cssi/SciSciGPT-SciSciNet huggingface dataset:
Jumps in cohomology and free group actions

A discrete group G has periodic cohomology over R if there is an element in a cohomology group cup product with which it induces an isomorphism in cohomology after a certain dimension. Adem and Smith showed that if R=Z, then this condition is equivalent to the existence of a finite dimensional free-G-CW-complex homotopy equivalent to a sphere. It has been conjectured by Olympia Talelli, that if G is also torsion-free then it must have finite cohomological dimension. In this paper we use the implied condition of jump cohomology over R to prove the conjecture for HF-groups and solvable groups. We also find necessary conditions for free and proper group actions on finite dimensional complexes homotopy equivalent to closed, orientable manifolds.
What Does Clustering Tell Us About the Buildup of the Red Sequence

We analyze the clustering of red and blue galaxies from four samples spanning a redshift range of 0.4 < z < 2.0 to test the various scenarios by which galaxies evolve onto the red sequence. The data are taken from the UKIDSS Ultra Deep Survey, DEEP2, and COMBO-17. The use of clustering allows us to determine what fraction of the red sequence is made up of central galaxies and satellite galaxies. At all redshifts, including z = 0, the data are consistent with ~60% of satellite galaxies being red or quenched, implying that ~1/3 of the red sequence is comprised of satellite galaxies. More than three-fourths of red satellite galaxies were moved to the red sequence after they were accreted onto a larger halo. The constant fraction of satellite galaxies that are red yields a quenching time for satellite galaxies that depends on redshift in the same way as halo dynamical times: t Q ~ (1 + z)–1.5. In three of the four samples, the data favor a model in which red central galaxies are a random sample of all central galaxies; there is no preferred halo mass scale at which galaxies make the transition from star-forming to red and dead. The large errors on the fourth sample inhibit any conclusions. Theoretical models in which star formation is quenched above a critical halo mass are excluded by these data. A scenario in which mergers create red central galaxies imparts a weaker correlation between halo mass and central galaxy color, but even the merger scenario creates tension with red galaxy clustering at redshifts above 0.5. These results suggest that the mechanism by which central galaxies become red evolves from z = 0.5 to z = 0.
Solidification reactions in undercooled alloys

Abstract It is now recognized that rapid solidification conditions can be achieved with slow cooling rates provided that the liquid is undercooled substantially prior to nucleation. In fact, many of the novel metastable microstructures produced by rapid solidification require the consideration of an undercooled liquid for analysis. In general, rapid solidification techniques involve either constrained growth in which the solid phase formation is limited by the rate of heat extraction or delayed nucleation of the solid followed by unconstrained growth. With delayed nucleation methods such as the droplet emulsion technique direct measurement of undercooling is available for analysis of metastable phase formation. In fine droplet samples an effective nucleation isolation allows for undercoolings of about 0.3 T m with a limit taht is usually set by heterogeneous nucleation. Processing variables can be used to control the undercooling and produce a transition in solidification reactions. In this case the use of metastable phase diagrams is important for the analysis of product structures and pathways during solidification and solid state treatments. A key to the understanding of structural evolution is the consideration of competitive nucleation and growth kinetics and thermal history, which can also provide a model for control of solidification reactions as demonstrated in selective alloys.
Topology of the future chronological boundary: universality for spacelike boundaries

A method is presented for imputing a topology for any chronological set, i.e. a set with a chronology relation, such as a spacetime or a spacetime with some sort of boundary. This topology is shown to have several good properties, such as replicating the manifold topology for a spacetime and replicating the expected topology for some simple examples of spacetime-with-boundary; it also allows for a complete categorical characterization, in topological categories, of the future causal boundary construction of Geroch, Kronheimer and Penrose (GKP), showing that construction to have a universal property for future-completing chronological sets with spacelike boundaries. Rigidity results are given for any reasonable future-completion of a spacetime, in terms of the GKP boundary: in the imputed topology, any such boundary must be homeomorphic to the GKP boundary (if all points have indecomposable pasts) or to a topological quotient of a closely related boundary (if boundaries are spacelike). A large class of warped-product-type spacetimes with spacelike boundaries is examined, calculating the GKP and other possible boundaries and showing that the imputed topology gives the expected results; included among these are the Schwarzschild singularity and those Robertson-Walker singularities which are spacelike.
Laser Assisted Seeding for Electroless Plating on Insulators

Excimer laser pulses with wavelengths of 248 and 308 nm were used to selectively seed Pd on SiO2 surfaces, making them suitable for electroless plating. This novel seeding process for insulating materials is accomplished with the sample immersed in the seeding solution, and occurs only on the areas of the substrate that are illuminated (through the liquid) by the laser light. The Pd content of the seeded samples increased with the number of pulses, but was rather independent of repetition rate. The deposition rate showed a dependence with wavelength consistent with a defect driven mechanism for electron excitation through the band gap of SiO2. These electrons then reduce the Pd ions in the solution in contact with the surface.
Spin Hecke algebras of finite and affine types

