cssi/SciSciGPT-SciSciNet huggingface dataset:
Adaptive Synchronization of Semantically Compressed Instructional Videos for Collaborative Distance Learning

The increasing popularity of online courses has highlighted the need for collaborative learning tools for student groups. In addition, the introduction of lecture videos into the online curriculum has drawn attention to the disparity in the network resources available to students. We present an e-Learning architecture and adaptation model called AITV (Adaptive Interactive Internet Team Video), which allows groups of students to collaboratively view a video in synchrony. AITV upholds the invariant that each student will view semantically equivalent content at all times. A semantic compression model is developed to provide instructional videos at different level-of-details to accommodate dynamic network conditions and users’ system requirements. We take advantage of the semantic compression algorithm’s ability to provide different layers of semantically equivalent video by adapting the client to play at the appropriate layer that provides the client with the richest possible viewing experience. Video player actions, like play, pause and stop, can be initiated by any group member and and the results of those actions are synchronized with all the other students. These features allow students to review a lecture video in tandem, facilitating the learning process. Experimental trials show that AITV successfully synchronizes instructional videos for distributed students while concurrently optimizing the video quality, even under conditions of fluctuating bandwidth, by adaptively adjusting the quality level for each student while still maintaining the invariant.
Glasses and ceramics from colloids

Abstract This paper concerns the technical difficulties associated with the fabrication of amorphous and crystalline bodies from colloidal suspensions. When particles are grown in solution, it can be difficult to achieve homogeneity and prevent agglomeration, and the rate of production of particles is slow. Particle growth in the vapor phase is efficient, but the accessible range of compositions is smaller, and the particle size distribution cannot be as closely controlled as in solution methods. Future developments are likely to remove these limitations, so that colloidal methods will be used for the production of oxides, halides, and chalcogenides with high purity. Both glasses and fine-grained ceramics will be prepared in this way. The colloidal approach complements the sol-gel method by offering similarly high purity and homogeneity in larger pieces, but with higher firing temperatures.
New school leavers in Singapore

This paper reports on the labour market results of a cohort of graduates from five Singapore schools representing most areas where important changes in the educational system are taking place. The graduates left school in 1966–67 and were interviewed in 1970. Many of the graduates in the cohort found jobs almost immediately upon leaving school, but some did experience a substantial period of unemployment and even more reported difficulty in finding their first job. Eventually all became employed and at the time of interview unemployment was negligible. The initial unemployment and the difficulty in finding work were not related as to whether the education was technical or academic in nature. Income/cost ratios were calculated and used to rank the schools to see how they compared as social investments. Post-secondary, non-university education ranked highest, followed by secondary education with the university in third place. Within post-secondary, pre-university was a slightly better investment than the polytechnic largely because of a difference in costs. Within secondary schools there was virtually no difference between the technical secondary school, the academic secondary school and the vocational institute.
Supersymmetry in the Boundary Tricritical Ising Field Theory

We argue that it is possible to maintain both supersymmetry and integrability in the boundary tricritical Ising field theory. Indeed, we find two sets of boundary conditions and corresponding boundary perturbations which are both supersymmetric and integrable. The first set corresponds to a "direct sum" of two nonsupersymmetric theories studied earlier by Chim. The second set corresponds to a one-parameter deformation of another theory studied by Chim. For both cases, the conserved supersymmetry charges are linear combinations of Q, $\bar{Q}$ and the spin-reversal operator Γ.
Finding a maximum matching in a sparse random graph in O(n) expected time

We present a linear expected time algorithm for finding maximum cardinality matchings in sparse random graphs. This is optimal and improves on previous results by a logarithmic factor.
Technology and petroleum exhaustion: Evidence from two mega-oilfields

Abstract In this paper, we use results from the Hotelling model of non-renewable resources to examine the mainstream view among economists that improvements in recovery technology can offset declines in petroleum reserves. We present empirical evidence from two well-documented mega-oilfields: the Forties in the North Sea and the Yates in West Texas. Patterns of depletion in these two fields suggest that technology temporarily increases the rates of production at the expense of more pronounced rates of depletion in later years—in line with Hotelling's predictions. Insofar as our results are generalizable, they call into question the view of most economists that technology can mitigate absolute resource scarcity. This raises concerns about the capacity of current mega-fields to meet future oil demand.
Improved simulation of nondeterministic Turing machines

The standard simulation of a nondeterministic Turing machine (NTM) by a deterministic one essentially searches a large bounded-degree graph whose size is exponential in the running time of the NTM. The graph is the natural one defined by the configurations of the NTM. All methods in the literature have required time linear in the size S of this graph. This paper presents a new simulation method that runs in time O@?(S). The search savings exploit the one-dimensional nature of Turing machine tapes. In addition, we remove most of the time dependence on nondeterministic choices of states and tape head movements.
Dollarization does promote trade

Abstract This study re-evaluates the treatment effect of dollarization on trade while explicitly controlling for self-selection of policy adoption. Employing a variety of propensity score matching methods, we show that dollarization not only increases bilateral US trade with dollarized countries, but promotes a dollarizer’s bilateral trade with other dollar-zone countries as well.
The rural physician associate program: new directions in education for competency.

