cssi/SciSciGPT-SciSciNet huggingface dataset:
Optical magnetic mirrors without metals

The reflection of an optical wave from metal, arising from strong interactions between the optical electric field and the free carriers of the metal, is accompanied by a phase reversal of the reflected electric field. A far less common route to achieving high reflectivity exploits strong interactions between the material and the optical magnetic field to produce a “magnetic mirror” that does not reverse the phase of the reflected electric field. At optical frequencies, the magnetic properties required for strong interaction can be achieved only by using artificially tailored materials. Here, we experimentally demonstrate, for the first time to the best of our knowledge, the magnetic mirror behavior of a low-loss all-dielectric metasurface at infrared optical frequencies through direct measurements of the phase and amplitude of the reflected optical wave. The enhanced absorption and emission of transverse-electric dipoles placed close to magnetic mirrors can lead to exciting new advances in sensors, photodetectors, and light sources.
Conceptual models for determining information requirements

For years, we who are interested in data processing have had a vague notion that one of the problems facing managers today is the lack of information. "If only I had known . . ." is a familiar phrase to all of us. Most of us would like to cause that phrase to become unfamiliar. Unfortunately, very few people, if any, have been able to state very explicitly how we should go about filling the information void. Progress in developing a methodology for designing management information systems has been slow.
MARKET POWER AND ASYMMETRY IN FARM-RETAIL PRICE TRANSMISSION

A finite mixture model is used to examine whether price asymmetries exist in U.S. fresh strawberry markets. Two distinct pricing regimes are identified. Results show that price asymmetries exist only at 34 percent of the cases and market power has played an important role in generating such asymmetric price relationships.
MicroRNAs can generate thresholds in target gene expression

Alexander van Oudenaarden and colleagues examine microRNA-mediated regulation of gene expression using single-cell measurements of a target gene's expression. They find that microRNAs can repress gene expression either as a switch or through fine-tuning and that the strength of repression can vary widely between cells.
Micro-to-macro fluidic interconnectors with an integrated polymer sealant

This paper presents the design, fabrication and testing results of inserting a polymer sealant (Mylar) into a micro-to-macro fluidic interconnection. Two processes, discrete and integrated Mylar sealant, have been developed by means of post-fabrication after the mircofluidic components such as micro-channels and micro-chambers are constructed. The integrated process utilizes microfabrication techniques such that batch processing is feasible and the sealant dimensions can be precisely controlled. The discrete process takes advantage of easy and simple processing and is compatible with most microfluidic systems without any extra wafer-level micromachining process. In both processes, macroscale capillary tubes with a diameter of 320 µm have been successfully connected to microscale channels with the help of the Mylar. Both leakage and pull-out tests are conducted and successfully demonstrate the functionality of the interconnectors. The leakage test shows that no leakage is observed up to 190 kPa and the pull-out test proves 100% survival rate under a pulling force of 2 N. (Some figures in this article are in colour only in the electronic version)
Fast approximate energy minimization via graph cuts

Many tasks in computer vision involve assigning a label (such as disparity) to every pixel. A common constraint is that the labels should vary smoothly almost everywhere while preserving sharp discontinuities that may exist, e.g., at object boundaries. These tasks are naturally stated in terms of energy minimization. The authors consider a wide class of energies with various smoothness constraints. Global minimization of these energy functions is NP-hard even in the simplest discontinuity-preserving case. Therefore, our focus is on efficient approximation algorithms. We present two algorithms based on graph cuts that efficiently find a local minimum with respect to two types of large moves, namely expansion moves and swap moves. These moves can simultaneously change the labels of arbitrarily large sets of pixels. In contrast, many standard algorithms (including simulated annealing) use small moves where only one pixel changes its label at a time. Our expansion algorithm finds a labeling within a known factor of the global minimum, while our swap algorithm handles more general energy functions. Both of these algorithms allow important cases of discontinuity preserving energies. We experimentally demonstrate the effectiveness of our approach for image restoration, stereo and motion. On real data with ground truth, we achieve 98 percent accuracy.
BV-GENERATORS AND LIE ALGEBROIDS

Let be a Gerstenhaber algebra generated by and . Given a degree -1 operator D on , we find the condition on D that makes a BV-algebra. Subsequently, we apply it to the Gerstenhaber or BV algebra associated to a Lie algebroid and obtain a global proof of the correspondence between BV-generators and flat connections.
Approximately universal codes over slow-fading channels

Performance of reliable communication over a coherent slow-fading multiple-input multiple-output (MIMO) channel at high signal-to-noise ratio (SNR) is succinctly captured as a fundamental tradeoff between diversity and multiplexing gains. This paper studies the problem of designing codes that optimally tradeoff the diversity and multiplexing gains. The main contribution is a precise characterization of codes that are universally tradeoff-optimal, i.e., they optimally tradeoff the diversity and multiplexing gains for every statistical characterization of the fading channel. This characterization is referred to as approximate universality; the approximation is in the connection between error probability and outage capacity with diversity and multiplexing gains, respectively. The characterization of approximate universality is then used to construct new coding schemes as well as to show optimality of several schemes proposed in the space-time coding literature.
Optimal linear representations of images for object recognition