We introduce the spin Hecke algebra, which is a q-deformation of the spin symmetric group algebra, and its affine generalization. We establish an algebra isomorphism which relates our spin (affine) Hecke algebras to the (affine) Hecke?Clifford algebras of Olshanski and Jones?Nazarov. Relation between the spin (affine) Hecke algebra and a nonstandard presentation of the usual (affine) Hecke algebra is displayed, and the notion of covering (affine) Hecke algebra is introduced to provide a link between these algebras. Various algebraic structures for the spin (affine) Hecke algebra are established.
Forging Fiscal Reform: Constitutional Change, Public Policy, and the Creation of Administrative Capacity in Wisconsin, 1880-1920

At the turn of the twentieth century, Wisconsin, like many northern industrial states, faced a profound fiscal challenge. As one concerned citizen succinctly explained, “The two great administrative problems before our people at this time are, first, the control of corporate wealth, and, second, the establishment of a rational system of taxation.” The large-scale structural pressures created by the rise of corporate capitalism and the decline of an obsolete tax system forced all levels of government to reexamine the substance and administration of their fiscal policies. At the state and local level, many governments addressed the mismatch between the increasing demand for state services and the declining supply of revenue by turning to new levies and innovative forms of administration.
A modified light transmission visualization method for DNAPL saturation measurements in 2-D models

Abstract In this research, a light transmission visualization (LTV) method was used to quantify dense non-aqueous phase liquids (DNAPL) saturation in two-dimensional (2-D), two fluid phase systems. The method is an expansion of earlier LTV methods and takes into account both absorption and refraction light theories. Based on this method, DNAPL and water saturations can rapidly be obtained point wise across sand-packed 2-D flow chambers without the need to develop a calibration curve. A single point calibration step is, however, needed when dyed DNAPL is used to account for the change in the transmission factor at the dyed DNAPL–water interface. The method was applied to measure, for the first time, undyed DNAPL saturation in small 2-D chambers. Known amounts of DNAPL, modeled by tetrachloroethylene (PCE), were added to the chamber and these amounts were compared to results obtained by this LTV method. Strong correlation existed between results obtained based on this method and the known PCE amounts with an R2 value of 0.993. Similar experiments conducted using dyed PCE showed a stronger correlation between results obtained by this LTV method and the known amounts of dyed PCE added to the chamber with an R2 value of 0.999. The method was also used to measure dyed PCE saturation in a large 2-D model following sparging experiments. Results obtained from image analyses following each sparging event were compared to results obtained by two independent techniques, namely gas chromatography–mass spectrometry (GC/MS) analyses and carbon column extraction. There was a good agreement between the results obtained by this LTV method and those obtained by the two independent techniques when experiments were carried out under stable light source conditions and errors in mass balance were minor. The method presented here can be expanded to measure fluid contents in three fluid phase systems and provide a non-destructive, non-intrusive tool to investigate changes in DNAPL architecture and flow characteristics in laboratory experiments.
Dynamical percolation on general trees

Haggstrom et al. (Ann Inst H Poincare Probab Stat 33(4):497–528, 1997) have introduced a dynamical version of percolation on a graph G. When G is a tree they derived a necessary and sufficient condition for percolation to exist at some time t. In the case that G is a spherically symmetric tree (Peres and Steif in Probab Theory Relat Fields 111(1):141–165, 1998), derived a necessary and sufficient condition for percolation to exist at some time t in a given target set D. The main result of the present paper is a necessary and sufficient condition for the existence of percolation, at some time $${t\in D}$$ , in the case that the underlying tree is not necessary spherically symmetric. This answers a question of Yuval Peres (personal communication). We present also a formula for the Hausdorff dimension of the set of exceptional times of percolation.
The production and acceleration of radioactive ion beams at the HRIBF

The Holifield Radioactive Ion Beam Facility (HRIBF) includes a K=100 cyclotron (ORIC) which provides high-intensity light-ions for producing radioactive atoms, and a 25 MV tandem electrostatic accelerator which is used to accelerate the radioactive-ions for nuclear structure and nuclear astrophysics research. Ion sources and targets suitable for the production of various radioactive ion beams (RIBs) have been developed. Operational experiences, problem areas, and plans for future beam development are discussed.
Testing Commitment Models of Monetary Policy: Evidence from OECD Economies

