cssi/SciSciGPT-SciSciNet huggingface dataset:
Computer Educational Datapath (CED): basic computer design for K-12 education

Through the educational tools that we are developing, the building blocks of computer hardware can be explored by middle school and high school students. The main purpose of this educational tool is to initiate interest in digital hardware design through the demonstration of computer processor design. The Computer Educational Datapath (CED) allows the user to build and program a single-cycle datapath. The CED is a versatile, programmable, computer datapath enhanced with input and output. Unique features of this device include its ability to be reconfigured for larger data loads to allow the user full access to supported instructions and to provide full programmability of basic computer algorithms. The CED has the potential to influence students in their interaction with one of the most powerful tools of all times - the computer.
Capacity and the obstacle problem

For the bilinear forma(u, v) = źΩaij(x)uxivxjdx, whereu, vźH01(Ω), Ω a bounded domain in źn, andaij(x) bounded and uniformly elliptic coefficients on Ω, theLp integrability on Ω forp>2n/(nź2) of the solution to the variational inequality (the unilateral obstacle problem with obstacle $$a(u,v - u) \geqslant \left\langle {f,v - u} \right\rangle , f \in H^{ - 1} (\Omega ),$$ is studied. Hereź is an arbitrary function given on Ω andC is the Newtonian conductor capacity relative to Ω. The sufficient conditions that permit such quantitative estimates are given in terms of capacitary integrals on Ω:ź|ź|qdC<ź. Some simple examples show that is not sufficient to assume merely thatźźH01(Ω)źLq(Ω) for sufficiently largeq. In particular, $$\mathbb{K}_\psi \ne \emptyset $$ precisely whenźź+2dC<ź. An estimate is also given for theLp norm of the gradient of such solutions in terms of these integrals.
Police Use Of Force And Suspect Resistance: The Micro Process Of The Police-Suspect Encounter

Using data collected as part of an observational study of the police in Indianapolis, Indiana, and St. Petersburg, Florida, this research examines 3,544 police-suspect encounters in an attempt to better understand the application of nonlethal force and the relationship between officer use of force and suspect resistance. More specifically, it examines the extent of and variation in force and resistance and the interplay between the two. Results show that when both verbal and physical forms of coercion are considered, force occurs quite frequently—in more than half of all encounters. Conversely, suspects displayed some form of resistance in 12% of all encounters. When multiple uses of force and resistance within individual encounters are considered, the frequency of both behaviors increases substantially. In addition, a majority of both forceful and resistant behaviors fall on the lower end of continuum (e.g., verbal commands as opposed to striking with a baton). Encounters that began with some form of for...
Social behaviour. foraging efficiency and habitat utilization in a group of tropical herbivorous fish

Abstract In this study schooling and solitary behaviour in a group of tropical herbivorous fish were compared. Three species of acanthurids are common herbivores on the coral reef off the coast of Belize, Central America. In the high spur and groove habitat, individuals of all three species of fish were seen exhibiting both solitary and schooling behaviour. Individuals commonly moved in and out of schools. Solitary fish foraged primarily in the groove microhabitat and received attacks more frequently from territorial herbivorous competitors (pomacentrids). The schooling fish foraged more frequently in the spur microhabitat and in pomacentrid territories, but received fewer attacks from territorial pomacentrids. Paired-choice feeding trials indicated that the algal turfs from the spur microhabitat were greatly preferred. Solitary individuals also visited cleaning stations more frequently. At cleaning stations, juvenile labrids removed trematodes from the acanthurid's skin. The mixed-species schooling appears to be a means by which acanthurids can forage in a microhabitat on a preferred resource while circum venting the territoriality of a herbivorous competitor. The solitary behaviour allows individuals to visit cleaning stations more frequently.
Beam Diagnostics on the ZGS

The detection equipment installed in the Zero Gradient Synchrotron (ZGS) is described. Most measurement techniques and equipment are similar to those of other synchrotrons with the possible exception of fluorescent screens of high transmission viewed by storage TV systems. We find these useful for a variety of diagnostic techniques at injection, such as measurement of equilibrium orbits, median plane, injection angles, and angular spreads. The value of these techniques, which depend upon the focussing properties of the synchrotron, lies in their ability to separate magnet effects from injection effects. These techniques are described in some detail. Also discussed briefly are some of the problems that we have encountered, such as unbalanced ground currents, tune variation during the accelerating cycle, and a vertical instability with a sharp intensity threshold.
Localization of culprit lesions in coronary arteries of patients with ST-segment elevation myocardial infarctions: Relation to bifurcations and curvatures

Background Although culprit lesions in ST-segment elevation myocardial infarction (STEMI) cluster in the proximal coronary arteries, their relationship to bifurcations and curvatures, where blood flow is disturbed, is unknown. We hypothesized that ( a ) culprit lesions localize to disturbed flow distal to bifurcations and curvatures and ( b ) the distribution of culprit lesions in the left (LCA) and right coronary arteries (RCA) and resulting infarct size are related to the location of bifurcations and curvatures. Methods Emory University's contribution to the National Cardiovascular Data Registry was queried for STEMIs. Using quantitative coronary angiography, the distances from the vessel ostium, major bifurcations, and major curvatures to the culprit lesion were measured in 385 patients. Results Culprit lesions were located within 20 mm of a bifurcation in 79% of patients and closer to the bifurcation in the LCA compared with the RCA (7.4 ± 7.3 vs 17.7 ± 14.8 mm, P P = .0003) and were associated with larger myocardial infarctions as assessed by peak creatine kinase–MB (208 ± 222 vs 140 ± 153 ng/dL, P = .001) and troponin I (59 ± 62 vs 40 ± 35 ng/dL, P = .0006) and with higher in-hospital mortality (5.2% vs 1.1%, P = .04). Conclusions In patients with STEMI, culprit lesions are frequently located immediately distal to bifurcations and in proximity to major curvatures where disturbed flow is known to occur. This supports the role of wall shear stress in the pathogenesis of STEMI.
Effects of Mentoring on the Development of Leadership Self‐Efficacy and Political Skill

