cssi/SciSciGPT-SciSciNet huggingface dataset:
The Twists and Turns of Enzyme Function

We learn metabolic biochemistry largely as a series of pathways such as glycolysis, the citric acid cycle, the histidine biosynthetic pathway, etc., where each step in the pathway is catalyzed by a specific enzyme. Exceptions to this are known and are increasing. In the work by Kozmin et al. (12) directed at determining the pathway that allows Escherichia coli cells to protect themselves against toxic 6-N-hydroxylaminopurine (HAP), they have demonstrated that only the CysJ component of the sulfite reductase complex (CysJ8CysI4 or α8β4) serves along with YcbX in the reduction of HAP back to nontoxic adenine that can enter back into metabolism via a purine-salvaging pathway. Before this work, YcbX was predicted to be only a [Fe2-S2] cluster-containing protein. Their work not only confirms the function of the ycbX open reading frame in E. coli but shows that this enzyme also requires the molybdenum cofactor (MoCo) to function. The work thus demonstrates that the CysJ portion of the sulfite reductase complex can have multiple roles in cells by supplying reducing equivalents to other enzymes. This raises the possibility that other examples of redox carrier proteins functioning with multiple acceptor proteins are waiting to be discovered. This observation of multiple functions is not to be confused with so-called moonlighting enzymes, where more than one function is found in a single polypeptide chain (9), since here the enzyme is still performing the same function. Another protein implicated in this detoxification of hydroxylamines is YiiM, which the authors show also to be a MoCo-dependent enzyme but one that is not reduced by CysJ. Thus, the work also indicates the presence of two previously unknown MoCo-dependent enzymes.
Streptozotocin-induced diabetes and the rat periodontium: decreased relative collagen production.

Abstract This is the first study concerning the extent to which relative collagen production (RCP) in rat periodontal tissues is affected by diabetes. Determination of RCP, rather than individual production rates for collagen or for non-collagen protein, was deemed necessary because saturation of all proline pools in tissues of diabetics (and non-diabetic controls) was not achieved. Such non-saturation occurred despite the injection of a poolexpanding dose of proline (400–1150 mg/rat), non-saturation indicated by the lesser specific radioactivity (S.R.) of free- [3H]proline in tissues than that of the injected solution. RCP was decreased in five periodontal tissues (incisor and molar gingiva, incisor and molar periodontal ligament, antemolar palatal mucosa) and in skin. Diabetes-decreased RCP seems to result from decreased collagen synthesis and increased intracellular degradation, although some evidence is presented for increased extracellular degradation of recently secreted collagen.
King Hu and Run Run Shaw: the clash of two cinema legends

ABSTRACTKing Hu is revered as one of the most influential film-makers of Chinese cinema. Run Run Shaw is the legendary tycoon behind the renowned media kingdom Shaw Brothers. After Hu joined Shaw Brothers in 1958 as an actor, it was Shaw who offered Hu his first career opportunities to write and direct. But animosity and differences came between them to the extent that they would never collaborate again after making history with their groundbreaking success Da zui xia/Come Drink with Me (1966). This article chronicles King Hu's arduous yet invaluable tenure at the flourishing film studio operated by Run Run Shaw. It examines the reasons for their differences and speculates on the possible outcomes to Hu's subsequent career had their contentious relationship never existed.
High-dose vitamin supplements for cigarette smokers: caution is indicated

Results from human intervention studies indicate that smokers should avoid using high-dose dietary beta-carotene supplements. In addition, problems may exist for smokers with high-dose vitamin E supplements.
Prolonging β-lactam infusion: A review of the rationale and evidence, and guidance for implementation

Given the sparse antibiotic pipeline and the increasing prevalence of resistant organisms, efforts should be made to optimise the pharmacodynamic exposure of currently available agents. Prolonging the infusion duration is a strategy used to increase the percentage of the dosing interval that free drug concentrations remain above the minimum inhibitory concentration (fT>MIC), the pharmacodynamic efficacy driver for time-dependent antibiotics such as β-lactams. β-Lactams, the most commonly prescribed class of antibiotics owing to their efficacy and safety profile, have been the mainstay of therapy since the discovery of penicillin over 60 years ago. Mounting evidence, including the use of population pharmacokinetic modelling and Monte Carlo simulation, suggests that prolonging the infusion time of β-lactam antibiotics may have advantages over standard infusion techniques, including an enhanced probability of achieving requisite fT>MIC exposures, lower mortality and potentially reductions in infection/antibiotic-related costs. As a result of these favourable attributes, clinical practice guidelines support the use of prolonged-infusion β-lactams in the treatment of many severe infections. This article discusses the rationale and evidence for prolonging the infusion of β-lactam antibiotics and provides guidance for the implementation of a prolonged-infusion programme.
Determination of indium in rocks by substoichiometric radioisotope dilution analysis

