cssi/SciSciGPT-SciSciNet huggingface dataset:
Fault characterization of a multilayered perceptron network

The results of a set of simulation experiments conducted to quantify the effects of faults in a classification network implemented as a three-layered perceptron model are reported. The percentage of vectors misclassified by the classification network, the time taken for the network to stabilize, and the output values are measured. The results show that both transient and permanent faults have a significant impact on the performance of the network. Transient faults are also found to cause the network to be increasingly unstable as the duration of a transient is increased. The average percentage of the vectors misclassified is about 25%; after relearning, this is reduced to 10%. The impact of link faults is relatively insignificant in comparison with node faults (1% versus 19% misclassified after relearning). A study of the impact of hardware redundancy shows a linear increase in misclassifications with increasing hardware size. >
Sustainability in the Curriculum and Teaching of Economics: Transforming Introductory Macroeconomics

Present models of economic growth primarily focus on the role of expenditures as captured in the commonly cited economic indicator, gross domestic product (GDP), where GDP is defined as the sum of final goods and services sold within a country’s natural borders. Noting that a country’s expenditures are referred to as “aggregate expenditures” and that the majority of spending is specific to consumption or consumer spending, especially in the United States where this spending category is nearly two-thirds of annual GDP (other expenditure categories for GDP include investment spending, government spending and foreign spending as proxied by net exports), there exists a significant relationship between consumer expenditures and macroeconomic growth, justifying the standard acceptance of consumption-based expenditures as being a significant driver of economic expansion. Given the consumption and growth relationship, consumption values and behaviors have a significant impact on economic outcomes as well as other parameters including the environment and social and economic equity, where the latter are defined as relating to disparities between groups within a country, as well as across countries. Following a discussion of the impact of consumer-led growth on sustainability parameters: the environment, economic and social equity, this paper provides an explicit linkage between the measure of economic progress in universal use, GDP, and the degradation to common global resources, connecting the endogeneity present between the modeling of economic growth and the values and behaviors that support the outcome of the very same growth. A discussion of the present teaching methods specific to introductory macroeconomics provides the foundation for an innovative, replicable, and grant-funded case study for introducing sustainability. The curriculum variants discussed are not in widespread use and at present, there are no standard textbooks for the instruction of Principles of Macroeconomics that explicitly include sustainability and provide sustainability-based economic parameters for alternative evaluation to standard economic growth as presently and singularly enumerated in GDP. The value-augmenting outcome of the sustainability inclusive curriculum case study is captured in a qualitative assessment of student reaction and absorption of sustainability as a value and behavior catalyst and provided in summary form.
TEI Analytics: converting documents into a TEI format for cross-collection text analysis

For the purposes of large-scale analysis of XML/SGML files, converting humanities texts into a common form of markup represents a technical challenge. The MONK (Metadata Offer New Knowledge) Project has developed both a common format, TEI Analytics (a TEI subset designed to facilitate interoperability of text archives) and a command-line tool, Abbot, that performs the conversion. Abbot relies upon a new technique, schema harvesting, developed by the author to convert text documents into TEI-A. This article has two aims: first, to describe the TEI-A format itself and, second, to outline the methods used to convert files. More generally, it is hoped that the techniques described will lead to greater interoperability of text documents for text analysis in a wider context.
Dithiolopyrrolones: biosynthesis, synthesis, and activity of a unique class of disulfide-containing antibiotics.

Covering: up to 2014 Dithiolopyrrolone (DTP) group antibiotics were first isolated in the early half of the 20th century, but only recently has research been reawakened by insights gained from the synthesis and biosynthesis of this structurally intriguing class of molecules. DTPs are characterized by an electronically unique bicyclic structure, which contains a compact disulfide bridge between two ene-thiols. Points of diversity within the compound class occur outside of the bicyclic core, at the two amide nitrogens. Such modifications distinguish three of the most well studied members of the class, holomycin, thiolutin, and aureothricin; the DTP core has also more recently been identified in the marine antibiotic thiomarinol, in which it is linked to a marinolic acid moiety, analog of the FDA-approved topical antibiotic Bactroban® (GlaxoSmithKline). Dithiolopyrrolones exhibit relatively broad-spectrum antibiotic activity against many Gram-positive and Gram-negative bacteria, as well as strains of Mycobacterium tuberculosis. Additionally, they have been shown to exhibit potent and selective anti-cancer activity. Despite this promising profile, there is still much unknown about the mechanisms of action for DTPs. Early reports suggested that they inhibit yeast growth at the level of transcription and that this effect is largely responsible for their distinctive microbial static properties; a similar mechanism is supported in bacteria. Elucidation of biosynthetic pathways for holomycin in Streptomyces clavuligerus and Yersinia ruckeri and thiomarinol in Alteromonas rava sp. nov. SANK 73390, have contributed evidence suggesting that multiple mechanisms may be operative in the activity of these compounds. This review will comprehensively cover the history and development of dithiolopyrrolones with particular emphasis on the biosynthesis, synthesis, biological activity and mechanism of action.
Turbulence Measurements in a Centrifugal Pump With a Synchronously Orbiting Impeller

