cssi/SciSciGPT-SciSciNet huggingface dataset:
Self-Organizing wireless sensor networks in action

Wireless sensor networks (WSN) composed of large numbers of small devices that self-organize are being investigated for a wide variety of applications. Two key advantages of these networks over more traditional sensor networks are that they can be dynamically and quickly deployed, and that they can provide fine-grained sensing. Applications, such as emergency response to natural or manmade disasters, detection and tracking, and fine grained sensing of the environment are key examples of applications that can benefit from these types of WSN. Current research for these systems is widespread. However, many of the proposed solutions are developed with simplifying assumptions about wireless communication and the environment, even though the realities of wireless communication and environmental sensing are well known. Many of the solutions are evaluated only by simulation. In this talk I describe a fully implemented system consisting of a suite of more than 30 synthesized protocols. The system supports a power aware surveillance, tracking and classification application running on 203 XSM motes and evaluated in a realistic, large-area environment. Technical details and evaluations are presented. I end with a discussion of opportunities and problems for data mining related to WSN.
An Approach to Describing the Simultaneous Erosion and High-Temperature Oxidation of Alloys

The rate of wastage of an alloy surface subjected to erosion under conditions where high-temperature oxidation can occur can be significantly greater than that arising from erosion alone. This is because the erosion conditions can act to accelerate the oxidation process by causing regular shedding of the otherwise protective oxide scale. It is suggested that an important parameter in determining the rate of erosion-oxidation is the erodent flux, since the time available for oxide growth (or regrowth) in a given area is determined by the interval between successive erodent impacts. Using this simple premise, an approach is suggested by which the rate of erosion-oxidation can be related to the factors that control the alloy oxidation process, and those that describe the erosive environment. The assumptions made are examined, and some of the implications of this approach are discussed.Copyright © 1990 by ASME
Synthesis of Substituted 1,4-Dienes by Direct Alkylation of Allylic Alcohols

A regio- and stereoselective cross-coupling reaction between unactivated allylic alcohols and alkynes is described for the synthesis of 1,4-dienes.
The State: Agent or Proprietor?

This paper addresses the following question: Does characterizing the state to be an agent of its citizens provide a useful “as if” framework for positive analysis of economic policy? Or, can we understand economic policy only by explicitly characterizing the state as proprietary, the instrument of the ruling elite?
INEQUALITY IN THE DISTRIBUTION OF PERSONAL INCOME IN THE WORLD: HOW IT IS CHANGING AND WHY *

The variance in the logarithms of per capita GDP in purchasing-power-parity prices increased in the world from 1960 to 1968 and decreased since the mid 1970s. In the later period the convergence in intercountry incomes more than offset any increase in within country inequality. Approximately two-thirds of this measure of world inequality is intercountry, three-tenths interhousehold within country inequality, and one-twentieth between gender differences in education. If China is excluded from the world sample, the decline in world inequality after 1975 is not evident. Measuring confidently trends in household and gender inequality will requires much improved data.
Improving information quality of sensory data through asynchronous sampling

In this paper, asynchronous sampling is proposed as a novel approach to improve the information quality of sensory data through shifting the sampling moments of sensors from each other. The exponential correlation model and the entropy model for the sensory data are introduced to quantify their information quality. An asynchronous sampling strategy, EASS, is presented accordingly to assign equal time shifts to sensors, which in turn reduces data correlation and thus improves information quality in terms of increased entropy of sensory data. A lower bound for EASS is derived to evaluate its effectiveness. Simulation results based on both synthetic data and experimental data are satisfactory.
Firm Transparency and the Costs of Going Public

We demonstrate that firms that are more transparent pay less, in all components of issuance costs, to go puhlic. We employ a sample of 334 previous leveraged huyouts and a characteristic-matched control sample to test the hypothesis that greater firm transparency hefore the issue decreases the flotation costs of the initial public offering. These flotation costs are divided into initial underpricing, underwriter discount, administrative expenses, and the overallotment option required to take the firm public. Our results provide further evidence of the asymmetric information hypothesis as it applies to initial public offerings,
Low Income and Poor Health Choices: The Example of Smoking

People with low incomes tend to make less healthy consumption choices than do high income people. In the case of food, agricultural economists have investigated whether this is due to the cost of a healthy diet. Studies of various aspects of the nutrition-income nexus have generally been inconclusive. We investigate a different possibility, motivated by the fact that low income individuals are most likely to be smokers, which cannot be due to limited budgets. Drawing on a body of related literature, we develop a model in which income serves not only as a budget constraint but also as a source of future utility. We test the model by estimating logistic models of beginning and quitting smoking. We find support for the idea that low income consumers make less healthy choices because they face lower costs in terms of foregone future utility.
Ballistic missile track initiation from satellite observations

