cssi/SciSciGPT-SciSciNet huggingface dataset:
Input-to-State Stability of Periodic Orbits of Systems With Impulse Effects via Poincaré Analysis

In this paper, we investigate the relation between robustness of periodic orbits exhibited by systems with impulse effects and robustness of their corresponding Poincare maps. In particular, we prove that input-to-state stability (ISS) of a periodic orbit under external excitation in both continuous and discrete time is equivalent to ISS of the corresponding zero-input fixed point of the associated forced Poincare map. This result extends the classical Poincare analysis for asymptotic stability of periodic solutions to establish orbital ISS of such solutions under external excitation. In our proof, we define the forced Poincare map, and use it to construct ISS estimates for the periodic orbit in terms of ISS estimates of this map under mild assumptions on the input signals. As a consequence of the availability of these estimates, the equivalence between exponential stability (ES) of the fixed point of the zero-input (unforced) Poincare map and the ES of the corresponding orbit is recovered. The results can be applied naturally to study the robustness of periodic orbits of continuous-time systems as well. Although our motivation for extending classical Poincare analysis to address ISS stems from the need to design robust controllers for limit-cycle walking and running robots, the results are applicable to a much broader class of systems that exhibit periodic solutions.
Streamlining effects of extra telomeric repeat on telomeric DNA folding revealed by fluorescence-force spectroscopy.

Abstract A human telomere ends in a single-stranded 3′ tail, composed of repeats of T2AG3. G-quadruplexes (GQs) formed from four consecutive repeats have been shown to possess high-structural and mechanical diversity. In principle, a GQ can form from any four repeats that are not necessarily consecutive. To understand the dynamics of GQs with positional multiplicity, we studied five and six repeats human telomeric sequence using a combination of single molecule FRET and optical tweezers. Our results suggest preferential formation of GQs at the 3′ end both in K+ and Na+ solutions, with minor populations of 5′-GQ or long-loop GQs. A vectorial folding assay which mimics the directional nature of telomere extension showed that the 3′ preference holds even when folding is allowed to begin from the 5′ side. In 100 mM K+, the unassociated T2AG3 segment has a streamlining effect in that one or two mechanically distinct species was observed at a single position instead of six or more observed without an unassociated repeat. We did not observe such streamlining effect in 100 mM Na+. Location of GQ and reduction in conformational diversity in the presence of extra repeats have implications in telomerase inhibition, T-loop formation and telomere end protection.
Methods of Metabolite Identification Using MS/MS Data

Researchers in bioinformatics and medical science fields have been developing various innovative information systems and software tools using emerging technologies. Metabolite profiling is one of t...
Septic Arthritis and the Opioid Epidemic: 1465 Cases of Culture-Positive Native Joint Septic Arthritis From 1990-2018.

Background The clinical spectrum of septic arthritis in the era of the opioid crisis is ill-defined. Methods This is a retrospective chart review of 1465 cases of culture-positive native joint septic arthritis at Boston teaching hospitals between 1990 and 2018. Results Between 1990-2008 and 2009-2018, the proportion of septic arthritis cases involving people who inject drugs (PWID) rose from 10.3% to 20% (P < .0000005). Overall, methicillin-sensitive Staphylococcus aureus (MSSA) caused 41.5% of cases, and methicillin-resistant Staphylococcus aureus (MRSA) caused 17.9%. Gram-negative rods caused only 6.2% of cases. Predictors of MRSA septic arthritis included injection drug use (P < .001), bacteremia (P < .001), health care exposure (P < .001), and advancing age (P = .01). Infections with MSSA were more common in PWID (56.3% vs 38.8%; P < .00001), as were infections with MRSA (24% vs 16.8%; P = .01) and Serratia sp. (4% vs 0.4%; P = .002). Septic arthritis in the setting of injection drug use was significantly more likely to involve the sacroiliac, acromioclavicular, and facet joints; 36.8% of patients had initial synovial fluid cell counts of <50 000 cells/mm3. Conclusions Injection drug use has become the most common risk factor for septic arthritis in our patient population. Septic arthritis in PWID is more often caused by MRSA, MSSA, and Serratia sp., and is more prone to involve the sacroiliac, acromioclavicular, sternoclavicular, and facet joints. Synovial fluid cell counts of <50 000 cells/mm3 are common in culture-positive septic arthritis.
Complexity and Stability

A recurring problem in ecology is the relation between the complexity of an ecosystem and its stability. Most ecologists assumed the two concepts went together, i.e., greater complexity was associated with greater stability. However, May (1973) challenged this assumption and, indeed, showed that for Lotka—Volterra models of ecosystems, the opposite is sometimes true. However, he did not consider compartmental models and used only the number of nonzero flows as an indicator of complexity. For compartmental models, another approach, that we shall use, is possible.
Climate Change and Population Health: Incorporating Stages of Nursing's Political Development.

