cssi/SciSciGPT-SciSciNet huggingface dataset:
What Can America Learn from the British Tax System

This paper examines elements of British tax policy and discusses their implications for the US, where several recent proposals would mirror aspects of the British system. These include reducing filing requirements under the individual income tax, indexing capital gains for inflation, cutting mortgage interest deductions, enacting a value added tax, and integrating the corporate and personal income taxes. The paper also discusses implications of the poll tax for tax reform. Britain and America have made different choices involving equity, efficiency, simplicity and other goals. These choices offer the chance to help identify the impact of tax policy. JEL classification: H20.
Dislocation modeling of creep-related tilt changes

Tilt changes associated with 1–5 mm of fault creep have been detected at several different locations on the San Andreas fault on tiltmeters within 500 m of the creep observation point. The creep-related tilts have amplitudes of 0.5 μrad and durations comparable to the creep events. No changes $10−2 μrad have been observed on tiltmeters at distances $1 km from the fault at the time of the creep events. Dislocation models capable of replicating the creep-related tilt events have been constructed to examine the relationship of the model parameters to details of the tilt waveforms. The tilt time histories and bounded assumptions of the source-station configurations, and the displacement time history, can be used to infer the type and amount of displacement, the propagation direction and depth of the slip zone. The shallow depth and finite size of the slip zone indicated by these models constrasts with the horizontal extent.
DMP: Deterministic Shared-Memory Multiprocessing

Shared-memory multicore and multiprocessor systems are nondeterministic, which frustrates debugging and complicates testing of multithreaded code, impeding parallel programming's widespread adoption. The authors propose fully deterministic shared-memory multiprocessing that not only enhances debugging by offering repeatability by default, but also improves the quality of testing and the deployment of production code. They show that determinism can be provided with little performance cost on future hardware.
Intermediate mass dilepton production in heavy-ion collisions at SPS energies

Abstract Through the analysis of HELIOS-3 data on dilepton spectra, we demonstrate the importance of secondary processes for the dilepton production in heavy-ion collisions in the intermediate mass region. We find that, while the dilepton spectra in proton-induced reactions can be nicely explained by the decay of primary vector mesons, charmed hadrons, and initial Drell-Yan processes, the strong enhancement seen in the heavy-ion data comes mainly from the secondary meson-meson interactions which are unique to heavy collisions.
Thermodynamic Aspects of Tropical Cyclone Formation

AbstractThe thermodynamic aspects of tropical cyclone (TC) formation near the center of the wave pouch, a region of approximately closed Lagrangian circulation within the wave critical layer, are examined through diagnoses of a high-resolution numerical simulation and dropsonde data from a recent field campaign. It is found that the meso-β area near the pouch center is characterized by high saturation fraction, small difference in equivalent potential temperature θe between the surface and the middle troposphere, and a short incubation time scale. Updrafts tend to be more vigorous in this region, presumably because of reduced dry air entrainment, while downdrafts are not suppressed. The thermodynamic conditions near the pouch center are thus critically important for TC formation.The balanced responses to convective and stratiform heating at the pregenesis stage are examined using the Sawyer–Eliassen equation. Deep convection is concentrated near the pouch center. The strong radial and vertical gradients o...
Real-Time Inductive-Signature-Based Level of Service for Signalized Intersections

The Highway Capacity Manual (HCM) presents a procedure for estimating signalized intersection control delay, which is used to determine level of service (LOS) and to evaluate intersection performance. The HCM is used extensively by traffic engineers. However, it is intended as an offline decision support tool for planning and design. To meet user requirements of advanced traffic management and information systems, new LOS criteria are required for real-time intersection analysis. The objective of this research was to demonstrate a technique for development of such LOS criteria. The study used a new measure of effectiveness, called reidentification delay (RD), derived from analysis of vehicle inductive signatures and reidentification of vehicles traveling through a major signalized intersection in the city of Irvine, California. Two main issues regarding real-time LOS criteria were tackled. The first was how to determine the threshold values partitioning the LOS categories. To provide reliable real-time tr...
Impact of Race and Sex on Pain Management by Medical Trainees: A Mixed Methods Pilot Study of Decision Making and Awareness of Influence

Objective Previous research suggests female and black patients receive less optimal treatment for their chronic pain compared with male and white patients. Provider-related factors are hypothesized to contribute to unequal treatment, but these factors have not been examined extensively. This mixed methods investigation examined the influence of patients' demographic characteristics on providers' treatment decisions and providers' awareness of these influences on their treatment decisions. Methods Twenty medical trainees made treatment decisions (opioid, antidepressant, physical therapy) for 16 virtual patients with chronic low back pain; patient sex and race were manipulated across patients. Participants then indicated from a provided list the factors that influenced their treatment decisions, including patient demographics. Finally, individual interviews were conducted to discuss the role of patient demographics on providers' clinical decisions. Results Individual regression analyses indicated that 30% of participants were reliably influenced by patient sex and 15% by patient race when making their decisions (P < 0.05 or P < 0.10). Group analyses indicated that white patients received higher antidepressant recommendations, on average, than black patients (P < 0.05). Half of the medical trainees demonstrated awareness of the influence of demographic characteristics on their decision making. Participants, regardless of whether they were influenced by patients' demographics, discussed themes related to patient sex and race; however, participants' discussion of patient demographics in the interviews did not always align with their online study results. Conclusions These findings suggest there is a considerable variability in the extent to which medical trainees are influenced by patient demographics and their awareness of these decision making influences.
Stable and Efficient Representation Learning with Nonnegativity Constraints

