cssi/SciSciGPT-SciSciNet huggingface dataset:
Analytical model of jet shielding

An analytical model of the shielding of a stationary point noise source by a cylindrical jet is developed. The directivity function is derived which estimates the normalized sound pressure level at a far field receiver. The shielding model is compared to experimental data for a point noise source impinging on an unheated air jet and on a simulated hot air jet. The model compares favorably to measured shielding at receiver locations away from the jet axis. The trend of the estimated shielding diverges from the measured data as the jet axis is approached. Refinement of the model is discussed. STIMATION of aircraft generated noise includes identification not only of the sources of noise on the aircraft, but also of the propagation path between the source and receiver. One of the numerous factors affecting the noise transmission path is shielding of one jet by another. The shielding jet, because of the high temperature and flow speed with respect to the immediate surroundings, acts as a partial barrier between the source and the receiver. The resultant noise reduction not only affects the overall aircraft noise level, but also indicates the possibility of jet engine in- stallation as a means of aircraft noise control. The problem of reflection and transmission of sound by a moving medium has been addressed assuming a plane wave incident on a plane surface.1"4 Ray tracing techniques have been applied to two-dimensional jets5 and cold jets.6 The two- dimensional formulation, for a cylindrical noise source impinging on the shielding jet has been developed.7 The present study is an extension to three dimensions of the previous analysis.7 The model developed consists of the sound field emitted from a stationary, discrete frequency point source, which impinges on a cylinder of locally parallel flow. The temperature and velocity profiles are uniform in the jet at any location downstream of the nozzle. While this model is an idealization of the twin jet, it is felt to incorporate the basic elements essential for a realistic representation; not only of the source, but also of the shielding jet. Model Development Formulation of the Model The mechanisms by which shielding occurs are reflection of sound at the boundary between the jet and the surrounding air and by diffraction around the jet. The noise source is modeled by a stationary discrete frequency point source located at (r0, 0,0). The shielding jet is a cylinder of radius a, and is infinite in extent along the z axis. The temperature and flow velocity are uniform across the cylinder cross section. The model is illustrated in Fig. 1. The expression for acoustic velocity potential is written for two regions; region I is outside the jet, region II is within the jet. In region I (outside the flow) In region II (inside the flow)
Who Gets Designated a Terrorist and Why

This study examines formal terrorism designations by governments through the lens of organization studies research on categorization processes. It is argued that designations hinge on markers from the organizational profile of a militant group. Using cross-sectional data on militant organizations and designations by the United States, the United Kingdom and the European Union, multivariate analyses find that listed organizations do not merely have a track record of violence against a government's citizens, but also tend to target aviation and have an Islamic ideological basis. Mixed support for geopolitical factors is found, but imageries of hegemonic interest are not confirmed. Secondary analyses suggest that newer images of terrorism may replace older ones in classification schemes but further research is needed to know whether this is because of policy adaptation or the effect of spectacular events like September 11th. Language: en
HMC-SIM: A Simulation Framework for Hybrid Memory Cube Devices

The recent advent of stacked die memory and logic technologies has lead to a resurgence in research associated with fundamental architectural techniques. Many architecture research projects begin with ample simulation of the target theoretical functions and approach. However, the logical and physical nature three-dimensional stacked devices, such as the Hybrid Memory Cube (HMC) specification, fundamentally do not align with traditional memory simulation techniques. As such, there currently exists a chasm in the capabilities of modern architectural simulation frameworks. This work introduces a new simulation framework developed specifically for the Hybrid Memory Cube specification. We present a set of novel techniques implemented on an associated development framework that provide an infrastructure to flexibly simulate one or more Hybrid Memory Cube stacked die memory devices attached to an arbitrary core processor. The goal of this development infrastructure is to provide architectural simulation frameworks the ability to begin migrating current banked DRAM memory models to stacked HMC-based designs without a reduction in simulation fidelity or functionality. In addition to the core architecture, this work also presents a series of memory workload test results that represent unit stride and random access memory patterns using the HMC-Sim infrastructure. These evaluations confirm that HMC-Sim can provide insightful guidance in designing and developing highly efficient systems, algorithms, and applications, considering the next-generation three-dimensional stacked memory devices.
Characteristic scales during reionization

One of the key observables of the reionization era is the distribution of neutral and ionized gas. Recently, Furlanetto, Zaldarriaga and Hernquist developed a simple analytic model to describe the growth of H II regions during this era. Here, we examine some of the fundamental simplifying assumptions behind this model and generalize it in several important ways. The model predicts that the ionized regions attain a well-defined characteristic size Rc that ranges from ∼1 Mpc in the early phases to10 Mpc in the late phases. We show that Rc is determined primarily by the bias of the galaxies driving reionization; hence measurements of this scale constrain a fundamental property of the first galaxies. The variance around Rc ,o nthe other hand, is determined primarily by the underlying matter power spectrum. We then show that increasing the ionizing efficiency of massive galaxies shifts Rc to significantly larger scales and decreases the importance of recombinations. These differences can be observed with forthcoming redshifted 21-cm surveys (increasing the brightness temperature fluctuations by up to a factor of 2 on large scales) and with measurements of small-scale anisotropies in the cosmic microwave background. Finally, we show that stochastic fluctuations in the galaxy population only broaden the bubble size distribution significantly if massive galaxies are responsible for most of the ionizing photons. We argue that the key results of this model are robust to many of our uncertainties about the reionization process. Ke yw ords: galaxies: evolution ‐ intergalactic medium ‐ cosmology: theory.
One-pot Friedel-Crafts/Robinson-Gabriel synthesis of oxazoles using oxazolone templates