The Rural Physician Associate Program (RPAP) has 34 years experience in training 1097 medical students as independent distance learners in a 36-week, community-based continuity primary care experience. This program has been successful in preparing competitive students who select primary care residencies and return to rural practice. The RPAP program has been based on traditional apprenticestyle clinical teaching with the support of computer-based resources to enhance distance learning. However while the clinical exposure and development of medical skills was strong, there were weaknesses in evidence-based medicine and managing healthcare, and inconsistencies in community or population health learning. New directions in the educational program for RPAP are described that have been or are being developed to address the competencies as outlined by the Accreditation Council on Graduate Medical Education. They include online and other resources, preceptor education and support, interactive journaling and cases, electronic portfolios, community projects, observed structured clinical exams and examinations. Ongoing challenges to competency-based education include developing meaningful measures and tools to assess competence for areas such as professionalism or systems-based practice; providing faculty development toward being able to practice, teach and evaluate students with an understanding of the competencies; and to build in ways of practicing, learning and improving care that involve effective teams of health-care professionals.
Light stop searches at the LHC in events with one hard photon or jet and missing energy

Low energy supersymmetric models provide a solution to the hierarchy problem and also have the necessary ingredients to solve two of the most outstanding issues in cosmology: the origin of the baryon asymmetry and the source of dark matter. In the MSSM, weak scale generation of the baryon asymmetry may be achieved in the presence of light stops, with masses lower than about 130 GeV. Moreover, the proper dark matter density may be obtained in the stop-neutralino co-annihilation region, where the stop-neutralino mass difference is smaller than a few tens of GeV. Searches for scalar top quarks (stops) in pair production processes at the Tevatron and at the Large Hadron Collider (LHC) become very challenging in this region of parameters. At the LHC, however, light stops proceeding from the decay of gluino pairs may be identified, provided the gluino mass is smaller than about 900 GeV. In this article we propose an alternative method for stop searches in the co-annihilation region, based on the search for these particles in events with missing energy plus one hard photon or jet. We show that this method is quite efficient and, when complemented with ongoing Tevatron searches, allows to probe stop masses up to about 160 GeV, fully probing the region of parameters consistent with electroweak baryogenesis in the MSSM.
Sessile serrated polyp prevalence determined by a colonoscopist with a high lesion detection rate and an experienced pathologist

Background The prevalence of sessile serrated adenomas and/or polyps (SSA/Ps) is uncertain. Objective To determine the prevalence of SSA/Ps and SSA/Ps with cytologic dysplasia (SSA/P-CD) by using a colonoscopist with a high lesion detection rate and an expert in serrated lesion pathology. Design Retrospective screening colonoscopy study. Setting Academic endoscopy unit. Patients A total of 1910 average risk, asymptomatic patients aged ≥50 years underwent screening colonoscopy between August 2005 and April 2012 by a single colonoscopist with a high lesion detection rate. Interventions Slides of all lesions in the serrated class proximal to the sigmoid colon and all rectal and sigmoid colon serrated lesions >5 mm in size were reviewed by an experienced GI pathologist. Main Outcome Measurements Prevalence of SSA/Ps, defined as the proportion of patients with ≥1 SSA/P. Results There were 1910 patients, of whom 389 had 656 lesions in the serrated class. Review by the experienced GI pathologist determined a prevalence of SSA/Ps without cytologic dysplasia of 7.4% and SSA/Ps-CD of 0.6% (total SSA/P prevalence 8.1%). SSA/Ps and SSA/Ps-CD comprised 5.6% and 0.3%, respectively, of all resected polyps. The mean size of SSA/Ps was 7.13 mm (standard deviation [SD] 4.66), and 51 of 77 (66.2%) polyps ≥10 mm in the serrated class were SSA/Ps. Limitations Retrospective design. Conclusion A colonoscopist with a high lesion detection rate and an experienced pathologist identified a high prevalence (8.1%) of SSA/Ps in a screening population. SSA/Ps are more common than previously believed.
Antitumor agents. Part 202: Novel 2′-amino chalcones: design, synthesis and biological evaluation ☆

New 4',5',2,3,4-substituted 2'-amino chalcones were synthesized and evaluated for cytotoxicity against a panel of human tumor cell lines. Several compounds displayed significant cytotoxicity. The most promising lead molecule (10) also had high activity toward multi-drug resistant KB-VIN, and ovarian 1A9 cell lines. 2'-Amino chalcones demonstrated significantly increased antitumor activity compared with the corresponding chalcones, while, the epoxide derivatives generally showed greatly reduced activity.
Sequential voting with abstention