Turbulence profiles were measured in a centrifugal pump with an impeller with backswept blades using a two-directional laser velocimeter. Data presented include radial, tangential, and cross product Reynolds stresses. Blade-to-blade profiles were measured at four circumferential positions and four radii within and one radius outside the four-bladed impeller. The pump was tested in two configurations : with the impeller running centered within the volute, and with the impeller orbiting with a synchronous motion (e/r 2 =0.016). Flow rates ranged from 40 to 106 percent of the design flow rate
Technology as a complex adaptive system: evidence from patent data

This paper develops a theory of invention by drawing on complex adaptive systems theory. We see invention as a process of recombinant search over technology landscapes. This framing suggests that inventors might face a ‘complexity catastrophe’ when they attempt to combine highly interdependent technologies. Our empirical analysis of patent citation rates supports this expectation. Our results also suggest, however, that the process of invention differs in important ways from biological evolution. We discuss the implications of these findings for research on technological evolution, industrial change, and technology strategy. © 2001 Elsevier Science B.V. All rights reserved.
Design calculations and measurements of a dipole magnet with Permendur pole pieces

A redesign of the SLC (Stanford Linear Collider) south linac-to-ring beam line required that the width of a good field of three of the bending magnets be increased while utilizing the same yokes and coils. Further requirements were that the resulting magnets should have the same strength at two different operating currents as the original magnets. The idea of replacing the steel poles with pole pieces of the high permeability material Permendur was investigated. Design calculations were done using TOSCA and POISSON. An existing prototype magnet was modified with Permendur poles, and magnetic measurements were done. The new magnets were completed, and measurements agreed well with the calculations. The final magnets were within 0.1% of their required strength at 1.21 GeV and had good field regions of +or-32 mm in x at 1.153 GeV and +or-30 mm at 1.21 GeV. >
The Implicit Costs of Trade Credit Borrowing by Large Firms

We examine a novel, but economically important, characterization of trade credit relationships in which large investment-grade buyers borrow from their smaller suppliers. Using a matched sample of large retail buyers and their much smaller suppliers, we find that slower payment terms by large retailers are associated with lower investment at the supplier level. The effects are sharpest during periods of tight bank credit and for firms which we might otherwise characterize as financially constrained. The opportunity cost of extending credit to large buyers appears to be positive and sharply increasing in the financial frictions facing a firm.
Mind the gap: supersymmetry breaking in scaling, microstate geometries

We use a multi-species supertube solution to construct an example of a scaling microstate geometry for non-BPS black rings in five dimensions. We obtain the asymptotic charges of the microstate geometry and show how the solution is related to the corresponding non-BPS black ring. The supersymmetry is broken in a very controlled manner using holonomy and this enables a close comparison with a scaling, BPS microstate geometry. Requiring that there are no closed time-like curves near the supertubes places additional restrictions on the moduli space of physical, non-BPS solutions when compared to their BPS analogs. For large holonomy the scaling non-BPS solution always has closed time-like curves while for smaller holonomy there is a “gap” in the non-BPS moduli space relative to the BPS counterpart.
Market size, structure, and access: Trade with capacity constraints

Abstract This paper develops a model of international trade where firms are heterogeneous across capacity and productivity. A binding capacity constraint induces firms to raise prices in order to take advantage of access to new markets. This generates markets with a flexible competitive structure giving rise to instances where trade and trade liberalization negatively impact welfare. Its key predictions can be identified by observing the presence of small yet highly productive firms and substitution by firms across markets as accessibility evolves. Using Thai firm-level data I establish the prevalence of these anomalous firms and demonstrate they face capacity constraints.
Fast cleavage and deprotection of oligonucleotides

Abstract We have developed methylamine/ammonia as a fast cleavage and deprotection reagent which effects complete cleavage of oligonucleotides from the solid support in 5 min at room temperature and complete deprotection in 5 min at 65°C. The problem of transamination side product formation, faced with the commonly used dCbz (10.0% side product) upon treatment with methylamine/ammonia, has been successfully solved by the use of dCac (0.0% side product). DMT dCac phosphoramidite --methylamine/ammonia system furnished oligonucleotides in equal or superior quality as compared to the other systems.
The Structural Basis of G‐Protein‐Coupled Receptor Signaling (Nobel Lecture)

