cssi/SciSciGPT-SciSciNet huggingface dataset:
Properties of Peach Flower Buds Which Facilitate Supercooling

Water in dormant peach ( Prunus persica [L.] Batsch. var. `Harbrite9) flower buds deep supercooled. Both supercooling and the freezing of water within the bud axis and primordium as distinct components depended on the viability of the bud axis tissue. The viability of the primordium was not critical. Supercooling was prevented by wounding buds with a dissecting needle, indicating that bud structural features were important. Bud morphological features appeared to prevent the propagation of ice through the vascular tissue and into the primordium. In dormant buds, procambial cells had not yet differentiated into xylem vessel elements. Xylem continuity between the bud primordium and adjacent tissues did not appear to be established until buds had deacclimated. It was concluded that structural, morphological, and physiological features of the bud facilitated supercooling.
Grassmannian and string theory.

The infinite-dimensional Grassmannian manifold contains moduli spaces of Riemann surfaces of all genera. This well known fact leads to a conjecture that non-perturbative string theory can be formulated in terms of the Grassmannian. We present new facts supporting this hypothesis. In particular, it is shown that Grassmannians can be considered as generalized moduli spaces; this statement permits us to define corresponding “string amplitudes” (at least formally). One can conjecture that it is possible to explain the relation between non-perturbative and perturbative string theory by means of localization theorems for equivariant cohomology; this conjecture is based on the characterization of moduli spaces, relevant to string theory, as sets consisting of points with large stabilizers in certain groups acting on the Grassmannian. We describe an involution on the Grassmannian that could be related to S-duality in string theory.
Technical speech: A need for teaching and research

Recent questionnaire surveys of on-the-job engineers indicate that they want training in technical speech. The author suggests that courses in technical speech might be improved if teachers knew more about how technical speech differs from other kinds of speech, and more about the requirements for successful technical speaking. Research into matters of audience, delivery, and audiovisual aids can help to provide this needed information.
Optimum structural sizing for gust induced response

The present paper describes an optimization capability for sizing airframe structures that are subjected to a combination of deterministic and random loads. Design constraints are implemented to prevent structural failure in fatigue and due to a single exceedance of the allowable stress. The random load is treated as a stationary, homogeneous process with a Gaussian probability distribution, and a frequency domain method is used for the computation of dynamic response parameters. An equal-probability-of-load-combination criterion is proposed in the formulation of strength constraints. This alleviates problems associated with the incomplete phase information available when using power spectral density methods. The optimization procedure is illustrated by examples using typical built-up structures.
Can the Electroweak Symmetry-breaking Sector Be Hidden?

Abstract In a recent paper, Chivukula and Golden claimed that the electroweak symmetry-breaking sector could be hidden if there were many inelastic channels in the longitudinal WW scattering process. They presented a model in which the W's couple to pseudo-Goldstone bosons, which may be difficult to detect experimentally. Because of these inelastic channels, thw WW interactions do not become strong in the TeV region. We demonstrate that, despite the reduced WW elastic amplitudes in this model, the total event rate (∼ 5000 extra longitudinal W + W − pairs produced in one standard SSC year) does not decrease with an increasing number of inelastic channels, and is roughly the same as in a model with a broad high-energy resonance and no inelastic channels.
A Domino Copper-Catalyzed C−O Coupling−Claisen Rearrangement Process

A practical method for the diastereoselective generation of two adjacent quarternary stereocenters by combining a copper-catalyzed C−O coupling reaction with a subsequent Claisen rearrangement in a one-pot domino process is described. Furthermore, an experimentally simple method for the stereoselective synthesis of a variety of different types of vinyl ethers is delineated using the same catalyst system.
DIELS-ALDER CHEMISTRY OF A 2,4-DIOXYGENATED FURAN

Abstract The preparation of a 2,4-dioxygenated furan, 1, is reported. Its Diels-Alder reactivity with dienophiles is detailed.
Supercharges, Killing spinors and intersecting gauge five-branes

Abstract We obtain new solutions where a string and a pp-wave lie in the common world-volume directions of the non-standard intersection of two gauge 5-branes in the heterotic string. The two 5-branes are supported by independent SU (2) Yang–Mills instantons in their respective (non-overlapping) transverse spaces. We present a detailed study of the unbroken supersymmetry, focusing especially on a comparison between a direct construction of Killing spinors and a counting of zero eigenvalues in the anticommutator of supercharges. The results are in agreement with some previous arguments, to the effect that additional zero eigenvalues resulting from a “fine-tuning” between positive-energy and negative-energy contributions from different components in an intersection are spurious, and should not be taken as an indication of supersymmetry enhancements. These observations have a general applicability that goes beyond the specific example we study in this paper.
Mathematical modelling for the capacity planning of market oriented systems: with an application to real health data

