cssi/SciSciGPT-SciSciNet huggingface dataset:
Profile coating for KB mirror applications at the Advanced Photon Source

For microfocusing x-ray mirrors, an ellipse shape is desirable for aberration-free optics. However, it is difficult to polish elliptical mirrors to x-ray quality smoothness. A differential coating method to convert a cylindrical mirror to an elliptical one has been previously reported The differential coating was obtained by varying the sputter source power while the mirror was passed through. Here we report a new method of profile coating to achieve the same goal more effectively. In the profile coating, the sputter source power is kept constant, while the substrate is passed over a contoured mask at a constant speed. The mask is placed very close to the substrate level (within 1.0 mm) on a shield-can over the sputter gun. Four-inch-diameter Si wafers were coated through a 100-mm-long by 152-mm-wide aperture on the top of the shield-can. The thickness distribution was then obtained using a spectroscopic ellipsometer with computer-controlled X-Y translation stages. A model has been developed to fit the measured thickness distribution of stationary growth. The relative thickness weightings are then digitized at every point 1 mm apart for the entire open area of the aperture. When the substrate is moving across the shield-can during a deposition, the film thickness is directly proportional to the length of the opening on the can along the moving direction. By equating the summation of relative weighting to the required relative thickness at the same position, the length of the opening at that position can be determined. By repeating the same process for the whole length of the required profile, a contour can be obtained for a desired thickness profile. The contoured mask is then placed on the opening of the shield-can. The number of passes and the moving speed of the substrate are determined according to the required thickness and the growth-rate calibration. The mirror coating profile is determined from the ideal surface figure of a focus ellipse and that obtained from a long trace profiler on the substrate. Preliminary test results using Au as a coating material are presented.
Thickness-twist vibrations of a quartz strip

Abstract An exact solution of the three-dimensional equations of elasticity has been found for the thicknesstwist modes of vibration of a rotated-Y-cut quartz plate with a pair of parallel, free edges. The solution has a simple form: made possible by relaxing the condition that the edge-planes be perpendicular to the main faces of the plate. For the AT-cut, the edges are off perpendicular by about five degrees.
Low-Temperature Sintering and High Thermal Conductivity of YLiO2-Doped AlN Ceramics

The present work indicates through thermodynamic considerations that YLiO 2 additive is beneficial for low-temperature sintering of AlN ceramics. Pressureless sintering of commercially available AlN powders with simultaneous additions of YLiO 2 and CaO resulted in materials with high thermal conductivity (170 W.m -1 .K -1 after sintering at 1600°C for 6 h). It is demonstrated that improvement of thermal conductivity is possible at low firing temperature by use of sintering aids.
Synthesis of the Acutumine Spirocycle via a Radical−Polar Crossover Reaction

A new radical−polar crossover reaction was developed that consists of intramolecular conjugate addition of an aryl radical followed by enolate formation and hydroxylation. A C−C bond, a C−O bond, and two congested stereocenters are created in the process. The product is obtained as a single isomer. The method was used to synthesize the spirocyclic subunit of the alkaloid acutumine.
The market's response to earnings surprises after first-time going-concern modifications

Abstract This study investigates the market's response to earnings surprises after first-time going-concern modifications (GCMs). Using a sample of 581 firms and an events-study research design, we document a significant decrease in earnings response coefficients (ERCs) in the quarters following the GCM. However, this result appears to be driven by firms for which the GCM is unexpected. Specifically, we find that firms with high Z-scores prior to the GCM experience an immediate and prolonged decline in ERCs over the four quarters after the GCM, but find no change in ERCs for those firms with low Z-scores. These results are consistent with the GCM potentially resolving investors' fundamental uncertainty about future cash flows, and/or signaling that the earnings numbers generated by the firm are noisier or less persistent than was previously assumed. Further, we find no change in ERCs for a propensity-score matched control sample that did not receive GCMs, suggesting that the decline in earnings informativeness is not a response to general economic conditions. Finally, we document that institutional investors incorporate the information in the GCM. The study makes an important contribution to the going-concern literature by documenting that GCMs influence the pricing of earnings.
Enhanced Ferromagnetic Stability in Cu Doped Passivated GaN Nanowires

Density functional calculations are performed to investigate the room temperature ferromagnetism in GaN:Cu nanowires (NWs). Our results indicate that two Cu dopants are most stable when they are near each other. Compared with bulk GaN:Cu, we find that magnetization and ferromagnetism in Cu doped NWs are strongly enhanced because the bandwidth of the Cu t{sub d} band is reduced because of the one-dimensional nature of the NW. The surface passivation is shown to be crucial to sustain the ferromagnetism in GaN:Cu NWs. These findings are in good agreement with experimental observations and indicate that ferromagnetism in this type of systems can be tuned by controlling the size or shape of the host materials.
A multisensor-multitarget data association algorithm for heterogeneous sensors

