cssi/SciSciGPT-SciSciNet huggingface dataset:
Resolving a paradox of anomalous scalings in the diffusion of granular materials

Granular materials do not perform Brownian motion, yet diffusion can be observed in such systems when agitation causes inelastic collisions between particles. It has been suggested that axial diffusion of granular matter in a rotating drum might be “anomalous” in the sense that the mean squared displacement of particles follows a power law in time with exponent less than unity. Further numerical and experimental studies have been unable to definitively confirm or disprove this observation. We show two possible resolutions to this apparent paradox without the need to appeal to anomalous diffusion. First, we consider the evolution of arbitrary (non-point-source) initial data towards the self-similar intermediate asymptotics of diffusion by deriving an analytical expression for the instantaneous collapse exponent of the macroscopic concentration profiles. Second, we account for the concentration-dependent diffusivity in bidisperse mixtures, and we give an asymptotic argument for the self-similar behavior of such a diffusion process, for which an exact self-similar analytical solution does not exist. The theoretical arguments are verified through numerical simulations of the governing partial differential equations, showing that concentration-dependent diffusivity leads to two intermediate asymptotic regimes: one with an anomalous scaling that matches the experimental observations for naturally polydisperse granular materials, and another with a “normal” diffusive scaling (consistent with a “normal” random walk) at even longer times.
A canonical expansion of the product of two Stanley symmetric functions

We study the problem of expanding the product of two Stanley symmetric functions F w ?F u into Stanley symmetric functions in some natural way. Our approach is to consider a Stanley symmetric function as a stabilized Schubert polynomial $F_{w}=\lim_{n\to\infty}\mathfrak{S}_{1^{n}\times w}$ , and study the behavior of the expansion of $\mathfrak {S}_{1^{n}\times w}\cdot \mathfrak {S}_{1^{n}\times u}$ into Schubert polynomials as n increases. We prove that this expansion stabilizes and thus we get a natural expansion for the product of two Stanley symmetric functions. In the case when one permutation is Grassmannian, we have a better understanding of this stability. We then study some other related stability properties, providing a second proof of the main result.
Thermophysical properties of Apollo 14 fines

The vacuum thermal conductivity of lunar fines sample 14163 was measured for the approximate temperature range 100 to 400 deg K. Several sample densities from 1100 to 1800 kg/cu m were used. The temperature dependence of the conductivity was found to be well represented by the relation k = A + BT cubed, which is predicted by elementary theory. The coefficients A and B were obtained by least squares analysis of the data. The thermal diffusivity was calculated for the various densities by using specific heat data from the literature along with the measured conductivities. The results are compared with those obtained for Apollo 11, Apollo 12, and terrestrial basalt samples.
Superconductivity: after the fad

The author discusses the impact that new high-temperature superconductors are likely to have on the electric utility industry. The author identifies some of the practical problems that will have to be overcome first. This paper also gives an overview of the various efforts under way to solve those problems.
Two derivations of the uniform rule and an application to bankruptcy

Abstract We consider the problem of allocating a single infinitely divisible commodity to agents with single-peaked preferences, and establish two properties of the rule that has played the central role in the analysis of this problem, the uniform rule. Among the efficient allocations, it selects (1) the one at which the difference between the largest amount received by any agent and the smallest such amount is minimal, and (2) the one at which the variance of the amounts received by all the agents is minimal. We also show that an important solution for bankruptcy problems, the constrained equal-award solution, can be characterized by analogous minimization exercises, subject to different constraints. © 1997 Elsevier Science S.A.
Matter couplings in partially broken extended supersymmetry

Abstract We use nonlinear realizations to describe the spontaneous breaking of N = 2 supersymmetry to N = 1 in four dimensions. We identify the Goldstone multiplet with an N = 1 chiral superfield, and show that chiral N = 1 matter is consistent with the partially broken N = 2 supersymmetry. We find that the chiral matter can be in any representation of the gauge group; no mirror particles are required. We present the Goldstone action and the general couplings to N = 1 matter to the first nontrivial order in the scale of symmetry breaking.
Determining finite volume elements for the 2D Navier-Stokes equations

We consider the 2D Navier-Stokes equations on a square with periodic boundary conditions. Dividing the square into N equal subsquares, we show that if the asymptotic behavior of the average of solutions on these subsquares (finite volume elements) is known, then the large time behavior of the solution itself is completely determined, provided N is large enough. We also establish a rigorous upper bound for N needed to determine the solutions to the Navier-Stokes equation in terms of the physical parameters of the problem.
On uniqueness of tensor products of irreducible categorifications

