cssi/SciSciGPT-SciSciNet huggingface dataset:
Identifying critical regions for spike propagation in axon segments

Morphological reconstructions of axon segments reveal the abundance of geometrical ultrastructures that can dramatically affect the propagation of Action Potentials (AP). Moreover, deformations and swellings in axons resulting from brain traumas are associated to many neural dysfunctions and disorders. Our aim is to develop a computational framework to distinguish between geometrical enlargements that lead to minor changes in propagation from those that result in critical phenomenon such as reflection or blockage of the original traveling spike. We use a few geometrical parameters to model a prototypical shaft enlargement and explore the parameter space characterizing all possible propagation regimes and dynamics in an unmylienated AP model. Contrary to earlier notions that large diameter increases mostly lead to blocking, we demonstrate transmission is stable provided the geometrical changes occur in a slow manner. Our method also identifies a narrow range of parameters leading to a reflection regime. The distinction between these three regimes can be evaluated by a simple function of the geometrical parameters inferred through numerical simulations. We suggest that evaluating this function along axon segments can detect regions most susceptible to (i) transmission failure due to perturbations, (ii) structural plasticity, (iii) critical swellings caused by brain traumas and/or (iv) neurological disorders associated with the break down of spike train propagation.
800-5 Improving Accuracy of Ultrafast Computed Tomography in the Detection of Angiographically Significant Coronary Artery Disease

In differentiating coronary calcium from artifact by ultrafast computed tomography (UFCT), many different thresholds have been proposed. UFCT has demonstrated a high sensitivity and only modest specificity to detect coronary calcifications when compared to angiography. The Agatston method is most widely used today, utilizing a minimum CT number of 130 Hounsfield units (HU). In an attempt to improve specificity without markedly reducing sensitivity, we evaluated 272 coronary vessels from 68 patients with angiography and UFCT coronary scanning. All patients underwent coronary angiography for clinical indications, and had UFCT scanning done within three months of the angiogram. A blinded reader evaluated all the UFCT scans. We then varied the minimum CT number to assess whether 130 HU was truly the best threshold. Sensitivity, specificity and accuracy for different thresholds are listed. Threshold 130 HU 150 HU 170 HU 200 HU Sensitivity 95% 92% 89% 87% Specificity 65% 72% 75% 78% Accuracy 72% 77% 78% 79% The results above indicate that 130 HU is too low a threshold to maximize accuracy of this test when compared with angiography. Sensitivity is reduced as the threshold is improved, however this result is not significant (p = 0.61). The improved specificity from 130 to 150 represents a significant improvement (p l 0.0001), although a larger study must be performed before widespread use of this new threshold is employed.
Depth cue interaction in telepresence and simulated telemanipulation

We examined the contribution of two important depth cues, occlusion and disparity, on the performance of a simulated telerobotic task. We have simulated a three-axis tracking task that is viewed under four different levels of realism. We hoped to determine if the combined presentation of the depth cues has a more beneficial effect on performance than either depth cue presented singularly. Results showed similar performance improvements with the presentation of occlusion or disparity individually. When both cues were present together, a somewhat larger performance improvement was measured.
The relaxed exciton in alkali halide crystals

Abstract It is argued that an ionic crystal, upon excitation into an exciton state, should undergo a relaxation process in which the final state, before emission, consists of a Vk center plus a bound electron. It is also shown that, because of lattice relaxation, the occurrence of photoconductivity in the shoulder region does not necessarily imply the onset of band-to-band transitions.
Tool use by naked mole-rats

Naked mole-rats (Heterocephalus glaber, Rodentia: Bathyergidae) excavate extensive subterranean burrows with their procumbent incisors. Captive individuals often place a wood shaving or tuber husk behind their incisor teeth and in front of their lips and molar teeth while gnawing on substrates that yield fine particulate debris. This oral barrier may prevent choking or aspiration of foreign material. Consistent use of tools has rarely been reported in rodents.
Finite-wave-vector electromagnetic response of fractional quantized Hall states.

A fractional quantized Hall state with filling fraction \ensuremath{\nu}=p/(2mp+1) can be modeled as an integer quantized Hall state of transformed fermions, interacting with a Chern-Simons field. The electromagnetic response function for these states at arbitrary frequency and wave vector can be calculated using a semiclassical approximation or the random-phase approximation. However, such calculations do not properly take into account the large effective-mass renormalization which is present in the Chern-Simons theory. We show how the mass renormalization can be incorporated in a calculation of the response function within a Landau-Fermi-liquid theory approach such that Kohn's theorem and the f-sum rules are properly satisfied. We present results of such calculations.
Isolation of a developmentally‐regulated expressed sequence tag from bladder tissue using the mRNA differential display

In order to gain insight into the molecular and cellular events that govern the structural and the functional properties in developing organs, we have conducted a study to identify genes that have a temporally-restricted expression in the bladder wall during fetal development. We utilized the mRNA differential display technique and compared the pattern of gene expression during the first, the second and the third trimester of gestation. We cloned and sequenced a cDNA fragment (bld-10) which was expressed during the second and third trimester but consistently absent during the first trimester. The bld-10 sequence is not related to any known gene in the GenBank database but has significant homology (89%) with human expressed sequence tag (EST) that has been cloned from human fetal heart and brain libraries. When used in Northern-blot hybridization as a probe, the fragment bld-10 generates two hybridization signals of 3.1 and 4.0 kb, that are minimally expressed during the first trimester of gestation and upregulated in the second and third trimester. Differential expression of this gene may be responsible for some of the profound changes which occur during organ development.
Nearest-neighbor doublets in protein-coding regions of MS2 RNA.