In∞ation rates in a number of OECD follow a common trend over the past four decades: in∞ation starts out low in the 1960s, rises for a time before peaking in the 1970s or early 1980s, and then falls back to initial levels. This similarity in the behavior of trend in∞ation suggests that any explanation of long run in∞ation trends ought to apply across OECD countries. Ireland (1999) shows that a simple time inconsistency model of monetary policy, modifled to allow for a time-varying NAIRU, can explain long run trends in U.S. in∞ation. In this paper we show that this result cannot serve as an explanation of the common trend in OECD in∞ation, as it flts the data only in the U.S.. We investigate two important variants of the hypothesis: i) that time inconsistency was an important component of central bank behavior in earlier decades, but has become less signiflcant in recent years, and ii) that time inconsistency problems drive U.S. in∞ation, which afiects in∞ation rates in other countries as a result of central bankers’ attempts to manage nominal exchange rate movements vis a vis the U.S. dollar. We flnd that the flrst hypothesis flts the data no better than the baseline model. We flnd some support for the international spillovers version of the model, but the behavior of non-U.S. central bankers with respect to domestic unemployment rates is not well described by the time inconsistency mechanism.
Subword complexes in Coxeter groups

Abstract Let ( Π , Σ ) be a Coxeter system. An ordered list of elements in Σ and an element in Π determine a subword complex , as introduced in Knutson and Miller (Ann. of Math. (2) (2003), to appear). Subword complexes are demonstrated here to be homeomorphic to balls or spheres, and their Hilbert series are shown to reflect combinatorial properties of reduced expressions in Coxeter groups. Two formulae for double Grothendieck polynomials, one of which appeared in Fomin and Kirillov (Proceedings of the Sixth Conference in Formal Power Series and Algebraic Combinatorics, DIMACS, 1994, pp. 183–190), are recovered in the context of simplicial topology for subword complexes. Some open questions related to subword complexes are presented.
Fermions in a global monopole background

Abstract We study the scattering of fermions in a “global monopole” background metric. This is the four-dimensional analogue of the scattering on a cone in three dimensions. The scattering amplitude is exactly obtained. We then study massless fermion-dyon systems in such a background metric. The density of the S -wave fermion condensate is found to be given by a constant times the flat space value of Callan and Rubakov.
Spatiotemporal Dissociation of Brain Activity Underlying Subjective Awareness, Objective Performance and Confidence

Despite intense recent research, the neural correlates of conscious visual perception remain elusive. The most established paradigm for studying brain mechanisms underlying conscious perception is to keep the physical sensory inputs constant and identify brain activities that correlate with the changing content of conscious awareness. However, such a contrast based on conscious content alone would not only reveal brain activities directly contributing to conscious perception, but also include brain activities that precede or follow it. To address this issue, we devised a paradigm whereby we collected, trial-by-trial, measures of objective performance, subjective awareness, and the confidence level of subjective awareness. Using magnetoencephalography recordings in healthy human volunteers, we dissociated brain activities underlying these different cognitive phenomena. Our results provide strong evidence that widely distributed slow cortical potentials (SCPs) correlate with subjective awareness, even after the effects of objective performance and confidence were both removed. The SCP correlate of conscious perception manifests strongly in its waveform, phase, and power. In contrast, objective performance and confidence were both contributed by relatively transient brain activity. These results shed new light on the brain mechanisms of conscious, unconscious, and metacognitive processing.
Thermal structures - Four decades of progress

Since the first supersonic flight in October 1947, the United States has designed, developed and flown flight vehicles within increasingly severe aerothermal environments. Over this period, major advances in engineering capabilities have occurred that will enable the design of thermal structures for high speed flight vehicles in the twenty-first century. Progress in thermal-structures is surveyed for the last four decades to provide a historical perspective for future efforts.
Maximal tori in the contactomorphism groups of circle bundles over Hirzebruch surfaces

In a recent preprint Yael Karshon showed that there exist non-conjugate tori in a group of symplectomorphisms of a Hirzebruch surface. She counted them in terms of the cohomology class of the symplectic structure. We show that a similar phenomenon exists in the contactomorphism groups of pre-quantum circle bundles over Hirzebruch surfaces. Note that the contact structures in question are fillable. This may be contrasted with an earlier paper where we showed that there are infinitely many non-conjugate tori in the contactomorphism groups of certain overtwisted lens spaces (Contact cuts, Israel J. Math, 124(2001), 77--92).
High accuracy gaseous X-ray detectors

Abstract An outline is given of the design and operation of high accuracy position-sensitive X-ray detectors suitable for experiments using synchrotron radiation. They are based on the gas proportional detector, with position readout using a delay line; a detailed examination is made of factors which limit spatial resolution. Individual wire readout may be used for extremely high counting rates.
Crafting Hyperreal Spaces for Comic Insights: The Onion News Network's Ironic Iconicity