Abstract Climate change is the greatest public health threat of the 21st century and is associated with environmental degradation and deleterious health consequences. In 2019, the Lancet Commission Report on Health and Climate Change: Ensuring that the Health of a Child Born Today Is Not Defined By a Changing Climate (Watts et al., 2019) examined the critical health issues that children will face in the era of climate change. Greenhouse gas emissions (GGEs) are responsible for an alarming increase in the warming of the planet, shifts in weather patterns, loss of arable land, and exacerbations of acute health issues, chronic health problems, and disaster-related health consequences. The purpose of this paper is to provide an overview of climate change and the associated deleterious health consequences in our climate-changing world. The paper will also examine the stages of political development to advance the 21st century role of the nursing profession in climate and health advocacy and policy.
Simulated Versus Real Life Data in Testing the Efficiency of Scheduling Algorithms

Abstract This paper compares and contrasts the use of simulated versus real data in testing the efficiency of scheduling algorithms. Five hypotheses, formulated to evaluate two important measures of algorithm efficiency, viz., CPU time and the number of iterations, are tested on over one hundred problems drawn from different sources. On the basis of these empirical results, it is shown that: (1) the real problems are easier to solve than the simulated ones; and (2) the Natural Order heuristic is more effective on real problems than simulated ones. Implications of these results for testing the efficiency of algorithms are discussed.
Employment Screening for Paralegals, Office Staff, and Other Nonlawyer Assistants

Paralegals, law clerks. and nonlawyer office assistants assume responsibilities not generally encountered in most workplaces except for perhaps clinical healthcare employees. Nonattorney law firm employees must be professional and discreet when interacting with clients, witnesses, outside counsel, police, judges, and many others.
The Falls of Rome: Crises, Resilience, and Resurgence in Late Antiquity

Over the course of the fourth through seventh centuries, Rome witnessed a succession of five significant political and military crises, including the Sack of Rome, the Vandal occupation, and the demise of the Senate. Historians have traditionally considered these crises as defining events, and thus critical to our understanding of the 'decline and fall of Rome.' In this volume, Michele Renee Salzman offers a fresh interpretation of the tumultuous events that occurred in Rome during Late Antiquity. Focusing on the resilience of successive generations of Roman men and women and their ability to reconstitute their city and society, Salzman demonstrates the central role that senatorial aristocracy played, and the limited influence of the papacy during this period. Her provocative study provides a new explanation for the longevity of Rome and its ability, not merely to survive, but even to thrive over the last three centuries of the Western Roman Empire.
Model neocortical microcircuit supports beta and gamma rhythms

Gamma and beta rhythms in neocortical circuits are thought to be caused by distinct subcircuits involving different type of interneurons. However, it is not clear how these distinct but inter-linked intrinsic circuits interact with afferent drive to engender the two rhythms. We report a biophysical computational model to investigate the hypothesis that tonic and phasic drive might engender beta and gamma oscillations, respectively, in a neocortical circuit.
Roman Architecture in Provence

This book provides a survey of the architecture and urbanism of Provence during the Roman era. Provence, or 'Gallia Narbonensis' as the Romans called it, was one of the earliest Roman colonies in Western Europe. In this book, James C. Anderson, jr. examines the layout and planning of towns in the region, both those founded by the Romans and those redeveloped from native settlements. He provides an in-depth study of the chronology, dating and remains of every type of Roman building for which there is evidence in Provence. The stamp of Roman civilization is apparent today in such cities as Orange, Nimes and Arles, where spectacular remains of bridges, theaters, fora and temples attest to the sophisticated civilization that existed in this area during the imperial period and late antiquity. This book focuses on the remains of buildings that can still be seen, exploring decorative elements and their influence from Rome and local traditions, as well as their functions within the urban environment.
Reanimation Schemes for Partial Facial Palsies

To study partial facial palsies, to understand the mechanism of the deformity, and to design therapeutic schemes to reverse the facial imbalance.
A Far Upstream Region is Required for Expression of the ftsI Gene Coding for Penicillin-Binding Protein 3 of Escherichia coli

The ftsI (pbpB) gene of Escherichia coli codes for penicillin-binding protein 3 (PBP 3), a cytoplasmic membrane protein that functions as DD-transpeptidase for the formation of a septum of the murein sacculus and is the principal lethal target of β-lactam antibiotics. PBP 3 was shown to be essential for cell division by analyzing thermosensitiv ftsI mutants and their revertants (Spratt, 1977). The ftsI gene is located at 2 min on the E. coli genetic map, a little distal to leu, and is among a large cluster of murein biosynthetic genes (mur genes and ddl) and cell division genes (fts genes and envA). The DNA sequence of 28 kilobases (kb) of this region including the whole cluster has been determined (EMBL database, entry name EC2MIN).
Determination of the solvent density profiles across mesopores of silica-C18 bonded phases in contact with acetonitrile/water mixtures: A semi-empirical approach.