Abstract This paper presents mathematical modelling for the prediction of patient/client/customer “flows” within a large geographical domain. The modelling also accounts for differing levels of aggregation of the origin and destination zones, referral patterns, and various scenarios of closure, expansion, contraction, and merger of facilities. Some results of applications of the modelling to capacity planning are presented for a data base aggregated for the acute care facilities within the state of Massachusetts.
Steric sea level change in the northern seas

Abstract Ocean temperature and salinity data over the period 1950–2000 in the Northern Seas, defined here as the North Atlantic Ocean (north of 50°N), North Pacific Ocean (north of 40°N), and Arctic Oceans, are combined to diagnose the steric (i.e., density) contribution to sea level variation. The individual contributions to steric height from temperature (thermosteric height) and salinity (halosteric height) are also analyzed. It is found that during 1950–2000, steric height rose over the study’s domain, mostly as a result of halosteric increases (i.e., freshening). Over a shorter time period (late 1960s to early 1990s) during which climate indices changed dramatically, steric height gradients near the Nordic Seas minimum were reduced by 18%–32%. It is speculated that this may be associated with a local slowing of both the Meridional Overturning Circulation and the southward flow through Fram Strait. However, steric height increases in the North Pacific Ocean during this time imply a possible accelerati...
Temperature-Dependent Reflectance of Plated Metals and Composite Materials Under Laser Irradiation

Experiments were performed to investigate laser-heating-induced changes in the surface properties of metals and composite structural materials commonly used in aerospace applications. The objective of this test series was to determine the effect of surface heating on the 1.3-μm-wavelength laser reflectance of these materials. Reflectance measurements were made using a unique hemiellipsoidal reflectometer. Polished metals, plated metals, and composite materials were tested to determine their temperature-dependent reflectance characteristics in vacuum and air environments. This experiment series produced temperature-dependent, 1.3-μm laser reflectance curves for use in surface degradation analyses. All of the finishes investigated on duplex stainless-steel substrates increase the low-temperature, 1.3-μm reflectance compared to the unpolished steel. However, the reflectance decreases dramatically at elevated temperatures when the surfaces discolor. The large reflectance transition observed for the polished and plated steel coupons in air also occur in vacuum. The polished aluminum alloys had a higher 1.3-μm reflectance than the plated aluminum samples throughout the temperature range. The elevated temperature reflectance of S-glass epoxy is irradiance dependent. Low irradiance creates a black char. A higher irradiance can ignite the char and form a lighter, more reflective surface.
Growth of Rank 1 Valuation Semigroups

We consider semigroup S of a rank 1 valuation ? centered on a local ring R. We show that the Hilbert polynomial of R gives a bound on the growth of the valuation semigroup S. This allows us to give a very simple example of a well ordered subsemigroup of Q+, which is not a value semigroup of a local domain. We also consider the rates of growth which are possible for S. We show that quite exotic behavior can occur. In the final section, we consider the general question of characterizing rank 1 value semigroups.
Special values of trigonometric Dirichlet series and Eichler integrals

We provide a general theorem for evaluating trigonometric Dirichlet series of the form $$\sum _{n \geqslant 1} \frac{f (\pi n \tau )}{n^s}$$ , where f is an arbitrary product of the elementary trigonometric functions, $$\tau $$ a real quadratic irrationality and s an integer of the appropriate parity. This unifies a number of evaluations considered by many authors, including Lerch, Ramanujan and Berndt. Our approach is based on relating the series to combinations of derivatives of Eichler integrals and polylogarithms.
Key Generation Using External Source Excitation: Capacity, Reliability, and Secrecy Exponent

We study the fundamental limits to secret key generation from an excited distributed source (EDS). In an EDS, a pair of terminals observe dependent sources of randomness excited by a pre-arranged signal. We first determine the secret key capacity for such systems with one-way public messaging. We then characterize a tradeoff between the secret key rate and exponential bounds on the probability of key agreement failure and on the secrecy of the key generated. We find that there is a fundamental tradeoff between reliability and secrecy. We then explore this framework within the context of reciprocal wireless channels. In this setting, the users transmit pre-arranged excitation signals to each other. When the fading is Rayleigh, the observations of the users are jointly Gaussian sources. We show that an on-off excitation signal with an signal-to-noise ratio (SNR)-dependent duty cycle achieves the secret key capacity of this system. Furthermore, we characterize a fundamental metric - minimum energy per key bit for reliable key generation - and show that in contrast to conventional AWGN channels, there is a nonzero threshold SNR that achieves the minimum energy per key bit. The capacity achieving on-off excitation signal achieves the minimum energy per key bit at any SNR below the threshold. Finally, we build off our error exponent results to investigate the energy required to generate a key using a finite block length. Again we find that on-off excitation signals yield an improvement when compared to constant excitation signals. In addition to Rayleigh fading, we analyze the performance of a system based on binary channel phase quantization.
Estimating Missing Values from the General Social Survey: An Application of Multiple Imputation