An algorithm is presented to initiate tracks of a ballistic missile in the initial exoatmospheric phase, using line of sight (LOS) measurements from one or more moving platforms (typically satellites). The major feature of this problem is the poor target motion observability which results in a very ill-conditioned estimation problem. The Gauss-Newton iterative least squares minimization algorithm for estimating the state of a nonlinear deterministic system with nonlinear noisy measurements has been previously applied to the problem of angles-only orbit determination using more than three observations. A major shortcoming of this approach is that convergence of the algorithm depends strongly on the initial guess. By using the more sophisticated Levenberg-Marquardt method in place of the simpler Gauss-Newton algorithm and by developing robust new methods for obtaining the initial guess in both single and multiple satellite scenarios, the above mentioned difficulties have been overcome. In addition, an expression for the Cramer-Rao lower bound (CRLB) on the error covariance matrix of the estimate is derived. We also incorporate additional partial information as an extra pseudomeasurement and determine a modified maximum likelihood (ML) estimate of the target state and the associated bound on the covariance matrix. In most practical situations, probabilistic models of the target altitude and/or speed at the initial point constitute the most useful additional information. Monte Carlo simulation studies on some typical scenarios were performed, and the results indicate that the estimation errors are commensurate with the theoretical lower bounds, thus illustrating that the proposed estimators are efficient. >
Fault location in cellular arrays

Testing of complex integrated cellular logic circuits fabricated using LSI techniques has become a source of concern to users and manufacturers. Since an economically feasible solution to testing problems is not visible for the complex arrays contemplated for the near future, manufacturers have acknowledged the seriousness of the problem. Currently some observers believe that LSI cannot be tested because general procedures for testing and diagnosing digital circuits are applicable to small networks of approximately 30 gates, while cellular arrays are contemplated as containing hundreds or thousands of gates on one chip. However, if arrays are constrained to be in a cellular form, then testing problems can be simplified and test schedules can be produced which use the interconnection structure of cellular arrays.
TRANSONIC FLOW CALCULATIONS USING TRIANGULAR FINITE ELEMENTS

Princeton University, Princeton, NJ This paper desribes a technique for finding the numerical solution of the Full Potential equation for steady transonic flow about airfoils. The exterior but finite domain is discretized by breaking it up into triangles. Difference equations are formulated using variational principle and a formula for the derivative in an arbitrary polygon. The iterative schemes include multigrid-AD1 for structured grids and modified checkerboard for more arbitrary grids. Results show consistency and compare favorably with codes using quadrilateral elements.
Frequency Stability of L-Band, Two-Port Dielectric Resonator Oscillators

Dielectric resonator oscillators operating at 1.5 GHz and 2.0 GHz, based on a two-port resonator design incorporated into a basic feedback loop oscillator configuration, were evaluated and show state-of-the art, close-to-carrier phase noise performance. Typically, at 1-kHz carrier offset frequency the single-sideband phase noise levels were -130 dBc/Hz and -120 dBc/Hz for the 1.5-GHz and 2.0-GHz oscillators, respectively. Vibration sensitivity was also investigated and the resonators show fractional frequency changes per g in the range of 10/sup -7/ to 10/sup -9/ for the 1.5-GHz and 2.0-GHz designs. Finally, measurements were performed to characterize both the static and dynamic temperature sensitivities of the 2.0-GHz dielectric resonator oscillator design. The static temperature coefficient was found to be approximately -1.40 ppm/°C, while the dynamic temperature coefficient was nominally -3000 ppm/°C/s, at 27.5°C.
Dichromatic dark matter

Both the robust INTEGRAL 511 keV gamma-ray line and the recent tentative hint of the 135GeV gamma-ray line from Fermi-LAT have similar signal morphologies, and may be produced from the same dark matter annihilation. Motivated by this observation, we construct a dark matter model to explain both signals and to accommodate the two required annihilation cross sections that are different by more than six orders of magnitude. In our model, to generate the low-energy positrons for INTEGRAL, dark matter particles annihilate into a complex scalar that couples to photon via a charge-radius operator. The complex scalar contains an excited state decaying into the ground state plus an off-shell photon to generate a pair of positron and electron. Two charged particles with non- degenerate masses are necessary for generating this charge-radius operator. One charged particle is predicted to be long-lived and have a mass around 3.8TeV to explain the dark matter thermal relic abundance from its late decay. The other charged particle is predicted to have a mass below 1TeV given the ratio of the two signal cross sections. The 14TeV LHC will concretely test the main parameter space of this lighter charged particle.
Expanding xylose metabolism in yeast for plant cell wall conversion to biofuels