This study of 260 business graduate students considered the relationship between mentoring and leadership self-efficacy, and mentoring and political skill. Comparisons between nonmentored and mentored individuals showed that having a mentor was associated with increased political skill but not with increased leadership self-efficacy. Among mentees, higher quality mentoring relationships were associated with significantly higher leadership self-efficacy but not with significantly higher political skill. Results suggest that the presence of a mentor affects protege development of political skill, but the quality of the relationship is important for protege development of leadership self-efficacy.
Cu films on a Zn-terminated ZnO(0001) surface: structure and electronic properties

Abstract The structure and electronic properties of ultrathin, vapor-deposited Cu films on a Zn-terminated ZnO(0001)-Zn surface have been studied with low-energy ion scattering spectroscopy (ISS), X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD), low-energy electron diffraction (LEED), work function and band bending measurements. Below ∼5% of a monolayer (ML), the Cu is very weakly cationic, but thereafter, it is practically charge-neutral and clustered into islands with strong Cu–Cu bonding. Up to ∼33% of a ML, these islands are only one atom thick, and the Cu atoms do not sit in preferred substrate lattice sites. Above ∼33% of a ML, additional Cu adds predominantly on top of existing Cu islands, to make three-dimensional (3D) Cu islands. These eventually adopt a Cu(111) structure, rotationally aligned with the ZnO(0001) substrate, when the individual islands are 3 ML thick or thicker. Annealing above 500 K causes the islands to irreversibly thicken, thus uncovering part of the ZnO surface. The results are compared to Cu films on other faces of ZnO, showing that the geometry of the ZnO surface has only minor effects on the Cu film properties, although the conversion from 2D to 3D islands happens at a lower coverage on this Zn face than on the O face.
Transposon mutagenesis of type III group B Streptococcus: correlation of capsule expression with virulence

The capsular polysaccharide of type III group B Streptococcus (GBS) is thought to be a major factor in the virulence of this organism. Transposon mutagenesis was used to obtain isogenic strains of a GBS serotype III clinical isolate (COH 31r/s) with site-specific mutations in the gene(s) responsible for capsule production. The self-conjugative transposon Tn916 was transferred to strain COH 31r/s during incubation with Streptococcus faecalis strain CG110 on membrane filters. Eleven transconjugant clones did not bind type III GBS antiserum by immunoblot. Immunofluorescence, competitive ELISA, and electron microscopy confirmed the absence of detectable GBS type III capsular polysaccharide in one of the transconjugants, COH 31-15. Southern hybridization analysis with a Tn916 probe confirmed the presence of the transposon sequence within each mutant. A 3.0-kilobase EcoRI fragment that flanked the Tn916 sequence was subcloned from mutant COH 31-15. This fragment shared homology with DNA from the other GBS serotypes, suggesting a common sequence for capsulation shared by organisms of different capsular types. Loss of capsule expression resulted in loss of virulence in a neonatal rat model. We conclude that a gene common to all capsular types of GBS is required for surface expression of the type III capsule and that inactivation of this gene by Tn916 results in the loss of virulence.
Membrane potential of phospholipid bilayers: Ion concentration and pH difference

A study was made of transmembrane potentials at the initial state produced by a concentration gradient of identical ions and also different ionic species at the same concentration for various phospholipid bilayers. It was found that the potential of the salt added side was lower than that on the other side of the membrane. For the phosphatidylserine and phosphatidylethanolamine membranes, there was a significant difference between the potentials produced by the addition of the same concentrations of KCl and NaCl, respectively, on one side of the membrane, whereas, for the phosphatidylcholine membrane, there was no appreciable difference in produced membrane potentials. The produced membrane potential reached saturation with high concentration of salt on one side. For the cases of the addition of divalent ions, it was found that even a low concentration of CaCl2 on one side of the phosphatidylserine membrane resulted in a large membrane potential, which suggests a strong interaction of Ca2+ with phosphatidylserine molecules. The presence of a pH difference between the two sides of the phosphatidylserine membrane also produced membrane potentials, but, for the phosphatidylcholine membrane, there was no appreciable change in the produced membrane potential. It is concluded that these membrane potentials observed at the initial state of the system are produced mainly by the difference between two diffused double-layer potentials formed at the interface of the membrane and the electrolyte solution on both sides and not by the ion diffusion across the membrane.
The effect of subsampling sites within patients.

