cssi/SciSciGPT-SciSciNet huggingface dataset:
Optimization of spatially distributed systems with spatially local controllers and partial connectivity

This paper presents two different design approaches of networked distributed controllers for a class of partial differential equations. Such a work attempts to reduce controller complexity by opting to control a spatially distributed process by a network of interconnected control units. This approach reduces the need to use a centralized controller that must fuse sensory information by the distributed sensors and then dispense the controllers to the spatially distributed process via the spatially distributed actuators. In the first approach, the controller gains used to implement the local controllers by the controller units, along with the actuator and sensor location and the network connectivity are optimized by formulating the optimization problem into a minimization problem of an appropriately chosen performance measure of the closed-loop system. This takes the form of a parameterized operator Lyapunov equation whose optimal solution provides the optimal (proportional) controller gains, the optimal locations of the actuators and sensors, and the optimal network connectivity. The second approach considers the adaptation of the gains of the distributed controllers using Lyapunov-redesign methods to extract their adaptation. The well-posedness and convergence properties of the proposed controllers are summarized and numerical studies examining various aspects of the proposed work are presented.
Irreversible gibbsian ensembles

Abstract In this paper we continue the investigation of a model for the description of irreversible processes which we had proposed in an earlier publication. This model permits the construction of Gibbs-type ensembles for open systems not in equilibrium. The internal dynamics of the system that is engaged in a nonequilibrium process is assumed to be described fully by its Hamiltonian. Its interaction with its surroundings, i.e. the driving reservoirs, is described in terms of impulsive interactions (collisions). The reservoirs themselves possess definite temperatures, are inexhaustible, and are free of internal gradients (i.e. they are temperature baths). The ensemble obeys an integro-differential equation in Γ-space, containing both the terms of the Liouville equation and a stochastic integral term that describes the collisions with the reservoirs. It is shown in this paper that, under very general assumptions, all distributions approach each other in the course of time. If there exists a stationary solution, it will be unique and will be approached asymptotically by every time-dependent solution. In general the stationary state does not represent thermodynamic equilibrium; the ensemble remains unchanged only because its surroundings maintain temperature gradients inside the thermodynamic system. Only if these surroundings are all at one temperature, i.e. if the system is in contact with but one reservoir, then the stationary state will correspond to the canonical distribution. As a result, the stochastic integral kernel that describes the effect of collisions with the reservoir will satisfy certain symmetry conditions. A detailed investigation of our micro-model shows that these conditions are indeed satisfied if the reservoir components are themselves in a canonical distribution prior to collision. In the presence of several reservoirs at slightly different temperatures, the Onsager reciprocal relations are satisfied by the stationary distribution. In our model the Onsager relations are thus obtained without an appeal to fluctuation theory, and without the assumption that detailed balancing holds for the elementary stochastic processes, i.e. for the interactions between system and reservoir. In the latter part of the paper, finally, we consider reservoirs that maintain thermodynamic potentials in addition to the temperature, including chemical potentials. It turns out that our principal results are unaffected by this generalization.
A standard model from the E(8) x E(8) heterotic superstring

In a previous paper, we introduced a heterotic standard model and discussed its basic properties. This vacuum has the spectrum of the MSSM with one additional pair of Higgs-Higgs conjugate fields and a small number of uncharged moduli. In this paper, the requisite vector bundles are formulated; specifically, stable, holomorphic bundles with structure group SU(N) on smooth Calabi-Yau threefolds with Z_3 x Z_3 fundamental group. A method for computing bundle cohomology is presented and used to evaluate the cohomology groups of the standard model bundles. It is shown how to determine the Z_3 x Z_3 action on these groups. Finally, using an explicit method of "doublet-triplet splitting", the low-energy particle spectrum is computed.
Atmospheric thermometry for metallic surfaces by laser-induced second-harmonic generation

To the best of our knowledge we report the first demonstration of surface thermometry using laser-induced second-harmonic generation (SHG) on a realistic metallic surface at atmospheric pressure. The surface is probed with a pulsed infrared laser beam and the SHG signal is monitored in reflection. For metallic silver, the SHG signal is found to be temperature dependent in the 25–120 °C range. The current accuracy of the method is ±5 °C. Future work with platinum should permit the application of SHG thermometry to much higher surface temperatures.
Amino acid pairing

Abstract A set of amino acid pairings are presented which may allow protein-to-protein information transfers. Amino acid pairing is only possible on a parallel β ribbon and involves both the polypeptide backbones and the side chains. Model building revealed that of the 210 possible amino acid pairs of the standard 20 amino acids, no more than 26 could be built to meet standard criteria for bonding. Of these 26, 14 were found to be genetically encoded when the codons are read as if they paired in a parallel manner (i.e. in a manner reflecting the structural parallelism of the amino acid pairings); the other 12 pairings were derivatives of the coded pairings in which a single base of the codon triplet had been varied in accordance with Crick's (1966) “wobble hypothesis.” Evidence for the pairings is presented from colligative studies of polyamino acids. Ways of testing the hypothesis further are suggested. Its implications for the Central Dogma and theories of the origin of life are discussed.
Restriction fragment length polymorphisms in satellite DNA distinguish chromosomal races of the white‐footed mouse Peromyscus leucopus