Sustainable biofuel production from renewable biomass will require the efficient and complete use of all abundant sugars in the plant cell wall. Using the cellulolytic fungus Neurospora crassa as a model, we identified a xylodextrin transport and consumption pathway required for its growth on hemicellulose. Reconstitution of this xylodextrin utilization pathway in Saccharomyces cerevisiae revealed that fungal xylose reductases act as xylodextrin reductases, producing xylosyl-xylitol oligomers as metabolic intermediates. These xylosyl-xylitol intermediates are generated by diverse fungi and bacteria, indicating that xylodextrin reduction is widespread in nature. Xylodextrins and xylosyl-xylitol oligomers are then hydrolyzed by two hydrolases to generate intracellular xylose and xylitol. Xylodextrin consumption using a xylodextrin transporter, xylodextrin reductases and tandem intracellular hydrolases in cofermentations with sucrose and glucose greatly expands the capacity of yeast to use plant cell wall-derived sugars and has the potential to increase the efficiency of both first-generation and next-generation biofuel production.
Constitutional afterlife: The continuing impact of Thailand's postpolitical constitution

Thailand’s constitution of 1997 introduced profound changes into the country’s governance, creating a “postpolitical” democratic structure in which an intricate array of guardian institutions served to limit the role of elected politicians. Ultimately, the constitutional structure was undermined in a military coup against populist billionaire Thaksin Shinawatra, who had taken over many of the institutions designed to constrain political power. Nonetheless, the 1997 constitution appears to be having a significant afterlife, in that its institutional innovations have survived the enactment of a new Constitution and continue to constrain the political process. This article describes the Thai situation and speculates on the conditions for constitutional afterlife.
Dockets, Deals, and Sagas Commensuration and the Rationalization of Experience in University Licensing

University Technology Licensing Offices (TLOs) are strategic sites for examining efforts to concretize, frame, and market early stage technologies. This paper draws on 18 months of fieldwork in a private university TLO to analyze collective decision-making efforts during licensing meetings. I describe three processes - docket description, deal framing, and problem resolution - that highlight the central roles that locally sensible strategies and languages play in describing and comparing disparate technologies. Such approaches reflect the collective experience of licensing associates and, when rationalized through organizational learning, represent the processual underpinnings of ongoing transformations in the institutional arrangements of US universities. Close examination of meeting discussions reveals multiple ‘conceptual spaces’ that support TLO decision-making and more closely connects theoretical work in science and technology studies with theories of organizational learning and with economic sociol...
Asymmetric aldol reactions. Mechanism of solvent effect on stereoselectivity is specific, stoichiometric binding of tetrahydrofuran to a chiral titanium enolate

Abstract Solvent plays an important role in aldol reactions of an acyloxazolidinone-derived titanium enolate. Diethyl ether produces nearly fivefold higher diastereofacial selectivity than THF. We now show that this strong solvent effect arises from stoichiometric binding, most probably to the titanium, of THF in the transition structure, whereas ether is not bound. These mechanistic results indicate that THF lowers the selectivity by interfering with chelation control, which is highly preferred in ether. Implications include the possibility of using other ethers to improve chelation/nonchelation control still more, or even use of chiral ethers as chiral controller groups or adjuncts.
Labor Market Developments During Economic Transition

The paper reviews labor market developments in the transition economies of Europe and Central Asia. It argues that the scarcity of productive job opportunities and the growing labor market segmentation are the two main labor market problems facing the transition economies. In the European transition economies the lack of jobs has led to persistent open unemployment. In the Commonwealth of Independent States (CIS) it has led to hidden unemployment (underemployment and low productivity employment). Unemployment in the European transition economies is supported by the developed social safety net. In contrast, in the CIS for most workers unemployment is not an affordable option. They either stick to their old, unproductive jobs in unrestructured enterprises, or work in the informal sector, or resort to subsistence agriculture. Thus, underemployment in the CIS is a mirror image of unemployment in the European transition economies. Accordingly, the high employment-to-population ratios in many CIS countries do not necessarily signify favorable labor market performance. Instead they often indicate delayed enterprise restructuring, the maintenance of unsustainable jobs in uncompetitive firms, and the existence of a large informal sector as an employer of last resort. Labor market segmentation has been caused by a sharp increase in earnings differentials and the attendant increase in the incidence of low-paid jobs, by the polarization of regional labor market conditions, and finally by the growth of the informal sector offering casual, low-productivity jobs. Labor market segmentation and accompanying inequalities are more pronounced in the CIS than in the European transition economies.
The Rise of the Chinese Security State

Over the past two decades, the Chinese domestic security apparatus has expanded dramatically. “Stability maintenance” operations have become a top priority for local Chinese authorities. We argue that this trend goes back to the early 1990s, when central Party authorities adopted new governance models that differed dramatically from those of the 1980s. They increased the bureaucratic rank of public security chiefs within the Party apparatus, expanded the reach of the Party political-legal apparatus into a broader range of governance issues, and altered cadre evaluation standards to increase the sensitivity of local authorities to social unrest. We show that the origin of these changes lies in a policy response to the developments of 1989–1991, namely the Tiananmen democracy movement and the collapse of communist political systems in Eastern Europe. Over the past twenty years, these practices have developed into an extensive stability maintenance apparatus, whereby local governance is increasingly oriented around the need to respond to social unrest, whether through concession or repression. Chinese authorities now appear to be rethinking these developments, but the direction of reform remains unclear.
Design and applications of an avionics system for a miniature acrobatic helicopter