“Nearest neighbor” base pairs (“doublets”) in the protein-coding regions of MS2 RNA have been tabulated with respect to their positions in the first two bases of amino acid codons, in the second two bases, or paired by contact between adjoining codons. Considerable variation is evident between numbers of doublets in each of these three possible positions, but the totals of each of the 16 doublets in the coding regions of the MS2 RNA molecule show much less varation. Compilations of doublets in nucleic acid strands have no predictive value for the amino acid composition of proteins coded by such strands.
Changes in methylation of tissue cultured soybean cells detected by digestion with the restriction enzymes HpaII and MspI.

Each of the tandemly arranged 5S RNA genes of soybean contain two CCGG sites which, if unmethylated, can be digested by both MspI and HpaII. Methylation of the internal cytosine (CmeCGG) prevents digestion by HpaII but allows digestions by MspI.
Rheological Characterization of Skim Milk Stabilized with Carrageenan at High Temperatures

Superpositioning principles were applied twice to model temperature (25 to 125 8 88 8C) and concentration (0.005 to 0.040% w/w) effects on skim milk and carrageenan solutions. Samples were analyzed using a controlled stress rheometer equipped with a pressurized sealed cell, permitting measurements well above standard boiling conditions. Individual samples were sheared between 10 and 160 s -1 , and predictive equations were developed to predict Newtonian viscosity as a function of temperature and carrageenan concentration. The superpositioning technique coupled with advancements in rheological instrumentation permits high temperature measurements and
Effects of caudate nuclear or frontal cortical ablation in neonatal kittens or adult cats on the spontaneous firing of forebrain neurons.

Abstract In this paper we have determined the long-lasting consequences of caudate and frontal cortical lesions on spontaneous neuronal firing. Lesions were made both in neonatal and adult cats. All recordings were made in adults. Qualitatively, the effects of the caudate ablations were similar whether they had been carried out in kittens or in adult cats. Caudate lesions produced long-lasting (≥ 1 year) decreases in the spontaneous firing of cortical neurons. These changes were more pronounced when made in neonates than in adults. The distributions of mean interspike intervals were also altered by these caudate lesions in the pallidum and in the ventral lateral nucleus of the thalamus. Again these effects were more marked if the animals were lesioned as neonates than as adults. Frontal cortical lesions inflicted upon adult cats produced more widespread changes in spontaneous firing rates than similar lesions made in neonates. In both groups frontal lesions slowed spontaneous firing and changed the distributions of mean interspike intervals of caudate neurons. These effects were long-lasting (≥ 1 year in neonatally-ablated animals). Cortical lesions made in adult cats markedly altered thalamic and pallidal spontaneous activity. Similar lesions made in neonates produced relatively small changes in thalamic and pallidal activity.
Heterogeneous activation of peroxymonosulfate by supported cobalt catalysts for the degradation of 2,4-dichlorophenol in water: The effect of support, cobalt precursor, and UV radiation

Abstract In order to generate sulfate radicals (SRs) as oxidizing species for the degradation of 2,4-dichlorophenol (2,4-DCP) in water, we explored heterogeneous activation of peroxymonosulfate (PMS) by supported cobalt catalysts. More attention was given to the effect of support materials (Al2O3, SiO2, TiO2) and cobalt precursors (Co(NO3)2, CoCl2, CoSO4) on cobalt–support interaction, cobalt leaching, and reactivity of the catalysts. Especially, the feasibility of simultaneous generation of SRs and hydroxyl radicals (HRs) in PMS-Co/TiO2 systems was first studied under ultraviolet (UV) radiation. Much lower cobalt leaching was observed in Co/Al2O3 and Co/TiO2 systems than that of Co/SiO2 most probably due to their relatively strong cobalt-support interaction. Co/TiO2 catalyst prepared with Co(NO3)2, compared to CoCl2 or CoSO4 (where Cl− and SO42−, respectively, were not completely removed upon heat treatment at 500 °C), showed strong cobalt–support interaction, and thereby exhibited negligible cobalt leaching. Under UV radiation, Co/TiO2 at Co/Ti molar ratio of 0.001 showed significant improvement in the degradation of 2,4-DCP due to HRs. The effective generation of HRs in the system can be explained with Co(III)-mediated charge transfer from the photoinduced electrons to PMS, inducing facilitation of photoinduced electron-hole separation. However, high cobalt loading (i.e., Co/Ti molar ratio of 0.1) on TiO2 surface exhibited negligible enhancement of 2,4-DCP transformation under UV radiation since the penetration of UV light to TiO2 was prohibited by the cobalt.
Reshapable physical modulator for intensity modulated radiation therapy.