Abstract Dekel and Piccione [2000. Sequential voting procedures in symmetric binary elections. J. Polit. Economy 108, 34–55] have proven that information cascades do not necessarily affect the properties of information aggregation in sequential elections: under standard conditions, any symmetric equilibrium of a simultaneous voting mechanism is also an equilibrium of the correspondent sequential mechanism. We show that when voters can abstain, these results are sensitive to the introduction of an arbitrarily small cost of voting: the set of equilibria in the two mechanisms are generally disjoint; and the informative properties of the equilibrium sets can be ranked. If an appropriate q -rule is chosen, when the cost of voting is small the unique symmetric equilibrium of the simultaneous voting mechanism dominates all equilibria of the sequential mechanism.
Heavy particle irradiation, neurochemistry and behavior: thresholds, dose–response curves and recovery of function

Exposure to heavy particles can affect the functioning of the central nervous system (CNS), particularly the dopaminergic system. In turn, the radiation-induced disruption of dopaminergic function affects a variety of behaviors that are dependent upon the integrity of this system, including motor behavior (upper body strength), amphetamine (dopamine)-mediated taste aversion learning, and operant conditioning (fixed-ratio bar pressing). Although the relationships between heavy particle irradiation and the effects of exposure depend, to some extent, upon the specific behavioral or neurochemical endpoint under consideration, a review of the available research leads to the hypothesis that the endpoints mediated by the CNS have certain characteristics in common. These include: (1) a threshold, below which there is no apparent effect; (2) the lack of a dose-response relationship, or an extremely steep dose-response curve, depending on the particular endpoint; and (3) the absence of recovery of function, such that the heavy particle-induced behavioral and neural changes are present when tested up to one year following exposure. The current report reviews the data relevant to the degree to which these characteristics are common to neurochemical and behavioral endpoints that are mediated by the effects of exposure to heavy particles on CNS activity. c2004 COSPAR. Published by Elsevier Ltd. All rights reserved.
MHD processes in the outer heliosphere

The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
Perceptions and Practices: A Survey of Professional Engineers and Architects

This descriptive cross-sectional research study examines perceptions of time spent by architects and professional engineers on reading, writing, and evaluating various information products, as well as their perspectives of specific quality characteristics and the relative significance in meeting work goals. Professional engineers and architects were surveyed at seminars held at eight locations in seven states. Descriptive statistics were then used to investigate perceptions and relationships. Findings indicate architects and professional engineers spend the most amount of time reading correspondence and the least amount of time reading management reports. Respondents considered correspondence to be the most important reading activity. Participants also spend the most amount of time writing correspondence, closely followed by nearly equal time spent writing and editing technical reports and proposals. Finally, participants rated organization, comprehensiveness, and accuracy as the most important aspects while indicating mechanical issues such as grammar and spelling as the least important aspects of technical documents.
The Permanent and Inductive Magnetic Moments of Ganymede

Data acquired by the Galileo magnetometer on five passes by Ganymede have been used to characterize Ganymede's internal magnetic moments. Three of the five passes were useful for determination of the internal moments through quadrupole order. Models representing the internal field as the sum of dipole and quadrupole terms or as the sum of a permanent dipole field upon which is superimposed an induced magnetic dipole driven by the time varying component of the externally imposed magnetic field of Jupiter's magnetosphere give equally satisfactory fits to the data. The permanent dipole moment has an equatorial field magnitude 719 nT and is tilted by 176 degrees from the spin axis with the pole in the southern hemisphere rotated by 24 degrees from the Jupiter-facing meridian plane towards the trailing hemisphere. The data are consistent with an inductive response of a good electrical conductor of radius approximately 1 Ganymede radius. Although the data do not enable us to establish the presence of an inductive response beyond doubt, we favor the inductive response model because it gives a good fit to the data using only 4 parameters to describe the internal sources of fields, whereas the equally good dipole plus quadrupole fit requires 8 parameters. An inductive response is consistent with a buried conducting shell, probably liquid water with dissolved electrolytes, somewhere in the first few hundred km below Ganymede's surface. The depth at which the ocean is buried beneath the surface is somewhat uncertain, but our favored model suggests a depth of order 150 kilometers. As both temperature and pressure increase with depth and the melting temperature of pure ice decreases to a minimum at approximately 170 kilometer depth, it seems possible that near this location, a layer of water would be sandwiched between layers of ice.
Naive programmer problems with specification of transfer-of-control

We have conducted a series of experiments concerning the programming performance of persons with no prior contact with computers other than the training received in the experimental sessions. Our objective in these experiments is to identify design principles for facilitating communication between the naive user, as a problem solver, and a computer system. We view programming as a problem-solving activity, an instance of what generally may be called "procedure specification." We believe it possible to design computers as optimal problem-solving tools only if the operating characteristics of the problem solvers are known and taken into account. Consequently, we are seeking to discover the problems and processes involved in human specification of procedures, using experimental laboratory methods.
Murine FLT3 ligand-derived dendritic cell-mediated early immune responses are critical to controlling cell-free human T cell leukemia virus type 1 infection