Abstract Rocks containing 10–140 ng of indium per g are decomposed with hydrofluoric and nitric acids in the presence of 114 In. Indium is separated from other constituents by sequential extractions of the bromide, cupferronate, and acetylacetonate, and is then reacted with a substoichiometric amont of EDTA. Excess of indium is removed by acetylacetone extraction and the specific activity of the complexed fraction is determined by counting 114 In. Analyses of the U.S.G.S. standard rocks are reported. These show good agreement with previous neutron activation analyses. Repetitive rock analyses indicated an analytical precision of ±4–7%.
Active zones in CSG for accelerating boundary evaluation, redundancy elimination, interference detection, and shading algorithms

Solids defined by Boolean combinations of solid primitives may be represented in constructive solid geometry (CSG) as binary trees. Most CSG-based algorithms (e.g., for boundary evaluation, graphic shading, interference detection) do various forms of set-membership classification by traversing the tree associated with the solid. These algorithms usually generate intermediate results that do not contribute to the final result, and hence may be regarded as redundant and a source of inefficiency. To reduce such inefficiencies, we associate with each primitive A in a tree S an active zone Z that represents the region of space where changes to A affect the solid represented by S, and we use a representation of Z instead of S for set-membership classification. In the paper we develop a mathematical theory of active zones, prove that they correspond to the intersection of certain nodes of the original trees, and show how they lead to efficient new algorithms for boundary evaluation, for detecting and eliminating redundant nodes in CSG trees, for interference (null-set) detection, and for graphic shading.
Persistent properties of bifurcations

Abstract This paper reviews results about bifurcations which occur in families of differential equations. Persistent properties are defined to be those which remain when the family of equations is perturbed. We provide a list of such properties which is relevant for numerical studies of dynamical systems.
Direct Visualization of Lipid Phase Segregation in Single Lipid Bilayers with Coherent Anti-Stokes Raman Scattering Microscopy

Lipid rafts, segregated domains with different lipid compositions, are thought to play crucial roles in processes such as protein sorting and signaling on cell membranes. Despite their postulated importance in membrane biology, direct observation of lipid rafts in cells remains a challenge. To deepen the understanding of the chemical and physical characteristics of segregated lipid phase domains, model membrane systems have been extensively used. Supported monoand bilayers of binary mixtures of phospatidylcholines have segregated phase domains varying from tens of nanometers to several microns in size, which were revealed by atomic force microscopy and fluorescence microscopy. To eliminate the effects of geometrical constraints on domain formation, free-standing bilayers in the form of giant unilamellar vesicles (GUV) have been used as models for the cell membrane. Micrometer-sized domain structures have been seen in mixed bilayers of various phospholipids and in mixtures of phospholipids with sphingolipids. 10] Using the GUV model system, membrane phase diagrams have been obtained for ternary mixtures of saturated lipids, unsaturated lipids and cholesterol. The vesicle system has also proven suitable for membrane fluidity measurements and the determination of membrane tension and curvature at phase domain boundaries. Lipid phase separation in free-standing bilayers, however, has not been directly observed. Visualization of the different phases requires the addition of fluorescent compounds that have either a different affinity for the distinct lipid domains or a lipid environment-dependent fluorescence response. Variations in probe partitioning or photophysical changes not directly related to lipid phase domains can obscure a correct assignment of membrane morphology. In addition, it is generally assumed that interactions of the probes with the lipids are minor and not affecting the formation of segregated domains. Nevertheless, at concentrations up to a few mole percent, perturbing interactions cannot be completely ruled out. In a multicomponent system such as that of lipid membranes, small traces of charged or polar foreign molecules may distort the thermodynamics and kinetics of lipid phase segregation in bilayers. To rule out any artifacts, a clear visualization of lipid domains in free-standing bilayers without the addition of fluorescent labels is required for an unambiguous observation of phase-segregated lipid domains.
Fault identification in beam structures