A new method of generating beam intensity modulation filters for intensity modulated radiation therapy(IMRT) is presented. The modulator was based on a reshapable material, which is not compressible but can be deformed under pressure. A two-dimensional (2D) piston array was used to repeatedly shape the attenuating material. The material is a mixture of tungstenpowder and a silicon-based binder. The linear attenuation coefficient of the material was measured to be 0.409 cm−1 for a 6 MV x-ray beam. The maximum thickness of the physical modulator is 10.2 cm, allowing a transmission of 1.5%. A 16×16 square piston array was used to generate a depth pattern in the deformable attenuating material. Each piston has a cross section of 6.37×6.37 mm 2 . The modulator was placed 65 cm from the radiation source of the linear accelerator in the position of the shielding tray. At this position, each piston projects to a 1.0×1.0 cm 2 area at the isocenter, giving a treatment field of 16×16 cm 2 . The percent depth dose curve and output factor measurement show a slight beam hardening and a 1%–4% increase in scatter fraction when 2.2–4.4 cm uniform thickness filters are in the beam. The surfacedose was decreased with the filter in the beam. Ion chamber and verification films were used to verify the entrance dose. The measured absolute and relative doses were compared with the calculated dose. The agreement of measurements and calculations is within 3%. In order to verify the spatial modulation of dose, 1-D dose profiles were obtained using dose calculations. Calculated and measured profiles were compared. The 20%–80% penumbra of the modulator was measured to be 5.5–10 mm. The results show that a physical modulator formed using a 16×16 piston array and a deformable attenuation material can provide intensity modulation for IMRT comparable with those provided by currently available commercial MLC techniques.
Conducting polymers as substrates for surface-mounted molecular devices

Abstract Thin films of poly(3,4-diethoxythiophene), PEDOT, were prepared by vacuum sublimation/polymerization of 2,5-dibromo-3,4-ethylenedioxythiophene onto freshly cleaved mica. AFM studies show that the films are exceptionally smooth and contain both highly crystalline and amorphous regions. Exposure of the film to polar solvents for one hour causes an increase in the surface roughness, while exposure to non-polar solvents or thermal annealing decreases surface roughness. Ary thiols linked to diazo dye labels can be covalently bound to the films by simple exposure in dilute methylene chloride solutions. This provides a convenient way to functionalize PEDOT surfaces with molecular devices.
Parent and child views of parent-child relationship qualities and resilient outcomes among urban children.

Separate in-depth interviews were conducted with two groups of highly stressed 4th-6th grade urban children classified as stress-affected (SA) and stress-resilient (SR), and their parents. Judges identified interview items reflecting three components of a good parent-child relationship, i.e. positive parental attitudes, involvement and guidance. SR parents and children scored higher than their SA counterparts on all three relational dimensions. Additionally, SR parent-child dyads had more congruent views of their relationship than SA dyads. These findings suggest that positive parent-child relationship qualities play an important protective role that favors resilient outcomes, at ages 10-12, among children who have experienced major life stress.
Hybridization among Crassostrea species: a review

Abstract Numerous attempts at hybridization in the genus Crassostrea have been reported. Most suffer from one or more of the following: (1) ambiguities in the classification of oysters; (2) contamination of experimental cultures by extraneous gametes or larvae; (3) the absence of control experiments for assessing the quality of gametes as well as larval viabilities; (4) the absence of genetic confirmation of hybrid status. We conclude that to date there is no unequivocal evidence for the existence of viable interspecific hybrids among Crassostrea species. Examples of taxonomic ambiguities that cloud interpretation of hybridization experiments include the frequent misclassification of the Kumamoto oyster ( C. sikamea ) as the Pacific oyster ( C. gigas ), the probably unjustified distinction between C. gigas and the Portuguese oyster C. angulata , and the lumping of C. iredalei with C. rivularis . Low-level contamination of cultures is a common occurrence that may account for many reports of successful hybridization. Experimental controls are essential to properly assess gamete quality and zygote growth and survival, yet are often not included. Finally, few reports provide genetic confirmation that the zygotes produced are actually hybrids. To date, most genetic analyses have demonstrated that putative interspecific hybrid oysters were not hybrids. Use of adequate controls and genetic analysis of parents and offspring are essential to hybridization experiments, and are demonstrated elsewhere.
Coupled mode analysis of crosstalk in multicore fiber with random perturbations

A simple, general crosstalk formula is derived for multicore fibers with random perturbations using coupled mode theory. Analytical crosstalk expressions under exponential and Gaussian correlation length distributions are presented. Experimental results agree well with theory.
Functional homodimeric glycoprotein hormones: implications for hormone action and evolution

