cssi/SciSciGPT-SciSciNet huggingface dataset:
High indium metamorphic HEMT on a GaAs substrate

Abstract Metamorphic high electron mobility transistor structures with high indium content channel layers have been developed on GaAs substrates by solid source molecular beam epitaxy. After grading the buffer layer to In 0.64 Al 0.36 As, a single pulse doped structure was grown with a composite In 0.65 Ga 0.35 As/In 0.80 Ga 0.20 As channel. The RMS surface roughness of a 25 μm×25 μm area was 11 A. Cross sectional and plan view transmission electron microscopy measurements indicated planar interfaces and a surface dislocation density 6 cm −2 . For a sheet density of 2.8×10 12 cm −2 , the 300 and 77 K mobilities were 13,500 and 45,400 cm 2 /V s. The 300 K mobility was consistent with increasing mobility with indium channel content and compared favorably with highly strained structures grown on InP substrates. Initial transistor structures with a gate length of 0.14 μm exhibited a current density of 800 mA/mm, a transconductance of 1.5 S/mm, an F t of 170 GHz, and F max of 250 GHz. Low voltage operation was demonstrated with a current density of 200 mA/mm obtained at a source–drain bias of 0.1 V. These results are very encouraging toward extending growth of metamorphic transistor structures to the pseudomorphically forbidden compositional region between InP and InAs.
Spatial statistical models that use flow and stream distance

We develop spatial statistical models for stream networks that can estimate relationships between a response variable and other covariates, make predictions at unsampled locations, and predict an average or total for a stream or a stream segment. There have been very few attempts to develop valid spatial covariance models that incorporate flow, stream distance, or both. The application of typical spatial autocovariance functions based on Euclidean distance, such as the spherical covariance model, are not valid when using stream distance. In this paper we develop a large class of valid models that incorporate flow and stream distance by using spatial moving averages. These methods integrate a moving average function, or kernel, against a white noise process. By running the moving average function upstream from a location, we develop models that use flow, and by construction they are valid models based on stream distance. We show that with proper weighting, many of the usual spatial models based on Euclidean distance have a counterpart for stream networks. Using sulfate concentrations from an example data set, the Maryland Biological Stream Survey (MBSS), we show that models using flow may be more appropriate than models that only use stream distance. For the MBSS data set, we use restricted maximum likelihood to fit a valid covariance matrix that uses flow and stream distance, and then we use this covariance matrix to estimate fixed effects and make kriging and block kriging predictions.
Schubert Varieties and Free Braidedness

We give a simple necessary and sufficient condition for a Schubert variety Xw to be smooth when w is a freely braided element of a simply laced Weyl group; such elements were introduced by the authors in a previous work. This generalizes in one direction a result of Fan concerning varieties indexed by short-braid avoiding elements. We also derive generating functions for the freely braided elements that index smooth Schubert varieties. All results are stated and proved only for the simply laced case.
An efficient synthesis of enyne[3]cumulenes

Abstract The Pd(PPh 3 ) 4 -catalyzed cross coupling between 3 and terminal alkynes furnished enynyl aldehydes 4 , which were converted to 6 by condensation with 5 . Sequential treatment of 6 with n -butyllithium, methanesulfonyl chloride, and tetrabutylammonium fluoride (TBAF) afforded enyne[3]cumulenes 8 .
Moire Interferometry For Deformation And Strain Studies

Recent advances in high sensitivity moire interferometry are described. In-plane displacement fields are shown for very challenging problem areas: adhesive joints in tension and in bending, flexure of quasi-isotropic composite laminates, and fatigue cracks in aluminum. Reference gratings with 2400 lines/mm (60,960 //in.) were used, providing a sensitivity of 0.417 Am/fringe order (16.4 Ain./fringe order). Excellent fringe contrast was obtained in all cases, even for gradients of 64 fringes/mm (1600 fringes/in.). A four-beam optical system to produce two orthogonal virtual reference gratings was employed. The question of unknown relative displacements in two-body problems was answered by use of a soft bridge between the bodies to provide a continuous path for the fringe count.
A modified Kähler–Ricci flow

In this note, we study a Kahler–Ricci flow modified from the classic version. In the non-degenerate case, strong convergence at infinite time is achieved. The main focus should be on degenerate case, where some partial results are presented.
Addition of diprotic nucleophiles to a C60-tetrazine monoadduct: structural reassignment and correction of a novel rearrangement.

