cssi/SciSciGPT-SciSciNet huggingface dataset:
Application of Coherence Theory to Modeling of Blackbody Radiation at Close Range

We apply coherence-propagation theory to model the radiation generated by a planar passive thermal source of any state of coherence. Of our particular interest is the blackbody calibration source with partially coherent characteristic that produces the radiant intensity with its angular distribution following Lambert’s cosine law in the far field. A closed-form expression of the Poynting vector of the electromagnetic field is obtained from the theoretical framework. The formulation links the radiation field to the correlation function of the sources in a straightforward manner, though numerical computation of the Poynting vector involves evaluation of a quadruple integral and is difficult to implement directly, especially when the observation of radiation occurs at a close distance from the source. The study of the close-range radiation would, in particular, benefit the microwave remote sensing radiometric calibration that is encountered in terrestrial laboratories and space-borne satellites. To tackle the challenges in numerical calculation, we have made a few mathematical adjustments to develop a feasible scheme for improved computational efficiency, including reformulation in the angle-impact notation and various simplifications of the integration. We apply the theory and numerical techniques to simulate thermal radiation in some illustrative examples such as an isothermal blackbody source, a blackbody misaligned from the on-axis position, and a nonuniformly heated blackbody target. The coherence property of the blackbody source is shown to possess influential impacts on the radiation arising from such a source, especially in the near-field range where most measurements of the radiation take place in a practical system. The theory and technical approaches provide a systematic and reliable way to quantify the Poynting vector radiated by the blackbody source in a microwave remote-sensing radiometer.
CILogon: A federated X.509 certification authority for cyberinfrastructure logon

CILogon provides a federated X.509 certification authority for secure access to cyberinfrastructure such as the Extreme Science and Engineering Discovery Environment. CILogon relies on federated authentication Security Assertion Markup Language OASIS, Burlington, MA USA and OpenID for determining user identities when issuing certificates. Federated authentication enables users to obtain certificates using existing identities university, Google, etc.. Federated authentication also enables CILogon to serve a national-scale user community without requiring a large network of registration authorities performing manual user identification. CILogon supports multiple levels of assurance and custom interfaces for specific user communities. In this article, we introduce the CILogon service and describe experiences and lessons learned from the first 3years of operation. © 2014 The Authors. Concurrency and Computation: Practice and Experience published by John Wiley & Sons Ltd.
Affine feature extraction: A generalization of the Fukunaga-Koontz transformation

Dimension reduction methods are often applied in machine learning and data mining problems. Linear subspace methods are the commonly used ones, such as principal component analysis (PCA), Fisher's linear discriminant analysis (FDA), common spatial pattern (CSP), et al. In this paper, we describe a novel feature extraction method for binary classification problems. Instead of finding linear subspaces, our method finds lower-dimensional affine subspaces satisfying a generalization of the Fukunaga-Koontz transformation (FKT). The proposed method has a closed-form solution and thus can be solved very efficiently. Under normality assumption, our method can be seen as finding an optimal truncated spectrum of the Kullback-Leibler divergence. Also we show that FDA and CSP are special cases of our proposed method under normality assumption. Experiments on simulated data show that our method performs better than PCA and FDA on data that is distributed on two cylinders, even one within the other. We also show that, on several real data sets, our method provides statistically significant improvement on test set accuracy over FDA, CSP and FKT. Therefore the proposed method can be used as another preliminary data-exploring tool to help solve machine learning and data mining problems.
N-SITE: A DISTRIBUTED CONSENSUS BUILDING AND NEGOTIATION SUPPORT SYSTEM

This paper presents N-Site, a distributed consensus building and negotiation support system, which is used to provide geographically dispersed teams with agile access to a Web-based group decision support system. Four teams located in France, Mexico, the Ukraine, and the United States participated in the N-Site project. Each team was required to research the problem using the World Wide Web (WWW). With this background, each team identified opportunities, threats and alternatives as a basis for developing a response to the Cuban Missile Crisis that confronted President Kennedy in October 1962. The strategic assessment model (SAM) (M. Tavana, J. Multi-Criteria Decision Anal.11 (2002) 75–96; M. Tavana and S. Banerjee, Decision Sci.26 (1995) 119–143.) was used by each team to choose a strategy that best fit the team's perspective. SAM and WWW enabled the teams to evaluate strategic alternatives and build consensus based on a series of intuitive and analytical methods including environmental scanning, the anal...
Sensitivity of the transmission zeros of flexible space structures