We report herein a one-pot synthesis of 2,4,5-trisubstituted oxazoles via a Friedel−Crafts/Robinson−Gabriel synthesis using a general oxazolone template. Treatment of the oxazolone template with a range of aromatic nucleophiles provided the highly substituted oxazoles in good yields.
On the Geometry of Cyclic Lattices

Cyclic lattices are sublattices of $$\mathbb Z^N$$ Z N that are preserved under the rotational shift operator. Cyclic lattices were introduced by Micciancio (FOCS, IEEE Computer Society, pp 356---365, 2002) and their properties were studied in the recent years by several authors due to their importance in cryptography. In particular, Peikert and Rosen (Theory of Cryptography, Lecture Notes in Computer Science, vol 3876. Springer, Berlin, pp 145---166, 2006) showed that on cyclic lattices in prime dimensions, the shortest independent vectors problem SIVP reduces to the shortest vector problem SVP with a particularly small loss in approximation factor, as compared to general lattices. In this paper, we further investigate geometric properties of cyclic lattices, proving that a positive proportion of them in every dimension is well-rounded. One implication of our main result is that SVP is equivalent to SIVP on a positive proportion of cyclic lattices in every dimension. As an example, we demonstrate an explicit construction of a family of cyclic lattices on which this equivalence holds. To conclude, we introduce a class of sublattices of $$\mathbb Z^N$$ Z N closed under the action of subgroups of the permutation group $$S_N$$ S N , which are a natural generalization of cyclic lattices, and show that our results extend to all such lattices closed under the action of any $$N$$ N -cycle.
Employment growth from the Small Business Innovation Research program

This paper investigates employment growth in small firms funded by the U.S. Small Business Innovation Research (SBIR) program. Using data collected by the National Research Council for each of five federal agencies, our analysis shows that on average over two-fifths of all projects retained zero employees after completion and over one-third retained only one or two employees. Thus, on average, the direct impact of SBIR funded projects on employment is small, especially when compared to the mean number of employees in the firms. However, there are substantial cross-project differences in the number of retained employees that are explained by differences in the firms and their SBIR projects. We find across funding agencies that projects with intellectual property—patents, copyrights, trademarks, or publications—retained more employees after completion of the project. Also, we find that the public funding of research by the SBIR program is more likely to stimulate employment when the government created a market for the products, processes, or services developed by the research projects.
Polycrystalline Silicon Thin Films For Microelectronic Applications

Polycrystalline silicon thin films with a thickness of 0.5-2μm were grown on 25nm thick Ni prelayers by d.c. magnetron sputtering from a Si target. In contrast to the conventional sputtering, the use of a thin Ni film allows the production of high crystallinity silicon at a temperature of 475°C and higher. The Ni disilicide grains formed at the Ni - growing Si film interface provide sufficient sites for the epitaxial growth of Si. The Si films with resistivity of 102-103Ω-cm possess a carrier lifetime of up to 11μs and a diffusion length of up to 3.4 μm, which makes them applicable to various microelectronic devices. As an example, Schottky diodes fabricated on 0.5μm thick Si films exhibit a forward-to-reverse current ratio of 107. The technique is easily implemented on a variety of substrates.
A new mechanism of electric dipole spin resonance: hyperfine coupling in quantum dots

A recently discovered mechanism of electric dipole spin resonance, mediated by the hyperfine interaction, is investigated experimentally and theoretically. The effect is studied using a spin-selective transition in a GaAs double quantum dot. The resonant frequency is sensitive to the instantaneous hyperfine effective field, revealing a nuclear polarization created by driving the resonance. A device incorporating a micromagnet exhibits a magnetic field difference between dots, allowing electrons in either dot to be addressed selectively. An unexplained additional signal at half the resonant frequency is presented.
Tournaments and Office Politics: Evidence from a Real Effort Experiment

In many environments, tournaments can elicit more effort from workers, except perhaps when workers can sabotage each other. Because it is hard to separate effort, ability and output in many real workplace settings, the empirical evidence on the incentive effect of tournaments is thin. There is even less evidence on the impact of sabotage because real world acts of sabotage are often subtle manifestations of subjective peer evaluation or "office politics." We discuss a real effort experiment in which effort, quality adjusted output and office politics are compared under piece rates and tournaments. Our results suggest that tournaments increase effort only in the absence of office politics. Competitors are more likely to sabotage each other in tournaments and, as a result, workers actually provide less effort simply because they expect to be the victims of sabotage. Adjusting output for quality with the rating of an independent auditor shrinks the incentive effect of the tournament even further since output tends to become more slipshod.
The test, usage and maintenance of power switching subsystems