Orthogonal matching pursuit (OMP) is an efficient approximation algorithm for computing sparse representations. However, prior research has shown that the representations computed by OMP may be of inferior quality, as they deliver suboptimal classification accuracy on several image datasets. We have found that this problem is caused by OMP's relatively weak stability under data variations, which leads to unreliability in supervised classifier training. We show that by imposing a simple nonnegativity constraint, this nonnegative variant of OMP (NOMP) can mitigate OMP's stability issue and is resistant to noise overfitting. In this work, we provide extensive analysis and experimental results to examine and validate the stability advantage of NOMP. In our experiments, we use a multi-layer deep architecture for representation learning, where we use K-means for feature learning and NOMP for representation encoding. The resulting learning framework is not only efficient and scalable to large feature dictionaries, but also is robust against input noise. This framework achieves the state-of-the-art accuracy on the STL-10 dataset.
Incentives for sabotage in vertically related industries

We show that the incentives of a vertically integrated supplier to “sabotage” the activities of downstream rivals can vary with both the type of sabotage and the nature of downstream competition. Cost-increasing sabotage is typically profitable under both Cournot and Bertrand competition. In contrast, demand-reducing sabotage is often profitable under Cournot competition, but unprofitable under Bertrand competition. Incentives for sabotage can vary non-monotonically with the degree of product differentiation.
A Human-Centered Framework for Ensuring Reliability on Crowdsourced Labeling Tasks

This paper describes an approach to improving the reliability of a crowdsourced labeling task for which there is no objective right answer. Our approach focuses on three contingent elements of the labeling task: data quality, worker reliability, and task design. We describe how we developed and applied this framework to the task of labeling tweets according to their interestingness. We use in-task CAPTCHAs to identify unreliable workers, and measure inter-rater agreement to decide whether subtasks have objective or merely subjective answers.
The mildly non-linear regime of structure formation

We present a simple physically motivated picture for the mildly non-linear regime of structure formation, which captures the effects of the bulk flows. We apply this picture to develop a method to significantly reduce the sample variance in cosmological N-body simulations at the scales relevant to the Baryon Acoustic Oscillations (BAO). The results presented in this paper will allow for a speed-up of an order of magnitude (or more) in the scanning of the cosmological parameter space using N-body simulations for studies which require a good handle of the mildly non-linear regime, such as those targeting the BAO. Using this physical picture we develop a simple formula, which allows for the rapid calculation of the mildly non-linear matter power spectrum to percent level accuracy, and for robust estimation of the BAO scale.
AGENCY COSTS AND INNOVATION

Abstract Stylized facts indicate that small firms are responsible for a disproportionate share of innovative research. There are many possible explanations for this fact. The paper seeks to understand this phenomenon as the outcome of an optimal assignment of tasks across individuals and organizations. It is shown that incentive costs associated with a given task depend on the total portfolio of tasks that an individual or an organization undertakes. Mixing hard to measure activities (innovation) with easy to measure activities (routine) is particularly costly, since it will either lead to misallocation of attention across tasks or to misallocation of risk. Larger firms are at a comparative disadvantage in conducting highly innovative research, because of the costs associated with managing a heterogeneous set of tasks. It is further argued that optimal organizational responses to coordination and control of routine tasks will lead to bureaucratization within the firm and to financial constraints imposed by capital markets, both of which are hostile to innovation.
Stability of quasi-Keplerian shear flow in a laboratory experiment

Subcritical transition to turbulence has been proposed as a source of turbulent viscosity required for the associated angular momentum transport for fast accretion in Keplerian disks. Previously cited laboratory experiments in supporting this hypothesis were performed either in a di erent type of flow than Keplerian or without quantitative measurements of angular momentum transport and mean flow profile, and all of them appear to su er from Ekman e ects, secondary flows induced by nonoptimal axial boundary conditions. Such Ekman e ects are expected to be absent from astronomical disks, which probably have stress-free vertical boundaries unless strongly magnetized. Aims. To quantify angular momentum transport due to subcritical hydrodynamic turbulence, if exists, in a quasi-Keplerian flow with minimized Ekman e ects. Methods.We perform a local measurement of the azimuthal-radial component of the Reynolds stress tensor in a novel laboratory apparatus where Ekman e ects are minimized by flexible control of axial boundary conditions. Results.We find significant Ekman e ects on angular momentum transport due to nonoptimal axial boundary conditions in quasi-Keplerian flows. With the optimal control of Ekman e ects, no statistically meaningful angular momentum transport is detected in such flows at Reynolds number up to two millions. Conclusions. Eithermore » a subcritical transition does not occur, or, if a subcritical transition does occur, the associated radial transport of angular momentum in optimized quasi-Keplerian laboratory flows is too small to directly support the hypothesis that subcritical hydrodynamic turbulence is responsible for accretion in astrophysical disks. Possible limitations in applying laboratory results to astrophysical disks due to experimental geometry are discussed.« less
Frequency Comb Velocity-Modulation Spectroscopy