The uncertainties inherent in the dynamics of flexible spacecraft make sensitivity and robustness questions very important when designing vibration isolation systems for these vehicles. One technique recently proposed for this problem is pole/zero cancellation, in which state feedback is used to make as many closed-loop modes as possible unobservable at the points on the structure where vibrations are to be minimized. Study of the robustness properties of this approach first requires an analysis of the sensitivity of the transmission zeros of second-order structural models. These questions are addressed in this paper, where it is proved (first in terms of partial derivatives and then condition numbers) that the sensitivities of the transmission zeros of any structure with collocated sensors and actuators are closely related to those of the poles of the system. Furthermore, the closed-loop poles produced by applying pole/zero cancellation to such a structure are shown to have sensitivities approaching those of the zeros, so these too are approximately given from the sensitivities of the open-loop poles. Finally, these points are illustrated by simple examples.
Entrepreneurship and innovation: public policy frameworks

The purpose of this paper is to identify and unravel the disparate views toward innovation prevalent within the economic community and to link them to the various public policy approaches. These various schools of thought, or ways of thinking about the economy in general and the role of entrepreneurship and innovation in particular, not only shape how innovation and entrepreneurial activity are valued, but also the overall policy debate concerning innovation and entrepreneurship. Unraveling of these views highlights the disparate way in which entrepreneurial activity leading to innovation is valued.
Nonspecific binding limits the number of proteins in a cell and shapes their interaction networks

Multicellular organisms, from Caenorhabditis elegans to humans, have roughly the same number of protein encoding genes. We show that the need to prevent disease-causing nonspecific interactions between proteins provides a simple physical reason why organism complexity is not reflected in the number of distinct proteins. By collective evolution of the amino acid sequences of protein binding interfaces we estimate the degree of misbinding as a function of the number of distinct proteins. Protein interaction energies are calculated with an empirical, residue-specific energy function tuned for protein binding. We show that the achievable energy gap favoring specific over nonspecific binding decreases with protein number in a power-law fashion. From the fraction of proteins involved in nonspecific complexes as a function of increasing protein number and decreasing energy gap, we predict the limits these binding requirements place on the number of different proteins that can function effectively in a given cellular compartment. Remarkably, the optimization of binding interfaces favors networks in which a few proteins have many partners, and most proteins have few partners, consistent with a scale-free network topology. We conclude that nonspecific binding adds to the evolutionary pressure to develop scale-free protein–protein interaction networks.
Composite Magnetostrictive Materials For Advanced Automotive Magnetomechanical Sensors

The need for non-contact torque sensors has sparked considerable interest in developing new magnetomechanical sensor materials [1, 2, 3, 4, 5]. Highly magnetostrictive materials, such as Terfenol (Tb0.3Dy0.7Fe2) [6], SmFe2 [7] and other rare-earth-iron compounds have been considered as candidates for such applications. These materials have very high saturation magnetostrictions (1000–3000ppm) [6], and might reasonably be expected to have high sensitivity of magnetization to stress and therefore be suitable for magnetomechanical sensor applications. Maraging steel has been considered an alternative sensor material by Garshelis [2]. Co-ferrite and metal-bonded Co-ferrite composites have recently been investigated by the authors as an alternative to existing materials competing for use in automotive and other torque sensing applications. The materials are inexpensive and non-corroding, and the metal-bonded Co-ferrite composites are mechanically robust and can be attached (e.g. by brazing) to metal parts. They show a steep slope of magnetostriction at low applied fields, (dλ/dH)σ, which contributes to a high sensitivity of magnetic induction to stress, hence giving high signal-to-background noise ratios in sensor applications.
Explicit Construction and Uniqueness for Universal Operator Algebras of Directed Graphs

Given a directed graph, there exists a universal operator algebra and universal C*-algebra associated to the directed graph. In this paper we give intrinsic constructions of these objects. We provide an explicit construction for the maximal C*-algebra of an operator algebra. We also discuss uniqueness of the universal algebras for finite graphs, showing that for finite graphs the graph is an isomorphism invariant for the universal operator algebra of a directed graph. We show that the underlying undirected graph is a Banach algebra isomorphism invariant for the universal C*-algebra of a directed graph.
Organometallic Chemistry sans Organometallic Reagents: Modulated Electron-Transfer Reactions of Subvalent Early Transition Metal Salts

