cssi/SciSciGPT-SciSciNet huggingface dataset:
Structural optimization for joined-wing synthesis

The joined wing is an innovative aircraft configuration with a rear wing, or horizontal tail, that is attached near the top of the vertical tail and sweeps forward to join the trailing edge of the main wing. This study evaluates two structural design methods for application in an aircraft synthesis code and quantifies the differences between these methods for joined wings in terms of weight, stress, direct operating cost, and computational time. A minimum weight optimization method and a fully stressed design method are used to design joined-wing structures. Both methods determine the sizes of 204 structural members, satisfying 1020 stress constraints and five buckling constraints. Monotonic splines are shown to be a very effective way of linking spanwise distributions of material to a few design variables. Five beam buckling constraints for the horizontal tail are included in both design methods. Without this constraint on buckling, the fully stressed design is shown to be very similar to the minimum weight structure. Adding a beam buckling constraint for the horizontal tail increased the structural weight by 13% and produced a fully stressed design that is 0.9% heavier than the minimum weight structure. Using the minimum weight optimization method to design the structure and to save 0.9% in weight required 20 times the computational time. Furthermore, the minimum weight structure produced only a 0.02% savings in direct operating cost. This study suggests that a fully stressed design method based on nonlinear analysis is adequate for a joined-wing synthesis study. The same joined wing considered in this study was shown, in an earlier study, to be slightly more expensive to operate than a conventional configuration designed for the same medium range transport mission. Since the same fully stressed design method was used in this earlier study, this work supports the comparisons of joined-wing and conventional aircraft performance presented in the earlier study. Of course, a different set of mission specifications and design assumptions may produce joined wings that perform significantly better.
MiddleWhere: a middleware for location awareness in ubiquitous computing applications

Location awareness significantly enhances the functionality of ubiquitous computing services and applications, and enriches the way they interact with users and resources in the environment. Many different alternative or complementary location sensing technologies are available. However, these technologies give location information in different formats and with different resolution and confidence. In this paper we introduce "MiddleWhere" a distributed middleware infrastructure for location that separates applications from location detection technologies. MiddleWhere enables the fusion of different location sensing technologies and facilitates the incorporation of additional location technologies on the fly as they become available. MiddleWhere utilizes probabilistic reasoning techniques to resolve conflicts and deduce the location of people given different sensor data. Besides, it allows applications to determine various kinds of spatial relationships between mobile objects and their environment, which is key in enabling a strong coupling between the physical and virtual world, as emphasized by ubiquitous computing. We have integrated MiddleWhere with our ubiquitous computing infrastructure, and have verified its flexibility and usefulness by incorporating various location sensing technologies and building a number of location-sensitive applications on top of it.
Chaotic scrambling for wireless analog video

Abstract We report the implementation of a novel in-band chaotic scrambler for securing wireless analog video. In this demonstration system, an analog video signal is injected into a chaotic oscillator and the output is transmitted through a standard wireless radio link. At the receiver, a descrambler separates the video from the chaotic signal in real time. Experimental results show the scrambled signal effectively hides the original video image, yet the descrambler recovers the original color video with reasonable clarity and detail. Compared to digital encryption, chaotic scrambling offers an efficient, low-cost alternative for masking time-critical analog communications.
ACTIVATION ANALYSIS AND DENDROCHRONOLOGY FOR ESTIMATING POLLUTION HISTORIES

Neutron activation analyses of wood shavings from tree rings have shown that plant tissues grown through periods of varying environmental conditions keep permanent records of the trace elements they received through nutrients from their immediate surroundings. Detailed examination of several species of trees, along with dendrochronological data, suggest the possibilities of utilizing this technique for pollution monitoring as well as for developing valuable information for environmental modelling.
Banking panics of the Gilded Age

1. The bank panic experience: an overview 2. The banking panic of 1873 3. Two incipient banking panics of 1884 and 1890: an unheralded success story 4. The banking panic of 1893 5. The trust company panic of 1907 6. Were panics of the national banking era preventable? 7. Epilogue Appendix References Index.
Wavenumber calibration tables from heterodyne frequency measurements