Human T cell leukemia virus type 1 (HTLV-1) is associated with two immunologically distinct diseases: HTLV-1-associated myelopathy/tropical spastic paraparesis and adult T cell leukemia. We observed previously that depletion of dendritic cells (DCs) in CD11c-diphtheria toxin receptor transgenic mice followed by infection with cell-free virus led to greater proviral and Tax mRNA loads and diminished cellular immune response compared with mice infected with cell-associated virus. To understand the significance of these in vivo results and explore the host-pathogen interaction between DCs and cell-free HTLV-1, we used FLT3 ligand-cultured mouse bone marrow-derived DCs (FL-DCs) and chimeric HTLV-1. Phenotypically, the FL-DCs upregulated expression of surface markers (CD80, CD86, and MHC class II) on infection; however, the level of MHC class I remained unchanged. We performed kinetic studies to understand viral entry, proviral integration, and expression of the viral protein Tax. Multiplex cytokine profiling revealed production of an array of proinflammatory cytokines and type 1 IFN (IFN-α) by FL-DCs treated with virus. Virus-matured FL-DCs stimulated proliferation of autologous CD3(+) T cells as shown by intracellular nuclear Ki67 staining and produced IFN-γ when cultured with infected FL-DCs. Gene expression studies using type 1 IFN-specific and DC-specific arrays revealed upregulation of IFN-stimulated genes, most cytokines, and transcription factors, but a distinct downregulation of many chemokines. Overall, these results highlight the critical early responses generated by FL-DCs on challenge with cell-free chimeric HTLV-1.
Time-dependent, Multifluid, Magnetohydrodynamic Shock Waves with Grain Dynamics. I. Formulation and Numerical Tests

This is the first in a series of papers on the effects of dust on the formation, propagation, and structure of nonlinear MHD waves and MHD shocks in weakly ionized plasmas. We model the plasma as a system of nine interacting fluids, consisting of the neutral gas, ions, electrons, and six types of grain fluids comprised of very small grains or polycyclic aromatic hydrocarbons and classical grains in different charge states. We formulate the governing equations for perpendicular shocks under approximations appropriate for dense molecular clouds, protostellar cores, and protoplanetary disks. We describe a code that obtains numerical solutions using a finite difference method, and we establish its accuracy by comparing numerical and exact solutions for special cases.
Far Noise Field of a Two-Dimensional Subsonic Jet

The acoustical radiation characteristics of a high aspect ratio, cold subsonic, model slot jet have been investigated experimentally. Acoustical measurements were made in both a free-field environment and a reverberation field environment. Mean velocity distribution of the slot jet was determined to provide information on the mixing characteristics of the flow. Free-field results obtained reflected a characteristic asymmetrical directivity pattern of the slot jet noise. The total radiated sound power yielded a typical U to the 7-th power dependence on mean jet velocity. The experimental findings are compared with data from similar studies and also with radiation characteristics of circular cold subsonic jets.
Policy Effects in Hyperbolic vs. Exponential Models of Consumption and Retirement

This paper constructs a structural retirement model with hyperbolic preferences and uses it to estimate the effect of several potential Social Security policy changes. Estimated effects of policies are compared using two models, one with hyperbolic preferences and one with standard exponential preferences. Sophisticated hyperbolic discounters may accumulate substantial amounts of wealth for retirement. We find it is frequently difficult to distinguish empirically between models with the two types of preferences on the basis of asset accumulation paths or consumption paths around the period of retirement. Simulations suggest that, despite the much higher initial time preference rate, individuals with hyperbolic preferences may actually value a real annuity more than individuals with exponential preferences who have accumulated roughly equal amounts of assets. This appears to be especially true for individuals with relatively high time preference rates or who have low assets for whatever reason. This affects the tradeoff between current benefits and future benefits on which many of the retirement incentives of the Social Security system rest. Simulations involving increasing the early entitlement age and increasing the delayed retirement credit do not show a great deal of difference whether exponential or hyperbolic preferences are used, but simulations for eliminating the earnings test show a non-trivially greater effect when exponential preferences are used.
Stereospecific carbon-carbon bond formation at secondary carbons in cyclic sugars

Abstract An excellent leaving-group, triflate, at C-4 of the benzylated hexopyranose glycosides 1 and 2 was used to study the introduction of carbon branches in sugars. By using a phase-transfer reagent, a one-carbon source, cyanide ion, was used to prepare the displacement products 3 and 4 . Direct displacement by a malonate ester ion was also successful and gave rise to the corresponding products 5 and 6 . A significant difference in the chemistry of 5 and 6 was noted in that the galacto isomer 5 , under neutral conditions, rearranged to its 1,6-anhydride 7 with loss of the O-6 benzyl group; a rationalization for the difference in stability of 5 and 6 is presented.
An Efficient and Scalable Synthesis of Arabinosylguanine and 2′-Deoxy-2′-Fluoro-guanosine