The potential of low-valent, early transition-metal reagents as selective reductants in organic chemistry has been foreshadowed by intensive research on the ill-defined and heterogeneous subvalent titanium intermediates generated in the McMurry reaction and its numerous variants. As part of the long-term research effort to develop soluble, well-defined transition-metal reductants of modulated and selective activity toward organic substrates, the THF-soluble reductant, titanium dichloride, has been throughly examined, as well as the analogous ZrCl2 and HfCl2 reagents, all of which are readily obtainable by the alkylative reduction of the Group tetrachloride by butyllithium in THF. Noteworthy is that such interactions of MCl4 with butyllithium in hydrocarbon media lead, in contrast, to M(III) or M(IV) halide hydrides. Analogous alkylative reductions in THF applied to VCl4, CrCl3, and MoCl5 have yielded reducing agents similar to those obtained from Mcl4 but gradated in their reactivity. Such reductants have proved capable of coupling carbonyl derivatives, benzylic halides, acetylenes and certain olefins in a manner consistent with an oxidative addition involving a two-electron transfer (TET). Such a reaction pathway is consistent with the observed stereochemistry of pinacol formation from ketones and for the reductive dimerization of alkynes. In contrast of the reaction of CrCl3 with two equivalents of butyllithium, which leads to a CrCl intermediate, the interaction of CrCl3 in THF with four equivalents of butyllithium at –78°C yields a reagent of the empirical formulation, LiCrH4.2LiCl.2 THF, as supported by elemental and gasometric analysis of its protolysis. This hydridic reductant cleaves a wide gamut of s carbon–heteroatom bonds (C–X, C–O, C–S and C–N), towards which the CrCl reductant is unreactive. The type of cleavage and/or coupled products resulting from the action of “LiCrH4” on these substrates in best understood as arising from single-electron transfer (SET). In light of the aforementioned findings, the gradated reducing action noted among TiCl2, HfCl2 and CrCl, as well as the contrasting reducing behavior between CrCl and LiCrH4, there is no doubt that future research with early transition metals will continue to yield novel reductants of modulated and site-selective reactivity.
Metrics for Assessing Design Freedom and Information Certainty in the Early Stages of Design

Our primary focus in this paper is on open engineering systems which are readily adaptable to changing design requirements. Designing an open engineering system allows a family of products to be developed around a common baseline model. This entails increasing design freedom and design knowledge during the early stages of design. Toward this end, developing ranged sets (as opposed to points sets) of top-level design specifications provides a means to improve system flexibility by increasing design knowledge while maintaining design freedom. Consequently, our secondary focus in this paper is on metrics for assessing the design freedom and information certainty associated with a ranged set of top-level design specifications. As a demonstration, these metrics are applied to an example problem, namely, the conceptual design of a family of aircraft. Our emphasis in this paper is on introducing open engineering systems and metrics for design freedom and information certainty, not on our example, per se.
Auditor's Reputation and Equity Offerings: The Case of Arthur Andersen

The certifying and monitoring role of auditors is valuable to clients. By examining the impact of Arthur Andersen's worsening reputation on its clients, we find a 200 basis point more negative reaction to seasoned equity offering (SEO) announcements for firms audited by Andersen. The median firm in our sample loses 31.4 million more than a non-Andersen client. We do not find any unusual underpricing for these SEOs, which suggests that any accounting concerns about the issuers are resolved before the issue dates.
Squaring down of general MIMO systems to invertible uniform rank systems via pre-and/or post-compensators

Abstract Pre- and/or post-compensators are designed to square down a general MIMO system to a uniform rank system, the structure of which is almost similar to a SISO system. The method of squaring down either does not change the finite zero structure of the given MIMO system or simply adds additional finite zeros in the left half s-plane. The significance of such a squaring down lies in the simplicity of the structure of a uniform rank system lending itself for easy analysis and control design.
Anti‐infective therapy at end of life: Ethical decision‐making in hospice‐eligible patients

Clear guidelines addressing the ethically appropriate use of anti-infectives in the setting of hospice care do not exist. There is lack of understanding about key treatment decisions related to infection treatment for patients who are eligible for hospice care. Ethical concerns about anti-infective use at the end of life include: (1) delaying transition to hospice, (2) prolonging a dying process, (3) prescribing regimens incongruent with a short life expectancy and goals of care, (4) increasing the reservoir of potential resistant pathogens, (5) placing unreasonable costs on a capitated hospice system. Although anti-infectives are thought to be relatively safe, they can place a burden on patients and be inconsistent to particular care plans. The current complex, and at times fragmented, medical care often fails to address these issues in decision-making. In many ways, the ethics governing the end of life decisions related to dialysis, hydration/nutrition, and hypercalcemia parallel those of anti-infectives. In this article we articulate important elements in ethical decision-making in the application of anti-infectives for patients who are eligible for hospice care, and we point to the need for prospective studies to help refine particular guidelines in these cases.
Practice-Based Versus Telemedicine-Based Collaborative Care for Depression in Rural Federally Qualified Health Centers: A Pragmatic Randomized Comparative Effectiveness Trial

Using telemedicine technologies, off-site mental health specialists collaborating with on-site primary care physicians yielded better depression outcomes than practice-based care with staff available on-site. In this study of mostly rural, unemployed, and uninsured patients with treatment-resistant depression and numerous comorbidities, those patients assigned to a telemedicine-based group had significantly and substantially greater treatment response rates, remission rates, reductions in depression severity, and increases in mental health status and quality of life than patients assigned to the practice-based care group.
Paleontology and The Geological Society of America: The first 100 years