Unlike signal switching, power switches have significant minimum operational requirements for both voltage and current that affect usage in test programs (TPSs) and self test approaches. In addition to TPS usage and testing considerations, power switches must also be maintained since they have a tendency to build up deposits on their contacts which can degrade the characteristics of the switch. However, there are techniques which can reduce or remove build up of deposits, improving switch operation. These topics are presented in this paper.
X-38 Experimental Aeroheating at Mach 10

Details are provided of a recent effort at the NASA Langley Research Center to extend the experimental aeroheating database for the X-38 program to higher-Mach-number conditions. Global surface heat-transfer distributionswere measured on 0.0177- and 0.0236-scale models of the proposed X-38 Rev 8.3 configuration at Mach 10 in air. The parametrics that were investigated primarily include freestream unit Reynoids numbers of 0.6 to 2.2 x 10 6 /ft and body-flap deflections of 15, 20, and 25 deg for an angle of attack of 40 deg. The model-scale variance was tested to obtain laminar, transitional, and turbulent heating levels on the deflected body flaps. In addition, a limited investigation of forced boundary-layer transition through the use of discrete roughness elements was performed. Comparisons of the present experimental results to computational predictions and previous experimental data were conducted. Laminar, transitional, and turbulent heating levels were observed on the deflected body flap, which compared favorably to the computational results and to the predicted heating based on the flight aerothermodynamic database.
Advanced Propulsion for Future Planetary Spacecraft

Advanced propulsion concepts are evaluated for unmanned exploration class missions to the outer planets. Spacecraft propulsion requirements for these missions are compared with those for previous missions. A major improvement in performance above that offered by current systems is needed to deliver the payloads required by these missions in an acceptable trip time. Advanced pump-fed space storable and cryogenic propulsion systems are evaluated. Nuclear propulsion options considered include the solid core, particle bed, gaseous core, nuclear pulse and nuclear electric concepts. The results of this study reaffirm the superiority of nuclear electric propulsion for this mission category.
Directed oxidative cyclization of 5-hydroxyalkenes with rhenium oxide

Abstract 5-Hydroxyalkenes react with rhenium(VII) oxide (Re2O7) to provide 2-hydroxymethyltetrahydrofurans. Oxidative cyclization occurs with overall syn addition to the alkenes in moderate yields with little tendency toward oxidation of alcohols to carbonyl compounds.
Design-Aware Mask Inspection

Mask inspection has become a major bottleneck in the manufacturing flow taking up as much as 40% of the total mask manufacturing time. In this paper, we explore techniques to improve the reticle inspection flow by increasing its design awareness. We develop an algorithm to locate nonfunctional features in a postoptical proximity correction layout without using any design information. Using this, and the timing information of the design (if available), the smallest defect size that could cause the design to fail is assigned to each reticle feature. The criticality of various reticle features is then used to partition the reticle such that each partition is inspected at a different pixel size and sensitivity so that the false and nuisance defect count is reduced without missing any critical defect. We also develop an analytical model to estimate the false and nuisance defect count. Using those models, our simulation results show that this design-aware mask inspection can reduce the false and nuisance defect count for a critical polysilicon layer from 80 defects down to 49 defects, leading to substantial reduction in defect review load. We also develop a model to estimate first pass yield (FPY) and show that our method can improve the FPY for a polysilicon layer from 11% to 30%. Apart from the polysilicon layer, the potential benefit of this approach is analyzed for active, contact and all the metal/via layers.
Homotopy K3's with several symplectic structures

In this note we prove that, for any n2 N, there exist a smooth 4{manifold, homotopic to a K3 surface, dened by applying the link surgery method of Fintushel{Stern to a certain 2{component graph link, which admits n inequivalent symplectic structures.
Heterojunction Stripe Geometry Lead Salt Diode Lasers Grown By Molecular Beam Epitaxy

Abstract. Lead-rare earth-chalcogenide diode lasers have been grown by molecular beam epitaxy. Emission wavelengths shorter than 5 to 6 Am have been obtained from lead-europium-selenide-telluride (Pb1 -xEuxSeyTe1-y) double heterojunction diode lasers grown lattice-matched to PbTe substrates. Mesa diodes with -25 um wide stripes have been fabricated that have a wide range of single longitudinal mode emission at up to -1 mW/facet output power. These diodes have operated at up to 147 K cw, which to our knowledge is the highest cw operating temperature ever achieved with lead-chalcogenide diode lasers. The wavelength coverage of the PbTe system has so far been extended to 4.06 um cw. Longer wavelength coverage is obtained from double heterojunction diode lasers with Ma1-ySnyTe active regions lattice-matched to (Pb1-ySny)1-xYbxTe confinement layers. I n preliminary studies of diodes with x = 0.034, y = 0.14, the cw emission wavelength varied from 10.7 µm (at 10 K) to 7.1 µm (at 128 K).
Three-Way Complementarities: Performance Pay, Human Resource Analytics, and Information Technology