Objectives. Most researchers who use survey data must grapple with the problem of how best to handle missing information. This article illustrates multiple imputation, a technique for estimating missing values in a multivariate setting. Methods. I use multiple imputation to estimate missing income data and update a recent study that examines the influence of parents’ standard of living on subjective well-being. Using data from the 1998 General Social Survey, two ordered probit models are estimated; one using complete cases only, and the other replacing missing income data with multiple imputation estimates. Results. The analysis produces two major findings: 1) parents’ standard of living is more important than suggested by the complete cases model, and 2) using multiple imputation can help to reduce standard errors. Conclusions. Multiple imputation allows a researcher to use more of the available data, thereby reducing biases that may occur when observations with missing data are simply deleted.
Whither correlated electron theory

Abstract This is the text of the ‘Theory’ opening talk at the 2001 Strongly Correlated Electron Systems conference. It contains opinions about some of the outstanding scientific challenges facing the theory side of the correlated electrons field.
Cosmology with the Sunyaev-Zel'dovich Effect

▪ Abstract The Sunyaev-Zel'dovich effect (SZE) provides a unique way to map the large-scale structure of the universe as traced by massive clusters of galaxies. As a spectral distortion of the cosmic microwave background, the SZE is insensitive to the redshift of the galaxy cluster, making it well-suited for studies of clusters at all redshifts, and especially at reasonably high redshifts (z > 1) where the abundance of clusters is critically dependent on the underlying cosmology. Recent high signal-to-noise detections of the SZE have enabled interesting constraints on the Hubble constant and on the matter density of the universe using small samples of galaxy clusters. Upcoming SZE surveys are expected to find hundreds to thousands of new galaxy clusters, with a mass selection function that is remarkably uniform with redshift. In this review we provide an overview of the SZE and its use for cosmological studies, with emphasis on the cosmology that can, in principle, be extracted from SZE survey yields. We ...
A Consistent Quantum Ontology

Abstract The (consistent or decoherent) histories interpretation provides a consistent realistic ontology for quantum mechanics, based on two main ideas. First, a logic (system of reasoning) is employed which is compatible with the Hilbert-space structure of quantum mechanics as understood by von Neumann: quantum properties and their negations correspond to subspaces and their orthogonal complements. It employs a special (single framework) syntactical rule to construct meaningful quantum expressions, quite different from the quantum logic of Birkhoff and von Neumann. Second, quantum time development is treated as an inherently stochastic process under all circumstances, not just when measurements take place. The time-dependent Schrodinger equation provides probabilities, not a deterministic time development of the world. The resulting interpretive framework has no measurement problem and can be used to analyze in quantum terms what is going on before, after, and during physical preparation and measurement processes. In particular, appropriate measurements can reveal quantum properties possessed by the measured system before the measurement took place. There are no mysterious superluminal influences: quantum systems satisfy an appropriate form of Einstein locality. This ontology provides a satisfactory foundation for quantum information theory, since it supplies definite answers as to what the information is about. The formalism of classical (Shannon) information theory applies without change in suitable quantum contexts, and this suggests the way in which quantum information theory extends beyond its classical counterpart.
Divorce and the cognitive achievement of children

Children of divorced parents exhibit lower test scores and educational attainment. Have these correlations a causal interpretation? Parents who divorce may be less likely to invest in their children while together or they may divorce to shield their children from the effects of marital conflict. I study the relationship between children's achievement and the marital status of their parents within a dynamic framework in which partners decide on whether to remain married, how to interact (with or without conflict), and child investments. I then assess whether a child whose parents divorced would have been better off had divorce not occurred.
Experimental test of the Rayleigh-Debye-Gans theory for light scattering by fractal aggregates.

Calibrated measurements of optical (λ = 488-nm) scattering cross sections, in the form of Rayleigh ratios, are presented for two fractal aggregate aerosols. The aggregates have radii of gyration of approximately 280 nm, fractal dimensions of approximately 1.75, and monomer sizes of approximately 20 nm with approximately 150 monomers per cluster. One aerosol was composed of vitreous SiO2 with a refractive index of 1.46, the other of anatase TiO2 with a refractive index of 2.61. We found good agreement with the Rayleigh-Debye-Gans prediction for the scattering cross section of fractal aggregates.
Regularity and Blow up for Active Scalars

We review some recent results for a class of fluid mechanics equations called active scalars, with fractional dissipation. Our main examples are the surface quasi-geostrophic equation, the Burgers equation, and the Cordoba-Cordoba-Fontelos model. We discuss nonlocal maximum principle methods which allow to prove existence of global regular solutions for the critical dissi- pation. We also recall what is known about the possibility of finite time blow up in the supercritical regime.
AN ORIENTIFOLD OF TYPE-IIB THEORY ON K3

Abstract A new orientifold of Type-IIB theory on K3 is constructed that has N =1 supersymmetry in six dimensions. The orientifold symmetry consists ofaa |Z 2 involution of K3 combined with orientation reversal on the world-sheet. The closed-string sector in the resulting theory contains nine tensor multiplets and twelve neutral hypermultiplets in addition to the gravity multiplet, and is anomaly free by itself. The open-string sector contains only five-branes and gives rise to maximal gauge groups SO (16) or U (8) × U (8) at different points in the moduli space. Anomalies are canceled by a generalization of the Green-Schwarz mechanism that involves more than one tensor multiplets.
Formation of the first stars.

