Relative Projectivity and Ideals in Cohomology Rings

AbstractIn this paper we explore one aspect of the relationship between group cohomology and representation theory. For a finite groupGand a fieldkin characteristicp>0, ideals in the cohomology ringH*(G,k) can sometimes be characterized by exact sequences ofkG-modules in much the same way that elements of ExtkGare classically represented by exact sequences. Furthermore the maps on the stable category which represent the exact sequences have functorial properties which mimic the structure of the ideas in the ring. The natural setting for this study is the relative homological algebra for the module category, relative to the subcategory generated by a single module using the tensor product operation

Bond relaxation, electronic and magnetic behavior of 2D metals structures Y on Li(110) surface

We investigated the bond, electronic and magnetic behavior of adsorption Yttrium atoms on Lithium (110) surface using a combination of Bond-order-length-strength(BOLS) correlation and density-functional theory(DFT). We found that adsorption Y atoms on Li(110) surfaces form two-dimensional (2D) geometric structures of hexagon, nonagon, solid hexagonal, quadrangle and triangle. The consistent with the magnetic moment are 6.66{\mu}B, 5.54{\mu}B, 0.28{\mu}B, 1.04{\mu}B, 2.81{\mu}B, respectively. In addition, this work could pave the way for design new 2D metals electronic and magnetic properties

Redox electrolytes in supercapacitors

Most methods for improving supercapacitor performance are based on developments of electrode materials to optimally exploit their storage mechanisms, namely electrical double layer capacitance and pseudocapacitance. In such cases, the electrolyte is supposed to be electrochemically as inert as possible so that a wide potential window can be achieved. Interestingly, in recent years, there has been a growing interest in the investigation of supercapacitors with an electrolyte that can offer redox activity. Such redox electrolytes have been shown to offer increased charge storage capacity, and possibly other benefits. There are however some confusions, for example, on the nature of contributions of the redox electrolyte to the increased storage capacity in comparison with pseudocapacitance, or by expression of the overall increased charge storage capacity as capacitance. This report intends to provide a brief but critical review on the pros and cons of the application of such redox electrolytes in supercapacitors, and to advocate development of the relevant research into a new electrochemical energy storage device in parallel with, but not the same as that of supercapacitors

Waveform-Controlled Terahertz Radiation from the Air Filament Produced by Few-Cycle Laser Pulses

Waveform-controlled Terahertz (THz) radiation is of great importance due to its potential application in THz sensing and coherent control of quantum systems. We demonstrated a novel scheme to generate waveform-controlled THz radiation from air plasma produced when carrier-envelope-phase (CEP) stabilized few-cycle laser pulses undergo filamentation in ambient air. We launched CEP-stabilized 10 fs-long (~ 1.7 optical cycles) laser pulses at 1.8 {\mu}m into air and found that the generated THz waveform can be controlled by varying the filament length and the CEP of driving laser pulses. Calculations using the photocurrent model and including the propagation effects well reproduce the experimental results, and the origins of various phase shifts in the filament are elucidated.Comment: 5pages, 5 figure

Experimental Implementation of Remote State Preparation by Nuclear Magnetic Resonance

We have experimentally implemented remote state preparation (RSP) of a qubit from a hydrogen to a carbon nucleus in molecules of carbon-13 labeled chloroform $^{13}$CHCl$_{3}$ over interatomic distances using liquid-state nuclear magnetic resonance (NMR) technique. Full RSP of a special ensemble of qubits, i.e., a qubit chosen from equatorial and polar great circles on a Bloch sphere with Pati's scheme, was achieved with one cbit communication. Such a RSP scheme can be generalized to prepare a large number of qubit states and may be used in other quantum information processing and quantum computing.Comment: 10 pages,5 PS figure

Generalization and modelling of rigid polyisocyanurate foam reaction kinetics, structural units effect, and cell configuration mechanism

PIR/PUR ratio was derived from differential manipulation of generalized polyisocyanurate kinetic model. The structural unit effects on polymerization of isocyanurate, urethane and urea linkages were evaluated based on Mayo-Lewise tercopolymerization scheme. The cell microstructural configuration model was further developed from profiled FOAMAT reactivity parameters with integrated analysis of cell interface physics. The interstitial border area was defined by interface free energy theory, the shear viscosity was evaluated by foam motion, gas fraction, and partial pressure, and the cell inflation was re-examined by gas-liquid surface tension variability. The cell anisotropic degree, assumed as an aspect ratio of infinitesimal volume elements in cell uniformity, was characterized by equilibrated work increase of surface energy approximated by 2D stretching deformation from sphere cell to spheroid cell. The relationship between pressure and surface tension of elongated cells was also derived from modelling at the same condition of cell deformation

Motor neuron-derived Thsd7a is essential for zebrafish vascular development via the Notch-dll4 signaling pathway.