The local volume fractions of water, acetonitrile, and C18-bonded chains across the 96Amesopores of 5μm Symmetry particles were determined semi-empirically. The semi-empirical approach was based on previous molecular dynamics studies, which provided relevant mathematical expressions for the density profiles of C18 chains and water molecules, and on minor disturbance experiments, which measured the excess amount of acetonitrile adsorbed in the pores of Symmetry-C18 particles. The pore walls of the Symmetry-C18 material were in thermodynamic equilibrium with a series of binary mixtures of water and acetonitrile. The results show that C18 chains are mostly solvated by acetonitrile molecules, water is excluded from the C18-bonded layer, and acetonitrile concentrates across a 15-25Athick interface region between the C18 layer and the bulk phase. These actual density profiles are expected to have a direct impact on the retention behaviour of charged, polar, and neutral analytes in RPLC. They also provide clues to predict the local mobility of analytes inside the pores and a sound physico-chemical description of the phenomenon of surface diffusion observed in RPLC.
CHAPTER 12 – Raman Scattering

Raman scattering refers to most types of inelastic scattering of electromagnetic radiation, which, in quantized form, consists of photons. Photons entering a medium can lose energy to the sample, which is referred to as Stokes scattering, or gain energy, which is anti-Stokes scattering. Raman scattering in solids is often described in terms of the excitation or de-excitation of quantized elementary excitations, such as optical phonons (vibrational Raman scattering) or magnons (magnetic Raman scattering), and the interaction with single electrons or collective excitations of electrons, plasmons (electronic Raman scattering). In molecules, Raman scattering leads to changes in the population of vibrational and rotational states. Raman scattering has been widely used in the fundamental spectroscopic study of excitations in solids, liquids, and gases and has also been extensively used in materials characterization. Vibrational and rotational Raman scattering have been used for in situ diagnostics during thin film processing.
Velocity Control of Solid Upper Stages Using Attitude Modulation

A closed-loop scheme for controlling the speed of solid rocket propelled spacecraft is described. Using a proportional plus integral control law, this scheme superimposes pitch-yaw attitude oscillations on the nominal guidance commands to control the spacecraft speed during the motor burn. Oscillation frequency is selected based on the permissible lateral acceleration magnitude. Feasibility of this approach is demonstrated using a nonlinear point-mass simulation of a typical spacecraft performing an orbit transfer mission. Acceptable accuracies are found to be achievable even with the use of a simple control logic.
A carboxyl terminal truncation mutant of CD36 is secreted and binds thrombospondin: evidence for a single transmembrane domain

CD36 has been implicated in several intracellular signalling events, including platelet and monocyte activation, and receptor-mediated internalization of bound ligands such as oxidized low-density lipoprotein and apoptotic neutrophils. These processes are presumably mediated by the intracytoplasmic domain(s) of the molecule. By analysis of hydrophobicity plots and by analogy to rat LIMPII, which has a 60% homology to CD36, a two-transmembrane domain model has been proposed. To characterize the structure-function relationships of CD36 involved in transducing the signal, we have defined the number of transmembrane and intracellular domains experimentally using a mutagenesis approach. A truncated CD36 cDNA was constructed that encodes a protein that terminates just proximal to the putative C-terminal transmembrane domain. This mutant was cloned into eukaryotic expression plasmid vectors to generate short-term and stable transfected cells. Our results indicate that the truncated mutant is secreted by the transfectants into the postculture medium, indicating that there is only one transmembrane domain in CD36, which is present at the C- terminal end. The soluble secreted protein from all of these cells is functional as indicated by its binding to thrombospondin.
Chloro(thexyl)borane

[75030-54-5] C6H14BCl (MW 132.43) InChI = 1/C6H14BCl/c1-5(2)6(3,4)7-8/h5,7H,1-4H3 InChIKey = SYRKSQMQOSOIGG-UHFFFAOYAE (hydroboration agent) Alternate Name: chloro(1,1,2-trimethylpropyl)borane.
Efficacy of Antiarrhythmic Drugs in Arrhythmogenic Right Ventricular Cardiomyopathy: A Report From the North American ARVC Registry

Objectives This study sought to examine the efficacy of empiric antiarrhythmic drugs in a rigorously characterized cohort of arrhythmogenic right ventricular cardiomyopathy (ARVC) patients. Background Antiarrhythmic drugs are important in protecting against ventricular arrhythmias in ARVC, but no studies have provided data in a group rigorously screened for the disease. Methods Antiarrhythmic medicines were examined in all subjects with implantable cardioverter-defibrillators (ICDs) enrolled in the North American ARVC Registry. A Cox proportional hazards model was used to account for time on each drug, and a hierarchical analysis was performed for repeated measures within individuals. Results Ninety-five patients were studied, with a mean follow-up of 480 ± 389 days. Fifty-eight (61%) received beta-blockers, and these medicines were not associated with an increased or decreased risk of ventricular arrhythmias. Sotalol was associated with a greater risk of any clinically relevant ventricular arrhythmia as defined by sustained ventricular tachycardia or ICD therapy (hazard ratio [HR]: 2.55, 95% confidence interval [CI]: 1.02 to 6.39, p = 0.045), but this was not statistically significant after adjusting for potential confounders. An increased risk of any ICD shock and first clinically relevant ventricular arrhythmia while on sotalol remained significant after multivariable adjustment. Those on amiodarone (n = 10) had a significantly lower risk of any clinically relevant ventricular arrhythmia (HR: 0.25, 95% CI: 0.07 to 0.95, p = 0.041), a finding that remained significant after multivariable adjustment. Conclusions In a cohort of well-characterized ARVC subjects, neither beta-blockers nor sotalol seemed to be protective. Evidence from a small number of patients suggests that amiodarone has superior efficacy in preventing ventricular arrhythmias.
African american women in therapy: an afrocentric and feminist synthesis

Theoretical and cultural issues related to the treatment of African-American women are explored, with particular emphasis on the utility of two psychological models for use with this group. The Afrocentric and feminist orientations of psychology are examined as they address the unique condition of African American women. A synthesis of these models is proposed to more accurately describe the experiences of African American women, and examples of cultural issues that may emerge in therapy are considered within the context of this integrated model.
Intraosseous leiomyoma of the ulna. A case report.