Although linear representations are frequently used in image analysis, their performances are seldom optimal in specific applications. This paper proposes a stochastic gradient algorithm for finding optimal linear representations of images for use in appearance-based object recognition. Using the nearest neighbor classifier, a recognition performance function is specified and linear representations that maximize this performance are sought. For solving this optimization problem on a Grassmann manifold, a stochastic gradient algorithm utilizing intrinsic flows is introduced. Several experimental results are presented to demonstrate this algorithm.
Note on graviton MHV amplitudes

Two new formulas which express n-graviton MHV tree amplitudes in terms of sums of squares of n-gluon amplitudes are discussed. The first formula is derived from recursion relations. The second formula, simpler because it involves fewer permutations, is obtained from the variant of the Berends, Giele, Kuijf formula given in Arxiv:0707.1035.
A comparison of physical properties and fuel cell performance of Nafion and zirconium phosphate/Nafion composite membranes

Abstract The physiochemical properties of Nafion 115 and a composite Nafion 115/zirconium phosphate (∼25 wt.%) membranes are compared. The composite membrane takes up more water than Nafion at the same water activity. However, the proton conductivity of the composite membrane is slightly less than that for Nafion 115. Small angle X-ray scattering shows that the hydrophilic phase domains in the composite membrane are spaced further apart than in Nafion 115, and the composite membrane shows less restructuring with water uptake. Despite the lower proton conductivity of the composite membranes they display better fuel cell performance than Nafion 115 when the fuel cell is operated at reduced humidity conditions. It is suggested that the composite membrane has a greater rigidity that accounts for its improved fuel cell performance.
Evidence for heterotic - type I string duality

Abstract A study is made of the implications of heterotic string T -duality and extended gauge symmetry for the conjectured equivalence of heterotic and Type I superstrings. While at first sight heterotic string world-sheet dynamics appears to conflict with Type I perturbation theory, a closer look shows that Type I perturbation theory “miraculously” breaks down, in some cases via novel mechanisms, whenever the heterotic string has massless particles not present in Type I perturbation theory. This strongly suggests that the two theories actually are equivalent. As further evidence in the same direction, we show that the Dirichlet one-brane of Type I string theory has the same world-sheet structure as the heterotic string.
Social Security and the Retirement and Savings Behavior of Low Income Households.

In this paper, we develop and estimate a model of retirement and savings incorporating limited borrowing, stochastic wage offers, health status and survival, social security benefits, Medicare and employer-provided health insurance coverage, and intentional bequests. The model is estimated on a sample of relatively poor households from the first three waves of the Health and Retirement Study (HRS), for whom we would expect social security income to be of particular importance. The estimated model is used to simulate the responses to changes in social security rules, including changes in benefit levels, in the payroll tax, in the social security earnings tax and in early and normal retirement ages. Welfare and budget consequences are estimated.
Nanoparticle catalysts for nitrile hydration

Abstract The transition metal-catalyzed hydration of nitriles is an efficient route to amides, which are important synthetic building blocks. Many heterogeneous and homogeneous catalysts have been explored for this reaction, but there are drawbacks to each type of catalyst. Nanoparticle (NP) catalysis is a potential bridge between heterogeneous and homogeneous catalysis, frequently combining the easy separation of heterogeneous catalysts with the tunability of homogeneous catalysts. Although the field of NP catalysts is relatively new, NP catalysts have been explored for a variety of reactions, including a number of nitrile hydration reactions. This review makes a thorough assessment of these nitrile hydration reactions.
The Solution Economy: Getting Everybody Into the Act

This article is a review of William D. Eggers and Paul Macmillan book, The Solution Revolution: How Business, Government, and Social Enterprises Are Teaming Up to Solve Society’s Toughest Problems (Boston, MA: Harvard Business Review Press, 2013, 292 pages).
Chosen-Ciphertext security from slightly lossy trapdoor functions

Lossy Trapdoor Functions (LTDFs), introduced by Peikert and Waters (STOC 2008) have been useful for building many cryptographic primitives. In particular, by using an LTDF that loses a (1−1/ω(logn)) fraction of all its input bits, it is possible to achieve CCA security using the LTDF as a black-box. Unfortunately, not all candidate LTDFs achieve such a high level of lossiness. In this paper we drastically lower the lossiness required to achieve CCA security, showing that an LTDF that loses only a noticeable fraction of a single bit can be used in a black-box way to build CCA-secure PKE. To show our result, we build on the recent result of Rosen and Segev (TCC 2009) that showed how to achieve CCA security from functions whose products are one-way on particular types of correlated inputs. Lastly, we give an example construction of a slightly lossy TDF based on the assumption that it is hard to distinguish the product of two primes from the product of three primes.
Unusual C25 steroids produced by a sponge-derived Penicillium citrinum

