cssi/SciSciGPT-SciSciNet huggingface dataset:
One-component surface waves in materials with symmetry

Abstract It has recently been established that the existence of one-component surface waves is compatible with material symmetry and that they can occur even in transversely isotropic materials. This paper deals primarily with the existence of one-component surface waves in materials with a plane of symmetry normal to the direction of propagation, with particular attention given to transversely isotropic materials in this class. Numerical results indicate that there are stable transversely isotropic materials for which one-component surface waves exist for any orientation of the symmetry axis relative to the free surface. A separate numerical search shows that the one-component surface wave is incompatible with cubic symmetry.
Adherence to Cardiovascular Disease Medications: Does Patient-Provider Race/Ethnicity and Language Concordance Matter?

Background Patient–physician race/ethnicity and language concordance may improve medication adherence and reduce disparities in cardiovascular disease (CVD) by fostering trust and improved patient–physician communication.
The secular acceleration of the Earth's spin

Summary. The power spectrum of the Earth's spin has important components with periods ranging from a few days to at least a few thousand years, and probably to the age of the Earth. The secular acceleration, as the term is used here, refers to the components with periods longer than three centuries. In the year 600, the secular acceleration was —19.9 ± 0.8 parts in 109 per century, while the value at the present time is less than half this size. The spin acceleration has important contributions from tidal friction and from an effect that is proportional to the square of the magnetic dipole moment. When these contributions are subtracted from the observed acceleration, we are left with a contribution that amounts to +41 parts in 109 per century. This amount probably results from an unknown combination of changes in the size of the core, in the amount of glaciation, and in the size of the gravitational constant.
Highly enantioselective Diels-Alder reactions of maleimides catalyzed by activated chiral oxazaborolidines.

Diels−Alder reactions of various combinations of maleimides and 1,3-dienes with cationic oxazaborolidines as catalysts have been shown to be highly efficient and enantioselective.
Novel imidazolination reaction of alkenes provides an easy access to new α,β-differentiated 1,2-vicinal diamines

α,β-Differentiated 1,2-vicinal diamines have been efficiently synthesized by using new electrophilic imidazolination reaction of alkenes. The hydrolysis of imidazolines was performed by treatment with 6 M HCl in THF at 70 °C without epimerization. Eight examples were examined to give good to excellent yields (87–96%).
SIM configuration evolution

The Space Interferometry Mission (SIM) is a space-based 10 m baseline Michelson interferometer. Planned for launch in 2005 aboard a Delta III launch vehicle, or equivalent, its primary objective is to measure the positions of stars and other celestial objects with an unprecedented accuracy of 4 micro arc seconds. The configuration of the space flight system to meet the very challenging requirements imposed by such an instrument has evolved considerably. This paper will discuss the evolution of the configuration and discuss some of the factors that have driven the overall configuration. SIM has undergone several transformations since the start of Phase A. During this phase of a project, it is desirable to perform system level trade studies, so the substantial evolution of the design that has occurred is quite appropriate. Part of the trade-off process has addressed two major underlying architectures: SIM Classic; and Son of SIM. The difference between these two architectures is related to the overall arrangement of the optical elements and the associated metrology system. Several different configurations have been developed for each architecture. Some of the more important aspects will be discussed. SIM has some extremely challenging goals: millikelvin thermal stability, nanometer stabilization of optics, picometer measurement of wavefront, and others. The projected viability of some of these areas has influenced design choices during the evolution of the many configurations that have been developed. For instance, the perceived complexity of the IR laser metrology system used to measure and control the positions of key optical elements was the strongest discriminator between the two architectures, and led to a decision to select SOS rather than Classic. More recently, an appreciation of the sensitivity to beam-walk within the SOS architecture is forcing a reconsideration of that decision. There is some hope that a full aperture metrology system may alleviate this issue.
Supply Analysis for Corn in the United States: The Impact of Changing Government Programs

Acreage supply relationships for corn in the United States are analyzed for 1948–70. Emphasis is on the effect of changes in government policies because similar programs for acreage control and price support are the most likely form of future policies. A model for empirical evaluation of loan rates, support and diversion payments, and acreage restrictions is developed and tested. More than 95 percent of the variation in U.S. corn acreage during the study period can be associated with the selected policy variables. The approach suggested in this research appears to be applicable to other crops heavily influenced by government policy.
The chemistry of N-substituted benzotriazoles : a novel route to dienamines

Abstract Readily prepared 1,3-bisbenzotriazolyl tertiary amines were converted into dienamines via the elimination of benzotriazole moieties with sodium hydride in tetrahydrofuran. Yields compare favourably with other methods.
Pricing Regulation and Imperfect Competition on the Massachusetts Health Insurance Exchange