Leiomyomas are benign smooth-muscle tumors that most commonly arise in the uterus, the gastrointestinal tract, and the skin. They constitute 70% to 80% of all benign mesenchymal tumors, with uterine leiomyomas being the most common smooth-muscle tumor in women1. Leiomyomas are infrequently seen in the extremities2-6 and are rarely seen in bone. To the best of our knowledge, the only reported intraosseous leiomyomas occurred in the proximal aspect of the femur7, in the tibia4,8, and in the mandible9,10. We are not aware of any previous reports of intraosseous leiomyomas in the upper extremity. We describe the case of a patient with a painful intraosseous leiomyoma involving the distal aspect of the ulna. Our patient was informed that data concerning the case would be submitted for publication. Athirty-eight-year-old, left-hand-dominant woman presented with a ten-year history of ulnar pain in the left wrist. The medical history, including that for gynecological disorders, was negative. Initially, the pain had been mild, but four years before the patient presented at our institution, the symptoms began to worsen. The patient took nonsteroidal anti-inflammatory medication for approximately three months, with transient relief of symptoms. However, two years later, the pain again worsened and began to limit the range of motion of the left wrist and forearm. Physical examination revealed moderate, diffuse swelling along the ulnar dorsal aspect of the left wrist. Palpation of the distal aspect of the ulna caused extreme pain that was centered mostly about the ulnar styloid and the …
Residual strength characterization of laminated composites subjected to impact loading

Abstract : An analogy between damage inflicted by a single point hard particle impact and damage inflicted by inserting a flaw of known dimensions in a static tensile coupon is discussed. The results suggest that residual strength can be predicted as a function of kinetic energy of impact by executing two experiments, a static tensile test on an unflawed specimen and a static tensile test on a coupon previously subjected to a single point impact. The model appears to be accurate for impact velocities which are less than the penetration velocity. For velocities above complete penetration, the residual strength is identical to the static strength of a coupon with a hole having the same diameter as the impacting particle. Comparison of various materials indicates that the impact strength of composite materials is strongly influenced by the strain energy to failure of the reinforcement. (Author)
Bacterial quorum sensing and nitrogen cycling in rhizosphere soil.

Plant photosynthate fuels carbon-limited microbial growth and activity, resulting in increased rhizosphere nitrogen (N)-mineralization. Most soil organic N is macromolecular (chitin, protein, nucleotides); enzymatic depolymerization is likely rate-limiting for plant N accumulation. Analyzing Avena (wild oat) planted in microcosms containing sieved field soil, we observed increased rhizosphere chitinase and protease specific activities, bacterial cell densities, and dissolved organic nitrogen (DON) compared to bulk soil. Low-molecular weight DON (<3000 Da) was undetectable in bulk soil but comprised 15% of rhizosphere DON. Extracellular enzyme production in many bacteria requires quorum sensing (QS), cell-density dependent group behavior. Because proteobacteria are considered major rhizosphere colonizers, we assayed the proteobacterial QS signals acyl-homoserine lactones (AHLs), which were significantly increased in the rhizosphere. To investigate the linkage between soil signaling and N cycling, we characterized 533 bacterial isolates from Avena rhizosphere: 24% had chitinase or protease activity and AHL production; disruption of QS in 7 of 8 eight isolates disrupted enzyme activity. Many {alpha}-Proteobacteria were newly found with QS-controlled extracellular enzyme activity. Enhanced specific activities of N-cycling enzymes accompanied by bacterial density-dependent behaviors in rhizosphere soil gives rise to the hypothesis that QS could be a control point in the complex process of rhizosphere N-mineralization.
A computer based method for computing the N-dimensional generalized ABCD parameter matrices of N-dimensional systems with distributed parameters

The author presents a method for developing and solving, both in transient and steady state, the N-dimensional matrix networks of N-dimensional transmission line networks or communication circuits with distributed parameters. The method uses the Cayley-Hamilton theorem to compute the hyperbolic N-dimensional generalized ABCD parameter matrices with finite terms, which are fundamental to the solution of N-dimensional matrix networks. The square root function of a complex matrix is also computed with finite terms. As a result, truncation of matrices is eliminated. The method is extremely useful in the fault analysis of N-dimensional unbalanced coupled systems with distributed parameters. >
The coming of Keynesianism to America: Conversations with the founders of Keynesian economics: Edited by David C. Colander and Harry Landreth Brookfield, VT: Edward Elgar, 1996, 220 pages