[structure: see text] Structurally unique steroids, isocyclocitrinol A (1) and 22-acetylisocyclocitrinol A (2), were isolated from the extract of a saltwater culture of sponge-derived Penicilliun citrinum. The structures were established by analysis of 1D and 2D NMR data. The absolute structures were determined on the basis of X-ray structure analysis and application of modified Mosher's method. Furthermore, the structure of cyclocitrinol (3a) previously isolated from a terrestrial P. citrinum was revised as 3b. Compounds 1 and 2 showed weak antibacterial activity against Staphylococcus epidermidis and Enterococcus durans.
Simulation of interference between Earth stations and Earth-orbiting satellites

It is often desirable to determine the potential for radio frequency interference between Earth stations and orbiting spacecraft. This information can be used to select frequencies for radio systems to avoid interference or it can be used to determine if coordination between radio systems is necessary. A model is developed that will determine the statistics of interference between Earth stations and elliptical orbiting spacecraft. The model uses orbital dynamics, detailed antenna patterns, and spectral characteristics to obtain accurate levels of interference at the victim receiver. The model is programmed into a computer simulation to obtain long term statistics of interference. Two specific examples are shown to demonstrate the model. The first example is a simulation of interference from a fixed-satellite Earth station to an orbiting scatterometer receiver. The second example is a simulation of interference from Earth exploration-satellites to a deep space Earth station. >
An extended BNF for specifying the syntax of declarations

The syntax of ALGOL is specified in its defining report by a grammar whose rules are given in Backus-Naur Form (BNF). Because of the need for precision in the specification of complex systems, BNF has been used to record the syntax of many other programming languages. The rules of BNF are equivalent to context-free production rules. However, due to its declarations, ALGOL is context-dependent, and its syntax cannot be fully specified by a grammar limited to context-free rules. Other grammars for ALGOL are more compact than the BNF of the defining report, but they are generatively no more powerful. Because of this context-dependency of declarations, even an assembly language cannot be fully specified in BNF.
Microfluidic Preparative Free-Flow Isoelectric Focusing: System Optimization for Protein Complex Separation

Isoelectric Focusing (IEF) is the first step for two-dimensional (2D) gel electrophoresis and plays an important role in sample purification for proteomics. However, biases in protein size and pI resolution, as well as limitations in sample volume, gel capacity, sample loss, and experimental time, remain challenges. In order to address some of the limitations of traditional IEF, we present a microfluidic free flow IEF (FF-IEF) device for continuous protein separation into 24 fractions. The device reproducibly establishes a nearly linear pH gradient from 4 to 10. Optimized dynamic coatings of 4% poly (vinyl) alcohol (PVA) minimize peak broadening by transverse electrokinetic flows. Even though the device operates at high electric fields (up to 370V/cm) efficient cooling maintains solution temperature inside the separation channel controllably in the range 2 – 25 °C. Protein samples with a dynamic concentration range between µg/mL to mg/mL can be loaded into the micro device at a flow rate of 1 mL/hr and residence time of ~12 min. By using a protein complex of 9 proteins and 13 isoforms, we demonstrate improved separation with the FF-IEF system over traditional 2D gel electrophoresis. Device to device reproducibility is also illustrated through the efficient depletion of the albumin and hemoglobin assays. Post-device sample concentrations result in a 10 to 20-fold increase, which allow for isolation and detection of low abundance proteins. The separation of specific proteins from a whole cell lysate is demonstrated as an example. The micro device has the further benefits of retaining high molecular weight proteins, providing higher yield of protein that has a broader range in pI, and reducing experimental time compared to conventional IEF IGP gel strip approaches.
Catalysts for the living insertion polymerization of alkenes: access to new polyolefin architectures using Ziegler-Natta chemistry.

Coordination–insertion polymerization systems have long been superior to their anionic, cationic, and radical polymerization counterparts with regard to stereochemical control. However, until five years ago, these metal-based insertion methods were inferior to ionic and radical mechanisms in the category of living polymerization, which is simply a polymerization that occurs with rapid initiation and negligible chain termination or transfer. In the last half decade, the living insertion polymerization of unactivated olefins has emerged as a powerful tool for the synthesis of new polymer architectures. Materials available today by this route range from simple homopolymers such as linear and branched polyethylene, to atactic or tactic poly(α-olefins), to end-functionalized polymers and block copolymers. This review article summarizes recent developments in this rapidly growing research area at the interface of synthetic and mechanistic organometallic chemistry, polymer chemistry, and materials science. While special emphasis is placed on polymer properties and novel polymeric architectures, most of which were inaccessible just a decade ago, important achievements with respect to ligand and catalyst design are also highlighted.
ppiTrim: constructing non-redundant and up-to-date interactomes.

