the Spanish Research Council. RSG was supported by a national grant from the Spanish Ministry of Education and Science.Peer reviewe

Testing the Randall-Sundrum Model at a High Energy e−e−e^- e^- Collider

We study the process $e^- e^- \to e^- e^-$ at a high energy $e^- e^-$ collider including the effect of graviton exchanges in the warped gravity model of Randall and Sundrum. Discovery limits for gravitons are established and the effects of polarization are discussed.Comment: 10 pages LaTeX, 6 postscript figure

Influence of torrefaction on the grindability and reactivity of woody biomass

7 pages, 5 figures, 4 tables.-- Available online Oct 23, 2007.The use of biomass to produce energy is becoming more and more frequent as it helps to achieve a sustainable environmental scenario. However the exploitation of this fuel source does have drawbacks that need to be solved. In this work, the torrefaction of woody biomass (eucalyptus) was studied in order to improve its properties for pulverised systems. The process consisted in a heating treatment at moderate temperature (240, 260, 280°C) under an inert atmosphere. The grindability of raw biomass and the treated samples was compared and an improvement in the grindability characteristics was observed after the torrefaction process. Thermogravimetric analysis of the samples was carried out in order to study their reactivity in air. The DTG curves of the torrefied biomass showed a double peak nature. The kinetic parameters were calculated for each reaction stage. The torrefaction process was found to influence the parameters of the first stage, whereas those corresponding to the second remained unaffected.This work was carried out with financial support from the Spanish CDTI (Project CENIT PiIBE) and ELCOGAS, S.A. M.G.P. and C.P. acknowledge the support from the CSIC I3P Program co-financed by the European Social Fund, and J.F. from the Plan Regional de Investigacion del Principado de Asturias.Peer reviewe

Thermal non-Gaussianity in holographic cosmology

Recently it has been shown that the thermal holographic fluctuations can give rise to an almost scale invariant spectrum of metric perturbations since in this scenario the energy is proportional to the area of the boundary rather than the volume. Here we calculate the non-Gaussianity of the spectrum of cosmological fluctuations in holographic phase, which can imprint on the radiation dominated universe by an abrupt transition. We find that if the matter is phantom-like, the non-Gaussianity $f_{NL}^{equil}$ can reach ${\cal O}(1)$ or even be larger than ${\cal O}(1)$. Especially in the limit $\omega\to -5/3$, the non-Gaussianity is very large and negative. Furthermore, since the energy is proportional to the area, the thermal holographic non-Gaussianity depends linearly on $k$ if we neglect the variation in $T$ during the transition (fixed temperature).Comment: 13 pages, Minor corrections and one reference added;v3,minor correction

Thermal fluctuations in viscous cosmology

In this paper we investigate the power spectrum of thermal fluctuations in very early stage of viscous cosmology. When the state parameter as well as the viscous coefficient of a barotropic fluid is properly chosen, a scale invariant spectrum with large non-Gaussianity can be obtained. In contrast to the results previously obtained in string gas cosmology and holographic cosmology, we find the non-Gaussianity in this context can be k-independent such that it is not suppressed at large scale, which is expected to be testified in future observation.Comment: 13 pages, no figure, typos corrected, references adde