(1997). The coming of Keynesianism to America: Conversations with the founders of Keynesian economics. The Social Science Journal: Vol. 34, No. 3, pp. 414-416.
Rapid and label-free screening of enzyme inhibitors using segmented flow electrospray ionization mass spectrometry

Electrospray ionization mass spectrometry (ESI-MS) is an attractive analytical tool for high-throughput screening because of its rapid scan time and ability to detect compounds without need for labels. Impediments to the use of ESI-MS for screening have been the relatively large sample consumed and slow sample introduction rates associated with commonly used flow injection analysis. We have previously shown that by segmenting nanoliter plugs of sample with air, an array of discrete samples can be delivered to a platinum-coated emitter tip for ESI-MS analysis with throughput as high as 0.8 Hz and carry-over between samples less than 0.1%. This method was applied to screening for inhibitors of acetylcholinesterase as a demonstration of the potential of segmented flow ESI-MS for such applications. Each enzyme assay consumed 10 nL of sample. At 1 μL/min infusion rate, 102 samples were analyzed, corresponding to a 0.65 Hz sample analysis rate. Linear quantification of choline was achieved from 200 μM to 10 mM using this method and Z′ values were over 0.8 for the assay. Detailed pharmacologic dose-response curves of selected inhibitors were also measured in high-throughput fashion to validate the method.
Low energy process variation tolerant digital image processing system design based on accuracy-energy tradeoffs

In this paper, we present a low energy image processing system design based on efficient accuracy-energy tradeoffs. The proposed design allows aggressive voltage scaling in the presence of process variation by employing an error concealing method based on the inherent error tolerance of digital signal processing applications. Based on a system-level analysis, we demonstrate that significant energy savings can be achieved from voltage scaling and switching activity reduction for computational components. Using the proposed method, we can also achieve energy savings for other subsystems such as memory by increasing compression ratio. The experimental results show that average overall energy savings of up to ∼50% are possible over a conventional design in a 45nm technology.
Transfer of the supinator muscle to the extensor pollicis brevis for thumb extension reconstruction in C7-T1 brachial plexus palsy

With C7-T1 brachial plexus injuries, finger motion is absent while shoulder, elbow and wrist function are largely preserved. Previously, we have reconstructed finger flexion by transferring the brachialis muscle to the flexor digitorum profundus and flexor pollicis longus; and we have restored extension of thumb and finger by transferring the motor nerve to the supinator to the posterior interosseous nerve, which is only feasible in fresh injuries. We describe the transfer of the supinator muscle to the extensor pollicis brevis to reanimate thumb extension in patients with long standing C7-T1 brachial plexus palsy.
Molecular dissection of the folding mechanism of the alpha subunit of tryptophan synthase: an amino-terminal autonomous folding unit controls several rate-limiting steps in the folding of a single domain protein.

The alpha subunit of tryptophan synthase (alphaTS) from Escherichia coli is a 268-residue 8-stranded beta/alpha barrel protein. Two autonomous folding units, comprising the first six strands (residues 1-188) and the last two strands (residues 189-268), have been previously identified in this single structural domain protein by tryptic digestion [Higgins, W., Fairwell, T., and Miles, E. W. (1979) Biochemistry 18, 4827-4835]. The larger, amino-terminal fragment, alphaTS(1-188), was overexpressed and independently purified, and its equilibrium and kinetic folding properties were studied by absorbance, fluorescence, and near- and far-UV circular dichroism spectroscopies. The native state of the fragment unfolds cooperatively in an apparent two-state transition with a stability of 3.98 +/- 0.19 kcal mol(-1) in the absence of denaturant and a corresponding m value of 1.07 +/- 0.05 kcal mol(-1) M(-1). Similar to the full-length protein, the unfolding of the fragment shows two kinetic phases which arise from the presence of two discrete native state populations. Additionally, the fragment exhibits a significant burst phase in unfolding, indicating that a fraction of the folded state ensemble under native conditions has properties similar to those of the equilibrium intermediate populated at 3 M urea in full-length alphaTS. Refolding of alphaTS(1-188) is also complex, exhibiting two detectable kinetic phases and a burst phase that is complete within 5 ms. The two slowest isomerization phases observed in the refolding of the full-length protein are absent in the fragment, suggesting that these phases reflect contributions from the carboxy-terminal segment. The folding mechanism of alphaTS(1-188) appears to be a simplified version of the mechanism for the full-length protein [Bilsel, O., Zitzewitz, J. A., Bowers, K.E, and Matthews, C. R.(1999) Biochemistry 38, 1018-1029]. Four parallel channels in the full-length protein are reduced to a pair of channels that most likely reflect a cis/trans proline isomerization reaction in the amino-terminal fragment. The off- and on-pathway intermediates that exist for both full-length alphaTS and alphaTS(1-188) may reflect the preponderance of local interactions in the beta/alpha barrel motif.
The long-term effects of small classes in early grades: lasting benefits in mathematics achievement at grade 9