Complex organisms require a sophisticated communication network to maintain homeostasis. Cells from different parts of our bodies communicate with each other using chemical messengers in the form of hormones and neurotransmitters. Cells process information encoded in these chemical messages using G-protein-coupled receptors (GPCRs) located in the plasma membrane. GPCRs also mediate communication with the outside world. The senses of sight, smell and taste are mediated by GPCRs. GPCRs are nature's most versatile chemical sensors. There are over 800 GPCRs in the human genome and they respond to a broad spectrum of chemical entities ranging from photons, protons and calcium ions, small organic molecules (including odorants and neurotransmitters), to peptides and glycoproteins. The classical role of a GPCR is to detect the presence of an extracellular agonist, transmit the information across the plasma membrane, and activate a cytoplasmic heterotrimeric G protein, leading to modulation of downstream effector proteins. Taking the human β2 adrenergic receptor (β2AR) as an example, binding of adrenaline leads to activation of Gαs, stimulation of adenylyl cyclase, cAMP accumulation, PKA activation, and phosphorylation of proteins involved in cell metabolism (Figure 1). However, a wealth of research has now demonstrated that many GPCRs have more complex signaling repertoires. For example, the β2AR couples to both Gαs and Gαi in cardiac myocytes,[1] and can also signal through MAP kinase pathways in a G-protein-independent manner via arrestin.[2, 3] Similarly, the process of GPCR desensitization involves multiple pathways, including receptor phosphorylation events, arrestin-mediated internalization into endosomes, receptor recycling, and lysosomal degradation. These activities are further complicated by the possibility of GPCR oligomerization,[4] and the localization of receptors to specific membrane compartments having different complements of signaling proteins and different lipid bilayer compositions. Such multifaceted functional behavior has been observed for many different GPCRs. Open in a separate window Figure 1 The complex signaling and regulatory behavior of the β2AR. The inset illustrates the concept of ligand efficacy. PKA=protein kinase A, PKC=protein kinase C, PDE=phosphodiesterase, cAMP=cyclic adenosin monophosphate, Gs=stimulative regulative G protein, Gi=inhibitory regulative G protein, GRK=G-protein-coupled receptor kinase, ERK=extracellular signal-regulated kinase.
Integrated interface for advanced teleoperation

A smart operator interface that simplifies update and control of the automatic features of advanced teleoperators and reduces operator workload is described. The robot joystick has the double function of moving the manipulator and acting as a point-and-click device on a computer screen. The interface can be equipped with knowledge of the teleoperated task and can provide automatic parameter update. A neural network model for peg-in-hole task real-time segmentation is presented as an example of this feature. >
Polynomial regression on riemannian manifolds

In this paper we develop the theory of parametric polynomial regression in Riemannian manifolds. The theory enables parametric analysis in a wide range of applications, including rigid and non-rigid kinematics as well as shape change of organs due to growth and aging. We show application of Riemannian polynomial regression to shape analysis in Kendall shape space. Results are presented, showing the power of polynomial regression on the classic rat skull growth data of Bookstein and the analysis of the shape changes associated with aging of the corpus callosum from the OASIS Alzheimer's study.
Using previous models to bias structural learning in the hierarchical boa

Estimation of distribution algorithms (EDAs) are stochastic optimization techniques that explore the space of potential solutions by building and sampling explicit probabilistic models of promising candidate solutions. While the primary goal of applying EDAs is to discover the global optimum or at least its accurate approximation, besides this, any EDA provides us with a sequence of probabilistic models, which in most cases hold a great deal of information about the problem. Although using problem-specific knowledge has been shown to significantly improve performance of EDAs and other evolutionary algorithms, this readily available source of problem-specific information has been practically ignored by the EDA community. This paper takes the first step toward the use of probabilistic models obtained by EDAs to speed up the solution of similar problems in the future. More specifically, we propose two approaches to biasing model building in the hierarchical Bayesian optimization algorithm (hBOA) based on knowledge automatically learned from previous hBOA runs on similar problems. We show that the proposed methods lead to substantial speedups and argue that the methods should work well in other applications that require solving a large number of problems with similar structure.
Quantum algorithms using the curvelet transform

The curvelet transform is a directional wavelet transform over Rn, which is used to analyze functions that have singularities along smooth surfaces (Candes and Donoho, 2002). I demonstrate how this can lead to new quantum algorithms. I give an efficient implementation of a quantum curvelet transform, together with two applications: a single-shot measurement procedure for approximately finding the center of a ball in Rn, given a quantum-sample over the ball; and, a quantum algorithm for finding the center of a radial function over Rn, given oracle access to the function. I conjecture that these algorithms succeed with constant probability, using one quantum-sample and O(1) oracle queries, respectively, independent of the dimension n -- this can be interpreted as a quantum speed-up. To support this conjecture, I prove rigorous bounds on the distribution of probability mass for the continuous curvelet transform. This shows that the above algorithms work in an idealized "continuous" model.
Multicomponent dynamical systems: SRB measures and phase transitions

We discuss a notion of phase transitions in multicomponent systems and clarify relations between deterministic chaotic and stochastic models of this type of system. Connections between various definitions of SBR measures are considered as well.
Stochastic approximation algorithms for linear discrete-time system identification

