cssi/SciSciGPT-SciSciNet huggingface dataset:
3D printed, mechanically tunable, composite sodium alginate, gelatin and Gum Arabic (SA-GEL-GA) scaffolds

Abstract Biomimicking the mechanical properties of native tissues is one of the key requirements of engineering tissue scaffolds, rendering a need for materials and manufacturing processes with a high level of control over the mechanical properties of such scaffolds. To address this need, we present a 3D printable, composite hydrogel consisting of sodium alginate (SA), gelatin (GEL) and gum Arabic (GA), referred to herein as SA-GEL-GA hydrogel, mechanical properties of which can be controlled through tuning its cross-linking process. Here, the aqueous solution of the three constituents is used as the bioink to 3D print porous scaffolds in a temperature-controlled extrusion-based printing process. 3D-printed scaffolds are then crosslinked through a multi-step approach, realizing the gelation of GEL, ionic crosslinking of SA and GA, and covalent cross-linking of all three components. Here, we show that the inherent mechanical properties of SA-GEL-GA hydrogels can be controlled through the duration of the covalent crosslinking step. SA-GEL-GA bioinks exhibit highly temperature-dependent rheology with elastic solid-like behavior below room temperature and a viscoplastic, shear thinning nature above 28 ​°C. Using a cooled build-plate and heated printhead, high resolution scaffolds were printed with filament diameter of 250 ​μm and extruded from a 100 ​μm diameter nozzle. The compressive elastic modulus of these scaffolds can be tuned to the 50–250 ​kPa range through the combined effect of the scaffold pores size and covalent crosslinking step duration. 3D printed and crosslinked scaffolds carry over 500% of their dry weight in water and can be dried and reswollen to over 400% of their dry weight. Finally, our degradation analysis showed that increased covalent cross-linking duration led to reduced long-term structural stability due to mechanical failure of the scaffolds. These results indicate that SA-GEL-GA hydrogels offer exciting opportunities for manufacturing customizable artificial tissue scaffolds with biomimicking mechanical properties, particularly for soft tissues.
Tourism and the Transformation of Daily Life Along the Riviera Maya of Quintana Roo, Mexico

Resumen En el espacio de menos de dos decadas, los habitantes de Quintana Roo han tenido que enfrentar cambios radicales ocasionados por el turismo de masas. El turismo se ha convertido en la industria dominante y esto ha puesto en marcha un ciclo de desarrollo turistico y de migracion masiva de otras partes de Mexico y del exterior. Una region que no hace mucho tiempo se consideraba el territorio mas marginal de la nacion, hoy atrae millones de turistas de todo el mundo, la mayoria de los Estados Unidos y Europa. En un contexto de cambio acelerado y control empresarial, la vida de muchas personas, incluso la poblacion maya, es altamente imprevisible y estresante. La expansion del turismo se ha desplazado recientemente a Tulum, una ciudad que esta emergiendo como una localidad de pequenos, pero bien comodos, hoteles.
Fault Tolerant Wide-Area Parallel Computing

Executing parallel applications across distributed networks introduces the problem of fault tolerance. A viable solution for fault tolerance must keep overhead manageable and not compromise the high performance objective of parallel processing. In this paper, we explore two options for achieving fault tolerance for a common class of parallel applications, single-program-multiple-data (SPMD). We quantitatively compare checkpoint-recovery and wide-area replication as a means of achieving fault tolerance. The experimental results obtained for a canonical SPMD application suggest that checkpoint-recovery may be preferable for small problems if local parallel disks are available, but wide-area replication outperforms checkpoint-recovery for larger-grain problems, precisely the problems most suited for the wide-area network environment. The results also show that it possible to accurately model and predict the overheads of the two methods
Object conveyance control algorithms with spatially changeable end target location using Large-Scale Actuator Networks

A class of robotic systems that is attracting increased scientific attention is Large-Scale Actuator Networks (LSANs). A potential application of actuator networks is distributed manipulation, a technique that has significant utility within the field of industrial automation. A reactive elastic surface that autonomously morphs its shape to transport an arbitrary number of objects to a target location is presented to explore this class of systems. A collection of actuators within a network are used to overcome the limitations of individual actuator elements, and results in a system that has multiple degrees-of-freedom. Experimental results and simulation data are presented to illustrate the functionality and scalability of the platform.
The Demise of the Waterfall Model Is Imminent, and Other Urban Myths: Rumors of the demise of the Waterfall Life-cycle Model are greatly exaggerated.

We discovered this and other disappointing indicators about current software engineering practices in a recent survey of almost 200 software professionals. These discoveries raise questions about perception versus reality with respect to the nature of software engineers, software engineering practice, and the industry.
Return to competition, re-injury, and impact on performance of preseason shoulder injuries in Major League Baseball pitchers

AbstractObjective: Major league baseball (MLB) pitchers are vulnerable to overuse injury of the upper extremity, especially in the shoulder. Injuries sustained in the preseason may have negative impact on performance following return. The goal of this study was to document the frequency of preseason shoulder injury in these athletes, as well as risk for re-injury and impact on performance following return from injury. Methods: A comprehensive search of MLB injury information from 2001 to 2010 of public databases yielded a cohort of MLB pitchers who sustained preseason shoulder injuries. These databases were utilized to obtain information regarding return to MLB competition, re-injury, and performance following return from injury. All performance metrics were compared to those of an age-matched control cohort. Results: A total of 74 pitchers were identified who sustained a preseason shoulder injury. Only 39 (53%) returned that same season to pitch in the MLB competition. Of those that returned, nearly 50% ...
On the QCD corrections to b → sγ in supersymmetric models☆