Understanding the formation of the first stars is one of the frontier topics in modern astrophysics and cosmology. Their emergence signalled the end of the cosmic dark ages, a few hundred million years after the Big Bang, leading to a fundamental transformation of the early Universe through the production of ionizing photons and the initial enrichment with heavy chemical elements. We here review the state of our knowledge, separating the well understood elements of our emerging picture from those where more work is required. Primordial star formation is unique in that its initial conditions can be directly inferred from the Λ cold dark matter (ΛCDM) model of cosmological structure formation. Combined with gas cooling that is mediated via molecular hydrogen, one can robustly identify the regions of primordial star formation, the so-called minihalos, having total masses of ~106 M⊙ and collapsing at redshifts z 20–30. Within this framework, a number of studies have defined a preliminary standard model, with the main result that the first stars were predominantly massive. This model has recently been modified to include a ubiquitous mode of fragmentation in the protostellar disks, such that the typical outcome of primordial star formation may be the formation of a binary or small multiple stellar system. We will also discuss extensions to this standard picture due to the presence of dynamically significant magnetic fields, of heating from self-annihalating WIMP dark matter, or cosmic rays. We conclude by discussing possible strategies to empirically test our theoretical models. Foremost among them are predictions for the upcoming James Webb space telescope (JWST), to be launched ~2018, and for 'stellar archaeology', which probes the abundance pattern in the oldest, most-metal poor stars in our cosmic neighborhood, thereby constraining the nucleosynthesis inside the first supernovae.
WAPTT/AMFORT Congress

The ninth Congress and the General Assembly of the World Association for Professional Training in Tourism (WAPTT or AMFORT in French and Spanish) was held in Havana, Cuba, November 19-23, 1990. The theme of the conference was Tourism and Development: Tourism in Latin America Facing the Challenge of Year 2000. The Congress was opened by LOY PUDDU, WAPTT President, who was joined by representatives from the host government and other organizational bodies, welcoming the Congress and speaking on the significance of the theme. For the treatment of the theme, four commissions were formed: Economic Aspects of Tourism Development; Links Among the Enterprises, Public Agencies and Schools in Training Tourism Personnel; Sociocultural Aspects of Tourism Development ; and Pedagogical Aspects of Training Tourism Personnel. Each commission had successive sessions at which numerous paper presentations were made. Communication among Congress participants was facilitated with simultaneous interpretation in English, French, and Spanish. The Congress succeeded in bringing into focus a large number of interrelated issues or perspectives, a fragmented sample of which would perhaps give an indication of their nature and orientation. Throughout the conference, there were many occasions to elaborate on the significance of tourism : dtourism has become one of the most important activities of our times.d References to the economic prospects of tourism were many: dits multiple forms of income and employment.d But it was acknowledged that potentials for tourism development dmust be evaluated with the prudence and realism that its particular characteristics demand,d and attempts should be made, at all times, to preventda widening difference between certain developed areas and developed countries,d that tourism cannot be d allowed to develop in an irreversible manner.... d Such potentially negative aspects or potentials of tourism were, however, not considered dinsurmountabled and the dnegative models ... can be neutralized... through planning.d To move in this direction, the dtourist sector should be managed by true specialists at all levels in order to
A PARALLEL ARCHITECTURE FOR AI NONLINEAR PLANNING

This paper presents a resource-level conflict detection and conflict resolution scheme which is combined with a state-level backward planning algorithm and provides efficient conflict detection and global conflict resolution for nonlinear planning. The scheme keeps track of the usage of individual resources during planning, and constructs a Resource-Usage Flow (RUF) structure (based on which conflict detection and resolution is accomplished). The RUF structure allows the system to perform minimal and nonredundant operations for conflict detection and resolution. Furthermore, resource-level conflict detection and resolution facilitates problem decomposition in terms of resources, thereby providing easy implementation in a parallel and distributed processing environment. Performance analysis indicates that the proposed architecture has a speed-up factor of the average depth of a plan network, D(Na), compared to the distributed NOAH, where Na (the total number of action nodes at the completion of planning) and D(Na) are considerably larger than the number of resources involved in planning as well as the number of initial goal states.
Fixed memory filter for real-time estimation of noise-corrupted signals