We have demonstrated a new technique that provides massively parallel comb spectroscopy sensitive specifically to ions through the combination of cavity-enhanced direct frequency comb spectroscopy with velocity-modulation spectroscopy. Using this novel system, we have measured electronic transitions of ${\mathrm{HfF}}^{+}$ and achieved a fractional absorption sensitivity of $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ recorded over 1500 simultaneous channels spanning $150\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$ around 800 nm with an absolute frequency accuracy of 30 MHz ($0.001\text{ }\text{ }{\mathrm{cm}}^{\ensuremath{-}1}$). A fully sampled spectrum consisting of interleaved measurements is acquired in 30 min.
Observational evidence for an inside-out substorm onset scenario

Abstract. We present observations which provide strong support for a substorm expansion phase onset scenario in which a localized inner magnetospheric instability developed first and was later followed by the development of a Near Earth Neutral Line (NENL) farther down-tail. Specifically, we find that the onset began as a localized brightening of an intensified growth phase arc which developed as a periodic series of arc-aligned (i.e. azimuthally arrayed) bright spots. As the disturbance grew, it evolved into vortical structures that propagated poleward and eventually morphed into an east-west aligned arc system at the poleward edge of the auroral substorm bulge. The evolution of the auroral intensity is consistent with an exponential growth with an e-folding time of around 188 s (corresponding to a linear growth rate, γ of 5.33×10−3 s−1). During the initial breakup, no obvious distortions of auroral forms to the north were observed. However, during the expansion phase, intensifications of the poleward boundary of the expanding bulge were observed together with the equatorward ejection of auroral streamers into the bulge. A strong particle injection was observed at geosynchronous orbit, but was delayed by several minutes relative to onset. Ground magnetometer data also shows a two phase development of mid-latitude positive H-bays, with a quasi-linear increase in H between the onset and the injection. We conclude that this event provides strong evidence in favor of the so-called "inside-out" substorm onset scenario in which the near Earth region activates first followed at a later time by the formation of a near-to-mid tail substorm X-line. The ballooning instability is discussed as a likely mechanism for the initial onset.
Understanding human learning using a multi-agent simulation of the unified learning model

Within cognitive science, computational modeling based on cognitive architectures has been an important approach to addressing questions of human cognition and learning. This paper reports on a multi-agent computational model based on the principles of the Unified Learning Model (ULM). Derived from a synthesis of neuroscience, cognitive science, psychology, and education, the ULM merges a statistical learning mechanism with a general learning architecture. Description of the single agent model and the multi-agent environment which translate the principles of the ULM into an integrated computational model is provided. Validation results from simulations with respect to human learning are presented. Simulation suitability for cognitive learning investigations is discussed. Multi-agent system performance results are presented. Findings support the ULM theory by documenting a viable computational simulation of the core ULM components of long-term memory, motivation, and working memory and the processes taking place among them. Implications for research into human learning and intelligent agents are presented.
Wild wall crossing and BPS giants

We show that the BPS spectrum of pure SU(3) four-dimensional super Yang-Mills with $ \mathcal{N} $ = 2 supersymmetry exhibits a surprising phenomenon: there are regions of the Coulomb branch where the growth of the BPS degeneracies with the charge is exponential. We show this using spectral networks and independently using wall-crossing formulae and quiver methods. The computations using spectral networks provide a very nontrivial example of how these networks determine the four-dimensional BPS spectrum. We comment on some physical implications of the wild spectrum: for example, exponentially many field-theoretic BPS states with large charge are gigantic. Finally, we exhibit some surprising, thus far unexplained, regularities of the BPS spectrum.
Effects of Morphology on the Decohesion of Compressed Thin Films

Residually compressed thin films are susceptible to spalling from substrates. A prerequisite for this to occur is that a separation develops at the interface large enough to allow buckling. Thereafter, the mechanisms of spalling are well-established. In this article, the mechanics of formation of the initial separation are addressed. Perturbations on the interface are deemed responsible for this process. Calculations of energy release rates for various interface morphologies have revealed that aperiodic perturbations can initiate and extend the separations to a length sufficient for buckling. Conversely, periodic perturbations trap separations at dimensions too small to buckle. Illustrations are given for an alumina film (scale) on Ni-based superalloys. Implications for life prediction models are explored.
Measurement of Renal Functional Reserve in Children