Since its early years of publication, the GSA Bulletin has been an outlet for paleontologists who want their results to reach a broad scientific audience. During the first 40 years, paleontologic papers featured a wide variety of subjects, including systematics, biostratigraphy, correlation, and paleogeography. After the Journal of Paleontology and other specialized journals began publication, applied paleontology characterized many of the Bulletin articles. From about 1930 to 1960, a series of correlation papers on the Phanerozoic systems dominated the Bulletin . Systematic studies were generally published as Special Papers or Memoirs , starting in the 1930s. Beginning in the 1950s and continuing to the present, the GSA and the University of Kansas Press have produced 36 volumes of the Treatise on Invertebrate Paleontology , arguably the most significant paleontologic enterprise of the century. In the past 20 years, the Bulletin has contained many papers in which paleontology was applied to solving general geologic and biologic problems. Doubtless, this trend will continue, in both the Bulletin and in Geology , for many years to come.
THE CLOSE BINARY FRACTION OF DWARF M STARS

We describe a search for close spectroscopic dwarf M star binaries using data from the Sloan Digital Sky Survey to address the question of the rate of occurrence of multiplicity in M dwarfs. We use a template-fitting technique to measure radial velocities from 145,888 individual spectra obtained for a magnitude-limited sample of 39,543 M dwarfs. Typically, the three or four spectra observed for each star are separated in time by less than four hours, but for ~17% of the stars, the individual observations span more than two days. In these cases we are sensitive to large-amplitude radial velocity variations on timescales comparable to the separation between the observations. We use a control sample of objects having observations taken within a four-hour period to make an empirical estimate of the underlying radial velocity error distribution and simulate our detection efficiency for a wide range of binary star systems. We find the frequency of binaries among the dwarf M stars with a < 0.4 AU to be 3%-4%. Comparison with other samples of binary stars demonstrates that the close binary fraction, like the total binary fraction, is an increasing function of primary mass.
Bomb or Boon: Linking Population, People and Power in Fragile Regions; Comment on “The Pill Is Mightier Than the Sword”

The relationship between population structure and violent conflict is complex and heavily dependent on the behavior of other variables like governance, economic prospects, and urbanization. While addressing rapid population growth might be a necessary condition for peace, it is by no means sufficient. Concomitant steps must also be taken to foster inclusivity, guarantee broader rights for all, particularly women, rebuild social contracts and ensure that all citizens have equal access to economic opportunity. Measures to control family size could reduce dependency and create greater socio-economic opportunities for women and youth, By so doing, the "youth bulge" phenomenon could be a boon for rapidly growing developing countries.
Efficient reordering of Prolog programs

Prolog programs are often inefficient: execution corresponds to a depth-first traversal of an AND/OR graph; traversing subgraphs in another order can be less expensive. It is shown how the reordering of clauses within Prolog predicates, and especially of goals within clauses, can prevent unnecessary search. The characterization and detection of restrictions on reordering is discussed. A system of calling modes for Prolog, geared to reordering, is proposed, and ways to infer them automatically are discussed. The information needed for safe reordering is summarized, and which types can be inferred automatically and which must be provided by the user are considered. An improved method for determining a good order for the goals of Prolog clauses is presented and used as the basis for a reordering system. >
Contingent Valuation: A User's Guide†

Contingent valuation (CV) is a survey-based method frequently used for placing monetary values on environmental goods and services not bought and sold in the marketplace. CV is usually the only feasible method for including passive-use considerations in an economic analysis, a practice that has engendered considerable controversy. The issue of what a CV study tries to value is first addressed from the perspective of a policy-maker, and then the controversy over the inclusion of passive-use is taken up in more detail. The major issues and positions taken in the technical debate over the use of CV are summarized from a user's perspective. Key design and implementation issues involved in undertaking a CV survey are examined, and the reader is provided with a set of factors to examine in assessing the quality of a CV study.
Evaluating Mean Magnetic Field in Flare Loops

We analyze multiple-wavelength observations of a two-ribbon flare exhibiting apparent expansion motion of the flare ribbons in the lower atmosphere and rising motion of X-ray emission at the top of newly-formed flare loops. We evaluate magnetic reconnection rate in terms of V r B r by measuring the ribbon-expansion velocity (V r) and the chromospheric magnetic field (B r) swept by the ribbons. We also measure the velocity (V t) of the apparent rising motion of the loop-top X-ray source, and estimate the mean magnetic field (B t) at the top of newly-formed flare loops using the relation 〈V t B t〉≈〈V r B r〉, namely, conservation of reconnection flux along flare loops. For this flare, B t is found to be 120 and 60 G, respectively, during two emission peaks five minutes apart in the impulsive phase. An estimate of the magnetic field in flare loops is also achieved by analyzing the microwave and hard X-ray spectral observations, yielding B=250 and 120 G at the two emission peaks, respectively. The measured B from the microwave spectrum is an appropriately-weighted value of magnetic field from the loop top to the loop leg. Therefore, the two methods to evaluate coronal magnetic field in flaring loops produce fully-consistent results in this event.
A Cyclopropane Fragmentation Approach to Heterocycle Assembly: A Convergent Synthesis of Oxepanes