Abstract An efficient conversion from commercially available 2, 6-diaminopurine-2′, 3′, 5′-tri-O-benzyl arabinoside to arabinosylguanine and its further transformation to 2′-deoxy-2′-fluoro-guanosine is outlined. This process has been used to produce more than one hundred grams of final product.
Diffusion theory of spin injection through resistive contacts

Insertion of a resistive contact between a ferromagnetic metal and a semiconductor microstructure is of critical importance for achieving efficient spin injection into a semiconductor. However, the equations of the diffusion theory are rather cumbersome for the junctions including such contacts. A technique based on deriving a system of self-consistent equations for the coefficients of spin injection, γ, through different contacts are developed. These equations are concise when written in the proper notations. Moreover, the resistance of a two-contact junction can be expressed in terms of γ's of both contacts. This equation makes calculating the spin valve effect straightforward, allows to find an explicit expression for the junction resistance and to prove that its nonequilibrium part is positive. Relation of these parameters to different phenomena like spin-e.m.f. and the contact transients is established. Comparative effect of the Coulomb screening on different parameters is clarified. It is also shown that the spin non-conservation in a contact can have a dramatic effect on the non-equilibrium resistance of the junction.
Structure of an adaptive grid computational method from the viewpoint of dynamic chaos

Abstract An attempt has been made to study the structure of an adaptive grid computational method for fluid dynamics based on the viewpoint of dynamical chaos. A simple one-dimensional convection-diffusion equation is used as the model problem. The emphasis here is not on the completeness of the results in all the parameter space, but the usefulness of the techniques utilized to study chaos for the area of computational fluid dynamics. It is demonstrated that a rich variety of patterns of the structure of the adaptive grid method can be observed, depending on the values of the preassigned parameters and Reynolds number. Both the equilibrium state and persistently chaotic state of the grid distribution can be obtained. With the same set of parameters, the basic structure of the adaptive grid method remains unchanged for a wide span of Reynolds number, but the randomness appears to increase with the Reynolds number. Besides, the intermittency scenario has also been observed. The findings from the study of the present simple model problem suggest the possibility of shedding new insights into computational fluid dynamics.
New Perspectives for QCD Physics at the LHC

I review a number of topics where conventional wisdom relevant to hadron physics at the LHC has been challenged. For example, the initial‐state and final‐state interactions of the quarks and gluons entering perturbative QCD hard‐scattering subprocesses lead to the breakdown of traditional concepts of factorization and universality for transverse‐momentum‐dependent observables at leading twist. The soft‐gluon rescattering effects, which are associated with the Wilson line of the propagating partons, also lead to Bjorken‐scaling single‐spin asymmetries, diffractive deep inelastic scattering, the breakdown of the Lam‐Tung leading‐twist relation in Drell‐Yan reactions, as well as nuclear shadowing. The Gribov‐Glauber theory applied to the antishadowing domain predicts that nuclear structure functions depend on the flavor quantum numbers of each quark and antiquark, thus explaining the anomalous nuclear dependence recently observed in deep‐inelastic neutrino scattering. Surprisingly, isolated hadrons can be pr...
Sensitivity limits of an infrared heterodyne spectrometer for astrophysical applications.

A discussion and an evaluation of the degradation in sensitivity is given for a heterodyne spectrometer employing a HgCdTe photodiode mixer and tunable diode lasers. The minimum detectable source brightness is considered as a function of the mixer parameters, transmission coefficient of the beam splitter, and local oscillator emission powers. The degradation in the minimum detectable line source brightness which results from the bandwidth being a function of the line width is evaluated and plotted as a function of the wavelength and bandwidth for various temperature to mass ratios. It is shown that the minimum achievable degradation in the sensitivity of a practical astronomical heterodyne spectrometer is approximately 30. Estimates of signal-to-noise ratios with which infrared line emission from astronomical sources of interest may be detected are given.
Walking accessibility to bus rapid transit: Does it affect property values? The case of Bogotá, Colombia

This research sheds light on the relation of bus rapid transit and residential property values within walking distance to the system. The case study was Bogota's Transmilenio (Colombia). This research conducted a city-wide econometric hedonic analysis with 2000 to 2004 Department of Housing Control data across different walking distances, subsystems (trunk, feeder), socio-economic strata and time. The main results showed that, with respect to the value of properties in relation to proximity, the housing market places value premiums on the properties in the immediate walking proximity of feeder lines. The analysis by socio-economic strata showed that middle-income properties were valued more if they fell closer to the system, while there were opposite results for low-income housing. Finally, analysis across time reflects slight average annual increases in property values correlated with the implementation of the system in two specific areas analyzed. Throughout the paper, the author acknowledges some of the challenges of using hedonic modeling for property value impact assessments and emphasizes that the interpretation of the results are case specific.
Global demons in field theory. Critical slowing down in the XY model