Renal functional reserve was measured during 89 studies in 78 children as the difference between the baseline glomerular filtration rate (GFR) and that following a protein meal. GFR was measured using creatinine as the filtration marker in children pre-treated with cimetidine. The children had been on a diet free of meat, fish, and fowl for 24 h. The protein meal to stimulate GFR was derived from milk, cheese, eggs, and baked goods. The increase in GFR following the protein meal was due mainly to an increase in the glomerular filtration of creatinine, with a small contribution by decreased serum creatinine concentration. This study confirmed that renal functional reserve can be measured using a meat-free protein meal to stimulate GFR. The protocol employed is a relatively noninvasive and inexpensive procedure for identifying glomerular hyperfiltration in children.
Space Telescope Low-Scattered-Light Camera: A Model

A design approach for a camera to be used with the Space Telescope is given. Camera optics relay the system pupil onto an annular Gaussian ring apodizing mask to control diffracted light. Image plane intensity distributions for both one- and two-dimensional models of ripple on the primary mirror were calculated. Calculations using ripple amplitudes between X/20 and X/200 with spatial correlations of the ripple across the primary mirror between 0.2 and 2.0 cm indicate that the detection of an object 109 times fainter than a bright source in the field is possible. We thus conclude that detection of a Jovian-type planet in orbit about a Centauri with a camera on the Space Telescope may be possible.
Multiscale Superpixels and Supervoxels Based on Hierarchical Edge-Weighted Centroidal Voronoi Tessellation

Super pixels and super voxels play an important role in many computer vision applications, such as image segmentation, object recognition and video analysis. In this paper, we propose a hierarchical edge-weighted centroidal Voronoi tessellation (HEWCVT) method for generating superpixels/supervoxels in multiple scales. In this method we model the problem as a multilevel clustering process: superpixels/supervoxels in one level are clustered to obtain larger size superpixels/supervoxels in the next level. In the finest scale, the initial clustering is directly conducted on pixels/voxels. The clustering energy involves both color/feature similarities and the proposed boundary smoothness of superpixels/supervoxels. The resulting superpixels/supervoxels can be easily represented by a hierarchical tree which describes the nesting relation of superpixels/supervoxels across different scales. We evaluate and compare the proposed method with several state-of-the-art superpixel/supervoxel methods on standard image and video datasets. Both quantitative and qualitative results show that the proposed HEWCVT method achieves superior or comparable performances to other methods.
Molecular Similarity Analysis and Virtual Screening by Mapping of Consensus Positions in Binary-Transformed Chemical Descriptor Spaces with Variable Dimensionality

A novel compound classification algorithm is described that operates in binary molecular descriptor spaces and groups active compounds together in a computationally highly efficient manner. The method involves the transformation of continuous descriptor value ranges into a binary format, subsequent definition of simplified descriptor spaces, identification of consensus positions of specific compound sets in these spaces, and iterative adjustments of the dimensionality of the descriptor spaces in order to discriminate compounds sharing similar activity from others. We term this approach Dynamic Mapping of Consensus positions (DMC) because the definition of reference spaces is tuned toward specific compound classes and their dimensionality is increased as the analysis proceeds. When applied to virtual screening, sets of bait compounds are added to a large screening database to identify hidden active molecules. In these calculations, molecules that map to consensus positions after elimination of most of the ...
AC magnetic measurements of the ALS booster dipole engineering model magnet

Ten-Hertz sine wave and two-Hertz sawtooth AC magnetic measurements of the curved Advanced Light Source (ALS) booster dipole engineering model magnet have been accomplished. Long curved coils were utilized to measure the integral transfer function and uniformity. Point coils and a Hall probe were used to measure magnetic induction and its uniformity. The data were logged and processed by a Tektronix 11401 digital oscilloscope. The dependence of the effective length on the field was determined from the ratio of the integral coil signals to the point coil signals. Quadrupole and sextupole harmonics were derived from the point and integral uniformity measurements. The magnetic length and field uniformity values obtained demonstrate that the magnet design meets the specifications and qualify it for production. >
Characteristics of Grain Elevators that Contract with Railroads

The Staggers Rail Act of 1980 allowed contracts between railroads and shippers which have resulted in increased grain prices to some farmers while, at the same time, increasing competitive pressure on some local grain elevators. This study employs a logistic model designed for complex survey designs to identify characteristics of elevators that had railroad contracts during 1983–85. The total volume shipped from an elevator, number of railroads serving an elevator location, and affiliation with elevator firms serviced by more than one railroad company are found to contribute significantly to the probability of a grain elevator receiving a railroad contract.
Trend Toward Multiple Authors in Research Publications: Failure of the Universities to Support Research