A cyclopropanol fragmentation approach to the synthesis of oxepanes has been developed. This convergent strategy condenses cyclopropyl diols with aldehydes to form an acetal, which is subsequently rearranged to furnish a keto-oxepane. The reaction has been developed as a one-pot procedure, utilizing sequential addition of Al(OTf)3 and TiCl4. Yields range from 50 to 70% for the sequence. A Zimmerman−Traxler transition state disposing substituents in equatorial positions is consistent with the observed formation of strictly cis products.
Supercritical fluids as solvents for chemical and materials processing

Fluids near their critical point have dissolving power comparable to that of liquids, are much more compressible than dilute gases, and have transport properties intermediate between gas-and liquid-like. This unusual combination of physical properties can be advantageously exploited in environmentally benign separation and reaction processes, as well as for new kinds of materials processing.
BioDrugScreen: a computational drug design resource for ranking molecules docked to the human proteome

BioDrugScreen is a resource for ranking molecules docked against a large number of targets in the human proteome. Nearly 1600 molecules from the freely available NCI diversity set were docked onto 1926 cavities identified on 1589 human targets resulting in >3 million receptor–ligand complexes requiring >200 000 cpu-hours on the TeraGrid. The targets in BioDrugScreen originated from Human Cancer Protein Interaction Network, which we have updated, as well as the Human Druggable Proteome, which we have created for the purpose of this effort. This makes the BioDrugScreen resource highly valuable in drug discovery. The receptor–ligand complexes within the database can be ranked using standard and well-established scoring functions like AutoDock, DockScore, ChemScore, X-Score, GoldScore, DFIRE and PMF. In addition, we have scored the complexes with more intensive GBSA and PBSA approaches requiring an additional 120 000 cpu-hours on the TeraGrid. We constructed a simple interface to enable users to view top-ranking molecules and access purchasing and other information for further experimental exploration.
On programming a highly parallel machine to be an intelligent technician

This paper speculates on how to program a machine that is suitable for microelectronic components to be an intelligent technician. The point of departure is from a class of machines described by J. H. Holland in a concurrent paper entitled, "On Iterative Circuit Computers Constructed of Microelectronic Components and Systems." These machines consist of a regular lattice of active modules, each possessing both processing and memory functions. The goal is a machine with the problem solving capabilities of a smart human technical assistant, and the volume processing capabilities normally associated with digital computers. This goal is chosen because it coincides with many current developments. After discussing the eventual capabilities desired and the most striking features of Holland's machines, the speculation proceeds by considering the basic organization for information processing. This is followed by briefer treatments of the organization for problem solving, supervision, interpretation and production.
Harnessing Quinone Methides: Total Synthesis of (±)‐Vaticanol A

Although quinone methides are often postulated as intermediates in the biosynthesis of many polyphenolic natural products, deploying their power in a laboratory setting to achieve similar bond constructions has sometimes proven challenging. Herein, a total synthesis of the resveratrol trimer vaticanol A has been achieved through three instances of quinone methide chemistry. These operations, one of which succeeded only under very specific conditions, expediently generated its [7,5]-carbocyclic core, afforded a unique sequence for dihydrobenzofuran formation, and concurrently generated, in addition to the target molecule, a series of diastereomers reflective of many other isolates.
Sampling and Representation Complexity of Revenue Maximization

We consider (approximate) revenue maximization in mechanisms where the distribution on input valuations is given via “black box” access to samples from the distribution. We analyze the following model: a single agent, m outcomes, and valuations represented as m-dimensional vectors indexed by the outcomes and drawn from an arbitrary distribution presented as a black box. We observe that the number of samples required – the sample complexity – is tightly related to the representation complexity of an approximately revenue-maximizing auction. Our main results are upper bounds and an exponential lower bound on these complexities. We also observe that the computational task of “learning” a good mechanism from a sample is nontrivial, requiring careful use of regularization in order to avoid over-fitting the mechanism to the sample. We establish preliminary positive and negative results pertaining to the computational complexity of learning a good mechanism for the original distribution by operating on a sample from said distribution.
Ba11Cd8Bi14: bismuth zigzag chains in a ternary alkaline-earth transition-metal Zintl phase.

