cssi/SciSciGPT-SciSciNet huggingface dataset:
Acid hydrolysis of easily dispersed and microaggregate-derived silt- and clay-sized fractions to isolate resistant soil organic matter

The current paradigm in soil organic matter (SOM) dynamics is that the proportion of biologically resistant SOM will increase when total SOM decreases. Recently, several studies have focused on identifying functional pools of resistant SOM consistent with expected behaviours. Our objective was to combine physical and chemical approaches to isolate and quantify biologically resistant SOM by applying acid hydrolysis treatments to physically isolated silt- and clay-sized soil fractions. Microaggegrate-derived and easily dispersed silt- and clay-sized fractions were isolated from surface soil samples collected from six long-term agricultural experiment sites across North America. These fractions were hydrolysed to quantify the non-hydrolysable fraction, which was hypothesized to represent a functional pool of resistant SOM. Organic C and total N concentrations in the four isolated fractions decreased in the order: native > no-till > conventional-till at all sites. Concentrations of non-hydrolysable C (NHC) and N (NHN) were strongly correlated with initial concentrations, and C hydrolysability was found to be invariant with management treatment. Organic C was less hydrolysable than N, and overall, resistance to acid hydrolysis was greater in the silt-sized fractions compared with the clay-sized fractions. The acid hydrolysis results are inconsistent with the current behaviour of increasing recalcitrance with decreasing SOM content: while %NHN was greater in cultivated soils compared with their native analogues, %NHC did not increase with decreasing total organic C concentrations. The analyses revealed an interaction between biochemical and physical protection mechanisms that acts to preserve SOM in fine mineral fractions, but the inconsistency of the pool size with expected behaviour remains to be fully explained.
Information processing during transient responses in the crayfish visual system

We analyzed sustaining fiber responses in the crayfish visual system to light pulses using information processing techniques. The light pulse stimuli elicited a transient and a steadystate component in the EPSP input and in the firing rate of the spike train output. The overall information transfer of the system was very low (˜ ), with a sharp increase during the transient portion of the response followed by a steady decrease. The information transfer dynamics are consistent with a simple spike generator model that depends explicitly on stimulus changes. The present analysis also corroborates the observed light reflex behavior.
Fluid permeabilities of triply periodic minimal surfaces.

It has recently been shown that triply periodic two-phase bicontinuous composites with interfaces that are the Schwartz primitive (P) and diamond (D) minimal surfaces are not only geometrically extremal but extremal for simultaneous transport of heat and electricity. The multifunctionality of such two-phase systems has been further established by demonstrating that they are also extremal when a competition is set up between the effective bulk modulus and electrical (or thermal) conductivity of the bicontinuous composite. Here we compute the fluid permeabilities of these and other triply periodic bicontinuous structures at a porosity $\ensuremath{\phi}=1∕2$ using the immersed-boundary finite-volume method. The other triply periodic porous media that we study include the Schoen gyroid (G) minimal surface, two different pore-channel models, and an array of spherical obstacles arranged on the sites of a simple cubic lattice. We find that the Schwartz P porous medium has the largest fluid permeability among all of the six triply periodic porous media considered in this paper. The fluid permeabilities are shown to be inversely proportional to the corresponding specific surfaces for these structures. This leads to the conjecture that the maximal fluid permeability for a triply periodic porous medium with a simply connected pore space at a porosity $\ensuremath{\phi}=1∕2$ is achieved by the structure that globally minimizes the specific surface.
A fundamental limitation of linearized algorithms for diffuse optical tomography.

Diffuse Optical Tomography is rapidly developing as a new imaging modality for characterizing the spatially varying optical properties of media which strongly scatter light (e.g. tissue). Numerous imaging algorithms exist, and more are being developed. Many of these algorithms rely on assumptions which linearize the relationship between the optical contrast and the perturbed signal. We show that this linear approximation makes quantitative imaging of spatially varying optical properties impossible. The explanation for this result is presented and the implication for Diffuse Optical Tomography is discussed.
Transverse multibunch bursting instability in the APS storage ring

The horizontal bursting instability was first observed in a single bunch in the Advanced Photon Source (APS) soon after operation began. Above the instability threshold, the bursting is characterized by exponentially growing bunch centroid oscillations whose amplitude saturates, then decays, repeating quasi-periodically. More recently, bursting was also observed with multiple bunches in both the horizontal and vertical planes, showing that this is not purely a single-bunch phenomenon. On the other hand, the multibunch instability threshold is strongly dependent on bunch spacing, and the dependence is markedly different for the two transverse planes. Depending on the bunch spacing, the bunch-to-bunch oscillations are sometimes coupled, sometimes not. In this paper, we discuss the threshold in terms of the chromaticity required to stabilize the beam. We present instability imaging data using a streak camera that shows the bunch-to-bunch oscillation phase, and turn-by-turn beam position histories that give the bursting time dependence for different bunch spacings. Finally, we discuss the machine impedance and measured tune shift with current.
Accelerated Bergman cyclization of porphyrinic-enediynes