We test for three-way complementarities among information technology (IT), performance pay, and human resource (HR) analytics practices. We develop a principal--agent model examining how these practices work together as an incentive system that produces a larger productivity premium when the practices are implemented in concert rather than separately. We assess our model by combining fine-grained data on human capital management (HCM) software adoption over 11 years with detailed survey data on incentive systems and HR analytics practices for 189 firms. We find that the adoption of HCM software is greatest in firms that have also adopted performance pay and HR analytics practices. Furthermore, HCM adoption is associated with a large productivity premium when it is implemented as a system of organizational incentives, but has less benefit when adopted in isolation. The system of three-way complements produces disproportionately greater benefits than pairwise interactions, highlighting the importance of including all three complements. Productivity increases significantly when the HCM systems “go live” but not when they are purchased, which can be years earlier. This helps rule out reverse causality as an explanation for our findings. This paper was accepted by Sandra Slaughter, information systems.
Reducing Untruthful Manipulation in Envy-Free Pareto Optimal Resource Allocation

A natural requirement of a resource allocation system is to guarantee fairness to its participants. Fair allocation can be achieved either by distributed protocols known as cake-cutting algorithms or by centralized approaches, which first collect the agents’ preferences and then decide on the allocation. Compared with cake-cutting algorithms, centralized approaches ageless restricted and can therefore achieve more favorable allocations. Our work uses as a starting point a recent centralized algorithm that achieves an envy-free (i.e., fair) and Pareto optimal (i.e., efficient) allocation of multiple divisible goods. In fair allocation algorithms, agents who do not follow the protocol cannot prevent other agents from being allocated a fair share, but in certain situations, agents can increase their own allocation by submitting untruthful preferences. A recent article has shown that the only mechanisms that do not allow such manipulations(i.e., the only incentive-compatible mechanisms) are dictatorial. Nevertheless, we present a method that reduces possible gains from untruthful manipulation. Our mechanism uses a heuristic to approximate optimal manipulations, and compensates agents who submitted suboptimal preferences by increasing their allocation. We empirically demonstrate that when our method is used, the additional benefit that agents can achieve by untruthful manipulation is insignificant, hence they have insignificant incentives to lie.
Application of Zinc Oxide Varistors

This paper deals with the application of ZnO varistors—an area which has not been treated in a systematic way in the literature. The paper starts with a brief description of the fundamental properties comprising the electrical behavior as well as the physics, chemistry, and microstructure of the varistor. These properties then form the basis for defining the application parameters that are directly related to the nonlinear current-voltage characteristics of the varistor. This paper provides a detailed description of these parameters and their relation to microstructure and the processing of the varistor. Finally, a discussion is presented on the reliability of the varistor by considering a grain-boundary defect model which explains both the instability and the stability under use conditions.
T-SPaCS&#x2014;A Two-Level Single-Pass Cache Simulation Methodology

The cache hierarchy's large contribution to total microprocessor system power makes caches a good optimization candidate. To facilitate a fast design-time cache optimization process, we propose a single-pass trace-driven cache simulation methodology-T-SPaCS-for a two-level exclusive cache hierarchy. Direct adaptation of conventional trace-driven cache simulation to two-level caches requires significant storage and simulation time as numerous stacks record cache access patterns for each level one and level two cache combination and each stack is repeatedly processed. T-SPaCS significantly reduces storage space and simulation time using a set of stacks that only record the complete cache access pattern. Thereby, T-SPaCS simulates all cache configurations for both the level one and level two caches simultaneously in a single pass. Experimental results show that T-SPaCS is 21.02X faster on average than sequential simulation for instruction caches and 33.34X faster for data caches. A simplified, but minimally lossy version of T-SPaCS (simplified-T-SPaCS) increases the average simulation speedup to 30.15X for instruction caches and 41.31X for data caches. We leverage T-SPaCS and simplified-T-SPaCS for determining the lowest energy cache configuration to quantify the effects of lossiness and observe that T-SPaCS and simplified-T-SPaCS still find the lowest energy cache configuration as compared to exact simulation.
Understanding the Factors Influencing Ski Destination Choice: A Means-End Analytic Approach

A variety of factors have been examined to understand and explain destination choice behavior, ranging from the relatively tangible attributes of products, to the intangible benefits, needs, and pe...
On memory in exponentially expanding spaces

We examine the degree to which uctuating dynamics on exponentially expanding spaces remember initial conditions. In de Sitter space, the global late-time cong
The synthesis of 4-deazaformycin A.