The parameter identification problem in the theory of adaptive control systems is considered from the point of view of stochastic approximation. A generalized algorithm for on-line identification of a stochastic linear discrete-time system using noisy input and output measurements is presented and shown to converge in the mean-square sense. The algorithm requires knowledge of the noise variances involved. It is shown that this requirement is a disadvantage associated with on-line identification schemes based on minimum mean-square-error criteria. The paper also presents two off-line identification schemes which utilize measurements obtained from repeated runs of the system's transient response and do not require explicit knowledge of the noise variances. These algorithms converge with probability one to the true parameter values.
The Slippery Slope of Concession

We show that with common knowledge and a common rate of time preference, the potential loser can always avoid wasteful conflict through a time-consistent series of small concessions. We examine how the failure of each of these assumptions may explain why conflicts arise. We also debate which actions may be helpful in such unfortunate circumstances.
Lectures on supersymmetric gauge theories and electric-magnetic duality

We review some of the recent work on the dynamics of four dimensional, supersymmetric gauge theories. The kinematics are largely determined by holomorphy and the dynamics are governed by duality. The results shed light on the phases of gauge theories. Some results and interpretations which have not been published before are also included.
A Fast, Semi-automatic Brain Structure Segmentation Algorithm for Magnetic Resonance Imaging

Medical image segmentation has become an essential technique in clinical and research-oriented applications. Because manual segmentation methods are tedious, and fully automatic segmentation lacks the flexibility of human intervention or correction, semi-automatic methods have become the preferred type of medical image segmentation. We present a hybrid, semi-automatic segmentation method in 3D that integrates both region-based and boundary-based procedures. Our method differs from previous hybrid methods in that we perform region-based and boundary-based approaches separately, which allows for more efficient segmentation. A region-based technique is used to generate an initial seed contour that roughly represents the boundary of a target brain structure, alleviating the local minima problem in the subsequent model deformation phase. The contour is deformed under a unique force equation independent of image edges. Experiments on MRI data show that this method can achieve high accuracy and efficiency primarily due to the unique seed initialization technique.
What is the Shape of Real Exchange Rate Nonlinearity

Evidence that real exchange rate dynamics can be described using models which exhibit nonlinear mean reversion has been mounting over the past decade. This article attempts to better understand the shape of real exchange rate nonlinearity through the use of the Smooth Transition Autoregressive (STAR) model and the newly proposed skewed generalized error transition function. The advantage of this transition function it that it nests popularly used transition functions through simple parameter constraints. This allows the use of nested model selection tests. It is shown that more flexible transition functions are preferred in many cases over the commonly used exponential transition function. The results suggest that most of the real exchange rates studied in this article are better described by discrete threshold models rather than STAR models.
Making the common case the only case with anticipatory memory allocation

We present anticipatory memory allocation (AMA), a new method to build kernel code that is robust to memory-allocation failures. AMA avoids the usual difficulties in handling allocation failures through a novel combination of static and dynamic techniques. Specifically, a developer, with assistance from AMA static analysis tools, determines how much memory a particular call into a kernel subsystem will need, and then preallocates said amount immediately upon entry to the kernel; subsequent allocation requests are serviced from the preallocated pool and thus guaranteed never to fail. We describe the static and runtime components of AMA, and then present a thorough evaluation of Linux ext2-mfr, a case study in which we transform the Linux ext2 file system into a memory-failure robust version of itself. Experiments reveal that ext2-mfr avoids memory-allocation failures successfully while incurring little space or time overhead.
Resource Allocation for OFDMA Cognitive Radios Under Channel Uncertainty

A resource allocation problem for a cognitive radio base station (CR-BS) communicating with multiple CR mobile stations (MSs) is considered in the downlink, which relies on orthogonal frequency-division multiple access (OFDMA). To protect the incumbent primary user (PU) system operating over the same frequency band, the interference inflicted to the PU receiver must be regulated. Since the channel gain estimates from the CR-BS to the PU receiver are typically uncertain in practice, a robust interference power constraint is advocated. Although the latter translates to a second-order cone constraint, the overall optimization problem for joint transmit-power and subcarrier allocation is non-convex, and coupled over all subcarriers in general. To circumvent the resulting computational hurdle, a tight polyhedral approximation of the second-order cone is employed. Practical finite-alphabet constellations are adopted and total weighted achievable rate is maximized. It is shown that a near-optimal solution can be obtained based on the Lagrangian dual.
Almost analytic models of ultramagnetized neutron star envelopes

Recent ROSAT measurements show that the x-ray emission from isolated neutron stars is modulated at the stellar rotation period. To interpret these measurements, one needs precise calculations of the heat transfer through the thin insulating envelopes of neutron stars. We present nearly analytic models of the thermal structure of the envelopes of ultramagnetized neutron stars. Specifically, we examine the limit in which only the ground Landau level is filled. We use the models to estimate the amplitude of modulation expected from non-uniformities in the surface temperatures of strongly magnetized neutron stars. In addition, we estimate cooling rates for stars with fields B � 10 15 10 16 G which are relevant to models that invoke “magnetars” to account for soft -ray emission from some repeating sources.
Prelude to compressed baryonic matter