C60–tetrazine Diels–Alder adducts bearing electron deficient dihydropyridazine groups undergo chemoselective amination and hydration reactions upon addition of primary aliphatic amines and water, respectively, to form new adducts with 4,5-dihydropyrazole groups nested atop the [60]fullerene skeleton.
Investment under uncertainty and option value in environmental economics

A question has arisen concerning the relationship between the financial theory of options and the concept of option value developed in the literature on environmental preservation. This article presents simple models in each approach and then demonstrates their equivalence. The conventional, differing interpretations of results in the two approaches are also shown to be consistent though consideration of the difference can lead to a deeper understanding of the concept of option value.
Short-Term National Airspace System Delay Prediction Using Weather Impacted Traffic Index

This paper describes a method to predict delay in the National Airspace System for durations of up to two hours. Various linear autoregressive model structures with exogenous inputs were implemented to perform the delay prediction. Current and forecast weather impacted traffic indices and air traffic volume were used as inputs to the system while the air traffic delay is the predicted output of the model. The refined methodology for generating the weather impacted traffic indices, together with the high-update-rate of Corridor Integrated Weather System is well suited for real-time delay prediction. An adaptive scheme was implemented to provide both weather-related and non-weather-related delay predictions depending on the weather and air traffic condition. The method will benefit air traffic management by facilitating the development of strategies to reduce delays, cancellations, and other costs during the day of operations in various weather conditions.
Numerical determination of Lissajous trajectories in the restricted three-body problem

In previous studies, Lissajous trajectories associated with the collinear libration points in the restricted three-body problem have been successfully computed analytically to at least third-order. Those approximations are utilized to determine such trajectories numerically for an arbitrary, predetermined number of revolutions in the rotating frame, for the case of circular primary motion. The numerical approach first identifies target positions at specified intervals along the trajectory and locates a continuous path through those points with velocity discontinuities. Then the Δv are simultaneously reduced in an iterative process. Such trajectories have been constructed in various primary systems, for a wide range of orbit sizes and a large number of revolutions.
Anonymous credentials light

We define and propose an efficient and provably secure construction of blind signatures with attributes. Prior notions of blind signatures did not yield themselves to the construction of anonymous credential systems, not even if we drop the unlinkability requirement of anonymous credentials. Our new notion in contrast is a convenient building block for anonymous credential systems. The construction we propose is efficient: it requires just a few exponentiations in a prime-order group in which the decisional Diffie-Hellman problem is hard. Thus, for the first time, we give a provably secure construction of anonymous credentials that can work in the elliptic group setting without bilinear pairings and is based on the DDH assumption. In contrast, prior provably secure constructions were based on the RSA group or on groups with pairings, which made them prohibitively inefficient for mobile devices, RFIDs and smartcards. The only prior efficient construction that could work in such elliptic curve groups, due to Brands, does not have a proof of security.
On the origin of radial magnetic fields in the heliosphere

[1] Numerous examples of events wherein the heliospheric magnetic field (HMF) measured at a fixed point in space remains nearly radial for many hours have been reported in the literature. Such events are observed both in the normal solar wind and within disturbances driven by coronal mass ejections (CMEs). A very large fraction of these extended, nearly radial HMF intervals, whose average duration increases with increasing distance from the Sun, occur at times when the solar wind flow speed is declining gradually. Typically, when mapped back to the Sun using a constant speed-with-distance approximation, all portions of a given radial field event appear to have left the Sun at approximately the same time. Here we propose that these nearly radial HMF events result from temporally abrupt and semipermanent decreases in solar wind flow speed on these same field lines close to the Sun. The abrupt flow speed changes may be the result of an interchange reconnection of field lines that extend into the heliosphere with closed coronal loops. In our kinematic model a radially directed kink in the magnetic field connects the different spirals associated with the faster and slower flows immediately preceding and following the temporal flow speed discontinuity. With increasing heliocentric distance the length of the kink grows while the temporal flow speed discontinuity that produces it evolves into a gradual spatial flow speed decline.
Synthesis of Acyclic Ketones by Catalytic, Bidirectional Homologation of Formaldehyde with Nonstabilized Diazoalkanes. Application of a Chiral Diazomethyl(pyrrolidine) in Total Syntheses of Erythroxylon Alkaloids

This work offers a catalytic approach to convergent ketone assembly based upon formal and tandem C–H insertion of diazoalkanes in the presence of limiting amounts of monomeric formaldehyde, which is easily generated as a gas by thermolysis of the inexpensive and abundant paraformaldehyde (∼30 USD/kg). The method forms di-, tri-, and even tetrasubstituted acetones with high efficiency, and it has streamlined a synthesis of (−)-dihydrocuscohygrine in which the absolute stereochemistry of a proline-based starting material is preserved. Assisted by the advent of new protocols for hydrazone oxidation, we also provide full details on handling non-carbonyl-stabilized diazo compounds.
Pd-catalyzed aryl C-H imidation with arene as the limiting reagent.