This new calibration atlas is based on frequency rather than wavelength calibration techniques for absolute references. Since a limited number of absolute frequency measurements is possible, additional data from alternate methodology are used for difference frequency measurements within each band investigated by the frequency measurements techniques. Data from these complementary techniques include the best Fourier transform measurements available. Included in the text relating to the atlas are a description of the heterodyne frequency measurement techniques and details of the analysis, including the Hamiltonians and least-squares-fitting and calculation. Also included are other relevant considerations such as intensities and lincshape parameters. A 390-entry bibliography which contains all data sources used and a subsequent section on errors conclude the text portion. The primary calibration molecules are the linear triatomics, carbonyl sulfide and nitrous oxide, which cover portions of the infrared spectrum ranging from 488 to 3120 cm-1. Some gaps in the coverage afforded by OCS and N2O are partially covered by NO, CO, and CS2. An additional region from 4000 to 4400 cm-1 is also included. The tabular portion of the atlas is too lengthy to include in an archival journal. Furthermore, different users have different requirements for such an atlas. In an effort to satisfy most users, we have made two different options available. The first is NIST Special Publication 821, which has a spectral map/facing table format. The spectral maps (as well as the facing tables) are calculated from molecular constants derived for the work. A complete list of all of the molecular transitions that went into making the maps is too long (perhaps by a factor of 4 or 5) to include in the facing tables. The second option for those not interested in maps (or perhaps to supplement Special Publication 821) is the complete list (tables-only) which is available in computerized format as NIST Standard Reference Database #39, Wavelength Calibration Tables.
Regulating tobacco: the need for a public health judicial decision-making canon.

The U.S. Supreme Court has unnecessarily injured the public's health through its decisions in three tobacco cases. Perhaps the recognition of a judicial decision-making canon that makes public health concerns legally relevant could produce more supportive decisions in the future.
Synthesis of aryl ketones or ketimines by palladium-catalyzed arene C-H addition to nitriles.

The unprecedented palladium-catalyzed C−H addition of arenes to nitriles provides moderate to excellent yields of aryl ketones or the corresponding hindered imines. The addition of a small amount of DMSO increases the yields dramatically. Both intermolecular and intramolecular reactions are successful, although the intramolecular reactions tend to be more sluggish. This novel chemistry is believed to involve palladium-catalyzed C−H activation of the arene by electrophilic aromatic substitution, followed by the unusual carbopalladation of a nitrile. Similar reactions have been successfully developed employing arylboronic acids and nitriles. A concise route to xanthones starting from cheap starting materials has been developed employing this synthetic protocol.
ON THE USE OF DIFFERING MONEY TRANSMISSION METHODS BY MEXICAN IMMIGRANTS

Interest in the factors shaping migrants' use of a given money transmittal method has recently intensified following researchers' agreement on the often inadequate infrastructure surrounding remittances transfers. This concern has also captured the attention of government officials, who appear more eager to promote more efficient and safe transfers of emigrant's earnings given the potential that remittances hold for increasing resources at the disposal of receiving nations. This study uses data from Mexican immigrants who have resided in the United States to examine the various factors that shape migrants' use of the various methods to remit earnings to Mexico. We find, not surprisingly, that accessibility factors play a key role in explaining migrants' use of the various money-transfer mechanisms. Migrants are less likely to use banks and more likely to use nonbank money-transmitting services when they lack immigration documents. Additionally, migrants' awareness of alternative remitting methods, either through educational attainment, skill level, or networks of friends and family in the city to which they migrated, makes them more likely to use banks relative to the more expensive nonbank money-transmitting mechanisms. In contrast, the use of informal money transfer mechanisms (cash in the mail and hand-carried transfers) is more likely among workers with less regular employment - such as self-employed and specific-task workers, more newly arrived migrants, and migrants remitting to rural and poorer areas.
A single-chip pipelined 2-D FIR filter using residue arithmetic

Novel circuits and architecture for residue arithmetic are presented. These circuits are designed for fast and area-efficient single-chip implementation of digital signal processors. This has been achieved by following an algorithmic approach as opposed to the conventional look-up table approach. Substantial area savings have resulted. The circuits include a residue adder, residue multiplier, binary-to-residue converter, and residue-to-binary converter. Based on these circuits, a prototype single-chip, 3*3, finite impulse response (FIR), variable coefficient, linear phase filter has been designed and fabricated in standard 2- mu m CMOS technology. The filter has a pipelined architecture to increase the throughput. Testability in the form of scan-path registers has been incorporated. An interesting feature of this combination is the possible tradeoff available between the precision of the filter coefficients and the image data. The chip has a die size of 6.6*4.2 mm/sup 2/, dissipates 220 mW of power, and is synchronized with a 180-ns clock cycle. >
THE DARBOUX POINT AND THE CONJUGATE POINT ON OPTIMAL DEORBIT FOR REENTRY TRAJECTORIES

Abstract The concept of the Darboux point at which an extremal loses its global optimality is extended to the case of discontinuous control. Using Contensou's domain of maneuverability, the condition for optimal switching at a corner is derived and the optimality of the trajectory in the neighborhood of a Darboux point is analyzed. The theory is applied to the problems of minimum-fuel planar and noncoplanar deorbit from elliptical orbits for atmospheric entry at a prescribed angle. In each case, the global optimal trajectory is assessed and it is found that in these nonlinear problems the Darboux point and the conjugate point are distinct. The global optimality is always lost before local optimality.
MULTI-AGENT DIFFUSION OF DECISION EXPERIENCES