We describe a polymorphism revealed by a high-copy-number tandem repeat which serves to distinguish most individuals sampled (96%) from two chromosomal races of Peromyscus leucopus. Classical morphology, allozymes, mtDNA, and rDNA have all failed to provide fixed markers which separate these two chromosomal races. Data from P. leucopus further documents the utility of DNA polymorphisms to establish the natal origin (DNA ‘zipcodes’) of populations or individuals.
Graphite Sublimation Tests for Target Development for the Muon Collider/Neutrino Factory

Graphite sublimation tests have been conducted in a high-temperature oven, which is operated either in high vacuum or in an 1-atm cover gas of helium (or argon). Preliminary data of the sublimation rate of graphite foils at ~2400 K in vacuum are consistent with theoretical prediction. Additional tests of graphite rods (15 mm in diameter and 300 mm long) have been conducted in high vacuum and in cover gases of helium as well as argon. The sublimation mass loss rate at 2350 K is 1.7 mg/h for static argon cover gas (>1 atm) and 0.78 mg/h for static helium cover gas. These values of sublimation mass loss rate for cover gas cases are lower than that of 5.8 mg/h in high vacuum. This unique approach of using cover gas to reduce sublimation rate could allow a robust radiatively cooled graphite target for the Muon Collider/Neutrino Factory as proposed in the conceptual design study. In this paper, the results of graphite sublimation tests, including the test setup and test procedure, are presented and discussed
The effect of body size on male courtship success in a plethodontid salamander

Abstract Two different sets of courtship encounters between female Desmognathus ochrophaeus and males of large ( X¯ =58) and small ( X¯ =38 mm) body size were staged in the laboratory. In the first set, encounters were arranged between male-female pairs so that each of five females individually encountered each of 10 males. In these encouters, small and large males were equally likely to court with and inseminate females. In the second set, each encounter was staged for a trio fo one female and two males (one large and one small); each female had a courtship opportunity with five large-small pairs of males, and each pair of males encountered five different females. In the 25 trio encounters, the large male always chased away the small male before proceeding to court the female. Small males never deposited spermatophores if a large male was present. Male body size should have a significant effect on courtship success in natural populations of D. ochrophaeus if male-male competition affects access to females.
3-Methoxy-4-hydroxyphenethyleneglycol production by human brain in vivo

A direct method has been employed to estimate the rate of production by human brain of 3-methoxy-4-hydroxyphenethyleneglycol, the major metabolite of brain norepinephrine, a brain neurotransmitter. Venous specimens were obtained from the internal jugular vein from ten awake human subjects at a puncture site above the common facial vein, the first major source of extracranial inflow. Arterial specimens were simultaneously obtained from the radial artery. Plasma samples were assayed and a highly significant difference was found in the concentration of the metabolite in plasma coming out of the brain (venous blood) as compared to plasma entering the brain (arterial blood). This venous-arterial difference was calculated to be 0.7 +/- 0.1 nanogram per milliliter of blood. Assuming an adult brain weight of 1400 grams and normal cerebral blood flow, it is estimated that the rate of production of 3-methoxy-4-hydroxyphenethyleneglycol by the awake human brain is approximately 597 nanograms per minute or 35.8 micrograms per hour. Urine specimens were also collected from six of these subjects during a period of 1 to 3.5 hours, which bracketed the time the blood samples were obtained. For these six subjects the output of 3-methyoxy-4-hydroxyphenethyleneglycol by whole brain was estimated to be 40.9 micrograms per hour, whereas the rate of its excretion into urine was 64.5 micrograms per hour.
Long-term changes in forest soil acidity in Pennsylvania, U.S.A.

Forest soil acidification has been reported to cause reduced forest productivity and decline of some tree species. Soil acidification may cause increased bioavailability of Al and Mn, which are potentially phytotoxic. In an attempt to measure whether or not Pennsylvania forest soils have become more acidic, soil samples were collected at 11 undisturbed forested sites in Pennsylvania in 1993. Limited soil chemistry data obtained through 4 previous studies conducted between 1957 and 1979 were available for each site. Soil pH and concentrations of exchangeable Ca and Mg were measured; results were compared to those obtained in earlier studies. Soil exchangeable Al concentrations were determined for 6 sites for which previous data were available. Chemical analysis methods were evaluated to ensure that methods used in 1993 were comparable to those of the original investigators. Mean pH and exchangeable Mg declined most consistently over the study period in the O horizon and the uppermost A horizon. Mean exchangeable AI decreased in the O horizon and increased in the A horizon. Given the high sulfate and nitrate deposition loads in Pennsylvania, it seems likely that the observed changes are at least in part a consequence of acidic deposition.
Modeling effects of axial extension on arterial growth and remodeling