The Bergman cyclization of simple diethynylporphyrinic-enediynes exhibits a double activation barrier to the formation of Bergman cyclized product. Addition of H-atom acceptor accelerates the formation of the picenoporphyrin, indicating that the second barrier is rate limiting.
How Victimized Drug Traders Mobilize Police

Illicit drug traders are more likely to be victimized because they cannot report crimes committed against them to the police. Their inability to access law is seen as a major precipitating factor in retaliatory violence. But, as we demonstrate, sometimes victimized drug traders do ask for formal mediation. Based on evidence from prior research combined with experiences recounted to us in the course of interviewing twenty-five unincarcerated drug dealers, we propose a typology of how this happens. We suggest that victimized drug traders mobilize the police in four conceptually distinct ways: “BSing”; getting over; criminal concealment; and criminal disclosure. Our typology provides the empirical grounding for future work aimed at theorizing this behavior and for reducing retaliatory violence by enhancing victimized criminals’ access to law. We conclude by discussing the relevance of our “inconvenient” results for the broader ethnographic audience.
Influencing the Bureaucracy: The Irony of Congressional Oversight

Does the president or Congress have more influence over policymaking by the bureaucracy? Despite a wealth of theoretical guidance, progress on this important question has proven elusive due to competing theoretical predictions and severe difficulties in measuring agency influence and oversight. We use a survey of federal executives to assess political influence, congressional oversight, and the policy preferences of agencies, committees, and the president on a comparable scale. Analyzing variation in political influence across and within agencies reveals that Congress is less influential relative to the White House when more committees are involved. While increasing the number of involved committees may maximize the electoral benefits for members, it may also undercut the ability of Congress as an institution to collectively respond to the actions of the presidency or the bureaucracy.
REFORMULATING THE COMMONS

The western hemisphere is richly endowed with a diversity of natural resource systems that are governed by complex local and national institutional arrangements that have not, until recently, been well understood. While many local communities that possess a high degree of autonomy to govern local resources have been highly successful over long periods of time, others fail to take action to prevent overuse and degradation of forests, inshore fisheries, and other natural resources. The conventional theory used to predict and explain how local users will relate to resources that they share makes a uniform prediction that users themselves will be unable to extricate themselves from the tragedy of the commons. Using this theoretical view of the world, there is no variance in the performance of self-organized groups. In theory, there are no self-organized groups. Empirical evidence tells us, however, that considerable variance in performance exists and many more local users self-organize and are more successful than it is consistent with the conventional theory . Parts of a new theory are presented here.
Positron Emission Mammography imaging

This paper examines current trends in Positron Emission Mammography (PEM) instrumentation and the performance tradeoffs inherent in them. The most common geometry is a pair of parallel planes of detector modules. They subtend a larger solid angle around the breast than conventional PET cameras, and so have both higher efficiency and lower cost. Extensions to this geometry include encircling the breast, measuring the depth of interaction (DOI), and dual-modality imaging (PEM and X-ray mammography, as well as PEM and X-ray guided biopsy). The ultimate utility of PEM may not be decided by instrument performance, but by biological and medical factors, such as the patient to patient variation in radiotracer uptake or the as yet undetermined role of PEM in breast cancer diagnosis and treatment.
Stabilization in the braid groups I: MTWS

Choose any oriented link type X and closed braid representatives X+,X− of X, where X− has minimal braid index among all closed braid representatives of X. The main result of this paper is a ‘Markov theorem without stabilization’. It asserts that there is a complexity function and a finite set of ‘templates’ such that (possibly after initial complexity-reducing modifications in the choice of X+ and X− which replace them with closed braids X+′,X−′) there is a sequence of closed braid representatives X+′=X1→X2→⋯→Xr=X−′ such that each passage Xi→Xi+1 is strictly complexity reducing and non-increasing on braid index. The templates which define the passages Xi→Xi+1 include 3 familiar ones, the destabilization, exchange move and flype templates, and in addition, for each braid index m≥4 a finite set T(m) of new ones. The number of templates in T(m) is a non-decreasing function of m. We give examples of members of T(m),m≥4, but not a complete listing. There are applications to contact geometry, which will be given in a separate paper.
Magnetoresistance in Thin Films of Silver Chalcogenides

Oriented and non-oriented thin films of silver(I) telluride, Ag2Te, were prepared by e-beam evaporation, vapor transport technique and Chemical Vapor Deposition (CVD). Crystallinity and orientation of the films were studied by Θ−2Θ XRD, rocking curve and pole figure measurements. The origin and conditions for the oriented growth are discussed. Special microdevice was prepared by photolitography from the oriented films of Ag2Te in order to investigate magnetoresistance (MR) in this material. It was proved that the reported earlier negative MR in Ag2Te films is a completely geometrical effect, which can be observed using non-linear arrangement of current and voltage contacts.
Longest prefix matching using bloom filters