The problem of associating data from three spatially distributed heterogeneous sensors with three simultaneous detections for all three is discussed. The sensors can be active or passive. The source of a detection can be either a real target, in which case the measurement is the true observation variable of the target plus measurement noise, or a spurious one, i.e. a false alarm. The sensors may have nonunity detection probabilities. The problem is to associate the measurements from sensors to identify the real targets, and to obtain their position estimates. Mathematically this leads to a generalized 3D assignment problem, which is known to be NP-hard. An algorithm suited for estimating the positions of a large number of targets in a dense cluster, using a fast, but nearly optimal, 3D assignment algorithm, is presented. Performance results for several representative test cases with 64 targets are presented. >
Incentives for Local Governments to Implement Travel Demand Management Measures

Regulatory agencies in the energy field have successfully used incentives to encourage electric and gas utilities to implement conservation measures. We develop a method for allocating federal and state funds to reward local governments that adopt effective travel demand management measures and reduce the need for expenditures on expanded roadway capacity. This method is applied to Sacramento using the region's travel demand models to forecast, for twenty and fifty year time horizons, the effects of two travel demand management scenarios: a congestion pricing scenario and a comprehensive scenario that includes congestion pricing, parking pricing, and a fuel tax. Estimates of the capital, operation, and maintenance costs were obtained from local data and are used in the financial analysis of cost savings. We found that in the Sacramento region travel demand management implementation could defer roadway projects for a minimum of 7 yr and a maximum of 24 yr, resulting in a total savings to federal and state agencies of least $100 million and at most $223 million in 1992 $, which could be used to make annual payments of at least $16 million or at most $31 million a year to local governments. Issues surrounding the technical and political feasibility of funding incentives to local governments are addressed and further research is suggested.
Stability of Rossby waves in the β-plane approximation

Abstract Floquet theory is used to describe the unstable spectrum at large scales of the β-plane equation linearized about Rossby waves. Base flows consisting of one to three Rossby waves are considered analytically using continued fractions and the method of multiple scales, while base flows with more than three Rossby waves are studied numerically. It is demonstrated that the mechanism for instability changes from inflectional to triad resonance at an O(1) transition Rhines number, Rh=U/(βL2), independent of the Reynolds number. For a single Rossby wave base flow, the critical Reynolds number Rec for instability is found in various limits. In the limits Rh→∞ and k→0, the classical value Re c = 2 is recovered. For Rh→0 and all orientations of the Rossby wave except zonal and meridional, the base flow is unstable for all Reynolds numbers; a zonal Rossby wave is stable, while a meridional Rossby wave has critical Reynolds number Re c = 2 . For more isotropic base flows consisting of many Rossby waves (up to 40), the most unstable mode is purely zonal for 2≤Rh
High-field de Haas-van Alphen measurements in Pd

The de Haas{endash}van Alphen (dHvA) effect in 99.999{percent} pure palladium has been observed in pulsed fields up to 60 T directed along [100]. We report a dHvA frequency of 73.5 kT with a cyclotron effective mass=12.5m{sub 0}. Such a frequency is not reported previously but is predicted by band theory for the open hole sheet of the Fermi surface. We also observe strong harmonic content near 50 T for the electron sheet and this is interpreted in terms of a field-dependent {ital g} factor. {copyright} {ital 1999} {ital The American Physical Society}
Effects of recombinant human hemoglobin on opossum sphincter of Oddi motor function in vivo and in vitro.

Nitric oxide (NO) acts as a nonadrenergic, noncholinergic inhibitor neurotransmitter that regulates sphincter of Oddi (SO) motor function. Hemoglobin blocks NO activity by binding it after it is synthesized. We hypothesized that recombinant human hemoglobin (rHb1.1) affects SO motor function by scavenging NO. Under anesthesia, 12 opossums underwent biliary tract manometry. Following a stabilization period, six animals were given rHb1.1 (0.28 g/kg over 30 min), while six received bovine albumin (0.28 g/kg over 30 min). Recordings were made during the infusion and for 3 hr after the infusion. In an in vitro preparation, force transducers were used to record spontaneous contractions at two sites along the sphincter segment. After a control period, rHbl.1 (0.1 mM) or cyanomethemoglobin (0.1 mM) was added to the tissue bath and recordings continued for another 2 hr. Recombinant human hemoglobin decreased the frequency of contractions, increased resting tone, and blocked the relaxation phase of contraction in vivo. It increased the baseline amplitude, the frequency, and the peak amplitudes of contractions in vitro. Albumin or cyanomethoglobin, which are unable to bind NO, had little effect on SO motor activity. We conclude that rHb1.1 may alter SO motor function by binding endogenous NO.
Pseudo transient continuation and time marching methods for Monge-Ampère type equations

We present two numerical methods for the fully nonlinear elliptic Monge-Ampere equation. The first is a pseudo transient continuation method and the second is a pure pseudo time marching method. The methods are proven to converge to a strictly convex solution of a natural discrete variational formulation with C1 conforming approximations. The assumption of existence of a strictly convex solution to the discrete problem is proven for smooth solutions of the continuous problem and supported by numerical evidence for non smooth solutions.
Control of Nonlinear Systems Using Terminal Sliding Modes