Abstract We reinvestigate the leading QCD corrections to the radiative decay b → sγ for supersymmetric extensions of the Standard Model. Although the major contributions to the corrections originate from the running of the effective Lagrangian from the W scale down to the b scale, additional corrections are expected from large mass between the particles running in the loops, as well as from integrating out heavy particles at scales different from the W mass. The calculation is performed in the framework of effective field theories.
SUPERSYMMETRIC SIGNALS AT THE TEVATRON

The possibility of detecting SUSY signals arising from Wino and Zino production at the Tevatron is examined. If the Tevatron is operated at peak luminosity of 1031cm−2sec−1 with full lepton detection capabilities, we estimate for a UA1 type apparatus that the trilepton signal is sensitive to Winos with mass up to ≈70–80 GeV, the dilepton signal up to ≈50–60 GeV and the monojet signal up to ≈45–50 GeV.
First‐mover advantages

The use of a fairly standard vehicle width of a little under 2 meters originates from the design of prehistoric carts and sleds as evidenced by rutting in ancient roads which aided in steering. Despite dramatic advances in vehicular and infrastructural technologies, the standard has changed little over the millennia. The gauges of railroad track, for instance, are now standardized at 4 feet 8 and half inches (1435 mm) across Europe and North America, the same as the first steam railway, and a mere half-inch wider than the typical pre-steam tracks in the mining districts near Newcastle, consistent in size with the wheel gauge used in Roman Britain. This standard gauge lasted since it was first used on the Stockton and Darlington railway in 1825, and were adopted by most subsequent lines (Puffert, 2002), despite some railways trying alternatives (e.g. the Great Western Railway was originally built at 5 feet 6 inches, or 1676 mm). Alternative gauges would have accommodated wider, taller, and faster trains more easily, but the standard gauge that was adopted first acquired advantages as other railways sought compatibility with the standard to obtain access to the uses of earlier lines, and helped lock-in that standard.
E. coli L-asparaginase and insulin release in vitro

Abstract Glucose induced insulin release, from collagenase isolated islets of Langerhans obtained from non diabetic male New Zealand White rabbits, was inhibited in vitro by E. coli L-asparaginase. This inhibition was time and dose dependent with maximal inhibition being attained after 1 1 2 hr incubation using a dose of 1000 I.U. L-asparaginase/ml. Tolbutamide potentiated glucose-induced insulin release in the presence of inhibitory doses of the L-asparaginase. This potentiation was decreased at higher dose levels of L-asparaginase. L-leucine, L-arginine and theophylline also potentiated glucose-induced insulin release in the presence of L-asparaginase. This potentiation was intact in the presence of all doses of L-asparaginase tested. Glucose induced insulin release, from collagense isolated islets obtained from male New Zealand White rabbits rendered hypoinsulinemic and diabetic by daily intravenous injections of L-asparaginase in vivo, was similar to that of islets of non diabetic control rabbits when the islets were incubated in vitro in the absence of L-asparaginase. These data suggest that the hypoinsulinemic diabetic syndrome produced by the anti-tumor enzyme, L-asparaginase, is produced at least in part by the suppression of insulin release and that this suppression requires the enzyme to be present.
Correlated time derivatives of current, electric field intensity, and magnetic flux density for triggered lightning at 15 m

[1] We present measured current and its time derivative correlated with the corresponding electric field intensity and magnetic flux density and their time derivatives measured at 15 m for two lightning return strokes triggered in 1999 at Camp Blanding, Florida. Lightning was triggered to a vertical 2-m rod mounted at the center of a 70 × 70 m buried metallic grid. The rocket-launching system was located underground at the center of the grid. The experiment was designed to minimize any influence of either the strike object or a finite-conducting Earth (ground surface arcing and propagation effects) on the fields and field derivatives. The measured current derivative waveform and the return stroke portion of the magnetic flux density derivative and electric field intensity derivative waveforms associated with the two strokes are observed to be essentially unipolar pulses that have similar waveshapes for the first 150 ns or so, including the initial rising portion, the peak, and about 50 ns after the peak. The current and magnetic field derivative waveshapes are very similar for their total duration, and both decay to near zero about 200 ns after the peak derivative is reached. The electric field derivative decays more slowly than the current derivative after about 150 ns, taking about 500 ns to decay to near zero. The transmission-line model, the simplest available and most used return stroke model, is employed to calculate the return stroke field derivatives, given the measured current derivative as a model input, for return stroke speeds of 1 × 108 m s−1, 2 × 108 m s−1, and 3 × 108 m s−1 (the speed of light). A reasonable match between calculated and measured field derivative waveshapes is achieved for both strokes for a return stroke speed between 2 × 108 m s−1 and 3 × 108 m s−1. Although the measured field and current derivatives have similar waveshapes for about 150 ns, which might appear to be consistent with the hypothesis that the radiation field component of the total field derivative is dominant for that time, transmission line model calculations indicate that this is not the case. Further, electric field derivatives measured simultaneously at 15 m and at 30 m for many strokes are observed to have similar waveshapes, which also might appear to be consistent with the hypothesis that the derivatives are dominated by the radiation field component; however, according to transmission line model calculations, while the calculated total field derivative waveshapes are similar at 15 and 30 m, all field components significantly contribute to the waveforms at both distances, and the mix of field components at 15 m and at 30 m is quite different.
Assessing Release-Time Options in a Two-Channel AGC Hearing Aid