An amine-N-oxide-ligated palladium complex, in conjunction with a silver cocatalyst, catalyzes imidation of arenes by the reagent N-fluorobenzenesulfonimide. The reaction enables imidation of a variety of arenes at or below room temperature, requires no coordinating directing group on the substrate, and gives synthetically useful yields with only 1 equiv of arene. Mechanistic data implicate an unusual mechanism devoid of commonly invoked organometallic intermediates: oxidation of the Pd catalyst occurs as the turnover-limiting step, while C–H bond functionalization occurs subsequently at a high oxidation state of the catalyst.
Electron Beam Driven Disordering in Small Particles

Small metal particles in the range of a few nanometers in diameter are seen to progressively disorder when the 100 keV electron beam of a Scanning Transmission Electron Microscope (STEM) is held stationary on the particle. The diffraction pattern of the individual particle is seen to progress from an initial array of indexable diffraction spots to a mixture of diffraction spots and amorphous-like rings and finally to rings with no persistent diffraction spots. After the electron beam is removed, the particles will recrystallize after minutes or hours. Only particles below a critical size are seen to fully disorder. We have observed this in Platinum, Palladium, Rhodium, and Iridium and based on our model of disordering process believe it is a universal effect. It has also been observed with a Platinum Ruthenium alloy. We discuss the mechanism of this disordering and the structure of the resulting disordering particle for the case of Platinum clusters.
The hybrid extended born approximation and CG-FFHT method for axisymmetric media

The authors develop a hybrid implementation of the extended Born approximation (EBA) with the conjugate-gradient fast Fourier Hankel transform (CG-FFHT) method to improve the efficiency of the numerical solution of borehole induction problems in axisymmetric media. First, they use the FFHT to accelerate the EBA as a nonlinear approximation to induction problems, resulting in an algorithm with O(N log/sub 2/ N) arithmetic operations, where N is the number of unknowns in the problem. This accelerated EBA is accurate for most formations encountered in practical applications. Then, for formations with extremely high contrasts, they utilize the accelerated EBA as a partial preconditioner in the CG-FFHT method to solve the problem accurately with few iterations. The seamless combination of these two approaches provides an automatic way toward a general efficient and accurate modeling algorithm for induction measurements in axisymmetric media.
Cloaca, the Most Severe Degree of Imperforate Anus. Experience With 195 Cases

OBJECTIVE: To provide a follow-up of 195 patients with cloacal malformations seen by the author from 1959 to 1998. SUMMARY BACKGROUND DATA: Cloaca, which occurs in approximately 1 of 50,000 births, is the most complex type of imperforate anus with confluence of the rectum, vagina, and bladder in a urogenital sinus. Functional results for the bowel, the genital tract, and the urinary tract were formerly poor. Cloacal exstrophy, which is an even more complex spectrum of malformations, was uniformly fatal until 1960. In addition to imperforate anus, these babies have an omphalocele, two exstrophic bladders, between which there is an open cecum, and a blindly ending colon hanging down in the pelvis from the cecum. Although both of these diagnoses contain the word "cloaca," which is Latin for sewer, they are really two separate entities in terms of surgical management. Cloaca and cloacal exstrophy in most cases are very different anatomic problems. However, there are variants that are like a hybrid, which is the rationale for reporting together an experience with both entities. METHODS: Records were reviewed of 154 patients with cloaca and 41 patients with cloacal exstrophy to assess anorectal function, urinary continence, and sexual function where available. RESULTS: Follow-up was available in 141 cloaca patients: 82 have spontaneous bowel movements and satisfactory control, 38 use enemas to evacuate, 9 have a colostomy, 7 have fecal soiling, and 5 are too recently operated to evaluate. Regarding urinary control, 83 void spontaneously, 40 catheterize to empty, 4 have urinary diversion, 1 has a continent diversion, 5 patients are wet, and 8 are too recently operated to judge. Twenty-four patients are now adults, 17 of who have experienced coitus and 7 have not. Seven have had babies, all except one by cesarean section. Results of surgery for cloacal exstrophy are not as good, but are encouraging nonetheless for an anomaly that was uniformly fatal before 1960. Of the 41 cloacal exstrophy patients being followed, 7 have not undergone surgery. Fifteen have a colostomy; 19 had pull-through of the colon, but 3 were subsequently reversed for fecal incontinence. Most depend on enemas to evacuate. Urinary dryness was attained in 30 patients, usually by intermittent catheterization of the bladder, which was augmented with small bowel or stomach or both. Only three void voluntarily. Fifteen of the completed long-term patients wear no bag. Only three of the completed patients wear two bags. The rest have one bag. CONCLUSIONS: Imperforate anus and associated malformations in cloaca and cloacal exstrophy are not hopeless problems. A reasonable lifestyle can be achieved for most of these children with comprehensive surgical planning.
2D Lyndon Words and Applications

A Lyndon word is a primitive string which is lexicographically smallest among cyclic permutations of its characters. Lyndon words are used for constructing bases in free Lie algebras, constructing de Bruijn sequences, finding the lexicographically smallest or largest substring in a string, and succinct suffix---prefix matching of highly periodic strings. In this paper, we extend the concept of the Lyndon word to two dimensions. We introduce the 2D Lyndon word and use it to capture 2D horizontal periodicity of a matrix in which each row is highly periodic, and to efficiently solve 2D horizontal suffix---prefix matching among a set of patterns. This yields a succinct and efficient algorithm for 2D dictionary matching. We present several algorithms that compute the 2D Lyndon word that represents a matrix. The final algorithm achieves linear time complexity even when the least common multiple of the periods of the rows is exponential in the matrix width.
Evaluating tautological classes using only Hurwitz numbers