Many robotic systems would, in the future, be required to operate in environments that are highly unstructured and active, i.e., possessing means of self-actuation. Although a significant volume of results exist in model-based, robust and adaptive control literature, general issues pertinent to the performance of such control systems remain unresolved, e.g., feasibility of implementing high gain switches for control robustness. It is also pointed out that in certain applications, control switching can be very detrimental to the overall system. The primary focus of this paper is development of a new approach to control synthesis for robust robot operations in unstructured environments. To enhance control performance with full model information, we introduce the notion of terminal convergence, and develop control laws based upon a new class of sliding modes, denoted terminal sliders
Orthogonality in organic, polymer, and supramolecular chemistry: from Merrifield to click chemistry

The concept of orthogonality has been applied to many areas of chemistry, ranging from wave functions to chromatography. But it was Barany and Merrifield's orthogonal protecting group strategy that paved the way for solid phase peptide syntheses, other important classes of biomaterials such as oligosaccharides and oligonucleotides, and ultimately to a term in widespread usage that is focused on chemical reactivity and binding selectivity. The orthogonal protection strategy has been extended to the development of orthogonal activation, and recently the click reaction, for streamlining organic synthesis. The click reaction and its variants are considered orthogonal as the components react together in high yield and in the presence of many other functional groups. Likewise, supramolecular building blocks can also be orthogonal, thereby enabling programmed self-assembly, a superb strategy to create complex architectures. Overall, orthogonal reactions and supramolecular interactions have dramatically improved the syntheses, the preparation of functional materials, and the self-assembly of nanoscale structures.
A method for the efficient construction and sampling of vector-valued translation random fields

Abstract A method is developed for the efficient construction and sampling of vector-valued translation random processes and fields. Given a target marginal CDF and target covariance function, the approach is to approximate the spectral densities of the Gaussian image by a linear sum of shape functions, where each is scaled by a constant. An efficient optimization algorithm is developed to solve for the unknown constants. The objective function to be minimized is equal to the mean-square difference between the target covariance function, and the translated version of the approximate covariance function; a complex set of constraint equations is enforced during the optimization routine to ensure that the resulting covariance function of the Gaussian image is positive definite. It is shown that classical Monte Carlo simulation techniques can be used to generate samples of the Gaussian images of these models and map them into desired non-Gaussian samples. Several examples are considered to illustrate the application of the proposed method and to assess its accuracy.
A Unified Approach to Deterministic Encryption: New Constructions and a Connection to Computational Entropy

This paper addresses deterministic public-key encryption schemes (DE), which are designed to provide meaningful security when only source of randomness in the encryption process comes from the message itself. We propose a general construction of DE that unifies prior work and gives novel schemes. Specifically, its instantiations include: The first construction from any trapdoor function that has sufficiently many hardcore bits.The first construction that provides "bounded" multi-message security (assuming lossy trapdoor functions). The security proofs for these schemes are enabled by three tools that are of broader interest: A weaker and more precise sufficient condition for semantic security on a high-entropy message distribution. Namely, we show that to establish semantic security on a distribution M of messages, it suffices to establish indistinguishability for all conditional distribution M|E, where E is an event of probability at least 1/4. (Prior work required indistinguishability on all distributions of a given entropy.)A result about computational entropy of conditional distributions. Namely, we show that conditioning on an event E of probability p reduces the quality of computational entropy by a factor of p and its quantity by log21/p.A generalization of leftover hash lemma to correlated distributions. We also extend our result about computational entropy to the average case, which is useful in reasoning about leakage-resilient cryptography: leaking ? bits of information reduces the quality of computational entropy by a factor of 2? and its quantity by ?.
A Simple and Efficient Randomized Byzantine Agreement Algorithm

A new randomized Byzantine agreement algorithm is presented. This algorithm operates in a synchronous system of n processors, at most t of which can fail. The algorithm reaches agreement in 0(t/log n) expected rounds and O(n2tf/log n) expected message bits independent of the distribution of processor failures. This performance is further improved to a constant expected number of rounds and O(n2) message bits if the distribution of processor failures is assumed to be uniform. In either event, the algorithm improves on the known lower bound on rounds for deterministic algorithms. Some other advantages of the algorithm are that it requires no cryptographic techniques, that the amount of local computation is small, and that the expected number of random bits used per processor is only one. It is argued that in many practical applications of Byzantine agreement, the randomized algorithm of this paper achieves superior performance.
Atmospheric soundings from AIRS/AMSU/HSB