In this paper, we propose an axiomatic definition for a tensor product categorification. A tensor product categorification is an abelian category with a categorical action of a Kac–Moody algebra $${\mathfrak {g}}$$ in the sense of Rouquier or Khovanov–Lauda whose Grothendieck group is isomorphic to a tensor product of simple modules. However, we require a much stronger structure than a mere isomorphism of representations; most importantly, each such categorical representation must have a standardly stratified structure compatible with the categorification functors, and with combinatorics matching those of the tensor product. With these stronger conditions, we recover a uniqueness theorem similar in flavor to that of Rouquier for categorifications of simple modules. Furthermore, we already know of an example of such a categorification: the representation category of an algebra $$T^{\underline{\varvec{\lambda }}}$$ previously defined by the second author using generators and relations. Next, we show that tensor product categorifications give a categorical realization of tensor product crystals analogous to that for simple crystals given by cyclotomic quotients of KLR algebras. Examples of such categories are also readily found in more classical representation theory; for finite and affine type A, tensor product categorifications can be realized as quotients of the representation categories of cyclotomic $$q$$ -Schur algebras.
HOW GOOD A CLOCK IS ROTATION? THE STELLAR ROTATION-MASS-AGE RELATIONSHIP FOR OLD FIELD STARS

The rotation-mass-age relationship offers a promising avenue for measuring the ages of field stars, assuming the attendant uncertainties to this technique can be well characterized. We model stellar angular momentum evolution starting with a rotation distribution from open cluster M37. Our predicted rotation-mass-age relationship shows significant zero-point offsets compared to an alternative angular momentum loss law and published gyrochronology relations. Systematic errors at the 30% level are permitted by current data, highlighting the need for empirical guidance. We identify two fundamental sources of uncertainty that limit the precision of rotation-based ages and quantify their impact. Stars are born with a range of rotation rates, which leads to an age range at fixed rotation period. We find that the inherent ambiguity from the initial conditions is important for all young stars, and remains large for old stars below 0.6 M ☉. Latitudinal surface differential rotation also introduces a minimum uncertainty into rotation period measurements and, by extension, rotation-based ages. Both models and the data from binary star systems 61 Cyg and α Cen demonstrate that latitudinal differential rotation is the limiting factor for rotation-based age precision among old field stars, inducing uncertainties at the ~2 Gyr level. We also examine the relationship between variability amplitude, rotation period, and age. Existing ground-based surveys can detect field populations with ages as old as 1-2 Gyr, while space missions can detect stars as old as the Galactic disk. In comparison with other techniques for measuring the ages of lower main sequence stars, including geometric parallax and asteroseismology, rotation-based ages have the potential to be the most precise chronometer for 0.6-1.0 M ☉ stars.
Capturing the Essence of Organic Synthesis: From Bioactive Natural Products to Designed Molecules in Today's Medicine

In this Perspective, I outline my group’s research involving the chemical syntheses of medicinally important natural products, exploration of their bioactivity, and the development of new asymmetric carbon−carbon bond-forming reactions. This paper also highlights our approach to molecular design and synthesis of conceptually novel inhibitors against target proteins involved in the pathogenesis of human diseases, including AIDS and Alzheimer’s disease.
Determinating timing channels in compute clouds

Timing side-channels represent an insidious security challenge for cloud computing, because: (a) massive parallelism in the cloud makes timing channels pervasive and hard to control; (b) timing channels enable one customer to steal information from another without leaving a trail or raising alarms; (c) only the cloud provider can feasibly detect and report such attacks, but the provider's incentives are not to; and (d) resource partitioning schemes for timing channel control undermine statistical sharing efficiency, and, with it, the cloud computing business model. We propose a new approach to timing channel control, using provider-enforced deterministic execution instead of resource partitioning to eliminate timing channels within a shared cloud domain. Provider-enforced determinism prevents execution timing from affecting the results of a compute task, however large or parallel, ensuring that a task's outputs leak no timing information apart from explicit timing inputs and total compute duration. Experiments with a prototype OS for deterministic cloud computing suggest that such an approach may be practical and efficient. The OS supports deterministic versions of familiar APIs such as processes, threads, shared memory, and file systems, and runs coarse-grained parallel tasks as efficiently and scalably as current timing channel-ridden systems.
Equations of the (2,0) theory and knitted fivebranes

We study non-linear corrections to the low-energy description of the (2,0) theory. We argue for the existence of a topological correction term similar to the C3∧X8(R) in M-theory. This term can be traced to a classical effect in supergravity and to a one-loop diagram of the effective 4+1D Super Yang-Mills. We study other terms which are related to it by supersymmetry and discuss the requirements on the subleading correction terms from M(atrix) theory. We also speculate on a possible fundamental formulation of the theory.
Resolving the pulsations of subdwarf B stars: PG 0154+182, HS 1824+5745 and HS 2151+0857

We continue our programme of extended single-site observations of pulsating subdwarf B (sdB) stars and present the results of extensive time-series photometry to resolve the pulsation spectra for use in asteroseismological analyses. PG 0154+182, HS 1824+5745 and HS2151+0857 were observed at the MDM Observatory during 2004 and 2005. Our observations are sufficient to resolve the pulsations of all three target stars. We extend the number of known frequencies for PG 0154+182 from one to six, confirm that HS 1824+5745 is a monoperiodic pulsator and extend the number of known frequencies to five for HS 2151+0857. We perform standard tests to search for multiplet structure, measure amplitude variations as pertains to stochastic excitation and examine the mode density to constrain the mode degree l.
Consumers, experts, and online product evaluations: Evidence from the brewing industry