Introduction I N many engineering applications, such as guidance and navigation of aeronautical vehicles, the signals need to be estimated from noisy measurements in real time. The (minimum-variance) Kalman-Bucy filter' that relies on a finite-dimensional state-space model of the plant dynamics and the measurement history is extensively used for this purpose. Techniques of adaptive filtering' that are based on the principle of recursive least squares algorithm and rely on an inputoutput relationship of the plant dynamics are also used. Given a linear (or linearized) time-invariant finite-dimensional model of plant dynamics in the autoregressive moving average (ARMA) setting, we propose a fixed-memory, nonrecursive filter for real-time signal estimation. The key idea is to construct a simple, nonrecursive filter based on weighted averaging of a finite array of past values of measured inputs and outputs of the plant. A fixed memory filter is very useful in the applications of smart sensors and/or active sensors where memory constraints are tight and computationally efficient algorithms are required for real-time implementation on a microchip collocated with the sensor. The filter memory length depends on the plant dynamics and the allowable bound of estimation error and, for real-time applications, is often selected as a tradeoff between execution time and accuracy of the filter. This Engineering Note presents the concept and formulation of a fixed-memory filter based on an ARMA model of plant dynamics. The criteria for selection of the filter memory length are not included in this Note. Although the filter algorithm is derived for single-input single-output (SISO) systems, the proposed filter can be extended to multi-input multioutput (MIMO) systems.
Carbohydrate recognition by boronolectins, small molecules, and lectins

Carbohydrates are known to mediate a large number of biological and pathological events. Small and macromolecules capable of carbohydrate recognition have great potentials as research tools, diagnostics, vectors for targeted delivery of therapeutic and imaging agents, and therapeutic agents. However, this potential is far from being realized. One key issue is the difficulty in the development of "binders" capable of specific recognition of carbohydrates of biological relevance. This review discusses systematically the general approaches that are available in developing carbohydrate sensors and "binders/receptors," and their applications. The focus is on discoveries during the last 5 years.
Preservation of layered paleodeposits in high-latitude pedestal craters on Mars

An outstanding question in Mars’ climate history is whether or not pedestal craters represent the armored remnants of ice-rich paleodeposits. We address this question using new high-resolution images; in a survey of several hundred high-latitude pedestal craters, we have identified 12 examples in which visible and/or topographically expressed layers are exposed on the marginal scarp of the pedestal. One example, located on the south polar layered deposits, preserves ice-rich layers that have otherwise been completely removed from the polar cap. These observations provide empirical evidence that the pedestal crater formation mechanism is capable of armoring and preserving ice-rich layered paleodeposits. Although layered exposures have not yet been observed in mid-latitude pedestal craters, high-latitude instances of discontinuous, partially covered layers suggest that layers can be readily concealed, likely through mantling and/or mass wasting processes along the marginal scarp. This interpretation is supported by the observation that high-latitude pedestals with exposed layers along their margins are, on average, taller than mid-latitude examples, and have larger, steeper marginal scarps, which may help to maintain layer exposures. These observations favor the interpretation that mid- to high-latitude pedestal craters represent the armored remnants of ice- and dust-rich paleodeposits, which occurred transiently due to changes in the climate regime. Preservation of fine-scale layering of ice and dust at these latitudes implies that the climate change did not involve regional melting conditions.
Liquid chromatographic analysis and characterization of inorganic nanoclusters

Abstract We describe the application of the techniques of high pressure liquid chromatography (HPLC) to analyze and characterize various types of inorganic nanoclusters. Both metal and semiconductor nanoclusters were grown in inverse micelles and we demonstrate how the nanoclusters can be separated from the surfactants and other byproducts of the reaction by using a variety of HPLC columns. We also discuss passivation of the cluster surface to prevent aggregation. The HPLC columns separate the clusters based upon a combination of size exclusion and chemical affinity mechanisms and the optical properties of the purified clusters are determined on-line using a variety of detectors. These include a photodiode array for collecting absorbance spectra, a fluorescence detector to monitor luminescence, and a conductivity detector to monitor surface charge on the nanoclusters. We illustrate the analysis of nanoclusters using HPLC by showing data from semiconductor Si, MoS 2 nanoclusters and Au nanoclusters. An extremely novel luminescence was observed from very small metal nanoclusters.
The nil Hecke ring and singularity of Schubert varieties.