Diverse mechanical perturbations elicit arterial growth and remodeling responses that appear to optimize structure and function so as to promote mechanical homeostasis. For example, it is well known that functional adaptations to sustained changes in transmural pressure and blood flow primarily affect wall thickness and caliber to restore circumferential and wall shear stresses toward normal. More recently, however, it has been shown that changes in axial extension similarly prompt dramatic cell and matrix reorganization and turnover, resulting in marked changes in unloaded geometry and mechanical behavior that presumably restore axial stress toward normal. Because of the inability to infer axial stress from in vivo measurements, simulations are needed to examine this hypothesis and to guide the design of future experiments. In this paper, we show that a constrained mixture model predicts salient features of observed responses to step increases in axial extension, including marked increases in fibrous constituent production, leading to a compensatory lengthening that restores original mechanical behavior. Because axial extension can be modified via diverse surgical procedures, including bypass operations, and exploited in tissue regeneration research, there is a need for increased attention to this important aspect of arterial biomechanics and mechanobiology.
The abiocor artificial replacement heart: Bioengineering meets bioethics

ON JULY 2, 2001, medical history was made when the first totally self-contained artificial heart was implanted into a terminally ill patient at Jewish Hospital in Louisville, Kentucky. During a 7-hour operation, performed by Gray and Dowling of the University of Louisville, the patient’s irreparably damaged heart was removed and replaced with a 2-lb AbioCor device (Abiomed Corporation, Danvers, MA). In contrast to other artificial hearts, the AbioCor device is not designed as a bridge to transplant but as a permanent replacement, and it contains no pumps or wires outside of the patient’s body. It is powered by a transdermal battery pack. Important questions of bioethics were raised almost immediately on the realization of the implications of this technologic achievement. This article reviews the important bioethics issues raised by the artificial heart. The issues are placed into 2 main categories—issues involving the ethics of clinical research and issues that deal with the distributional ethics of whether it is appropriate to spend scarce health resources on high-cost, hightech medical devices and, if so, who should have access to this technology. The more abstract ethical issues of the use of artificial replacement organs in humans are not discussed.
Towards Reconceptualizing Political Action

The discipline of sociology faces important challenges that may result in a transformation of the field. For example, the practice of specialization potentially takes on a new meaning in the context of growing interdisciplinary studies, the growth of feminist scholarship, and renewed efforts at micro-macro linkages. In essence, more comprehensive accounts of social phenomena are made possible as a result of these trends. This paper examines the way in which such approaches may lead to advances in the study of political action.
Cellular Physiology of the Retina

Cellular activities of the retina are discussed in relation to the maintenance of the internal environment of the organ and the preservation of cell life, including the most important manifestation of disturbed retinal cell life, the degeneration of the visual cells on a hereditary basis. In regard to the former activities, the role of the “nonneuronal” cells is stressed, especially that of the pigment epithelium which seems to be the site of generation of a major fraction of the steady (dc) potential across the mammalian retina, and also of the “slow” potentials resulting from changes in retinal illumination. A new technique permitting the measurement of transretinal currents at constant (“clamped”) voltages and of transretinal ion fluxes is described. Preliminary experiments indicate that the dc potential originates from differences in active and passive potassium ion movements through the two planar surfaces of the pigment epithelium. Structural differences of these surface regions are related to the experimental findings, and the pigment epithelium is viewed as a “living barrier” between body and visual cell layers. Bruch’s membrane, to which much importance has been attached by others in relation to electrical phenomena, is considered to provide “mechanical” support for the retina, its electrophysiological properties to be negligible in first approximation relative to those of the plasma membrane of the pigment epithelial cell. The main energetic support of the retinal cells derives from the catabolism of glucose, its degradation to lactic acid and oxidation mainly by the citric acid cycle. A deficiency in energy-yielding processes of glucose metabolism is not the basic abnormality which leads, on a hereditary basis, to visual cell death during the first weeks (or months) of the postnatal life in certain mouse and rat strains. Phenomena of this disease are described from various points of view, and it is emphasized that a deficiency in rhodopsin synthesis does not exist; on the contrary, retinal rhodopsin concentration increases while the visual cells deteriorate functionally. The genetic abnormality seems to involve primarily a control factor that directs by unknown mechanisms visual cell development and differentiation to the functional state.
Changes in leucyl- and tyrosyl-tRNA of soybean cotyledons during plant growth.