In recent periodontal research, multiple sites within patients have been utilized as the primary observations or sampling units. In the present study a simple approach for the single sample case was used to demonstrate the effect of site-specific analyses when the patient is not treated as the sampling unit. This approach was shown to underestimate the variance of the mean value in question and thus, in tests of hypotheses concerning the mean, lowers artificially the p-level or equivalently raises artificially the 1-α confidence level of intervals. The error introduced by this procedure increased when the number of actual primary random sampling units (the patients) was small, for this resulted in inappropriately lowered Student's tvalues. The error also increased as the number of sites used within patients increased and decreased slightly as the number of patients increased. From only six periodontal patients where six randomly chosen sites were observed for pocket depth in mm, a statistically significant (p<0.01) intraclass correlation was seen (ϱ1=0.31). If the 36 sites had been treated as independently distributed, a true probability of p(true)=0.27 would have been misread nominally as p(nominal)=0.05.
Forced and Internal Twentieth-Century SST Trends in the North Atlantic*

In recent years, two alarming trends in North Atlantic climate have been noted: an increase in the intensity and frequency of Atlantic hurricanes and a rapid decrease in Greenland ice sheet volume. Both of these phenomena occurred while a significant warming took place in North Atlantic sea surface temperatures (SSTs), thus sparking a debate on whether the warming is a consequence of natural climate variations, anthropogenic forcing, or both; and if both, what their relative roles are. Here models and observations are used to detect and attribute long-term (multidecadal) twentieth-century North Atlantic (NA) SST changes to their anthropogenic and natural causes. A suite of Intergovernmental Panel on Climate Change (IPCC) twentieth-century (C20C) coupled model simulations with multiple ensemble members and a signal-to-noise maximizing empirical orthogonal function analysis are used to identify a model-based estimate of the forced, anthropogenic component in NA SST variability. Comparing the results to observations, it is argued that the long-term, observed, North Atlantic basin-averaged SSTs combine a forced global warming trend with a distinct, local multidecadal ‘‘oscillation’’ that is outside of the range of the model-simulated, forced component and most likely arose from internal variability. This internal variability produced a cold interval between 1900 and 1930, followed by 30 yr of relative warmth and another cold phase from 1960 to 1990, and a warming since then. This natural variation, referred to previously as the Atlantic Multidecadal Oscillation (AMO), thus played a significant role in the twentieth-century NA SST variability and should be considered in future, near-term climate projections as a mechanism that, depending on its behavior, can act either constructively or destructively with the region’s response to anthropogenic influence, temporarily amplifying or mitigating regional climate change.
A Dynamic Model of Candidate Fundraising: The Case of Presidential Nomination Campaigns

Despite the scholarly interest in presidential nomination campaigns, existing research has given limited attention to the role of fundraising in these campaigns. I attempt to fill this void by developing a model based upon the hypothesized relationship between candidates' electoral suc cess and increases in their subsequent fundraising. Using data from three recent nomination campaigns and pooled cross-sectional time-series analy ses, I present results suggesting that success and media coverage have a strong impact upon the subsequent fundraising of long-shot candidates, while the subsequent fundraising of established candidates is attribut able to their viability The observed differences in the relationship are due to the expectations associated with the two candidate types.
Frequency of Sighs in Premature Newborns Requiring Nasal Continuous Positive Airway Pressure (NCPAP)

Frequency of Sighs in Premature Newborns Requiring Nasal Continuous Positive Airway Pressure (NCPAP)
The mean duration of gastroesophageal reflux during sleep as an indicator of respiratory symptoms from gastroesophageal reflux in children

Abstract The coexistence of gastroesophageal reflux (GER) and respiratory symptoms has been reported in children, but identifying a reliable indicator of reflux-induced respiratory symptoms has been difficult. The mean duration of reflux episodes during sleep (ZMD), extracted from a 18- to 24-hour esophageal pH recording, has been presented previously as a reliable correlate of respiratory symptoms caused by GER in infants. To reexamine the accuracy of the ZMD we report 519 consecutive children with respiratory symptoms (aged 1 week to 15 years) who were referred for documentation of GER by 18- to 24-hour esophageal pH monitoring. Follow-up information was obtained on 388 patients 1 to 115 months later (mean, 23 months). From the follow-up information, 259 children could be reliably classified; 128 as having reflux-related and 131 as having reflux-unrelated respiratory symptoms. None of the 131 children with reflux-unrelated respiratory symptoms had a prolonged ZMD (> 3.8 minutes). In comparison, 119 of the 128 children (93%) with reflux-related respiratory symptoms had a prolonged ZMD ( P
Natural convection flow in a finite, rectangular slot arbitrarily oriented with respect to the gravity vector

Solutions to the stationary two-dimensional equations of motion governing natural convection flow of a large Prandtl number Boussinesq fluid contained in a differentially heated inclined rectangular slot have been obtained by the Galerkin method. The problem has been solved for perfectly conductive and adiabatic boundary conditions on the border strips. The range of parameters investigated include: Rayleigh numbers up to 2 × 106, aspect ratios from 0.1 to 20, and tilt angles from −30° (bottom plate hotter) to + 75° (top plate hotter). These parameters describe both the conduction and boundary layer regimes. The computed flow distributions, including the appearance of multicellular flows, the temperature profiles, and the heat transfer predictions compare favorably with experimental results, and with other numerical studies.
Scale and pattern of cheatgrass (Bromus tectorum) invasion in Rocky Mountain National Park.