Abstract A methodology based on the measurements of the natural frequencies of the structural system is developed for identification of the magnitude and location of the material defects and/or cracks. The numerical procedure is based on the matrix-transfer technique in which the dynamic characteristics of the system are related from one end to the other end via a transfer matrix. Numerical algorithms based on the multi-dimensional Newton-Raphson search technique are developed to enable systematic determination of the faults in the system. The defects in the structure are modeled as the overall change in material rigidity in a particular section. As demonstrated by the numerical experiments, the developed method can handle beams with variable cross-sections, as well as typical boundary conditions such as cantilever, simply supported and Winkler foundations. Both cases of single and multiple defects can be accurately predicted by the method.
Automatic determination of recommended test combinations for Ada compilers

Ada compilers are validated using the Ada Compiler Validation Capability (ACVC) test suite, containing over 4000 individual test programs. Each test program focuses, to the extent possible, on a single language feature. Despite the advantages of this “atomic testing” methodology, it is often the unexpected interactions between language features that result in compilation problems. This research investigated techniques to automatically identify recommended combinations of Ada languge features for compiler testing. A prototype program was developed to analyze the Ada language grammar specification and generate a list of recommended combinations of features to be tested. The output from this program will be used within the Ada Features Identification System (AFIS), a configuration management tool currently under development for the ACVC test suite. The prototype uses an annotated Ada language grammar to drive a test case generator. The generated combinations of Ada features are analyzed to select the combinations to be tested. While the skill and intuition of the compiler tester are eseential to the annotation of the Ada grammar, the prototype demonstrated that automated support tools can be used to identify recommended combinations for Ada compiler testing.
A comparison of mitochondrially synthesized proteins from whole mitochondria and cytochrome oxidase in Neurospora

The four mitochondrial proteins of Neurospora crassa labeled by amino acid incorporation in vivo in the presence of cycloheximide have been characterized with regard to their solubility properties in acidic chloroform-methanol. The labeled proteins are present in pulse-labeled whole mitochondria, pulse-chase labeled whole mitochondria, and a purified preparation of cytochrome oxidase. The labeled proteins in each of these preparations are similar with respect to molecular weight, as determined by dodecylsulfate · polyacrylamide-gel electrophoresis. In addition, proteins of similar molecular weight in each preparation exhibit identical solubility properties in acidic chloroform-methanol. The possibility of the mitochondrially synthesized subunits of cyto-chrome oxidase being representative of total mitochondrial protein synthesis is discussed.
Raman and IR spectra of crystalline phosphine in the γ phase

Abstract The γ phase of crystalline phosphine has been studied using IR and Raman spectroscopy. The observations include both pure phases, PH3 and PD3, and many of the modes of PH3, PH2D and PHD2 dilute in PD3 as well as of PD3, PD2H and PDH3 dilute in PH3. The phase transition β → γ is very slow for PH3, but much more rapid for PD3. Evidence is adduced pointing to the existence of inequivalent sites in this crystal, but none of a number of suggested models for the unit cell is entirely consistent with the numbers of multiplet components of the internal modes, nor with the numbers of external (lattice) modes observed in the IR and Raman.
Challenges in high-intensity laser injection into multiple optical fibers

A growing number of applications involve the transmission of high-intensity laser pulses through optical fibers. Previously, our particular interests led to a series of studies on single-fiber transmission of Q-switched, 1064 nm pulses from multimode Nd:YAG lasers through step-index, multimode, fused silica fibers. The maximum pulse energy that could be transmitted through a given fiber was limited by the onset of laser-induced breakdown or damage. Breakdown at the fiber entrance face was often the first limiting process encountered, but other mechanisms were observed that could result in catastrophic damage at either fiber face, within the initial "entry" segment of the fiber, and at other internal sites along the fiber path. These studies examined system elements that can govern the relative importance of different damage mechanisms, including laser characteristics, the design and alignment of laser-to-fiber injection optics, fiber end-face preparation, and fiber routing. In particular, criteria were established for injection optics in order to maximize margins between transmission requirements and thresholds for laser-induced damage. Recent interests have led us to examine laser injection into multiple fibers. Effective methods for generating multiple beams are available, but the resulting beam geometry can lead to challenges in applying the criteria for optimum injection optics. To illustrate these issues, we have examined a three-fiber injection system consisting of a beam-shaping element, a primary injection lens, and a grating beamsplitter. Damage threshold characteristics were established by testing fibers using the injection geometry imposed by this system design.
Biophysicochemical process coupling controls nitrogen use by benthic biofilms