In 2007, the flagship humor publication, The Onion, launched the Onion News Network (ONN), a comic news organization producing online sketch videos. This article argues that ONN is a distinctive form of hyperreal social critique that uses ironic iconicity, rather than slapstick or the usual tomfoolery of much comedy programming, to invite rhetorical insights about contemporary media events and political practices. ONN's videos draw attention toward communicative dynamics, creating spaces for alternative civic understandings through a televisual technique that imitates but also reconfigures the structure, delivery, or content of mainstream news broadcasts like CNN and Fox News. Although not without limitations, this ironic iconicity crafts a multimodal online rhetoric and demonstrates the contingency, recursivity, and judgment of news communication norms and practices.
Heterotic kink solitons and their worldvolume action

We present a formalism for computing the higher-order corrections to the worldvolume action of a co-dimension one kink soliton embedded in five-dimensional het- erotic M-theory. The geometry of heterotic M-theory, as well as the effective theory which describes a five-brane wrapping a holomorphic curve by a topological kink in a scalar field, is reviewed. Using this formalism, the explicit worldvolume action is computed to second order in two expansion parameters — one describing the "warp" of the heterotic geometry and the second the fluctuation length of the soliton hypersurface. The result is expressed in terms of the trace of the extrinsic curvature and the intrinsic curvature scalar.
Pullback attractors for the non-autonomous FitzHugh-Nagumo system on unbounded domains

Abstract The existence of a pullback attractor is established for the singularly perturbed FitzHugh–Nagumo system defined on the entire space R n when external terms are unbounded in a phase space. The pullback asymptotic compactness of the system is proved by using uniform a priori estimates for far-field values of solutions. Although the limiting system has no global attractor, we show that the pullback attractors for the perturbed system with bounded external terms are uniformly bounded, and hence do not blow up as a small parameter approaches zero.
On the Uniqueness of Classical Semiconjugations for Self-Maps of the Disk

We study the uniqueness properties of classical semiconjugations for analytic self-maps of the disk, by characterizing them as canonical solutions to certain functional equations. As a corollary, we obtain a complete description of all possible solutions to such equations.
In situ study of effects of ion irradiation on solid-state crystallization of cobalt disilicide thin films

Abstract Results of a continuing in situ study of the ion-irradiation-modified crystallization of amorphous CoSi2 thin films are discussed. 1.5 MeV Kr ion irradiation is employed at 90 K to “mix” nominally amorphous, as deposited material for subsequent epitaxial regrowth at 450 K. The ion irradiation is also employed at 300 K to produce ion-assisted crystallization. The average degree of transformation per ion is approximately 4 x 10-20 cm3. The resultant number density of crystals, however, depends sensitively on prior treatment of the film. For example, 300 kV electron irradiation at 300 K prior to ion irradiation may result in a large number density of crystal nuclei. Low-dose Kr irradiation at 300 K may also cause a slight increase in the number density of crystals formed subsequently at 450 K, while larger Kr doses at 300 K ( > 3 X 1014 cm-2) may double the subsequent thermal growth rate at 450 K. These results are discussed qualitatively in terms of nucleation and growth theory.
An efficient algorithm for clustering of large-scale mass spectrometry data

High-throughput spectrometers are capable of producing data sets containing thousands of spectra for a single biological sample. These data sets contain a substantial amount of redundancy from peptides that may get selected multiple times in a LC-MS/MS experiment. In this paper, we present an efficient algorithm, CAMS (Clustering Algorithm for Mass Spectra) for clustering mass spectrometry data which increases both the sensitivity and confidence of spectral assignment. CAMS utilizes a novel metric, called F-set, that allows accurate identification of the spectra that are similar. A graph theoretic framework is defined that allows the use of F-set metric efficiently for accurate cluster identifications. The accuracy of the algorithm is tested on real HCD and CID data sets with varying amounts of peptides. Our experiments show that the proposed algorithm is able to cluster spectra with very high accuracy in a reasonable amount of time for large spectral data sets. Thus, the algorithm is able to decrease the computational time by compressing the data sets while increasing the throughput of the data by interpreting low S/N spectra.
Knowledge-based spatial differences in economic activity, job related migration and housing related migration

This paper analyzes the mutual effects of growth of cities and migration between cities. A model in which cities manufacture goods in a traditional sector and in a technological sector, and each city exhibits independently learning-by-doing in the latter sector is presented. The possibility that the development of one city prevents the development of the other is demonstrated. The higher wage in the developed city attracts the talented residents of the less developed city, to which less talented residents migrate in search of lower housing prices, thus creating bi-directional migration that reinforces the above result. An empirical analysis of the differences between job-related migration and housing-related migration in the U.S. is conducted, finding that these two streams are indeed in-line with the model’s prediction. Implications for regional development policies are discussed.
Continuous proteolytic therapy for decubitus ulcers.