We introduce the first algorithm that we are aware of to employ Bloom filters for longest prefix matching (LPM). The algorithm performs parallel queries on Bloom filters, an efficient data structure for membership queries, in order to determine address prefix membership in sets of prefixes sorted by prefix length. We show that use of this algorithm for Internet Protocol (IP) routing lookups results in a search engine providing better performance and scalability than TCAM-based approaches. The key feature of our technique is that the performance, as determined by the number of dependent memory accesses per lookup, can be held constant for longer address lengths or additional unique address prefix lengths in the forwarding table given that memory resources scale linearly with the number of prefixes in the forwarding table. Our approach is equally attractive for Internet Protocol Version 6 (IPv6) which uses 128-bit destination addresses, four times longer than IPv4. We present a basic version of our approach along with optimizations leveraging previous advances in LPM algorithms. We also report results of performance simulations of our system using snapshots of IPv4 BGP tables and extend the results to IPv6. Using less than 2 Mb of embedded RAM and a commodity SRAM device, our technique achieves average performance of one hash probe per lookup and a worst case of two hash probes and one array access per lookup.
An integrated mobile robot path (re)planner and localizer for personal robots

We describe a method for navigation in a known indoor environment, such as a home or office, that requires only inexpensive range sensors. Our framework includes a high-level planner which integrates and coordinates path planning and localization modules with the aid of a module for computing regions which are expected, with high probability, to contain the robot at any given time. The localization method is based on simple geometric properties of the environment which are computed during a preprocessing stage. The roadmap-based path planner enables one to select routes, and subgoals along those routes, that will facilitate localization and other optimization criteria. In addition, our framework enables one to quickly plan new routes, dynamically, based on the current position as computed by intermediate localization operations. We present simulation and hardware experimental results that illustrate the practicality and potential of our approach.
Synthetic biology: understanding biological design from synthetic circuits

An important aim of synthetic biology is to uncover the design principles of natural biological systems through the rational design of gene and protein circuits. Here, we highlight how the process of engineering biological systems - from synthetic promoters to the control of cell-cell interactions - has contributed to our understanding of how endogenous systems are put together and function. Synthetic biological devices allow us to grasp intuitively the ranges of behaviour generated by simple biological circuits, such as linear cascades and interlocking feedback loops, as well as to exert control over natural processes, such as gene expression and population dynamics.
Static-electric-field effects on high harmonic generation.

High harmonic generation in the presence of a static electric field is analyzed theoretically by an extension of the zero-range potential model treatment of Becker et al. [Phys. Rev. A 50, 1540 (1994)]. For ${\mathrm{H}}^{\ensuremath{-}}$ and a C${\mathrm{O}}_{2}$ laser of 5 \ifmmode\times\else\texttimes\fi{} ${10}^{10}$ W/${\mathrm{cm}}^{2}$ intensity, a static electric field of 100 kV/cm is shown to produce a plateau from the 3rd to the 23rd harmonic in which neighboring even and odd harmonics are of comparable intensity. Furthermore, odd harmonics on the plateau are one or more orders of magnitude more intense than in the absence of the static electric field. Dependence of emission rates on laser intensity and results for harmonic generation by Ar are also presented.
Stereoselective glycosylations of 2-azido-2-deoxy-glucosides using intermediate sulfonium ions.

TMSOTf-promoted glycosylations of 2-azido-2-deoxy-glucosyl trichloroacetimidates provide excellent α-anomeric selectivities when performed at a relatively high reaction temperature in the presence of PhSEt or thiophene. NMR and computation studies have shown that these glycosylations proceed through an equatorial anomeric sulfonium ion, which upon displacement by a sugar alcohol provides an axial glycoside. Computational studies have indicated that steric factors determine the selective formation of the β-anomeric sulfonium ion.
Dynamic Control of a Multiclass Queue with Thin Arrival Streams

As a model of make-to-order production, we consider an admission control problem for a multiclass, single-server queue. The production system serves multiple demand streams, each having a rigid due-date lead time. To meet the due-date constraints, a system manager may reject orders when a backlog of work is judged to be excessive, thereby incurring lost revenues. The system manager strives to minimize long-run average lost revenues by dynamically making admission control and sequencing decisions. Under heavy-traffic conditions the scheduling problem is approximated by a Brownian control problem, which is solved explicitly. Interpreting this solution in the context of the original queueing system, a nested threshold policy is proposed. A simulation experiment is performed to demonstrate the effectiveness of this policy.
Global Second Derivative Estimates for the Second Boundary Value Problem of the Prescribed Affine Mean Curvature and Abreu's Equations