In a previous letter to this column [Fraser-Smith, 1979] one of us drew attention to the marked decline since 1950 in the percentage of single-author papers in the Journal of Geophysical Research, 1, Space Physics (JGR 1) and the commensurate increase in the percentage of articles by three or more authors. The decline in single authors is certainly not confined to JGR 1, as is shown by more recent work (according to the Institute for Scientific Information, which indexes 2800 journals, the average number of authors per paper rose from 1.67 to 2.58 between 1960 and 1980) [Broad, 1981], so it seems clear that there is a widespread change taking place in the way scientists report the results of their research. It is perhaps important for us to point out that this is not an academic change; it is taking place right now, and most readers of this column are likely to be affected by it. There is undoubtedly an element of fashion involved in the decline of single authors, and it may well be that what we are all experiencing individually as scientists is a subtle process of rhinocerization, as described in the play by Ionesco [1960]. However, it would be unusual for a fashion to persist for 30 years or more unless other more substantive factors were involved. The question is, what are these factors?
Communication in industrial research laboratories

Industrial physicists publish their research results in internal company reports as well as in physics journals. In internal reports, research findings are communicated primarily to engineering and management groups. Because of the specific needs and preferences of these groups, the criteria for internal reports are different from those usually considered best for an outside publication. For the same reason, oral presentations in a company differ from those for a professional society meeting. The criteria for communication inside and outside a company are compared since physics graduates entering industry must be made aware of these differences — preferably before they graduate.
A smoothly parameterized family of stabilizable, observable linear systems containing realizations of all transfer functions of McMillan degree not exceeding n

It is shown that there is a continuously parameterized family F of n-dimensional single-input single-output (SISO) stabilizable detectable linear system Sigma (p) which contains at least one realization of each reduced, strictly proper transfer function of McMillan degree not exceeding n. The parameterization map p to Sigma (p) is a polynomial function in 2n indeterminates from an open convex polyhedron in R/sup 2n/ to the linear space of all SISO n-dimensional linear systems. >
The STRESS method for boundary-point performance analysis of end-to-end multicast timer-suppression mechanisms

The advent of multicast and the growth and complexity of the Internet has complicated network protocol design and evaluation. Evaluation of Internet protocols usually uses random scenarios or scenarios based on designers' intuition. Such an approach may be useful for average case analysis but does not cover boundary-point (worst or best case) scenarios. To synthesize boundary-point scenarios, a more systematic approach is needed. In this paper, we present a method for automatic synthesis of worst and best case scenarios for protocol boundary-point evaluation. Our method uses a fault-oriented test generation (FOTG) algorithm for searching the protocol and system state space to synthesize these scenarios. The algorithm is based on a global finite state machine (FSM) model. We extend the algorithm with timing semantics to handle end-to-end delays and address performance criteria. We introduce the notion of a virtual LAN to represent delays of the underlying multicast distribution tree. Our algorithms utilize implicit backward search using branch and bound techniques and start from given target events. As a case study, we use our method to evaluate variants of the timer suppression mechanism, used in various multicast protocols, with respect to two performance criteria: overhead of response messages and response time. Simulation results for reliable multicast protocols show that our method provides a scalable way for synthesizing worst case scenarios automatically. Results obtained using stress scenarios differ dramatically from those obtained through average case analyses. We hope for our method to serve as a model for applying systematic evaluation to other multicast protocols.
Dioxygen activation at monovalent nickel.

The monovalent oxidation state of nickel has received a growing amount of attention in recent years, in part due to its suggested catalytic role in a number of metalloprotein-mediated transformations. In coordination chemistry, nickel(I) is suitable for reductive activation of dioxygen, provided ligands are used that stabilize this less common oxidation state against disproportionation reactions. Two distinct molecular systems have been explored, which have provided access to new nickel–dioxygen structure types, namely, monomeric side-on and end-on superoxo and trans-μ-1,2-peroxo–dinickel complexes. The geometric and electronic structures of the complexes have been established by advanced spectroscopic methods, including resonance Raman and X-ray absorption spectroscopies, and augmented by density functional theory analyses.
UVOC-MAC: a MAC protocol for outdoor ultraviolet networks

As an alternative to radio-frequency (RF) communications, optical wireless communications can support high data rates and low power operations while providing good jamming resistance. Our focus in this paper is on deep ultraviolet (UV) outdoor communications (UVOC) where solar blind and non-line-of-sight operations are attractive. Light beams from UV light-emitting diode (LED) arrays serve as information carriers. In an abstract sense, this is similar to directional transmissions in RF; however, the physical (PHY) layer characteristics significantly differ due to atmospheric scattering. First, we perform extensive experiments on a UV testbed towards understanding signal propagation and the impact of the PHY on medium access. We find that UV propagation supports (a) fully duplex communications and (b) multiple data rate transmissions. Next, we propose a novel contention-based media access control (UVOC-MAC) protocol that inherently accounts for the UV PHY layer and fully exploits multi-fold spatial reuse opportunities. Evaluations via both simulations and analysis show that UVOC-MAC effectively mitigates collisions and achieves high throughput. In particular, up to a 4-fold increase in throughput and 50 % reduction in collision are possible compared to a MAC protocol agnostic to the UV PHY properties.
Temptation and Revealed Preference