Abstract The physiologic elements, hematologic and nutritive, which support normal wound healing are almost inevitably in subnormal supply at the site of a decubitus ulcer. The objective of local treatment should be to assure optimal availability of this reduced supply to the tissues by maintaining the integrity of the capillary and lymphatic systems. The following factors inhibit local circulation and drainage: (1) necrotic tissue and purulent debris, (2) capillary blockage caused by fibrin thrombi or agglutinated erythrocytes, and (3) a barrier of excessive collagen frequently laid down in slow healing lesions. An ointment combining the proteolytic agents, papain and urea, with the antiagglutinin, sodium copper chlorophyllin, provides a practical means of maintaining normal circulation and drainage in decubitus ulcers. The inflammatory effects ordinarily associated with the products of enzymatic digestion are controlled by the chlorophyllin content and continuous, prolonged use of the proteolytic ointment is thereby made possible. A clinical trial is reported involving decubitus ulcers in thirty elderly mental patients treated with daily dressings of the papain-urea-chlorophyllin ointment. Complete healing was obtained in twenty-seven patients in from two to six weeks. The proteolytic ointment accomplished complete debridement of the ulcers in from three to five days, and thereafter the lesions remained clean with progressive granulation until healed. No evidence of irritation or sensitization was noted. Results obtained in decubitus ulcers with the papain-urea-chlorophyllin ointment are superior to any observed by us previously in the treatment of this condition. It is our impression that continuous proteolytic therapy, as exemplified by this preparation, represents a distinct advance in the local treatment of resistant lesions.
Neural Networks for Inverse Problems in Damage Identification and Optical Imaging

Artie cial neural networks (ANNs) are employed in solving inverse problems in damage detection in structures, as well as detection, using optical imaging, of an anomaly in a light-diffusive media, such as a human tissue. Both of these problems, namely, identifying the damage parameters in a damaged structure and identifying the representative properties in a tissue, require solving highly complex inverse problems. The neural networks (NNs) for both problems are similar, and a method found suitable for solving one type of problem can be applied for solving the other type of problem. In the damage identie cation problem, the natural frequencies of a damaged beam model obtained from analytical and numerical methods were used to identify damage parameters by employing feedforward backpropagation, and also radial basis NNs. In the optical imaging problem, the tissue under investigation was illuminated by a number of near-infrared light sources placed around the circumference of the tissue. Both the location and the size of the anomaly were identie ed by studying the ine uence of the anomaly on the light intensity received at the boundary of the tissue. The near-infrared light measurements are assumed to be available at a number of light detector positions, also along the circumference of the tissue. NNs were used to determine the location and the size of the anomaly in a tissue. The direct problem for the case of optical imaging was solved using the e nite element method to generate the training and testing sets for NNs.
A hybrid approach toward model-based texture segmentation

Abstract A hybrid texture segmentation algorithm, combining statistical ( maximum likelihood/maximum a posteriori ) and structural ( local consensus ) classification techniques, is developed. This algorithm exhibits several advantages over traditional algorithms based solely on statistical models: (i) homogeneity and integrity of each region in the texture mosaic can be included implicitly by a local voting scheme, in addition to explicit modelling through Gibbs random fields, (ii) modified maximum likelihood solution of hybrid segmentation algorithm provides a better initial estimate of region boundaries which can be used in a maximum a posteriori segmentation algorithm. With this initial estimate, an iterative, semi-deterministic relaxation algorithm, called mean field annealing , is used to locate the nearly global optimum solution efficiently. The results indicate that the hybrid model provides better immunity to misclassification than the traditional single pixel window-based classification approaches.
Analysis and characterization of package resonance

This article presents FDTD analysis and prediction of the overall effects of the resonance in ceramic and plastic packages. Practical structures that result in strong resonance effects are investigated, such as coupled cross lines with a via transition and multiple via transitions on a single line. A detailed study of the mutual coupling, including resonance effects, is also performed and presented. The results of the analysis indicate that the package performance can be very sensitive to the resonance effects. A broadband equivalent-circuit model for multiple transition discontinuities (two via holes) on a single line has been developed and presented. Good agreement between the frequency response of the FDTD and the circuit models has been achieved over a broad band of frequencies. The analysis presented in this article provides insight about the limits at which coupling effects on the overall package performance can be neglected. The equivalent-circuit model presented in this article can greatly simplify the analysis and simulation of a complex package, including several transition discontinuities, assuming that the coupling is small. © 2004 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2005.
The concept of resilience: retrospect and prospect

The modern study of stability in ecology can be said to have begun with the appearance of ‘Fluctuations of Animal Populations and a Measure of Community Stability’, by R.H. MacArthur in 1955. Since the publication of this influential paper, ecologists have investigated the properties of a number of different stability and stability-related concepts; the concepts of persistence, resilience, resistance, and variability readily come to mind. Of these various concepts, the concept of resilience itself appears to have been rather resilient. Indeed, as Neubert and Caswell (1997) and others have noted, today there is a vast literature on resilience. However, it is important to note that this literatur—to the best of my knowledge—has been primarily ecological in nature. In other words, the concept of resilience originated in ecology, and this concept has been applied and studied primarily in the context of ecosystems.
Partisan Polarization and Blame Attribution in a Federal System: The Case of Hurricane Katrina