Robust advances in interactome analysis demand comprehensive, non-redundant and consistently annotated data sets. By non-redundant, we mean that the accounting of evidence for every interaction should be faithful: each independent experimental support is counted exactly once, no more, no less. While many interactions are shared among public repositories, none of them contains the complete known interactome for any model organism. In addition, the annotations of the same experimental result by different repositories often disagree. This brings up the issue of which annotation to keep while consolidating evidences that are the same. The iRefIndex database, including interactions from most popular repositories with a standardized protein nomenclature, represents a significant advance in all aspects, especially in comprehensiveness. However, iRefIndex aims to maintain all information/annotation from original sources and requires users to perform additional processing to fully achieve the aforementioned goals. Another issue has to do with protein complexes. Some databases represent experimentally observed complexes as interactions with more than two participants, while others expand them into binary interactions using spoke or matrix model. To avoid untested interaction information buildup, it is preferable to replace the expanded protein complexes, either from spoke or matrix models, with a flat list of complex members. To address these issues and to achieve our goals, we have developed ppiTrim, a script that processes iRefIndex to produce non-redundant, consistently annotated data sets of physical interactions. Our script proceeds in three stages: mapping all interactants to gene identifiers and removing all undesired raw interactions, deflating potentially expanded complexes, and reconciling for each interaction the annotation labels among different source databases. As an illustration, we have processed the three largest organismal data sets: yeast, human and fruitfly. While ppiTrim can resolve most apparent conflicts between different labelings, we also discovered some unresolvable disagreements mostly resulting from different annotation policies among repositories. Database URL: http://www.ncbi.nlm.nih.gov/CBBresearch/Yu/downloads/ppiTrim.html
Approach to the Treatment-Experienced Patient

The management of treatment-experienced patients is complex and challenging. Fortunately, new agents continue to be developed that offer hope to those who have developed resistance to currently available agents. Knowing when, how, and in whom to use new agents is never easy and highlights the importance of expert care for HIV-infected patients. The management of treatment-experienced patients requires considerable expertise, especially now that patients with highly resistant virus can hope to achieve full virologic suppression.
Expanding Regional Airport Usage to Accommodate Increased Air Traffic Demand

*Small regional airports present an underutilized source of capacity in the national air transportation system. This study sought to determine whether a 50 percent increase in national operations could be achieved by limiting demand growth at large hub airports and instead growing traffic levels at the surrounding regional airports. This demand scenario for future air traffic in the United States was generated and used as input to a 24-hour simulation of the national airspace system. Results of the demand generation process and metrics predicting the simulation results are presented, in addition to the actual simulation results. The demand generation process showed that sufficient runway capacity exists at regional airports to offload a significant portion of traffic from hub airports. Predictive metrics forecast a large reduction of delays at most major airports when demand is shifted. The simulation results then show that offloading hub traffic can significantly reduce nationwide delays.
Superior Forecasts of the U.S. Unemployment Rate Using a Nonparametric Method

We use a nonlinear, nonparametric method to forecast unemployment rates. This method is an extension of the nearest-neighbor method but uses a higher-dimensional simplex approach. We compare these forecasts with several linear and nonlinear parametric methods based on the work of Montgomery et al. (1998) and Carruth et al. (1998). Our main result is that, due to the nonlinearity in the data-generating process, the nonparametric method outperforms many other well-known models, even when these models use more information. This result holds for forecasts based on quarterly and on monthly data.
FR II Quasars: Infrared Properties, Star Formation Rates, and Extended Ionized Gas

We present Spitzer Infrared Spectrograph spectra and Multiband Imaging Photometer for Spitzer photometry of 12 radio-loud QSOs with FR II morphologies at z ~ 0.3. Six of the sources are surrounded by luminous extended emission-line regions (EELRs), while the other six do not have such extended nebulae. The two subsamples are indistinguishable in their mid-infrared (MIR) spectra and overall IR spectral energy distributions (SEDs). For both subsamples, the MIR aromatic features are undetected in either individual sources or their stacked spectra, and the SEDs are consistent with pure quasar emission without significant star formation. The upper limits to the star formation rate (SFR) are sufficiently low that starburst-driven superwinds can be ruled out as a mechanism for producing the EELRs, which are instead likely the result of the ejection of most of the gas from the system by blast waves accompanying the launching of the radio jets. The FR II quasars deviate systematically from the correlation between host galaxy SFR and black hole accretion rate apparently followed by radio-quiet QSOs, implying little or no bulge growth coeval with the current intensive black hole growth. We also present a new Spitzer estimate of the SFR for the starburst in the host galaxy of the compact steep-spectrum radio quasar 3C 48.
Multipass plate heat exchangers -- Effectiveness-NTU results and guidelines for selecting pass arrangements

Plate heat exchangers are classified on the basis of number of passes on each side and the flow arrangement in each channel, taking into account the end plate effects. This results in four configurations each for the 1-1 (1 Pass-1 Pass), 2-1, 2-2, 3-3, 4-1, 4-2, and 4-4 arrangements, and six configurations for the 3-1 arrangement. These arrangements are analyzed using the Gauss-Seidel iterative finite difference method; the plate arrangement that yields the highest effectiveness in each pass configuration is identified. Comprehensive results are presented in tabular form for the temperature effectiveness P{sub 1} and log-mean temperature difference correction factor F as functions of the number of transfer units NTU{sub 1}, the heat capacity rate ratio R{sub 1}, and the total number of thermal plates. On the basis of these results, specific guidelines are outlined for the selection of appropriate plate heat exchanger configurations.
An Algorithm and Criteria for Compressor Characteristics Real Time Modeling and Approximation