Abstract 1. 1. Soybean cotyledons were used to determine changes in leucyl- and tyrosyl-tRNA's with seedling age. Two of the six leucyl-tRNA's from cotyledons quantitatively increase with age, between 2 and 15 days. Tyrosyl-tRNA, which is separable into three fractions, shows a sharp decrease in Species 2 and a simultaneous increase in Species 3 over the same period of time. 2. 2. Treatment of seeds with a cytokinin had no effect on the tyrosyl-tRNA's, but accelerated the age-related changes which occur in leucyl-tRNA's. 3. 3. It is concluded that as the soybean cotyledons are depleted of their storage materials and begin to senesce, quantitative changes in leucyl- and tyrosyl-tRNA ensue. The significance of these changes in relation to senescence is discussed.
Morphological Operator Distributions Based On Monotonicity And The Problem Posed By Digital Disk-Shaped Structuring Elements

A sequence of structuring elements S = {S1,...,SN} is said to be increasing if it has the property that for each i, Si+i ⊃ Si. In general, such sequences are made up of elements with similar shapes but different sizes; e. g., lines, squares, octagons, and disks. A morphological operation ψ is said to be monotonic with respect to an Increasing structuring element sequence S, if, for any set X, either: (X 'F Si+1) 2 (X 'F Si), Vi (Monotonic increasing) Or (X AIF Si) 3 (X III Si+1), Vi (Monotonic decreasing) Dilation is monotonic increasing while erosion is monotonic decreasing. These properties make it possible to unambiguously classify every pixel in a binary image by associating each with one of the elements in the sequence S. Morphological openings and closings are also monotonic, but only if an additional property holds for the sequence 5, namely, that for each i, there exists a structuring element T such that Si+1 = (Si ⊕ T), or in other words, Si and Si+1 must be similar in shape up to a dilation. In the digital world, squares, hexagons, and octagons are similar but digital approximations to disks are not. This poses problems for trying to generate morphological shape and size distributions based on very accurate digital disks. This paper proves the monotonicity properties for erosions, dilations, openings, and closings, and shows how pixel distributions or classifications based on shape can be generated from these properties. It also discusses the problem posed by digital disks, and describes one method of circumventing it.© (1988) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Development of an optically controlled phased array

In order to achieve a wideband and wide-angle electronically scanned antenna, Hughes has been working under an ARPA/Rome Lab Program to develop an L-band 96-element phased array antenna that incorporates fiber optic remoting of RF and digital control signals as well as a true-time delay beam steering mechanism. The true-time delay is accomplished by a combination of fiber optic and microwave stripline programmable delays.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
Transduction studies on the role of a rec+ gene in the ultraviolet induction of prophage lambda.

The rec+ gene was introduced into Escherichia coli K12 rec− mutant bacteria by transduction with phage P1. Both abortive and complete transduction occur at frequencies of 2 × 10−4 and 2 × 10−5 per adsorbed P1 respectively. Transduction of the rec+ gene to rec−λs bacteria is evidenced by an increased resistance to ultraviolet light; transduction to rec−(λ) bacteria results in the appearance of the capacity to produce λ phage after ultraviolet irradiation. An analysis of the causes for the failure of rec−(λ) bacteria to produce λ phage after ultraviolet treatment indicated that, in the absence of the rec+ gene, the immunity repressor remains active after irradiation. The effect of ultraviolet light persists, however, and can be revealed even two hours later by introduction of the rec+ gene. Some implications of these findings for the mechanisms of prophage induction by ultraviolet light are discussed.
Evidence for two methyltransferases involved in the conversion of phosphatidylethanolamine to phosphatidylcholine in the rat liver

Abstract The stepwise methylation of phosphatidylethanolamine (PE) to phosphatidylcholine (PC) occurs in the rat liver. The properties of two methyltransferases that are involved in this stepwise methylation of PE to PC in the rat liver are reported. Rat microsomal membranes were used as the source of the enzymes and S -adenosyl- l -[methyl- 3 H]methionine as the methyl donor. The first methyltransferase converted PE to phosphatidyl- N -methylethanolamine (PME), and the second methyltransferase converted PME to PC. The products were characterized by thin-layer chromatography and high-pressure liquid chromatography. After incubation of rat liver microsomes with the methyl donor, three peaks corresponding to PME, dimethyl-PME (PMME), and PC were found and quantified. The first methyltransferase had low K m (0.83 μ m ), pH optimum of 8, and was activated by Mg 2+ . The second methyltransferase had a high K m (~67 μ m ) and a pH optimum of 10. The proportion of the first methyltransferase in the microsomal membranes was increased by repeated washings in hypotonic medium containing EDTA. When the microsomal membranes were subjected to repeated mild sonication and centrifugation at 105,000 g a fraction of the second methyltransferase was solubilized (i.e., appeared in the nonparticulate fraction). The solubilized enzyme utilized dipalmitoyl-PME and -PMME as substrates. Both enzymes were also present in mitochondrial and nuclear membranes with highest specific activities occurring in the microsomal membranes.
Multi-segment continuum robot shape estimation using passive cable displacement

This paper describes a state estimation model for a multi-segment continuum robot that utilizes the displacement of passive cables embedded along the robot's length to estimate its overall shape. As continuum robots are used in activities outside a laboratory environment, methods of measuring their shape configuration in real-time will be necessary to ensure robust closed-loop control. However, because these robots deform along their entire length and lack discrete joints at which primary displacements take place, conventional approaches to sensing joint displacement (e.g., encoders) are inappropriate. Furthermore, elasticity plays a key role in determining the resulting shape of the continuum robot, instead of the mechanics-independent kinematic configuration frequently seen in rigid-link robotics. In order to enable accurate estimates of a continuum robot's shape, the measured displacements of passive cables are utilized to detect the change in shape of the continuum robot. An optimization is used with a static model based on the principle of virtual power to map these cable displacements into the resulting continuum robot configuration. This state estimation model was implemented numerically in MATLAB and validated on an experimental test platform.
Probing membrane topology by high-resolution 1H-13C heteronuclear dipolar solid-state NMR spectroscopy.