Abstract The growth of the Internet has led to a dramatic increase in the number of consumer or “user” product ratings, which are posted online by individuals who have consumed a good, and are available to other individuals as they make decisions about which products to purchase. These ratings have the potential to substantially improve the match between products and consumers, however the extent to which they do so likely depends on whether the ratings reflect actual consumer experiences. This paper evaluates one potential source of bias in consumer ratings: mimicry of the reviews of experts. Using a rich dataset on consumer product ratings from the brewing industry and a regression discontinuity empirical framework, I show that expert reviews influence consumer ratings. Consumer ratings fall in response to negative expert reviews and increase in response to positive expert reviews. The results are most pronounced for strongly negative or strongly positive expert reviews. This mimicry limits the extent to which information on product quality from actual consumer experiences diffuses to the population. I suggest that “nudges” could be implemented to limit the extent to which mimicry affects ratings.
Redefining the Relationship Between Sperm Deoxyribonucleic Acid Fragmentation as Measured by the Sperm Chromatin Structure Assay and Outcomes of Assisted Reproductive Techniques

Objective To test the hypothesis that couples with sperm chromatin structure assay (SCSA) DNA fragmentation index (DFI) values >27% would not achieve pregnancy with assisted reproductive techniques (ART) and to investigate how DFI and high DNA stainability (HDS), as measured by the SCSA, affect fertilization, cleavage, implantation, and pregnancy rates in IVF cycles. Design Prospective clinical study. Setting Academic human reproduction laboratory. Patient(s) One hundred couples undergoing IVF with conventional insemination or intracytoplasmic sperm injection. Intervention(s) Testing with SCSA was performed by SCSA Diagnostics (Brookings, South Dakota) on a semen aliquot taken from ejaculate used for ART. Main Outcome Measure(s) Relating total DFI and HDS to conventional semen parameters and cycle-specific outcomes after ART. Result(s) Nine of nineteen couples achieved clinical pregnancy when DFI was ≥27%, and 2 of 22 couples achieved clinical pregnancy when DFI was ≤9%. One of nine couples achieved clinical pregnancy with HDS >17%. The DFI was negatively correlated with sperm density ( r = −0.23, P r = −0.55, P r = −0.37, P Conclusion(s) Sperm chromatin structure assay failed to identify elevated DFI thresholds for negative pregnancy outcome after ART. Patients with low DFI (≤9%) were least likely to become pregnant, which is also contradictory to SCSA marketing, which states that DFIs of ≤15% have excellent fertility potential. Patients with HDS ≥17% had low pregnancy rates, indicating decreased fertility potential, which deserves further investigation. Larger studies are necessary to confirm that low DFI is associated with decreased fertility and, if proved, might redefine the use of the SCSA in evaluating infertility.
A faster strongly polynomial time algorithm for submodular function minimization

We consider the problem of minimizing a submodular function f defined on a set V with n elements. We give a combinatorial algorithm that runs in O(n 5EO + n 6) time, where EO is the time to evaluate f(S) for some $$S \subseteq V$$. This improves the previous best strongly polynomial running time by more than a factor of n. We also extend our result to ring families.
GROWTH KINETICS OF NANOCRYSTALLINE ZNO PARTICLES FROM COLLOIDAL SUSPENSIONS

Colloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. The particle aging kinetics were determined by monitoring the optical band edge absorption and using the effective mass model to approximate the particle size as a function of time. We show that the growth kinetics of the ZnO particles follow the Lifshitz−Slyozov−Wagner theory for Ostwald ripening. In this model, the higher curvature and hence chemical potential of smaller particles provides a driving force for dissolution. The larger particles continue to grow by diffusion-limited transport of species dissolved in solution.
Residents' perceptions of the impacts of special event tourism

Purpose – The purpose of this research was to explore residents' perceptions of special event tourism at a destination. Specifically, the research examined residents' perceptions of the social, economic and environmental impacts of special event tourism on the destination. The study also examined dimensions of community life that were impacted or curtailed as a result of event tourism.Design/methodology/approach – Data were collected by means of a telephone survey. The survey solicited residents' perceptions of the social, economic, and environmental impacts of special event tourism. The study was exploratory and followed a descriptive design.Findings – Residents are generally in favor of events that contribute socially and economically to the destination. They are, however, not ambivalent to some of the negative impacts, but are willing to cope with these negative impacts as long as the perceived benefits exceed the negative impacts.Research limitations/implications – Although the sample was adequate for...
Effective Police Homicide Investigations Evidence From Seven Cities With High Clearance Rates