Why study compressed baryonic matter, or more generally strongly interacting matter at high densities and temperatures? Most obviously, because it’s an important piece of Nature. The whole universe, in the early moments of the big bang, was filled with the stuff. Today, highly compressed baryonic matter occurs in neutron stars and during crucial moments in the development of supernovae. Also, working to understand compressed baryonic matter gives us new perspectives on ordinary baryonic matter, i.e. the matter in atomic nuclei. But perhaps the best answer is a variation on the one George Mallory gave, when asked why he sought to scale Mount Everest: Because, as a prominent feature in the landscape of physics, it’s there. Compressed baryonic matter is a material we can produce in novel, challenging experiments that probe new extremes of temperature and density. On the theoretical side, it is a mathematically well-defined domain with a wealth of novel, challenging problems, as well as wide-ranging connections. Its challenges have already inspired a lot of very clever work, and revealed some wonderful surprises, as documented in this volume.
Dynamic Modeling, Stability, and Energy Efficiency of a Quadrupedal Walking Machine

In the past, the dynamics of walking machines was studied based on very simple or simplified leg structures. A more complete dynamic model is essential for the further development of a practical walking machine. In this paper, the dynamic model of a realistic quadrupedal walking machine is derived for simulation and real-time control purposes. The walker has four cylindrical pantograph legs, and the whole system consists of twenty-nine links. The walking gait is wave gait with at least three feet on the ground at any time. Significant efforts have been made to improve the computational efficiency of the inverse dynamics, and the required CPU time is less than 10 ms on an IBM 3090. The derived dynamic model is then applied to study two practical issues of walking: dynamic stability and mechanical efficiency of different legs and gaits. Simulation results show clear advantages of one leg type over another, and of some walking strategies in terms of adjusting velocities, strokes, and duty factors for greater efficiency. © 2001 John Wiley & Sons, Inc.
The CERF computer system

Multiprocessor systems are becoming increasingly popular because of the increased throughput possible and the possibility of system availability despite the failure of some of the processing units. This paper describes an innovative concept in multiprocessor system design, and suggests some of the research areas which have not yet been resolved but which can be studied on this system. The system architecture is patterned after Control Data Corporation's peripheral processor "barrel" except that it possesses much more powerful functional capabilities. In addition, high speed minicomputers were used to handle all of the system I/O requirements. Research areas for which this system is particularly appropriate include computer architecture-operating systems tradeoffs and multiprocessor operating systems design and implementation. The hardware system is entirely microprogrammable, allowing for increased flexibility in evaluating various research strategies.
Event ordering in pervasive sensor networks

In a pervasive sensor system, application entities may use the available infrastructure resources such as sensing devices, actuators, wireless modules and gateways to accomplish various tasks. For example, a group of humans/robots may use the infrastructure to track the current location of the group members. Many such tasks require a service which keeps track of the order of occurrence of events in the application. Existing algorithms for this problem have been designed for traditional distributed systems using the layering paradigm where the algorithm is able to observe and intercept application messages. Pervasive applications, however, may not be structured as strictly layered systems. In this paper, we study the problem of event ordering in pervasive systems, and propose algorithms for detecting event ordering. Our first algorithm treats the entire network as a single graph, whereas the second algorithm operates in a hierarchical manner by subdividing the network into smaller groups. We present experimental evaluation of our algorithms using both simulation and deployment on a sensor testbed.
Chromaticities of Lovibond Glasses

This paper reports by means of a series of graphs the chromaticity coordinates of certain Lovibond unit glasses and of pairs of such glasses in combination with an illuminant of color temperature 2842°K (Illuminant A). The chromaticities were computed according to the 1931 I.C.I. standard observer and coordinate system. The points graphically representing the x and y values have been labelled according to the Lovibond numbers and have been connected by lines to form a network. A similar graph is included for a few Lovibond glasses in combination with Illuminant C. The Lovibond glasses are those from the NBS set designated as “BS9940,” and the spectrophotometric data on which the colorimetric computations are based are those published by Gibson and Harris.
The nilpotence conjecture in K -theory of toric varieties

It is shown that all nontrivial elements in higher K-groups of toric varieties are annihilated by iterations of the natural Frobenius type endomorphisms. This is a higher analog of the triviality of vector bundles on affine toric varieties.
A higgs-like dilaton: viability and implications

We re-examine the feasibility of the higgs-like particle discovered at the LHC being a dilaton: the Goldstone boson of spontaneous breaking of scale invariance. We review the expected phenomenological de- viations from the SM higgs and compare with other Goldstone higgs scenarios, with particular emphasis on double higgs production.
The new war correspondents: the rise of civic media curation in urban warfare