ABSTRACT: Cheatgrass (Promus tectorum L.), a winter-annual grass native to Eurasia, is one of the most widely distributed and damaging invasive annual grasses in North America. We studied the scale and pattern of cheatgrass in Rocky Mountain National Park, Colorado, examining possible dispersal and disturbance mechanisms and inherently susceptible environmental characteristics that may facilitate the spread of cheatgrass in the park. We distinguished facilitating factors related to land uses and natural processes. We mapped (with GPS) cheatgrass patches along randomly selected transects along roads, trails, in natural vegetation, and around developments. For each patch, we recorded: (1) patch size, (2) percentage cover of cheatgrass, (3) characteristics of microenvironments, and (4) amount of cheatgrass within microenvironments. Using MANOVA, we found that, at a broad scale, cheatgrass is concentrated on the east side of the park, at lower elevations, and in grassland and shrubland vegetation, with roads ...
Effect of vacuum-packaged frozen storage, after cooking, on the phospholipids of Hereford and Bison.

Abstract Changes in the neutral lipid (NL), phospholipid (PL) and their fatty acid (FA) profiles in lean samples of cooked and cooked, vacuum-packaged, frozen (28 days) Hereford and Bison L. dorsi muscle were analyzed. Samples from Herefords contained more saturated fatty acids (SFA) in the neutral lipid fraction than Bison. Storage decreased the C 18:2 , C 18:3 , C 20:1 and C 20:4 content of the NL. Bison samples contained more total PL and phosphatidylethanolamine (PE) than Hereford. Storage decreased the content of the least polar of the PL which were eluted in the solvent front (fraction 1), phosphatidylinositol (PI), phosphatidylserine (PS), PE and sphingomyelin (SPH). In the combined PL fraction, there were no differences in the FA profile of Bison and Hereford. Storage resulted in a decrease in the content of C 18:2 , C 20:4 , unsaturated fatty acid (UFA) and polyunsaturated fatty acid (PUFA) in the combined PL fraction. In the PE fraction, Bison samples contained more C 20:4 and PUFA than Hereford. Storage had no effect on the FA profile of PE. The LPC fraction of Bison samples contained more saturated SFA, UFA and PUFA than Hereford, and with storage these FA decreased. Cooked frozen storage also decreased SFA, UFA and PUFA in PC/LPE.
Squish and CuAAC: additive-free covalent monolayers of discrete molecules in seconds.

A terminal alkyne is immobilized rapidly into a full monolayer by squishing a small volume of a solution of the alkyne between an azide-modified surface and a copper plate. The monolayer is covalently attached to the surface through a copper-catalyzed alkyne–azide cycloaddition (CuAAC) reaction, and the coverages of the immobilized electroactive alkyne species are quantified by cyclic voltammetry. A reaction time of less than 20 s is possible with no other reagents required. The procedure is effective under aerobic conditions using either an aqueous or aprotic organic solution of the alkyne (1–100 mM).
Percolation behavior in morphology and modulus of polymer blends

The tensile property of a plastic/rubber blend depends critically on the morphology and connectivity of the two phases. At low plastic volume fractions, the plastic phase forms isolated domains in the matrix of rubber phase, and the tensile property of the blend is largely controlled by the continuous rubber phase. As the plastic volume fraction increases, the plastic phase gradually connects into a pervasive network that eventually dominates the tensile and shear properties of the blend. The transition of the blend from a rubber-dominated to a plasticdominated behavior is a manifestation of percolation transition. The plastic volume concentration at which the transition takes place is the percolation threshold. Its dependence on morphology is discussed by contrasting the behaviors of anisotropic injection-molded specimens vs. isotropic compression-molded specimens of the two-phase blends of an amorphous thermoplastic polyester, PETG, and an ethylene-propylene-diene rubber, EPDM. It is found that the tensile modulus just above the percolation threshold obeys a power law as a function of the plastic volume concentration in excess of the percolation threshold. By analyzing the longitudinal tensile modulus of injection-molded PETG/EPDM specimens just above the threshold, it is shown that the scalar elastic percolation theory of de Gennes is at work here. For compression-molded PETG/EPDM specimens, it is found that the isotropic tensile modulus over the entire composition range obeys the symmetric effective medium theory.
Target tracking for land mine detection

This paper presents a simple target-tracking algorithm for use on a vehicle platform for landmine detection. Data from three landmine detection sensors mounted at the front of the vehicle enhance the probability of detection and, when combined via data fusion, reduce the false alarm rate to practical levels. The output of the data fusion process is a target position that must be tracked to either a marking nozzle array or point confirmation sensor mounted at the back of the vehicle.
Plasma endotoxin concentration in horses: a methods study.

Background: Accurate determination of plasma endotoxin concentration is critical for ex vivo and in vitro cellular and molecular studies of endotoxemia in horses. However, reports are conflicting with respect to anticoagulant, handling, and sample preparation. Objective: The purpose of this study was to determine the effect of blood sample fraction and handling time on measurement of endotoxin concentration in horses. Methods: Whole blood, anticoagulated with 3.8% (0.12 M) sodium citrate (9:1), was collected from 5 healthy horses. Whole blood (WB), platelet-rich plasma (PRP), and platelet-poor plasma (PPP) were spiked with endotoxin (2 EU/mL). Endotoxin-spiked WB samples were centrifuged immediately to generate PRP for measurement. Endotoxin concentration was subsequently measured by Limulus amebocyte assay at 0, 15, 30, 45, and 60 minutes. Assays were performed in triplicate and results were analyzed using Student's t-test, with significance set at P < .05. Results: Mean endotoxin concentrations in 2 EU/mL-spiked WB were significantly different from those in PPP at all time points tested. Recovery of endotoxin in PRP generated from WB was significantly diminished after just 15 minutes. Conclusion: PRP generated from WB is significantly more reliable than PPP in determining endotoxin concentration ex vivo. Measurement of endotoxin in PRP generated from WB was significantly diminished after 15 min, identifying a time frame within which to process blood samples for endotoxin analysis.
Mathematical modeling of immunity to malaria