Abstract We investigate the use of global demons, a “canonical dynamics”, as an approach to simulating lattice regularized field theories. This deterministically chaotic dynamics is non-local and non-hamiltonian, and preserves the canonical measure rather than δ(H − E). We apply this inexact dynamics to the 2D XY model, comparing to various implementations of hybrid Monte Carlo, focusing on critical exponents and critical slowing down. In addition, we discuss a scheme for making energy non-conserving dynamical algorithms exact without the use of a Metropolis hit.
Spectrum of the complex Laplacian on product domains

We show that the spectrum of the complex Laplacian □ on a product of Hermitian manifolds is the Minkowski sum of the spectra of the complex Laplacians on the factors. We use this to show that the range of the Cauchy-Riemann operator ∂ is closed on a product manifold, provided it is closed on each factor manifold.
Nonextremal black hole microstates and U duality

A six-parameter family of five-dimensional black hole solutions is constructed which are labeled by their mass, two asymptotic scalar fields and three charges. It is shown that the Bekenstein-Hawking entropy is exactly matched, arbitrarily far from extremality, by a simple but mysterious duality-invariant extension of previously derived formulae for the number of D-brane states in string theory.
Innovations in the operation of future computers

Not many years ago the standard way of operating computers was in a single stream batch mode. The operator completely controlled the computer resource, setting up each job before its initiation, mounting the appropriate tapes and I/O media, initializing the machine, putting the appropriate program deck in the cardreader and so forth. The user interacted with the operator most often in a "closed shop" mode, giving the operator a run request from a card deck and tapes as needed, and leaving it to him to take care of applying the resources to the job.
Scalar waves on a naked-singularity background

We obtain global spacetime weighted-L2 (Morawetz) and L4 (Strichartz) estimates for a massless chargeless spherically symmetric scalar field propagating on a super-extremal (overcharged) Reissner–Nordstrom background. To do this we first discuss the well-posedness of the Cauchy problem for scalar fields on non-globally hyperbolic manifolds, review the role played by the Friedrichs extension and go over the construction of the function spaces involved. We then show how to transform this problem to one about the wave equation on the Minkowski space with a singular potential, and prove that the potential thus obtained satisfies the various conditions needed in order for the estimates to hold.
MORPHOLOGIES IN A CLUSTER OF EXTREMELY RED GALAXIES WITH OLD STELLAR POPULATIONS AT z = 1.34

We have identified a clustering of red galaxies from deep optical/IR images obtained as part of the Institute for Astronomy Deep Survey. Photometric spectral energy distributions indicate that most of these galaxies comprise nearly pure old stellar populations at a redshift near 1.4, and Keck spectroscopy of the three brightest red galaxies confirms this interpretation and gives redshifts ranging from 1.335 to 1.338. Four of the galaxies are close together on the sky and less than 30'' from an R = 13.5 star; we have obtained deep adaptive optics imaging of this group. Detailed analysis and modeling of the surface brightness profiles of these galaxies shows that two are normal elliptical galaxies, one is an S0, and one appears to be an essentially pure disk of old stars, with no significant bulge. All four are highly relaxed, symmetric systems. While the old, bulgeless disk galaxy represents a type that is rare at the present epoch, the other three galaxies have structural parameters that are essentially indistinguishable from those of present-day galaxies and differ only in the age of their stellar populations.
Handling qualities related to stall/spin accidents of supersonic fighter aircraft

This paper reviews the handling qualities which influence the high angle of attack (AOA) behavior of supersonic fighter aircraft in order to obtain a clearer understanding of the causes of stall/spin accidents. The results show that, because modern fighters suffer more serious consequences when control is lost, good handling qualities are essential for safe operation at high AOA. Relaxed static stability used on some fighter aircraft can result in control problems at high AOA owing to inertia coupling and the difficulty of a recovery from a deep stall. Indications are that the use of departure/spin resistance and an automatic spin prevention system will greatly improve the safety record for modern supersonic fighters.
Flow Oscillations of Spike-Tipped Bodies

The oscillating flow field around a spike-tipped body has been simulated by the numerical solution of the 3-D compressible Navier-Stokes equations at a Mach number of 3.0 and a nominal Reynolds number of 7.87 x 10 to the 6th/m. Computations were performed using a vectorized 3-D Navier-Stokes program on the STAR 100 computer. Numerical solutions confirmed the experimental result that the self-sustained oscillation occurs within a limited range of the protruded spike length to shoulder height ratio. The numerical result predicted correctly the discrete frequency range as well as the rms pressure intensity. The detailed flow structure is also presented and discussed.
Palladium-Catalyzed Cross-Coupling of N-Sulfonylaziridines with Boronic Acids