Abstract We analyze insurance-pricing regulation under imperfect competition on the Massachusetts health insurance exchange. Differential markups lead to price variation apart from cost variation. Coarse insurer pricing strategies identify consumer demand. Younger consumers are twice as price sensitive as older consumers. Older consumers thus face higher markups over costs. Modified community rating links prices for consumers differing in both costs and preferences, and changes the marginal consumer firms face. Stricter regulations transfer resources from low-cost to high-cost consumers, reduce firm profits, and increase overall consumer surplus.
How to improve the calibration of cost models

One of software engineering's long-standing problems is to estimate the cost of a software project. Using the volume or size of a program to estimate the cost is a common practice in many software development organizations. However, in many situations one is unable to observe the value of this variable at the beginning of the project; one has to estimate it. In this paper we introduce a fairly general model which permits a surrogate or a proxy variable to be observed instead of the actual size. Under this model we obtain estimation of software cost at the given value of a surrogate variable. A confidence interval is also provided under this model.
Graphene-Side-Gate Engineering

Various mesoscopic devices exploit electrostatic side gates for their operation. In this letter, we investigate how voltage biasing of graphene side gates modulates the electrical transport characteristics of a graphene channel. We explore myriads of typical side-gated devices such as symmetric dual-side gates and asymmetric single-side gates, in monolayer and bilayer graphene. The side gates modulate the electrostatic doping in the graphene channel whose effect is reflected in transport measurement. This modulation efficiency is systematically characterized for all our devices and agrees well with the modeling presented.
How Much Is Poultry Litter Worth

Land-applying poultry litter to nutrient-deficient soils instead of commercial fertilizer could absorb nutrients from concentrated poultry production areas and help crop farmers. A survey of potential litter users showed that although farmers have used/are interested in using litter, there are still some problems that prevent the market from fully developing.
Prospective Evaluation of the Accuracy of MDCT Angiography for Living Kidney Donor

Purpose: In donor nephrectomy, it is important to understand the exact anatomy of the blood vessels during minimally invasive surgery. We prospectively analyzed the accuracy of the vessel structures obtained by use of 64-row multi-detector computed tomography (MDCT) angiography compared with the actual vessel structure observed during surgery. Materials and Methods: We analyzed 238 patients who underwent donor nephrectomy from July 2007 to August 2010. Before the operation, MDCT angiography was performed, and after the operation, the surgeons themselves wrote the protocol. The ipsilateral artery, the number of veins, the association with the run of the hilar vessel, and other vascular anomalies in computed tomography (CT) angiography and in the donor protocol were summarized. Results: Among 238 patients, nephrectomy was performed on the left side in 199 patients. The accuracy of MDCT for the artery and the vein was 93.3% and 92.4%, respectively. Accuracy did not differ significantly on the left and right sides (artery: p=0.124; vein: p=0.174). In 199 patients, the CT findings for the lumbar vein were compared with the surgical findings. The overall accuracy was shown to be 84.9%, and the accuracy of the group drained to the inferior vena cava (54%) was significantly different (p＜0.01) from that of the group drained to the renal vein (98.6%). Thus, it may be necessary to pay close attention to the interpretation of the findings for the lumbar vein. Conclusions: MDCT angiography is important for understanding the exact anatomy of blood vessels before minimally invasive surgery. We showed that 64-channel MDCT has high accuracy in the main vessel and hilar vessels. However, close attention to the interpretation of the CT findings for the lumbar vein may be required.
Isotope effects in C-H bond activation reactions by transition metals.

The activation of alkane C−H bonds by oxidative addition and its reverse reaction, reductive elimination, are believed to occur via transient σ-alkane complexes. This Account summarizes how isotope effects can be used to probe the nature of these intermediates and points out some pitfalls in interpreting kinetic data. Comparisons are made with arene C−H activation and other activation systems.
Approximation Algorithms for Model-Based Compressive Sensing

Compressive sensing (CS) states that a sparse signal can be recovered from a small number of linear measurements, and that this recovery can be performed efficiently in polynomial time. The framework of model-based CS (model-CS) leverages additional structure in the signal and provides new recovery schemes that can reduce the number of measurements even further. This idea has led to measurement-efficient recovery schemes for a variety of signal models. However, for any given model, model-CS requires an algorithm that solves the model-projection problem: given a query signal, report the signal in the model that is closest to the query signal. Often, this optimization can be computationally very expensive. Moreover, an approximation algorithm is not sufficient for this optimization to provably succeed. As a result, the model-projection problem poses a fundamental obstacle for extending model-CS to many interesting classes of models. In this paper, we introduce a new framework that we call approximation-tolerant model-CS. This framework includes a range of algorithms for sparse recovery that require only approximate solutions for the model-projection problem. In essence, our work removes the aforementioned obstacle to model-CS, thereby extending model-CS to a much wider class of signal models. Interestingly, all our algorithms involve both the minimization and the maximization variants of the model-projection problem. We instantiate this new framework for a new signal model that we call the constrained earth mover distance (CEMD) model. This model is particularly useful for signal ensembles, where the positions of the nonzero coefficients do not change significantly as a function of spatial (or temporal) location. We develop novel approximation algorithms for both the maximization and the minimization versions of the model-projection problem via graph optimization techniques. Leveraging these algorithms and our framework results in a nearly sample-optimal sparse recovery scheme for the CEMD model.
Demystifying Dutch disease