In this paper, we prove the global second derivative estimates for the second boundary value problem of the prescribed affine mean curvature equation, where the affine mean curvature is only assumed to be in L p . Our result extends previous result by Trudinger and Wang in the case of globally bounded affine mean curvature and also covers Abreu’s equation.
Extrapolating histone marks across developmental stages, tissues, and species: an enhancer prediction case study

Dynamic activation and inactivation of gene regulatory DNA produce the expression changes that drive the differentiation of cellular lineages. Identifying regulatory regions active during developmental transitions is necessary to understand how the genome specifies complex developmental programs and how these processes are disrupted in disease. Gene regulatory dynamics are mediated by many factors, including the binding of transcription factors (TFs) and the methylation and acetylation of DNA and histones. Genome-wide maps of TF binding and DNA and histone modifications have been generated for many cellular contexts; however, given the diversity and complexity of animal development, these data cover only a small fraction of the cellular and developmental contexts of interest. Thus, there is a need for methods that use existing epigenetic and functional genomics data to analyze the thousands of contexts that remain uncharacterized. To investigate the utility of histone modification data in the analysis of cellular contexts without such data, I evaluated how well genome-wide H3K27ac and H3K4me1 data collected in different developmental stages, tissues, and species were able to predict experimentally validated heart enhancers active at embryonic day 11.5 (E11.5) in mouse. Using a machine-learning approach to integrate the data from different contexts, I found that E11.5 heart enhancers can often be predicted accurately from data from other contexts, and I quantified the contribution of each data source to the predictions. The utility of each dataset correlated with nearness in developmental time and tissue to the target context: data from late developmental stages and adult heart tissues were most informative for predicting E11.5 enhancers, while marks from stem cells and early developmental stages were less informative. Predictions based on data collected in non-heart tissues and in human hearts were better than random, but worse than using data from mouse hearts. The ability of these algorithms to accurately predict developmental enhancers based on data from related, but distinct, cellular contexts suggests that combining computational models with epigenetic data sampled from relevant contexts may be sufficient to enable functional characterization of many cellular contexts of interest.
Matrix Completion From a Few Entries

Let M be an n? × n matrix of rank r, and assume that a uniformly random subset E of its entries is observed. We describe an efficient algorithm, which we call OptSpace, that reconstructs M from |E| = O(rn) observed entries with relative root mean square error 1/2 RMSE ? C(?) (nr/|E|)1/2 with probability larger than 1 - 1/n3. Further, if r = O(1) and M is sufficiently unstructured, then OptSpace reconstructs it exactly from |E| = O(n log n) entries with probability larger than 1 - 1/n3. This settles (in the case of bounded rank) a question left open by Candes and Recht and improves over the guarantees for their reconstruction algorithm. The complexity of our algorithm is O(|E|r log n), which opens the way to its use for massive data sets. In the process of proving these statements, we obtain a generalization of a celebrated result by Friedman-Kahn-Szemeredi and Feige-Ofek on the spectrum of sparse random matrices.
Developing and fully developed turbulent flow in ribbed channels

Wall-mounted roughness features, such as ribs, are often placed along the walls of a channel to increase the convective surface area and to augment heat transfer and mixing by increasing turbulence. Depending on the relative roughness size and orientation, the ribs also have varying degrees of increased pressure losses. Designs that use ribs to promote heat transfer encompass the full range of having only a few streamwise ribs, which do not allow fully developed flow conditions, to multiple streamwise ribs, which do allow the flow to become fully developed. The majority of previous studies have focused on perturbing the geometry of the rib with little attention to the spatially and temporally varying flow characteristics and their dependence on the Reynolds number. A staggered rib-roughened channel study was performed using time-resolved digital particle image velocimetry (TRDPIV). Both the developing (entry region) and a fully developed region were interrogated for three Reynolds numbers of 2,500, 10,000, and 20,000. The results indicate that the flow was more sensitive to Reynolds number at the inlet than within the fully developed region. Despite having a similar mean-averaged flowfield structure over the full Reynolds number range investigated, the population and distribution of coherent structures and turbulent dissipation within the fully developed region were also found to be Reynolds number dependent. Exploring the time-accurate flow characteristics revealed that in addition to vortices shed from the rib shear layer, the region of the rib wake was governed by a periodic process of bursting of the wake vortices resulting in the intermittent ejection of the inter-rib recirculation region into the core flow. This periodic process was the driving mechanism resulting in mixing and heat transfer augmentation. A quadrant-splitting burst analysis was also performed to determine the characteristic frequency and duration of inter-rib bursting as well as the wake shedding frequency, both of which were determined to be Reynolds number dependent.
Identifying proteins of high designability via surface‐exposure patterns