Background:. Human chorionic gonadotropin (hCG), lutropin, follitropin, and thyrotropin act as alphabeta heterodimers to control reproduction and thyroid function. The alpha and beta subunits of these proteins are divided into three loops (alpha1, alpha2,alpha3; beta1,beta2,beta3) by cysteine knots and the heterodimer is stabilized by 20 beta-subunit residues wrapped around alpha2 like a seatbelt. Understanding how these hormones interact with their receptors, a matter of considerable dispute, would facilitate design of pro- and anti-fertility agents. Results:. By swapping alpha2 for beta2 and vice versa and, in some cases, adding an amino-terminal coiled-coil dimerization domain, we prepared homodimeric analogs that have the conformation found in each 'half' of hCG. Homodimers containing loops beta1,alpha2,beta3 and none, part, or all of the seatbelt stimulated signal transduction to the same extent as hCG, albeit with lower potency. Those containing alpha1,beta2,alpha3 were inactive. Conclusions:. The activities of homodimers containing the beta1,alpha2,beta3 groove exceed those of other minimized analogs more than 100-1000-fold, suggesting this portion of the hormone forms the major receptor contact. The discovery that glycoprotein hormone heterodimers can be converted to functional homodimers supports the proposal that this protein family evolved from an active homodimeric ancestor by gene duplication and acquisition of mutations to loop 2 that prevent homodimerization. This approach to protein minimization should be applicable to other proteins composed of architecturally related subunits, including those that might have arisen by gene duplication.
Affinity coelectrophoresis for dissecting protein-RNA domain-domain interactions in a tRNA synthetase system.

Abstract The class I methionyl tRNA synthetase has a conserved N-terminal nucleotide binding fold which contains the active site, and a largely non-conserved C-terminal anticodon binding domain. At the C-terminal end of the anticodon binding domain is a peptide which curls back into the N-terminal nucleotide binding fold near the active site. We showed that a mutation in this peptide disrupts aminoacylation and binding of a 7 base pair microhelix substrate based on the acceptor stem of tRNAfMet. The novel technique of affinity coelectrophoresis was applied to this system for the first time to determine dissociation constants of wild-type and mutant MetRS for small RNA substrates. A description and evaluation of this technique for measuring weak protein-nucleic acid interactions is presented here, in the context of the methionyl tRNA synthetase system.
Generalized binding phenomena in an allosteric macromolecule

A general macromolecular partition function is developed in terms of chemical ligand activity, temperature and pressure for systems described by an array of species which are characterized by their state of allosteric conformation and ligand stoichiometry. The effects of chemical ligand binding, enthalpy change, and volume change are treated in a parallel manner. From a broad viewpoint all of these effects can be regarded as specific cases of generalized binding phenomena. This approach provides a general method for analyzing calorimetric and ligand binding experiments. Several applications are given: (1) Thermal scanning data for tRNAphe (P.L. Privalov and V.V. Filimonov, J. Mol. Biol. 122 (1978) 447) are shown to fit a general model with six conformational states. By application of linkage theory it is shown that sodium chloride is expelled as the molecule denatures. (2) The results of calorimetric titrations on the arabinose binding protein (H. Fukada, J.M. Sturtevant and F.A. Quiocho, J. Mol. Biol. 258 (1983) 13193) are shown to fit a simple two-state allosteric model. (3) A thermal binding curve is simulated for an unusual respiratory protein, trout I hemoglobin (B.G. Barisas and S.J. Gill, Biophys. Chem. 9 (1979) 235), in order to illustrate both the similarities and differences between enthalpy and chemical ligand binding processes.
The Robert Wood Johnson Foundation Commission on Medical Education. The sciences of medical practice, summary report.

THE Robert Wood Johnson Foundation Commission on Medical Education began its study in February 1990, in response to the perception of many medical educators that medical student education needed fundamental change. Results of a Louis Harris survey of US medical educators in 1989 clearly indicated that "deans, department chairmen, and clinical faculty overwhelmingly endorsed the need for 'fundamental changes' or 'thorough reform' in medical student education." 1 Faculty, students, and practicing physicians share concern about the science education students receive in medical school and the fact that they are too often not engaged by the science components of their education. At the same time, US medical schools have assembled the richest source of scientific talent in history; their scientists play a leading role in the evolution of a new biology created by advances in molecular medicine that cross all departmental and disciplinary lines and require a renewed emphasis on understanding
Water defluoridation using a nanostructured diatom–ZrO2 composite synthesized from algal Biomass

Frustules or the rigid amorphous silica cell wall of unicellular, photosynthetic microalgae with unique porous architecture has been used to synthesize a composite by immobilizing ZrO2 on its surface and in the pores. This was effective in water defluoridation. The average diameter of the composite was 80±2 nm and surface area was 140 m(2)/g. The adsorption isotherms followed both Langmuir and Freundlich models, and the composite was regenerable. Adsorption kinetics followed second order model and the adsorption capacity was as high as 11.32 mg/g, while the Langmuir maximum adsorption capacity (q(m)) reached 15.53 mg/g. The research findings highlight the potential of diatoms as hosts for nanomaterials for use in water treatment.
“Cowboys and Indians” Pedagogical Constructions and Interventions

A sorority and fraternity at the University of Denver recently held a “Cowboys and Indians” theme party. Reflecting from this event, I examine how it has shaped my students’ attitudes toward domina...
Assessment of Syntax after Adolescent Brain Injury: Effects of Memory on Test Performance.