Let G be a semi-simple simply-connected complex algebraic group and T ⊂ B a maximal torus and a Borel subgroup respectively. Let ŋ= Lie T be the Cartan subalgebra of the Lie algebra Lie G, and W:= N(T)/T the Weyl group associated to the pair (G, T), where N(T) is the normalizer of T in G. We can view any element \( \omega = \overline \omega \) mod T I W as the element (denoted by the corresponding German character) xo of G/B, denned as \( m = \overline \omega B \). For any w I W, there is associated the Schubert variety \( {{\rm X}_{\omega }}: = \overline {B\omega B/B} \subset G/B \) and the T-fixed points of X w (under the canonical left action) are precisely \( {\rm I}\omega : = \left\{ {o:\upsilon \in Wand\upsilon \leqslant \omega } \right\} \).
A new small nano-Kelvin resolution thermometer for low-temperature experiments

A small, high-resolution paramagnetic susceptibility thermometer was developed using a GdCl/sub 3/ paramagnetic salt. The device uses a superconducting quantum interference device (SQUID) magnetometer to determine the temperature dependent magnetization of the salt in a magnetic field. The magnetic field is provided by a pair of small samarium cobalt permanent magnet disks situated inside the thermometer housing. This eliminates the need for a heavy, charging solenoid used in a conventional SQUID-based magnetic thermometer system. This thermometer can resolve approximately 10/sup -9/ K near the liquid-gas critical point of /sup 3/He (/spl sim/3.31 K). The drift rate of the thermometer was measured to be <2/spl times/10/sup -13/ K/s. This light weight thermometer (/spl sim/7 g) is a candidate for use in future low-temperature Space Shuttle and International Space Station experiments.
An Analysis Methodology for Internal Swirling Flow Systems With a Rotating Wall

We present an analysis methodology for the calculation of the flow through internal flow components with a rotating wall such as annular seals, impeller cavities, and enclosed rotating disks. These flow systems are standard components in gas turbines and cryogenic engines and are characterized by subsonic viscous flow and elliptic pressure effects. The Reynolds-averaged Navier-Stokes equations for turbulent flow are used to model swirling axisymmetric flow
Stochastic Humanitarian Inventory Control Model for Disaster Planning

The impacts of disasters have recently attracted increased attention from researchers and policy makers. However, there has been little consensus about how an efficient inventory management model can be developed for postdisaster conditions. Victims of a disaster are generally gathered into shelters during and after a severe disaster to ensure their security. Many evacuees do not have the financial resources to leave the disaster area or to find food, drugs, and other necessities. Hence, their vital needs should be supplied efficiently throughout the disaster and postdisaster periods. Without an adequate stock of goods, satisfying the daily requirements of the victims without disruption might be problematic. To solve this problem, humanitarian inventory control models that can aid in adequately responding to a disaster or a humanitarian crisis are needed. In this context, response represents preparedness, planning, assessment, appeal, mobilization, procurement, transportation, warehousing, and distributio...
Pedagogical agent design: The impact of agent realism, gender, ethnicity, and instructional role

In the first of two experimental studies, 312 students were randomly assigned to one of 8 conditions, where agents differed by ethnicity (Black, White), gender (male, female), and image (realistic, cartoon), yet had identical messages and computer-generated voice. In the second study, 229 students were randomly assigned to one of 12 conditions where agents represented different instructional roles (expert, motivator, and mentor), also differing by ethnicity (Black, White), and gender (male, female). Overall, it was found that students had greater transfer of learning when the agents had more realistic images and when agents in the “expert” role were represented non-traditionally (as Black versus White). Results also generally confirmed prior research where agents perceived as less intelligent lead to significantly improved self-efficacy. The presence of motivational messages, as employed through the motivator and mentor agent roles, led to enhanced learner self-regulation and self-efficacy. Results are discussed with respect to social cognitive theory.
Root systems for asymmetric geometric representations of Coxeter groups

Results are obtained concerning root systems for asymmetric geometric representations of Coxeter groups. These representations were independently introduced by Vinberg and Eriksson, and generalize the standard geometric representation of a Coxeter group in such a way as to include certain restrictions of all Kac–Moody Weyl groups. In particular, a characterization of when a nontrivial multiple of a root may also be a root is given in the general context. Characterizations of when the number of such multiples of a root is finite and when the number of positive roots sent to negative roots by a group element is finite are also given. These characterizations are stated in terms of combinatorial conditions on a graph closely related to the Coxeter graph for the group. Other finiteness results for the symmetric case which are connected to the Tits cone and to a natural partial order on positive roots are extended to this asymmetric setting.
Why China Should Invest Its Foreign Exchange Reserves in the Major US Banks

The subprime mortgage crisis and the resultant inflationary monetary policy in the USA have left the Chinese economy subject to four risks in particular. First, China's exports to the USA might continue to decline. Second, in the medium term, the higher US inflation rate will lead to a weak dollar, which will negatively affect China's exports. Third, in the long term, when the US Federal Reserve decreases money supply to control inflation, the US economy might enter another recession, hurting China's exports further. Fourth, China's foreign exchange reserve assets might suffer heavy losses when the US inflation rate rises. Conventional foreign exchange investment strategies are insufficient for dealing with these four risks. Investment by China in the major US banks is suggested in the present paper. This strategy would mitigate if not eliminate all four risks. China could gain considerable financial returns on investments with only moderate risk.
Adaptive Bayesian contextual classification based on Markov random fields