Abstract A comparison of two epidemiological models of immunity to malaria shows that different characterizations of immunity boosted by exposure to infection generate qualitatively different results. Attempts to control disease by reducing transmission or increasing the recovery rate can produce an increase in prevalence in the compartmental model with discrete epidemiological states. However, the parasite density always decreases in response to disease control in the model with continuous epidemiological variables. Each model accounts for some epidemiological patterns. The increase in prevalence seen in the compartmental model is in accord with observed effects of variation in transmission. Parasite suppression in areas of antimalarial drug use is consistent with the effect of an increased recovery rate in the density model. Future work should combine the two approaches, perhaps by using the compartmental model over the low to moderate range of infection rates and switching to the density model at high infection rates. In any case, the validation of models needs to take account of the usage of antimalarial drugs as well as the intensity of transmission.
Verrucous carcinoma of the renal pelvis

We report a case of a verrucous carcinoma of the renal pelvis after a long history of a renal pelvis stone. Only 1 case of verrucous carcinoma of the renal pelvis has been previously reported, and ours is the first case not associated with a horseshoe kidney.
The three-salesmen conundrum in medicine.

treats the patient and the patient does not have a urinarytract infection (cell B) than when the physician treats the patient and the patient does have a urinary-tract infection (cell A). When probed further, it becomes apparent that the physicians are not concerned that the incorrect diagnosis means missing a more dangerous medical condition. Rather, they reason that the mistake of prescribing something unnecessary further detracts from the value to the patient. In doing so, they double count the unnecessary treatment. The correct answer is revealed when one considers that antibiotics are prescribed in both cases, and it should be better that the patient does not have a urinary-tract infection than has one. The same double-counting occurs with diagnosis—eg, when a physician orders brain magnetic-resonance imaging for a patient and, when the test is negative, feels disappointed about a wasted test rather than happy about the result. Those clinicians who anticipate that regret might order too few tests.
Solution properties of semirigid polyquinolines. I. Size‐exclusion chromatography with light‐scattering detection of poly[2,2′‐(P,P′‐oxydi‐P‐phenylene) 6,6′‐oxybis(4‐phenylquinoline)]

An aromatic semirigid polyquinoline, poly[2,2′-(p,p′-oxydi-p-phenylene) 6,6′-oxybis(4-phenylquinoline)], has been studied in dilute solution using viscometry, light scattering, and size-exclusion chromatography coupled with low-angle light-scattering detection (SEC/LALS). The SEC/LALS technique permits determination of the intrinsic viscosity and absolute molecular weight for a series of narrow fractions without preparative fractionation. Aggregation that was observed in dilute chloroform solutions was found to be related to protonation of the polyquinoline by HCI present in chloroform. Unperturbed dimensions calculated from the SEC/LALS results show the chain to have nearly freely rotating dimensions, as expected for a chain composed of long (12-A) rigid segments connected by ether linkages.
Elastomeric microwire-based optical gas flowmeter with stretching-enabled tunability in measurement range.

We report the utilization of transparent poly(dimethylsiloxane) (PDMS) microwires as the transducer for optical gas flowmetry. The elasticity of the PDMS microwire was exploited not only to miniaturize and simplify the flowmeter but also to widen and tune the measurement range through mechanical stretching. Using a 9 mm long microwire, we achieved 2.8∼9.8 dB/SLM sensitivity. A 500 μm stretching of the microwire also shifted the measurement range from 1 to 4 SLM. The experimental results agreed well with predictions based on the fluid dynamic/optical model.
Two-Photon Absorption of Biexcitons for a Truncated Potential

A tight binding, one dimensional, two−band model is used to investigate the formation and nonlinear optical properties of biexcitons in conjugated polymers. The full single and double electron−hole pair basis sets are explicitly considered for a Hamiltonian which includes an electron and hole transfer parameter (t) along with a truncated potential with only on−site (V0) and nearest neighbor (V1) Coulombic interactions. The biexciton phase space is determined to be a function of only two parameters α and β where α = V1/V0and β = t /V0. Due to the truncated potential only a single biexciton eigenstate is formed in the region limited by 0.64 <α ≤1 and 0 ≤β <0.33. The two−photon absorption spectra in the range 0 <hω) <∆, where ∆ is the one photon gap, are found to contain at most two types of peaks: one arising from a biexciton and another due to a charge-transfer, single−exciton. The polymer limit is obtained and used to investigate polymers with large alternation such as polysilane.
Coherent functors and families of space curves

We give a summary of Auslander's theory of coherent functors and its application to the study of flat families in projective three-space. This is joint work with M. Martin-Deschamps and D. Perrin. Full details will appear in the paper [3], [4], [5], [6].
Cellular electrophysiology of WAY-123,398, a new class III antiarrhythmic agent : specificity of IK block and lack of reverse use dependence in cat ventricular myocytes