The purpose of this study was to determine whether different release times, as implemented in a commercial two-channel AGC hearing aid, would result in differing speech intelligibility performance,...
Evaluation of the precordial leads of the electrocardiogram in obesity

Abstract Obesity is often associated with a Q wave and inversion of T in standard Lead III, changes which may simulate myocardial involvement and posterior infarction. The present investigation was undertaken to determine whether significant changes occurred in the chest leads. In obesity the amplitude of the precordial T wave, as measured in the unipolar (V) leads, is reduced to 50 per cent of normal. However, the T wave was not inverted in the V leads recorded in Positions 2 through 6. The extremity influences may be great enough to produce significant distortion of the T wave in CF and CL leads. In these leads the T wave was inverted in leads made in Positions 2 and 3 in 20 per cent of the cases of our series, and in leads made in Positions 4, 5, and 6 in 10 to 15 per cent. An inverted T wave in the CF and CL leads obtained from obese subjects is not abnormal. The CR leads show distortion in the direction of normality. This is useful in obesity but may mask T-wave alteration in abnormal conditions. The diminished height of the precordial T wave in obese subjects is probably the result of elevation of the diaphragm. In support of this view, a case of ascites with T-wave changes in the CF leads is described in which the T waves became normal following paracentesis. The unipolar chest (V) leads should be employed routinely since they are probably more reliable than the CF, CL, and CR leads.
Status of the Advanced Photon Source low-energy undulator test line

Abstract A Low-Energy Undulator Test Line (LEUTL) is under construction at the Advanced Photon Source (APS). Its purpose is to fully characterize innovative, future-generation undulators, and to act as a test line in pursuit of generating coherent radiation at wavelengths down to a few tens of nanometers. The line will use a high-brightness RF electron gun as its source and the APS linac to accelerate these electrons up to >650 MeV. This beam will then be directed through undulators located in a new 50 m long enclosure. In addition, there is an end station external to the radiation environment which will house the equipment necessary to directly study the light generated by the beam and undulator system. At present, the new enclosures are complete, the electron rf gun is installed and operational, and a part of the necessary transport line is installed. A prototypical undulator cell, suitable for testing the requirements of single-pass free-electron laser operation, is near completion and will be installed during the winter shutdown of 1998. This paper will describe the LEUTL project and, in particular, its capabilities for exploring the self-amplified spontaneous emission process.
Growth and transport properties of Sb2-xVxTe3 thin films on sapphire substrates

Abstract Thin films of Sb 2− x V x Te 3 with x = 0 , 0.15, 0.32 and 0.35 have been grown on sapphire (0 0 0 1) substrates using molecular-beam epitaxy. With the increasing concentration of vanadium, the in-plane lattice constant of Sb 2− x V x Te 3 films decreases while the c -axis lattice constant shows a very small increase. The electrical resistivity of Sb 2− x V x Te 3 films decreases by an order of magnitude when V is substituted on the Sb sublattice. The Hall effect measurements show an increase in the concentration of holes as the content of vanadium increases.
WS13‐04Doppler velocimetry determined brain sparing effect: correlations with neonatal outcome in diamniotic monochorionic and diamniotic dichorionic twins

Objective Neonatal outcome was studied in 169 infants from diamniotic monochorionic (DAMC) and diamniotic dichorionic (DADC) twin pregnancies in relation to a measure of blood flow redistribution, the cerebroplacental ratio (CPR). Study design Two groups were assessed, 50 infants from DAMC, and 119 infants from DADC twin pregnancies. Targeted ultrasound and Doppler recordings of umbilical artery (UA) and middle cerebral artery (MCA) were obtained. The resistance index (RI) and CPR were calculated for each fetus. Results DAMC twins had lower birth weight (1979 vs. 2223 g for DADC, p≤.01) and prolonged lengths of nicu stay (8.5 days vs. 3.5 days for DADC, p≤.05). For total group, DAMC compared with DADC twins spent greater numbers of days on a ventilator. SGA infants were significantly more frequent in DAMC twins compared to DADC twins. Among antenatal Doppler variables only the CPR demonstrated a significant difference between twin types. For DAMC twins CPR was 1.15 vs. 1.21 for DADC twins, p≤.05. Conclusions Monochorionic twins from the lower birth weight groups demonstrate a greater number of growth restricted infants and prolonged hospitalizations compared to DADC twins. Among Doppler measures, the CPR is superior to UA-RI, and/or MCA-RI for the prediction of adverse events.
Aboveground decomposition dynamics in riparian depression and slope wetlands of central Pennsylvania