Diffusion geometry offers a fresh perspective on multi-scale information analysis, which is critical to multiagent systems that need to process massive data sets. A recent study has shown that when the "diffusion distance" concept is applied to human decision experiences, its performance on solution synthesis can be significantly better than using Euclidean distance. However, as a data set expands over time, it can quickly exceed the processing capacity of a single agent. In this paper, we proposed a multi-agent diffusion approach where a massive data set is split into several subsets and each diffusion agent only needs to work with one subset in diffusion computation. We conducted experiments with different splitting strategies applied to a set of decision experiences. The result indicates that the multi-agent diffusion approach is beneficial, and it is even possible to benefit from using a larger group of diffusion agents if their subsets have common experiences and pairly-shared experiences. Our study also shows that system performance could be affected significantly by the splitting granularity (size of each splitting unit). This study paves the road for applying the multi-agent diffusion approach to massive data analysis.
Densification and Properties of α‐Silicon Carbide

The sintering behavior of alpha-SiC with B and C sintering aids and without sintering aids was investigated experimentally. The sintering was performed for 30-60 min in argon flow at 2150 and 2200 C. The density of the sintered bars was determined by weighing and measuring the bars, four-point flexure tests were conducted on machined bars, and the Weibull modulus was determined by regression analysis. It is found that type 1 alpha-SiC powder, which does not densify, can be sintered to a high final density (in excess of 96 percent of the theoretical value) using B and C sintering aids. Flexure test results and Weibull modulus data suggest that the strength of the alpha-SiC ceramic is greatly affected by processing flaws and also by inclusions and machining flaws.
Adaptive output-feedback control of systems with output nonlinearities

A direct model-reference adaptive control scheme, which requires only output, rather than full-state, measurement is presented for a class of single-input, single-output (SISO) nonlinear systems with unknown constant parameters. The nonlinearities are not required to satisfy any growth conditions. The assumptions on the linear part of the nonlinear system are the same as in the standard adaptive control problem for linear systems, which appears as a special case of the nonlinear problem that is solved. >
Bucketing Coding and Information Theory for the Statistical High-Dimensional Nearest-Neighbor Problem

The problem of finding high-dimensional approximate nearest neighbors is considered when the data is generated by some known probabilistic model. A large natural class of algorithms (bucketing codes) is investigated, Bucketing information is defined, and is proven to bound the performance of all bucketing codes. The bucketing information bound is asymptotically attained by some randomly constructed bucketing codes. The example of n Bernoulli(1/2) very long (length d → ∞) sequences of bits is singled out. It is assumed that n - 2m sequences are completely independent, while the remaining 2m sequences are composed of m dependent pairs. The interdependence within each pair is that their bits agree with probability 1/2 0. A specific 2-D inequality (proven in another paper) implies that the exponent 1/p cannot be lowered. Moreover, if one sequence out of each pair belongs to a known set of n(2p-1)2 sequences, pairing can be done using order n1+∈ comparisons!
On-orbit characterization of blackbody emissivity and spectrometer instrument line-shape using quantum cascade laser based reflectometry

We present a method to characterize the emissivity of a spaceborne blackbody and the instrument line-shape (ILS) of a spectrometer using a quantum cascade laser (QCL) based reflectometer. QCLs allow the realization of on-orbit reflectometry that directly observes blackbody surface properties. We present experimental data verifying that the QCL reflected radiance signal can be measured by an Earth-observing spectrometer. The QCL can also be used to realize a monochromatic, spatially uniform source of infrared radiation to measure the spectrometer's ILS, which can be inverted to obtain diagnostic information about the integrity of the detector and nonlinearities in the detector signal-chain.
Reactions of Pd and Pt Complexes with Molecular Oxygen

Knowledge of exactly how metal complexes react with molecular oxygen is still limited and this has hampered efforts to develop catalysts for oxidation reactions using O2 as the oxidant and/or oxygen-atom source. A better understanding of the reactions of different types of metal complexes with O2 will be of great utility in rational catalyst development. Reactions between molecular oxygen and Pd(0-II) and Pt(0-IV) complexes are reviewed here.
Stereospecific preparation of (Z)-α-fluorostilbenes via a kinetically controlled palladium-catalyzed cross-coupling reaction of high E/Z ratio 1-bromo-1-fluorostyrenes and aryl stannanes