In this paper an adaptive Bayesian contextual classification procedure that utilizes both spectral and spatial interpixel dependency contexts in statistics estimation and classification is proposed. Essentially, this classifier is the constructive coupling of an adaptive classification procedure and a Bayesian contextual classification procedure. In this classifier, the joint prior probabilities of the classes of each pixel and its spatial neighbors are modeled by the Markov random field. Experiments with real hyperspectral data show that, starting with a small training sample set, this classifier can reach classification accuracies similar to that obtained by a pixelwise maximum likelihood classifier with a very large training sample set. Additionally, classification maps are produced which have significantly less speckle error.
Experimental Test Results for a Fiber Bragg Grating-based Flow Sensor

A fiber optic-based mass flow sensor has been developed that uses fiber Bragg gratings to deduce flow velocity. Flow velocity, local temperature, pressure measurements (which all can be extracted using fiber Bragg gratings), and geometric information can be combined to determine mass flow.A range of concepts have each been investigated and compared using the same “design of experiment” for each sensor. The most promising concept has been further developed into a prototype. The working prototype successfully demonstrated a thermally insensitive sensor design that has the capability to track flow velocities. The sensor design is incorporated directly with a structural beam element to magnify the strain effect while simultaneously compensating for thermally induced wavelength shifts in the sensor response. Further testing has been performed using three flexible beams at different angular positions, demonstrating that flow angles can be measured using a similar approach to that used for three-hole pneumatic p...
Compliance with International Food Safety Standards in Kenya's Green Bean Industry: A Paired Case Study of Small and Large Family Farms

This study uses two farm case studies to explore how Kenyan green bean farmers are meeting European food safety standards. For green bean farmers, the standards increase the fixed costs and the transactions costs of producing beans; the standards also alter how bean quality is assessed. Both the small and the large farm use contracts to protect their specific investments in complying with the standards. However, while the large farm invests in improved facilities using its own equity, the small farm uses a marketing group to spread investment costs and reduce the transaction cost to buyers of monitoring the performance of small units. Green bean buyers face the asymmetric information problem of creating incentives for farmers to comply voluntarily with hard-to-observe production practice requirements. The buyers have responded by using closely monitored contracts, the threat of contract termination, and variable product pricing to induce compliance with the standards. The combined result of producer and buyer behavior has been to increase the scale of green bean production in Kenya. Small farms that band together in cooperative groups have succeeded in collectively attaining the scale economies needed to remain viable.
N-DIENYL AMIDES AND LACTAMS: PREPARATION AND DIELS-ALDER REACTIVITY

(1990). N-DIENYL AMIDES AND LACTAMS: PREPARATION AND DIELS-ALDER REACTIVITY. Organic Preparations and Procedures International: Vol. 22, No. 3, pp. 315-397.
Decompositions into subgraphs of small diameter

We investigate decompositions of a graph into a small number of low-diameter subgraphs. Let P(n, e, d) be the smallest k such that every graph G = (V, E) on n vertices has an edge partition E = E0 ∪ E1 ∪ ⋅⋅⋅ ∪ Ek such that |E0| ≤ en2, and for all 1 ≤ i ≤ k the diameter of the subgraph spanned by Ei is at most d. Using Szemeredi's regularity lemma, Polcyn and Rucinski showed that P(n, e, 4) is bounded above by a constant depending only on e. This shows that every dense graph can be partitioned into a small number of ‘small worlds’ provided that a few edges can be ignored. Improving on their result, we determine P(n, e, d) within an absolute constant factor, showing that P(n, e, 2) = Θ(n) is unbounded for e n−1/2 and P(n, e, 4) = Θ(1/e) for e >n−1. We also prove that if G has large minimum degree, all the edges of G can be covered by a small number of low-diameter subgraphs. Finally, we extend some of these results to hypergraphs, improving earlier work of Polcyn, Rodl, Rucinski and Szemeredi.
Capacity and optimal power allocation for fading broadcast channels with minimum rates

We derive the capacity region and optimal power allocation scheme for a slowly fading broadcast channel in which minimum rates must be maintained for each user in all fading states, assuming perfect channel state information at the transmitter and at all receivers. We show that the minimum-rate capacity region can be written in terms of the ergodic capacity region of a broadcast channel with an effective noise determined by the minimum rate requirements. This allows us to characterize the optimal power allocation schemes for minimum-rate capacity in terms of the optimal power allocations schemes that maximize ergodic capacity of the broadcast channel with effective noise. Numerical results are provided for different fading broadcast channel models.
On the Local Standard of Rest

Under the influence of a spiral gravitational field, there should be differences among the mean motions of different types of objects with different dispersion velocities in a spiral galaxy. The old stars with high dispersion velocity should have essentially no mean motion normal to the galactic rotation. On the other hand, young objects and interstellar gas may be moving relative to the old stars at a velocity of a few kilometer per second in both the radial (galacto-centric), and circular directions, depending on the spiral model adopted. Such a velocity is usually referred as the systematic motion or the streaming motion. In this paper, we shall show that the conventionally adopted local standard of rest is indeed co-moving with the young objects of the solar vicinity (also see Lin and Yuan 1974). Therefore, it has a net systematic motion with respect to the circular motion of an equilibrium galactic model, defined by the old stars.
Rising cigarette prices and rising obesity: coincidence or unintended consequence?