Using an off-lattice model, we fully enumerate folded conformations of polypeptide chains of up to N = 19 monomers. Structures are found to differ markedly in designability, defined as the number of sequences with that structure as a unique lowest-energy conformation. We find that designability is closely correlated with the pattern of surface exposure of the folded structure. For longer chains, complete enumeration of structures is impractical. Instead, structures can be randomly sampled, and relative designability estimated either from designability within the random sample, or directly from surface-exposure pattern. We compare the surface-exposure patterns of those structures identified as highly designable to the patterns of naturally occurring proteins.
The cluster graphical lasso for improved estimation of Gaussian graphical models

The task of estimating a Gaussian graphical model in the high-dimensional setting is considered. The graphical lasso, which involves maximizing the Gaussian log likelihood subject to a lasso penalty, is a well-studied approach for this task. A surprising connection between the graphical lasso and hierarchical clustering is introduced: the graphical lasso in effect performs a two-step procedure, in which (1) single linkage hierarchical clustering is performed on the variables in order to identify connected components, and then (2) a penalized log likelihood is maximized on the subset of variables within each connected component. Thus, the graphical lasso determines the connected components of the estimated network via single linkage clustering. The single linkage clustering is known to perform poorly in certain finite-sample settings. Therefore, the cluster graphical lasso, which involves clustering the features using an alternative to single linkage clustering, and then performing the graphical lasso on the subset of variables within each cluster, is proposed. Model selection consistency for this technique is established, and its improved performance relative to the graphical lasso is demonstrated in a simulation study, as well as in applications to a university webpage and a gene expression data sets.
INTERNATIONAL YEAR OF ASTRONOMY INVITED REVIEW ON EXOPLANETS

Just 14 years ago the Solar System represented the only known planetary system in the Galaxy, and conceptions of planet formation were shaped by this sample of one. Since then, 320 planets have been discovered orbiting 276 individual stars. This large and growing ensemble of exoplanets has informed theories of planet formation, placed the Solar System in a broader context, and revealed many surprises along the way. In this review I provide an overview of what has been learned from studies of the occurrence, orbits, and physical structures of exoplanets. After taking a look back at how far the field has advanced, I will discuss some of the future directions of exoplanetary science, with an eye toward the detection and charactarization of Earth-like planets around other stars.
Multimedia Applications of Multiprocessor Systems-on-Chips

The paper surveys the characteristics of multimedia systems. Multimedia applications today are dominated by compression and decompression, but multimedia devices must also implement many other functions, such as security and file management. We introduce some basic concepts of multimedia algorithms and the larger set of functions that multimedia systems-on-chips must implement.
Continuance in expertise-sharing networks: a social perspective

As engineering firms, RD 2) system-mediated relationships with other users of the system increase continuance; and 3) investments in personalization of a system initially diminish continuance. Another notable contribution is the development and validation of several new measures for expertise-sharing network constructs.
A simultaneous model of household activity participation and trip chain generation

Abstract A trip generation model has been developed using a time-use perspective, in which trips are generated in conjunction with out-of-home activities, and time spent traveling is another component of overall time use. The model jointly forecasts three sets of endogenous variables – (1) activity participation and (2) travel time (together making up total out-of-home time use), and (3) trip generation – as a function of household characteristics and accessibility indices. It is estimated with data from the Portland, Oregon 1994 Activity and Travel Survey. Results show that the basic model, which has 10 endogenous time use and trip generation variables and 13 exogenous variables, fits well, and all postulated relationships are upheld. Test show that the basic model, which divides activities into work and nonwork, can be extended to a three-way breakdown of subsistence, discretionary and obligatory activities. The model can also capture the effects of in-home work on trip chaining and activity participation. We use the model to explore the effects on time use and trip chaining of GIS-based and zone-based accessibility indices.
Breaking Legal Inequality Traps: New Approaches to Building Justice Systems for the Poor in Developing Countries

There has long been broad agreement on the importance of building and enhancing access to 'rule of law' systems in developing countries, but efforts to do either of these things have an unhappy history. These failures, we suggest, are largely a product of a flawed theory of what 'law', 'justice' and 'institutions' are, how they come to take the form they do, and thus how they can be established elsewhere. This theory of institutional reform, however, and the assumptions on which it rests, is not confined to the legal 'sector', but to this day pervades and is reinforced by our prevailing development discourse and practice, most obviously with respect to the status of categories such as 'social development' and imperatives to seek straightforward 'policy implications' of social research. We outline the core tenants and assumptions of this theory, and show how its deployment in 'legal judicial reform' has underpinned successive waves of disappointing outcomes. We also outline an alternative theory, and show how it is informing a new generation of innovative efforts to improve the accessibility, legitimacy and effectiveness of justice systems for the poor.
Arabinofuranosides from mycobacteria: Synthesis of a highly branched hexasaccharide and related fragments containing β-arabinofuranosyl residues