We examined two types of groundwater-fed wetlands (riparian depressions and slopes) classified using the hydrogeomorphic (HGM) system. These wetland types had previously been shown to differ hydrologically. Our first objective was to determine if HGM was a useful structuring variable when examining aboveground decomposition dynamics (rate of mass loss and rate of nitrogen loss). Our second objective was to determine what soil variables were related to any differences in aboveground decomposition dynamics we might find regardless of HGM subclass. We used the litterbag field bioassay technique, and employed a standard litter type (Phalaris arundinacea) across all wetlands. Our results indicated that HGM would not readily serve as an adequate structuring variable for aboveground decomposition in riparian depressions and slope wetlands of central Pennsylvania. Discriminant analysis and classification and regression tree (CART) modeling found soil cation exchange capacity, soil pH, soil organic matter, and soil % nitrogen to be potentially important soil variables related to mass loss, and soil % nitrogen and soil pH to be potentially important variables related to nitrogen loss rate.
Evaluating subject-level incremental values of new markers for risk classification rule

Suppose that we need to classify a population of subjects into several well-defined ordered risk categories for disease prevention or management with their “baseline” risk factors/markers. In this article, we present a systematic approach to identify subjects using their conventional risk factors/markers who would benefit from a new set of risk markers for more accurate classification. Specifically for each subgroup of individuals with the same conventional risk estimate, we present inference procedures for the reclassification and the corresponding correct re-categorization rates with the new markers. We then apply these new tools to analyze the data from the Cardiovascular Health Study sponsored by the US National Heart, Lung, and Blood Institute. We used Framingham risk factors plus the information of baseline anti-hypertensive drug usage to identify adult American women who may benefit from the measurement of a new blood biomarker, CRP, for better risk classification in order to intensify prevention of coronary heart disease for the subsequent 10 years.
Influence of intranasal cocaine on plasma constituents associated with endogenous thrombosis and thrombolysis

Abstract purpose: As cocaine abuse has become widespread, catastrophic cocaine-associated cardiovascular events have been noted with increasing frequency. Although these incidents are thought to be caused by drug-induced vasoconstriction and/or arterial thrombosis, the influence of cocaine on the plasma constituents involved in endogenous thrombosis and thrombolysis has not been characterized. patients and methods: In 22 patients (8 men, 14 women, ages 32 to 62 years) undergoing cardiac catheterization, blood samples were procured before and 15 minutes after the administration of intranasal saline (n = 8, controls) or cocaine, 2 mg/kg (n = 14), and the plasma concentrations of fibrinogen, plasminogen, and lipoprotein(a), as well as tissue plasminogen activator activity and plasminogen activator inhibitor (PAI-1) activity, were measured. results: No variable changed with the use of intranasal saline, whereas the use of cocaine resulted in an increase in PAI-1 activity (0.48 + 0.06 [mean + SD] nmol/L at baseline, 0.53 + 0.05 nmol/L after cocaine, P = 0.011). conclusion: Intranasal cocaine administration is associated with an increase in plasma PAI-1 activity. This may be important in recreational users of cocaine who experience vascular thrombosis.
Approximants to the nuclear-spin autocorrelation function. Application to Ca F 2

A simple method for generating approximants to the nuclear-spin autocorrelation function from the known moments is described. Expressions for the two lowest-order approximants are derived and the numerical results are compared with the $^{19}\mathrm{F}$ experimental free-induction-decay signals in Ca${\mathrm{F}}_{2}$.
In vivo noninvasive monitoring of a tissue engineered construct using 1H NMR spectroscopy

Direct, noninvasive monitoring of tissue engineered substitutes containing live, functional cells would provide valuable information on dynamic changes that occur postimplantation. Such changes include remodeling both within the construct and at the interface of the implant with the surrounding host tissue, and may result in changes in the number of viable cells in the construct. This study investigated the use of 1H NMR spectroscopy in noninvasively monitoring the viable cell number within a tissue engineered construct in vivo. The construct consisted of mouse betaTC3 insulinomas in a disk-shaped agarose gel, surrounded by a cell-free agarose gel layer. Localized 1H NMR spectra were acquired from within implanted constructs, and the total choline resonance was measured. Critical issues that had to be addressed in accurately quantifying total choline from the implanted cells included avoiding signal from host tissue and correcting for interfering signal from diffusing solutes. In vivo NMR measurements were correlated with MTT assays and NMR measurements performed in vitro on explanted constructs. Total choline measurements accurately and noninvasively quantified viable betaTC3 cell numbers in vivo, in the range of 1 x 10(6) to more than 14 x 10(6) cells, and monitored changes in viable cell number that occurred in the same construct over time. This is the first study using NMR techniques to monitor viable cell numbers in an implanted tissue substitute. It established architectural characteristics that a construct should have to be amenable to NMR monitoring, and it set the foundation for future in vivo investigations with other tissue engineered implants.
Prophylactic Fresh Frozen Plasma Infusion is Ineffective in Reversing Warfarin Anticoagulation and Preventing Delayed Intracranial Hemorrhage After Falls.