Hurwitz numbers count ramified covers of a Riemann surface with prescribed monodromy. As such, they are purely combinatorial objects. Tautological classes, on the other hand, are distinguished classes in the intersection ring of the moduli spaces of Riemann surfaces of a given genus, and are thus "geometric". Localization computations in Gromov-Witten theory provide non-obvious relations between the two. This paper makes one such computation, and shows how it leads to a "master" relation (Theorem 0.1) that reduces the ratios of certain interesting tautological classes to the pure combinatorics of Hurwitz numbers. As a corollary, we obtain a purely combinatorial proof of a theorem of Bryan and Pandharipande, expressing in generating function form classical computations by Faber/Looijenga (Theorem 0.2).
Numerical evaluation of multi-loop integrals using subtraction terms

A formalism for the numerical integration of one- and two-loop integrals is presented. It is based on subtraction terms which remove the soft, collinear and some of the ultraviolet divergences from the integrand. The numerical integral is performed in the Feynman parameter space, using a complex contour deformation to ensure robust convergence even in the presence of physical thresholds. The application of the proposed procedure is demonstrated with several one- and two-loop examples. An implementation in the program nicodemos is publicly available, which currently incorporates only one-loop functionality, but an extension to two-loop cases is planned for future versions.
A Search for OH Megamasers at z > 0.1. III. The Complete Survey

We present the final results from the Arecibo Observatory 1 OH megamaser survey. We discuss in detail the properties of the remaining 18 OH megamasers detected in the survey, including three redetections. We place upper limits on the OH emission from 85 nondetections and examine the properties of 25 ambiguous cases for which the presence or absence of OH emission could not be determined. The complete survey has discovered 50 new OH megamasers (OHMs) in (ultra)luminous infrared galaxies ([U]LIRGs), which doubles the sample of known OHMs and increases the sample at z > 0.1 sevenfold. The Arecibo OH megamaser survey indicates that the OHM fraction in LIRGs is an increasing function of the far-IR luminosity (LFIR) and farIR color, reaching a fraction of roughly 1 in the warmest ULIRGs. Significant relationships between OHMs and their hosts are few, primarily because of a mismatch in size scales of measured properties and an intrinsic scatter in OHM properties roughly equal to the span of the data set. We investigate relationships between OHMs and their hosts with a variety of statistical tools including survival analysis, partial correlation coefficients, and a principal component analysis. There is no apparent OH megamaser ‘‘ fundamental plane.’’ We compile data on all previously known OHMs and evaluate the possible mechanisms and relationships responsible for OHM production in merging systems. The OH-FIR relationship is reexamined by using the doubled OHM sample and found to be significantly flatter than previously thought: LOH / L 1:2� 0:1 FIR . This nearly linear dependence suggests a mixture of saturated and unsaturated masers, either within individual galaxies or across the sample.
Fault tolerance bounds for memory consistency

We analyze the achievable fault tolerances of shared memory consistency conditions in the form of t-resilience, the ability to withstand up to t node failures. We derive tight bounds for linearizability, sequential consistency, processor consistency, and some weaker memories in totally asynchronous systems, in which failed and slow nodes cannot be distinguished. For linearizability, we show that neither the read nor the write operation can tolerate more failures than a minority of the nodes. For sequential consistency, processor consistency, and related conditions, we show that one operation can be wait-free and the other cannot tolerate more failures than a minority of the nodes. Several weaker conditions can have both operations wait-free.
Higgs couplings and precision electroweak data

In light of the discovery of a Higgs-like particle at the LHC, we revisit the status of the precision electroweak data, focusing on two discrepant observables: 1) the long-standing 2.4σ deviation in the forward-backward asymmetry of the bottom quark $ A_{\mathrm{FB}}^b $ , and 2) the 2.3σ deviation in R b , the ratio of the $ Z\ \to\ b\overline{b} $ partial width to the inclusive hadronic width, which is now in tension after a recent calculation including new two-loop electroweak corrections. We consider possible resolutions of these discrepancies. Taking the data at face value, the most compelling scenario is that new physics directly affects $ A_{\mathrm{FB}}^b $ and R b , bringing the prediction into accord with the measured values. We propose a modified ‘Beautiful Mirrors’ scenario which contains new vector-like quarks that mix with the b quark, modifying the $ Zb\overline{b} $ vertex and thus correcting $ A_{\mathrm{FB}}^b $ and R b . We show that this scenario can lead to modifications to the production rates of the Higgs boson in certain channels, and in particular a sizable enhancement in the diphoton channel. We also describe additional collider tests of this scenario.
A safety kernel for traffic light control