Economists have begun to debate if the rise in cigarette prices in the U.S. in recent decades has contributed to the nation’s rise in obesity, reaching conclusions that are surprisingly sensitive to specification. I show that allowing for the effect to occur gradually over several years leads to the conclusion that a rise in cigarette prices is actually associated with a long-run reduction in body mass index and obesity. This result is robust to the different methodologies used in the literature. I also provide evidence that indirect effects on exercise and food consumption may explain the counterintuitive result.
Wage differentials discrimination and inequality: a cautionary note on the Juhn, Murphy and Pierce decomposition method

This paper shows how difficult it is to study the roles of discrimination and unobserved skills when studying changes in racial and gender wage gaps over time by examining merits and shortcomings of a popular decomposition method by Juhn, Murphy and Pierce (JMP). The JMP method shows that wage dispersion can offer a compelling explanation of the wage gap. However, JMP have to rely on a few strong assumptions in order to derive their decomposition equation, which introduces wage inequality as the price of unobserved skills (the standard deviation of the residuals) into their decomposition equation.
Data Clustering with a Relational Push-Pull Model

We present a new generative model for relational data in which relations between objects can have ei- ther a binding or a separating effect. For example, in a group of students separated into gender clusters, a "dating" relation would appear most frequently between the clusters, but a "roommate" relation would appear more often within clusters. In visualizing these rela- tions, one can imagine that the "dating" relation effec- tively pushes clusters apart, while the "roommate" re- lation pulls clusters into tighter formations. A unique aspect of the model is that an edge's existence is depen- dent on both the clusters to which the two connected objects belong and the features of the connected objects. We use simulated annealing to search for optimal val- ues of the unknown model parameters, where the ob- jective function is a Bayesian score derived from the generative model. Results describing the performance of the model are shown with artificial data as well as a subset of the Internet Movie Database. The results show that discovering a relation's tendency to either push or pull is critical to discovering a consistent clus- tering.
Political Economic Markets: PERTs and PESTs in Food and Agriculture

•. J I lYniversity of California, Berkeley. .JJept. of agricultural and resource economic!l Working Paper ~al ClJDARE __ i. __ ~ _ _ ~ __ ... __ \'lorKing Paper :\0. 231 POLITIC\], ECO\()\lIC ]\L\RXETS: A,\D PESTS I:-J FOOD .L\,\TI ACHICULTURE by PEr~TS Cordon C. Rausser {~jA['.NlNl tt (JUNOt\TlON A riIi:ent St:!ticn Giannini. FOU:1Cl:itiol1of Ar,ricultllrnJ Econo'll i cs July 11)W:
Digital Filter Design Techniques in the Frequency Domain

In digital filtering, the spectrum is shaped using digital components as the basic elements. Although the physical realization is different, the aims of digital filtering are, thus, the same as those for continuous filtering. It is likely that digital filtering, already in extensive use for computer simulation of analog filters, will find increasing real-time application. Real-time digital filters have several advantages over their analog counterparts: a greater degree of accuracy can be attained in their realization; a larger variety can be built since certain realization problems (akin to negative elements) do not arise; no special components are needed to realize filters with time-varying coefficients; and they are of particular utility at very low frequencies where analog components become large and unwieldy. In contrast to the linear differential equations of continuous filter theory, linear digital filter theory is based on the mathematics of linear difference equations. Using the z-transform calculus, a number of digital filter design techniques are discussed. One technique is useful in designing a digital filter whose impulse response is like that of a given analog filter, whie other techniques are suitable for designing digital filters meeting specified frequency response criteria. Another yields filters with linear phase, specified frequency response, and controlled impulse response duration. The effect of digital arithmetic on digital filter behavior is considered.
Recurrence of Distributional Limits of Finite Planar Graphs

Suppose that $G_j$ is a sequence of finite connected planar graphs, and in each $G_j$ a special vertex, called the root, is chosen randomly-uniformly. We introduce the notion of a distributional limit $G$ of such graphs. Assume that the vertex degrees of the vertices in $G_j$ are bounded, and the bound does not depend on $j$. Then after passing to a subsequence, the limit exists, and is a random rooted graph $G$. We prove that with probability one $G$ is recurrent. The proof involves the Circle Packing Theorem. The motivation for this work comes from the theory of random spherical triangulations.