Objective: The objectives were (a) to evaluate the effects of WAY-123,398, a new class III antiarrhythmic agent, on the action potential of canine Purkinje fibres in comparison with dofetilide, E-4031, and dl-sotalol, and (b) to characterise the mechanism of the class III action by studying its effects on several ionic currents in isolated cat myocytes. Methods: Transmembrane potentials in Purkinje fibres were studied with standard microelectrodes filled with 3M KC1. Myocytes were isolated by enzymatic disaggregation with collagenase and current recordings were obtained by voltage clamp with either the nystatin perforated patch technique or the usual whole cell configuration. Results: WAY-123,398 prolonged action potential duration (APD) in Purkinje fibres and in cat ventricular myocytes without altering other variables of the action potential; in Purkinje fibres the concentration producing a 20% prolongation of APD−60 mV at a basic cycle length of 1000 ms was 0.2 μM. After depolarising voltage steps, the delayed rectifier (IK) peak tail currents in cat myocytes were blocked with IC5()=0.1 μM. The block was unaffected by varying the duration (200 to 500 ms) or the frequency (0.4 to 2.5 Hz) of the depolarising steps. A much higher concentration of WAY-123,398 (10 μM) did not have effects on the L type Ca current (ICa-L), and on the inward rectifier (IKI) and transient outward (Ito) K currents. Conclusions: The results indicate that WAY-123,398 is an effective and specific class III agent devoid of class I activity, and suggest that WAY-123,398 prolongs cardiac repolarisation by specifically blocking the delayed rectifier current (IK). The block was unchanged over a range of frequencies and duration of depolarisation, showing no evidence of “reverse use dependence” of block. Cardiovascular Research 1993; 27 :000-000
Nonequilibrium hot-electron transport in optically irradiated YBCO films

Abstract Sputtered high-T c YBa 2 Cu 3 O 7 films ≈ 1 μm thick have been subjected to optical pulses, 100 ps in duration, from a Nd:YAG laser. Switching from the superconducting to the normal state was observed in times of order 1 ns. Since equilibrium thermal transport cannot distribute heat from the top absorbing layer (≈0.1μm thick) through the film on this time scale, an alternative nonequilibrium mechanism must be responsible. Evidence is presented for energy distribution via nonequilibrium hot electrons on the 1 psec time scale. For times of order 100 ps or longer, however, the response appears to be essentially bolometric (i.e. thermal). Prospects for direct observation of a nonequilibrium electronic component are discussed, together with potential application to an ultrafast switch.
The chemical reactivity of phosphorus-bridging carbonyl compounds: a novel approach to homogeneous catalysis?

Abstract The use of a bicyclic metal carbonyl matrix allows the stabilization of phosphorus-bridging carbonyl groups in air-stable, readily synthesized iron carbonyl derivatives of the general type (R 2 NP) 2 COFe 2 (CO) 6 (R 2 N= bulky dialkylamino group, particularly iPr 2 N). Such phosphorus-bridging carbonyl derivatives readily undergo extrusion of the phosphorus-bridging carbonyl group at ∼100°C to give a (R 2 NP) 2 Fe 2 (CO) 6 unit with reactive sites on the phosphorus atoms which can be trapped by a variety of reagents. For example, alcohols trap (iPr 2 NP) 2 Fe 2 (CO) 6 as (ROPN-iPr 2 )(iPr 2 NPH)Fe 2 (CO) 6 whereas the (iPr 2 NP) 2 Fe 2 (CO) 6 unit can also add to the CN of acetonitrile or benzonitrile, the CO of aldehydes, ketones, or even maleic anhydride, and the CC of acrylonitrile. The phosphorus-bridging carbonyl extrusion chemistry of (iPr 2 NP) 2 COFe 2 (CO) 6 suggests the possibility of designing novel synergistic catalyst systems in which reactive vacant sites are generated at phosphorus atoms adjacent to vacant sites on transition metal atoms.
The role of footwear in childhood injuries.

To assess the influence of footwear on injury, we prospectively studied all injured children presenting to the Emergency Department of The Children's Hospital of Philadelphia during February, May, July, and October 1988. Information was collected concerning the type and characteristics of footwear worn and environmental factors. Comparisons were made between those involving and those not involving loss of footing (LOF) during injury. Of the 3015 children studied, LOF occurred in 1075 (35.8%). Overall, significantly more injuries involved LOF in children whose feet were covered (n = 946, 37.0%) than in those who were barefoot (n = 129, 29.1%) at the time of injury (P less than 0.001). However, children wearing low-top sneakers had the lowest rate of LOF (24.0%) of any group. Children wearing rough-sole footwear had LOF significantly less frequently (24.2%) than those wearing smooth-sole footwear (51.8%; P less than 0.001). Rubber-sole footwear was less frequently associated with LOF (n = 488, 28.6%) than were other sole materials (n = 457, 53.8%; P less than 0.001). Our data suggest a potential injury prevention strategy involving utilization of rough-sole footwear. Language: en
Review of Edward A. Purcell, Jr., Brandeis and the Progressive Constitution: Erie , the Judicial Power, and the Politics of Federal Courts in Twentieth‐Century America

One of my strongest memories of law school remains the first class in “Federal Courts.” The teacher began by asking if anyone could explain the holding in Erie Railroad Co. v. Tompkins (1938).2 Several students raised their hands, and the answer was soon forthcoming. Federal courts were bound by the decisional rules of the state courts in the states in which theywere located; there is no federal common law. “Very good,” the teacher said. “If you know that, why are you taking this course?”
Physicians and medical education.