Elderly patients, with considerable fall risk, are increasingly anticoagulated to prevent thromboembolic disease. We hypothesized that a policy of prophylactic fresh frozen plasma (FFP) infusion in patients having falls would reverse vitamin K antagonists (VKAs) and that reversal would decrease delayed intracranial hemorrhage (ICH).A retrospective review of patients with trauma admitted to a level 2 community trauma center was performed from January 2010 until November 2012. Inclusion criteria were: ground level fall (GLF) with suspected head trauma, on VKA, an international normalized ratio (INR) of >1.5, and a negative head computed tomography (CT). Patients were transfused with FFP to a goal INR of 1.5. Chi-square and logistic regression were performed.A total of 194 patients met the criteria. In all, 43 (22%) patients were able to be REV, and 151 (78%) patients remained NREV. Unreversed patients were male and younger (P < .05). There was no difference in mean FFP received. Unreversed patients had a higher initial INR of 3.0 compared to REV patients (2.5; P = .018). One patient developed a delayed ICH and belonged to the REV group.The incidence of delayed hemorrhage was 0.5%. A strategy of prophylactic FFP infusion was ineffective in VKA reversal. We recommend against prophylactic infusion of FFP during a period of observation for patients on VKA with suspected head trauma and a negative initial CT.
Regulation of hypothalamic and pituitary corticotropin-releasing hormone receptor messenger ribonucleic acid by adrenalectomy and glucocorticoids

The effects of adrenalectomy and glucocorticoids on the regulation of corticotropin-releasing hormone (CRH) receptor expression in the hypothalamic paraventricular nucleus (PVN) and pituitary were studied by in situ hybridization in the rat using a complementary RNA probe directed toward the coding region of the type 1 CRH receptor. Eighteen hours after adrenalectomy, CRH receptor messenger RNA (mRNA) expression in the PVN was significantly increased, whereas longer term adrenalectomy (4 and 6 days) had no effect. This transient effect of adrenalectomy was prevented by glucocorticoid replacement. In intact rats, 4 h after immobilization for 1 h or a single ip hypertonic saline injection, CRH receptor mRNA in the PVN markedly increased (P < 0.01), an effect that was unchanged by adrenalectomy (4 or 6 days) or dexamethasone injection (100 micrograms at -14 and 50 micrograms at -1 h) before stress. In the pituitary, CRH receptor mRNA levels decreased transiently after adrenalectomy (-62% after 18 h), returning to basal levels 4 or 6 days after adrenalectomy. The early decrease was prevented by glucocorticoid replacement. In intact rats, dexamethasone (100 micrograms, sc) caused a significant decrease in pituitary CRH receptor mRNA levels 2-10 h after injection, returning to basal levels after 15 h. On the other hand, dexamethasone (5-300 micrograms, sc) had no effect on pituitary CRH receptor mRNA levels 18 h after injection. The data show that although stress stimulation of CRH mRNA in the PVN is glucocorticoid independent, basal levels are likely to be under dual, transcriptional and posttranscriptional, control by glucocorticoids. In the pituitary, changes in hypothalamic CRFs probably play a major role in the control of CRH receptor mRNA levels during manipulations of circulating glucocorticoids levels. In addition, the inability of long term adrenalectomy and glucocorticoid administration to modify pituitary CRH receptor mRNA levels suggests that CRH receptor down-regulation observed under these experimental conditions depends mainly on translational and post-translational events rather than receptor mRNA levels.
Biocompatibility of Delrin 150: A creep‐resistant polymer for total joint prostheses

A thermoplastic polymer, Delrin 150 (polyoxymethylene homopolymer), with creep resistance ten times that of ultrahigh-molecular-weight polyethylene, is used as a material for total joint prostheses. A study was made of the local and systemic host response to this polymer when implanted in three different mammalian species. 316 LC stainless steel was used as a control. The materials were implanted into muscle and bone as solid cylinders. A total of 446 samples were implanted into 74 animals. The duration of implantation ranged from 2 weeks to 2 years. A semi-quantitative evaluation of local tissue reaction was performed. For each implant, 16 histological criteria were graded for severity of host tissue reaction. The liver, spleen, kidneys, pancreas, and lungs from each animal were also studied for evidence of systemic toxicity. The polymer implants exhibited a mild tissue reaction with the same characteristics as the control. Local tumor formation, bone osteolysis, and surrounding muscle necrosis were not seen. No pathological changes compatible with systemic toxicity by Delrin 150 were observed in the study of the organs. Delrin 150 in solid form did not exhibit local or systemic toxicity and is therefore biocompatible by this study. Powder implantation studies should be performed to simulate tissue response to wear particles.
A physiological study of functional expression in Escherichia coli of the cloned yeast imidazoleglycerolphosphate dehydratase gene.

Abstract Functional expression in Escherichia coli of bacteriophage λ and plasmid hybrids containing the Saccharomyces cerevisiae (yeast) gene for imidazoleglycerolphosphate (IGP) dehydratase ( his3 ) has been characterized in growing E. coli cells lacking the bacterial IGP dehydratase activity and during lytic infection of these cells. his3 expression of an integrated bacteriophage λhis3 hybrid requires transcriptional initiation from a “promoter” in the yeast DNA. A deletion mutant lacking this promoter, but containing the his3 structural gene has been isolated. Fusion of a DNA segment containing this promoter to a segment containing the intact structural gene for tetracycline resistance ( tet r ) but lacking an intact promoter results in expression of the tet r gene. Using four physiological criteria, the level of his3 expression in growing E. coli cells is affected by gene dosage. By these criteria, cells containing multiple copies of the his3 gene produce nearly wild-type E. coli activity levels of yeast IGP dehydratase. There is no evidence for regulation of his3 expression at the gene level as a function of histidine starvation. Expression of the his3 gene during lytic infection by bacteriophage λ hybrids has been assessed by the ability of such hybrids to grow in histidine-starved E. coli cells lacking IGP dehydratase. Phage containing a functional his3 gene grow with a single burst of five under these conditions and also form “plaques without lawns” on the starved cells. Lytic expression depends on transcription from the λ promoter P L ; the level depends on the distance from P L to the his3 gene. The results indicate that expression in E. coli of a eukaryotic gene obeys prokaryotic rules of gene expression and that it can occur at a significantly high level. This suggests that the basic gene recognition signals of eukaryotes and prokaryotes may not be so different.
Fluency and eye contact as factors influencing observers' perceptions of stutterers