Abstract High E/Z ratios were obtained for 1-bromo-1-fluorostyrenes by isomerization from the original E/Z ratios of approximately 1:1. The palladium-catalyzed cross-coupling reaction of high E/Z ratio 1-bromo-1-fluorostyrenes with aryl stannanes gives (Z)-α-fluorostilbenes stereospecifically in good yields.
Boosting XML Filtering with a Scalable FPGA-based Architecture

growing amount of XML encoded data exchanged over the In- ternet increases the importance of XML based publish-subscribe (pub-sub) and content based routing systems. The input in such systems typically consists of a stream of XML documents and a set of user subscriptions expressed as XML queries. The pub-sub system then filters the published documents and passes them t o the subscribers. Pub-sub systems are characterized by very high input ratios, therefore the processing time is critical. In this p aper we propose a "pure hardware" based solution, which utilizes XPath query blocks on FPGA to solve the filtering problem. By utiliz - ing the high throughput that an FPGA provides for parallel pro- cessing, our approach achieves drastically better through put than the existing software or mixed (hardware/software) architectures. The XPath queries (subscriptions) are translated to regular expres- sions which are then mapped to FPGA devices. By introducing stacks within the FPGA we are able to express and process a wide range of path queries very efficiently, on a scalable environ ment. Moreover, the fact that the parser and the filter processing a re per- formed on the same FPGA chip, eliminates expensive communi- cation costs (that a multi-core system would need) thus enabling very fast and efficient pipelining. Our experimental evalua tion re- veals more than one order of magnitude improvement compared to traditional pub/sub systems.
Explaining the Poor Performance of Consumption-based Asset Pricing Models

We show that the external habit-formation model economy of Campbell and Cochrane ~1999! can explain why the Capital Asset Pricing Model ~CAPM! and its extensions are better approximate asset pricing models than is the standard consumptionbased model. The model economy produces time-varying expected returns, tracked by the dividend‐price ratio. Portfolio-based models capture some of this variation in state variables, which a state-independent function of consumption cannot capture. Therefore, though the consumption-based model and CAPM are both perfect conditional asset pricing models, the portfolio-based models are better approximate unconditional asset pricing models. THE DEVELOPMENT OF CONSUMPTION-BASED ASSET PRICING THEORY ranks as one of the major advances in financial economics during the last two decades. The classic papers of Lucas ~1978!, Breeden ~1979!, Grossman and Shiller ~1981!, and Hansen and Singleton ~1982, 1983! show how a simple relation between consumption and asset returns captures the implications of complex dynamic intertemporal multifactor asset pricing models. Unfortunately, consumption-based asset pricing models prove disappointing empirically. Hansen and Singleton ~1982, 1983! formulate a canonical consumption-based model in which a representative investor has timeseparable power utility of consumption. They reject the model on U.S. data, finding that it can not simultaneously explain the time-variation of interest rates and the cross-sectional pattern of average returns on stocks and bonds. Wheatley ~1988! rejects the model on international data. All models can be rejected, and the more important issue is which approximate models are most useful. Alas, the canonical consumption-based model performs no better, and in many respects worse, than even the simple static Capital Asset Pricing Model ~CAPM!. Mankiw and Shapiro ~1986! regress the average returns of the 464 NYSE stocks that were continuously traded from 1959 to 1982 on their market betas, on consumption growth betas, and on both betas. They find that market betas are more strongly and robustly
Management's Incentives to Avoid Negative Earnings Surprises

Recent reports in the business press allege that managers take actions to avoid negative earnings surprises. I hypothesize that certain firm characteristics are associated with greater incentives to avoid negative surprises. I find that firms with higher transient institutional ownership, greater reliance on implicit claims with their stakeholders, and higher value‐relevance of earnings are more likely to meet or exceed expectations at the earnings announcement. I also examine whether firms manage earnings upward or guide analysts' forecasts downward to avoid missing expectations at the earnings announcement. I examine the relation between firm characteristics and the probability (conditional on meeting analysts' expectations) of having (1) positive abnormal accruals, and (2) forecasts that are lower than expected (using a model of prior earnings changes). Overall, the results suggest that both mechanisms play a role in avoiding negative earnings surprises.
Toward a comprehensive developmental model for major depression in women.

OBJECTIVE: Major depression is a multifactorial disorder with many etiologic variables that are interrelated through developmental pathways. The authors used structural equation modeling to generate a developmental model for the etiology of major depression in women. METHOD: Data from 1,942 adult female twins, interviewed up to four times over a 9-year period, were used to construct a developmental model to predict depressive episodes in the year before the most recent interview. Eighteen risk factors in five developmental tiers were considered: 1) childhood (genetic risk, disturbed family environment, childhood sexual abuse, and childhood parental loss), 2) early adolescence (neuroticism, self-esteem, and early-onset anxiety and conduct disorder), 3) late adolescence (educational attainment, lifetime traumas, social support, and substance misuse), 4) adulthood (history of divorce and past history of major depression), and 5) the last year (marital problems, difficulties, and stressful life events). RESUL...
Foundational proof-carrying code