At present, the average homicide clearance rate in the United States is approximately 65%, down roughly 15% from the mid-1970s. This research seeks to inform how police can best improve homicide clearance rates by identifying best practices in homicide investigations. To accomplish this goal, as part of a federally funded project, seven geographically representative law enforcement agencies were identified that had at least 24 homicides in 2011 and had a clearance rate of 80% or higher from which effective investigative practices could be gleaned. Qualitative findings indicate that a strong community policing presence, collaboration with external agencies, and an innovative culture facilitate high rates of homicide clearance. Implications for policy and future research are discussed.
Open and Rigid Communication Networks: A Reevaluation by Simulation

This study was designed in anticipation that the inconsistent findings throughout the Communication Networks literature could be resolved by including individual learning and reinforcement into the CNE paradigm during long periods of problem solving, The results indicated little differences in productivity between networks in the long run solution rates through time and rates of pattern formation throughout the time series. As the findings of this study suggest, problem solving is composed of transition states in learning, Therefore, rather than being concerned with tests of significance and using large samples for short time periods a more effective strategy would be to examine smaller samples for a rather extended time period.
Marine Insurance in Britain and America, 1720-1844: A Comparative Institutional Analysis

This article examines how the marine insurance industry evolved in Britain and America during its critical formative period, focusing on the information asymmetries and agency problems that were inherent to the technology of overseas trade at the time, and on the path-dependent manner in which the institutions that addressed these problems evolved. I argue that the market was characterized by multiple equilibria because of a potential lemons problem. Exogenous shocks and endogenous institutional development combined to bring about a bifurcation of institutional structure, the effects of which persist to the present day. M arine insurance played a vital role in facilitating the expansion of trade during the eighteenth and early nineteenth centuries, but the industry developed in different ways in different countries. By the midnineteenth century, the British marine insurance market was dominated by Lloyd's of London, a marketplace where private individuals risked their personal fortunes by insuring vessels and cargoes with unlimited liability. In contrast, in the United States, private underwriting had virtually disappeared, and marine insurance was predominantly carried out by joint-stock corporations. To account for the success of private underwriting in Britain and its demise in the United States, I focus on the information asymmetries and agency problems that were inherent to the technology of overseas trade at the time, how institutions arose to address these problems, and how exogenous and endogenous changes in the political, legal, and economic environment affected the evolution of these institutions over time. Broadly, the argument is as follows. In Britain, the Bubble Act of 1720 temporarily limited the development of marine insurance corporations, thereby enabling Lloyd's coffee house to develop as a center where individual private underwriting could flourish. Lloyd's became a
Carcinoma of the cervix: the effect of age on survival.

Abstract A significant decrease in 5-year survival was found in 265 patients with invasive cervical cancer under the age of 35 compared to 820 over the age of 35 in all stages except Stage I-A and Stage IV. The exact reasons for the differences remain obscure. The greatest number of failures occurred in Stage II-B patients where, despite central control of disease, distant metastases developed. This suggests that the pretreatment evaluation of younger patients, especially those with Stage II-B cancer, should be more aggressive at attempts to detect cancer beyond the usual treatment fields. The poorer prognosis for patients under age 35 could not be explained on the basis of cell type. It was found that patients with large-cell, keratinizing cancers had a somewhat improved survival over patients with large-cell, non-keratinizing cancers.
A Multiple Discrete-Continuous Nested Extreme Value (MDCNEV) Model: Formulation and Application to Non-worker Activity Time-Use and Timing Behavior on Weekdays

This paper develops a multiple discrete-continuous nested extreme value (MDCNEV) model that relaxes the independently distributed (or uncorrelated) error terms assumption of the multiple discrete-continuous extreme value (MDCEV) model proposed by Bhat [Bhat, C.R., 2005. A multiple discrete-continuous extreme value model: formulation and application to discretionary time-use decisions. Transportation Research Part B 39 (8), 679-707; Bhat, C.R., 2008. The multiple discrete-continuous extreme value (MDCEV) model: role of utility function parameters, identification considerations, and model extensions. Transportation Research Part B 42 (3), 274-303]. The MDCNEV model captures inter-alternative correlations among alternatives in mutually exclusive subsets (or nests) of the choice set, while maintaining the closed-form of probability expressions for any (and all) consumption pattern(s). The MDCNEV model is applied to analyze non-worker out-of-home discretionary activity time-use and activity timing decisions on weekdays using data from the 2000 San Francisco Bay Area data. This empirical application contributes to the literature on activity time-use and activity timing analysis by considering daily activity time-use behavior and activity timing preferences in a unified utility maximization-based framework. The model estimation results provide several insights into the determinants of non-workers' activity time-use and timing decisions. The MDCNEV model performs better than the MDCEV model in terms of goodness of fit. However, the nesting parameters are very close to 1, indicating low levels of correlation. Nonetheless, even with such low correlation levels, empirical policy simulations indicate non-negligible differences in policy predictions and substitution patterns exhibited by the two models. Experiments conducted using simulated data also corroborate this result.
Synthesis, structure, and bonding of open-shell Sr3In5: an unusual electron deficiency in an indium network, beyond the Zintl boundary.