AIRS was launched on EOS Aqua on May 4, 2002, together with AMSU A and HSB, to form a next generation polar orbiting infrared and microwave atmospheric sounding system. The primary products of AIRS/AMSU/HSB are twice daily global fields of atmospheric temperature-humidity profiles, ozone profiles, sea/land surface skin temperature, and cloud related parameters including OLR. The sounding goals of AIRS are to produce 1 km tropospheric layer mean temperatures with an rms error of lK, and 1 km tropospheric layer precipitable water with an rms error of 20%, in cases with up to 80% effective cloud cover. Pre-launch simulation studies indicated that these results should be achievable. Minor modifications have been made to the pre-launch retrieval algorithm as alluded to in this paper. Sample fields of parameters retrieved from AIRS/AMSU/HSB data are presented and temperature profiles are validated as a function of retrieved effective fractional cloud cover. As in simulation, the degradation of retrieval accuracy with increasing cloud cover is small. Select fields are also compared to those contained in the ECMWF analysis, done without the benefit of AIRS data, to demonstrate information that AIRS can add to that already contained in the ECMWF analysis. Assimilation of AIRS temperature soundings in up to 80% cloud cover for the month of January 2003 into the GSFC FVSSI data assimilation system resulted in improved 5 day forecasts globally, both with regard to anomaly correlation coefficients and the prediction of location and intensity of cyclones.
STEERING CONTROLLER DESIGN FOR AUTOMATED GUIDEWAY TRANSIT VEHICLES

The fundamental lateral performance capabilities of rubber-tired automated guideway transit (AGT) vehicles operating under automatic steering control on exclusive guideways are discussed. Control is achieved by steering the front wheels in response to signals derived from the position errors between the vehicle and a guideway-based reference containing random irregularities. Optimal control techniques are used to synthesize controllers which minimize a performance index consisting of mean square lateral acceleration and tracking error, defining a frontier which limits the performance of steering controllers. Simple single-sensor proportional steering controllers are found to offer performance comparable to the optimum for a typical AGT vehicle. The degradations in performance arising from dynamic lags in the steering actuator and operation at off-design speeds are shown.
Domain Wall Fermions and chiral symmetry restoration rate

Abstract Domain Wall Fermions utilize an extra space time dimension to provide a method for restoring the regularization induced chiral symmetry breaking in lattice vector gauge theories even at finite lattice spacing. The breaking is restored at an exponential rate as the size of the extra dimension increases. As a precursor to lattice QCD studies the dependence of the restoration rate to the other parameters of the theory and, in particular, the lattice spacing is investigated in the context of the two flavor lattice Schwinger model.
Magnetic characteristics of R2Fe14 − xMnxB systems (R ≡ Y, Nd, Pr and Gd)

Abstract Magnetic properties of R 2 Fe 14 − x Mn x B systems (R ≡ Y, Nd, Pr, Gd) were investigated over a large temperature range. All the compounds studied crystallized in the tetragonal R 2 Fe 14 B structure. The substitution of iron by manganese rapidly decreased the Curie temperatures and saturation moments. The anisotropy field H A at 77 K is found to increase, especially for R ≡ Pr compounds. The spin-reorientation temperature is lowered by manganese substitution for the Nd 2 (Fe, Mn) 14 B systems, and the cone angle θ is also reduced.
A Stochastic Approach to Chemical Evolution

Observations of elemental abundances in the Galaxy have repeatedly shown an intrinsic scatter as a function of time and metallicity. The standard approach to chemical evolution does not attempt to address this scatter in abundances since only the mean evolution is followed. In this work, the scatter is addressed via a stochastic approach to solving chemical evolution models. Three simple chemical evolution scenarios are studied using this stochastic approach: a closed box model, an infall model, and an outflow model. These models are solved for the solar neighborhood in a Monte Carlo fashion. The evolutionary history of one particular region is determined randomly based on the star formation rate and the initial mass function. Following the evolution in an ensemble of such regions leads to the predicted spread in abundances expected, based solely on different evolutionary histories of otherwise identical regions. In this work, 13 isotopes are followed, including the light elements, the CNO elements, a few α-elements, and iron. It is found that the predicted spread in abundances for a 105 M☉ region is in good agreement with observations for the α-elements. For CN, the agreement is not as good, perhaps indicating the need for more physics input for low-mass stellar evolution. Similarly for the light elements, the predicted scatter is quite small, which is in contradiction to the observations of 3He in H II regions. The models are tuned for the solar neighborhood so that good agreement with H II regions is not expected. This has important implications for low-mass stellar evolution and on using chemical evolution to determine the primordial light-element abundances in order to test big bang nucleosynthesis.
Consistent poverty comparisons and inference

Building upon the cost of basic needs (CBN) approach, an integrated approach to making consumption-based poverty comparisons is presented. This approach contains two principal modifications to the standard CBN approach. The first permits the development of multiple poverty bundles that are utility consistent. The second recognizes that the poverty line itself is a random variable whose variation influences the degree of confidence in poverty measures. We illustrate the empirical importance of these two methodological changes for the case of Mozambique. With utility consistency imposed, estimated poverty rates tend to be systematically higher in rural areas and lower in urban areas. We also find that the true confidence intervals on the poverty estimates—those incorporating poverty line variance—tend to be considerably larger than those that ignore poverty line variance. Finally, we show that these two methodological changes interact. Specifically, we find that imposing utility consistency on poverty bundles tends to tighten confidence intervals, sometimes dramatically, on provincial poverty estimates. We conclude that this revised approach represents an important advance in poverty analysis. The revised approach is straightforward and directly applicable in empirical work.
Wave propagation in the Tether Elevator/Crawler System