The synthesis of 11 oligosaccharides (4−14) containing β-arabinofuranosyl residues is reported. The glycans are all fragments of two polysaccharides, arabinogalactan and lipoarabinomannan, which are found in the cell wall complex of mycobacteria. In the preparation of the targets, the key step was a low-temperature glycosylation reaction that installed the β-arabinofuranosyl residues with good to excellent stereocontrol.
Corporate Governance and Public Corruption

Corporate governance in the private sector and corruption are important for economic development and private sector development. This paper investigates how corporate governance in private-sector media companies can affect public corruption. The analytical framework, based on models of corporate governance, identifies two channels through which media ownership concentration affects corruption: an owner effect, which discourages corruption and a competition-for-control effect that enhances it. When the ownership structure of a newspaper has a majority shareholder, the first effect dominates and corruption decreases as ownership becomes more concentrated in the hands of majority shareholders. Without majority shareholders, the competition-for-control effect dominates and corruption increases with the concentration of ownership of the media company. Thus, the paper shows that cases of intermediate media-ownership concentration are the worst at promoting public accountability, while extreme situations, where the ownership is completely concentrated or widely held, can result in similar and lower levels of corruption.
Synthesis and Thermal Stability Studies of CaFe4As3

CaFe4As3 is a new intermetallic structure type that can be described as a framework comprising of FeAs4 tetrahedra. The structure has similarities to the 1-2-2 superconducting phase in that the Fe/As network is related to the ThCr2Si2 structure. In addition, this phase shows magnetic transitions associated with spin density waves. This phase was prepared from a Sn flux, and it has recently been reported that further expansion of this structure type via chemical substitution is limited. We have developed a solid-state synthesis route for the preparation of CaFe4As3 that involves reacting a stoichiometric combination of the constituent elements. The thermal stability of this material was investigated over the 298–1473 K temperature range. An initial investigation of the Sn grown CaFe4As3 crystals showed that residual Sn that was present on the surface of the crystals reacted with the crystals at temperatures above 1173 K to form new phases. A thermal stability study of Sn-free CaFe4As3 indicated that it decomposed to give CaFe2As2 and Fe2As. The thermal behavior of CaFe2As2 was also investigated and the data showed that it can also form CaFe4As3 at high temperatures. The solid-state synthesis route presented herein and additional solid solution studies may provide opportunities for the prepartion of materials with this structure type with improved electronic properties.
The Police and the Emotionally Disturbed: A Psychoanalytic Theory of Intervention

Psychoanalytic theory is applied to police crisis situations involving the mentally disturbed. After noting shortcomings of the traditional, commonsensical ways of dealing with such individuals, a discussion of thestrengths of a psychoanalytic method ispresented. It is argued thatpolice officers can achieve greater control in a psychiatric disturbance situation if they conceive of and treat the person more like a system offorces than a set ofpersonality characteristics. Concrete examples are discussed illustrating the method advocated.
Statistical topological data analysis using persistence landscapes

We define a new topological summary for data that we call the persistence landscape. Since this summary lies in a vector space, it is easy to combine with tools from statistics and machine learning, in contrast to the standard topological summaries. Viewed as a random variable with values in a Banach space, this summary obeys a strong law of large numbers and a central limit theorem. We show how a number of standard statistical tests can be used for statistical inference using this summary. We also prove that this summary is stable and that it can be used to provide lower bounds for the bottleneck and Wasserstein distances.
Health Care Spending: Historical Trends and New Directions

Over the past five decades, broad changes in the US health care system have dramatically influenced growth in health care expenditures. This review identifies the salient factors driving the growth of medical expenditures and how they influenced the trajectory of health economics research. We find that the research identified—and was strongly influenced by—four eras of expenditure growth: period 1, coverage expansion; period 2, experimentation with financial incentives; period 3, the managed care backlash; and period 4, a golden era of declining expenditure growth. We conclude by discussing some themes from this research suggesting optimism that, going forward, we can curb excess expenditure growth above GDP growth without harming population health.
Index structures for information filtering under the vector space model

The authors study what data structures and algorithms can be used to efficiently perform large-scale information filtering under the vector space model, a retrieval model established as being effective. They apply the idea of the standard inverted index to index user profiles. They devise an alternative to the standard inverted index, in which they, instead of indexing every term in a profile, select only the significant ones to index. They evaluate their performance and show that the indexing methods require orders of magnitude fewer I/Os to process a document than when no index is used. They also show that the proposed alternative performs better in terms of I/O and CPU processing time in many cases. >
Coupled plasticity and damage modeling and their applications in a three-dimensional Eulerian hydrocode