The new title compound has been synthesized and characterized by physical property measurements and electronic structure calculations. The results ratify the highly uncommon deficiency of one electron that has been long speculated for its Ca3Ga5-type structure on the basis of the simple Zintl electron counting formalism. In the Sr3In5 structure (Cmcm), 4- and 2-bonded indium atoms in a 4:1 ratio form a three-dimensional classical network that encapsulates strontium atoms in its narrow channels. The electrical conductivity of the compound shows typical metallic behavior. The detailed electronic structure analysis suggests that the electron hole is mainly localized on a nonbonding p-orbital on the 2-bonded indium atoms, and that these orbitals, stacked in a σ-type way along a (4.97 A), interact only weakly with each other to form highly one-dimensional bands.
Evaluation of Task Assignment Policies for Supercomputing Servers: The Case for Load Unbalancing and Fairness

While the MPP is still the most common architecture in supercomputer centers today, a simpler and cheaper machine configuration is appearing at many supercomputing sites. This alternative setup may be described simply as a collection of multiprocessors or a distributed server system. This collection of multiprocessors is fed by a single common stream of jobs, where each job is dispatched to exactly one of the multiprocessor machines for processing. The biggest question which arises in such distributed server systems is what is a good rule for assigning jobs to host machines: i.e. what is a good task assignment policy. Many task assignment policies have been proposed, but not systematically evaluated under supercomputing workloads. In this paper we start by comparing existing task assignment policies using a trace-driven simulation under supercomputing workloads. We validate our experiments by providing analytical proofs of the performance of each of these policies. These proofs also help provide much intuition. We find that while the performance of supercomputing servers varies widely with the task assignment policy, none of the above task assignment policies perform as well as we would like. We observe that all policies proposed thus far aim to balance load among the hosts. We propose a policy which purposely unbalances load among the hosts, yet, counter-to-intuition, is also fair in that it achieves the same expected slowdown for all jobs – thus no jobs are biased against. We evaluate this policy again using both trace-driven simulation and analysis. We find that the performance of the load unbalancing policy is significantly better than the best of those policies which balance load.
Casimir-Polder long-range interaction potentials between alkali-metal atoms

A complete description of the multipolar Casimir-Polder effects between two alkali-metal atoms in the ground state is presented. We give both general and particular expressions for the electric-electric, electric-magnetic, magnetic-magnetic, diamagnetic-electric, and diamagnetic-magnetic two-photon multipole processes, many of which have not been discussed previously in literature, to our knowledge. The asymptotic behavior of the Casimir-Polder potential is studied in terms of the ${K}_{7}, {K}_{9},$ and ${K}_{11}$ long-range coefficients. We have established the range of validity of the Casimir-Polder potential by analyzing the first-order correction to the energy given by the matrix element of the contact interaction term between the atomic charge distributions. Numerical values for the Casimir-Polder long-range interaction potentials for both homonuclear and heteronuclear alkali-metal dimers are presented. Comparisons with previous analytical and numerical results are included.
Surface reactivity and surface spectroscopies

Abstract The formation of gaseous reaction products which result directly from surface reactions can be followed using multiplexed quadrupole mass spectrometry in ultrahigh vacuum by temperature-programmed reaction spectroscopy. Other methods such as electron energy loss vibrational spectroscopy and near-edge X-ray absorption fine structure analysis provide important information about the identity and structure of the intermediates. In this paper the combined use of these methods for understanding the oxidation of acetonitrile and formic acid on Ag(110) is described. For the -CH 2 CN intermediate formed in acetonitrile oxidation, interesting local azimuthal ordering of the -CN group along the [001] direction is observed. In another example, the combination of these methods shows that near-edge analysis is capable of detecting the dynamical moation of the adsorbed formate species on Ag(110).
Palladium-Catalyzed α-Arylation of Zinc Enolates of Esters: Reaction Conditions and Substrate Scope

The intermolecular α-arylation of esters by palladium-catalyzed coupling of aryl bromides with zinc enolates of esters is reported. Reactions of three different types of zinc enolates have been developed. α-Arylation of esters occurs in high yields with isolated Reformatsky reagents, with Reformatsky reagents generated from α-bromo esters and activated zinc, and with zinc enolates generated by quenching alkali metal enolates of esters with zinc chloride. The use of zinc enolates, instead of alkali metal enolates, greatly expands the scope of the arylation of esters. The reactions occur at room temperature or at 70 °C with bromoarenes containing cyano, nitro, ester, keto, fluoro, enolizable hydrogen, hydroxyl, or amino functionality and with bromopyridines. The scope of esters encompasses acyclic acetates, propionates, and isobutyrates, α-alkoxyesters, and lactones. The arylation of zinc enolates of esters was conducted with catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) or the highly reactive dimeric Pd(I) complex {[P(t-Bu)3]PdBr}2.
Evaluating the "friendliness" of a timesharing system