This paper examines the theory of Dutch disease and its implications for practical policy questions. Dutch disease is a term that is well-known to economists and development practitioners. But it is also a concept that is often conflated with "resource curse" and misinterpreted as a "disease" that necessarily causes adverse impacts on the economy. The paper points out that many of the seemingly well-established arguments in this field are not necessarily grounded in theory or empirical evidence. Great care is needed in diagnosing Dutch disease and formulating policy prescriptions based on the theoretical framework, given the restrictive assumptions that may not be fully applicable and the limited relevance to today's inextricably intertwined trade flows.
Actinide Organometallic Chemistry

The stoichiometric and catalytic chemistry of metal-organic compounds having actinide-to-carbon bonds is in a stage of rapid growth. Chemical, structural, and bonding characteristics have been identified which differ in interesting and informative ways from those of d-block transition element compounds.
Against the Wind: Labor Force Participation of Women and Economic Instability in Iran

ABSTRACTIn the last three decades, Iranian women's educational attainment has continuously increased while their fertility rate has fallen rapidly. Yet in spite of these developments, which in many countries have a positive effect on women's labor force participation, female labor force participation (FLFP) rates have remained at low levels. This paper argues that despite its overall static trend, FLFP of some Iranian women responded to economic pressures induced by macroeconomic instabilities. Looking at the Iranian economic crisis of 1994–5, the study shows that, controlling for individual fixed effects, married women in rural areas and never-married women in urban areas increased their participation rate by as much as 38 percent. No change in hours worked was found for any group of women. The differences in responses and their underlying reasons have policy implications for many developing countries.
Hot-gas-side and coolant-side heat transfer in liquid rocket engine combustors

The objectives of this article are to develop a multidisciplinary, computational methodology to predict the hot-gas-side and coolant-side heat transfer in film cooling assisted, regeneratively cooled liquid rocket engine combustors, and to use it in parametric studies to recommend optimized design of the coolant channels for a developmental combustor. An integrated numerical model which incorporates computational fluid dynamics (CFD) for the hot-gas thermal environment, and thermal analysis for the liner and coolant channels, was developed. This integrated CFD/thermal model was validated by comparing predicted heat fluxes with those of hot-firing test and industrial design methods for a 40-k calorimeter thrust chamber and the Space Shuttle Main Engine main combustion chamber. Parametric studies were performed for the advanced main combustion chamber to find a strategy for a proposed coolant channel design.
Modelling of Tgs Growth in Space

Attention is called to the necessity of programming the temperature downward in order to maintain a constant growth rate in the absence of convection. Trial and error numerical computations are performed to find the first approximation for the required isothermal dissolution period, linear ramp, and polynomial temperature variation period. The linear ramp rate is limited by the specified maximum temperature gradient. The isothermal dissolution turns out to be unnecessary. The linear ramp must be stopped before the polynomial period is begun in order to avoid overshooting the specified maximum growth rate. After a few hours, the temperature profile approaches steady-state behavior.
The Green Bank Telescope

The NRAO Robert C. Byrd Green Bank Telescope is a new 100 meter radio telescope that is now in routine astronomical operation. This paper gives a status report on astronomical performance, operational capabilities, development plans, and early scientific highlights. The telescope is now in regular operation to frequencies of 50 GHz, which achieves the base design goal of the facility. Both the surface and pointing accuracies allow good performance at that frequency. The active surface of 2004 movable panels is in regular use at all frequencies above ~8 GHz and significantly improves both gain and diffraction beam shape at high and low elevation angles. Receivers exist at most primary observing frequencies ranging from ~290 MHz to 50 GHz. A 256k-channel correlation spectrometer with up to 16 independent inputs is in routine use for spectroscopy. Backends for pulsar observing, broadband continuum, Very Long Baseline Interferometry, and planetary radar reception also exist. An advanced development program for enhancing the performance of the GBT is also underway. This program includes the Precision Telescope Control Project that will extend operation to 115 GHz or 2.6 mm wavelength (see the paper by Prestage and Constantikes in this volume), a 26-40 GHz receiver, a 68-92 GHz receiver, a fast sampling continuum backend built by a Caltech/NRAO collaboration, and a 64-pixel bolometer camera developed by a consortium of UPenn, NASA-GSFC, NIST, UCardiff, and NRAO. Software development projects for enhanced user interfaces and data handling are underway, and plans to implement queue-based dynamic scheduling and remote observing are being developed. The status of these projects and their anticipated scientific impact will be discussed.
Three-Dimensional Numerical Simulation and Performance Study of an Industrial Helical Static Mixer