Abstract The purpose of this study was to determine the effects of different levels of eye contact and fluency on observers' perceptions of a speaker. One of four videotapes depicting an actor (playing the part of a supervisor) interviewing another actor (who played a subordinate) were shown to 127 college students. The four videotapes represented four different conditions comprising combinations of fluent vs nonfluent speech and normal vs low eye contact. Results indicated that these combinations of fluency and eye contact differentially influence listeners' perceptions of a speaker. Highest ratings were obtained for the fluent-normal eye-contact speaker, with lower ratings for all other conditions. In addition, it was determined that the frequency of eye contact rather than fluency was more strongly related to listeners' perceptions. The clinical implications of these findings are discussed.
Multilevel bioluminescence tomography based on radiative transfer equation Part 1: l1 regularization

In this paper we study an l1-regularized multilevel approach for bioluminescence tomography based on radiative transfer equation with the emphasis on improving imaging resolution and reducing computational time. Simulations are performed to validate that our algorithms are potential for efficient high-resolution imaging. Besides, we study and compare reconstructions with boundary angular-averaged data, boundary angular-resolved data and internal angular-averaged data respectively.
Confirmation and complete 1H and 13C NMR assignment of the structure of peptidoglycan from Sarcina ventriculi, a highly adaptable Gram-positive bacterium

Abstract The structure of peptidoglycan extracted from the Gram-positive bacterium Sarcina ventriculi grown at pH 3 was characterized by amino acid analysis, mass spectrometry, and two-dimensional NMR spectroscopy. The basic muropeptide subunit consisted of an N -acetylglucosamine- β -1,4- N -acetylmuramic acid disaccharide substituted with an oligopeptide with the sequence Ala- iso Gln-A 2 pm(-Gly)-Ala. The dimeric muropeptide was also characterized as a cross-linked bis-disaccharide-penta-hexapeptide with the structure, GlcNAc-MurNAc-Ala- iso Gln-A 2 pm(-Gly)-Ala → GlcNAc-MurNAc-Ala- iso Gln-A 2 (-Gly)-Ala-Ala. These results are consistent with a structure proposed based on enzymatic degradation and chemical modifications but with no use of spectroscopic information [O. Kandler, D. Claus, and A. Moore, Arch. Mikrobiol. , 82 (1972) 140–146]. The cell wall of this organism is very tightly cross-linked and is much more rigid than that of most other Gram-positive bacteria. There is, however, a large degree of conservation in the general structure compared to peptidoglycan in other bacteria that are not well adaptable to extremes, indicating that the membrane plays a more important role in adaptation.
Histochemical studies of developing human fetal small intestine

The histochemical characteristics of absorptive and mucus-producing cells have been described in 16 specimens of small intestine from human fetuses between 7 and 22 weeks of age. In the youngest specimens a slight to moderate reaction was found for all enzymes examined which included those known from biochemical or ultrastructural studies to be located predominantly in Golgi apparatus (thiamine pyrophosphatase), surface membrane (alkaline phosphatase, adenosine triphosphatase, leucine aminopeptidase), lysosomes (acid phosphatase), and mitochondria (succinic dehydrogenase). Mucus granules of somehat unusual location and staining properties were also found at this time. A progressive intensification of a majority of these histochemical reactions was observed between 3 and 6 fetal months.
Simultaneous electromagnetically induced transparency for two circularly polarized lasers coupled to the same linearly polarized laser in a four-level atomic system in the W scheme

Electromagnetic induced transparency (EIT) can be produced in a four-level atomic system in the W scheme using a linearly polarized optical field for simultaneously slowing down two $\ensuremath{\sigma}{}^{+}$ and $\ensuremath{\sigma}{}^{\ensuremath{-}}$ circularly polarized optical fields. This four-level atomic system can be set up with a $|{}^{1}{S}_{0}\ensuremath{\rangle}$ ground state and three Zeeman levels of the $|{}^{1}{P}_{1}\ensuremath{\rangle}$ excited state of any alkali-metal atom placed in a weak magnetic field. We apply our W scheme to ultracold magnesium atoms for neglecting the collisional dephasing. Atomic coherences are reported after solving a density matrix master equation including radiative relaxations from Zeeman states of the $|{}^{1}{P}_{1}\ensuremath{\rangle}$ multiplet to the $|{}^{1}{S}_{0}\ensuremath{\rangle}$ ground state. The EIT feature is analyzed using the transit time between the normal dispersive region and the EIT region. The evolution of the EIT feature with the variation of the coupling field is discussed using an intuitive dressed-state representation. We analyze the sensitivity of an EIT feature to pressure broadening of the excited Zeeman states.
Enhancement of staphylococcal virulence for mice by intraperitoneal cortisone acetate, cholesterol and lecithin.