The success of kernels for enforcing security in software systems has led to proposals to use kernels for enforcing safety. This paper presents a feasibility demonstration of one particular proposal for a safety kernel via the application of traffic light control. The paper begins with the safety properties for traffic light control and specifies a kernel that maintains the safety properties. An implementation sketch of the kernel in Ada is given and use of the kernel is discussed. The contribution of the paper is a demonstration that a kernel is a feasible and desirable technique for software in a realistic, safety-critical application. The paper also illustrates how formal methods aid the software engineer in constructing and reasoning about such software.
Cohesin-dependent globules and heterochromatin shape 3D genome architecture in S. pombe

Eukaryotic genomes are folded into three-dimensional structures, such as self-associating topological domains, the borders of which are enriched in cohesin and CCCTC-binding factor (CTCF) required for long-range interactions. How local chromatin interactions govern higher-order folding of chromatin fibres and the function of cohesin in this process remain poorly understood. Here we perform genome-wide chromatin conformation capture (Hi-C) analysis to explore the high-resolution organization of the Schizosaccharomyces pombe genome, which despite its small size exhibits fundamental features found in other eukaryotes. Our analyses of wild-type and mutant strains reveal key elements of chromosome architecture and genome organization. On chromosome arms, small regions of chromatin locally interact to form 'globules'. This feature requires a function of cohesin distinct from its role in sister chromatid cohesion. Cohesin is enriched at globule boundaries and its loss causes disruption of local globule structures and global chromosome territories. By contrast, heterochromatin, which loads cohesin at specific sites including pericentromeric and subtelomeric domains, is dispensable for globule formation but nevertheless affects genome organization. We show that heterochromatin mediates chromatin fibre compaction at centromeres and promotes prominent inter-arm interactions within centromere-proximal regions, providing structural constraints crucial for proper genome organization. Loss of heterochromatin relaxes constraints on chromosomes, causing an increase in intra- and inter-chromosomal interactions. Together, our analyses uncover fundamental genome folding principles that drive higher-order chromosome organization crucial for coordinating nuclear functions.
Towards an integrated model of the NIC layered implosions

A detailed simulation-based model of the June 2011 National Ignition Campaign (NIC) cryogenic DT experiments is presented. The model is based on integrated hohlraum-capsule simulations that utilize the best available models for the hohlraum wall, ablator, and DT equations of state and opacities. The calculated radiation drive was adjusted by changing the input laser power to match the experimentally measured shock speeds, shock merger times, peak implosion velocity, and bangtime. The crossbeam energy transfer model was tuned to match the measured time-dependent symmetry. Mid-mode mix was included by directly modeling the ablator and ice surface perturbations up to mode 60. Simulated experimental values were extracted from the simulation and compared against the experiment. The model adjustments brought much of the simulated data into closer agreement with the experiment, with the notable exception of the measured yields, which were 15-40% of the calculated yields.
Development of a high performance heat Sink Based on screen-fin technology

In this paper, a novel high-performance heat sink based on screen-fin technology is described. The structural features of the heat sink are presented. The apparatus to measure both the pressure drop and heat transfer performance are described. Correlation equations of friction factor and Colburn-j factor as a function of screen-fin orientation, coolant properties and flow rate through the mesh are formulated. A semi-empirical model is used to predict the heat exchanger pressure drop, thermal performance and to design prototype heat sinks. Prototypes are built and tested. By screen-fin technology, the best performance of this kind of heat sink with external dimensions: 76.2-mm-wide, 63.5-mm-deep with 38.1-mm-high screen-laminate fins is 4.3W//spl deg/C at 62.3-Pa pressure drop of air flow through the heat sink.
Preparation of TMS protected trifluoromethylated alcohols using trimethylamine N-oxide and trifluoromethyltrimethylsilane (TMSCF3)

Abstract A catalytic trifluoromethylation of aldehydes using trimethylamine N -oxide and trifluoromethyltrimethylsilane (TMSCF 3 ) is described. Aromatic, aliphatic and α,β-unsaturated aldehydes provided good to excellent yields of the corresponding trifluoromethylated products.
Knot Floer homology in cyclic branched covers

In this paper, we introduce a sequence of invariants of a knot K in S : the knot Floer homology groups 1 HFK .†.K/I e K ; i/ of the preimage of K in the m–fold cyclic branched cover over K . We exhibit 1 HFK .†.K/I e K ; i/ as the categorification of a well-defined multiple of the Turaev torsion of †.K/ e K in the case where †.K/ is a rational homology sphere. In addition, when K is a two-bridge knot, we prove that 1 HFK .†.K/I e K ; s0/S1 HFK .SIK/ for s0 the spin Spin structure on †.K/ . We conclude with a calculation involving two knots with identical 1 HFK .SIK; i/ for which 1 HFK .†.K/I e K ; i/ differ as Z2 –graded groups.
Inkjet-printed paper/polymer-based “green” RFID and Wireless Sensor Nodes: The final step to bridge cognitive intelligence, nanotechnology and RF?