In many branches of processing industries, viscous liquids need to be homogenized in continuous operations. Consequently, fluid mixing plays a critical role in the success or failure of these processes. Static mixers have been utilized over a wide range of applications such as continuous mixing, blending, heat and mass transfer processes, chemical reactions, etc. This paper describes how static mixing processes of single-phase viscous liquids can be simulated numerically, presents the flow pattern through a helical static mixer, and provides useful information that can be extracted from the simulation results. The three-dimensional finite volume computational fluid dynamics code used here solves the Navier-Stokes equations for both laminar and turbulent flow cases. The turbulent flow cases were solved using k-ω model and Reynolds stress model (RSM). The flow properties are calculated and the static mixer performance for different Reynolds numbers (from creeping flows to turbulent flows) is studied. A new parameter is introduced to measure the degree of mixing quantitatively. Furthermore, the results obtained by k-ω and RSM turbulence models and various numerical details of each model are compared. The calculated pressure drop is in good agreement with existing experimental data.
6-Thio-2′-deoxyinosine: Synthesis, incorporation, and evaluation as a postsynthetically modifiable base in oligonucleotides

Abstract The synthesis of 6-thio-2′-deoxyinosine (d S6 I) in a form suitably protected for solid-phase oligonucleotide synthesis is reported. This thionucleic acid was incorporated in high yield into short oligodeoxynucleotides, and the thiocarbonyl group could be modified by S-alkylation with complete chemoselectivity. The quantitation of incorporation and facile post-synthetic modification was demonstrated by enzymatic digestion and HPLC analysis, and the effect of covalent alkylation was determined by ΔT m measurements of the corresponding duplex oligonucleotides with dC as the complementary base.
LEDS: Providing Location-Aware End-to-End Data Security in Wireless Sensor Networks

Providing desirable data security, that is, confidentiality, authenticity, and availability, in wireless sensor networks (WSNs) is challenging, as a WSN usually consists of a large number of resource constraint sensor nodes that are generally deployed in unattended/hostile environments and, hence, are exposed to many types of severe insider attacks due to node compromise. Existing security designs mostly provide a hop-by-hop security paradigm and thus are vulnerable to such attacks. Furthermore, existing security designs are also vulnerable to many types of denial of service (DoS) attacks, such as report disruption attacks and selective forwarding attacks and thus put data availability at stake. In this paper, we seek to overcome these vulnerabilities for large-scale static WSNs. We come up with a location-aware end-to-end security framework in which secret keys are bound to geographic locations and each node stores a few keys based on its own location. This location-aware property effectively limits the impact of compromised nodes only to their vicinity without affecting end-to-end data security. The proposed multifunctional key management framework assures both node-to-sink and node-to-node authentication along the report forwarding routes. Moreover, the proposed data delivery approach guarantees efficient en-route bogus data filtering and is highly robust against DoS attacks. The evaluation demonstrates that the proposed design is highly resilient against an increasing number of compromised nodes and effective in energy savings.
Effects of Zirconia on Microstructure and Dielectric Properties of Barium Titanate Ceramics

Dielectric properties and structural characteristics of BaTiO3 ceramics are significantly influenced by small addition (2 wt%) of ZrO2. SEM and TEM observations revealed enhanced microstructural uniformity and retarded grain growth depending on sintering temperature. Above 1320°C, Zr diffusion into the BaTiO3 lattice resulted in a chemical modification of the tetragonal structure and the development of core–shell grains. Below 1320°C, TEM analysis showed ZrO2 at the grain boundaries as discrete particles (∼0.03μm). X-ray diffraction analysis revealed a decrease in the axial (c/a) ratio with decreasing grain size. A corresponding decrease in the spontaneous polarization, and twinned domain structures, were also observed in the fine-grained ceramics. These samples also showed a flattened permittivity response with temperature and significantly lower losses.
The first enantiospecific total synthesis of a C-quaternary voachalotine alkaloid, (+)-dehydrovoachalotine

Abstract The first enantiospecific total synthesis of the indole alkaloid (+)-dehydrovoachalotine ( 1 ) has been achieved from d -(+)-tryptophan methyl ester in 28% overall yield. The formation of the prochiral quaternary carbon center at C-16 in the key intermediate ( 12 ) was realized via a Tollens reaction from N a -methylvellosimine ( 13 ) in 95% yield. This approach could also be applied to the synthesis of many other indole alkaloids that contain a quaternary carbon center at C(16).
Synchrotron X-ray Powder Diffraction and Electronic Band Structure of α- and β-Cu2ZnSiS4