THE intraperitoneal administration of bile salts and of certain surfactants, followed by an ordinarily non-lethal inoculum of micro-organisms belonging to a number of different species, results in marked enhancement of the virulence of the latter for mice as manifested by a high incidence of fatal bacteraemia in these animals1. A similar capability of enhancement of virulence on the part of intraperitoneally administered cortisone acetate, cholesterol or lecithin with Staphylococcus aureus is reported in this communication.
Increasing alcohol yield by selected yeast fermentation of sweet sorghum. I. Evaluation of yeast strains for ethanol production.

A study was conducted for the purpose of evaluating and selecting yeast strains for their ability to produce ethanol using sweet sorghum juice as the substrate. Stalks of sweet sorghum were obtained by cutting off the tops and stripping away the leaves. Fermentation media were prepared by diluting or adding dextrose to the sorghum juice to give a sugar concentration of either 10% (w/v) or 20% (w/v). All yeast strains were first tested in 10% (w/v) total sugar medium. Those strains showing more than 90% sugar conversion efficiency were further tested in 20% (w/v) total sugar medium. Active cultures for inoculation were prepared by growing the yeast strains on the fermentation medium (10% (w/v) total sugar) for 24 h. Then the cultures were added to the fermentation media at a rate of 2%.
A joint test of risk premia in exchange rates and rational expectations

Abstract This note presents a simple joint test of existence of a risk premium in exchange rates and the rationality of expectations. It is shown that major currency prices studied in this note are subject to a risk premium.
Inductive effect of polar groups on CH and CF stretching vibrations of alkyl and perfluoroalkyl groups and its relation to adsorption

The trifluoromethyl-stretching vibrations for a series of perfluorocarboxylic acids and dihydroperfluoro alcohols were determined using an infrared spectrophotometer, and the results were compared with published information on the methyl-stretching vibrations of the corresponding hydrocarbon compounds. The frequency shifts of the CF3-stretching vibrations are opposite in direction to those of the CH3-stretching vibrations. This opposite shift may be attributed to the inductive effect of highly electronegative fluorine atoms. As a result, the alkyl groups are expected to become somewhat electropositive whereas the perfluoroalkyl groups electronegative. These induced polarities of the nonpolar groups were confirmed by the surface potential measurements at an air-aqueous solution interface and by the electrocapillary and differential capacity measurements at a mercury-aqueous solution interface.
Synthesis and Characterization of Poly(Aryl Ether-Bissulfone)s

Abstract A series of poly(aryl ether-bissulfone)s were synthesized from bis-phenols, 4,4′-bis(4-chlorophenylsulfonyl)biphenyl, and 4,4′-bis(4-fluorophenylsulfonyl)biphenyl. The bishalide monomers were synthesized by reaction of 4,4′-bis(chlorosulfonyl)biphenyl with a suitable aryl halide. Potassium carbonate mediated reaction in di-methylacetamide gave high molecular weight polymers in excellent yield. The polymers are soluble in dipolar aprotic solvents. Unlike the corresponding monosulfone analogues, the poly(aryl ether-bissulfone)s exhibited poor solubility in chlorinated hydrocarbons. The glass transition temperatures of the polymers are among the highest known for poly(aryl ether)s (241-271 °C). In addition, the polymers exhibit excellent thermal stability and they produce clear, colorless tough films by solution casting or compression molding.
Mutagenicity of 5-halodeoxyuridines to diploid human lymphoblasts

Abstract The thymidine base analogues 5-chlorodeoxyuridine, 5-bromodeoxyuridine, and 5-iododeoxyuridine were found to be mutagenic in diploid human lymphoblasts. Mutation was measured as the loss of hypoxanthine-guanine phosphoribosyl transferase activity, which is expressed phenotypically as resistance to 6-thioguanine. Concentration dependence of induced mutant fraction exhibited a maximum for all three compounds. It is postulated that at higher concentrations these thymidine analogues inhibit cytidine diphosphate reductase. Slowed DNA synthesis would result in lower analogue incorporation and thus a lower mutant fraction.
Angiotropism and extravascular migratory metastasis in melanoma: from concept to gene expression

The concepts of angiotropism and extravascular migratory metastasis (EVMM) are now recognized by the international scientific community as a key subject of cancer research. In EVMM, tumor cells migrate along vessels (angiotropic EVMM) or along other anatomical tracks, such as nerves (neurotropic EVMM). Angiotropism has been shown to be a prognostic factor for melanoma metastasis, as well as a microscopic marker of EVMM. For some time, analogies of EVMM with neural crest cell migration and vasculogenesis/angiogenesis have been recognized. Finally, a recent gene microarray analysis has led to the detection of genes potentially involved in EVMM. This article will review our current understanding of EVMM, and new perspectives on this promising field of investigation.
Structural elucidation, using h.p.l.c.-m.s. and g.l.c.-m.s., of the acidic polysaccharide secreted by rhizobium meliloti strain 1021