In this study, we investigated the influence of working memory load on performance of a task designed to measure receptive syntax ability. Subjects were 6 brain-injured adolescents and 6 hospitaliz...
Engineers turn to e-learning

Learning online is one of the strongest currents in higher education, as the working engineer in particular is discovering. This paper details how, in the coming years, technological advances, such as wireless networking, will undoubtedly help make e-learning more attractive. And as high-speed, broadband Internet connections become the norm, more real-time, interactive uses of the Web will appear in online-learning classes.
Examination of the toxicity of several protein toxins of plant origin using bovine pulmonary endothelial cells

The bovine pulmonary endothelial (BPE) cell line was examined as a model to study the toxicity of ricin and abrin toxins currently under investigation. The BPE cell line was examined because ricin has been shown to bind to endothelial cells. Cell viability was assessed using several different biochemical parameters including growth (DNA by binding of gentian violet stain), mitochondrial function (succinate dehydrogenase activity) using MTT and lysosomal integrity (neutral red retention assay). In order to compare toxicities and investigate potential protective compounds, concentrations of toxins causing death of 50% and 70% of the (control) cell population (LC50 and LC70, respectively) were determined. It is concluded that while ricin and abrin share a common mechanism of action ricin is slightly less toxic than abrin. BPE cells are a good model for future mechanistic studies and particularly for initial phase screening of potentially therapeutic compounds. Carbohydrates were used in an attempt to examine which receptor types were involved in the binding and uptake of ricin and abrin by the cell line. It was found that only high concentrations of galactose prevented lethality while mannose apparently had no effect. Furthermore, the molar excess of carbohydrate to toxin required in order to achieve protection indicated that this would be an impractical approach to adopt in vivo.
Specificity in the participation of connexin proteins in flow-induced endothelial gap junction communication.

Endothelial cell (EC) dysfunction and atherosclerotic plaque formation coincide with human circulatory regions where blood flow is altered (disturbed). In areas of undisturbed uniform blood flow, including the majority of the vasculature, the vessel wall is relatively atherosclerotic lesion-resistant with normal endothelium. The molecular mechanisms of blood flow regulation of EC function and atherogenesis are unclear. We hypothesize that EC dysfunction potentiating atherosclerosis is related to disturbed flow (DF)-induced EC gap junctional intercellular communication (GJIC) changes via the gap junction connexin (Cx) 37, 40, and 43 proteins, which are involved in EC proliferation and vasoactivity that are known to be altered in atherosclerosis. We investigated human EC GJIC using an in vitro model of the hemodynamic features found in atherosclerotic-prone DF regions in vivo. Using dye transfer assays, Cx-specific mimetic peptide inhibitors, proliferation assays, and immunocytochemistry, we correlated functional GJIC via gap junction channels formed by hemichannels composed of the two most abundant endothelial Cx—Cx40 and Cx43—to EC proliferation and expression of vasoactive endothelial-type nitric oxide synthase (eNOS). We found that, in uniform flow conditions, substantial GJIC was conducted through gap junctions containing Cx40 hemichannels and correlated to a nonproliferative EC phenotype and membrane localization of eNOS, similar to physiological conditions. In DF, GJIC was largely attained through Cx43 hemichannel-containing gap junctions, EC phenotype was proliferative (attributed to loss of contact inhibition), and intracellular eNOS was more abundant than membrane eNOS, typical of atherosclerotic sites in vivo. This is the first in vitro study to demonstrate local hemodynamically defined Cx protein specificity in human EC GJIC with a potential role in endothelial dysfunction characteristic of early atherosclerosis.
Kinetic and mechanistic studies of photopolymerizations of acrylates in the presence of iniferters