Proof-carrying code is a framework for the mechanical verification of safety properties of machine-language programs, but the problem arises of "quis custodiat ipsos custodes" - i.e. who verifies the verifier itself? Foundational proof-carrying code is verification from the smallest possible set of axioms, using the simplest possible verifier and the smallest possible runtime system. I describe many of the mathematical and engineering problems to be solved in the construction of a foundational proof-carrying code system.
What is the Rees algebra of a module

In this paper we show that the Rees algebra can be made into a functor on modules over a ring in a way that extends its classical definition for ideals. The Rees algebra of a module M may be computed in terms of a maximal map f from M to a free module as the image of the map induced by f on symmetric algebras. We show that the analytic spread and reductions of M can be determined from any embedding of M into a free module, and in characteristic 0-but not in positive characteristic!-the Rees algebra itself can be computed from any such embedding.
Direct numerical simulation of turbulent flow in a square duct

A direct numerical simulation of a fully developed, low-Reynolds-number turbulent flow in a square duct is presented. The numerical scheme employs a time-splitting method to integrate the three-dimensional, incompressible Navier-Stokes equations using spectral/high-order finite-difference discretization on a staggered mesh ; the nonlinear terms are represented by fifth-order upwind-biased finite differences. The unsteady flow field was simulated at a Reynolds number of 600 based on the mean friction velocity and the duct width, using 96 x 101 x 101 grid points. Turbulence statistics from the fully developed turbulent field are compared with existing experimental and numerical square duct data, providing good qualitative agreement. Results from the present study furnish the details of the corner effects and near-wall effects in this complex turbulent flow field; also included is a detailed description of the terms in the Reynolds-averaged streamwise momentum and vorticity equations. Mechanisms responsible for the generation of the stress-driven secondary flow are studied by quadrant analysis and by analysing the instantaneous turbulence structures. It is demonstrated that the mean secondary flow pattern, the distorted isotachs and the anisotropic Reynolds stress distribution can be explained by the preferred location of an ejection structure near the corner and the interaction between bursts from the two intersecting walls. Corner effects are also manifested in the behaviour of the pressure-strain and velocity-pressure gradient correlations.
Efficient Discovery of Association Rules and Frequent Itemsets through Sampling with Tight Performance Guarantees

The tasks of extracting (top-K) Frequent Itemsets (FIs) and Association Rules (ARs) are fundamental primitives in data mining and database applications. Exact algorithms for these problems exist and are widely used, but their running time is hindered by the need of scanning the entire dataset, possibly multiple times. High-quality approximations of FIs and ARs are sufficient for most practical uses. Sampling techniques can be used for fast discovery of approximate solutions, but works exploring this technique did not provide satisfactory performance guarantees on the quality of the approximation due to the difficulty of bounding the probability of under- or oversampling any one of an unknown number of frequent itemsets. We circumvent this issue by applying the statistical concept of Vapnik-Chervonenkis (VC) dimension to develop a novel technique for providing tight bounds on the sample size that guarantees approximation of the (top-K) FIs and ARs within user-specified parameters. The resulting sample size is linearly dependent on the VC-dimension of a range space associated with the dataset. We analyze the VC-dimension of this range space and show that it is upper bounded by an easy-to-compute characteristic quantity of the dataset, the d-index, namely, the maximum integer d such that the dataset contains at least d transactions of length at least d such that no one of them is a superset of or equal to another. We show that this bound is tight for a large class of datasets. The resulting sample size is a significant improvement over previous known results. We present an extensive experimental evaluation of our technique on real and artificial datasets, demonstrating the practicality of our methods, and showing that they achieve even higher quality approximations than what is guaranteed by the analysis.
On the Differences Between Scientific and Artistic Approaches to Qualitative Research

My intention in this paper is to identify 10 dimensions in which artistic and scientific approaches to qualitative research differ. The term qualitative research does not have a long history in the field of education and in many ways it not only hides the important distinctions which need to be made, but it is, itself, misleading. The major distinction we seek is not between qualitative and nonqualitative forms of research since all empirical research must of necessity pay attention to qualities, but between what is studied in a scientific mode and what is studied artistically. There can be no empirical research, that form of research that addresses problems in a material universe, that does not aim to describe, interpret, predict or control qualities. The major distinction to be made in the conduct of research is not located in the phenomenon of study but in the mode in which that study occurs. The difference that counts is between what is studied artistically and what is studied scientifically. These differences are the ones to which this paper is addressed. At the outset it should be said
Chiral polarization scale of QCD vacuum and spontaneous chiral symmetry breaking