Abstract This paper analyzes the propagation of disturbances along the upper-tether of the Tether Elevator/Crawler System. Both longitudinal and transverse waves are investigated as the waves propagate from the station to the elevator, and beyond to the upper-platform. The model takes into account the effects of gravity gradient and material damping. An estimate of the various damping mechanisms affecting transverse waves is also provided in the paper. The frequency response functions at the elevator and at the upper-platform are computed for either a longitudinal or a transverse perturbation of the tether attachment point to the station.
Efficient Algorithms for Computing the Jacobi Symbol

We present two new algorithms for computing the Jacobi Symbol: the right-shift and left-shiftk-ary algorithms. For inputs of at mostnbits in length, both algorithms takeO(n2/logn) time andO(n) space. This is asymptotically faster than the traditional algorithm, which is based in Euclid's algorithm for computing greatest common divisors. In practice, we found our new algorithms to be about twice as fast for inputs of 100 to 1000 decimal digits in length. We also present parallel versions of both algorithms for the CRCW PRAM. One version takesO?(n/ loglogn) time usingO(n1+?) processors, giving the first sublinear parallel algorithms for this problem. The other version takes polylog time using a subexponential number of processors.
Impact of classes of development coordination tools on software development performance: A multinational empirical study

Although a diverse variety of software development coordination tools are widely used in practice, considerable debate surrounds their impact on software development performance. No large-scale field research has systematically examined their impact on software development performance. This paper reports the results of a multinational field study of software projects in 209 software development organizations to empirically examine the influence of six key classes of development coordination tools on the efficiency (reduction of development rework, budget compliance) and effectiveness (defect reduction) of software development performance.Based on an in-depth field study, the article conceptualizes six holistic classes of development coordination tools. The results provide nuanced insights—some counter to prevailing beliefs—into the relationships between the use of various classes of development coordination tools and software development performance. The overarching finding is that the performance benefits of development coordination tools are contingent on the salient types of novelty in a project. The dimension of development performance—efficiency or effectiveness—that each class of tools is associated with varies systematically with whether a project involves conceptual novelty, process novelty, multidimensional novelty (both process and conceptual novelty), or neither. Another noteworthy insight is that the use of some classes of tools introduces an efficiency-effectiveness tradeoff. Collectively, the findings are among the first to offer empirical support for the varied performance impacts of various classes of development coordination tools and have important implications for software development practice. The paper also identifies several promising areas for future research.
Enzyme Catalyzed Regioselective Synthesis of Sucrose Fatty Acid Ester Surfactants

Abstract A commercial subtilisin preparation was used in pyridine to catalyze the regioselective conversion of sucrose and fatty acid vinyl esters into the 1′-O-acyl sucrose derivatives. The 1′-O-laury sucrose, 1′-O-myristyl sucrose and 1′-O-stearyl sucrose were obtained as the major products of these reactions. The 1′,6-di-O-acyl sucrose derivatives were also obtained as minor products. The critical micellar concentration (CMC) of each of these sucrose monoesters was determined.
New Asymptotically Sharp Korn and Korn-Like Inequalities in Thin Domains

It is well known that Korn inequality plays a central role in the theory of linear elasticity. In the present work we prove new asymptotically sharp Korn and Korn-like inequalities in thin curved domains with a non-constant thickness. This new results will be useful when studying the buckling of compressed shells, in particular when calculating the critical buckling load.
Chemistry with an Artificial Primer of Polyhydroxybutyrate Synthase Suggests a Mechanism for Chain Termination

Polyhydroxybutyrate (PHB) synthases (PhaCs) catalyze the conversion of 3-(R)-hydroxybutyryl CoA (HBCoA) to PHB, which is deposited as granules in the cytoplasm of microorganisms. The class I PhaC from Caulobacter crescentus (PhaC(Cc)) is a highly soluble protein with a turnover number of 75 s(-1) and no lag phase in coenzyme A (CoA) release. Studies with [1-(14)C]HBCoA and PhaC(Cc) monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and autoradiography reveal that the rate of elongation is much faster than the rate of initiation. Priming with the artificial primer [(3)H]sTCoA and monitoring for CoA release reveal a single CoA/PhaC, suggesting that the protein is uniformly loaded and that the elongation process could be studied. Reaction of sT-PhaC(Cc) with [1-(14)C]HBCoA revealed that priming with sTCoA increased the uniformity of elongation, allowing distinct polymerization species to be observed by SDS-PAGE and autoradiography. However, in the absence of HBCoA, [(3)H]sT-PhaC unexpectedly generates [(3)H]sDCoA with a rate constant of 0.017 s(-1). We propose that the [(3)H]sDCoA forms via attack of CoA on the oxoester of the [(3)H]sT-PhaC chain, leaving the synthase attached to a single HB unit. Comparison of the relative rate constants of thiolysis by CoA and elongation by PhaC(Cc), and the size of the PHB polymer generated in vivo, suggests a mechanism for chain termination and reinitiation.
Speakeasy: a window into a computer