When multiple government authorities at overlapping levels of administration fail to do their jobs properly, whom do citizens hold responsible? People can potentially make more accurate judgments by taking into account the roles and responsibilities of the officials involved. However, if party identification plays a major role in shaping Americans' attitudes on federalism, such information may potentially lead to even greater partisan polarization. This article explores these questions using a controlled experiment in which citizens were provided job titles of government officials involved in the poor response to Hurricane Katrina. Both Republican and Democratic citizens update their blame attributions in the same direction in response to new information. Despite polarized general attitudes on federalism, partisans do not polarize further when using specific information. Copyright 2008, Oxford University Press.
Photochemistry of molecular systems for optical 3D storage memory

The photochemistry, kinetics and spectra of several spiropyran molecules have been studied. The transient species of the photochromic reactions and precursors have been identified and the rate of formation and decay measured. We also present means for the utilization of spiropyrans in writing and accessing information in 3D volume optical memory.
A Simple Multifunction Discriminator for Multichannel Triggers

A simple version of a multifunction timing discriminator using only two integrated circuits is presented. It can be configured as a leading edge, a constant fraction, a zero cross or a dual threshold timing discriminator. Since so few parts are used, it is well suited for building multichannel timing discriminators. Two versions of this circuit are described: a quadruple multifunction discriminator and an octal constant fraction trigger. The different compromises made in these units are discussed. Results for walk and jitter obtained with these are presented and possible improvements are discussed.
Experiments on the Richtmyer-Meshkov Instability with an Imposed, Random Initial Perturbation

A vertical shock tube is used to perform experiments on the Richtmyer–Meshkov instability with a three-dimensional random initial perturbation. A membraneless flat interface is formed by opposed gas flows in which the light and heavy gases enter the shock tube from the top and from the bottom of the shock tube driven section. An air/SF $$_{6}$$ gas combination is used and a Mach number $$ M = 1.2$$ incident shock wave impulsively accelerates the interface. Initial perturbations on the interface are created by vertically oscillating the gas column within the shock tube to produce Faraday waves on the interface resulting in a short wavelength, three-dimensional perturbation. Planar Mie scattering is used to visualize the flow in which light from a laser sheet is scattered by smoke seeded in the air, and image sequences are captured using three high-speed video cameras. Measurements of the integral penetration depth prior to reshock show two growth behaviors, both having power law growth with growth exponents in the range found in previous experiments and simulations. Following reshock, all experiments show very consistent linear growth with a growth rate in good agreement with those found in previous studies.
Race, Sex, and the Neglected Risks for Women and Girls in Sub-Saharan Africa

Abstract Global AIDS policy has failed to stop the spread of HIV in sub-Saharan Africa because prevention programs are limited by an unscientific theory of disease causation, which assumes that differences in HIV prevalence among populations are adequately explained by variation in rates of unsafe sexual behaviors. But differences in sexual behavior cannot explain 250-fold differences in HIV prevalence among countries and increasing divergence in incidence. Such disparities point to biological characteristics of the pathogen, the host, and the environment, all of which influence individual risk of infection and the spread of infectious diseases in populations. This paper explores the ways in which Western constructions of race and sexuality have drawn attention to sexual behavior alone and away from scientific evidence of biological risk factors that increase HIV transmission in poor populations. Much of the discussion addresses sub-Saharan Africa, but the biological implications could apply to poor peopl...
The programmer as navigator

This year the whole world celebrates the five-hundredth birthday of Nicolaus Copernicus, the famous Polish astronomer and mathematician. In 1543, Copernicus published his book, Concerning the Revolutions of Celestial Spheres, which described a new theory about the relative physical movements of the earth, the planets, and the sun. It was in direct contradiction with the earth-centered theories which had been established by Ptolemy 1400 years earlier.
A new approach to unsupervised learning in deterministic environments

Abstract We present a new approach to the problem of inferring the structure of a deterministic finite-state environment by experimentation. The learner is presumed to have no a priori knowledge of the environment other than knowing how to perform a set of basic actions and knowing what elementary sensations are possible. The actions affect the state of the environment and the sensations of the learner according to deterministic rules that are to be learned. The goal of the learner is to construct a perfect model of his environment—one that enables him to predict perfectly the result of any proposed sequence of actions. Our approach is based on the notion of a “test”: a sequence of actions followed by a predicted sensation. The value (true or false) of a test at the current state can be easily determined by executing it. We define two tests to be “equivalent” if they have the same value at any global state. Our procedure uses systematic experimentation to discover the equivalence relation on tests determined by the environment, and produces a set of “canonical” tests. The equivalence classes produced correspond in many cases to a natural decomposition of the structure of the environment; one may say that our procedure discovers the appropriate set of “hidden state variables” useful for describing the environment. Our procedure has been implemented and appears to be remarkably effective in practice. For example, it has successfully inferred, in a few minutes each, the structure of Rubik's Cube (over 1019 global states) and a simple “grid world” environment (over 1011 global states); these examples are many orders of magnitude larger than what was possible with previous techniques.
Reduction Operations in Parallel Loops for GPGPUs