The preparation of 4-deazaformycin A has been achieved. The synthesis features the condensation of a suitably substituted, lithiated 4-picoline with 2,3,5-tri-O-benzyl-d-ribonolactone, dehydration of the resulting hemiacetal, and ionic hydrogenation, followed by manipulation of the protecting groups and subsequent ring closure with the formation of 7-amino-3-(β-d-ribofuranosyl)pyrazolo[3,4-c]pyridine.
Cell Death Pathways in Photodynamic Therapy of Cancer

Photodynamic therapy (PDT) is an emerging cancer therapy that uses the combination of non-toxic dyes or photosensitizers (PS) and harmless visible light to produce reactive oxygen species and destroy tumors. The PS can be localized in various organelles such as mitochondria, lysosomes, endoplasmic reticulum, Golgi apparatus and plasma membranes and this sub-cellular location governs much of the signaling that occurs after PDT. There is an acute stress response that leads to changes in calcium and lipid metabolism and causes the production of cytokines and stress response mediators. Enzymes (particularly protein kinases) are activated and transcription factors are expressed. Many of the cellular responses center on mitochondria and frequently lead to induction of apoptosis by the mitochondrial pathway involving caspase activation and release of cytochrome c. Certain specific proteins (such as Bcl-2) are damaged by PDT-induced oxidation thereby increasing apoptosis, and a build-up of oxidized proteins leads to an ER-stress response that may be increased by proteasome inhibition. Autophagy plays a role in either inhibiting or enhancing cell death after PDT.
Autonomous Underwater Vehicle trajectory design coupled with predictive ocean models: A case study

Data collection using Autonomous Underwater Vehicles (AUVs) is increasing in importance within the oceanographic research community. Contrary to traditional moored or static platforms, mobile sensors require intelligent planning strategies to maneuver through the ocean. However, the ability to navigate to high-value locations and collect data with specific scientific merit is worth the planning efforts. In this study, we examine the use of ocean model predictions to determine the locations to be visited by an AUV, and aid in planning the trajectory that the vehicle executes during the sampling mission. The objectives are: a) to provide near-real time, in situ measurements to a large-scale ocean model to increase the skill of future predictions, and b) to utilize ocean model predictions as a component in an end-to-end autonomous prediction and tasking system for aquatic, mobile sensor networks. We present an algorithm designed to generate paths for AUVs to track a dynamically evolving ocean feature utilizing ocean model predictions. This builds on previous work in this area by incorporating the predicted current velocities into the path planning to assist in solving the 3-D motion planning problem of steering an AUV between two selected locations. We present simulation results for tracking a fresh water plume by use of our algorithm. Additionally, we present experimental results from field trials that test the skill of the model used as well as the incorporation of the model predictions into an AUV trajectory planner. These results indicate a modest, but measurable, improvement in surfacing error when the model predictions are incorporated into the planner.
HST Photometry of Dwarf Elliptical Galaxies in Coma, and an Explanation for the Alleged Structural Dichotomy between Dwarf and Bright Elliptical Galaxies

As part of a research program exploring how and why dwarf elliptical (dE) galaxies depart from the fundamental plane defined by luminous elliptical (E) galaxies, we have analyzed archival Hubble Space Telescope F606W images of a sample of 18 dE galaxy candidates in the Coma Cluster. We model the full radial extent of their light profiles by simultaneously fitting a point-spread function (PSF) convolved Sersic R1/n model and, when necessary, either a central point source or a central PSF-convolved Gaussian. Nucleation was detected in all but two of our final sample of 15 dE galaxies. When detected, the luminosities of the central component, Lnuc, scale with the host galaxy luminosity Lgal such that Lnuc = 104.76±0.10(Lgal/107)0.87±0.26. We confirm that the light profiles of the underlying host galaxies display systematic departures from an exponential model that are correlated with the model-independent host galaxy luminosity and are not due to biasing from the nuclear component. The Pearson correlation coefficient between log n and central galaxy surface brightness μ0 (excluding the flux from extraneous central components) is -0.83 at a significance level of 99.99%. Excluding one outlier, the Pearson correlation coefficient between the logarithm of the Sersic index n and the host galaxy magnitude is -0.77 at a significance of 99.9%. We explain the observed relationship between dE galaxy luminosity and the inner logarithmic profile slope γ' as a by-product of the correlation between luminosity and Sersic index n. Including, from the literature, an additional 232 dE and E galaxies spanning 10 mag in absolute magnitude M, the dE galaxies are shown to display a continuous sequence with the brighter E galaxies, such that μ0 brightens linearly with M until core formation causes the most luminous (MB -20.5) E galaxies to deviate from this relation. The different behavior of dE and E galaxies in the M-μe (and M-μe) diagram and the μe–log Re diagram has nothing to do with core formation and is in fact expected from the continuous and linear relation between M and μ0, and M and log n.
Comparability of Earnings in Scandinavian Countries: The Impact of Mandatory IFRS Adoption and Stock Exchange Consolidations

ABSTRACT: This study examines the impact on the comparability of earnings of two important events that occurred in 2005 in the Scandinavian region: the European Union-mandated adoption of International Financial Reporting Standards (IFRS) and the mergers between the three national exchanges of Denmark, Finland, and Sweden. Our tests follow two approaches. The first approach relies on mean-centered earnings/price multiples following Land and Lang (2002) to determine if the multiples converge in the 2005–2008 period. Our results show that all countries except Finland experienced a lower mean-centered earnings/price ratio in the 2005–2008 period. Additionally, in the 2005–2008 period, the mean-centered earnings/price ratio in Norway deviates from the region's mean more than it deviates from the mean in Finland, Denmark, and Sweden, even after controlling for other firm and country factors. Our second approach uses a firm-year comparability measure (De Franco et al. 2011) calculated during the 2001–2004 and 2...
Analysis of the 802.11e enhanced distributed channel access function