Numerous problems are encountered in realizing an adequate real time model for an aircraft engine. The purpose of this article is to propose a systematic approach for modeling and approximating the characteristics of an engine or engine component parts, and to apply this approach to the Viper compressor (VC) characteristics. The proposed approach introduces a set of quantitative model-performance measures. Monitoring these measures makes it possible to take care of the multiple objectives of the model simultaneously and individually, and to attach a guarantee level to the model behavior. A set of (66) models are considered, from which the adequate VC model for real time (RT) simulation purposes is determined.Copyright © 1990 by ASME
Revisiting the Solution Structure of Ceric Ammonium Nitrate

Ceric ammonium nitrate (CAN) is a single-electron-transfer reagent with unparalleled utility in organic synthesis, and has emerged as a vital feedstock in diverse chemical industries. Most applications use CAN in solution where it is assigned a monomeric [Ce(IV) (NO3 )6 ](2-) structure; an assumption traced to half-century old studies. Using synchrotron X-rays and Raman spectroscopy we challenge this tradition, converging instead on an oxo-bridged dinuclear complex, even in strong nitric acid. Thus, one equivalent of CAN is recast as a two-electron-transfer reagent and a redox-activated superbase, raising questions regarding the origins of its reactivity with organic molecules and giving new fundamental insight into the stability of polynuclear complexes of tetravalent ions.
A Novel Method of Caffeine Synthesis from Uracil

An inexpensive and novel method of caffeine synthesis starting from uracil in six simple steps is described. Uracil 1 is first converted to I, 3-dimethyluracil 2, followed by nitration, reduction, and cyclization to theophylline and finally methylation of theophylline forms caffeine.
High temperature meson propagators with domain-wall quarks.

We study the chiral properties of domain-wall quarks at high temperatures on an ensemble of quenched configurations. Low lying eigenmodes of the Dirac operator are calculated and used to check the extent to which the Atiyah-Singer index theorem is obeyed on lattices with finite N{sub 5}. We calculate the connected and disconnected screening propagators for the lowest mass scalar and pseudoscalar mesons in the sectors of different topological charge and note that they behave as expected. Separating out the would-be zero eigenmodes enables us to accurately estimate the disconnected propagators with far less effort than would be needed otherwise.
Inflammation in Atherosclerosis

Experimental work has elucidated molecular and cellular pathways of inflammation that promote atherosclerosis. Unraveling the roles of cytokines as inflammatory messengers provided a mechanism whereby risk factors for atherosclerosis can alter arterial biology, and produce a systemic milieu that favors atherothrombotic events. The discovery of the immune basis of allograft arteriosclerosis demonstrated that inflammation per se can drive arterial hyperplasia, even in the absence of traditional risk factors. Inflammation regulates aspects of plaque biology that trigger the thrombotic complications of atherosclerosis. Translation of these discoveries to humans has enabled both novel mechanistic insights and practical clinical advances.
Depression Babies: Do Macroeconomic Experiences Affect Risk Taking?*

We investigate whether differences in individuals’ experiences of macro-economic shocks affect longterm risk attitudes, as is often suggested for the generation that experienced the Great Depression. Using data from the Survey of Consumer Finances from 1964-2004, we find that birth-cohorts that have experienced high stock market returns throughout their life report lower risk aversion, are more likely to be stock market participants, and, if they participate, invest a higher fraction of liquid wealth in stocks. We also find that cohorts that have experience high inflation are less likely to hold bonds. These results are estimated controlling for age, year effects, and a broad set of household characteristics. Our estimates indicate that stock market returns and inflation early in life affect risk-taking several decades later. However, more recent returns have a stronger effect, which fades away slowly as time progresses. Thus, the experience of risky asset payoffs over the course of an individuals’ life affects subsequent risk-taking. Our results explain, for example, the relatively low rates of stock market participation among young households in the early 1980s (following the disappointing stock market returns in the 1970s depression) and the relatively high participation rates of young investors in the late 1990s (following the boom years in the 1990s).
Infrared Echoes Reveal the Shock Breakout of the Cas A Supernova

Through the serendipitous discovery of infrared echoes around the Cas A supernova remnant, the Spitzer satellite has provided astronomers with a unique opportunity to study the properties of the echoing material and the history and nature of the outburst that generated these echoes. In retrospect, we find that the echoes are also clearly visible as infrared "hot spots" in IRAS images of the region. The spectra of the echoes are distinct from that of the dust in the general diffuse interstellar medium (ISM), revealing hot silicate grains that are either stochastically heated to temperatures in excess of ~150 K or radiating at an equilibrium temperature of this value. We show that the maximum luminosity that can be generated by the radioactive decay of 56Ni is not capable of producing such spectra, and could therefore not have given rise to the echoes. Instead, we find that the echoes must have been generated by an intense and short burst of EUV-UV radiation associated with the breakout of the shock through the surface of the exploding star. The inferred luminosity of the burst depends on the amount of attenuation in the intervening medium to the clouds, and we derive a burst luminosity of ~1.5 × 1011 L☉ for an assumed H-column density of 1.5 × 1019 cm−2. The average H-column density of the IR-emitting region in the echoing clouds is about 5 × 1017 cm−2. Derivation of their density requires knowledge of the width of the echo that is sweeping through the ISM, which in turn is determined by the duration of the burst. A burst time of ~1 day gives a cloud density of ~400 cm−3, typical of dense IR cirrus.
Near-Field Focusing Plates and Their Design