A new transition-metal-containing Zintl phase, Ba11Cd8Bi14, has been synthesized by a Cd-flux reaction, and its structure has been determined by a single-crystal X-ray diffraction. Ba11Cd8Bi14 crys...
Programmed elimination of cells by caspase-independent cell extrusion in C. elegans

The elimination of unnecessary or defective cells from metazoans occurs during normal development and tissue homeostasis, as well as in response to infection or cellular damage. Although many cells are removed through caspase-mediated apoptosis followed by phagocytosis by engulfing cells, other mechanisms of cell elimination occur, including the extrusion of cells from epithelia through a poorly understood, possibly caspase-independent, process. Here we identify a mechanism of cell extrusion that is caspase independent and that can eliminate a subset of the Caenorhabditis elegans cells programmed to die during embryonic development. In wild-type animals, these cells die soon after their generation through caspase-mediated apoptosis. However, in mutants lacking all four C. elegans caspase genes, these cells are eliminated by being extruded from the developing embryo into the extra-embryonic space of the egg. The shed cells show apoptosis-like cytological and morphological characteristics, indicating that apoptosis can occur in the absence of caspases in C. elegans. We describe a kinase pathway required for cell extrusion involving PAR-4, STRD-1 and MOP-25.1/-25.2, the C. elegans homologues of the mammalian tumour-suppressor kinase LKB1 and its binding partners STRADα and MO25α. The AMPK-related kinase PIG-1, a possible target of the PAR-4–STRD-1–MOP-25 kinase complex, is also required for cell shedding. PIG-1 promotes shed-cell detachment by preventing the cell-surface expression of cell-adhesion molecules. Our findings reveal a mechanism for apoptotic cell elimination that is fundamentally distinct from that of canonical programmed cell death.
High-Contrast Observations in Optical and Infrared Astronomy

High-contrast observations in optical and infrared astronomy are defined as any observation requiring a technique to reveal a celestial object of interest that is in such close angular proximity to another source brighter by a factor of at least 10 5 that optical effects hinder or prevent the collection of photons directly from the target of observation. This is a relatively new type of observation that enables research on previously obscured parts of the Universe. In particular, it is most applicable to comparative planetary science, a field that directly attacks such questions as “how common are planetary systems? What types of planets exist, and are there planets other than Earth that are capable of supporting life as we know it?” We survey the scientific motivations for high-contrast observations, provide an overview of the techniques currently being used or developed, and discuss some ideas and studies for future prospects.
Matrix embedding for large payloads

Matrix embedding is a previously introduced coding method that is used in steganography to improve the embedding efficiency (increase the number of bits embedded per embedding change). Higher embedding efficiency translates into better steganographic security. This gain is more important for long messages than for shorter ones because longer messages are, in general, easier to detect. In this paper, we present two new approaches to matrix embedding for large payloads suitable for practical steganographic schemes-one based on a family of codes constructed from simplex codes and the second one based on random linear codes of small dimension. The embedding efficiency of the proposed methods is evaluated with respect to theoretically achievable bounds
The Role of Personal Attributes in African American Roll-Call Voting Behavior in Congress

In this research note, the authors explore the extent to which personal attributes influence voting behavior for African American members of Congress. The authors test the relationship between legislators’ personal attributes and Poole and Rosenthal’s DW-NOMINATE scores for black members of the 101st to 108th Congresses. The results suggest that personal attributes matter. They increase the explained variance in the models, and factors such as generational cohort, religion, and military experience are statistically significant. These results suggest that while descriptive members of Congress share much in common, they should not be interpreted as monolithic with respect to congressional voting.
NEAR-INFRARED AND X-RAY OBSERVATIONS OF THE ENIGMATIC G70.7 1.2

We present high-resolution imaging of the puzzling radio and optical nebula G70.7+1.2 with the Keck Observatory's laser guide star adaptive optics (LGS-AO) system and the Chandra X-Ray Observatory. The archival X-ray observations show a hard (Γ ≈ 1.8), low-luminosity (L_X ≈ 4 × 10^(31) ergs s^(-1)) point source at the center of the nebula. Follow-up LGS-AO near-infrared imaging of the Chandra error circle reveals a relatively bright (K' ≈ 14 mag) counterpart. Both its color and brightness are consistent with a heavily obscured B star or possibly a late G/early K giant. The most plausible explanation is that this newly discovered X-ray source is a nonaccreting B star/pulsar binary powering the radio and optical nebula. If so, the luminous Be star discussed in the literature seemingly embedded in the nebula is not the dominant force responsible for shaping G70.7+1.2. Thus, we suggest that G70.7+1.2 is the result of two unrelated objects (a B star X-ray binary and a Be star) interacting with a dense molecular cloud. With this explanation we believe we have solved the mystery of the origin of G70.7+1.2.
A unified low elevation angle scintillation model