Manycore accelerators offer the potential of significantly improving the performance of scientific applications when offloading compute intensive portions of programs to the accelerators. Directive-based programming models such as OpenACC and OpenMP are high-level programming model for users to create applications for accelerators by annotating region of code for offloading with directives. In these programming models, most of the offloaded kernels are data parallel loops processing one or multiple multi-dimensional arrays, and it is often that scalar variables are used in the parallel loop body for reduction operations. Since reduction operation itself has loop-carried dependency preventing the parallelization of the loops, this could have a significant impact on the performance if not handled properly.In this paper, we present the design and parallelization of reduction operations in parallel loops for GPGPU accelerators. Using OpenACC as the high-level directive-based programing model, we discuss how reduction operations are parallelized when appearing in each level of the loop nest and thread hierarchy. We present how we handle the mapping of the loops and parallelized reduction to single- or multiple-level parallelism of GPGPU architectures. These algorithms have been implemented in the open source OpenACC compiler OpenUH. We compare our implementation with two other commercial OpenACC compilers using test cases and applications, and demonstrate better robustness and competitive performance than others.
A really temporal logic

We introduce a temporal logic for the specification of real-time systems. Our logic, TPTL, employs a novel quantifier construct for referencing time: the freeze quantifier binds a variable to the time of the local temporal context.TPTL is both a natural language for specification and a suitable formalism for verification. We present a tableau-based decision procedure and a model-checking algorithm for TPTL. Several generalizations of TPTL are shown to be highly undecidable.
Theoretical studies on the effects of blowing and suction in laminarseparated regions.

Consideration is given to two-dimensional, adiabatic laminar separated regions in supersonic flow that may be caused by forward-facing steps or control jets exhausting from the side of a flight vehicle. An order-of-magnitude analysis is presented to indicate that blowing or suction at the wall in the separated region may be a highly effective method for altering the force and moment characteristics of the separated pressure field acting upon the wall. By comparison with some forward-facing step experiments, it is shown that the two-moment, single-parameter viscous interaction method of Lees and Reeves yields a satisfactory correlation of step height with the theoretical height of the recirculation region of the separated flow. Therefore, the step height may be adequately computed without consideration of the reattachment process. This correlation is assumed valid when blowing or suction is included. The two-moment method is extended to include these mass change effects through use of a two-parameter method. The order-of-magnitude analysis is confirmed by detailed calculations for two cases, and theoretical effects of mass change on the induced pressure field are explored.
Losers Win, Winners Lose: Evidence against Market Efficiency

The goal of this research project was to evaluate whether there is statistically significant evidence of the Winner / Loser Phenomenon identified in DeBondt and Thaler (1985) using a unique data set and multiple examination windows. This study finds statistically significant evidence of short-run negative autocorrelation of returns. More importantly, if investors used a daily rebalance over this time period and invested simultaneously in the previous day’s loser ETF and the previous day’s winner ETF they would have obtained Cumulative Abnormal Returns of 113.50% and -134.13%, respectively. In addition, this study supports the experimental research findings documented in Bloomfield, R., Libby, R., and Nelson, M. (1998) and Bloomfield, R. and Hales, J. (2002) by providing evidence that (a) the performance of the market portfolio and the loser portfolio show signs of trending behavior and (b) the loser portfolio shows signs of significant outperformance conditioned upon a negative performance event.
Non-reciprocating Sharing Methods in Cooperative Q-Learning Environments

Past research on multi-agent simulation with cooperative reinforcement learning (RL) focuses on developing sharing strategies that are adopted and used by all agents in the environment. In this paper, we target situations where this assumption of a single sharing strategy that is employed by all agents is not valid. We seek to address how agents with no predetermined sharing partners can exploit groups of cooperatively learning agents to improve learning performance when compared to Independent learning. Specifically, we propose 3 intra-agent methods that do not assume a reciprocating sharing relationship and leverage the pre-existing agent interface associated with Q-Learning to expedite learning.
Flight Dynamics of High Aspect-Ratio Flying Wings: Effect of Large Trim Deformation