Speakeasy is a system that enables a user to harness the power of a computer as a tool for problem solving. This paper describes the structure of that system and demonstrates some of its capabilities. The examples show some of the power that results when relatively straightforward graphical facilities are added to this general purpose system.
A simple model of globalization, schooling and skill acquisition $

We develop a model of schooling and skill acquisition, highlighting informational asymmetries that distort the incentives to educate. A key feature of our model is that education acts simultaneously as a signaling device and as a method for workers to enhance their productivity. We show that when firms can only imperfectly screen workers, the result is an economy in which too many workers purchase schooling and too few workers devote sufficient effort to their coursework to qualify for the high skill labor pool. We then examine how greater openness to international markets alters the skill mix of the domestic workforce and show that greater openness usually eases one labor market distortion while making the other distortion worse. Globalization impacts educational behavior and labor market outcomes differently as the extent of firms engaged in international markets varies, and affects wage inequality both within and across educational groups.
Picosecond photoinduced absorption and polarization memory in polythiophene derivatives

Although the fast dynamics of photoexcitations have been thoroughly explored in the conjugated polymer trans-polyacetylene, the experimental picture is much less complete for polymers in which the ground state is nondegerate. We report time-resolved photoinduced absorption data from films of one family of such polymers: the soluble polythiophene derivatives, poly(3-hexylthiophene) and poly(3-octylthiophene). Fast (<10−12s bleaching of the interband transition is observed at 2.06 eV, accompanied by subgap photoinduced aborption at 1.17 eV. The results indicate a shift of a fraction of the oscillator strength, consistent with rapid structural relaxation to form polarons with associated gap states. By varying the polarization of the optical probe relative to that of the pump, photoinduced dichroism is observed. The magnitude of the initial dichroism implies that in spin-cast films the polymers are (locally) chain extended and chain aligned. The time decay of the polarization memory is consistent with rapid trapping of the initially mobile charged excitations.
Evidence for an explosive origin of central pit craters on Mars

Abstract Kilometer-scale pits are nested in the centers of many impact craters on Mars as well as on icy satellites. They have been inferred to form in the presence of a water–ice rich substrate; however, the process(es) responsible for their formation is still debated. Previous models invoke origins by either explosive excavation of potentially water-bearing crustal material, or by subsurface drainage of meltwater and/or collapse. If explosive excavation forms central pits, pit-derived ejecta should be draped around the pits, whereas internal collapse should not deposit significant material outside pit rims. Using visible wavelength images from the Mars Reconnaissance Orbiter (MRO) Context Camera (CTX) and High Resolution Imaging Science Experiment (HiRISE) instruments and thermal infrared images from the Odyssey Thermal Emission Imaging System (THEMIS) instrument, we conducted a survey to characterize, in detail, the global population of central pits in impact craters ⩾10 km in diameter. We specifically examined the morphology and thermophysical characteristics of the pits for evidence of pit ejecta. Our analysis of thermal images suggests that coarse-grained materials are distributed proximally around many central pits on the floors of their host craters. The decrease in average grain size with distance from pit rims is consistent with pit-derived ejecta. These observations and interpretations better support an explosive origin for central pits on Mars than they do an origin of subsurface meltwater drainage and collapse of the overlying substrate. A major weakness to previous explosive central pit formation models is the inability for them to form pits late enough in the impact process to be preserved. To address this, we present an alternative “melt contact model” where a central uplift brings ice-bearing substrate into contact with impact melt to generate steam explosions and excavate central pits during the impact modification stage. Theoretical calculations show that more than enough thermal energy is available via impact melt from the host crater to form central pits by steam explosions, and such explosions would require only a modest amount (2–6% by volume) of uplifted water–ice. We therefore propose that central pits on Mars could have formed explosively by the interaction of impact melt and subsurface water–ice.
A Green Chemistry Approach to Ibuprofen Piconol

Abstract Ibuprofen piconol synthesis has been described. The use of solid catalyst has demonstrated green chemistry approach with promoted atom economy of 94% compared to the reported 68%. †DRL Publication No: 430.
Knowledge Transfer with Low-Quality Data: A Feature Extraction Issue