Abstract Membrane topology changes introduced by the association of biologically pertinent molecules with membranes were analyzed utilizing the 1 H– 13 C heteronuclear dipolar solid-state NMR spectroscopy technique (SAMMY) on magnetically aligned phospholipid bilayers (bicelles). The phospholipids 1 H– 13 C dipolar coupling profiles lipid motions at the headgroup, glycerol backbone, and the acyl chain region. The transmembrane segment of phospholamban, the antimicrobial peptide (KIGAKI) 3 and cholesterol were incorporated into the bicelles, respectively. The lipids 1 H– 13 C dipolar coupling profiles exhibit different shifts in the dipolar coupling contour positions upon the addition of these molecules, demonstrating a variety of interaction mechanisms exist between the biological molecules and the membranes. The membrane topology changes revealed by the SAMMY pulse sequence provide a complete screening method for analyzing how these biologically active molecules interact with the membrane.
Translation of the Diabetes Prevention Program’s Lifestyle Intervention: Role of Community Health Workers

Approximately 8.3% of the US population has diabetes and estimates indicate that 79 million adults have prediabetes and 33.8% are obese, increasing their risk of diabetes. The national Diabetes Prevention Program (DPP) and subsequent translation studies have demonstrated the efficacy of the DPP lifestyle intervention (DPPLI) on lowering weight and reducing risk of type 2 diabetes over 10 years. Innovative strategies are needed to translate the DPPLI to reach people at risk of diabetes. Community health workers represent a group of individuals poised to play a role in supporting the translation of the DPPLI, especially in underserved populations. This article aims to 1) describe community health workers in general; 2) describe their role and impact on diabetes care in general; and 3) provide a detailed overview of studies involving community health workers in the translation of the DPPLI.
Myocardial blood flow and efficiency in concentric and eccentric left ventricular hypertrophy

Abstract Background It is not clearly understood why concentric left ventricular hypertrophy (increased left ventricular mass and relative wall thickness) is associated with higher cardiovascular risk than eccentric hypertrophy (increased left ventricular mass but normal relative wall thickness). Possible reasons include lower myocardial efficiency or perfusion reserve in concentric than in eccentric hypertrophy. We compared myocardial perfusion reserve and efficiency in normotensive controls and in hypertensive patients with concentric and with eccentric hypertrophy. Methods Study subjects comprised 16 patients with hypertension-induced left ventricular hypertrophy and 10 normotensive controls. We measured myocardial perfusion reserve and oxygen consumption by positron emission tomography. We calculated myocardial efficiency by dividing left ventricular minute work by myocardial oxygen consumption. Results There was no significant difference in myocardial perfusion reserve between patients with concentric (n = 9) as compared to eccentric (n = 7) hypertrophy. However, myocardial perfusion reserve in both patient groups were lower than in controls. Although myocardial efficiency in patients with eccentric hypertrophy and in controls were not different, both values were higher than measurements in patients with concentric hypertrophy (18% ± 6% v 16% ± 3% v 13% ± 4%, eccentric hypertrophy versus controls versus concentric hypertrophy, respectively, P = .04 for both eccentric versus concentric hypertrophy and for controls versus concentric hypertrophy). Conclusions Myocardial efficiency but not perfusion reserve is lower in hearts with concentric compared with eccentric left ventricular hypertrophy. This might be an explanation for the higher cardiovascular morbidity and mortality associated with concentric left ventricular hypertrophy.
Testicular Autotransplantation: A 17-Year Review of an Effective Approach to the Management of the Intra-Abdominal Testis

AbstractPurpose: Patients with intra-abdominal testes represent a small but challenging group who require innovative therapy. We report our 17-year experience with testicular autotransplantation.Materials and Methods: Testicular autotransplantation was performed in 23 patients with 27 intra-abdominal testes.Results: The success rate was 96 percent and average operative time was 4.25 hours with 40 to 90 minutes for vascular anastomoses. A contralateral Fowler-Stephens procedure had previously failed in 3 cases.Conclusions: Since the variability of collateral blood supply in patients with high undescended testes may potentially compromise the Fowler-Stephens procedure, we believe that testicular autotransplantation should be strongly considered in such patients, particularly those with bilateral undescended testicles.
Quinol Stimulation and Quinone Deterrency of Gustation by Scolytus multistrialus (Coleoptera: Scolytidae)