We describe the design of near-field focusing plates, which are grating-like structures that can focus electromagnetic radiation to spots or lines of arbitrarily small subwavelength dimension. A general procedure is outlined for designing a near-field plate to achieve a desired focus, and its implementation at microwave frequencies is discussed in detail. Full-wave (method of moments) simulations clearly demonstrate a passive near-field plate's ability to overcome the diffraction limit. Finally, it is shown that performance of the plates is weakly affected by losses..
Finiteness of classifying spaces of relative diffeomorphism groups of 3–manifolds

The main theorem shows that if M is an irreducible compact connected ori- entable 3{manifold with non-empty boundary, then the classifying space BDi (M rel @M) of the space of dieomorphisms of M which restrict to the identity map on @M has the homotopy type of a nite aspherical CW{complex. This answers, for this class of manifolds, a question posed by M Kontsevich. The main theorem follows from a more precise result, which asserts that for these manifolds the mapping class group H(M rel @M) is built up as a se- quence of extensions of free abelian groups and subgroups of nite index in relative mapping class groups of compact connected surfaces.
The phosphodiesterase 3 inhibitor ORG 9935 inhibits oocyte maturation during gonadotropin-stimulated ovarian cycles in rhesus macaques.

Abstract To determine whether phosphodiesterase (PDE) 3 inhibitors prevent the resumption of meiosis by primate oocytes in vivo, rhesus macaques were stimulated to develop multiple preovulatory follicles by administering human recombinant gonadotropins, and follicles were aspirated 34 h after an ovulatory stimulus (human chorionic gonadotropin [hCG]). Monkeys received no further treatment (controls) or the PDE3 inhibitor ORG 9935 (a) exclusively in the periovulatory interval beginning 6���12 h prior to receiving hCG at 200 mg/kg every 12 h orally (PER200) or a 200 mg/kg oral loading dose followed by 50 mg/kg sc every 6 h (PER50) or (b) throughout the ovarian stimulation protocol with daily increases until a dose of 200 mg/kg bid was administered onward from the eighth day of ovarian stimulation (EXT200). The primary outcome was the number of oocytes that had resumed meiosis (germinal vesicle breakdown [GVBD]) at collection. At initial aspiration, 85% of oocytes recovered from control animals ( n =4) had progressed to GVBD compared with 53% (p n =2), PER50 ( n =1) and EXT200 ( n =3) groups, respectively. Although spontaneous maturation of oocytes was observed during follow-up culture in the absence of ORG 9935, none of the oocytes in the PER50 or EXT200 underwent normal fertilization in vitro. These results demonstrate that the PDE3 inhibitor ORG 9935 blocks oocyte maturation during gonadotropin-stimulated ovarian cycles in rhesus macaques and suggest that PDE3 inhibitors have potential clinical use as contraceptives in women.
Topological Calculation of the Phase of the Determinant of a Non Self-Adjoint Elliptic Operator

We study the zeta-regularized determinant of a non self-adjoint elliptic operator on a closed odd-dimensional manifold. We show that, if the spectrum of the operator is symmetric with respect to the imaginary axis, then the determinant is real and its sign is determined by the parity of the number of the eigenvalues of the operator, which lie on the positive part of the imaginary axis. It follows that, for many geometrically defined operators, the phase of the determinant is a topological invariant. In numerous examples, coming from geometry and physics, we calculate the phase of the determinants in purely topological terms. Some of those examples were known in physical literature, but no mathematically rigorous proofs and no general theory were available until now.
The Best as Enemy of the Good The Port Authority’s 4th Jetport, Lindenthal’s Massive Span over the Hudson, and the George Washington Bridge

Students of complex organizations have often noted the tendency of organizational leaders to block out crucial information that raises doubts about plans and evidence they have already embraced. Re...
Claiming Authority: How Women Explain their Ascent to Top Business Leadership Positions

Abstract Career stories of 50 female executives from major corporations and high-growth entrepreneurial ventures suggest two alternative accounts of how women legitimize their claims to top leadership positions: navigating and pioneering. In navigating accounts, the women legitimized their claims to top authority positions by following well institutionalized paths of career advancement (e.g., high performance in line jobs) and self-advocating with the gatekeepers of the social hierarchy (e.g., bosses, investors). In pioneering accounts, the women articulated a strategic vision and cultivated a community of support and followership around their strategic ideas and leadership. The career stories suggested that, when the women's authority claims were not validated, they engaged in narrative identity work to revise their aspirations and legitimization strategies. Sometimes narrative identity work motivated women to shift from one type of account to another, particularly from navigating to pioneering. Based on inductive analyses of these 50 career stories, I propose a process model of how women legitimize their claims to top leadership positions by recursively resetting career accounts as authority claims succeed or fail.
Entry System Options for Human Return from the Moon and Mars