The quaternary diamond-like semiconductor, Cu2ZnSiS4, was synthesized by high-temperature solid-state synthesis at 1000 °C. High-resolution synchrotron X-ray powder diffraction of this product revealed the presence of two polymorphs. This data confirms that the known α-Cu2ZnSiS4 exists with the wurtz-stannite structure in the noncentrosymmetric space group Pmn21. The new polymorph, β-Cu2ZnSiS4, crystallizes in the noncentrosymmetric space group Pn with a = 6.134092(6) A, b = 6.392752(5) A, c = 7.421228(8) A, β = 90.056(1)°, Z = 2, χ2 = 5.554, Rp = 0.0857 and wRp = 0.1173. Electronic structure calculations performed for both polymorphs indicate direct bandgaps of 1.3 and 1.7 eV at the Γ-point, respectively.
Verification and Validation in Computational Fluid Dynamics

Abstract Verification and validation (V&V) are the primary means to assess accuracy and reliability in computational simulations. This paper presents an extensive review of the literature in V&V in computational fluid dynamics (CFD), discusses methods and procedures for assessing V&V, and develops a number of extensions to existing ideas. The review of the development of V&V terminology and methodology points out the contributions from members of the operations research, statistics, and CFD communities. Fundamental issues in V&V are addressed, such as code verification versus solution verification, model validation versus solution validation, the distinction between error and uncertainty, conceptual sources of error and uncertainty, and the relationship between validation and prediction. The fundamental strategy of verification is the identification and quantification of errors in the computational model and its solution. In verification activities, the accuracy of a computational solution is primarily measured relative to two types of highly accurate solutions: analytical solutions and highly accurate numerical solutions. Methods for determining the accuracy of numerical solutions are presented and the importance of software testing during verification activities is emphasized. The fundamental strategy of validation is to assess how accurately the computational results compare with the experimental data, with quantified error and uncertainty estimates for both. This strategy employs a hierarchical methodology that segregates and simplifies the physical and coupling phenomena involved in the complex engineering system of interest. A hypersonic cruise missile is used as an example of how this hierarchical structure is formulated. The discussion of validation assessment also encompasses a number of other important topics. A set of guidelines is proposed for designing and conducting validation experiments, supported by an explanation of how validation experiments are different from traditional experiments and testing. A description is given of a relatively new procedure for estimating experimental uncertainty that has proven more effective at estimating random and correlated bias errors in wind-tunnel experiments than traditional methods. Consistent with the authors’ contention that nondeterministic simulations are needed in many validation comparisons, a three-step statistical approach is offered for incorporating experimental uncertainties into the computational analysis. The discussion of validation assessment ends with the topic of validation metrics, where two sample problems are used to demonstrate how such metrics should be constructed. In the spirit of advancing the state of the art in V&V, the paper concludes with recommendations of topics for future research and with suggestions for needed changes in the implementation of V&V in production and commercial software.
Velocity occupancy space for differential drive vehicles

Velocity occupancy space (VOS) was developed to allow a vehicle to avoid moving and stationary obstacles and navigate efficiently to a goal using only uncertain sensor data. However, the VOS concept was designed for a holonomic vehicle capable of instantaneous velocity changes, capabilities that are not possessed by real vehicles. Therefore, this paper presents two methods by which velocity occupancy space can be adapted to work within the kinodynamic constraints of a differential drive vehicle with bounded acceleration capabilities. These two methods are suitable under different environmental and vehicle conditions so they are combined in order to allow the best method to be selected for every time step. Numerous simulation trials have been used to demonstrate the relative strengths and weakness of the two base methods and the resulting combined method.
Synthesis of 2-spirocyclopropylglucose via condensation of erythrose with the lithium enolate of 2,6-di-tert=butyl-4-methylphenyl cyclopropanecarboxylate

Abstract Glyceraldehyde, erythrose, and threose are condensed with the enolate derived from cyclopropanecarboxylic acid BHT ester. The conversion of two diastereomeric products of this condensation into new 2-spirocyclopropyl-substituted aldopyranoses is described.
Finding the k Shortest Paths in Parallel

A concurrent-read exclusive-write PRAM algorithm is developed to find the k shortest paths between pairs of vertices in an edge-weighted directed graph. Repetitions of vertices along the paths are allowed. The algorithm computes an implicit representation of the k shortest paths to a given destination vertex from every vertex of a graph with n vertices and m edges, using O(m+nk log 2 k) work and O( log^3k log ^*k+ log n( log log k+ log ^*n)) time, assuming that a shortest path tree rooted at the destination is pre-computed. The paths themselves can be extracted from the implicit representation in O( log k + log n) time, and O(n log n +L) work, where L is the total length of the output.
Counting permutations by congruence class of major index