Effectively utilizing readily available auxiliary data to improve predictive performance on new modeling tasks is a key problem in data mining. In this research, the goal is to transfer knowledge between sources of data, particularly when ground-truth information for the new modeling task is scarce or is expensive to collect where leveraging any auxiliary sources of data becomes a necessity. Toward seamless knowledge transfer among tasks, effective representation of the data is a critical but yet not fully explored research area for the data engineer and data miner. Here, we present a technique based on the idea of sparse coding, which essentially attempts to find an embedding for the data by assigning feature values based on subspace cluster membership. We modify the idea of sparse coding by focusing the identification of shared clusters between data when source and target data may have different distributions. In our paper, we point out cases where a direct application of sparse coding will lead to a failure of knowledge transfer. We then present the details of our extension to sparse coding, by incorporating distribution distance estimates for the embedded data, and show that the proposed algorithm can overcome the shortcomings of the sparse coding algorithm on synthetic data and achieve improved predictive performance on a real world chemical toxicity transfer learning task.
Postbuckling behavior of selected flat stiffened graphite-epoxy panels loaded in compression

Results of an experimental study of the postbuckling behavior of selected flat stiffened graphite-epoxy panels loaded in compression are presented. The postbuckling response and failure characteristics of undamaged panels and panels damaged by low-speed impact are described. Each panel had four equally-spaced I-spaced stiffeners and 16- or 24-ply quasi-isotropic skins. Panels with three different stiffener spacings were tested. Some undamaged specimens supported as much as three times their initial buckling load before failing. Failure of all panels initiated in a skin-stiffener interface region. Analytical results obtained from a nonlinear general shell finite element analysis computer code correlate well with typical postbuckling test results up to failure. The analytical modeling detail necessary to predict accurately the response of a panel is described. Test results show that low-speed impact damage can reduce the postbuckling strength of a stiffened panel and that the skin-stiffener interface region is more sensitive to impact damage than the skin midway between stiffeners.
The parity operator in quantum optical metrology

Photon number states are assigned a parity of +1 if their photon number is even and a parity of −1 if odd. The parity operator, which is minus one to the power of the photon number operator, is a Hermitian operator and thus a quantum mechanical observable although it has no classical analogue, the concept being meaningless in the context of classical light waves. In this paper we review work on the application of the parity operator to the problem of quantum metrology for the detection of small phase shifts with quantum optical interferometry using highly entangled field states such as the so-called N00N states, and states obtained by injecting twin Fock states into a beam splitter. With such states and with the performance of parity measurements on one of the output beams of the interferometer, one can breach the standard quantum limit, or shot-noise limit, of sensitivity down to the Heisenberg limit, the greatest degree of phase sensitivity allowed by quantum mechanics for linear phase shifts. Heisenber...
Optimal trajectories of air and space vehicles

The author developed a theory of optimal trajectories for air vehicles with variable wing area and conventional wings. He applied a new theory of singular optimal solutions and obtained the optimal flight in many cases. At first glance, the results may seem strange however, this is correct and this paper will show how this new theory may be used. The main idea of the research is in using the vehicle's kinetic energy for increasing the range of missiles and projectiles. The author shows that the range of a ballistic warhead can be increased 3‐4 times if an optimal wing is added to the ballistic warhead, especially a wing with variable area. If increased range is not needed, the warhead mass can be increased. The range of big gun shells can also be increased 3‐9 times. The range of aircraft may be improved 3‐15 percent and more. The results can be used for the design of aircraft, missiles, flying bombs and shells of big guns.
Initial blow-up of solutions of semilinear parabolic inequalities

Abstract We study classical nonnegative solutions u ( x , t ) of the semilinear parabolic inequalities 0 ⩽ u t − Δ u ⩽ u p in Ω × ( 0 , 1 ) where p is a positive constant and Ω is a bounded domain in R n , n ⩾ 1 . We show that a necessary and sufficient condition on p for such solutions u to satisfy a pointwise a priori bound on compact subsets K of Ω as t → 0 + is p ⩽ 1 + 2 / n and in this case the bound on u is max x ∈ K u ( x , t ) = O ( t − n / 2 ) as t → 0 + . If in addition, Ω is smooth, u satisfies the boundary condition u = 0 on ∂ Ω × ( 0 , 1 ) , and p 1 + 2 / n , then we obtain a bound for u on the entire set Ω as t → 0 + .
Argon laser treatment of the red nose.

. Ten patients with red nose due to telangiectasias were treated with the argon laser. Seven had telangiectasias due to rosacea, two had had rhinoplasty, and one had experienced trauma. All of the patients had a good clinical result.
The abundance of dark galaxies

We show that gas in a large fraction of low-mass dark matter haloes may form Toomre-stable discs, if angular momentum is conserved when the gas contracts. Such haloes would be stable to star formation and therefore remain dark. This may potentially explain deviation between the predicted and the observed faint-end slope of the luminosity function and the discrepancy between the predicted and observed number of dwarf satellites in the Local Group. The above mechanism does not require a strong variation of the baryon fraction with the virial mass of the dark halo. We show that model fits to rotation curves are also consistent with this hypothesis: none of the observed galaxies lies in the region of parameter space forbidden by the Toomre stability criterion.
Partition function for the eigenvalues of the Wilson line