A mild palladium-catalyzed cross-coupling of unsubstituted and 2-alkyl-substituted aziridines with arylboronic acid nucleophiles is presented. The reaction is highly regioselective and compatible with diverse functionality. A catalytic amount of base, a sterically demanding triarylphosphine ligand, and a phenol additive are critical to the success of the reaction. Coupling of a deuterium-labeled substrate established that ring opening of the aziridine occurs with inversion of stereochemistry.
Dark matter in the left-right twin Higgs model

In the left-right twin Higgs model, one of the neutral Higgses is a natural candidate for WIMP dark matter. We analyzed the dark matter relic density in this framework and identified regions of parameter space that provide the right amount of dark matter. We also studied the dark matter in the more general inert Higgs doublet model in which the mass splittings between the dark matter and other particles do not follow the relations in the left-right twin Higgs model.
SLOAN LOW-MASS WIDE PAIRS OF KINEMATICALLY EQUIVALENT STARS (SLoWPoKES): A CATALOG OF VERY WIDE, LOW-MASS PAIRS

We present the Sloan Low-mass Wide Pairs of Kinematically Equivalent Stars (SLoWPoKES), a catalog of 1342 very-wide (projected separation 500?AU), low-mass (at least one mid-K to mid-M dwarf component) common proper motion pairs identified from astrometry, photometry, and proper motions in the Sloan Digital Sky Survey. A Monte Carlo-based Galactic model is constructed to assess the probability of chance alignment for each pair; only pairs with a probability of chance alignment ?0.05 are included in the catalog. The overall fidelity of the catalog is expected to be 98.35%. The selection algorithm is purposely exclusive to ensure that the resulting catalog is efficient for follow-up studies of low-mass pairs. The SLoWPoKES catalog is the largest sample of wide, low-mass pairs to date and is intended as an ongoing community resource for detailed study of bona fide systems. Here, we summarize the general characteristics of the SLoWPoKES sample and present preliminary results describing the properties of wide, low-mass pairs. While the majority of the identified pairs are disk dwarfs, there are 70 halo subdwarf (SD) pairs and 21 white dwarf-disk dwarf pairs, as well as four triples. Most SLoWPoKES pairs violate the previously defined empirical limits for maximum angular separation or binding energies. However, they are well within the theoretical limits and should prove very useful in putting firm constraints on the maximum size of binary systems and on different formation scenarios. We find a lower limit to the wide binary frequency (WBF) for the mid-K to mid-M spectral types that constitute our sample to be 1.1%. This frequency decreases as a function of Galactic height, indicating a time evolution of the WBF. In addition, the semi-major axes of the SLoWPoKES systems exhibit a distinctly bimodal distribution, with a break at separations around 0.1?pc that is also manifested in the system binding energy. Compared with theoretical predictions for the disruption of binary systems with time, we conclude that the SLoWPoKES sample comprises two populations of wide binaries: an old population of tightly bound systems, and a young population of weakly bound systems that will not survive more than a few Gyr. The SLoWPoKES catalog and future ancillary data are publicly available on the Internet for utilization by the astronomy community.
FLUID: Improving Throughputs in Enterprise Wireless LANs through Flexible Channelization

This paper introduces models and a system for designing 802.11 wireless LANs (WLANs) using flexible channelization&#x2014; the choice of an appropriate channel width and center frequency for each transmission. In contrast to current 802.11 systems that use fixed width channels, the proposed system, FLUID, configures all access points and their clients using flexible channels. We show that a key challenge in designing such a system stems from managing the effects of interference due to multiple transmitters employing variable channel widths, in a network-wide setting. We implemented FLUID in an enterprise-like setup using a 50 node testbed (with off-the shelf wireless cards) and we show that FLUID improves the average throughput by 59 percent across all PHY rates, compared to existing fixed-width approaches.
Discrete time from quantum physics

Abstract 't Hooft has recently developed a discretization of (2+1) gravity which has a multiple-valued Hamiltonian and which therefore admits quantum time evolution only in discrete steps. In this paper, we describe several models in the continuum with single-valued equations of motion in classical physics, but with multiple-valued Hamiltonians. Their time displacements in quantum theory are therefore obliged to be discrete. Classical models on smooth spatial manifolds are also constructed with the property that spatial displacements can be implemented only in discrete steps in quantum theory. All these models show that quantization can profoundly affect classical topology.
Lenses of Extremely Wide Angle for Airplane Mapping