Abstract Previously developed constitutive models and solution algorithms for continuum-level anisotropic elastoplastic material strength and an isotropic damage model TEPLA have been implemented in the three-dimensional Eulerian hydrodynamics code known as CONEJO. The anisotropic constitutive modeling is posed in an unrotated material frame of reference using the theorem of polar decomposition to compute rigid-body rotation. TEPLA is based upon the Gurson flow surface (a potential function used in conjunction with the associated flow law). The original TEPLA equation set has been extended to include anisotropic elastoplasticity and has been recast into a new implicit solution algorithm based upon an eigenvalue scheme to accommodate the anisotropy. This algorithm solves a two-by-two system of nonlinear equations using a Newton–Raphson iteration scheme. Simulations of a shaped-charge jet formation, a Taylor cylinder impact, and an explosively loaded hemishell were selected to demonstrate the utility of this modeling capability. The predicted deformation topology, plastic strain, and porosity distributions are shown for the three simulations.
Transmission Spectra as Diagnostics of Extrasolar Giant Planet Atmospheres

Atmospheres of transiting extrasolar giant planets (EGPs) such as HD 209458b must impose features on the spectra of their parent stars during transits; these features contain information about the physical conditions and chemical composition of the atmospheres. The most convenient observational index showing these features is the "spectrum ratio" (λ), defined as the wavelength-dependent ratio of spectra taken in and out of transit. The principal source of structure in is the variation with wavelength of the height at which the EGP atmosphere first becomes opaque to tangential rays—one may think of the planet as having different radii, and hence different transit depths, at each wavelength. The characteristic depth of absorption lines in scales with the atmospheric scale height and with the logarithm of the opacity ratio between continuum and strong lines. For close-in EGPs, line depths of 10-3 relative to the stellar continuum can occur. The atmospheres of EGPs probably consist mostly of molecular species, including H2, CO, H2O, and CH4, while the illuminating flux is characteristic of a Sun-like star. Thus, the most useful diagnostics are likely to be the near-infrared bands of these molecules, and the visible/near-IR resonance lines of the alkali metals. I describe a model that estimates (λ) for EGPs with prescribed radius, mass, temperature structure, chemical composition, and cloud properties. This model assumes hydrostatic and chemical equilibrium in an atmosphere with chemistry involving only H, C, N, and O. Other elements (He, Na, K, Si) are included as nonreacting minor constituents. Opacity sources include Rayleigh scattering, the strongest lines of Na and K, collision-induced absorption by H2, scattering by cloud particles, and molecular lines of CO, H2O, and CH4. The model simulates Doppler shifts from height-dependent winds and from planetary rotation, and deals in a schematic way with photoionization of Na and K by the stellar UV flux. Using this model, I investigated the diagnostic potential of various spectral features for planets similar to HD 209458b. Clouds are the most important determinants of the depth of features in ; they decrease the strength of all features as they reach higher in the atmosphere. The relative strengths of molecular lines provide diagnostics for the heavy-element abundance, temperature, and the vertical temperature structure, although diagnostics for different physical properties tend to be somewhat degenerate. Planetary rotation with likely periods leaves a clear signature on the line profiles, as do winds with speeds comparable to that of rotation. Successful use of these diagnostics will require spectral observations with signal-to-noise ratio (S/N) of 103 or better and resolving power R = λ/δλ ranging from 103 to 106, depending on the application. Because of these stringent demands, it will be important to evolve analysis methods that combine information from many lines into a few definitive diagnostic indices.
A State-Constrained Approach to Vehicle-Follower Control for Short Headway Automated Transit Systems

Studies vehicle follower control in an automated transit system. In specific, presents a nonlinear feedback controller designed to operate at short time headways with kinematic constraint on vehicle operation.
Quiver polynomials in iterated residue form

Degeneracy loci polynomials for quiver representations generalize several important polynomials in algebraic combinatorics. In this paper we give a nonconventional generating sequence description of these polynomials when the quiver is of Dynkin type.
Exploring the Term of the Auditor‐Client Relationship and the Quality of Earnings: A Case for Mandatory Auditor Rotation?

In this study, we document evidence on the relation between auditor tenure and earnings quality using the dispersion and sign of both absolute Jones‐model abnormal accruals and absolute current acc...
sSCADA: securing SCADA infrastructure communications

Distributed control systems (DCS) and supervisory control and data acquisition (SCADA) systems were developed to reduce labour costs, and to allow system-wide monitoring and remote control from a central location. Control systems are widely used in critical infrastructures such as electric grid, natural gas, water and wastewater industries. While control systems can be vulnerable to a variety of types of cyber attacks that could have devastating consequences, little research has been done to secure the control systems. American Gas Association (AGA), IEC TC57 WG15, IEEE, NIST and National SCADA Test Bed Program have been actively designing cryptographic standard to protect SCADA systems. American Gas Association (AGA) had originally been designing cryptographic standard to protect SCADA communication links and finished the report AGA 12 part 1. The AGA 12 part 2 has been transferred to IEEE P1711. This paper presents an attack on the protocols in the first draft of AGA standard (Wright et al., 2004). This attack shows that the security mechanisms in the first version of the AGA standard protocol could be easily defeated. We then propose a suite of security protocols optimised for SCADA/DCS systems which include: point-to-point secure channels, authenticated broadcast channels, authenticated emergency channels, and revised authenticated emergency channels. These protocols are designed to address the specific challenges that SCADA systems have.
LEAP+: Efficient security mechanisms for large-scale distributed sensor networks