Certain occasions prompt evaluation of and reflection on our current state of affairs and our future direction. Such is the case with the centennial of The University of Texas Medical School at Galveston. Inasmuch as a medical school provides the foundation for future physicians to practice medicine with compassion and to actively seek solutions to medical dilemmas, interpersonal skills and critical thinking are essential to the future of medicine. We must face the problems encountered in the process of educating physicians and implement changes that assure that these elements of compassion and critical analysis are passed on to our future colleagues. Physicians who are engaged in the practice of medicine on a full-time basis (hereafter referred to as practicing physicians) can help us impart these elements to our students. In addition, they can help identify other essential components of medical practice that should become part of medical education. A central
Chronic Hyperglycemic Diabetes in the Rat is Associated with a Selective Impairment of Cerebral Vasodilatory Responses

Diabetes has been reported to impair vasodilatory responses in the peripheral vascular tissue. However, little is known about vasodilatory function in the diabetic brain. We therefore studied, in the N2O-sedated, paralyzed, and artificially ventilated rat, the effects of chronic hyperglycemic diabetes on the cerebral blood flow (CBF) responses to 3 acutely imposed vasodilatory stimuli: Hypoglycemia (HG) (plasma glucose = 1.6–1.9 μmol ml−1), hypoxia (HX) (PaO2 = 35–38 mm Hg), or hypercarbia HC) (PaCO2 = 75–78 mm Hg). In addition, we evaluated the somatosensory evoked potential (SSEP) and plasma catecholamine changes in rats exposed to acute glycemic reductions. Diabetes was induced via streptozotocin (STZ, 60 mg kg−1 i.p.). All results in diabetic rats were compared to those obtained in age-matched nondiabetic controls. The animals were studied at 6–8 weeks (HG experiments) or 4–6 months (HG, HX, and HC experiments) post-STZ. Values for CBF were obtained for the cortex (CX), subcortex (SC), brainstem (BS),...
Superinfection immunity and prophage repression in phage P1.

Abstract A lysogen for P1d91tet, a defective prophage produced by recombination between P1 and an R factor, is not immune to superinfection by phage P1. However, marker rescue experiments demonstrate that the wild type form of the P1 repressor gene (c1+), whose action is necessary for the maintenance of a P1 prophage, is present in d91tet. Furthermore, the c1+ gene is active in a P1d91tet lysogen, since a single lysogen for a recombinant P1d91tet plasmid into which a c1ts mutation has been introduced is thermo-inducible. It is therefore concluded that superinfection immunity of a prophage is controlled, at least in part, by a different part of the P1 genome from that needed for prophage repression (gene c1). Marker rescue experiments using the d91tet lysogen allow us to determine the relative order of the genes near the “right-hand” end of the vegetative P1 map, including gene c1.
Complexes of functionally modified hydrazone ligands—square, rectangular (M4), trigonal bipyramidal (M5) and pin-wheel (M6) motifs

Hydrazone ligands modified with benzothiazole and oxime groups produce spin-coupled tetra- (Mn, Ni, Cu), penta- (Co), and hexanuclear (Cu) self-assembled clusters.
Slow potential shifts in dorsal hippocampus during “epileptogenic” perfusion of the inferior horn with high-potassium CSF

Abstract Slow potential shifts and responses to ipsi- and contralateral stimulation of dorsal hippocampus were recorded from basal and apical dendritic layers in awake cats, using chronically implanted pipettes (50 μ tip). Perfusion of the inferior horn with CSF in which K + concentration was raised from normal 3 mEq/l to 9–18 mEq/l induced, after 20–50 sec, an early DC shift (1–3 mV) only in the basal dendritic layer, reaching a plateau after 2–3 min. During this time no changes in the pattern of hippocampal evoked responses were observed. In the following period while the DC level was constant, large potentials, negative in basal dendrites and positive in apical dendrites, gradually developed in response to single stimuli, reaching a peak in 6–15 min when a seizure discharge was triggered. During the last minute preceding the initiation of paroxysmal discharge, the main transient of each response was followed by a long-lasting negative wave from basal dendrites and a synchronous positive wave from apical dendrites. At this moment another DC shift occurred by the overlapping of these late waves. Paroxysmal discharges then were superimposed on this DC shift. After the perfusion was discontinued the excitability remained increased as 3/sec stimuli, without such effect before perfusion, were able to trigger seizure discharges. During this same period the DC level in the apical dendritic layer did not change significantly but that from the basal layer slowly shifted to above its initial value. It is assumed that the initial DC shift, recorded only from the periventricular electrodes, was connected with changes in ependymovascular membranes, and that the K + increased epileptogenic excitability by another mechanism than a global gradual depolarization of neurons. The slow potential shift accompanying the seizure was generated apparently by the development of “paroxysmal depolarization and hyperpolarization shifts” at the level of basal and apical dendrites.
Intrahepatic Biliary Enteric Bypass Provides Effective Palliation in Selected Patients with Malignant Obstruction at the Hepatic Duct Confluence