Enabling communications at very low elevation can lengthen the pass duration between a satellite and a ground station, which in turn can increase the amount of data return and possibly reduce the number of required supporting ground stations. Link performance, especially at very low angles and high frequencies, depends heavily on terrain, atmosphere, and weather, etc. Among the different crucial attenuations, scintillation fading plays a significant role and can greatly impair the performance of the link. It is therefore necessary to model correctly the overall impacts to the link due to scintillation fading. The current International Telecommunication Union Recommendation ITU-R P.618-10 describes three scintillation loss models depending on the elevation angles and percentage of time for which the loss exceeds certain threshold. Implementation of the recommendation resulted in many issues. Particularly, it was identified that (i) iterative solutions to an implicit nonlinear exponential model cannot be found in some cases, (ii) there is a discontinuity in fading values, (iii) scintillations at lower elevation angles from a model are unrealistically lower, (iv) for elevation angle between four and five degrees, there are two applicable scintillation models which yield conflicting values. In this article, we develop a new approach to unify the different fading models within the current ITU recommendation and remove the discrepancies completely. We further validated our models using the ITU-adopted scintillation data measured at Goonhilly, Great Britain and several recent NASA's Space Shuttle launches. This improved model has been provisionally approved in the ITU International Meeting in Italy, November 2010, and is being evaluated by the ITU members for adoption into the next version ITU Recommendation ITU-R P.618-10.
Optimal information retrieval from complex low frequency backgrounds in medical images

The application of image processing techniques to digital/filmless radiographs is studied. Planar X-ray images are generated using high-resolution photostimulable phosphor plate technology. The images' information content is optimized by repeated application of morphological closing and opening operations followed by a convolution and a subtraction. A broad variety of medical images are improved by offline, interactive application of similar processing methods. Criteria that may form the basis for image processing decisions such as structuring element size and the suitability of probability quantization are suggested. >
Reactive trajectories and the transition path process

We study the trajectories of a solution \(X_t\) to an Ito stochastic differential equation in \({\mathbb { R}}^d\), as the process passes between two disjoint open sets, \(A\) and \(B\). These segments of the trajectory are called transition paths or reactive trajectories, and they are of interest in the study of chemical reactions and thermally activated processes. In that context, the sets \(A\) and \(B\) represent reactant and product states. Our main results describe the probability law of these transition paths in terms of a transition path process \(Y_t\), which is a strong solution to an auxiliary SDE having a singular drift term. We also show that statistics of the transition path process may be recovered by empirical sampling of the original process \(X_t\). As an application of these ideas, we prove various representation formulas for statistics of the transition paths. We also identify the density and current of transition paths. Our results fit into the framework of the transition path theory by Weinan and Vanden-Eijnden.
Migrant Remittances and Exchange Rate Regimes in the Developing World

This article argues that the international financial consequences of immigration exert a strong influence on the choice of exchange rate regimes in the developing world. Over the past two decades, migrant remittances have emerged as a significant source of external finance for developing countries, often exceeding conventional sources of capital such as foreign direct investment and bank lending. Remittances are unlike nearly all other capital flows in that they are stable and move countercyclically relative to the recipient country’s economy. As a result, they mitigate the costs of forgone domestic monetary policy autonomy and also serve as the “risk-sharing” mechanism required by standard political economy models of currency unions. The observable implication of these arguments is that remittances increase the likelihood that policymakers adopt fixed exchange rates. An analysis of data on de facto exchange rate regimes and a newly available dataset on remittances for up to 74 developing countries from 1983 to 2004 provides strong support for these arguments; the results are robust to instrumental variable analysis and the inclusion of multiple economic and political control variables.
Discovery of Two T Dwarf Companions with the Spitzer Space Telescope

We report the discovery of T dwarf companions to the nearby stars HN Peg (G0 V, 18.4 pc, τ ~ 0.3 Gyr) and HD 3651 (K0 V, 11.1 pc, τ ~ 7 Gyr). During an ongoing survey of 5' × 5' fields surrounding stars in the solar neighborhood with the Infrared Array Camera aboard the Spitzer Space Telescope, we identified these companions as candidate T dwarfs based on their mid-infrared colors. Using near-infrared spectra obtained with SpeX at the NASA Infrared Telescope Facility, we confirm the presence of methane absorption that characterizes T dwarfs and measure spectral types of T2.5 ± 0.5 and T7.5 ± 0.5 for HN Peg B and HD 3651B, respectively. By comparing our Spitzer data to images from the Two Micron All Sky Survey obtained several years earlier, we find that the proper motions of HN Peg B and HD 3651B are consistent with those of the primaries, confirming their companionship. A comparison of their luminosities to the values predicted by theoretical evolutionary models implies masses of 0.021 ± 0.009 and 0.051 ± 0.014 M_⊙ for HN Peg B and HD 3651B, respectively. In addition, the models imply an effective temperature for HN Peg B that is significantly lower than the values derived for other T dwarfs at similar spectral types, which is the same behavior reported by Metchev & Hillenbrand for the young late L dwarf HD 203030B. Thus, the temperature of the L/T transition appears to depend on surface gravity. Meanwhile, HD 3651B is the first substellar companion directly imaged around a star that is known to harbor a close-in planet from radial velocity surveys. The discovery of this companion supports the notion that the high eccentricities of close-in planets like that near HD 3651 may be the result of perturbations by low-mass companions at wide separations.
A convenient synthesis of 5′-amino-5′-deoxythymidine and preparation of peptide-DNA hybrids