Mean feeding by the smaller European elm bark beetle, S. multistriatus (Marsham), in 48 hours increased linearly with the log of the concentration of p -hydroquinone per milliliter of solvent in which assay discs were treated. The oxidized product from p -hydroquinone, p benzoquinone, alone, failed to stimulate beetle feeding; and reduced (deterred) feeding stimulation by p -hydroquinone when added (in several concentrations) to a solution of the latter chemical. Several p -naphthoquinones also reduced the feeding stimulation of a given concentration of p -hydroquinone when added to the latter solution.
A capacity enhancement technique for multiple-access direct-sequence spread spectrum systems

In this paper a novel approach is presented that provides for a significant increase in the number of users in multi-user direct-sequence spread spectrum (DSSS) systems. This technique is based on division of the DSSS channel into a number of overlapping equal bandwidth sub-channels. It is shown that this division yields an increase in the number of users by 41% when the number of sub-channels is 11. The analysis is confirmed by means of a computer simulation.
A 10 kW IRFEL design for Jefferson Lab

Recent work at Jefferson Lab has demonstrated the viability of same-cell energy recovery as a basis for a high average power free-electron laser (FEL). We are now extending this technique to lase at average powers in excess of 10 kW in the infrared. This upgrade will also produce over 1 kW in the UV and generate high brightness Thomson back-scattered X-rays. The power increase will be achieved by increasing the electron beam energy by a factor of four, and the beam current and the FEL design efficiency by a factor of two. Utilization of a near-concentric optical cavity is enabled by the use of very low loss state-of-the-art coatings. The FEL will be placed in the return leg of the electron beam transport, giving a machine footprint quite similar to that of the existing 1 kW IR device. Some features of the upgrade are straightforward extensions of those in the present 1 kW design; others break new ground and present new challenges. These will be described. The required electron beam parameters and the laser performance estimates will be summarized. Changes required in the electron beam transport will be outlined and the optical cavity design briefly reviewed.
GPS C/N/sub 0/ estimation in the presence of interference and limited quantization levels

The carrier-to-noise density ratio (C/N0) is considered an important parameter describing the GPS receiver performance. This paper compares the performance of two popular coarse-acquisition (C/A) C/N0 algorithms appearing in literature: the variance summing method (VSM) (Psiaki et al., 2003, Psiaki, 2001), and the power ratio method (PRM) (Van Dierendonck, 1996, Sayre, 2003), in terms of their estimates in 1) additive white Gaussian noise (AWGN), 2) narrowband continuous wave interference (CWI), 3) their response to quantization and saturation effects, and their 4) dynamic range. The algorithms were implemented as a part of a software receiver. Two LI GPS data sets are examined; one was obtained from a GPS raw data collection setup, while the other was obtained from a GPS signal simulator. The collected set was stored with almost constant C/N0 level while the simulated one contained variable C/N0 levels. The effect of adding AWGN on the C/N0 estimate was directly proportional with the noise power. The C/N0 estimates suffered more when the CWI frequency was closer to the IF of the receiver. The PRM suffered from saturation at higher C/N0 levels. The VSM showed good tracking at high C/N0 levels and better immunity to limited quantization levels, while its C/N0 estimate suffered from rapid fluctuations in power levels when sudden power steps occurred
Totally Self-Checking Checker for 1-out-of-n Code Using Two-Rail Codes

A new design for a totally self-checking 1-out-of-n checker is presented. A comparison with other existing methods [1], [10] is given. It is shown that for many practical values of n the new scheme requires less hardware and/or is faster than the other methods. The entire checker can be tested by applying all of the n possible 1-out-of-n inputs.
SDF-1/CXCL12 induces directional cell migration and spontaneous metastasis via a CXCR4/Gαi/mTORC1 axis

Multiple human malignancies rely on C-X-C motif chemokine receptor type 4 (CXCR4) and its ligand, SDF-1/CXCL12 (stroma cell-derived factor 1/C-X-C motif chemokine 12), to metastasize. CXCR4 inhibitors promote the mobilization of bone marrow stem cells, limiting their clinical application for metastasis prevention. We investigated the CXCR4-initiated signaling circuitry to identify new potential therapeutic targets. We used HeLa human cancer cells expressing high levels of CXCR4 endogenously. We found that CXCL12 promotes their migration in Boyden chamber assays and single cell tracking. CXCL12 activated mTOR (mechanistic target of rapamycin) potently in a pertussis-sensitive fashion. Inhibition of mTOR complex 1 (mTORC1) by rapamycin [drug concentration causing 50% inhibition (IC50) = 5 nM] and mTORC1/mTORC2 by Torin2 (IC50 = 6 nM), or by knocking down key mTORC1/2 components, Raptor and Rictor, respectively, decreased directional cell migration toward CXCL12. We developed a CXCR4-mediated spontaneous metastasis model by implanting HeLa cells in the tongue of SCID-NOD mice, in which 80% of the animals develop lymph node metastasis. It is surprising that mTORC1 disruption by Raptor knockdown was sufficient to reduce tumor growth by 60% and spontaneous metastasis by 72%, which were nearly abolished by rapamycin. In contrast, disrupting mTORC2 had no effect in tumor growth or metastasis compared with control short hairpin RNAs. These data suggest that mTORC1 may represent a suitable therapeutic target in human malignancies using CXCR4 for their metastatic spread. .
The cost of modern technology