It has recently been found that dynamics of pure glue QCD supports the low energy band of Dirac modes with local chiral properties qualitatively different from that of a bulk: while bulk modes suppress chirality relative to statistical independence between left and right, the band modes enhance it. The width of such chirally polarized zone – chiral polarization scale ∧ch – has been shown to be finite in the continuum limit at fixed physical volume. Here we present evidence that ∧ch remains non-zero also in the infinite volume, and is therefore a dynamical scale in the theory. Our experiments in Nf = 2+1 QCD support the proposition that the same holds in the massless limit, connecting ∧ch to spontaneous chiral symmetry breaking. In addition, our results suggest that thermal agitation in quenched QCD destroys both chiral polarization and condensation of Dirac modes at the same temperature Tch > Tc.
Speculations on the breakdown of scaling at 10 − 15 cm

We discuss the hypothesis that scaling in deep-inelastic electron-nucleon scattering is a "preasymptotic" phenomenon, which will be broken at energies large enough to probe the structure of the constituents of the nucleon. In particular, we consider a model in which the constituents are light (i.e., $M\ensuremath{\lesssim}{M}_{p}$) and are bound by a very heavy gluon (${M}_{G}\ensuremath{\gg}{M}_{p}$), which induces a small "size" in the constituents of order ${{M}_{G}}^{\ensuremath{-}1}$. The experimental implications of this hypothesis are discussed, primarily for the region of momentum transfers ${M}^{2}\ensuremath{\ll}{Q}^{2}\ensuremath{\ll}{{M}_{G}}^{2}$. In a bound-state model, using the Bethe-Salpeter equation in ladder approximation, we show that the deviations from simple scaling behavior in spacelike scattering and timelike annihilation processes are correlated and measure the "size" of the constituent. Finally, we show that the hypothesis that the constituent has structure is not inconsistent with local current algebra and, in particular the Adler sum rule for neutrino-nucleon scattering.
An Analysis of Latin American Peanut Trade

The U.S. export share in the world peanut market has decreased due to heavy competition. In this paper, the Latin American peanut industry is modeled using seemingly unrelated regression (SUR). Based on these estimations, a scenario analysis was conducted. The results show that the Latin American demand is not affected dramatically by either domestic or world price shocks. The effects of price changes on net trade are noticeable. However, the world price does not significantly affect the Latin American peanut supply. The results imply that Latin American peanut farmers are more sensitive to changes in domestic prices than world price changes.
How to make a DNA chip

Microarrays are one of the hottest areas in biological research today. Microarrays have been mostly applied to nucleic acid analysis, specifically to the assessment of which genes are being expressed and at what level. Early microarrays were prepared by using photolithographic methods, which were more commonly used for integrated circuit ("computer chip") production. Hence the colloquial term "DNA chip" came into being. The completion of the sequencing of the human genome and that of many other organisms makes the determination of gene function an important next step in understanding the role of DNA in the processes of life. DNA microarrays are an excellent tool to address this question because their numerous probe sites enable the analysis of many genes simultaneously. With good experience in this initial use, many further applications of microarrays are being developed, including genotyping in research and genetic diagnosis in medicine. DNA microarrays have made abundantly clear the power of vast parallelism in biological analysis, which is raising interest in other types of microarrays (small-molecule, protein). Many applications for DNA microarrays have been developed and clearly many more will emerge through the creativity of the scientists who use them. In early studies, users produced their own microarrays. The apparent power of microarrays has demanded improvements in production methods, and technologies from physical sciences and engineering are now being applied to DNA chips. Many branches of chemistry can contribute to improved methods: from synthetic chemistry (to attach or prepare DNA), to the physical chemistry of surfaces, to analytical chemistry (to assess surface reactions).
The ECL programming system

ECL is a programming language system currently being implemented as a research project at Harvard University. Its goal is an environment which will significantly facilitate the production of programs. In this paper, we describe the motivation for this project, present the approach taken in its design, and sketch the resulting ECL system. Detailed treatment of specific aspects of the system are found elsewhere.
Distributed Beamforming in Wireless Multiuser Relay-Interference Networks With Quantized Feedback

We study fixed data rate communication schemes for wireless relay-interference networks with any number of transmitters, relays, and receivers. The transmitters and the relays have individual short-term power constraints. We analyze both amplify- and-forward (AF) and decode-and-forward (DF) relaying strategies with a two channel use quantized network beamforming protocol. We design the quantizer of the channel state information to minimize the probability that at least one receiver incorrectly decodes its desired symbol(s). Correspondingly, we introduce a generalized diversity measure that encapsulates the conventional one as the first-order diversity. Additionally, it incorporates the second-order diversity, which is concerned with the transmitter power dependent logarithmic terms that appear in the error rate expression. We first show that for AF relays, the maximal achievable diversity in the presence of interference is strictly less than the transmit diversity bound in terms of the second-order diversity. We then prove that it is possible to achieve the transmit diversity bound using DF relays as if there is no interference and as if coding over an arbitrary number of channel uses is allowed. Relay selection provides the best possible diversity gain for both relaying strategies. Finally, we show that all the aforementioned diversity gains can be achieved using distributed decision making with asymptotically zero feedback rate per receiver. Such a performance is made possible by a special distributed quantizer design method we have called localization.
The role of environment in the mass–metallicity relation