In this talk, inkjet-printed flexible antennas, RF electronics and sensors fabricated on paper and other polymer (e.g.LCP)substrates are introduced as a system-level solution for ultra-low-cost mass production of UHF Radio Frequency Identification (RFID) Tags and Wireless Sensor Nodes (WSN) in an approach that could be easily extended to other microwave and wireless applications. The talk will cover examples from UHF up to the millimeter-wave frequency ranges.
The Effect of the Tipped Minimum Wage on Employees in the U.S. Restaurant Industry

According to federal law in 2013, employers can take a credit of up to $5.12 for tips received by workers in satisfying the minimum-wage requirement of $7.25. This article uses interstate variation in laws regarding tip credits and minimum wages to identify the effects of reducing or eliminating the tip credit on employment, hours, and earnings in the U.S. restaurant industry. Using data from the Quarterly Census of Employment and Wages and the Current Population Survey, we find that a reduction in the tip credit increases weekly earnings but reduces employment in the full-service restaurant industry and for tipped workers. The results are robust to controls for spatial heterogeneity in employment trends and are supported by a series of falsification tests.
Controlling the Short-Range Order and Packing Densities of Many-Particle Systems†

Questions surrounding the spatial disposition of particles in various condensed-matter systems continue to pose many theoretical challenges. This paper explores the geometric availability of amorphous many-particle configurations that conform to a given pair correlation function g(r). Such a study is required to observe the basic constraints of non-negativity for g(r) as well as for its structure factor S(k). The hard sphere case receives special attention, to help identify what qualitative features play significant roles in determining upper limits to maximum amorphous packing densities. For that purpose, a five-parameter test family of g’s has been considered, which incorporates the known features of core exclusion, contact pairs, and damped oscillatory short-range order beyond contact. Numerical optimization over this five-parameter set produces a maximumpacking value for the fraction of covered volume, and about 5.8 for the mean contact number, both of which are within the range of previous experimental and simulational packing results. However, the corresponding maximum-density g(r) and S(k) display some unexpected characteristics. These include absence of any pairs at about 1.4 times the sphere collision diameter, and a surprisingly large magnitude for S(k)0), the measure of macroscopic-distance-scale density variations. On the basis of these results, we conclude that restoration of more subtle features to the test-function family of g’s (i.e., a split second peak, and a jump discontinuity at twice the collision diameter) will remove these unusual characteristics, while presumably increasing the maximum density slightly. A byproduct of our investigation is a lower bound on the maximum density for random sphere packings in d dimensions, which is sharper than a well-known lower bound for regular lattice packings for dg 3.
Does whole‐school reform boost student performance? The case of New York City

Thousands of schools around the country have implemented whole-school reform programs to boost student performance. This paper uses quasi-experimental methods to estimate the impact of whole-school reform on students' reading performance in New York City, where various reform programs were adopted in dozens of troubled elementary schools in the mid-1990s. This paper complements studies based on random assignment by examining a broad-based reform effort and explicitly accounting for implementation quality. Two popular reform programs—the School Development Program and Success for All—were not found to significantly increase reading scores but might have been if they had been fully implemented. The More Effective Schools program was found to boost reading scores, but this effect seems to disappear when the program “trainers” leave the school. © 2005 by the Association for Public Policy Analysis and Management.
Three-dimensional simulations of accretion to stars with complex magnetic fields

Disc accretion to rotating stars with complex magnetic fields is investigated using full 3D magnetohydrodynamic (MHD) simulations. The studied magnetic configurations include superpositions of misaligned dipole and quadrupole fields and off-centre dipoles. The simulations show that when the quadrupole component is comparable to the dipole component, the magnetic field has a complex structure with three major magnetic poles on the surface of the star and three sets of loops of field lines connecting them. A significant amount of matter flows to the quadrupole 'belt', forming a ring-like hotspot on the star. If the maximum strength of the magnetic field on the star is fixed, then we observe that the mass accretion rate, the torque on the star and the area covered by hotspots are several times smaller in the quadrupole-dominant cases than in the pure dipole cases. The influence of the quadrupole component on the shape of the hotspots becomes noticeable when the ratio of the quadrupole and dipole field strengths Bq /B d ≥ 0.5. It becomes dominant in determining the shape of the hotspots when Bq /B d ≥ 1. We conclude that if the quadrupole component is larger than the dipole one, then the shape of the hotspots is determined by the quadrupole field component. In the case of an off-centre dipole field, most of the matter flows through a one-armed accretion stream, forming a large hotspot on the surface, with a second much smaller secondary spot. The light curves may have simple, sinusoidal shapes, thus mimicking stars with pure dipole fields. Or, they may be complex and unusual. In some cases, the light curves may be indicators of a complex field, in particular if the inclination angle is known independently. We also note that in the case of complex fields, magnetospheric gaps are often not empty, and this may be important for the survival of close-in exosolar planets.
Time-dependent thermal blooming in axial pipe flow.