Analysis of flight dynamics of conventional airplane configurations usually begins with a rigid body approximation of the undeformed airplane structure. However, for high aspectratio flying wing configurations, static aeroelastic eects generate significant structural deformation and thus the aircraft configuration in flight is significantly dierent from the initial undeformed shape. As a consequence, flight dynamic studies conducted on a rigid body model based on the initial undeformed structure do not give an accurate assessment of the behavior of the airplane in flight. To overcome this, the deformed shape generated when the flying wing is subjected to static aeroelastic forces at trim, is used to define the rigid body configuration used for flight dynamic analysis. This paper studies the flight dynamic characteristics of the new rigid body configuration in relation to those of the rigid undeformed flying wing, and in relation to the stability characteristics of the complete aeroelastic model. The flight dynamic roots and the stability boundaries of the statically deformed rigid body configuration and the complete aeroelastic model are compared. It is found that staic aeroelatic deformation has a significant influence on the flight dynamic characteristics of high aspect-ratio HALE configurations.
Exploring adiabatic quantum trajectories via optimal control

Adiabatic quantum computation employs a slow change of a time-dependent control function (or functions) to interpolate between an initial and final Hamiltonian, which helps to keep the system in the instantaneous ground state. When the evolution time is finite, the degree of adiabaticity (quantified in this work as the average ground-state population during evolution) depends on the particulars of a dynamic trajectory associated with a given set of control functions. We use quantum optimal control theory with a composite objective functional to numerically search for controls that achieve the target final state with a high fidelity while simultaneously maximizing the degree of adiabaticity. Exploring the properties of optimal adiabatic trajectories in model systems elucidates the dynamic mechanisms that suppress unwanted excitations from the ground state. Specifically, we discover that the use of multiple control functions makes it possible to access a rich set of dynamic trajectories, some of which attain a significantly improved performance (in terms of both fidelity and adiabaticity) through the increase of the energy gap during most of the evolution time.
On low degree k-ordered graphs

A simple graph G is k-ordered (respectively, k-ordered hamiltonian) if, for any sequence of k distinct vertices v"1,...,v"k of G, there exists a cycle (respectively, a hamiltonian cycle) in G containing these k vertices in the specified order. In 1997 Ng and Schultz introduced these concepts of cycle orderability, and motivated by the fact that k-orderedness of a graph implies (k-1)-connectivity, they posed the question of the existence of low degree k-ordered hamiltonian graphs. We construct an infinite family of graphs, which we call bracelet graphs, that are (k-1)-regular and are k-ordered hamiltonian for odd k. This result provides the best possible answer to the question of the existence of low degree k-ordered hamiltonian graphs for odd k. We further show that for even k, there exist no k-ordered bracelet graphs with minimum degree k-1 and maximum degree less than k+2, and we exhibit an infinite family of bracelet graphs with minimum degree k-1 and maximum degree k+2 that are k-ordered for even k. A concept related to k-orderedness, namely that of k-edge-orderedness, is likewise strongly related to connectivity properties. We study this relation and give bounds on the connectivity necessary to imply k-(edge-)orderedness properties.
The persistence of job security in reforming socialist economies

The quest for efficiency underlies the reform efforts of the socialist economies, but job security and overemployment (redundant jobs) still characterize these economies. The author argues that reforming socialist economies have maintained job security not through planning but mainly through a complicated bargaining among coalitions that results in a massive redistribution. This redistribution amounts to a bailing out of the ailing or less productive firms and workers at the expense of the more productive firms and workers and of the household sector as a whole. The author substantiates his argument with an empirical analysis of the redistribution associated with the soft budget constraint in Yugoslavia in the 1970s and 1980s. He shows that redistribution is the outcome of a confrontation among coalitions and explains its compensatory nature.
Tropical Linear Spaces

We define the tropical analogues of the notions of linear spaces and Plucker coordinates and study their combinatorics. We introduce tropical analogues of intersection and dualization and define a tropical linear space built by repeated dualization and transverse intersection to be constructible. Our main result is that all constructible tropical linear spaces have the same $f$-vector and are “series-parallel”. We conjecture that this $f$-vector is maximal for all tropical linear spaces, with equality precisely for the series-parallel tropical linear spaces. We present many partial results towards this conjecture.
Erosion Pattern of Twisted Blades by Particle Laden Flows

Resultats d'une etude destinee a la prevision de l'erosion des aubes de turbomachine par un ecoulement charge de particules. Utilisation de methodes statistiques et combinaison des calculs de trajectoire des particules avec des donnees experimentales sur l'erosion afin de determiner l'erosion des aubes. Resultats montrant que la distribution de l'enlevement de matiere par erosion est fortement influencee par les dimensions des particules
Synthesis and thermal characteristics of dichlorobis(hydrazine)cadmium(II)

Abstract The preparation of Cd(N2H4)2Cl2 has been carried out using both ammonical and non-ammonical solutions of CdCl2. Decomposition reactions of the Cd(N2H4)2Cl2 are identical regardless of the method of preparation. The two decomposition steps involve the loss of 1.33 and 0.67 moles of N2H4 per mole of complex. However, the kinetic parameters for the reactions appear to be different depending on the method of preparation of the Cd(N2H4)2Cl2.