This paper describes the avionics developed for a miniature acrobatic helicopter and the applications for such a system. The avionics system is designed to safely achieve a robust, high-bandwidth feedback control system while meeting physical specifications. The system that is currently implemented has provided an efficient platform for testing new closed-loop controllers and has yielded critical flight data used for developing simple models of small-scale helicopter dynamics. The helicopter has already demonstrated successful flight under a body-axis velocity/heading rate-tracking controller.
Shape-selective oxidation of primary alcohols using perruthenate-containing zeolites

Potassium perruthenate (KRuO4), a known, effective oxidant for the conversion of primary and secondary alcohols into carbonyl compounds is impregnated into zeolite X and shown to be a shape-selective oxidant using benzyl alcohol (reacted) and pyrenemethanol (not reacted).
Intramolecular [4 + 2] cycloadditions of benzynes with conjugated enynes, arenynes, and dienes.

Benzynes generated by the reaction of o-(trimethylsilyl)aryl triflates with TBAT participate in intramolecular [4 + 2] cycloadditions with conjugated enynes, arenynes, and dienes to furnish highly condensed polycyclic aromatic compounds.
Gravitational waves from scattering of stellar-mass black holes in galactic nuclei

Stellar-mass black holes (BHs) are expected to segregate and form a steep density cusp around supermassive black holes (SMBHs) in galactic nuclei. We follow the evolution of a multimass system of BHs and stars by numerically integrating the Fokker–Planck energy diffusion equations for a variety of BH mass distributions. We find that the BHs ‘self-segregate’, and that the rarest, most massive BHs dominate the scattering rate closest to the SMBH (10 −1 pc). BH–BH binaries form out of gravitational wave emission during BH encounters. We find that the expected rate of BH coalescence events detectable by Advanced LIGO is ∼1–10 2 yr −1 , depending on the initial mass function of stars in galactic nuclei and the mass of the most massive BHs. We find that the actual merger rate is likely ∼10 times larger than this due to the intrinsic scatter of stellar densities in many different galaxies. The BH binaries that form this way in galactic nuclei have significant eccentricities as they enter the LIGO band (90 per cent with e> 0.9), and are therefore distinguishable from other binaries, which circularize before becoming detectable. We also show that eccentric mergers can be detected to larger distances and greater BH masses than circular mergers, up to ∼700 M � . Future ground-based gravitational wave observatories will be able to constrain both the mass function of BHs and stars in galactic nuclei.
Cross-linking of polytetrafluoroethylene during room-temperature irradiation

Abstract Exposure of polytetrafluoroethylene (PTFE) to α-radiation was investigated to determine the physical and chemical effects, as well as to compare and contrast the damage mechanisms with other radiation types (β, γ, or thermal neutron). A number of techniques were used to investigate the chemical and physical changes in PTFE after exposure to α-radiation. These techniques include: Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and fluorescence spectroscopy. Similar to other radiation types at low doses, the primary damage mechanism for the exposure of PTFE to α-radiation appears to be chain scission. Increased doses result in a change-over of the damage mechanism to cross-linking. This result is not observed for any radiation type other than α when irradiation is performed at room temperature. Finally, at high doses, PTFE undergoes mass-loss (via small-fluorocarbon species evolution) and defluorination. The amount and type of damage versus sample depth was also investigated. Other types of radiation yield damage at depths on the order of mm to cm into PTFE due to low linear energy transfer (LET) and the correspondingly large penetration depths. By contrast, the α-radiation employed in this study was shown to only induce damage to a depth of approximately 26 μm, except at very high doses.
Weighted Projective Spaces and a Generalization of Eves' Theorem

For a certain class of configurations of points in space, Eves' Theorem gives a ratio of products of distances that is invariant under projective transformations, generalizing the cross-ratio for four points on a line. We give a generalization of Eves' theorem, which applies to a larger class of configurations and gives an invariant with values in a weighted projective space. We also show how the complex version of the invariant can be determined from classically known ratios of products of determinants, while the real version of the invariant can distinguish between configurations that the classical invariants cannot.
Generalized Adaptive Network Coded Cooperation (GANCC): A Unified Framework for Network Coding and Channel Coding

Previous work introduced the idea of matching network codes with network graphs to handle the network dynamics. This paper further integrates channel coding in the adaptive network coding framework through an elegant treatment of circulant shifting. Several code constructions are developed. Theoretical analysis and simulations show that the resultant generalized adaptive network coded cooperation (GANCC) is simple, adaptive, distributive, and capable of remarkable coding gains even with a very small number of cooperating users.
The Impact of Postsecondary Remediation using a Regression Discontinuity Approach: Addressing Endogenous Sorting and Noncompliance