In this particular study, the reaction mechanisms of bulk polymerization of acrylates in the presence of tetraethylthiuram disulfide (TED) are investigated using hexyl acrylate as a model acrylate. TED's presence impacts the termination mechanisms of the acrylate polymerization by two pathways: (1) dissociation of TED to generate dithiocarbamate radicals, which could terminate the acrylic radicals, and (2) chain transfer to TED. The impact of TED concentration as well as the initiation rate on the hexyl acrylate polymerization rate was investigated for polymerizations initiated by both UV and visible light. It was observed that for the polymerizations initiated by UV light, the initial polymerization rate (averaged between 5 and 20% conversion) scaled with the initiation rate by a power of 0.86 ± 0.02 at various concentrations of TED, and a power of 0.45 ± 0.05 for polymerizations in the absence of TED. The initial polymerization rate exhibited a near inverse-linear relationship with the concentration of TED, with the order of dependence ranging from -0.96 ± 0.13 to -1.00± 0.14. Thus, it was found that chain transfer to TED appears to contribute significantly to the termination mechanisms in the polymerization of acrylates. It was observed that TED does not exhibit any absorbance in the visible range (400-500 nm), and hence, the dissociation of TED was eliminated in the polymerizations conducted by visible light. For these polymerizations initiated by visible light, the initial polymerization rate scaled with the initiation rate by a power of 0.84 ± 0.04 to 0.95 ± 0.05 at various TED concentrations ranging from 0.1 to 0.5 wt %. It was also observed that at a light intensity of 25 mW/cm 2 , the log-log plot of the initial polymerization rate as a function of TED concentration exhibited a slope of -1.19 ± 0.03. Thus, the dependence of polymerization rate on the TED concentration was observed to be greater than the expected inverse-linear relationship because of the dependence of the termination kinetic constant on the concentration of TED. Furthermore, it was shown that chain-transfer to TED is the dominant mechanism relative to the dissociation of TED to generate dithiocarbamate radicals, and it appears to contribute significantly to the termination reactions for both polymerizations.
Triplet-sensitized reactions of some main chain liquid-crystalline polyaryl cinnamates

Thin films of a liquid crystalline polyaryl cinnamate have been irradiated at (lambda) > 400 nm in the presence of ketocoumarin triplet sensitizers. The aryl cinnamate chromophore disappears upon irradiation with concomitant loss of solubility attributed to cross-linking by interchain cyclobutane photoproduct formation. Competing loss of sensitizer absorption also occurs during irradiation. Up to ca. 80% of the aryl cinnamate chromophores in amorphous films can be destroyed using high weight percentages (>= 5%) of sensitizer. At low concentrations of sensitizer (0.5 wt.%), approximately 80 cinnamate chromophores are photolyzed for each sensitizer molecule initially present, despite the competing photolysis of sensitizer during the course of irradiation. The ketocoumarins are insoluble in the glassy (frozen) nematic films of the polymer and thus are ineffective in sensitizing photolysis in this more organized phase.
Weight change in infants with a functionally univentricular heart: from surgical intervention to hospital discharge

ObjectiveThe purpose of this study was to assess the pattern of weight change from surgical intervention to home discharge and to determine predictors of poor growth in this population of infants with congenital cardiac disease.MethodsNeonates with functionally univentricular physiology enrolled in a prospective cohort study examining growth between March, 2003 and May, 2007 were included. Weights were collected at birth, before surgical intervention, and at hospital discharge. In addition, retrospective echocardiographic data and data about post-operative complications were reviewed. Primary outcome variables were weight-for-age z-score at discharge and change in weight-for-age z-score between surgery and discharge.ResultsA total of 61 infants met the inclusion criteria. The mean change in weight-for-age z-score between surgery and hospital discharge was minus 1.5 plus or minus 0.8. Bivariate analysis revealed a significant difference in weight-for-age z-score between infants who were discharged on oral feeds, minus 1.1 plus or minus 0.8 compared to infants with feeding device support minus 1.7 plus or minus 0.7, p-value equal to 0.01. Lower weight-for-age z-score at birth, presence of moderate or greater atrioventricular valve regurgitation, post-operative ventilation time, and placement of an additional central venous line were associated with 60% of the variance in weight-for-age z-score change.ConclusionNeonates undergoing staged surgical repair for univentricular physiology are at significant risk for growth failure between surgery and hospital discharge. Haemodynamically significant atrioventricular valve regurgitation and a complex post-operative course were risk factors for poor post-operative weight gain. Feeding device support appears to be insufficient to ensure adequate weight gain during post-operative hospitalisation.
Antiviral Activities of 9-R-2-Phosphonomethoxypropyl Adenine (PMPA) and Bis(isopropyloxymethylcarbonyl)PMPA against Various Drug-Resistant Human Immunodeficiency Virus Strains

9-R-2-Phosphonomethoxypropyl adenine (PMPA) is an acyclic nucleoside phosphonate analog that has demonstrated efficacy against human immunodeficiency virus (HIV). We recently described the synthesis, metabolism, and biological activities of bis(isopropyloxymethylcarbonyl)PMPA [bis(poc)PMPA] as an orally bioavailable prodrug for PMPA. Among a large panel of drug-resistant HIV type 1 variants, only the K65R virus was resistant to PMPA. K65R virus also showed reduced susceptibility to bis(poc)PMPA, although the prodrug could still inhibit these viruses at submicromolar, nontoxic concentrations. Among a panel of seven primary clinical isolates from patients with diverse treatment histories, only one isolate showed reduced susceptibility to PMPA and was found to carry three mutations (M41L, T69N, R73K) in its reverse transcriptase catalytic domain.
175 Toward an Optical Biogeography of the Oceans