Consider S"n, the symmetric group on n letters, and let [email protected] denote the major index of @[email protected]?S"n. Given positive integers k,l and nonnegative integers i,j, definem"n^k^,^l(i,j):=#{@[email protected]?S"n:[email protected]=i(mod k) and [email protected]^-^1=j(mod l)}. We give a bijective proof of the following result which had been previously proven by algebraic methods: If k,l are relatively prime and at most n thenm"n^k^,^l(i,j)=n!kl which, surprisingly, does not depend on i and j. Equivalently, if m"n^k^,^l(i,j) is interpreted as the (i,j)-entry of a matrix m"n^k^,^l, then this is a constant matrix under the stated conditions. This bijection is extended to show the more general result that, for d>=1 and k,l relatively prime, the matrix m"n^k^d^,^l^d admits a block decomposition where each block is the matrix m"n^d^,^d/(kl). We also give an explicit formula for m"n^n^,^n, and show that if p is prime then m"n"p^p^,^p has a simple block decomposition. To prove these results, we use the representation theory of the symmetric group and certain restricted shuffles.
Computational method for acoustic wave focusing

Scattering properties of a material are changed when the material is injected with small acoustically soft particles. It is shown that its new scattering behaviour can be understood as a solution of a potential scattering problem with the potential q explicitly related to the density of the small particles. In this paper we examine the inverse problem of designing a material with the desired focusing properties. An algorithm for solving such a problem is examined from the theoretical as well as from the numerical points of view.
The Present and Future of Empirical Finance

More and more data, greatly increased computing power, a rising number of research enthusiasts, an increased number of finance journals, and sophisticated techniques have been the characteristics of empirical finance in the past 30 years. Topics of current interest relate to conditional means, conditional variances, and conditional distributions. These topics will remain in the forefront for years to come and perhaps be joined by questions that will shake the foundations of finance theory. For example, will we find that market data are characterized by jump diffusions—that is, diffusions with breaks—rather than standard diffusions?
IMPACT OF DISASTERS ON FIRMS IN DIFFERENT SECTORS: IMPLICATIONS FOR SUPPLY CHAINS

Disasters keep damaging infrastructure, disrupting supply chains and affecting firm profitability. There is an urgent need for better understanding of disaster impact on supply chains but very few publications address this issue. This exploratory study takes an indirect approach and investigates disaster impact on firms in various industry sectors. This approach allows us to take full advantage of large secondary data bases of firm and disaster data in order to analyze the impact of over 3,500 disasters on more than 100,000 firm-year observations over 15 years. Our results indicate that disasters impact all sectors within a supply chain. We found that damage by windstorms and floods seem to be dramatically different from that of an earthquake, providing evidence against the all-hazards approach. We also show that the impact of floods on total asset turnover of a firm is dependent on the firm's position in the supply chain. We found that while upstream partners enjoy a positive impact, downstream partners have to plan for the opposite. Supply chain managers can use our results to better understand disaster impact on their business. Our study suggests a supply chain–wide mitigation strategy rather than a company-specific one.
WHEN DO TWO PLANTED GRAPHS HAVE THE SAME COTRANSVERSAL MATROID

Cotransversal matroids are a family of matroids that arise from planted graphs. We prove that two planted graphs give the same cotransversal matroid if and only if they can be obtained from each other by a series of local moves.
EXPLOSIVE BEHAVIOR IN THE 1990s NASDAQ: WHEN DID EXUBERANCE ESCALATE ASSET VALUES? *

A recursive test procedure is suggested that provides a mechanism for testing explosive behavior, date-stamping the origination and collapse of economic exuberance, and providing valid confidence intervals for explosive growth rates. The method involves the recursive implementation of a right-side unit root test and a sup test, both of which are easy to use in practical applications, and some new limit theory for mildly explosive processes. The test procedure is shown to have discriminatory power in detecting periodically collapsing bubbles, thereby overcoming a weakness in earlier applications of unit root tests for economic bubbles. Some asymptotic properties of the Evans (1991) model of periodically collapsing bubbles are analyzed and the paper develops a new model in which bubble duration depends on the strength of the cognitive bias underlying herd behavior in the market. The paper also explores alternative propagating mechanisms for explosive behavior based on economic fundamentals under time varying discount rates. An empirical application to the Nasdaq stock price index in the 1990s provides confirmation of explosiveness and date-stamps the origination of financial exuberance to June 1995, prior to the famous remark in December 1996 by Alan Greenspan about irrational exuberance in financial markets, thereby giving the remark empirical content.
On Penrose limits and gauge Theories