Remedial or developmental courses are the most common policy instruments used to assist underprepared postsecondary students who are not ready for college-level coursework. However, despite their important role in higher education and its substantial costs, there is little rigorous evidence on the effectiveness of college remediation on the outcomes of students. This study uses a detailed dataset to identify the causal effect of remediation on the educational outcomes of nearly 100,000 college students in Florida, an important state that reflects broader national trends in remediation policy and student diversity. Using a Regression Discontinuity design, we provide causal estimates while also investigating possible endogenous sorting around the policy cutoff, which could pose a threat to the assumptions of the RD model. As a robustness check, we implement methods proposed by McCrary (2008) and discuss the strengths of this approach. The results suggest math and reading remedial courses have mixed benefits. Being assigned to remediation appears to increase persistence to the second year and the total number of credits completed for students on the margin of passing out of the requirement, but it does not increase the completion of college-level credits or eventual degree completion. Taken together, the results suggest that remediation might promote early persistence in college, but it does not necessarily help students on the margin of passing the placement cutoff make long-term progress toward earning a degree.
An RFQ injection system for the HRIBF

At the Holifield Radioactive Ion Beam Facility (HRIBF) at Oak Ridge National Laboratory (ORNL), molecular ions extracted from a positive ion source and subsequently broken up in a charge-exchange cell produce Radioactive Ion Beams (RIBs) with several hundred eV energy spread, preventing effective magnetic isobar separation. In order to perform magnetic isobar separation prior to charge exchange, a multi-harmonic buncher and a 12-MHz RFQ (Radio-Frequency Quadrupole) is proposed to supplement the present 300-kV injection system for the 25-MV tandem electrostatic accelerator. The RFQ will be mounted on a variable high voltage platform to accelerate ions with masses from 10 to 150 amu.
Performance Bounds on Synchronous Laser Line Scan Systems

In this article a performance bound is derived for feasible image resolution among a class of imaging systems that can be referred to as synchronous laser line scan systems. Most often, these systems use a narrow beam projected source (typically a laser) in conjunction with a very small field of view receiver that is synchronously scanned. Here, a bound on the maximum system resolution is derived when both source and receiver are "delta function like". The bound demonstrates that the best achievable overall system point spread function is the square of the one way point spread function for the medium.
The Effect of Geometric Enhancement on the Magnetic Saw Effect

This paper proposes that in some instances, the magnetic saw effect is purely a melt phenomenon and describes a series of experiments where the magnetic saw effect was studied by varying the submillimeter radius of the enhancement point on a set of highly controlled samples. The magnetic saw effect is an instability that can occur when high currents are required to make sharp bends, thereby greatly enhancing the magnetic field and current densities. These sharp bends generally occur at joints, cuts, or other flaws and can cause failure of high-current conductors. The magnetic saw effect has also been proposed as a possible metal-cutting mechanism for manufacturing purposes. Due to the very small length scales of the features associated with magnetic sawing, it is difficult to make samples that are controlled enough to get reproducible experimental results for systematic studies. In these experiments, printed circuit board technology was used to accurately make samples with very fine enhancement features. The conditions for the magnetic saw effect were modeled using an electromagnetic code to establish the important parameters that predict the onset of damage.
[U.S. warns on some use of anti-AIDS drug].

The new way with nevirapine was reported to prevent mother-to-child transmission of the AIDS virus (HIV) that also is less costly and markedly more effective than the standard therapy with AZT in the third world. The more practical therapy comes from substituting one marketed drug, nevirapine, for the standard drug, AZT. It was proposed that widescale use of nevirapine in developing countries could potentially prevent 300,000 to 400,000 newborns each year from beginning life infected with HIV. But in September, 2000, the Center for Disease Control and Prevention (CDC) received reports of life-threatening hepatotoxicity (liver damage) among health care workers taking nevirapine for post-exposure prophylaxis (PEP) after occupational exposure to HIV. Furthermore, persons taking nevirapine regimens for PEP after HIV exposure also are at risk for serious and adverse events. The federal Food and Drug Administration (FDA) had identified 22 cases of severe liver, skin and muscle damage related to nevirapine taken after possible exposure to HIV from March 1997 through September 2000. Nevirapin has not been recommended for PEP use, and has previously been associated with instances of serious skin or muscle conditions, liver damage, and death when used for treating HIV-infected individuals. In most circumstances, the risks associated with nevirapine as part of an occupational PEP regimen might outweigh the anticipated benefits.
Do Participants and Observers Assess Intentions Differently During Bargaining and Conflict