Using a sample of 57 377 star-forming galaxies drawn from the Sloan Digital Sky Survey, we study the relationship between gas-phase oxygen abundance and environment in the local Universe. We find that there is a strong relationship between metallicity and environment such that more metal-rich galaxies favour regions of higher overdensity. Furthermore, this metallicity–density relation is comparable in strength to the colour–density relation along the blue cloud. After removing the mean dependence of environment on colour and luminosity, we find a weak, though significant, residual trend between metallicity and environment which is largely driven by galaxies in high-density regions, such as groups and clusters. We discuss the potential source of this relationship between metallicity and local galaxy density in the context of feedback models, with special attention paid to quantifying the impact of environment on the scatter in the mass–metallicity relation. We find that environment is a non-negligible source of scatter in this fundamental relation, with 15 per cent of the measured scatter correlated with environment.
Analysis of high DC current gain structures for GaN/InGaN/GaN HBTs

AlGaN/GaN HBTs with DC current gains in excess of 10 have been demonstrated; however, Makimoto et al. have recently obtained a DC current gain value exceeding 2000 for a GaN/InGaN/GaN triple mesa DHBT. The experimental demonstration of a GaN-based HBT with such extraordinary DC current gain has motivated the search for new device structures conducive to high DC current gain. Simulations in this work indicate that high DC current gain is difficult to achieve with a uniform, defect-free base layer. We also simulate the electrical characteristics of a new class of DHBT where the base layer is non-uniform. By non-uniformly thinning or perforating the base, the majority of the base would remain thick to minimize the negative impact to base resistance. However, small thinned regions achieve extremely high DC current gain, which can be used to significantly increase the overall DC current gain. This device structure could naturally occur when "V" defects form or indium is non-uniformly distributed during the base layer growth. The sensitivity of DC current gain to the base thickness range, duty cycle, defect geometry, and defect type is also investigated.
Do Political Parties Matter? Evidence from U.S. Cities

Are cities as politically polarized as states and countries? “No” is the answer from our regression discontinuity design analysis, which shows that whether the mayor is a Democrat or a Republican does not affect the size of city government, the allocation of local public spending, or crime rates. However, there is a substantial incumbent effect for mayors. We investigate three mechanisms that could account for the striking lack of partisan impact at the local level, and find the most support for Tiebout competition among localities within metropolitan areas.
Thue systems as rewriting systems

This paper is a survey of recent results on Thue systems, where the systems are viewed as rewriting systems on strings over a finite alphabet. The emphasis is on Thue systems with the Church-Rosser property, where the notion of reduction is based on length-decreasing rewriting rules. The main effort is expended in outlining the properties of such systems, paying close attention to the issue of the possible decidability of properties and to the issue of the computational complexity of decidable properties. Since Thue systems may also be considered as presentations of monoids, the language of monoids (and groups) is used to describe some of these properties.
Folding, aggregation and molecular recognition in peptides

In past years, most of the X-ray structure determinations of oligopeptides were for cyclic peptides or for short linear peptides. Longer peptides usually presented many difficulties in obtaining suitable crystals since the molecules are intrinsically very flexible. More recently, it has been appreciated that the aminoisobutyric acid residue (Aib), which occurs naturally in many peptides of microbial origin, initiates helix folding. Several score of 7- to 15-residue linear peptides containing Aib have been synthesized, crystallized and had their structures determined to high resolution. Many of the peptide structures have been determined in more than one crystalline form. These peptide structures have yielded a plethora of information on types of helices, modes of hydration, water penetration into helical backbones, helices bent by Pro residues, parallel and antiparallel association of helices, effects of Leu residues on association of peptides, an example of a zipper assembly by side chains, and an example of a possible ion channel with a gating mechanism.
Preemptive Spacing With Vertical Differentiation When Input Quality is of Inelastic Supply

This paper examines a model of vertical differentiation in which an incumbent engages in preemptive spacing to prevent entry. Input quality is of fixed supply, and the incumbent prevents high-end entry by producing a product with all the quality available. It also commits to the production of a minimum-quality product to deter low-end entry. There is no entry in equilibrium, and the incumbent monopolist chooses to sell only its high-quality product. Commitment to the production of the minimum-quality product is used merely as a credible threat to vigorously compete should an entrant also produce a minimum-quality product.
Direct derivative measurements in the presence of sting plunging