The decade of the Sixties served to introduce most university campuses to the computer; the Seventies brought the computer, via a terminal, into every facet of university life. Computing in the Eighties will cause every university and college to evaluate and reconsider its exploitation of modern computing equipment for education and research.For example, at Northwestern University, it was recognized that continued growth in timesharing would be a major factor in computing at NU in the 1980s and that this growth would come from a large community of new users and of casual users. In January 1980, the Computing Center began a long-range planning study. A five-year equipment enhancement and replacement plan was to be developed which was intended to reverse an unsatisfactory trend toward computer saturation, to further improve and modernize our computer offerings, and to ensure that NU remained on a path of excellence in computing. Since time-sharing had already increased to over 50% of the total usage of the computer, a decision was made to begin the evaluation of modern timesharing systems, with special emphasis in two areas: 1) efficiency and reliability, and 2) the user interface.This paper describes the processes which were developed and used for the evaluation of the user interface, or as it came to be known, the "friendliness" study [1].
Effect of damage on the impact response of composite laminates

The effect that the presence of damage has on the impact response of composite laminates was studied. The impact response was segmented into two phenomena: "local" contact response and "global" structural response. These phenomena were characterized by conducting static indentation tests and impact tests, respectively. Tests were conducted on [+45/0]2~ graphitelepoxy laminates with and without predamage. The force versus indentation results were compared for the "local" response and the force and displacement versus time histories were compared for the "global" response. The static indentation results indicate that the presence of damage causes the response to change as it requires more force to cause the same amount of indentation when damage is present. This is attributed to the ability of the surface of the damaged laminate to better conform to the indentor. However, the global response was unaltered by the presence of damage as the force and displacement versus time histories were not affected. This is in part attributable to the fact that the size of the damage is an order of magnitude smaller than the length important in the structural response. However, the forces in these impact events were below those forces in the static indentation test where there was a significant difference in the behavior between the undamaged and predamaged cases. It is therefore likely that differences would be seen in the force versus time history for more severe impact events.
A Statistical Survey of Hard X-ray Spectral Characteristics of Solar Flares with Two Footpoints

Using RHESSI data, we have analyzed 172 hard X-ray (HXR) peaks during 53 solar flares that exhibited a double-footpoint structure. Fitting both footpoints with power laws, we find that spectral index differences Δγ range mostly between 0 to 0.6, and only rarely go beyond. Asymmetries between footpoints were not observed to be significantly dependent on their mean heliographic position, their relative position with respect to each other, nor their orientation with respect to the solar equator. By assuming a symmetric acceleration process, it is also clear that differences in footpoint spectral indices and footpoint flux ratios can seldom be attributed to a difference in column densities between the two legs of a coronal loop. Our results corroborate better the magnetic mirror trap scenario. Moreover, footpoint asymmetries are more marked during times of peak HXR flux than when averaging over the whole HXR burst, suggesting that the magnetic configuration evolves during individual HXR bursts. We also observed a linear correlation between the peak 50-keV flux and the peak GOES 1 – 8 A channel flux and that HXR burst duration seem correlated with loop length.
Semisimple Hopf actions on commutative domains

Abstract Let H be a semisimple (so, finite dimensional) Hopf algebra over an algebraically closed field k of characteristic zero and let A be a commutative domain over k. We show that if A arises as an H-module algebra via an inner faithful H-action, then H must be a group algebra. This answers a question of E. Kirkman and J. Kuzmanovich and partially answers a question of M. Cohen. The main results of this article extend to working over k of positive characteristic. On the other hand, we obtain results on Hopf actions on Weyl algebras as a consequence of the main theorem.
Synthesis and Size Control of Monodispersed Al-Sulfonated Polycarboxylic Acid Nanoparticles and Their Transport in Porous Media

Sulfonated polymers are used in the oil field for scale inhibition. In this study, Al-sulfonated polycarboxylic acid (Al-SPCA) hybrid nanoparticles (NPs) were prepared by taking an environmentally friendly approach. The particle size of these materials was controlled at approximately 80 nm by applying hydrothermal synthetic methods with urea as a slow-neutralization agent. Reaction parameters (e.g., concentration of salt solution, reaction time, urea concentration, and ionic strength) were investigated to optimize NP synthesis. The mobility of Al-SPCA hybrid NPs decreases dramatically in a 1% (wt/wt) KCl solution. With phosphinopolycarboxylic acid (PPCA) as a dispersant, NPs were well-suspended in a 1% KCl solution. Absorption of PPCA by hybrid NPs increases their negative surface charge and decreases particle deposition. The retention and flowback performance of hybrid NPs was compared with the neat-chemical-squeeze simulation in ground-core-column experiments. The results show that the slow release of sulfonated polymer from solid hybrid NPs in a porous medium may have potential inhibitor-treatment application in the oil field.
Generalized higher order spt-functions