Political actors in conflict settings are often uncertain about their counterparts' intentions. This article explores the psychology of how intentions are assessed using a novel experimental design that randomly assigns subjects to one of three roles—“proposer,”“recipient,” or “observer.” Recipients and observers are given identical noisy information about proposers' actions, and make postplay assessments of proposers' intentions that are rewarded based on accuracy. A first experiment explores a context of ambiguity, while a second experiment explores a context of uncertainty. The results suggest that actors' perceptions can sometimes be directly affected by the set of strategic alternatives they possess. When signals about proposer behavior appear “negative,” recipients' assessments of proposers' intentions are more negative than observers' assessments if recipients have the ability to respond to the proposer's action—but not if recipients lack this ability. The ability to respond to proposer behavior appears to cause recipients to make more negative inferences about the proposer than circumstances warrant. Interestingly, recipients' and observers' assessments are indistinguishable when signals about proposer behavior instead appear “positive.”
From Nothing, Everything

Void Universalism is, arguably, Sergei Prozorov’s magnum opus. Consisting of two volumes, Ontology and World Politics (OWP) and Theory of the Political Subject (TPS), Void Universalism links the individual to the international, the particular to the universal, and nothing to everything. With this publication, Sergei Prozorov establishes himself as the most innovative contemporary scholar in international political theory, placing himself on equal terms with Alain Badiou, Jean-Luc Nancy, and Giorgio Agamben, with whom his work is in deep conversation. He writes with a precision that exemplifies a command of sophisticated concepts that is unparalleled.
Higher-Order Defect-Mode Laser in an Optically Thick Photonic Crystal Slab

The use of an optically thick slab may provide versatile solutions for the realization of a current injection-type laser using photonic crystals. Here, we show that a transversely higher-order defect mode can be designed to be confined by a photonic bandgap in such a thick slab. Using simulations, we show that a high Q of >10(5) is possible from a finely tuned second-order hexapole mode (2h). Experimentally, we achieve optically pumped pulsed lasing at 1347 nm from the 2h with a peak threshold pump power of 88 μW.
Microscopic Study of Metal Hydrides using Electron Spin resonance

Electron spin resonance (ESR) of dilute paramagnetic ions in nonmagnetic metallic hydrides provides microscopic information about the hydrogen ions in the immediate vicinity of the impurity. By comparing ESR spectra for different host metals and several hydrogen/metal ratios, one can determine material properties including host lattice symmetry, phase boundaries and occupation of available sites by hydrogen. Examples are presented of ESR of dilute Er in group IIIB and IVB metal hydrides, demonstrating the sensitivity and versatility of ESR as a spectroscopic technique.
Complexity of gradient projection method for optimal routing in data networks

In this paper, we derive a time-complexity bound for the gradient projection method for optimal routing in data networks. This result shows that the gradient projection algorithm of Goldstein-Levitin-Poljak type formulated by Bertsekas (1982), Bertsekas and Gallager (1987) and Bertsekas et al. (1984) converges to within /spl epsi/ in relative accuracy in O(/spl epsi//sup -2/h/sub min/N/sub max/) number of iterations, where N/sub max/ is the number of paths sharing the maximally shared link, and h/sub min/ is the diameter of the network. Based on this complexity result, we also show that the one-source-at-a-time update policy has a complexity bound which is O(n) times smaller than that of the all-at-a-time update policy, where n is the number of nodes in the network. The result of this paper argues for constructing networks with low diameter for the purpose of reducing complexity of the network control algorithms. The result also implies that parallelizing the optimal routing algorithm over the network nodes is beneficial.
Unique Minimal Liftings for Simplicial Polytopes

For a minimal inequality derived from a maximal lattice-free simplicial polytope in Rn, we investigate the region where minimal liftings are uniquely defined, and we characterize when this region covers Rn. We then use this characterization to show that a minimal inequality derived from a maximal lattice-free simplex in Rn with exactly one lattice point in the relative interior of each facet has a unique minimal lifting if and only if all the vertices of the simplex are lattice points.
Racial Differences in Home Ownership and Home Equity Among Preretirement-Aged Households

This article measures the racial disparities in home ownership and home equity among preretirement-aged households. It computes the proportion of the racial gap explained by discrimination in housing and credit markets. Maximum likelihood and nonlinear least squares estimates are obtained for models of home ownership probabilities and home equity, conditional on home ownership, yielding computations for expected home equity for black and white households. The results reveal an average discriminatory gap in expected home equity as a percent of the actual gap of 55%. In the top third of the family income distribution, the measured discriminatory gap is 82%; in the middle third it is 83%; in the lowest third it is 62%.
Randomized approximation algorithms for set multicover problems with applications to reverse engineering of protein and gene networks