Gul and Pesendorfer (2001) model the static behavior of an agent who ranks menus prior to the experience of temptation. This paper models the dynamic behavior of an agent whose ranking of menus itself is subject to temptation. The representation for the agent's dynamically inconsistent choice behavior views him as possessing a dynamically consistent view of what choices he "should" make (a normative preference) and being tempted by menus that contain tempting alternatives. Foundations for the model require a departure from Gul and Pesendorfer's idea that temptation creates a preference for commitment. Instead, it is hypothesized that distancing an agent from the consequences of his choices separates normative preference and temptation.
Integrating tax distortions and externality theory

Tax distortions are interpreted as fiscal externalities. By purchasing a taxed commodity, the individual generates tax revenue that is a benefit external to the purchaser. Behaving noncooperatively, the individual chooses a quantity that is less than the efficient level. The excess burden is interpreted as the benefit of choosing quantities cooperatively. The analysis clarifies the difference between the marginal cost of funds and the marginal excess burden, and explains the presence of compensated demands in the Harberger Triangle, in the Index of Discouragement, and in the Ramsey Equations.
Combinatorial Expansions in $K$-Theoretic Bases

We study the class $\mathcal C$ of symmetric functions whose coefficients in the Schur basis can be described by generating functions for sets of tableaux with fixed shape. Included in this class are the Hall-Littlewood polynomials, $k$-Schur functions, and Stanley symmetric functions; functions whose Schur coefficients encode combinatorial, representation theoretic and geometric information. While Schur functions represent the cohomology of the Grassmannian variety of $GL_n$, Grothendieck functions $\{G_\lambda\}$ represent the $K$-theory of the same space. In this paper, we give a combinatorial description of the coefficients when any element of $\mathcal C$ is expanded in the $G$-basis or the basis dual to $\{G_\lambda\}$.
Amyloid-Beta Protein Clearance and Degradation (ABCD) Pathways and their Role in Alzheimer's Disease

Amyloid-β proteins (Aβ) of 42 (Aβ42) and 40 aa (Aβ40) accumulate as senile plaques (SP) and cerebrovascular amyloid protein deposits that are defining diagnostic features of Alzheimer’s disease (AD). A number of rare mutations linked to familial AD (FAD) on the Aβ precursor protein (APP), Presenilin-1 (PS1), Presenilin- 2 (PS2), Adamalysin10, and other genetic risk factors for sporadic AD such as the e4 allele of Apolipoprotein E (ApoE-e4) foster the accumulation of Aβ and also induce the entire spectrum of pathology associated with the disease. Aβ accumulation is therefore a key pathological event and a prime target for the prevention and treatment of AD. APP is sequentially processed by β-site APP cleaving enzyme (BACE1) and γ-secretase, a multisubunit PS1/PS2-containing integral membrane protease, to generate Aβ. Although Aβ accumulates in all forms of AD, the only pathways known to be affected in FAD increase Aβ production by APP gene duplication or via base substitutions on APP and γ-secretase subunits PS1 and PS2 that either specifically increase the yield of the longer Aβ42 or both Aβ40 and Aβ42. However, the vast majority of AD patients accumulate Aβ without these known mutations. This led to proposals that impairment of Aβ degradation or clearance may play a key role in AD pathogenesis. Several candidate enzymes, including Insulin-degrading enzyme (IDE), Neprilysin (NEP), Endothelin-converting enzyme (ECE), Angiotensin converting enzyme (ACE), Plasmin, and Matrix metalloproteinases (MMPs) have been identified and some have even been successfully evaluated in animal models. Several studies also have demonstrated the capacity of γ-secretase inhibitors to paradoxically increase the yield of Aβ and we have recently established that the mechanism is by skirting Aβ degradation. This review outlines major cellular pathways of Aβ degradation to provide a basis for future efforts to fully characterize the panel of pathways responsible for Aβ turnover.
Circumglobal Teleconnection in the Northern Hemisphere Summer

Analysis of the 56-yr NCEP–NCAR reanalysis data reveals a recurrent circumglobal teleconnection (CGT) pattern in the summertime midlatitude circulation of the Northern Hemisphere. This pattern represents the second leading empirical orthogonal function of interannual variability of the uppertropospheric circulation. The CGT, having a zonal wavenumber-5 structure, is primarily positioned within a waveguide that is associated with the westerly jet stream. The spatial phases of CGT tend to lock to preferred longitudes. The geographically phase-locked patterns bear close similarity during June, August, and September, but the pattern in July shows shorter wavelengths in the North Pacific–North America sector. The CGT is accompanied by significant rainfall and surface air temperature anomalies in the continental regions of western Europe, European Russia, India, east Asia, and North America. This implies that the CGT may be a source of climate variability and predictability in the above-mentioned midlatitude regions. The CGT has significant correlations with the Indian summer monsoon (ISM) and El Nino–Southern Oscillation (ENSO). However, in normal ISM years the CGT–ENSO correlation disappears; on the other hand, in the absence of El Nino or La Nina, the CGT–ISM correlation remains significant. It is suggested that the ISM acts as a “conductor” connecting the CGT and ENSO. When the interaction between the ISM and ENSO is active, ENSO may influence northern China via the ISM and the CGT. Additionally, the variability of the CGT has no significant association with the Arctic Oscillation and the variability of the western North Pacific summer monsoon. The circulation of the wave train shows a barotropic structure everywhere except the cell located to the northwest of India, where a baroclinic circulation structure dominates. Two possible scenarios are proposed. The abnormal ISM may excite an anomalous west-central Asian high and downstream Rossby wave train extending to the North Pacific and North America. On the other hand, a wave train that is excited in the jet exit region of the North Atlantic may affect the westcentral Asian high and, thus, the intensity of the ISM. It is hypothesized that the interaction between the global wave train and the ISM heat source may be instrumental in maintaining the boreal summer CGT.
Features and Agreement