This paper presents a review and extension of methods for determining the effects of sting oscillation on the measurement of dynamic derivatives due to oscillatory pitching. It is shown that two of the methods based on linear models will reduce to the same result, applicable to low-lift configurations. The location of the effective axis of rotation is determined for a model executing planar oscillations in two degrees of freedom. The equations for the effect of plunging on the derivatives can be simplified by relating the sting deflection parameters to the coordinate of this axis. The implications for analysis of sting plunging oscillation in dynamic tests of aircraft models at high angles of attack are also discussed. The effective rotation center could be determined by a simple method, and the associated effects evaluated, in pitch-oscilla tion tests of the Standard Dynamics Model at angles up to 45 deg. The axis shift was found to produce the main effect on the measured data.
Network Cost-Sharing without Anonymity

We consider network cost-sharing games with nonanonymous cost functions, where the cost of each edge is a submodular function of its users, and this cost is shared using the Shapley value. Nonanonymous cost functions model asymmetries between the players, which can arise from different bandwidth requirements, durations of use, services needed, and so on.These games can possess multiple Nash equilibria of wildly varying quality. The goal of this article is to identify well-motivated equilibrium refinements that admit good worst-case approximation bounds. Our primary results are tight bounds on the cost of strong Nash equilibria and potential function minimizers in network cost-sharing games with nonanonymous cost functions, parameterized by the set C of allowable submodular cost functions.These two worst-case bounds coincide for every set C, and equal the summability parameter introduced in Roughgarden and Sundararajan [2009] to characterize efficiency loss in a family of cost-sharing mechanisms. Thus, a single parameter simultaneously governs the worst-case inefficiency of network cost-sharing games (in two incomparable senses) and cost-sharing mechanisms. This parameter is always at most the kth Harmonic number Hk t ln k, where k is the number of players, and is constant for many function classes of interest.
Anxiety Management Training

This article provides detailed information on anxiety management training, a relaxation-based, self-control therapy for the treatment of generalized anxiety, phobias, anger, and other stress-related disorders. The article describes in detail the specific procedures of anxiety management training to enable the reader to utilize it with individuals and groups. Additionally, research findings are summarized, and the means for deciding on the proper use of anxiety management training are outlined. The article is coauthored by the developer of the technique and a leading researcher in its applications.
Housing First for Homeless Persons with Active Addiction: Are We Overreaching?

Context: More than 350 communities in the United States have committed to ending chronic homelessness. One nationally prominent approach, Housing First, offers early access to permanent housing without requiring completion of treatment or, for clients with addiction, proof of sobriety. Methods: This article reviews studies of Housing First and more traditional rehabilitative (e.g., “linear”) recovery interventions, focusing on the outcomes obtained by both approaches for homeless individuals with addictive disorders. Findings: According to reviews of comparative trials and case series reports, Housing First reports document excellent housing retention, despite the limited amount of data pertaining to homeless clients with active and severe addiction. Several linear programs cite reductions in addiction severity but have shortcomings in long-term housing success and retention. Conclusions: This article suggests that the current research data are not sufficient to identify an optimal housing and rehabilitation approach for an important homeless subgroup. The research regarding Housing First and linear approaches can be strengthened in several ways, and policymakers should be cautious about generalizing the results of available Housing First studies to persons with active addiction when they enter housing programs.
COSMOLOGICAL SIMULATIONS OF ISOTROPIC CONDUCTION IN GALAXY CLUSTERS

Simulations of galaxy clusters have a difficult time reproducing the radial gas-property gradients and red central galaxies observed to exist in the cores of galaxy clusters. Thermal conduction has been suggested as a mechanism that can help bring simulations of cluster cores into better alignment with observations by stabilizing the feedback processes that regulate gas cooling, but this idea has not yet been well tested with cosmological numerical simulations. Here we present cosmological simulations of 10 galaxy clusters performed with five different levels of isotropic Spitzer conduction, which alters both the cores and outskirts of clusters, though not dramatically. In the cores, conduction flattens central temperature gradients, making them nearly isothermal and slightly lowering the central density, but failing to prevent a cooling catastrophe there. Conduction has little effect on temperature gradients outside of cluster cores because outward conductive heat flow tends to inflate the outer parts of the intracluster medium (ICM), instead of raising its temperature. In general, conduction tends reduce temperature inhomogeneity in the ICM, but our simulations indicate that those homogenizing effects would be extremely difficult to observe in ~5?keV clusters. Outside the virial radius, our conduction implementation lowers the gas densities and temperatures because it reduces the Mach numbers of accretion shocks. We conclude that, despite the numerous small ways in which conduction alters the structure of galaxy clusters, none of these effects are significant enough to make the efficiency of conduction easily measurable, unless its effects are more pronounced in clusters hotter than those we have simulated.