Earth entry system options for human return missions from the Moon and Mars were analyzed and compared to identify trends among the configurations and trajectory options and to facilitate informed decision making at the exploration architecture level. Entry system options included ballistic, lifting capsule, biconic, and lifting body configurations with direct entry and aerocapture trajectories. For each configuration and trajectory option, the thermal environment, deceleration environment, crossrange and downrange performance, and entry corridor were assessed. In addition, the feasibility of a common vehicle for lunar and Mars return was investigated. The results show that a low lift-to-drag ratio (L/D = 0.3) vehicle provides sufficient performance for both lunar and Mars return missions while providing the following benefits: excellent packaging efficiency, low structural and TPS mass fraction, ease of launch vehicle integration, and system elegance and simplicity. Numerous configuration options exist that achieve this L/D.
Inelastic impact of a sphere on a massive plane: Nonmonotonic velocity-dependence of the restitution coefficient

We have studied the coefficient of restitution, η, in normal collisions of a non-rotating sphere on a massive plate for a range of materials, impact velocity and sphere size. The measured coefficient of restitution does not monotonically vary with velocity. This effect is attributed to dynamics that occur during the finite duration of impact, since the time scales of the vibrational modes of the plate are comparable to the contact time. The measured effect is robust and is expected to be ubiquitous in fluidized granular media. We also find that η is a decreasing function of sphere radius, with a dependence that is not captured by existing models of impact.
Light-heavy-ion collisions: a window into pre-equilibrium QCD dynamics?

Relativistic collisions of light on heavy ions (p + Au at $$\sqrt{s}=7.7$$ GeV, p + Au , d + Au , $$^3$$ He + Au at $$\sqrt{s}=62.4$$ GeV and 200 GeV and p + Pb , $$^3$$ He + Pb at $$\sqrt{s}=5.02$$ TeV) are simulated using “superSONIC”, a model that includes pre-equilibrium flow, viscous hydrodynamics and a hadronic cascade afterburner. Even though these systems have strong gradients and only consist of at most a few tens of charged particles per unit rapidity, one finds evidence that a hydrodynamic description applies to these systems. Based on these simulations, the presence of a triangular flow component in d + Au collisions at $$\sqrt{s}=200$$ GeV is predicted to be similar in magnitude to that found in $$^3$$ He + Au collisions. Furthermore, the $$v_3(p_T)$$ ratio of $$^3$$ He + Au to d + Au is found to be sensitive to the presence of pre-equilibrium flow. This would imply an experimentally accessible window into pre-equilibrium QCD dynamics using light-heavy-ion collisions.
The influence of coupling on the free vibration of anisotropic thin-walled closed-section beams

Abstract A solution procedure for thin-walled laminated composite beams is presented. Two configurations are considered, producing extension-twist and bending-twist coupling, respectively. The influence of coupling on the characteristic equations for free vibration is isolated. It is shown that the characteristic determinant for extension-twist coupling can be expressed as the product of the two decoupled ones. For the case of bending-twist coupling, a simple-quasi-decoupled procedure is developed. This model is shown to provide accurate predictions for natural frequencies of practical interest for slender, laminated composite box beams.
Rotational barriers in alkanes

Rotational barriers in alkanes play a fundamental role in the stereochemistry and dynamics of alkanes and others such as proteins. Yet, the proper understanding of their origin which is central to chemical theory remains controversial. Currently, there are two major competing models to interpret the barriers, one is the steric repulsion model and the other is hyperconjugation model. No consensus has been reached. It is thus important to critically examine the quantum mechanical approaches producing conflicting data which lead to these models, as various approximations must be introduced to derive either the steric or hyperconjugative interaction energies in these approaches. The hyperconjugation model is largely based on the popular natural bond orbital (NBO) analysis which can estimate individual interactions between occupied bond orbitals and vicinal unoccupied antibond orbitals. But the concern is that these localized bond orbitals are projected out from a delocalized wavefunction and thus nonoptimal. Alternatively, recent studies with other methods notably the ab initio valence bond theory where localized orbitals are self-consistently optimized reinstate the conventional steric repulsion model, although the NBO method correctly predicts that there is stronger hyperconjugative interaction in staggered structures than in eclipsed structures. After all, it is the steric effect rather than the hyperconjugation effect that plays a dominating role in rotational barriers in alkanes. © 2011 John Wiley & Sons, Ltd. WIREs Comput Mol Sci 2011 1 164-171 DOI: 10.1002/wcms.22
Enantioselective synthesis of α-terpineol and nephthenol by intramolecular acyloxazolidinone enolate alkylations