In this paper we examine the information sharing practices of people living in cities amid armed conflict. We describe the volume and frequency of microblogging activity on Twitter from four cities afflicted by the Mexican Drug War, showing how citizens use social media to alert one another and to comment on the violence that plagues their communities. We then investigate the emergence of civic media "curators," individuals who act as "war correspondents" by aggregating and disseminating information to large numbers of people on social media. We conclude by outlining the implications of our observations for the design of civic media systems in wartime.
Strategic Trade Policy Under Incomplete Information

This paper examines equilibrium trade policies when firms have better information than governments about the profitability of the industry. Contrary to the intuition that the policymakers' lack of information should reduce their incentives to engage in strategic trade intervention, the analysis suggests that information asymmetries may increase trade policy distortions in equilibrium and ultimately worsen the “prisoner's dilemma” between governments.
Studies toward the synthesis of α-fluorinated phosphonates via tin-mediated cleavage of α-fluoro-α-(pyrimidin-2-ylsulfonyl)alkylphosphonates. Intramolecular cyclization of the α-phosphonyl radicals

Treatment of the alpha carbanions generated from several alpha-(pyrimidin-2-ylsulfonyl)alkylphosphonates with Selectfluor gave high yields of the alpha-fluoro-alpha-(pyrimidin-2-ylsulfonyl)alkylphoshonates, which were desulfonylated [Bu(3)SnH/2,2'-azobisisobutyronitrile (AIBN)/benzene or toluene/Delta] to give alpha-fluoroalkylphosphonates. "Catalytic" tin hydride, generated from tributyltin chloride and excess polymethylhydrosiloxane in the presence of potassium fluoride, also effected removal of the pi-deficient alpha-(pyrimidin-2-ylsulfonyl) group from the phosphonate esters. Substitution of Bu(3)SnD for Bu(3)SnH gave access to alpha-deuterium-labeled phosphonates. Prolonged treatment of alpha-(pyridin-2-ylsulfonyl)alkylphosphonate with excess Bu(3)SnH/AIBN or catalytic tin hydride also effected desulfonylation but in moderate yields. This represents a mild new methodology for removal of the synthetically useful pi-deficient heterocyclic sulfone moiety and an alternative route for the preparation of alpha-fluorinated phosphonates. Desulfonylation is suggested to proceed via attack of tin radical at an oxygen (or sulfur) atom of the sulfonyl group to give a stabilized alpha-phosphonyl radical intermediate. The latter was found to undergo 5-exo-trig ring closure to give the corresponding 2-methylcyclopentylphosphonates. Treatment of diethyl 1-bromohex-6-enylphosphonate with Bu(3)SnH/AIBN produced an analogous mixture of ring-closure products. Treatment of [(2-bromo-5- methoxyphenyl)(fluoro)(pyrimidin-2-ylsulfonyl)]methylphosphonate with Bu(3)SnH resulted in an intramolecular radical [1,5]-ipso substitution reaction and migration of the pyrimidinyl ring to give fluoro[5-methoxy-2-(pyrimidin-2-yl)phenyl]methylphosphonate.
Hierarchical task and motion planning in the now

In this paper we outline an approach to the integration of task planning and motion planning that has the following key properties: It is aggressively hierarchical; it makes choices and commits to them in a top-down fashion in an attempt to limit the length of plans that need to be constructed, and thereby exponentially decrease the amount of search required. It operates on detailed, continuous geometric representations and does not require a-priori discretization of the state or action spaces.
Polymorphic self-* agents for stigmergic fault mitigation in large-scale real-time embedded systems

Organization and coordination of agents within large-scale, complex, distributed environments is one of the primary challenges in the field of multi-agent systems. A lot of interest has surfaced recently around self-* (self-organizing, self-managing, self-optimizing, self-protecting) agents. This paper presents polymorphic self-* agents that evolve a core set of roles and behavior based on environmental cues. The agents adapt these roles based on the changing demands of the environment, and are directly implementable in computer systems applications. The design combines strategies from game theory, stigmergy, and other biologically inspired models to address fault mitigation in large-scale, real-time, distributed systems. The agents are embedded within the individual digital signal processors of BTeV, a High Energy Physics experiment consisting of 2500 such processors. Results obtained using a SWARM simulation of the BTeV environment demonstrate the polymorphic character of the agents, and show how this design exceeds performance and reliability metrics obtained from comparable centralized, and even traditional decentralized approaches.
Holistic operations in large-scale sensor network systems: a probabilistic peer-to-peer approach

Smart sensor nodes integrate multiple sensors (e.g., temperature, humidity, accelerometers), processing capability (microprocessor connected to the sensors using I2C technology), wireless communications, and a battery power source. A sensor node could be as small as a few millimeters. See references [32.11], [32.12].
On the convergence of the Born series in optical tomography with diffuse light

We provide a simple sufficient condition for the convergence of the Born series in the forward problem of optical diffusion tomography. The Born series considered in this paper is an expansion of Green's function or the T-matrix for the diffusion equation in an inhomogeneous medium in a functional power series in δα(r) or δD(r) which are the deviations of the absorption and diffusion coefficients of the medium from their respective background values α0 and D0. The condition we obtain depends only on upper bounds for the inhomogeneity functions but not on their detailed form or spatial extent.
Observations of Rapid Disk-Jet Interaction in GRS 1915+105