We describe LEAPp (Localized Encryption and Authentication Protocol), a key management protocol for sensor networks that is designed to support in-network processing, while at the same time restricting the security impact of a node compromise to the immediate network neighborhood of the compromised node. The design of the protocol is motivated by the observation that different types of messages exchanged between sensor nodes have different security requirements, and that a single keying mechanism is not suitable for meeting these different security requirements. LEAPp supports the establishment of four types of keys for each sensor node: an individual key shared with the base station, a pairwise key shared with another sensor node, a cluster key shared with multiple neighboring nodes, and a global key shared by all the nodes in the network. LEAPp also supports (weak) local source authentication without precluding in-network processing. Our performance analysis shows that LEAPp is very efficient in terms of computational, communication, and storage costs. We analyze the security of LEAPp under various attack models and show that LEAPp is very effective in defending against many sophisticated attacks, such as HELLO flood attacks, node cloning attacks, and wormhole attacks. A prototype implementation of LEAPp on a sensor network testbed is also described.
Classes of 3-Regular Graphs That Are (7, 2)-Edge-Choosable

A graph is $(7,2)$-edge-choosable if, for every assignment of lists of size $7$ to the edges, it is possible to choose $2$ colors for each edge from its list so that no color is chosen for two incident edges. We show that every $3$-edge-colorable graph is $(7,2)$-edge-choosable and also that many non-$3$-edge-colorable $3$-regular graphs are $(7,2)$-edge-choosable.
Metallization at Microindentations

It is shown that quite generally there is a correlation between insulator-metal transition pressures and indentation hardness numbers for covalent crystals. They are numerically equal for the Group IV elements. Three elements plus five III-V compounds acquire the β-Sn structure upon metallizing. Bondbending, rather than bond-shortening, appears to lead to their transformations. A simple version of the theory of covalent bonds gives the critical transformation bond-angle correctly.
Non-Coherent Amplify-and-Forward Generalized Likelihood Ratio Test Receiver

This paper proposes a simple non-coherent amplify-and-forward receiver for the relay channel and evaluates its diversity performance for Rayleigh fading channels. We use the generalized likelihood ratio test to obtain the decision rule in closed form, independent of the fading distribution. The receiver is developed for M-ary orthogonal signals and multiple relays. The only side information required at the destination is the average noise energy at the receiver; no statistical knowledge of the channel gains is needed. We develop closed-form upper and lower bounds on the probability of error of this receiver for the case of binary signaling with a single relay and show that this receiver achieves near full diversity, with the probability of error decreasing with increasing signal-to-noise ratio (SNR) as log2(SNR)/ SNR2 for large SNR. Additional results obtained by simulation demonstrate increasing diversity gain with additional relays.
Modeling disjunctive constraints with a logarithmic number of binary variables and constraints

Many combinatorial constraints over continuous variables such as SOS1 and SOS2 constraints can be interpreted as disjunctive constraints that restrict the variables to lie in the union of a finite number of specially structured polyhedra. Known mixed integer binary formulations for these constraints have a number of binary variables and extra constraints linear in the number of polyhedra. We give sufficient conditions for constructing formulations for these constraints with a number of binary variables and extra constraints logarithmic in the number of polyhedra. Using these conditions we introduce mixed integer binary formulations for SOS1 and SOS2 constraints that have a number of binary variables and extra constraints logarithmic in the number of continuous variables. We also introduce the first mixed integer binary formulations for piecewise linear functions of one and two variables that use a number of binary variables and extra constraints logarithmic in the number of linear pieces of the functions. We prove that the new formulations for piecewise linear functions have favorable tightness properties and present computational results showing that they can significantly outperform other mixed integer binary formulations.
Empirical uncertainty estimators for astrometry from digital databases

In order to understand the positional uncertainties of arbitrary objects in several of the current major databases containing astrometric information, a sample of extragalactic radio sources with precise positions in the International Celestial Reference Frame is compared with the available positions of their optical counterparts. The discrepancies between the radio and various optical positions are used to derive empirical uncertainty estimators for the USNO-A2.0 and USNO-A1.0 catalogs, the Guide Star Selection System images, and the first and second Digitized Sky Surveys. In addition, an estimate of the uncertainty when the USNO-A2.0 catalog is transferred to different image data is provided. These optical astrometric frame uncertainties can in some cases be the dominant error term when cross-identifying sources at different wavelengths.