If the illumination of the image produced by a wide-angle lens covering a field of 120° follows the cosine-fourth-power law, the illumination at the edge of the field will be one-sixteenth that at the center in the absence of vignetting. By introducing negative distortion, the illumination may be expected to be more uniform from the center to the edge of the field. In particular if there is no vignetting and if the diaphragm precedes the lens, there will be uniform illumination, even for a field as great as 180°, if the distortion is such that r′=f sinβ where r′ is the distance from center of the field to a given image point, β is the corresponding angular distance from the axis in the object space, and f is the focal length corresponding to the part of the image in the neighborhood of the axis.During the war Zeiss developed a mapping lens with a large amount of negative distortion and a second rectifying system by which undistorted copies could be obtained from the distorted negative made with the camera lens. A German mapping lens and rectifying unit have been brought to this country, and detailed results of tests made at the National Bureau of Standards are given in the following paper. The lens, termed the Pleon, covers a field of 130°, and the distortion closely follows the law r′=fβ, the distortion being somewhat less than that of the preceding formula. Measurements of the resolving power, of the effective size of the entrance pupil for different angular distances from the axis, and of the net distortion of the two systems are given. In the final print there is significant residual distortion resulting from the failure of the distortions of the two systems to exactly annul each other.
Regularized block Toeplitz covariance matrix estimation via Kronecker product expansions

In this work we consider the estimation of spatio-temporal covariance matrices in the low sample non-Gaussian regime. We impose covariance structure in the form of a sum of Kronecker products decomposition (Tsiligkaridis et al. 2013, Greenewald et al. 2013) with diagonal correction (Greenewald et al.), which we refer to as DC-KronPCA, in the estimation of multiframe covariance matrices. This paper extends the approaches of (Tsiligkaridis et al.) in two directions. First, we modify the diagonally corrected method of (Greenewald et al.) to include a block Toeplitz constraint imposing temporal stationarity structure. Second, we improve the conditioning of the estimate in the very low sample regime by using Ledoit-Wolf type shrinkage regularization similar to (Chen, Hero et al. 2010). For improved robustness to heavy tailed distributions, we modify the KronPCA to incorporate robust shrinkage estimation (Chen, Hero et al. 2011). Results of numerical simulations establish benefits in terms of estimation MSE when compared to previous methods. Finally, we apply our methods to a real-world network spatio-temporal anomaly detection problem and achieve superior results.
Fredholm determinants and the mKdV/sinh-Gordon hierarchies

For a particular class of integral operatorsK we show that the quantity $$\phi : = \log \det (I + K) - \log \det (I - K)$$ satisfies both the integrated mKdV hierarchy and the Sinh-Gordon hierarchy. This proves a conjecture of Zamolodchikov.
The 2MASS Color-Magnitude Diagram of the Center of the Sagittarius Dwarf Galaxy: Photometric Measurements of a Surprisingly High Mean Metallicity

We present the Two Micron All Sky Survey (2MASS) (J-K, K) color-magnitude diagram for the region within 1° of the center of the Sagittarius dwarf spheroidal galaxy. Using the slope of the red giant branch (RGB), we determine a mean metallicity for the main stellar population of [Fe/H] = -0.5 ± 0.2. The Sagittarius RGB possesses a blue tail that overlaps with the foreground Milky Way giant branch and suggests that approximately one-third of the RGB is more metal-poor than [Fe/H] ~ -1. Direct comparison with the Large Magellanic Cloud confirms the metal-rich nature of the bulk of the Sagittarius population. Our result is marginally consistent with the even higher metallicities determined from high-resolution spectroscopy.
Distributing content simplifies ISP traffic engineering

Several major Internet service providers today also offer content distribution services. The emergence of such "network-CDNs" (NCDNs) is driven both by market forces as well as the cost of carrying ever-increasing volumes of traffic across their backbones. An NCDN has the flexibility to determine both where content is placed and how traffic is routed within the network. However NCDNs today continue to treat traffic engineering independently from content placement and request redirection decisions. In this paper, we investigate the interplay between content distribution strategies and traffic engineering and ask whether or how an NCDN should address these concerns in a joint manner. Our experimental analysis, based on traces from a large content distribution network and real ISP topologies, shows that realistic (i.e., history-based) joint optimization strategies offer little benefit (and often significantly underperform) compared to simple and "unplanned" strategies for routing and placement such as InverseCap and LRU. We also find that the simpler strategies suffice to achieve network cost and user-perceived latencies close to those of a joint-optimal strategy with future knowledge.
P(i-PrNCH2CH2)3N: An efficient nonionic catalyst for the regioselective Michael addition of a β,γ-unsaturated ester and a nitrile

Abstract Michael additions of a β,γ-unsaturated ester and a nitrile to a variety of α,β-unsaturated ketones can be effected with high regioselectivity and in good yields using P(i-PrNCH2CH2)3N as a catalyst.
Analyzing emergent issues in women's health: the case of the toxic-shock syndrome.

Analyzing emergent issues in women's health, where the issue and its implications are still ambiguous but nevertheless have important consequences for women's health, poses particular problems for feminist researchers. Using the toxic‐shock syndrome as an example of such an issue, this paper reviews aspects of such analysis involving method, frameworks, and sources of data.
Facile Formation of Dehydroalanine From S-Nitrosocysteines

A reductive elimination of S-nitrosocysteines using phosphine substrates has been developed. This reaction converts unstable S-nitrosocysteines to dehydroalanine derivatives under very mild conditions. It can potentially be applied for the detection of protein S-nitrosation.