BackgroundDevelopment of neural and vascular systems displays astonishing similarities among vertebrates. This parallelism is under a precise control of complex guidance signals and neurovascular interactions. Previously, our group identified a highly conserved neural protein called thrombospondin type I domain containing 7A (THSD7A). Soluble THSD7A promoted and guided endothelial cell migration, tube formation and sprouting. In addition, we showed that thsd7a could be detected in the nervous system and was required for intersegmental vessels (ISV) patterning during zebrafish development. However, the exact origin of THSD7A and its effect on neurovascular interaction remains unclear.ResultsIn this study, we discovered that zebrafish thsd7a was expressed in the primary motor neurons. Knockdown of Thsd7a disrupted normal primary motor neuron formation and ISV sprouting in the Tg(kdr:EGFP/mnx1:TagRFP) double transgenic zebrafish. Interestingly, we found that Thsd7a morphants displayed distinct phenotypes that are very similar to the loss of Notch-delta like 4 (dll4) signaling. Transcript profiling further revealed that expression levels of notch1b and its downstream targets, vegfr2/3 and nrarpb, were down-regulated in the Thsd7a morphants. These data supported that zebrafish Thsd7a could regulate angiogenic sprouting via Notch-dll4 signaling during development.ConclusionsOur results suggested that motor neuron-derived Thsd7a plays a significant role in neurovascular interactions. Thsd7a could regulate ISV angiogenesis via Notch-dll4 signaling. Thus, Thsd7a is a potent angioneurin involved in the development of both neural and vascular systems

A Multitarget Land Use Change Simulation Model Based on Cellular Automata and Its Application

Based on the analysis of the existing land use change simulation model, combined with macroland use change driving factors and microlocal land use competition, and through the application of Python language integrated technical approaches such as CA, GIS, AHP, and Markov, a multitarget land use change simulation model based on cellular automata(CA) is established. This model was applied to conduct scenario simulation of land use/cover change of the Jinzhou New District, based on 1:10000 map scale land use, planning, topography, statistics, and other data collected in the year of 1988, 2003, and 2012. The simulation results indicate the following: (1) this model can simulate the mutual transformation of multiple land use types in a relatively satisfactory way; it takes land use system as a whole and simultaneously takes the land use demand in the macrolevel and the land use suitability in the local scale into account; and (2) the simulation accuracy of the model reaches 72%, presenting higher creditability. The model is capable of providing auxiliary decision-making support for coastal regions with the analysis of the land use change driving mechanism, prediction of land use change tendencies, and establishment of land resource sustainable utilization policies

Fabrication and characterization of novel nanostructures based on block copolymer lithography

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2009.Cataloged from PDF version of thesis.Includes bibliographical references.Microphase-separation of block copolymers into periodic nanoscale structures has drawn considerable attention as a method for pattern generation in nanolithography. One of the main challenges is to create complex nanostructures other than closed-packed nanodots or nanoholes with hexagonal symmetry, or parallel nanolines based on block copolymer lithography. In this thesis, we demonstrate two approaches to generate novel structures such as ellipsoids, rings or square array of dots: diblock copolymers templating and triblock terpolymers. Without templating, diblock copolymer can only form spheres, cylinders, or lamellae typically. Triblock terpolymers, on the other hand, can form a larger number of morphologies even without using any template. The use of triblock terpolymers allows the formation of more complex pattern geometries compared to their diblock counterparts. Moreover, since most features in this thesis are made from an organometallic block, they have a high etch contrast and etch resistance compared to triblock terpolymers in which all three blocks contains organic segments, making them useful for pattern transfer. Rings are useful in the magnetic applications, quantum devices, and biosensors. Square symmetry array, which is not found in diblock copolymers, has applications in via formation, magnetic patterned media, and other applications. Besides, we examine the magnetic behavior of the antidot arrays of Co and pseudo-spin-valve structures with periodicity of 26 nm and 40 nm.(cont.) As the inter-hole spacing is decreased, both experiment and simulation results show that the coercivity and switching field distribution is reduced, unlike the behavior seen in films with micron- sized holes. In the multilayer, unlike the continuous film, the NiFe reverses at positive fields due to the strong magnetostatic interactions between the Co and NiFe layers present near the holes. Finally, arrays of high-aspect-ratio single crystal silicon nanowires (SiNWs) have also been fabricate by combining block copolymer lithography and metal assisted etching. These SiNWs may be useful in the application of field-effect biosensors and lithium batteries.by Vivian Peng-Wei Chuang.Ph.D