We give a new generalization of the spt-function of G.E. Andrews, namely \(\operatorname {Spt}_{j}(n)\), and give its combinatorial interpretation in terms of successive lower-Durfee squares. We then generalize the higher order spt-function \(\operatorname {spt}_{k}(n)\), due to F.G. Garvan, to \({}_{j\!}\operatorname {spt}_{k}(n)\), thus providing a two-fold generalization of \(\operatorname {spt}(n)\), and give its combinatorial interpretation. Lastly, we show how the positivity of jsptk(n) can be used to generalize Garvan’s inequality between rank and crank moments to the moments of j-rank and (j+1)-rank.
Observed solar cycle modulation of galactic cosmic rays over a range of rigidities

Abstract We have studied the long-term, steady-state, solar cycle modulation of galactic cosmic ray intensity for seven cycles (17–23). Our analysis is based on the data obtained with a variety of detectors on earth (neutron monitors of the global network and muon detectors) as well as telescopes flown on high altitude balloons and on-board near-earth satellites. The median rigidity of response for these detectors to galactic cosmic ray spectrum lies in the range 1–70 GV. We correlate cosmic ray data to sunspot numbers, Ap, solar wind bulk speed ( V ), magnetic field ( B ), as well as to the cycle maximum (M), minimum (m), and the epochs of the solar polar field reversals. This enables us to derive the rigidity dependence of observations, and helps us to define the characteristics of the modulation function in the heliosphere.
Computational Modeling of Three-Dimensional Endwall Flow Through a Turbine Rotor Cascade With Strong Secondary Flows

A steady, three-dimensional Navier-Stokes solver that utilizes a pressure-based technique for incompressible flows is used to simulate the three-dimensional flow field in a turbine cascade. A new feature of the numerical scheme is the implementation of a second-order plus fourth-order artificial dissipation formulation, which provides a precise control of the numerical dissipation. A low-Reynolds-number form of a two-equation turbulence model is used to account for the turbulence effects. Comparison between the numerical predictions and the experimental data indicates that the numerical model is able to capture most of the complex flow phenomena in the endwall region of a turbine cascade, except the high gradient region in the secondary vortex core. The effects of inlet turbulence intensity and turbulence length scale on secondary vortices, total pressure loss, and turbulence kinetic energy inside the passage are presented and interpreted. It is found that higher turbulence intensity energizes the vortical motions and tends to move the passage vortex away from the endwall. With a larger turbulence length scale, the secondary flow inside the passage is reduced. However, the total pressure loss increases due to higher turbulence kinetic energy production.
The potential for bias in principal causal effect estimation when treatment received depends on a key covariate

Motivated by a potential-outcomes perspective, the idea of principal stratification has been widely recognized for its relevance in settings susceptible to posttreatment selection bias such as randomized clinical trials where treatment received can differ from treatment assigned. In one such setting, we address subtleties involved in inference for causal effects when using a key covariate to predict membership in latent principal strata. We show that when treatment received can differ from treatment assigned in both study arms, incorporating a stratum-predictive covariate can make estimates of the “complier average causal effect” (CACE) derive from observations in the two treatment arms with different covariate distributions. Adopting a Bayesian perspective and using Markov chain Monte Carlo for computation, we develop posterior checks that characterize the extent to which incorporating the pretreatment covariate endangers estimation of the CACE. We apply the method to analyze a clinical trial comparing two treatments for jaw fractures in which the study protocol allowed surgeons to overrule both possible randomized treatment assignments based on their clinical judgment and the data contained a key covariate (injury severity) predictive of treatment received.
Text windows and phrases differing by discipline, location in document, and syntactic structure

Knowledge of window style, content, location, and grammatical structure may be used to classify documents as originating within a particular discipline or may be used to place a document on a theory vs practice spectrum. This distinction is also studied here using the type-token ratio to differentiate between sublanguages. The statistical significance of windows is computed, based on the presence of terms in titles, abstracts, citations, and section headers, as well as binary-independent and inverse-document-frequency weightings. The characteristics of windows are studied by examining their within-window density and the S concentration, the concentration of terms from various document fields (e.g. title, abstract) in the fulltext. The rate of window occurrences from the beginning to the end of document fulltext differs between academic fields. Different syntactic structures in sublanguages are examined, and their use is considered for discriminating between specific academic disciplines and, more generally, between theory vs practice or knowledge vs applications-oriented documents.
Do markets respond to quality information? The case of fertility clinics

Although policymakers have increasingly turned to provider report cards as a tool to improve health care quality, existing studies provide mixed evidence on whether they influence consumer choices. We examine the effects of providing consumers with quality information in the context of fertility clinics providing Assisted Reproductive Therapies (ART). We report three main findings. First, clinics with higher birth rates had larger market shares after the adoption of report cards relative to before. Second, clinics with a disproportionate share of young, relatively easy-to-treat patients had lower market shares after adoption versus before. This suggests that consumers take into account information on patient mix when evaluating clinic outcomes. Third, report cards had larger effects on consumers and clinics from states with ART insurance coverage mandates. We conclude that consumers respond to quality report cards when choosing among providers of ART.
The environmental dependence of clustering in hierarchical models