Abstract In a gauge theory at nonzero temperature the eigenvalues of the Wilson line form a set of gauge invariant observables. By constructing the corresponding partition function for the phases of these eigenvalues, we prove that the trivial vacuum, where the phases vanish, is a minimum of the free energy.
Free and Complexed R3M+ Cations (M = Ge, Sn, Pb)

1 Introduction 2 Preparation 3 Structure and Properties 4 Reactions 5 Related Species 6 Conclusions Keywords: heavier congeners of carbenium ions; Sn NMR chemical shifts for cationic tin species; germyl cations in sulfolane and dichloromethane; B3LYP/SSD method and ion-pairing energies for optimized isomers; intramolecular stabilization; electron impact ionization; crystal structure of free cyclotrigermenium cation; free trimesitylgermyl and trimesitylstannyl cations
Decentralizing Allocation and Distribution by Separation with Information Transfers

Governments often divide operations into separate branches that face different constraints and have limited information. Such separation is feasible if each can operate by solving a simple optimization problem using limited information without requiring game-theoretic calculations about others' actions. We specify two structures of one-way information transfers that allow this. For each structure, we present conditions for unified and decentralized decision-making to have identical outcomes. One of them corresponds to using a Samuelson aggregate welfare function that is not always fully efficient. We apply our results to several examples, including public goods and Ramsey pricing.
Spike sorting the other way

Abstract The problem of identifying neural activity from extracellular recordings is still with us. In recent years there have been a lot of improvements in clustering and identification over the first simple techniques. However, the manner in which data samples are selected as putative spike candidates has remained almost unchanged. This part of data processing still remains a largely heuristic procedure. In this work we offer a more quantitative approach to identifying putative spike shapes, which then serve as inputs to clustering methods.
Magnetic measurements of monolayer-thickness films of Cr sandwiched by Au

Abstract Calculations show ferromagnetic moments (3.1μB) in Au-Cr-Au sandwiches, for monolayers of Cr. The measured moment (0.41μB at 2 K) is larger in Cr monolayers than for thicker Cr samples. Results are discussed in terms of other studies of this system including those which showed superconductivity.
Wintel: Cooperation and Conflict

We study competitive interactions between Intel and Microsoft, two producers of complementary products. In a system of complements, like the PC, the value of the final product depends on how well the different components work together. This, in turn, depends on the firms' investment in complementary R&D. We ask whether Intel and Microsoft will want to cooperate and make the final product as valuable as possible. Contrary to the popular view that two tight complements will generally have well aligned incentives, we demonstrate that natural conflicts emerge over pricing, the timing of new product releases, and who captures the greatest value at different phases of product generations.
Eigenvalues, invariant factors, highest weights, and Schubert calculus

We describe recent work of Klyachko, Totaro, Knutson, and Tao that characterizes eigenvalues of sums of Hermitian matrices and decomposition of tensor products of representations of GLn(C). We explain related applications to invariant factors of products of matrices, intersections in Grassmann varieties, and singular values of sums and products of arbitrary matrices. Recent breakthroughs, primarily by A. Klyachko, B. Totaro, A. Knutson, and T. Tao, with contributions by P. Belkale and C. Woodward, have led to complete solutions of several old problems involving the various notions in the title. Our aim here is to describe this work and especially to show how these solutions are derived from it. Along the way, we will see that these problems are also related to other areas of mathematics, including geometric invariant theory, symplectic geometry, and combinatorics. In addition, we present some related applications to singular values of arbitrary matrices. Although many of the theorems we state here have not appeared elsewhere, their proofs are mostly “soft” algebra based on the hard geometric or combinatorial work of others. Indeed, this paper emphasizes concrete elementary arguments. We do give some new examples and counterexamples and raise some new open questions. We have attempted to point to the sources and to some of the key partial results that had been conjectured or proved before. However, there is a very large literature, particularly for linear algebra problems about eigenvalues, singular values, and invariant factors. We have listed only a few of these articles, from whose bibliographies, we hope, an interested reader can trace the history; we apologize to the many whose work is not cited directly. We begin in the first five sections by describing each of the problems, together with some of their early histories, and we state as theorems the new solutions to these problems. In Section 6 we describe the steps toward these solutions that were carried out before the recent breakthroughs. Then we discuss the recent solutions and explain how these theorems follow from the work of the above mathematicians. Sections 7, 8, 9, and 10 also contain variations and generalizations of some of the theorems stated in the first five sections, as well as attributions of the theorems to their authors. One of our fascinations with this subject, even now that we have proofs of the theorems, is the challenge to understand in a deeper way why all these subjects are Received by the editors in July 1999 and in revised form January 3, 2000. 2000 Mathematics Subject Classification. Primary 15A42, 22E46, 14M15; Secondary 05E15, 13F10, 14C17, 15A18, 47B07. The author was partly supported by NSF Grant #DMS9970435. c ©2000 American Mathematical Society