The temperature and optical path differences are found for the time-dependent conduction equation with axial convection for an arbitrary heat source. The solution satisfies Dirichlet boundary conditions in the radial and axial directions.
Major solar eruptions and high-energy particle events during solar cycle 24

We report on a study of all major solar eruptions that occurred on the frontside of the Sun during the rise to peak phase of cycle 24 (first 62 months) in order to understand the key factors affecting the occurrence of large solar energetic particle events (SEPs) and ground level enhancement (GLE) events. The eruptions involve major flares with soft X-ray peak flux ≥ 5.0 x10−5 Wm−2 (i.e., flare size ≥ M5.0) and accompanying coronal mass ejections (CMEs). The selection criterion was based on the fact that the only front-side GLE in cycle 24 (GLE 71) had a flare size of M5.1. Only approximately 37% of the major eruptions from the western hemisphere resulted in large SEP events. Almost the same number of large SEP events was produced in weaker eruptions (flare size < M5.0), suggesting that the soft X-ray flare is not a good indicator of SEP or GLE events. On the other hand, the CME speed is a good indicator of SEP and GLE events because it is consistently high supporting the shock acceleration mechanism. We found the CME speed, magnetic connectivity to Earth (in longitude and latitude), and ambient conditions as the main factors that contribute to the lack of high-energy particle events during cycle 24. Several eruptions poorly connected to Earth (eastern-hemisphere or behind-the-west-limb events) resulted in very large SEP events detected by the Solar Terrestrial Relations Observatory (STEREO) spacecraft. Some very fast CMEs, likely to have accelerated particles to GeV energies, did not result in a GLE event because of poor latitudinal connectivity. The stringent latitudinal requirement suggests that the highest-energy particles are likely accelerated in the nose part of shocks, while the lower energy particles are accelerated at all parts. There were also well-connected fast CMEs, which did not seem to have accelerated high-energy particles due to possible unfavorable ambient conditions (high Alfven speed, overall reduction in acceleration efficiency in cycle 24).
Discovering mappings in hierarchical data from multiple sources using the inherent structure

Unprecedented amounts of media data are publicly accessible. However, it is increasingly difficult to integrate relevant media from multiple and diverse sources for effective applications. The functioning of a multimodal integration system requires metadata, such as ontologies, that describe media resources and media components. Such metadata are generally application-dependent and this can cause difficulties when media needs to be shared across application domains. There is a need for a mechanism that can relate the common and uncommon terms and media components. In this paper, we develop an algorithm to mine and automatically discover mappings in hierarchical media data, metadata, and ontologies, using the structural information inherent in these types of data. We evaluate the performance of this algorithm for various parameters using both synthetic and real-world data collections and show that the structure-based mining of relationships provides high degrees of precision.
Synthesis of functionalized non-natural amino acid derivatives via amidoalkylation transformations

Synthetic routes have been developed for the preparation of functionalized amino acid derivatives in which the α-substituent at carbon 2 is either an aromatic or a heteroaromatic group. The α-substituent was introduced using an amidoalkylation reaction using boron trifluoride etherate and proceeded in moderate yield with excellent regioselectivity. This protocol permitted the employment of the acid sensitive heterocycles: pyrrole, benzofuran, and indole. The scope and limitations of this procedure have been evaluated.
Affine Demazure modules and T-fixed point subschemes in the affine Grassmannian

Let G be a simple algebraic group defined over C and T be a maximal torus of G. For a dominant coweight λ of G, the T-fixed point subscheme [formula] of the Schubert variety [formula] in the affine Grassmannian GrG is a finite scheme. We prove that for all such λ if G is of type A or D and for many of them if G is of type E, there is a natural isomorphism between the dual of the level one affine Demazure module corresponding to λ and the ring of functions (twisted by certain line bundle on GrG) of [formula]. We use this fact to give a geometrical proof of the Frenkel–Kac–Segal isomorphism between basic representations of affine algebras of A, D, E type and lattice vertex algebras.
The Relationship of Transient Upper-Level Troughs to Variability of the North American Monsoon System

Relationships between transient upper-tropospheric troughs and warm season convective activity over the southwest United States and northern Mexico are explored. Analysis of geopotential height and vorticity fields from the North American Regional Reanalysis and cloud-to-ground lightning data indicates that the passage of mobile inverted troughs (IVs) significantly enhances convection when it coincides with the peak diurnal cycle (1800‐0900 UTC) over the North American monsoon (NAM) region. The preferred tracks of IVs during early summer are related to the dominant modes of Pacific sea surface temperature (SST) var
OPTIMAL MANDATES AND THE WELFARE COST OF ASYMMETRIC INFORMATION: EVIDENCE FROM THE U.K. ANNUITY MARKET