Abstract Reducing class size to increase academic achievement is a policy option currently of great interest. Although the results of small-scale randomized experiments and some interpretations of large-scale econometric studies point to positive short-term effects of small classes, some scholars view the evidence as ambiguous. Project STAR in Tennessee-a 4-year, large-scale randomized experiment on the effects of class size—provided persuasive evidence that small classes have immediate positive effects on academic achievement. Unlike most other early education interventions, these effects persisted for several years after the children returned to regular-sized classes. The authors of the present article report analyses of a 6-year follow-up of the students in that experiment. Class-size effects persisted for at least 6 years and remained large enough to be important for educational policy. The results suggest that small classes in early grades have lasting benefits and that those benefits are greater for...
PERTURBATION ANALYSIS AND FEEDBACK CONTROL OF COMMUNICATION NETWORKS USING STOCHASTIC HYBRID MODELS

Abstract Communication networks may be abstracted through Stochastic Fluid Models (SFM) with the node dynamics described by switched flow equations as various events take place, thus giving rise to hybrid automaton models with stochastic transitions. The inclusion of feedback mechanisms complicates these dynamics. In a tandem setting, a typical feedback mechanism is the control of a node processing rate as a threshold-based function of the downstream node's buffer level. The problem considered here is to control the threshold parameters so as to optimize performance metrics involving average workload and system throughput and to show how Infinitesimal Perturbation Analysis (IPA) can be used to analyze congestion propagation through a network and develop gradient estimators of such metrics.
Molecular dynamics simulations of low-energy cluster deposition on metallic targets☆

A modified version of the multiple interaction code SPUT2 was used to simulate impacts of 63-atom Al and Au clusters on 7-layer Au targets. For 1, 5, and 10 eV/atom Al and Au clusters, 50 impacts each were calculated up to a cutoff time of 2 ps. For each case studied, we found that the final shape and penetration depth of the incoming cluster was almost independent of the initial cluster position relative to the target. The 1 and 5 eV/atom Al clusters were flattened to less than 40% of their initial thickness and exhibited registration with the substrate at 2 ps. The 10 eV/atom Al clusters formed a poorly registered monolayer on the Au surface. In these higher-energy collisions a significant number of Al atoms were reflected from the Au surface. The 1 eV/atom Au clusters were flattened to approximately 60% of their initial thickness and also exhibited clear registration with the substrate at 2 ps. Higher-energy Au clusters penetrated deeply into the targets, causing substantial damage and crater formation.
Expression of scFv antibodies in Xenopus embryos to disrupt protein function: implications for large-scale evaluation of the embryonic proteome.

Summary: We evaluated the use of single-chain antibody (scFv) expression as a tool to disrupt the function of specific proteins in embryos of the frog, Xenopus laevis. The expression of scFvs that recognize the bone morphogenetic protein receptor (ALK3) or the fibroblast growth factor receptor1 (FGFR1) as endoplasmic reticulum-anchored proteins caused distinct developmental defects that were virtually indistinguishable from the defects caused by expression of the dominant negative forms of each receptor. These results demonstrate that scFvs from phage-display libraries can be readily fashioned into effective and specific inhibitors of signaling pathways in developing embryos. In addition, as several effective scFvs against a specific target can be isolated rapidly, this approach represents a valuable new tool for large-scale functional analysis of the embryonic proteome. genesis 35:107–113, 2003. © 2003 Wiley-Liss, Inc.
Change in need for psychosocial support for women with early stage breast cancer.

Abstract To simulate the longitudinal needs of patients treated for breast cancer, 2 groups of women were recruited. Patients within 6 months of diagnosis were considered in the “early” group and those 6–12 months after diagnosis were categorized as the “late” group. Participants were asked to identify effective and ineffective methods of psychosocial support and how those needs changed. Thirty-one women participated in the focus groups. Women in the early group identified problems related to their surgery and chemotherapy; those in the late group focused on symptoms associated with menopause. An exaggerated fear of disease recurrence and death were common to both groups. Most women found it difficult to strike a balance between wanting emotional support and wanting to be treated as “normal.” The provision of concrete medical information in the form of pathology and laboratory reports and information from health care professionals provided comfort and control. Spouses and partners were helpful in providin...
A Semi-Synthetic Medium for Labelling Hemolytic Streptococci with Radioactive Phosphorus.

Summary(1) A detailed procedure for preparing a “phosphorus-free” protein hydro-lysate capable of supporting excellent growth of group A hemolytic streptococci in combination with other chemically defined constituents has been described. (2) This medium has been used successfully for tagging group A hemolytic streptococci with radiophosphorus.
Perceived discrimination and reported delay of pharmacy prescriptions and medical tests.

BACKGROUND: Access to health care varies according to a person’s race and ethnicity. Delaying treatment is one measure of access with important health consequences.
Creep Rupture Performance of Basalt Fiber-Reinforced Polymer Bars

AbstractFiber reinforced polymer (FRP) composite bars are suitable substitutes for steel reinforcement in structural concrete because of their light weight and high specific strength and stiffness. Sustained load on FRP composites over the entire service life of the structure can cause failure by creep rupture at loads much smaller than those corresponding to static transient loads. Creep rupture test methods used by several researchers are presented, and a suitable loading arrangement and test method were selected for this study. The creep rupture properties of basalt FRP bars were determined using sustained loading applied to the test specimens simultaneously with an alkaline solution at an elevated temperature. The tests were based on the method specified by the American Concrete Institute (ACI) in a standard. The ultimate creep rupture strength coefficients for basalt FRP bars were determined to be approximately 18% for 50 year service life and 28% for 5 year service life. The corresponding one millio...
SAR and BER evaluation using a simulation test bench for in vivo communication at 2.4 GHz