Remote sensing of ocean color has revolutionized our ability to understand the processes leading to the observed distribution of different taxa in marine waters. Many scientists in the remote sensing and optics community are working toward retrieval of species distributions using ocean color measurements to derive the concentration of recognized chemotaxonomic markers. In this talk, I work toward an optical biogeography of the ocean by viewing the optical environment as a selection regime that creates biogeographic boundaries or “optical fences” defining the distribution of taxa with different light harvesting systems and/or different physiologies. Working primarily with data from a wide range of tropical, sub-tropical, and warm temperate coastal margins, I show that there is a close association between the distribution of different spectral forms of PE-containing picocyanobacteria and the optical properties of the water masses in which they are found. This pattern also appears to be reflected in the distribution some dinoflagellate taxa, indicating that the optical environment encompasses a range of key niche parameters that, in turn, determine the biogeographic distribution of species.
Near optimality of Chebyshev interpolation for elementary function computations

A common practice for computing an elementary transcendental function in an libm implementation nowadays has two phases: reductions of input arguments to fall into a tiny interval and polynomial approximations for the function within the interval. Typically, the interval is made tiny enough so that polynomials of very high degree aren't required for accurate approximations. Often, approximating polynomials as such are taken to be the best polynomials or any others such as the Chebyshev interpolating polynomials. The best polynomial of degree -n has the property that the biggest difference between it and the function is smallest among all possible polynomials of degrees no higher than n. Thus, it is natural to choose the best polynomials over others. In this paper, it is proven that the best polynomial can only be more accurate by at most a fractional bit than the Chebyshev interpolating polynomial of the same degree in computing elementary functions or, in other words, the Chebyshev interpolating polynomials will do just as well as the best polynomials. Similar results were obtained in 1967 by Powell who, however, did not target elementary function computations in particular and placed no assumption on the function and, remarkably, whose results imply accuracy differences of no more than 2 to 3 bits.
Feedback in Sequential Machine Realizations

In this paper we study feedback in sequential machines that are implemented with trigger or set-reset flip-flop memory elements. A method is given for determining when a machine can be implemented with either trigger or set?reset flip-flop memory elements where the feedback in the machine is given by a Boolean function f. Several results are presented that compare the feedback when a machine is implemented with different memory elements. It is shown that if a sequential machine can be implemented with unit delay memory elements with feedback function f, then it can be realized with set-reset flip-flop with the same feedback function f. For completely specified machines, it is shown that if a machine implemented with trigger flip-flop has no feedback, then the some machine implemented with unit delays will have feedback. Conversely, if an implementation with unit delays has no feedback, then an implementation with trigger flip-flops will have feedback.
IMMUNITY AND INFERTILITY: A REVIEW

A review of studies conducted on the possible influence on reproductive fertility that may be imposed by immune mechanisms is presented. The major topics discussed include: 1) immunological aspermatogenesis and orchitis 2) sperm antibodies in humans and 3) reduction of fertility by means of immunization. In all these categories there are more-or less clearcut relationships to contraceptive possibilities or at least to the clarification of immunological principles that may later be applied to contraceptive applications. The first significant steps in the study of autoantibodies and autoimmunity to the testis and its components were taken in 1951 and 1953 on guinea pigs in the work by Voisin Delaunay and Barber and by Freund Lipton and Thompson. There have been a number of reports on the occurrence of a spermagglutinating activity in the serum taken from certain men and women. Various workers have attributed this activity to the existence of specific antibodies against the sperm cells and have sought to correlate this phenomenon with unexplained sterility of the individual. In a number of studies on experimental animals a reduction of fertility in female animals that had been immunized with sperm or testicular material has been described by a number of workers. A few studies have been made on animals with regard to the effects of vasoligation in the stimulation of antibody formation. At the authors laboratory at the New York Medical College an investigation on human vas ligation was undertaken. Serum samples were taken before surgery and at various intervals afterwards to search for the possibility of antibody production against human spermatozoa. More than half the patients developed antibody activity. The findings were confirmed later in a study carried out by Ansbacher.
Crystal shape modeling and control in protein crystal growth

Proteins play a key role as therapeutics in a number of diseases and protein crystallization is a central activity in the pharmaceutical industry. Protein crystals, usually produced through a batch crystallization process, are desired to be of high quality, of desired shape, and within a narrow size and shape distribution range. Motivated by the above considerations, the present work focuses on the modeling and control of protein crystal shape. The model protein used for this work is the tetragonal hen egg white lysozyme. The growth of an individual lysozyme crystal is modeled via kinetic Monte Carlo (kMC) simulations comprising adsorption, desorption, and migration events on the (110) and (101) faces, which are assumed to be independent. The expressions for the rate equations for each event type are similar to those of Durbin and Feher (1991). Extensive testing of the system parameters indicates crossover behavior between the growth rates of the two faces [i.e., (110) and (101)], a fact that has also been observed experimentally. A nonlinear algebraic equation that relates the steady-state growth rate ratios between the (110) and (101) faces, the temperature and concentration, is derived from the kMC simulation data. This nonlinear equation is then utilized by a model predictive controller which regulates the protein crystal to desired shapes subject to manipulated input constraints. The proposed method is shown to successfully regulate protein crystal shape, ranging from equidimensional to more elongated type of structures, in the presence of arbitrary variations of the protein concentration.
Single-cell measurement of the levels and distributions of the phosphorelay components in a population of sporulating Bacillus subtilis cells