Abstract 5′-Amino-5′-deoxythymidine was prepared from thymidine in two steps and converted to its known 5′-methoxytrityl-protected 3′-phosphoramidite building block for DNA assembly on solid supports. Using this building block, peptide-DNA hybrids were synthesized in stepwise manner or via fragment condensation, both as single compounds and as small combinatorial libraries.
Why has CEO Pay Increased So Much

This paper develops a simple equilibrium model of CEO pay. CEOs have different talents and are matched to firms in a competitive assignment model. In market equilibrium, a CEO’s pay changes one for one with aggregate firm size, while changing much less with the size of his own firm. The model determines the level of CEO pay across firms and over time, offering a benchmark for calibratable corporate finance. The sixfold increase of CEO pay between 1980 and 2003 can be fully attributed to the six-fold increase in market capitalization of large US companies during that period. We find a very small dispersion in CEO talent, which nonetheless justifies large pay differences. The data broadly support the model. The size of large fi rms explains many of the patterns in CEO pay, across firms, over time, and between countries. (JEL D2, D3, G34, J3)
Shape-controlled metal nanocrystals for catalytic applications

The implication of shape control in nanocrystal synthesis goes far beyond aesthetic appeal. For metal nanocrystals, the shape not only determines their physicochemical properties but also their technological relevance for catalytic, plasmonic, photonic, and electronic applications. In particular, heterogeneous catalysis is a field that can benefit tremendously from the availability of metal nanocrystals with well-controlled shapes, which may serve to significantly increase reaction efficiency while decreasing material cost. This article provides a brief overview of our recent progress in generating shape-controlled nanocrystals with enhanced catalytic activity toward oxygen reduction and formic acid oxidation, two reactions that are crucial for the successful commercialization of fuel cell technology. The impact on other industrially important reactions will be discussed as well. We hope that this article provides a roadmap for further development of metal nanocrystal-based catalysts with enhanced performance through shape-controlled synthesis.
Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas

Recent experiments using proton backlighting of laser-foil interactions provide unique opportunities for studying magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph images indicate that the outer structure of a magnetic field entrained in a hemispherical plasma bubble becomes distinctly asymmetric after the laser turns off. It is shown that this asymmetry is a consequence of pressure-driven, resistive magnetohydrodynamic MHD interchange instabilities. In contrast to the predictions made by ideal MHD theory, the increasing plasma resistivity after laser turn-off allows for greater low-mode destabilization m 1 from reduced stabilization by field-line bending. For laser-generated plasmas presented herein, a mode-number cutoff for stabilization of perturbations with m81 +Dmk 2 max 1/2 is found in the linear growth regime. The growth is measured and is found to be in reasonable
Cellular Basis of Mechanotransduction

Physical forces, such as those due to gravity are fundamental regulators of tissue development. To influence morphogenesis, mechanical forces must alter growth and function. Yet little is known about how cells convert mechanical signals into a chemical response. This presentation attempts to place the potential molecular mediators of mechanotransduction within the context of the structural complexity of living cells.
Attorney empowerment in Voir Dire and the racial composition of juries

Giving attorneys more power in the voir dire (jury selection) process may allow them to 1) find grounds for dismissal of jurors whom they wish to strike on a priori grounds; 2) acquire information that enables them to identify favorably-inclined jurors more precisely; or both. Attorneys who are more skilled can better use such increased power to retain the jurors they prefer. We show theoretically that, because defense attorneys prefer non-white jurors a priori, the interaction of empowerment and defense attorney skill should produce juries with a greater proportion of non-whites if only the first mechanism is operative, but need not have this effect if the second is operative. We then examine these issues using a detailed dataset on all non-capital felony trials in four large and diverse counties over a two-year period. We find that skilled and empowered attorneys can indeed stack juries by retaining jurors predisposed to their side at a greater rate, and that the distribution of relative attorney skill in our data is such that defendants benefit on average. However, we find that empowerment has a small and insignificant impact on the racial composition of the seated jury, regardless of attorney skill.
Stability of queueing networks and scheduling policies

We develop a programmatic procedure for establishing the stability of queueing networks and scheduling policies. The method uses linear or nonlinear programming to determine what is an appropriate quadratic functional to use as a Lyapunov function. If the underlying system is Markovian, our method establishes not only positive recurrence and the existence of a steady-state probability distribution, but also the geometric convergence of an exponential moment. We illustrate this method on several example problems. >