We present a simulation method and results that utilizes accurate electromagnetic field simulations to study the maximum allowable transmitted power levels from in vivo devices to achieve a required bit error rates (BER) at the external node (receiver) while maintaining the specific absorption rate (SAR) under a required threshold. The BER of the communication can be calculated using the derived power threshold for a given modulation scheme. These results can be used to optimize the transmitted power levels while assuring that the safety guidelines in terms of the resulting SAR of transmitters placed in any location inside the human body are met. To evaluate the SAR and BER, a software-based test bench that allows an easy way to implement field solver solutions directly into system simulations was developed. To demonstrate the software-based test bench design, a complete OFDM-based communication (IEEE 802.11g) for the in vivo environment was simulated. Results showed that for cases when noise levels increase or the BER becomes more stringent, a relay network or the use of multiple receive antennas, such as in a MIMO system, will be become necessary to achieve high data rate communication.
Caloric analyses of the distribution of energy in corn plants Zea mays L

Caloric calculations of the distribution of energy in HY 9919V, N8811, DK 714, and 3167 corn Zea mays L. plants at the V-10, R-1, R-4, and ripened stages were carried out by employing standard analytical techniques and subsequent calculations based on standard caloric values. For these analyses, plants were harvested, sectioned by tissue, dried, weighed, and subsequently analyzed for protein, crude fat, lignin, ash, cellulose, hemicellulose, and nitrogen-free solubles according to standard AOAC methods. In ripened corn, 45.8-48.7% of the dry weight and 47.9-50.3% of the caloric energy were found in the kernels, the remainder apportioned to the lower stalk, upper stalk, and cob. Energy distribution at the earlier stages in descending order were as follows: (V-10) leaves, whorl, roots; (R-1) lower stalk, upper stalk, ears, and tassels; and (R-4) cob, lower stalk, upper stalk, and husk. Thus, the corn plant is a relatively efficient producer of grain, to which it apportions ∼50% of its caloric energy. The development of corn that apportions an even higher percentage of its caloric energy to the production of grain may become a viable strategy for increasing yield.
Nitrogen Trifluoride: A New Reactant Gas in Chemical Reaction Interface Mass Spectrometry for Detection of Phosphorus, Deuterium, Chlorine, and Sulfur

A new set of reactions that involve fluorine have been investigated in chemical reaction interface mass spectrometry (CRIMS). The primary goal of this study was to provide a means to selectively detect phosphorus-containing compounds, which fluorine does by generating PF 5 . P F 4 + , the main fragment ion of PF 5 , provides a sensitive (10 pg/s), selective, and linear (> 10 5 dynamic range) channel for phosphorus-containing analytes. This fluorine-rich environment also provides new ways to selectively and simultaneously detect hydrogen isotopes, chlorine, and sulfur. NF 3 as a reactant gas provides the most comprehensive array of elemental and isotopic detection yet available for CRIMS. An application of phosphorus-selective detection was attempted by examination of a plasma sample from a patient who had been treated with cyclophosphamide. The phosphorus-selective channel showed six peaks: one is derivatized phosphate, two are t -butyldimethylsilyl (TBDMS) derivatives of cyclophosphamide, another two are TBDMS derivatives of 4-hydroxy-yclophosphamide, and one is from underivatized cyclophosphamide. The simultaneous detection of chlorinecontaining compounds confirmed our results for those peaks related to cyclophosphamide and its metabolite.
Impact of coffee on liver diseases: a systematic review

Coffee is one of the most commonly consumed beverages in the world. Its health benefits including improved overall survival have been demonstrated in a variety of disease states. To examine the association of coffee consumption with liver disease, a systematic review of studies on the effects of coffee on liver associated laboratory tests, viral hepatitis, nonalcoholic fatty liver disease (NAFLD), cirrhosis and hepatocellular carcinoma (HCC) was performed. Coffee consumption was associated with improved serum gamma glutamyltransferase, aspartate aminotransferase and alanine aminotransferase values in a dose dependent manner in individuals at risk for liver disease. In chronic liver disease patients who consume coffee, a decreased risk of progression to cirrhosis, a lowered mortality rate in cirrhosis patients, and a lowered rate of HCC development were observed. In chronic hepatitis C patients, coffee was associated with improved virologic responses to antiviral therapy. Moreover, coffee consumption was inversely related to the severity of steatohepatitis in patients with non-alcoholic fatty liver disease. Therefore, in patients with chronic liver disease, daily coffee consumption should be encouraged.
Simulations of multipactor breakdown in low-pressure background gas for angled dielectrics in DC