We propose an analytical model for the performance analysis of the enhanced distributed channel access (EDCA) function of the IEEE 802.11e standard. The proposed discrete-time Markov chain (DTMC) model incorporates the main quality-of-service (QoS) features of 802.11e, namely, contention window (CW), arbitration interframe space (AIFS), and transmit opportunity (TXOP) differentiation. Due to its specific design, the proposed DTMC model jointly considers the state of the medium access control (MAC) layer buffer and the MAC differentiation mechanisms which facilitates a novel performance analysis framework at an arbitrary traffic load. Analytical and simulation results are compared to demonstrate the accuracy of the proposed approach for varying traffic load, EDCA parameters, and MAC layer buffer space.
An Explicit Derivation of the Möbius Function for Bruhat Order

We give an explicit nonrecursive complete matching for the Hasse diagram of the strong Bruhat order of any interval in any Coxeter group. This yields a new derivation of the Mobius function, recovering a classical result due to Verma.
Trickling Filtration Design and Performance

Statistical correlation of filter performance to depth, hydraulic loading, and media characteristics is presented; effects of oxygen and temperature on filter performance; new design formulations. ...
Flexible Matrix Composite Skins for One-dimensional Wing Morphing

Morphing aircraft wings require flexible skins that undergo large strains, have low in-plane stiffness, and high out-of-plane stiffness to carry aerodynamic loads. For some morphing applications deformation and low stiffness in the flexskin is required in one direction. In these cases, a flexible matrix composite (FMC) skin is proposed as a possible solution. A FMC comprises of stiff fibers embedded in a soft, high-strain capable matrix material. The matrix-dominated direction is aligned with the morphing direction. This allows the skin to undergo large strain at low energy cost. However, the high-stiffness in the fiber-dominated direction allows application of pretension along this direction, without rupture, and is critical for the membrane skin to carry out-of-plane pressure loads without excessive deformation. An analysis for a FMC skin panel is developed and validated against experiment. The analysis is used to conduct design studies. Comparison of the FMC skin to a matrix-only skin illustrates the i...
Using Coupled Transmission Lines to Generate Impedance-Matched Pulses Resembling Charged Device Model ESD

A quarter-wave directional coupler plus ordinary transmission line pulsing (TLP) can create short pulses resembling charged device model (CDM) electrostatic discharge (ESD). Pulse rise time often relates to the coupler's center frequency and can thereby be stabilized. It is shown that for a voltage step of a given size, yet with arbitrary waveform, the net amount of coupled charge (the charge packet) is constant and depends only on fixed coupler parameters. This property of Z-matched coupled lines has wider implications. High-voltage couplers can be made from coaxial cable or from stripline. Some of these designs are described, tested, and compared to computer simulations of coupled lines
α-Vinylic amino acids : occurrence, asymmetric synthesis, and biochemical mechanisms

Abstract This report presents an overview of the family of naturally occurring ‘vinylic’ amino acids, namely those that feature a C–C double bond directly attached to the α-carbon, along the side chain. Strategies that have been brought to bear on the stereocontrolled synthesis of these olefinic amino acids are surveyed. The mechanistic diversity by which such ‘vinylic triggers’ can be actuated in a PLP (pyridoxal phosphate) enzyme active site is then highlighted by discussion of vinylglycine (VG), its substituted congeners, particularly AVG [4E-(2′-aminoethoxy)vinylglycine], and a naturally occurring VG-progenitor, SMM [(S)-methylmethionine].
Intramolecular coupling between cyclohexadiene–Fe(CO)3 complexes and pendant alkenes: formation of azaspiro[5,5]undecane derivatives

Abstract A new methodology for making stereodefined 2-azaspiro[5,5]undecan-1-one (δ-lactam) derivatives was developed by intramolecular coupling between cyclohexadiene–Fe(CO) 3 moiety and pendant olefins. δ-Lactams were found more difficult to form than γ-lactams, thus resulting in poorer yields and requiring longer reaction times. By introducing an ester group on the pendant olefin, increased yield was achieved.
Asymmetric Synthesis of α,α-Difluoro-β-amino Acid Derivatives from Enantiomerically Pure N-tert-Butylsulfinimines

Addition of the Reformatsky reagent derived from ethyl bromodifluoroacetate to alkyl- and aryl-substituted N-tert-butylsulfinimines furnishes β-tert-butylsulfinamyl-β-substituted α,α-difluoroproponiates in diastereomeric ratios ranging from 80:20 to 95:5. The diastereomers are easily separated and the enantiomerically pure, protected β-amino esters are readily transformed to the corresponding acid, amide, and amine derivatives as useful synthons for medicinal chemistry targets.
Corrugated silicon platelet feed horn array for CMB polarimetry at 150 GHz

Next generation cosmic microwave background (CMB) polarization anisotropy measurements will feature focal plane arrays with more than 600 millimeter-wave detectors. We make use of high-resolution photolithography and wafer-scale etch tools to build planar arrays of corrugated platelet feeds in silicon with highly symmetric beams, low cross-polarization and low side lobes. A compact Au-plated corrugated Si feed designed for 150 GHz operation exhibited performance equivalent to that of electroformed feeds: ~ -0.2 dB insertion loss, < -20 dB return loss from 120 GHz to 170 GHz, < -25 dB side lobes and < -23 dB cross-polarization. We are currently fabricating a 50mm diameter array with 84 horns consisting of 33 Si platelets as a prototype for the SPTpol and ACTpol telescopes. Our fabrication facilities permit arrays up to 150mm in diameter.
Anticipated emotions as guides to choice.