Enolate anions generated from norterpenyl bromides bearing oxazolidinone chiral auxiliaries at the chain termini underwent efficient, stereo-biased cyclizations to form 6- and 14-membered rings in novel synthetic routes to α-terpineol and nephthenol enantiomers.
The relationship between rainfall and human density and its implications for future water stress in sub-Saharan Africa

Abstract This paper estimates the relationship between average rainfall and population density in Sub-Saharan Africa in order to assess the consequences of climate and demographic changes in terms of future water stress in that region. Geographic Information System (GIS) data on density and rainfall and climate change scenarios are combined in order to identify areas which will be subject to increased pressures stemming from excessive population, given their precipitation levels. We first describe the empirical relationship existing between average yearly rainfall and density over sub-Saharan Africa. The limit of 900 mm of annual rainfall appears to define the threshold below which water constitutes a binding constraint to higher densities. Above that threshold, density and rainfall are not spatially correlated. In a second stage, we identify areas subject to water stress. In our framework, those are defined as zones belonging to the right end of the distribution of densities conditional on average rainfall. In a last step, localized population projections and changes in rainfall predicted by two mainstream climate change scenarios are utilized to assess the respective impacts of those two factors on the changes in extent and distribution of high-stress zones over the continent between 2000 and 2050. If population growth follows projected trends, density increases across the continent should lead to a significant increase in the extent of such zones, especially around the Sahel belt and in Eastern Africa. The impact of changes in rainfall is more difficult to assess, because climate models differ locally as regards projections of yearly rainfall, especially in intermediate zones such as the Sahel. If, according to the predictions of most climate models, the Sahel were to experience average rainfall increases, these would ease, though not offset totally, the pressure stemming from demographic growth in that region. In contrast, in most of Eastern Africa, predicted drops in average rainfall would work in the same direction as demographic changes to increase the pressure on significant parts of the territory. In Southern Africa, demographic stagnation is likely to mitigate significantly the impact of climate change.
Magnetic design of trim excitations for the Advanced Light Source storage ring sextupole

The Advanced Light Source (ALS) storage ring sextupole is a unique multi-purpose magnet. It is designed to operate as a sextupole with three auxiliary trim modes: horizontal steering, vertical steering, and skew quadrupole. A perturbation theory for iron-dominated magnets developed by Klaus Halbach (1969) provides the basis for this design. The three trim excitations are produced by violating sextupole symmetry and are thus perturbations of the normal sextupole excitation. The magnet was designed such that all four modes are decoupled and can be excited independently. This paper discusses the use of Halbach's perturbation theory to design the trim functions and to evaluate the primary asymmetry in the sextupole mode, namely, a gap in the return yoke to accommodate the vacuum chamber.
A rooted net of life

Phylogenetic reconstruction using DNA and protein sequences has allowed the reconstruction of evolutionary histories encompassing all life. We present and discuss a means to incorporate much of this rich narrative into a single model that acknowledges the discrete evolutionary units that constitute the organism. Briefly, this Rooted Net of Life genome phylogeny is constructed around an initial, well resolved and rooted tree scaffold inferred from a supermatrix of combined ribosomal genes. Extant sampled ribosomes form the leaves of the tree scaffold. These leaves, but not necessarily the deeper parts of the scaffold, can be considered to represent a genome or pan-genome, and to be associated with members of other gene families within that sequenced (pan)genome. Unrooted phylogenies of gene families containing four or more members are reconstructed and superimposed over the scaffold. Initially, reticulations are formed where incongruities between topologies exist. Given sufficient evidence, edges may then be differentiated as those representing vertical lines of inheritance within lineages and those representing horizontal genetic transfers or endosymbioses between lineages.
A FACILE SYNTHESIS OF DIYNES

Abstract Terminal alkynes undergo self-coupling reactions in the presence of palladium bis(triphenyl phosphine) dichloride, copper(I) iodide iodine and diisopropyl amine to give the corresponding diynes in good yields.
Synthesis of N,N-bis(3-butenyl)amines from 2-azaallyl dication synthetic equivalents and conversion to 2,3,6,7-tetrahydroazepines by ring-closing metathesis.

N,N-Bis(3-butenyl)amines can be prepared by the double allylation of either (2-azaallyl)stannanes or (2-azaallyl)nitriles, both of which thereby act as synthetic equivalents to amine α,α‘-dications (2-azaallyl dications). Allylmagnesium bromide is the reagent of choice for the double allylation of both substrates, although allyllithium also effects the double allylation of (2-azaallyl)nitriles. Ring-closing metathesis can be performed on the N-protected amines, or with in situ protonation, on the free amines to provide 2,3,6,7-tetrahydroazepines. (2-Azaallyl)nitriles can also be monoallylated to provide N-(3-butenyl)aminonitriles, whereas the double allylation of (2-azaallyl)stannanes cannot be stopped at monoallylation. (2-Azaallyl)silanes undergo monoallylation to give N-(3-butenyl)aminosilanes but do not undergo double allylation.