Abstract An improved, glycosyl-sequencing method has been used for elucidating the structure of the acidic polysaccharide secreted by Rhizobium meliloti strain 1021. The polysaccharide was methylated, the ether partially hydrolysed, the products were reduced, and the alditols ethylated; the resulting mixture of peralkylated oligosaccharide-alditols was analyzed by h.p.l.c.-m.s. Chemical ionization (c.i.) mass spectra were obtained at 2-s intervals, as the various, peralkylated oligosaccharide-alditols were eluted from the h.p.l.c. column. Peralkylated mono-, di-, tri-, and tetra-saccharide-alditols could be readily detected, and at least partially identified, by their M + I ions, in conjunction with other characteristic ions present in their c.i.-mass spectra. The peralkylated di- and tri-saccharide-alditols were further analyzed by g.l.c.-m.s. in the electron-impact mode. The structure of the acidic polysaccharide secreted by R. meliloti strain 1021 is the same as that of the previously characterized polysaccharide secreted by R. meliloti strain U-27.
The influence of level of performance on managerial style: an experimental object-lesson in the ambiguity of correlational data

Abstract Observational studies which seek to evaluate the effect of various leadership styles on subordinate performance can usually be interpreted in the reverse causal direction. To evaluate this alternative interpretation, an experiment was conducted in which performance was manipulated and style observed in a realistic setting. Very strong evidence was obtained that performance shapes the following leadership styles: closeness of supervision, initiating structure, consideration for subordinate.
Pulse mode saturation properties of photomultiplier tubes

The response of an RCA‐4522 photomultiplier tube (35ET bialkali photocathode, 14 dynode stages) in the saturation region has been studied as a function of ambient background light intensity, photocathode illumination area, magnetic field orientation, and ambient temperature. These studies were made using various high‐speed pulsed light sources. It is found that the phototube’s response does vary with some of these parameters (in particular, photocathode temperature effects). However, its response is reproducible and highly successful operation in this region is possible through a series of calibrations.
Microstructural, electrical and magnetic properties of NdBa2Cu3O7-δ prepared from BaO2

NdBa2Cu3O7−δ was synthesized in oxygen from a stoichiometric mixture of Nd2O3, BaO2 and CuO between 890 and 1070 ‡C. The resulting material was composed of small crystals of NdBa2Cu3O7−δ (2 to 10 Μm) and of BaCuO2 as a secondary phase. The effect of the synthesis temperature on the normal-state resistivity, the critical current density and the magnetic susceptibility was investigated. The highestJc values (175 A cm−2) were measured in samples treated between 1010 and 1050 ‡C.
Iridium(I) and Iridium(III) Complexes Supported by a Diphenolate Imidazolyl-Carbene Ligand

Deprotonation of 1,3-di(2-hydroxy-5-tert-butylphenyl)imidazolium chloride (1a) followed by reaction with chloro-1,5-cyclooctadiene Ir(I) dimer affords the anionic Ir(I) complex [K][{OCO}Ir(cod)] (2: OCO = 1,3-di(2-hydroxy-5-tert-butylphenyl)imidazolyl; cod = 1,5-cyclooctadiene), the first Ir complex stabilized by a diphenolate imidazolyl-carbene ligand. In the solid state 2 exhibits square-planar geometry, with only one of the phenoxides bound to the metal center. Oxidation of 2 with 2 equiv of [FeCp2][PF6] generates the Ir(III) complex [{OCO}Ir(cod)(MeCN)][PF6] (3). Reaction of 3 with H2 results in the liberation of cyclooctane and a species capable of catalyzing the hydrogenation of cyclohexene to cyclohexane. Displacement of cyclooctadiene from 3 can be achieved by heating in acetonitrile to form [{OCO}Ir(MeCN)3][PF6] (4) or by reaction with either PMe3 or PCy3 to generate [{OCO}Ir(PMe3)3][PF6] (5) or [{OCO}Ir(PCy3)2(MeCN)][PF6] (6), respectively. 6 reacts with CO in acetonitrile to give an equilibrium...
“It's Hard Getting Kids to Talk about Math”: Helping New Teachers Improve Mathematical Discourse

Abstract This article examines how two new teachers, with varied content knowledge and preparation as teachers in mathematics education, improved their use of whole-class discourse in their mathematics classes with a mentor's assistance. Discourse has long been shown to be influential in supporting students' learning of mathematics, but the implementation of these practices can be a struggle for new teachers. To the initial surprise of both teachers, the observational data did not coincide with the perceptions that the teachers had of their practice. However, with structured and frequent support from a mentor, along with observational data, there were noticeable improvements in both teachers' ability to facilitate mathematical discourse. By the end of the term, the teachers included more students in discussions, asked more questions that probed for understanding, and reduced the amount of time spent delivering instruction. The strengthening of students' understanding of mathematics through communication i...
Supporting unstructured workflow activities in the Bramble ICN system

Workflow systems have been proposed as a means for automating business procedures. While growing in popularity, many fundamental problems, such as supporting unstructured office activities, still remain before this technology will be especially useful in the office. This paper examines difficulties associated with handling unstructured office activities and argues that it is both necessary and possible for workflow technology to better support office workers who perform these activities. The approach illustrated in this paper advocates reducing the rigidity of the workflow system's computational model, which, in turn, requires the system to better support the contextual information needs of the workers performing the unstructured activities.