In this paper we investigate the computational complexities of a combinatorial problem that arises in the reverse engineering of protein and gene networks. Our contributions are as follows: We abstract a combinatorial version of the problem and observe that this is “equivalent” to the set multicover problem when the “coverage” factor k is a function of the number of elements n of the universe. An important special case for our application is the case in which k=n–1. We observe that the standard greedy algorithm produces an approximation ratio of Ω(log n) even if k is “large” i.e.k=n–c for some constant c>0. Let 1<a<n denotes the maximum number of elements in any given set in our set multicover problem. Then, we show that a non-trivial analysis of a simple randomized polynomial-time approximation algorithm for this problem yields an expected approximation ratio E[r(a,k)] that is an increasing function of a/k. The behavior of E[r(a,k)] is “roughly” as follows: it is about ln (a/k) when a/k is at least about e 2≈ 7.39, and for smaller values of a/k it decreases towards 2 exponentially with increasing k with lim a/ k→0 E[r(a,k)]≤ 2. Our randomized algorithm is a cascade of a deterministic and a randomized rounding step parameterized by a quantity β followed by a greedy solution for the remaining problem.
The Chromatic Number of Random Regular Graphs

Given any integer d ≥ 3, let k be the smallest integer such that d < 2k log k. We prove that with high probability the chromatic number of a random d-regular graph is k, k+1, or k+2.
Ablation of vitreous tissue with a high repetition rate erbium:YAG laser.

PURPOSE To quantify erbium (Er):YAG laser ablation of vitreous in relation to different pulse repetition rates < or = 200 Hz, in order to examine the feasibility of laser for removal of vitreous gel (photovitrectomy) in clinically acceptable times. METHODS Fresh porcine vitreous samples and saline controls were ablated in air with an Er:YAG laser connected to a sapphire fiber at pulse energies between 1.0 and 21.2 mJ and at pulse repetition rates between 10 and 200 Hz. Net ablation rates were determined by weight measurement. RESULTS Reproducible and constant ablation rates were found for given laser parameters. Net ablation rates increased linearly with pulse repetition rate and nonlinearly with pulse energy. Expanded laser parameter domains permitted vitreous ablation rates as low as 1 microg/s to as high as 1031 microg/s. Ablation rates did not differ significantly between vitreous and saline. CONCLUSIONS The study documents clinically useful vitreous ablation rates that scale linearly with high repetition rates of Er:YAG laser, and suggests directions for further development of laser technology for enhanced removal of vitreous and other tissues. However, nonlinear effects of pulse energy also exist, indicating need for careful examination of ablation characteristics in various instruments.
ABSOLUTE DIMENSIONS OF THE G7+K7 ECLIPSING BINARY STAR IM VIRGINIS: DISCREPANCIES WITH STELLAR EVOLUTION MODELS

We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IM Vir, composed of a G7-type primary and a K7 secondary. With these observations, we derive accurate absolute masses and radii of M 1 = 0.981 ? 0.012 M ?, M 2 = 0.6644 ? 0.0048 M ?, R 1 = 1.061 ? 0.016 R ?, and R 2 = 0.681 ? 0.013 R ? for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 ? 100 K and 4250 ? 130 K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory. We find that both stars are larger than the models predict, by 3.7% for the primary and 7.5% for the secondary, as well as cooler than expected, by 100 K and 150 K, respectively. These discrepancies are in line with previously reported differences in low-mass stars, and are believed to be caused by chromospheric activity, which is not accounted for in current models. The effect is not confined to low-mass stars: the rapidly rotating primary of IM Vir joins the growing list of objects of near-solar mass (but still with convective envelopes) that show similar anomalies. The comparison with the models suggests an age of 2.4 Gyr for the system, and a metallicity of [Fe/H] ?0.3 that is consistent with other indications, but requires confirmation.
Structured recursive separator decompositions for planar graphs in linear time

Given a triangulated planar graph G on n vertices and an integer r<n, an r--division of G with few holes is a decomposition of G into O(n/r) regions of size at most r such that each region contains at most a constant number of faces that are not faces of G (also called holes), and such that, for each region, the total number of vertices on these faces is O(√ r). We provide an algorithm for computing r--divisions with few holes in linear time. In fact, our algorithm computes a structure, called decomposition tree, which represents a recursive decomposition of G that includes r--divisions for essentially all values of r. In particular, given an exponentially increasing sequence {vec r} = (r1,r2,...), our algorithm can produce a recursive {vec r}--division with few holes in linear time. r--divisions with few holes have been used in efficient algorithms to compute shortest paths, minimum cuts, and maximum flows. Our linear-time algorithm improves upon the decomposition algorithm used in the state-of-the-art algorithm for minimum st--cut (Italiano, Nussbaum, Sankowski, and Wulff-Nilsen, STOC 2011), removing one of the bottlenecks in the overall running time of their algorithm (analogously for minimum cut in planar and bounded-genus graphs).
Catalytic cleavage of ether C-O bonds by pincer iridium complexes

The development of efficient catalytic methods to cleave the relatively unreactive C-O bonds of ethers remains an important challenge in catalysis. Building on our group's recent work, we report the dehydroaryloxylation of aryl alkyl ethers using pincer iridium catalysts. This method represents a rare fully atom-economical method for ether C-O bond cleavage.
Statistical shape influence in geodesic active contours