When making decisions, people often anticipate the emotions they might experience as a result of the outcomes of their choices. In the process, they simulate what life would be like with one outcome or another. We examine the anticipated and actual pleasure of outcomes and their relation to choices people make in laboratory studies and real-world studies. We offer a theory of anticipated pleasure that explains why the same outcome can lead to a wide range of emotional experiences. Finally, we show how anticipated pleasure relates to risky choice within the framework of subjective expected pleasure theory.
Dyskinesia and neuroleptic exposure in elderly psychiatric inpatients.

A wide variation in prevalence rates of tardive dyskinesia and spontaneous orofacial dyskinesia has been reported in the elderly. To clarify these discrepancies, we studied 45 patients over the age of 60 years admitted to a short-term psychiatr unit. Standardized criteria for the diagnosis of dyskinesia were used. We found a rate of tardive dyskinesia of only 21% (7/33) in our patients having a history of neuroleptic exposure. We found no cases (0/12) of spontaneous orofacial dysknesia. There was a significant association between tardive dyskinesia and psychiatric diagnosis, with the highest rate of tardive dyskinesia in those patients with schizophrenic disorders, followed by those with organic disorders and mood disorders, respectively. There was also a significant association between the presence of tardive dyskinesia and radio-graphic evidence of cortical atrophy, and a trend towards an association with leukoencephalopathy. Our results suggest that published rates of tardive and spontaneous dyskinesia...
Modulation of the Reactivity Profile of IBX by Ligand Complexation: Ambient Temperature Dehydrogenation of Aldehydes and Ketones to α,β-Unsaturated Carbonyl Compounds

We have recently reported[1, 2] that the use of IBX (oiodoxybenzoic acid)[3] represents a highly adept method for accessing the coveted, yet synthetically challenging, , unsaturated carbonyl motif by effecting the dehydrogenation of ketones and aldehydes at elevated temperatures. Our interest[4±8] in this unique iodine( ) species has grown further owing to the tantalizing discovery that its chemistry can be modulated by complexation with a variety of ligands, thus leading to dramatic changes in its reactivity profile.[2,8a, 10] The ligand appended to IBX not only allows moderation of the reagent×s reactivity, but also differentiation between reaction pathways when a number of alternatives are available (Scheme 1).[2] Herein, we report the discovery and elucidation of this new and exciting concept and its application to the
Carbonylation of Aryl Chlorides with Oxygen Nucleophiles at Atmospheric Pressure. Preparation of Phenyl Esters as Acyl Transfer Agents and the Direct Preparation of Alkyl Esters and Carboxylic Acids

A mild, functional group tolerant method of the preparation of phenyl esters from aryl chlorides via palladium-catalyzed carbonylation is described using atmospheric pressure of carbon monoxide. Phenyl esters are shown to be useful acylating agents, delivering libraries of carbonyl derivatives, including alkyl, allyl and thioesters, under very mild conditions. Direct preparation of alkyl esters and carboxylic acids is also demonstrated, providing the first method for the preparation of methyl and ethyl esters from aryl chlorides without pressured reactors.
Two-career chaos

The following essay by Lisa Tauxe describes the difficult personal decisions facing a dual-career couple as they prepare for a job-related move that will uproot their family and one spouse's career.
Elimination diets for the diagnosis and treatment of food allergy

T HE importance of food sensitivity in many allergic diseases has long been recognized, but it was not until 1925 that a systematic method of determining the causative foods by test diets was reported by R0we.l His method was to place the patient for periods of a week or two on a series of diets each rigidly limited to a small number of foods and to observe the effects of these diets on the patient’s symptoms. An effort was made to exclude foods to which many patients were sensitive and yet to maintain a diet which was adequate for a limited time. If symptoms were not relieved by use of the first diet, a second test diet was tried. If symptoms were relieved, new foods were added gradually in the succeeding weeks, excluding any that caused a recurrence of symptoms. Wheat, eggs, and milk were not added for several weeks. The building up of a satisfactory diet may take a long time with possible danger resulting from a restricted diet. In order to overcome the slight deficiency of minerals, especially calcium, in Rowe’s diet, Dale and Thornburg devised two diets composed of twenty-one and twenty-three mutually exclusive proteins, the unusual being used in preference to the common foods. Care was taken to include the foods which were rich in mineral and vitamin content,. Though these diets were adequate, the diagnostic advantage of Rowe’s limited diets was lost to some extent as the individual effect of each food could not be so carefully observed. More recently Rowe3 has published a revision of his diets with tables showing the nutritive value of each, including the content of calcium, phosphorus, iron, and vitamins.
Parallel image subtraction using a phase-conjugate Michelson interferometer.