Upon nutrient starvation, the Gram-positive bacterium Bacillus subtilis switches from growth to sporulation by activating a multicomponent phosphorelay consisting of a major sensor histidine kinase (KinA), two phosphotransferases (Spo0F and Spo0B) and a response regulator (Spo0A). Although the primary sporulation signal(s) produced under starvation conditions is not known, it is believed that the reception of a signal(s) on the sensor kinase results in the activation of autophosphorylation of the enzyme. The phosphorylated kinase transfers the phosphate group to Spo0A via the phosphorelay and thus triggers sporulation. With a combination of quantitative immunoblot analysis, microscopy imaging and computational analysis, here we found that each of the phosphorelay components tested increased gradually over the period of sporulation, and that Spo0F was expressed in a more heterogeneous pattern than KinA and Spo0B in a sporulating cell population. We determined molecule numbers and concentrations of each phosphorelay component under physiological sporulation conditions at the single-cell level. Based on these results, we suggest that successful entry into the sporulation state is manifested by a certain critical level of each phosphorelay component, and thus that only a subpopulation achieves a sufficient intracellular quorum of the phosphorelay components to activate Spo0A and proceed successfully to the entry into sporulation.
Frequency enhanced digital AM radio

An all-digital AM radio with stereo decoding is discussed. Digital demodulation, filtering and decoding are implemented as well as digitally compensating for the less than ideal frequency response of the typical AM analog receiver front end. Although the resulting stereo signal is not as good as that produced by FM stereo radio, it is a very good quality stereo signal and a noticeable improvement over standard analog reception techniques. >
Treatment of intermittent claudication with pentoxifylline and cilostazol

The pathophysiology of intermittent claudication (IC) and the role of pentoxifylline and cilostazol for treating IC are discussed. IC, a result of inadequate blood flow to the musculature, is the primary symptom of occlusive peripheral vascular disease (PVD). Patients with IC often have a decreased quality of life because of mobility limitations. PVD is a sign of generalized atherosclerosis and increases the risk of cardiac morbidity and mortality. Smoking, hypertension, diabetes mellitus, and increasing age may hasten the progression of PVD. Strategies for treating IC are aimed at improving symptoms and reducing the progression of atherosclerosis and include risk-factor modification, exercise, and antiplatelet therapy. Cilostazol and pentoxifylline are the only two drugs with FDA-approved labeling for use in treating IC. Both drugs have been shown to increase pain-free walking time and total distance walked, although there is some conflicting evidence for pentoxifylline. Cilostazol and pentoxi-fylline are fairly well tolerated; the most common adverse effects involve the gastrointestinal tract and central nervous system. Inhibitors of cytochrome P-450 isoenzymes 3A4 and 2C19 should be used cautiously in patients taking cilostazol, and this drug is contraindicated in patients with congestive heart failure. Cilostazol is more costly than pentoxifylline. Initiation of therapy with either pentoxifylline or cilostazol may be reasonable if risk-factor modifications, lifestyle changes, and antiplatelet therapy are not effective. The mainstays of therapy for IC are risk-factor modification, exercise, and antiplatelet therapy. If these prove inadequate, treatment with pentoxifylline or cilostazol may be reasonable.
Site-specific positive margins at radical prostatectomy: Assessing cancer-control benefits of wide excision of the neurovascular bundle on a side with cancer on biopsy

OBJECTIVE To determine the potential risk of biopsy-selected nerve-sparing surgery based on the findings of site-specific extracapsular extension (ECE) and positive surgical margins (PSMs) in the area of the neurovascular bundle in radical prostatectomy specimens. PATIENTS AND METHODS Controlling for surgical technique and pathological interpretation, 221 consecutive patients had their neurovascular bundles removed on the side with a positive biopsy. The surgical specimens were reviewed for ECE and PSM status, specifically in the area of the neurovascular bundle, from apex to base. RESULTS Of the 221 patients, 38% had ECE and 43 (20%) had a PSM in the area of the neurovascular bundle. This equates to a ratio of 51% for PSM/ECE. An additional 42 men (18%) had ECE with negative margins, but would have been at potential risk for PSMs if the neurovascular bundle had been preserved. CONCLUSION Preserving the neurovascular bundle on the side with a positive biopsy could result in a significantly greater incidence of PSM than with wide excision. Optimizing cancer control may require excision of the neurovascular bundle on a side known to have cancer on biopsy. In future site-specific analyses, the PSM/ECE ratio could be used as a marker comparing cancer-control outcomes from studies with differing technical approaches and indications for nerve-sparing surgery.