We discuss various Penrose limits of conformal and nonconformal backgrounds. InAdS5£T 1;1 , for a particular choice of the angular coordinate inT 1;1 the resulting Penrose limit coincides with the similar limit forAdS5£S 5 . In this case an identiflcation of a subset of fleld theory operators with the string zero mode creation operators is possible. For another limit we obtain a light-cone string action that resembles a particle in a magnetic fleld. We also consider three difierent types of backgrounds that are dual to nonconformal fleld theories: The Schwarzschild black hole in AdS5, D3-branes on the small resolution of the conifold and the Klebanov-Tseytlin background. We flnd that in all three cases the introduction of nonconformality renders a theory that is no longer exactly solvable and that the form of the deformation is universal. The corresponding world sheet theory in the light-cone gauge has a ? = x + dependent mass term.
Variations on a Theme of Cline and Donkin

Let N be a normal subgroup of a group G. An N-module Q is called G-stable provided that Q is equivalent to the twist Q g of Q by g, for every g ∈ G. If the action of N on Q extends to an action of G on Q, then Q is obviously G-stable, but the converse need not hold. A famous conjecture in the modular representation theory of reductive algebraic groups G asserts that the (obviously G-stable) projective indecomposable modules (PIMs) Q for the Frobenius kernels G r (r ≥ 1) of G have a G-module structure. It is sometimes just as useful (for a general module Q) to know that a finite direct sum Q ⊕ n of Q has a compatible G-module structure. In this paper, this property is called numerical stability. In recent work (Parshall and Scott, Adv Math 226:2065–2088, 2011), the authors established numerical stability in the special case of PIMs. We provide in this paper a more general context for that result, working in the context of k-group schemes and a suitable version of G-stability, called strong G-stability. Among our results here is the determination of necessary and sufficient conditions for the existence of a compatible G-module structure on a strongly G-stable N-module, in the form of a cohomological obstruction which must be trivial precisely when the G-module structure exists. Our main result is achieved by giving an approach to killing the obstruction by tensoring with certain finite dimensional G/N-modules.
A method for computing the interval of delay values for which a differential-delay system is stable

A test for determining the interval of delay values for which delay-differential system is asymptotically stable is presented, i.e. an explicit method is given for calculating h*, such that, for 0 >
Risk Premiums in Dynamic Term Structure Models with Unspanned Macro Risks

This paper quanties how variation in real economic activity and ination in the U.S. inuenced the market prices of level, slope, and curvature risks in U.S. Treasury markets. To accomplish this we develop a novel arbitrage-free DTSM in which macroeconomic risks{ in particular, real output and ination risks{ impact bond investment decisions separately from information about the shape of the yield curve. Estimates of our preferred macro-DTSM over the twenty-three year period from 1985 through 2007 reveal that unspanned macro risks explained a substantial proportion of the variation in forward terms premiums. Unspanned macro risks accounted for nearly 90% of the conditional variation in short-dated forward term premiums, with unspanned real economic growth being the key driving factor. Over horizons beyond three years, these eects were entirely attributable to unspanned ination. Using our model, we also reassess some of Chairman Bernanke’s remarks on the interplay between term premiums, the shape of the yield curve, and macroeconomic activity.
Efficient Replication Bypass of Size‐Expanded DNA Base Pairs in Bacterial Cells

One of the long-standing aims of biomimetic chemistry has been to develop molecules that function as much as possible as the natural ones do.[1] Among the biopolymers, the nucleic acids have long served as a test bed for bio-inspired design. The earliest focus of altered structures for DNA was in the redesign of the phosphodiester backbone,[2] and numerous studies found backbone variants that assembled well into helices. In addition, in recent years, some altered sugars have also been shown to be substrates for certain polymerase enzymes.[3] Such work suggests the possibility of future biological activities associated with altered DNA backbones.
An experimental approach to valuing new differentiated products

Abstract An experimental store was created to evaluate initial demand for locally produced and guaranteed tender steak products as a more realistic alternative to contingent valuation (CV) and dichotomous-choice experimental methods. Strengths of the approach are incentive compatibility, a realistic consumption set, and a familiar choice environment. Consumers selected among USDA Choice, premium quality, lean, guaranteed tender and locally produced strip steaks. A double-hurdle count data model indicated initial willingness-to-pay (WTP) for locally produced steak comparable to prior CV results, but demand was highly elastic. Demand for premium quality steak crowded out demand for the guaranteed tender product, contrasting with prior dichotomous-choice experimental results.
Loan Officer Turnover and Credit Availability for Small Firms

This paper presents empirical evidence on the role loan officers play in facilitating small firm access to commercial bank loans. If loan officers use soft information (for example, assessments of character, information from customers and suppliers) to make lending decisions that would not otherwise be made on the basis of hard information (for example, tax returns or financial statements), then, frequent turnover in loan officers should be associated with an adverse effect on credit availability. This relationship is confirmed empirically using survey data of U.S. small firms in 1995 and 2001, where loan officer turnover is positively related to the turndown rate on the most recent loan application. Although loan officer turnover could be influenced by the turndown rate (for example, an owner changes banks and gets a new loan officer as a result of a recent turndown), its negative effect on credit availability persists under several different tests.
Valuing the Treasury's Capital Assistance Program