Much of the extensive empirical literature on insurance markets has focused on whether adverse selection can be detected. Once detected, however, there has been little attempt to quantify its welfare cost or to assess whether and what potential government interventions may reduce these costs. To do so, we develop a model of annuity contract choice and estimate it using data from the U.K. annuity market. The model allows for private information about mortality risk as well as heterogeneity in preferences over different contract options. We focus on the choice of length of guarantee among individuals who are required to buy annuities. The results suggest that asymmetric information along the guarantee margin reduces welfare relative to a first-best symmetric information benchmark by about £127 million per year or about 2 percent of annuitized wealth. We also find that by requiring that individuals choose the longest guarantee period allowed, mandates could achieve the first-best allocation. However, we estimate that other mandated guarantee lengths would have detrimental effects on welfare. Since determining the optimal mandate is empirically difficult, our findings suggest that achieving welfare gains through mandatory social insurance may be harder in practice than simple theory may suggest.
Preparation of 2-hydroxybenzamidines from 3-aminobenzisoxazoles

Abstract 2-Hydroxybenzamidines have been prepared from 3-aminobenzisoxazoles by reductive cleavage of the nitrogen–oxygen bond using catalytic hydrogenation, Zn/AcOH or NiCl 2 /NaBH 4 . This ring-opening reaction can be accomplished chemoselectively in the presence of a variety of hydrogenation-sensitive functional groups including an aryl bromide, benzyl carbamate, and olefin.
Using Behavioral Economics to Show the Power and Efficiency of Corporate Law as Regulatory Tool

Prepared for the Daniel J. Dykstra Corporate Governance Symposium at University of California, Davis, in February 2001, this article argues that changes in corporate governance in the United States - specifically the relaxation of the profit maximization norm, the broadening of management's fiduciary duties to include workers, and the inclusion of worker representatives on boards of directors - are likely to be efficient means of reaching certain preferred policy outcomes, such as an increase in the wages of working people and a decrease in income inequality. Instead of being seen as "private law," corporate law should be regarded as a regulatory tool and judged on that basis. Thus, rather than focusing on whether changes in corporate governance would be beneficial or harmful to the firm, the discussion should take account of the likelihood that certain changes in corporate governance, even if costly to shareholders, might nevertheless be on net socially beneficial. Moreover, because of the nature of the changes proposed, there is reason to believe that the suggested adjustments in corporate governance are not only powerful in achieving certain policy goals but also relatively efficient in achieving them. This paper will use insights from behavioral economics to advance these arguments.
Three kinds of ethics for three kinds of engineering

The phenomenon of the engineering enterprise stands within a web of contextual relationships, and the elements of (1) the engineer, (2) engineering and (3) the engineered stand out as fundamental to the engineering enterprise. Each element is contextual in the sense of being integrated into a more or less coherent realm of discourse consisting of thoughts, actions, words, things, roles and goals. That realm of discourse indicates the contexts that condition and are conditioned by the engineering enterprise. Corresponding to each of the three elements of the engineering enterprise is an appropriate and distinct type of ethics. (1) Virtue ethics is appropriate to the engineer who engineers the engineered. It asks how the engineer can be good in a moral sense. (2) Conceptual ethics is appropriate to engineering, which aims at the production of the engineered and requires the engagement of engineers. It asks how engineers can do good engineering. (3) Material ethics is appropriate to the engineered, which follows from the engineering process via the efforts of the engineer. It asks how engineering can make products that contribute to the common good in a convivial society. Being, doing and making are all bound up in the statement "The engineer engineers the engineered". We cannot separate the engineer, engineering and the engineered, either from each other or from the contexts in which they are embedded, but we can distinguish them, and with each we can associate a different kind of ethics.
Quantum Gravity in 2 + 1 Dimensions: The Case of a Closed Universe

In three spacetime dimensions, general relativity drastically simplifies, becoming a "topological" theory with no propagating local degrees of freedom. Nevertheless, many of the difficult conceptual problems of quantizing gravity are still present. In this review, I summarize the rather large body of work that has gone towards quantizing (2 + 1)-dimensional vacuum gravity in the setting of a spatially closed universe.
Voltage Synthesis Using Dual Virtual Quadrature Sources—A New Concept in AC Power Conversion

Controlling an ac voltage often involves changing the amplitude, phase, and/or harmonic content of the voltage. This can require the addition of voltage at or around the zero crossing of the available ac voltage. Synthesis of this additional voltage normally requires an ac or dc source (or energy storage element) from which the desired voltage can be synthesized using pulsewidth modulation techniques. This paper proposes a novel concept wherein dual virtual quadrature sources are used to synthesize the required additional voltage. This is seen to result in simple low-cost ac converters that are robust, have minimal component count, and can realize phase shift and/or harmonic control without requiring multiple sources or energy-storage elements. The approach is seen to have simple implementation and can realize potentially useful devices such as controllable transformers and inverter-less active filters.