This paper compares the consistency-based account of agreement phenomena in 'unification-based' grammars with an implication-based account based on a simple feature extension to Lambek Categorial Grammar (LCG). We show that the LCG treatment accounts for constructions that have been recognized as problematic for 'unification-based' treatments.
Understanding Effect of Grain Boundaries in the Fracture Behavior of Polycrystalline Tungsten under Mode-I Loading

Polycrystalline tungsten is considered as an important material in aerospace, automobile, and energy industries due to its excellent thermal and mechanical properties. While grain boundaries (GBs) are perceived to play a major role in polycrystalline tungsten failure resistance, experimental data is scarce on explicit contribution of GBs to tungsten failure resistance. The present work focuses on understanding the effect of GB property variation on fracture resistance of polycrystalline tungsten. The cohesive finite element method is used for the simulation of crack propagation in polycrystalline tungsten microstructures. The results show a significant effect of GB property variation on change of crack propagation patterns during tungsten fracture. A variation of 10% in GB fracture energy resulted in distinctly different crack patterns with different primary crack propagation direction and the microcrack density. Based on the observed microstructural fracture attributes a relation between cohesive energy dissipation and microcrack density in polycrystalline tungsten microstructures is proposed.
SUPERSONIC SEPARATED AND REATTACHING LAMINAR FLOWS: I. GENERAL THEORY AND APPLICATION TO ADIABATIC BOUNDARY LAYER-SHOCK WAVE INTERACTIONS.

Abstract : The report deals with laminar boundary layer-shock wave interactions in which the pressure rise generated in an external supersonic, inviscid flow is communicated upstream through the boundary layer, and thereby induces flow separation. In order to describe this phenomenon approximately, including the subsequent reattachment of the flow, an integral or moment method is utilized in which the first moment of momentum is employed, in addition to the usual momentum integral (zeroth moment). The theoretical calculations agree quite well with the adiabatic laminar boundary layer-shock wave interaction experiments of Chapman and Hakkinen at moderate supersonic speeds. A comparison between the calculations and the experimental results of Sterrett and Emery on the free interaction upstream of a forward facing step at M = 6.5 also shows good agreement up to the plateau. The highly-cooled laminar boundary layer-shock wave interaction is qualitatively similar to the adiabatic turbulent boundary layer interaction. The limitations of the two-moment method based on a one parameter family of velocity profiles are discussed and the role of a two-moment, two-parameter method such as Wieghardt's is examined briefly.
Racial/Ethnic Threat and Federal Sentencing:

This study examines whether federal sentencing decisions are influenced by the racial/ethnic composition of federal court districts. Multilevel models of individual cases within federal judicial districts show that Black defendants receive moderately longer sentences than Whites, and that Hispanics and Whites receive similar sentences. These race/ethnicity effects on sentence length are found to vary across federal districts but not as predicted by racial threat theory. In contrast to racial threat predictions, Black sentence lengths are not significantly conditioned by the district Black population. Contrary to racial threat predictions, Hispanic defendants receive the harshest sentences when they account for the smallest share of the population (1 to 3 percent) and the most lenient sentences when they make up more sizable shares of district populations (more than 27 percent). Our results indicate that racial threat theory provides an inadequate explanation of how social contexts influence the federal se...
Evidence of Possible Induced Seismicity in the Wabash Valley Seismic Zone from Improved Microearthquake Locations