A phase-conjugate Michelson interferometer using an internally self-pumped barium titanate crystal as reflectors has been constructed to perform parallel image subtraction, intensity inversion, and exclusive or logic operation. These operations are independent of the optical path differences and phase aberration.
Water Transport in Multilayer Organic Coatings

Protective multilayer coatings are designed, with each layer providing distinctive features to reduce the transport of water, ions, and oxygen from the environment to the substrate. The top coat provides the barrier, whereas the base coat/primer provides adhesion to the substrate as well as galvanic or passivation protection. The change in the coating capacitance during the ingress or egress of water is associated with the change in the dielectric property of the coating and can be monitored using the electrochemical impedance spectroscopy response of a high-frequency signal applied to the coating. The wetting and drying behaviors of epoxy and urethane single-layer coatings and epoxy primer/urethane top-coat two-layer coatings were experimentally measured. A hydrophilic room-temperature ionic liquid was used to simulate drying while maintaining a nonaqueous electrical contact to the coating. Embedded electrodes were used to access the top-coat-primer interface in the two-layer coating. Mathematical models were developed based on Fick's second law for water transport in single-layer and two-layer coatings. Comparison of measured and simulated water uptake demonstrated that the assumptions used in the single-layer model were appropriate while the assumptions used for transport across the interface between the layers in the two-layer coating were inadequate.
Localized precipitation and runoff on Mars

[1] We use the Mars Regional Atmospheric Modeling System (MRAMS) to simulate lake storms on Mars, finding that intense localized precipitation will occur for lake size ≥103 km2. Mars has a low-density atmosphere, so deep convection can be triggered by small amounts of latent heat release. In our reference simulation, the buoyant plume lifts vapor above condensation level, forming a 20 km high optically thick cloud. Ice grains grow to 200 μm radius and fall near (or in) the lake at mean rates up to 1.5 mm h−1 water equivalent (maximum rates up to 6 mm h−1 water equivalent). Because atmospheric temperatures outside the surface layer are always well below 273 K, supersaturation and condensation begin at low altitudes above lakes on Mars. In contrast to Earth lake-effect storms, lake storms on Mars involve continuous precipitation, and their vertical velocities and plume heights exceed those of tropical thunderstorms on Earth. For lake sizes 102.5 to 103.5 km, plume vertical velocity scales linearly with lake area. Convection does not reach above the planetary boundary layer for lakes ≪103 km2 or for atmospheric pressure >O(102) mbar. Instead, vapor is advected downwind with little cloud formation. Precipitation occurs as snow, and the daytime radiative forcing at the land surface due to plume vapor and storm clouds is too small to melt snow directly (<+10 W m−2). However, if orbital conditions are favorable, then the snow may be seasonally unstable to melting and produce runoff to form channels. We calculate the probability of melting by running thermal models over all possible orbital conditions and weighting their outcomes by probabilities given by long-term integrations of the chaotic diffusion of solar system orbital elements. With this approach, we determine that for an equatorial vapor source, sunlight 15% fainter than at present and snowpack with albedo 0.28 (0.35), melting may occur with 4% (0.1%) probability. This rises to 56% (12%) if the ancient greenhouse effect was modestly (6 K) greater than today.
Environmental policy in a linear city model of product differentiation

This paper analyzes how a tax/subsidy policy affects consumers' behavior when choosing between green (pollution-free goods) and conventional products, and its effects on welfare when a proportion of consumers have strong preferences for green goods. We analyze a Hotelling's linear city model where final products by two firms are symmetric in all dimensions except for the externality their production process generates. Our efficiency comparisons suggest that, under a setting of horizontal product differentiation, an environmental regulation (either on polluting firms or consumers buying their products) yields higher social welfare than the absence of policy. Moreover, the proportion of consumers who prefer green products affects the welfare gains from a subsidy or tax policy.
Residual Stress/Strain in Three-Row, Countersunk, Riveted Lap Joints

The stress/strain variations from the riveting process to the tensile loading stage in lap joints with three-row countersunk rivets were studied experimentally and numerically. Three different forces were used in the riveting process. After releasing the rivet squeeze forces, the lap joints were then loaded in tension. Three-dimensional finite element models were developed to simulate the experimental setup. The material elasto-plastic constitutive relationship and geometric non-linear properties, as well as, nonlinear contact boundary conditions were included in the numerical simulations. The numerical modeling techniques were validated using experimental data. The effect of the residual stress on the stress variations, along a prescribed path during the tensile loading stage, is discussed. Full-field contours of the residual minimum principal stress induced by the riveting process, and the maximum principal stress during the tensile loading stage are also analyzed. The aim of this research is to develop an accurate three-dimensional numerical technique to study the complex stress and strain distributions induced by the entire loading sequence, and to use this information to more accurately predict the fatigue life of fuselage lap joints.