We report on 2D particle-in-cell (PIC) simulations of electrical breakdown incorporating single-surface multipactor with background-gas ionization. The system for study is a semi-infinite, two-electrode Bergeron geometry with an angled dielectric in steady-state fields, with a background gas at variable low pressure. For pressures below a few tens of Pa (a few hundred mTorr), discharges are dominated by multipactor breakdown initiated by a triple-point source; the breakdown condition is well-characterized by an average secondary-emission coefficient greater than unity at the onset of anodic current, otherwise a dark-current develops due to space-charge saturation. The magnitude of the anode current is driven by the development of a multipactor front comprising an enhanced current front followed by a steady-state tail in which dielectric-surface fields no longer support net secondary-emission, resulting in a non-multiplicative arc. Additional avalanche phenomena occur with increased pressure >133.3 Pa (>1 Torr), where space-charge coupling leads to oscillations in an otherwise DC discharge, largely driven by the development and quenching of the multipactor front.
Drug-Nitrite Interactions in Human Saliva: Effects of Food Constituents on Carcinogenic N-Nitrosamine Formation

A simple and rapid high-pressure liquid chromatographic assay for monitoring N-nitrosodimethylarnine (NDMA) in human saliva was developed. The method was used to study in vitro the effects of common food constituents on NDMA formation in saliva from the interaction of salivary nitrite with aminopyrine and oxytetracycline. Natural phenolic compounds, caffeic acid, and tannic acid, and synthetic additives, erythorbic acid, sorbic acid, propyl gallate, and butylated hydroxytoluene - all inhibited NDMA formation (20-80%). With ascorbic acid, up to 90% inhibition of NDMA synthesis in saliva was observed. In contrast, chlorogenic acid (a phenolic component of coffee) acted as a catalyst (up to 48% increase) of the nitrosamine formation under identical experimental conditions.
Depth distribution of 20-keV helium ion irradiation induced cavities in nickel

Transmission electron microscopy has been used to study the effect of total dose on the depth distribution of cavities (voids or bubbles) in nickel irradiated at 500/sup 0/C with 20-keV /sup 4/He/sup +/ ions. A transverse sectioning technique allowed us to obtain the entire depth distribution of cavities from a single specimen. The diameter, number density and volume fraction of cavities were measured as a function of depth from micrographs taken from samples sectioned parallel to the direction of the incident beam. Results for the doses at 2.9 x 10/sup 15/ and 2.9 x 10/sup 16/ ions/cm/sup 2/ show an increase in the average cavity diameter, number density and volume fraction with increasing dose. A further increase in dose from 2.9 x 10/sup 16/ to 2.9 x 10/sup 17/ ions/cm/sup 2/ also shows an increase in the average cavity diameter but a decrease in the number density. This observation is interpreted as evidence for the coalescence of cavities. 3 figures, 1 table.
Forage preferences in two species of prairie dog (Cynomys parvidens and Cynomus ludovicianus): implications for hibernation and facultative heterothermy

Several laboratory studies have shown that the ingestion of dietary linoleic (18:2 ω6) acid before winter can promote deep and continuous torpor, whereas excess consumption of α-linolenic acid (18:3 ω3) can interfere with an animal's ability to reach and maintain low body temperatures during torpor. As mammalian heterotherms obtain linoleic and α-linolenic acid strictly from the diet, diet selection has been proposed as a mechanism that allows hibernators to ingest levels of linoleic and α-linolenic acid that promote favorable torpor patterns. Here diet, dietary nutrient content and patterns of forage preference of a representative hibernator, the Utah prairie dog Cynomys parvidens, and a facultative heterotherm, the black-tailed prairie dog Cynomys ludovicianus, were examined under natural field conditions. Diets of black-tailed (BTPD) and Utah prairie dogs (UTPD) differed across seasons (BTPD F26,108=9.59, P<0.01; UTPD F38,80=3.25, P<0.01) and elevations (BTPD F26,108=20.15, P<0.01; UTPD F38,80=20.51, P<0.01), and forage preference indices indicate that neither species randomly selected plant species relative to their abundance on colonies in any season. Black-tailed prairie dogs did not consume or avoid consumption of plant species based on levels of total lipids, linoleic acid, α-linolenic acid or nitrogen. Considering only the plants consumed, black-tailed prairie dogs appeared to prefer plants with low levels of α-linolenic acid (F1,19=5.81, P=0.03), but there were no detectable relationships between preference and other nutrients. Utah prairie dogs consumed plants higher in α-linolenic acid (t=1.98, P=0.05) and avoided plants high in linoleic acid (t=−2.02, P=0.04), but consumption-avoidance decisions did not appear to be related to nitrogen or total lipids. Of the plants consumed, Utah prairie dogs again preferred plants high in α-linolenic acid (F1,17=4.62, P=0.05). Levels of linoleic and α-linolenic acid were positively correlated in plants consumed by prairie dogs (BTPD Pearson r=0.66, P<0.01; UTPD Pearson r=0.79, P<0.01), reducing the opportunity for independent selection of either lipid.
Risk of transmission of human immunodeficiency virus by bite of an infected toddler.

Un enfant infecte par le HIV-1 a mordu, a l'âge de 36 mois, 4 cousins et un 5eme cousin porteur de lesions cutanees a ete en contact avec son urine. Aucun des 5 enfants suivis durant 20 mois ne semble avoir ete contamine. Quatre autres cas publies sont discutes dont 1 seroconversion d'origine mal precisee