Continuous infusion of intravenous (i.v.) drugs is increasing in popularity, as technological advances in equipment (such as "smart" pumps) and pharmacologic improvements of drugs (such as ultra-short acting drugs) are introduced into clinical anesthesia practice. Such new technology, however, also introduces potential new complications. We report one such complication associated with the improper manufacturing of a proprietary i.v. tubing and cassette system.
Dating the Penninic Ocean subduction: new data from planktonic foraminifera

The Penninic Ocean was a side tract of the Central Atlantic Oceanic System intercalated between the European and the Austroalpine plates. Its closure started in the Early Cretaceous, as subduction of the oceanic crust beyond the Austroalpine plate. The sedimentary change on the Austroalpine shelf from pelagic carbonates into deep-water siliciclastics correlated with the denudation of the accretionary wedge resulting from that subduction. Within the Bajuvaric Unit of the Upper Austroalpine, this transition is reflected by the lithostratigraphic boundary between the older Schrambach and the younger Tannheim Formation. This boundary is well exposed in a newly discovered site at Sittendorf, southwest of Vienna. This new outcrop yields an extraordinarily rich planktonic foraminifera assemblage characterized by typical Aptian species belonging to Blowiella, Globigerinelloides, Hedbergella, Leupoldina, and Praehedbergella. A detailed biostratigraphic analysis based on thin-section investigations precisely dated the lithostratigraphic boundary within the lower part of the early Aptian Leupoldina cabri Acme Zone, having an approximate age of 123 Ma. Along with the biostratigraphic analyses, the gamma-log outcrop measurement was a powerful tool in interpreting the stratigraphy and the tectonic setting in the outcrop, which intersects one smaller-scale isoclinal fold.
Polyacrylamide-treated kaolin: A fabric study

Abstract Particle interactions, and in turn fabric, determine the behavior of clay mineral particle systems. Polymers with deliberately chosen characteristics, such as molecular mass and ionic type, can be utilized to manipulate clay fabric. The purpose of this study is to understand fabric development in a clay–polymer system, specifically kaolin–polyacrylamide systems over a wide range of solids content. Methodologies include sedimentation tests (low solids content), viscosity measurements (moderate solids content), and liquid limit measurements (high solids content), and are conducted to determine variation in fabric for kaolin–polyacrylamide systems at various concentrations, molecular mass and ionic types of polyacrylamide. Fabric development is verified using scanning electron microscopy (SEM). Results show that the polymer charge type impacts the resulting fabric formation only at polymer concentrations above a threshold concentration. Floc/aggregate size and density tend to increase with increasing polyacrylamide concentration, while high molecular-mass polyacrylamides tend to induce the formation of open flocculated structure. The most likely particle association in the presence of nonionic polyacrylamides is face-to-face association due to polymer bridging. A relationship is found between polymer characteristics, solids contents, and micro-scale particle arrangement. This study is relevant to the emerging field of engineered soil fabrics.
Inferring word meanings by assuming that speakers are informative

Language comprehension is more than a process of decoding the literal meaning of a speaker's utterance. Instead, by making the assumption that speakers choose their words to be informative in context, listeners routinely make pragmatic inferences that go beyond the linguistic data. If language learners make these same assumptions, they should be able to infer word meanings in otherwise ambiguous situations. We use probabilistic tools to formalize these kinds of informativeness inferences-extending a model of pragmatic language comprehension to the acquisition setting-and present four experiments whose data suggest that preschool children can use informativeness to infer word meanings and that adult judgments track quantitatively with informativeness.
A Retrospective Comparison of Ceftriaxone Versus Oxacillin for Osteoarticular Infections Due to Methicillin-Susceptible Staphylococcus aureus