A novel method of incorporating shape information into the image segmentation process is presented. We introduce a representation for deformable shapes and define a probability distribution over the variances of a set of training shapes. The segmentation process embeds an initial curve as the zero level set of a higher dimensional surface, and evolves the surface such that the zero level set converges on the boundary of the object to be segmented. At each step of the surface evolution, we estimate the maximum a posteriori (MAP) position and shape of the object in the image, based on the prior shape information and the image information. We then evolve the surface globally; towards the MAP estimate, and locally based on image gradients and curvature. Results are demonstrated on synthetic data and medical imagery in 2D min 3D.
Results on the redundancy of universal compression for finite-length sequences

In this paper, we investigate the redundancy of universal coding schemes on smooth parametric sources in the finite-length regime. We derive an upper bound on the probability of the event that a sequence of length n, chosen using Jeffreys' prior from the family of parametric sources with d unknown parameters, is compressed with a redundancy smaller than (1 − ∈) d over 2 log n for any ∈ > 0. Our results also confirm that for large enough n and d, the average minimax redundancy provides a good estimate for the redundancy of most sources. Our result may be used to evaluate the performance of universal source coding schemes on finite-length sequences. Additionally, we precisely characterize the minimax redundancy for two-stage codes. We demonstrate that the two-stage assumption incurs a negligible redundancy especially when the number of source parameters is large. Finally, we show that the redundancy is significant in the compression of small sequences.
Large size LYSO crystals for future high energy physics experiments

Because of their high stopping power and fast bright scintillation, cerium doped silicate based heavy crystal scintillators, such as GSO, LSO, and LYSO, have been developed for medical instruments. Their applications in high energy and nuclear physics, however, are limited by lacking high quality crystals in sufficiently large size. The optical and scintillation properties, including the transmittance, emission and excitation spectra and the light output, decay kinetics and light response uniformity, as well as their degradation under gamma-ray irradiation were measured for two long (2.5times2.5times20 cm) LYSO samples from CPI and Saint-Gobain, and were compared to a BGO sample of the same size from SIC. Possible applications for crystal calorimetry in future high energy and nuclear physics experiments are discussed
On spherical harmonics for fuzzy spheres in diverse dimensions

Abstract We construct spherical harmonics for fuzzy spheres of even and odd dimensions, generalizing the correspondence between finite Matrix algebras and fuzzy two-spheres. The finite Matrix algebras associated with the various fuzzy spheres have a natural basis which falls in correspondence with tensor constructions of irreducible representations of orthogonal groups SO ( n ). This basis is useful in describing fluctuations around various D-brane constructions of fuzzy spherical objects. The higher fuzzy spheres are non-associative algebras that appear as projections of associative algebras related to matrices. The non-associativity (as well as the non-commutativity) disappears in the leading large N limit, ensuring the correct classical limit. Some simple aspects of the combinatorics of the fuzzy four-sphere can be accounted by a heuristic picture of giant fractional instantons.
Anisotropic magnetization and resistivity of single crystalline RNi1−xBi2±y (R = La–Nd, Sm, Gd–Dy)

We present a detailed study of RNi1−xBi2±y (R = La–Nd, Sm, Gd–Dy) single crystals by measurements of stoichiometry and temperature dependent magnetic susceptibility, magnetization, and electrical resistivity. This series forms with partial Ni occupancy, 0.72 ⩽ (1−x) ⩽ 0.84, as well as a variable Bi occupancy, 1.76 ⩽ (2±y) ⩽ 2.14. For R = Ce–Nd, Gd–Dy, the RNi1−xBi2±y compounds show local-moment like behavior and order antiferromagnetically at low temperatures. Determination of anisotropies as well as antiferromagnetic ordering temperatures for RNi1−xBi2±y (R = Ce–Nd, Sm, Gd–Dy) have been made. Crystalline samples from this family exhibit minority, second phase superconductivity at low temperatures, which can be associated with Ni–Bi and Bi contamination. No evidence of bulk superconductivity has been observed.
Insights for light-driven molecular devices from ab initio multiple spawning excited-state dynamics of organic and biological chromophores.

We discuss the basic process of photoinduced isomerization as a building block for the design of complex, multifunctional molecular devices. The excited-state dynamics associated with isomerization is detailed through application of the ab initio multiple spawning (AIMS) method, which solves the electronic and nuclear Schrodinger equations simultaneously. This first-principles molecular dynamics approach avoids the uncertainties and extraordinary effort associated with fitting of potential energy surfaces and allows for bond rearrangement processes with no special input. Furthermore, the AIMS method allows for the breakdown of the Born−Oppenheimer approximation and thus can correctly model chemistry occurring on multiple electronic states. We show that charge-transfer states play an important role in photoinduced isomerization and argue that this provides an essential “design rule” for multifunctional devices based on isomerizing chromophores.