We present evidence that ~ 30 minute episodes of jet formation in GRS 1915+105 may sometimes be a superposition of smaller, faster phenomena. Based on observations in 2002 July using the Rossi X-ray Timing Explorer and the Palomar 5 meter telescope, we show that GRS 1915+105 sometimes produces ~ 30 minute infrared flares that can entirely be explained as a combination of small (~ 150 second) flares, one for each oscillation in the accompanying X-ray light curve. We discuss the differences between these observations and similar ones in 1997 August and conclude that an X-ray "trigger spike" seen during each cycle in 1997 is a key ingredient for large ejections to occur on ~ 30 minute timescales in this source.
Seismic Search for Strange Quark Matter

We briefly review the status of strange quark matter and the capabilities of seismic networks for detecting nuggets of strange quark matter that pass through the Earth if an appreciable fraction of galactic halo dark matter is in the form of ton-sized nuggets. We describe progress to date in analyzing 13 years of seismic data and we note the possibility that new networks under development for verifying compliance with the recently negotiated Comprehensive Test Ban Treaty might be capable of contributing to detection of such nuggets.
Output Supply and Input Demand System of Commercial and Backyard Poultry Producers in Indonesia

Indonesia's domestic broiler production has grown rapidly, in part because of a ban on imports of poultry parts and strict inspection and meat certification requirements. Whether Indonesia will continue to protect the domestic broiler sector and import feed grains and other inputs or whether it will directly import meat products is a relevant question to many stakeholders. This study uses a normalized quadratic function to estimate the output supply of commercial and backyard broiler producers in Indonesia and the input demand for three major inputs: day-old chicks, feed, and labor. Data come from three datasets: a 1996 household survey and 1996 and 2000 surveys of commercial producers. For the most recent dataset, the own-price elasticity in both the output supply and feed input demand equations were found to be significant. The signs of the elasticities were theoretically consistent, with a positive supply and negative demand elasticity. The magnitudes of the elasticities were smaller than expected (the supply elasticity was 0.285). The inelastic supply explains the high border protection imposed by Indonesia, which in turn implies that any income-driven expansion in the quantity of broiler product demanded would be quickly constrained by rising prices. Consequently, supply from imports would become attractive and would dampen any incentive for growth in the domestic sector. This result cast doubt on the long-term sustainability of Indonesia's import substitution policy regime.
Tumor Cell - Substrate Stabilization Mediated by Integrins

Metastasis formation is dependent on the arrest and stabilization of adhesive interactions to prevent detachment from secondary sites. Primary receptor-ligand interactions are not sufficient to maintain prolonged adhesive contacts without secondary events that lead to stabilization. Tumor cell arrest and stabilization were studied under physiologically relevant shear conditions. We used a parallel-plate flow chamber with surfaces coated with human plasma fibronectin or vitronectin. Our previous work suggested that stabilization of cells to immobilized proteins is in part attributed to transglutaminase covalently cross-linking cytoskeletal-integrin-fibronectin multiprotein complexes via lysine-glutamine linkages. To study the role of integrins in mediating arrest and initiating stabilization we used a human melanoma line (70w) and polyclonal antibodies that inhibit the function of the fibronectin (α 5 β 1 ) and vitronectin (α v β 3 /β 5 ) integrin receptors. To confirm the role of integrins in initiating stabilization we used CHO (Chinese hamster ovary) cells selected for low levels of α 5 β 1 integrin expression and integrin transfected CHO cells selected for α 5 β l overexpression. The level of fibronectin receptor surface expression was inversely related to the adhesion stabilization lag time. These studies confirmed that integrins are essential for mediating arrest and initiating stabilization. They also confirm that secondary events are necessary for complete stabilization to occur. Finally, it is important to note that the arrest and stabilization methods we have developed are capable of detecting biologic effects at far greater sensitivity than static adhesion assays. Some examples of pharmacologic agents or biomaterials effects that can be detected using stabilization assays include: 1) very low drug doses, 2) very low levels of peptide, carbohydrate, and antibody inhibitors, 3) slight modification of endogenous protein expression by antisense oligonucleotides or transfected genetic expression constructs.
Lorentz contraction, Bell’s spaceships and rigid body motion in special relativity

The meaning of Lorentz contraction in special relativity and its connection with Bell's spaceships parable is discussed. The motion of Bell's spaceships is then compared with the accelerated motion of a rigid body. We have tried to write this in a simple form that could be used to correct students' misconceptions due to conflicting earlier treatments.
On the accuracy of the hydroperoxide method of determining absolute rate constants for hydrogen atom abstraction by the tert‐butylperoxy radical