To evaluate the spatial structure of seismicity in the Wabash Valley of southern Indiana and Illinois, we analyzed data from a temporary seismic network that included 10 three-component, short-period seismometers and a 10-component dense phased array. We produced the first comprehensive catalog of local earth- quakes recorded during the 211-day deployment, from November 1995 through June 1996. The results are dominated by a cluster of 534 microearthquakes, with magni- tudes ranging from 0.6 to 1.8, near the town of New Harmony, Indiana, that were detected and recorded only by the phased array. The remarkable similarity of the cluster events in terms of waveform, magnitude, and temporal distribution suggests a tightly spaced grouping from a single seismic source. We relocated the earthquakes using improved relative arrival times of P and S waves computed by time-domain cross-correlation of the vertical beam traces and by complex cross-correlation of the horizontal beam traces, respectively. Additional constraints on absolute locations were applied using a graphical method of arrival-time difference analysis for six earthquakes recorded by two network stations outside the phased array. The resulting locations define a tight spatial grouping about a zone of post-Paleozoic faulting just west of the Indiana-Illinois border, in White County, Illinois. Average source depths from phased-array location methods and waveform modeling with synthetic seis- mograms indicate, in contrast to larger events in the region, that the earthquakes occurred at depths less than 4 km, within the sedimentary section of the Illinois Basin. We propose that these earthquakes are artificially induced events, likely related to water injection for the purpose of secondary recovery of petroleum in the Illinois Basin. The primary evidence for this includes: (1) tight spatial clustering of earth- quakes; (2) unusually shallow earthquake depths; (3) good spatial correlation of the relocated hypocenters to existing wells and oil fields; and (4) highly repetitive events with only a small range in magnitude.
A Dissipative Algorithm for Wave-like Equations in the Characteristic Formulation

We present a dissipative algorithm for solving nonlinear wave-like equations when the initial data is specified on characteristic surfaces. The dissipative properties built in this algorithm make it particularly useful when studying the highly nonlinear regime where previous methods have failed to give a stable evolution in three dimensions. The algorithm presented in this work is directly applicable to hyperbolic systems proper of electromagnetism, Yang?Mills, and general relativity theories. We carry out an analysis of the stability of the algorithm and test its properties with linear waves propagating on a Minkowski background and the scattering off a Scwharszchild black hole in general relativity.
Analysis of Bonded Joints in Vehicular Structures

Abstract : A linear elastic finite-element analysis is used to evaluate the behavior of an adhesive joint bonding a boron/epoxy composite to a metallic substrate. The adhesive layer is treated as a separate elastic medium of finite thick-ness in order to remove the stress singularity that exists when dissimilar materials are joined. Results are presented for a single lap joint and a smoothly tapered joint for two thicknesses of the adhesive layer. For the lap joint, peak shearing stress in the adhesive is located adjacent to the material with the lower modulus. The smoothly tapered joint is shown to have lower stresses and to be more efficient. Recommendations are given for alleviating stress concentrations and improving the design of bonded joints. (Author-PL)
Curved Hexagonal Packings of Equal Disks in a Circle

For each k‚ 1 and corresponding hexagonal number h.k/D 3k.kC 1/C 1, we introduce m.k/D maxf.ki 1/!=2; 1g packings of h.k/ equal disks inside a circle which we call the curved hexagonalpackings. The curved hexagonal packing of 7 disks (kD 1, m.1/D 1) is well known and one of the 19 disks (kD 2, m.2/D 1) has been previously conjectured to be optimal. New curved hexagonal packings of 37, 61, and 91 disks (kD 3, 4, and 5, m.3/D 1, m.4/D 3, and m.5/D 12) were the densest we obtained on a computer using a so-called "billiards" simulation algorithm. A curved hexagonal packing pattern is invariant under a 60 - rotation. For k !1, the density (covering fraction) of curved hexagonal packings tends to … 2 =12. The limit is smaller than the density of the known optimum disk packing in the infinite plane. We found disk configurations that are denser than curved hexagonal packings for 127, 169, and 217 disks (kD 6, 7, and 8). In addition to new packings for h.k/ disks, we present the new packings we found for h.k/C 1 and h.k/i 1 disks for k up to 5, i.e., for 36, 38, 60, 62, 90, and 92 disks. The additional packings show the "tightness" of the curved hexagonal pattern for k• 5: deleting a disk does not change the optimum packing and its quality significantly, but adding a disk causes a substantial rearrangement in the optimum packing and substantially decreases the quality.
Quantitative sensory testing: effect of site and pressure on vibration thresholds.

Abstract Objective : To determine the effect of different sites and locally applied pressure on vibration thresholds. Methods : Vibration thresholds were compared in 47 normal volunteers at 3 sites of the index finger (pulp, dorsum of the middle phalanx and nail) and at two sites of the great toe (dorsum of the proximal phalanx and nail). The effect of local pressure (30, 50 and 100 g/1.22 cm 2 ) were compared in 41 subjects at the dorsum of the middle phalanx of the index finger and the proximal phalanx of the great toe. Results : The hand was more sensitive than the foot for vibration. There were no significant differences in vibration thresholds at different sites of the index finger and different sites of the great toe. The pulp of the index finger yielded the least inter-individual variation. Testing under 30 and 50 g/1.22 cm 2 of pressure yielded equal vibration thresholds. Vibration threshold was higher when tested under 100 g/1.22 cm 2 at the index finger but not the great toe. This difference was small and clinically negligible. Conclusion : Testing of vibration thresholds in normal subjects can be adequately conducted at several sites of the index finger and the great toe. The test can be adequately done under low pressure of 30–50 g/1.22 cm 2 .