The Capital Assistance Program (CAP) was created by the U.S. government in February 2009 to provide backup capital to large financial institutions unable to raise sufficient capital from private investors. Under the terms of the CAP, a participating bank receives contingent capital by issuing preferred shares to the Treasury combined with embedded options for both parties: The bank gets the option to redeem the shares or convert them to common equity, with conversion mandatory after seven years; the Treasury earns dividends on the preferred shares and gets warrants on the bank's common equity. We develop a contingent claims framework in which to estimate market values of these CAP securities. The interaction between the competing options held by the buyer and issuer of these securities creates a game between the two parties, and our approach captures this strategic element of the joint valuation problem and clarifies the incentives it creates. We apply our method to the 18 publicly held bank holding companies that participated in the Supervisory Capital Assessment Program (the stress test) launched together with the CAP. On average, we estimate that compared to a market transaction, the CAP securities carry a net value of approximately 30% of the capital invested for a bank participating to the maximum extent allowed under the terms of the program. We also find that the net value varies widely across banks. We compare our estimates with abnormal stock price returns for the stress test banks at the time the terms of the CAP were announced; we find correlations between 0.78 and 0.85, depending on the precise choice of period and set of banks included. These results suggest that our valuation aligns with shareholder perception of the value of the program, prompting questions about industry reactions and the overall impact of the program. This paper was accepted by Wei Xiong, finance.
Pd-mediated synthesis of substituted benzenes fused with carbocycle/heterocycle

A new Pd-catalyzed one-pot multicomponent coupling reaction for the construction of benzene ring fused with carbocycle or heterocycle under a Cu-free condition is described.
State-Plane Analysis of Quasi-Resonant Converters

A comprehensive analysis of the high-frequency quasiresonant buck converter is presented using the graphical state-plane technique. The analysis has revealed, for the first time, the presence of several unfamiliar modes of operation. The voltage-conversion ratio and boundary-switching frequency for each mode are derived. The existence of various operating modes are verified experimentally.
A dynamic games approach to controller design: disturbance rejection in discrete-time

It is shown that the discrete-time disturbance rejection problem, formulated in finite and infinite horizons, and under perfect state measurements, can be solved by making direct use of some results on linear-quadratic zero-sum dynamic games. For the finite-horizon problem an optimal (minimax) controller exists, and can be expressed in terms of a generalized (time-varying) discrete-time Riccati equation. The existence of an optimum also holds in the infinite-horizon case, under an appropriate observability condition, with the optimal control, given in terms of a generalized algebraic Riccati equation, also being stabilizing. In both cases, the corresponding worst-case disturbances turn out to be correlated random sequences with discrete distributions, which means that the problem (viewed as a dynamic game between the controller and the disturbance) does not admit a pure-strategy saddle point. Results for the delayed state measurement and the nonzero initial state cases are presented. >
New definition of TMD parton densities

I give an account of a new definition of transverse-momentum-dependent parton densities. The new definition solves a number of difficulties and inconsistencies in earlier definitions.
Spectrum conservation by efficient channel utilization

The growth of the communication industry has resulted in ever-increasing demands on the radio spectrum. This, in turn, has spurred the exploitation of previously unused frequency bands and the development of techniques for making better use of those already available. In this paper, spectral utilization is examined using the information-theory techniques of Shannon. The power-bandwidth tradeoff for the ideal channel is established and the performance of practical analog and digital modulation techniques is compared with this ideal. It is shown that well-designed systems tend to operate near the "knee" of the power-bandwidth tradeoff curve for the ideal channel and that they are frequently within 10 dB or less of the performance of the ideal.
See and avoidance behaviors for autonomous navigation

Recent advances in many multi-discipline technologies have allowed small, low-cost fixed wing unmanned air vehicles (UAV) or more complicated unmanned ground vehicles (UGV) to be a feasible solution in many scientific, civil and military applications. Cameras can be mounted on-board of the unmanned vehicles for the purpose of scientific data gathering, surveillance for law enforcement and homeland security, as well as to provide visual information to detect and avoid imminent collisions for autonomous navigation. However, most current computer vision algorithms are highly complex computationally and usually constitute the bottleneck of the guidance and control loop. In this paper, we present a novel computer vision algorithm for collision detection and time-to-impact calculation based on feature density distribution (FDD) analysis. It does not require accurate feature extraction, tracking, or estimation of focus of expansion (FOE). Under a few reasonable assumptions, by calculating the expansion rate of the FDD in space, time-to-impact can be accurately estimated. A sequence of monocular images is studied, and different features are used simultaneously in FDD analysis to show that our algorithm can achieve a fairly good accuracy in collision detection. In this paper we also discuss reactive path planning and trajectory generation techniques that can be accomplished without violating the velocity and heading rate constraints of the UAV.