Measurements of rates of oxygen absorption and steady-state peroxy radical concentrations for the autoxidation of tetralin in the presence of tert-butyl hydroperoxide have shown that the rate constant for reaction of the tert-butylperoxy radical with tetralin at 60°C is approximately 11.0 M−1s−1. This rate constant is about a factor of 4 larger than the value recently reported by Niki, Okayasu, and Kamiya for this reaction. The present work emphasizes that great care should be taken when the hydroperoxide method is used to estimate cross-propagation rate constants for a substrate as reactive as tetralin at a temperature as high as 60°C.
Investigation of Ancient DNA from Western Siberia and the Sargat Culture

Abstract Mitochondrial DNA from 14 archaeological samples at the Ural State University in Yekaterinburg, Russia, was extracted to test the feasibility of ancient DNA work on their collection. These samples come from a number of sites that fall into two groupings. Seven samples are from three sites, dating to the 8th–12th century AD, that belong to a northern group of what are thought to be Ugrians, who lived along the Ural Mountains in northwestern Siberia. The remaining seven samples are from two sites that belong to a southern group representing the Sargat culture, dating between roughly the 5th century BC and the 5th century AD, from southwestern Siberia near the Ural Mountains and the present-day Kazakhstan border. The samples are derived from several burial types, including kurgan burials. They also represent a number of different skeletal elements and a range of observed preservation. The northern sites repeatedly failed to amplify after multiple extraction and amplification attempts, but the sample...
Quantum gravity on the lattice

I review the lattice approach to quantum gravity, and how it relates to the non-trivial ultraviolet fixed point scenario of the continuum theory. After a brief introduction covering the general problem of ultraviolet divergences in gravity and other non-renormalizable theories, I discuss the general methods and goals of the lattice approach. An underlying theme is the attempt at establishing connections between the continuum renormalization group results, which are mainly based on diagrammatic perturbation theory, and the recent lattice results, which apply to the strong gravity regime and are inherently non-perturbative. A second theme in this review is the ever-present natural correspondence between infrared methods of strongly coupled non-abelian gauge theories on the one hand, and the low energy approach to quantum gravity based on the renormalization group and universality of critical behavior on the other. Towards the end of the review I discuss possible observational consequences of path integral quantum gravity, as derived from the non-trivial ultraviolet fixed point scenario. I argue that the theoretical framework naturally leads to considering a weakly scale-dependent Newton’s constant, with a scaling violation parameter related to the observed scaled cosmological constant (and not, as naively expected, to the Planck length).
Expansion aspect of color transparency on the lattice

Abstract The opportunity to observe color transparency (CT) is determined by how rapidly a small-sized hadronic wave packet expands. Here we use SU(2) lattice gauge theory with Wilson fermions in the quenched approximation to investigate the expansion. The wave packet is modeled by a point hadronic source, often used as an interpolating field in lattice calculations. The procedure is to determine the Euclidean time (t), pion channel, Bethe-Salpeter amplitude Ψ(r,t) and then evaluate b2(t) = ∫ d3rΨ (r,t)r2sin2 θψπ(r). This quantity represents the soft interaction of a small-sized wave packet with a pion. The time dependence of b2(t) is fit as a superposition of three states, which is found sufficient to reproduce a reduced-size wave packet. Using this superposition allows us to make the analytic continuation required to study the wave packet expansion in real time. We find that the matrix elements of the soft interaction b ^ 2 between the excited and ground state decrease rapidly with the energy of the excited state.
Initial conditions for the hypersonic-shock/boundary-layer interaction problem.

Boundary layers interacting with a hypersonic mainstream over hot and cold flat plates are solved numerically using an implicit finite-difference scheme. Attention is given to the details of the initialization procedure needed to allow subcritical boundary-layer development. The exact starting model is investigated and applied over a representative range of wall temperatures. Solutions so obtained display either monotonically increasing or decreasing pressure levels depending on the sign of a single free constant with attention here focused on the former since it leads to a boundary-layer separation.
Solvent-free accelerated organic syntheses using microwaves

A solvent-free approach for organic synthesis is described which involves microwave (MW) exposure of neat reactants (undiluted) either in the presence of a catalyst or catalyzed by the surfaces of inexpensive and recyclable mineral supports such as alumina, silica, clay, or "doped" surfaces, namely, Fe(NO3)3-clay (clayfen), Cu(NO3)2-clay (claycop), NH 2 OH-clay, PhI(OAc) 2 -alumina, NaIO4-silica, MnO 2 -silica, and NaBH 4 -clay. A variety of deprotection, condensation, cyclization, oxidation, and reduction reactions are presented including the efficient one-pot assembly of heterocyclic molecules from in situ generated intermediates such as enamines and α -tosyloxyketones. The application of this solvent-free MW approach to multicomponent reactions is highlighted that can be adapted for high-speed parallel synthesis of the library of dihydropyrimidine-2(1 H)-ones and imidazo (1,2-a)annulated pyridines, pyrazines, and pyrimidines.