In hierarchical models, density fluctuations on different scales are correlated. This induces correlations between dark halo masses, their formation histories, and their larger-scale environments. In turn, this produces a correlation between galaxy properties and environment. This correlation is entirely statistical in nature. We show how the observed clustering of galaxies can be used to quantify the importance of this statistical correlation relative to other physical effects which may also give rise to correlations between the properties of galaxies and their surroundings. We also develop a halo model description of this environmental dependence of clustering.
Lg attenuation in the central and eastern United States as revealed by the EarthScope Transportable Array

Abstract Lg waveforms recorded by EarthScope's Transportable Array (TA) are used to estimate Lg Q 0 in the central and eastern United States (CEUS). Attenuation is calculated based on Lg spectral amplitudes filtered at a narrow band from 0.5 to 1.5 Hz. Two-station and reverse two-station techniques are used to calculate Q 0 values. 39 events occurring from 2010 to 2012 and ranging from magnitude 3 to magnitude 6 are used in this study. 39,258 and 4,627 interstation Q 0 values are determined using the two-station and reverse two-station techniques, respectively. The results show northeast trending high Q 0 regions (low attenuation) ranging from eastern New Mexico to Wisconsin. Regions of low Q 0 (high attenuation) are seen along the Minnesota–Wisconsin border, the Gulf Coastal Plain (GCP), along the South Dakota–Nebraska border, and along the Oklahoma–Texas border. A positive correlation between heat flow, sediment thickness, recent tectonic activity, fluids, and low Q 0 was observed. Areas with low heat flow, thin sediment cover, no recent tectonic activity, and a lack of fluids were observed to have consistently high Q 0 . These new models use a greater amount of data, attain more coverage than previous studies, and better constrain attenuation. This increase in detail can improve high frequency ground motion predictions of future large earthquakes for more accurate far field hazard assessment and improve the overall understanding of the structure and assemblage of the CEUS.
A SEARCH FOR PHOTOMETRIC VARIABILITY IN L- AND T-TYPE BROWN DWARF ATMOSPHERES

Using the Gemini infrared camera on the 3 m Shane telescope at Lick Observatory, we have searched for broadband J and K' photometric variability for a sample of 15 L- and T-type brown dwarfs, including 7 suspected spectral binaries. Four of the dwarfs—2MASS J0939–2448, 2MASS J1416+1348A, 2MASS J1711+2232, and 2MASS J2139+0220—exhibit statistically significant variations over timescales ranging from ~0.5 hr to 6 days. Our detection of variability in 2MASS J2139+0220 confirms that reported by Radigan et al., and periodogram and phase dispersion minimization analysis also confirms a variability period of approximately 7.6 ± 0.2 hr. Remarkably, two of the four variables are known or candidate binary systems, including 2MASS J2139+0220, for which we find only marginal evidence of radial velocity variation over the course of a year. This result suggests that some spectral binary candidates may appear as such due to the blending of cloudy and non-cloudy regions in a single patchy atmosphere. Our results are consistent with an overall variability fraction of 35% ± 5%, with no clear evidence of greater variability among brown dwarfs at the L dwarf/T dwarf transition.
On-Line Paging Against Adversarially Biased Random Inputs

In evaluating an algorithm, worst-case analysis can be overly pessimistic. Average-case analysis can be overly optimistic. An intermediate approach shows that an algorithm does well on a broad class of input distributions. E. Koutsoupias and C. H. Papadimitriou (1994, in “Proc. of the 35th IEEE Annual Symp. on Foundation of Computer Science,” pp. 394?400, IEEE Press, New York) recently analyzed the least-recently-used (LRU) paging strategy in this manner, analyzing its performance on an input sequence generated by a so-called diffuse adversary?one that must choose each request probabilistically so that no page is chosen with probability more than some fixed ?0. They showed that LRU achieves the optimal competitive ratio (for deterministic on-line algorithms), but they did not determine the actual ratio. In this paper we estimate the optimal ratios within roughly a factor of two for both deterministic strategies and randomized strategies. Around the threshold ??1/k (where k is the cache size), the optimal ratios are both ?(lnk). Below the threshold the ratios tend rapidly to O(1). Above the threshold the ratio is unchanged for randomized strategies but tends rapidly to ?(k) for deterministic ones. We also show that the competitive ratios for First-in-first-out (FIFO) and Flush-when-full (FWF) are both k when ??1/k. In contrast, the ratio for LRU is less than 2lnk+4 when ?=1/k. It is folklore that LRU outperforms FIFO in practice, but to date the only other variant of competitive analysis in which LRU has been shown to outperform FIFO is the access graph model. For completeness, we give an alternate proof of the optimality of LRU.