Staphylococcus aureus is the most frequent organism isolated in osteoarticular infections [1]. The treatment options for S. aureus infections depend on the resistance pattern of the isolate. For methicillin-sensitive S. aureus (MSSA) infections, the drugs of choice are the antistaphylococcal penicillins (oxacillin, nafcillin, and methicillin) [2]. Few studies have compared the standard antistaphylococcal penicillins to newer β-lactam antibiotics such as cephalosporins. Ceftriaxone, a third-generation, long-acting, intravenous cephalosporin, has been shown to be an effective treatment for MSSA infections in general [3, 4]. There are limited data supporting the use of ceftriaxone for the treatment of osteoarticular infections due to MSSA [5], although its bone penetration is similar to that of penicillins [6]. Ceftriaxone is attractive for treatment of bone and joint infections for a number of reasons. It is well tolerated [7] and given once daily, whereas oxacillin is given either 6 times per day or via continuous infusion. Once-daily dosing may improve patients’ adherence to outpatient antibiotic therapy [8]. Also, it is comparatively inexpensive [9]. Because osteoarticular infections require prolonged intravenous treatment courses of at least 4–6 weeks, tolerability, convenience, and cost are important considerations in the antibiotic choice [10]. To our knowledge, there has never been a direct comparison of clinical outcomes in MSSA osteoarticular infections treated with ceftriaxone versus antistaphylococcal penicillins. Our study sought to retrospectively compare treatment outcomes of MSSA osteoarticular infections treated with ceftriaxone versus oxacillin at our institution. We hypothesized that rates of clinical treatment success after 3 and 6 months following the completion of intravenous antibiotics would be similar irrespective of the treatment group. A secondary goal was to compare the tolerability of the 2 medications and the frequency of treatment modifications due to antibiotic toxicity.
Piloting with celestial algorithms

This paper shows how coastal piloting observations can be cast in a form that allows them to be reduced using a celestial navigation algorithm. This is useful when navigating with a computer that can compute a position fix from celestial observations, but is not explicitly designed to handle coastal piloting. It is also a useful technique for incorporating piloting into a computer program without programming piloting and celestial techniques separately. We treat three cases: a range to a known object, a bearing to a known object, and a horizontal angle measured between two known objects.
Is PAR a Good Investment? Understanding the Costs and Benefits of Teacher Peer Assistance and Review Programs

Peer Assistance and Review (PAR) is a local labor–management initiative designed to improve teacher quality. In PAR, expert “consulting teachers” mentor, support, and evaluate novice and underperfo...
Asymptotic behavior of nonlinear m-D digital filters with singularities on the distinguished boundary

The stability robustness of multidimensional digital filters with singularities on the distinguished boundary under the effect of finite wordlength is addressed. In particular, it is shown that all purely first-order digital filters with nonessential singularities of the second kind (NSSK) are asymptotically stable under certain types of nonlinearities. Even bounded-input bounded-output unstable multidimensional digital filters with singularities on the distinguished boundary are proved to be asymptotically stable in the first-order case. These results are then extended to certain classes of higher-order multidimensional digital filters. It is demonstrated that, although multidimensional digital filters with NSSKs on the distinguished boundary have no margin of linear stability, they might exhibit a rather robust behavior to nonideal effects such as finite wordlength. >
Optimization of on -State and Switching Performances for 15–20-kV 4H-SiC IGBTs

The 4H-SiC p-channel IGBTs designed to block 15 and 20 kV are optimized for minimum loss (on-state plus switching power) by adjusting the parameters of the JFET region, drift layer, and buffer layer, using 2-D MEDICI simulations. Switching loss exhibits a strong dependence on buffer layer thickness, doping, and lifetime due to their influence on the current tail. In contrast, drift layer lifetime has little effect on the crossover frequency at which the MOSFET and IGBT have equal loss.
Future datacenter interfaces based on existing and emerging optics technologies

Mainstream datacenter interfaces use NRZ modulation, VCSEL or DFB lasers, parallel or WDM channels, packaged in pluggable modules. Emerging technologies are higher order modulation, faster lane rate, InP or Si modulator (Si Mod), and board mounted optics. Future datacenter interfaces will use all of these to increase link rates.
Major element heterogeneity in the mantle source of the North Atlantic igneous province

High-MgO (s 8.5 wt%), aphyric lavas erupted at various locations in the North Atlantic igneous province are utilized to characterize the nature of mantle melting during the formation of this province. Based on the observation that the Ni concentration in residual mantle olivine mostly falls in the range of 2000^3500 ppm, these high-MgO samples are corrected for olivine fractionation until the Ni concentration of equilibrium olivine reaches 3500 ppm, to estimate the composition of primary mantle-derived melt. Estimated primary melt compositions suggest that this province is characterized by significant major element source heterogeneity possibly resulting from basalt addition prior to melting. Primary melts for Southwest Iceland and Theistareykir (North Iceland) are shown to require different source mantle compositions. Whereas the Theistareykir primary melt may be explained by the melting of pyrolitic mantle, the source mantle for Southwest Iceland must be enriched in iron, having molar Mg/(Mg+Fe), or Mg#, 6 0.88. This compositional dichotomy in Iceland seems to continue to adjacent Mid-Atlantic Ridge segments, i.e. the Kolbeinsey and Reykjanes Ridges. The primary melts for East and Southeast Greenland also indicate a fertile mantle source, and the estimate of Mg# is the lowest for the East Greenland source mantle (6 0.87). The inferred spatial extent of source heterogeneity suggests the presence of a long-lived compositional anomaly in this igneous province since the opening of the North Atlantic. fl 2000 Elsevier Science B.V. All rights reserved.