Abstract Background: Palliating the effects of biliary obstruction is a major goal of therapy in patients with cancer at the hepatic duct confluence. This study was undertaken to evaluate the effectiveness of intrahepatic biliary-enteric bypass to either the segment III duct or the right sectoral hepatic ducts in patients with unresectable hilar cholangiocarcinoma or gallbladder carcinoma. Methods: From December 1991 to October 1996, 55 consecutive bypass procedures were prospectively evaluated in patients with unresectable hilar cholangiocarcinoma or gallbladder cancer. Patients were divided into three groups based on the primary tumor and the type of bypass performed: group 1A, cholangiocarcinoma/segment III bypass (n = 20); group 1B, cholangiocarcinoma/right sectoral hepatic duct bypass (n = 14); group 2, gallbladder cancer/segment III bypass (n = 21). Results: Mean hospital stay (14 ± 2 days) and mean blood loss (629 ± 84 mL) were similar among the three groups. Perioperative death occurred in 6 patients (11%): 0 in group 1A, 3 each in groups 1B and 2. All survivors had relief of jaundice and pruritis after bypass. Complications occurred in 25 patients (45%). Preoperative transhepatic biliary drainage, performed in 14 patients prior to referral, was associated with a higher incidence of contaminated bile, greater operative blood loss, and postoperative biliary leak that was less likely to resolve spontaneously. Median survival in patients with cholangiocarcinoma (groups 1A and 1B) was 52 weeks and was unaffected by the type of bypass performed. By contrast, median survival in patients with gallbladder cancer (group 3) was 20 weeks; all but 3 died within 32 weeks of surgery. In patients with cholangiocarcinoma, the 1-year bypass patency was 80% in group 1A (segment III bypass) and 60% in group 1B (right sectoral hepatic duct bypass). Overall, there were 9 late bypass failures (18%) requiring reintervention. Conclusions: Intrahepatic biliary-enteric bypass effectively relieves symptoms due to malignant hilar obstruction. In patients with cholangiocarcinoma, segment III bypass provides excellent palliation with relatively few late complications and can be performed with minimal morbidity and mortality. Bypass to the right sectoral hepatic ducts, on the other hand, is associated with significant procedure-related morbidity and mortality and more late complications. Patients with gallbladder cancer, because of their poor survival, are probably better palliated by percutaneous biliary stenting.
Central nervous system relapse in acute promyelocytic leukemia: a single institution experience.

Acute promyelocytic leukemia (APL) is characterized molecularly by the PML–RARA rearrangement resulting from translocation t(15;17)(q24.1;q21.1) and clinically by a constellation of findings which ...
Upregulation of the HLH Id gene family in neural progenitors and glial cells of the rat spinal cord following contusion injury

Spinal cord injury (SCI) leads to a complex sequence of cellular responses, including astrocyte activation, oligodendrocyte death, and ependymal cell proliferation. Inhibitors of DNA binding (Id1, Id2, Id3) belong to a helix-loop-helix (HLH) gene family. Id genes have been implicated in playing a vital role in the proliferation of many cell types, including astrocytes and myoblasts. In the present study, the expression of Id family members in spinal cord after contusion injury was investigated by in situ hybridization. Id1, Id2, and Id3 mRNA expression was upregulated 5 mm rostral and caudal to the lesion center, and reached maximal levels 3 days after SCI. In addition, cell populations expressing Id1, Id2, and Id3 mRNA were maximally increased 3 days after SCI. The increase in Id2 and Id3 mRNA expression and Id2 and Id3 mRNA+ cells was still observed at 8 days. The Id mRNA expressing cells were phenotyped by combining immunostaining of cell-specific markers with in situ hybridization. Glial fibrillary acidic protein (GFAP)+ astrocytes were found to express all three Id mRNA, whereas S-100α+ astrocytes only expressed high levels of Id2 and Id3 mRNA. Cells having a neural progenitor morphology and the marker nestin appeared after SCI and they expressed Id1, Id2, and Id3 mRNA. Interestingly, some Rip+ oligodendrocytes located in the areas close to the central canal expressed Id3 mRNA after injury. In conclusion, Id genes are upregulated in a time-dependent manner in astrocytes, oligodendrocytes, and neural progenitor subpopulations after SCI, suggesting that they play major roles in cellular responses following SCI. J Neurosci. Res. 66:1161–1172, 2001. © 2001 Wiley-Liss, Inc.
π, π-allyl, and trimethylenemethane complexes derived from isobutylene adsorption on oxygen-activated Ag(110)

Abstract In this work the use of atomic oxygen on Ag(110) to synthesize two unusual intermediates, π-2-methylallyl CH 3 C(CH 2 ) 2(a) and trimethylenemethane C(CH 2 ) 3(a) , was investigated. Isobutylene (2-methylpropene) (CH 3 ) 2 CCH 2 adsorbs weakly, without reaction on clean Ag(110) held at 115 K, desorbing from two overlapping states with binding energies of 9.0 kcal mol −1 (37.9 kJ mol −1 ) and 11.5 kcal mol −1 (48.1 kJ mol −1 ), respectively. No multilayer formation is observed at surface temperatures of ⩾ 115 K. Co-adsorption of isobutylene and atomic oxygen on Ag(110) results in C-H bond activation via an acid-base mechanism, a reaction pathway which has been observed previously for acidic alkenes. Surface hydroxyl groups are formed at temperatures as low as 115 K. Although the major products are CO 2(g) and h 2 o (g) , a small amount of (CH 3 ) 2 CCH 2(g) evolves near 310 K. Eviden for the formation of co-adsorbed π-2-methylallyl (CH 3 )C(CH 2 ) 2(a) and trimethylenemethane C(CH 2 ) 3(a) was obtained by the combined use of temperature-programmed reaction spectroscopy (TPRS) and electron energy loss spectroscopy (EELS).