A combination of macroscale and microscale observations was used to show that the interplay between hydrodynamic transport, local chemical conditions, and microbial metabolism controls nitrate use by benthic microbial communities. While it is usually assumed that interfacial transport and nutrient removal both increase monotonically with the velocity of the overlying flow, in laboratory flume experiments we observed substantially greater bulk nitrate removal under slower velocities (0.05 and 0.5 cm s21) than under a faster velocity (5 cm s21), with the greatest rate of nitrate removal occurring under the intermediate flow condition. These results demonstrate that hydrodynamic control of solute transport, specifically here the flux of oxygen and nitrate from the water column to the benthic microbial community, causes facultative bacteria to shift between anaerobic and aerobic metabolism under different flow conditions. Aerobic metabolism is promoted by more rapid hydrodynamic transport conditions, while anaerobic metabolism is favored under low-transport conditions. This type of coupling is expected to regulate microbial activity in all surficial sedimentary environments and must be parameterized in order to forecast long-term average biochemical transformation rates in rivers and other dynamic aquatic systems.
Consumer relationship proneness: a reexamination and extension across service exchanges

Purpose – This paper aims to answer two key questions focused on increasing the understanding of consumer relationship proneness (CRP) and its role in customer relationship management. First, is CRP linked to trust and other relationship outcomes (e.g. customer share, adherence)? Second, does the nature of the service exchange (transactional versus relational) affect the association between CRP and commitment and trust?Design/methodology/approach – Data were collected in three contexts: 270 travel industry call center customers, 345 insurance agency clients, and 897 patients responded to our surveys about their business relationships.Findings – Structural modeling analysis and t‐statistic comparisons revealed that CRP is associated with trust and other important outcomes (i.e. share of customer and adherence) and that the nature of the service exchange moderates the association between CRP and commitment and trust. Specifically, as the nature of the service exchange moves from transactional to relational,...
Endomyocardial biopsy detection of acute rejection in cardiac allograft recipients.

Endomyocardial biopsy provides a safe, reliable, morphologic index of acute rejection and has an important role to play in the management of patients in whom acute rejection occurs. Repeated endomyocardial biopsies are well tolerated, permitting monitoring of acute rejection in cardiac recipients. Some patients have undergone over 30 serial biopsies. Adequate sampling requires at least four pieces of tissue. The biopsies are graded in the following manner: (a) Mild acute rejection is characterized by a perivascular and mild interstitial infiltrate of pyroninophilic lymphoblasts wihtout myocyte necrosis. (b) Moderate acute rejection has an increased infiltrate extending into the interstitium and causing focal myocyte necrosis. This requires augmentation of immunosuppression. (c) Severe acute rejection, which is more difficult to reverse, includes a more prolific infiltrate with the addition of neutrophils, hemorrhage, and increased myocyte necrosis. (d) Ongoing acute rejection implies that the degree of acute rejection is the same, or worse, than the previous biopsy. (e) Resolving or resolved acute rejection shows reparative changes with diminishing or absent inflammatory infiltrate following treatment. Recipients treated with Cyclosporin-A develop rejection and respond to treatment more slowly than with conventional treatment. This group also develops endocardial infiltrates and a dose-related fine perimyocytic cardiac fibrosis. The endomyocardial biopsy is also useful in identifying infectious agents, for example, toxoplasmosis in cardiac recipients.
Role of Kinins in the Renal Response to Enalaprilat in Normotensive and Hypertensive Rats

Abstract This study examined the role of endogenous kinins in the alteration of renal hemodynamics induced by low-dose converting enzyme inhibition in hydropenic normotensive rats and in the nonclipped kidney of hydropenic two-kidney, one clip hypertensive rats. Infusion of a bradykinin B 2 receptor antagonist (d-Arg 0 ,[Hyp 3 ,Thi 5,8 ,d-Phe 7 ]-bradykinin, 1 or 10 μg · kg −1 · min −1 ) did not alter renal function of normotensive rats. In a second series of experiments, infusion of enalaprilat at 0.1 mg · kg −1 · h −1 increased renal blood flow ( P P −1 · min −1 during the enalaprilat infusion decreased renal blood flow to a value similar to the preenalaprilat baseline and significantly different from the mean of the two enalaprilat periods before and after the addition of the kinin antagonist—the “mean effect of enalaprilat.” The decrease in renal blood flow induced by the kinin antagonist was associated with an increase in renal vascular resistance above the mean effect of enalaprilat ( P
Microfabricated isoelectric focusing device for direct electrospray ionization-mass spectrometry.

A novel microfabricated device for isoelectric focusing (IEF) incorporating an optimized electrospray ionization (ESI) tip was constructed on polycarbonate plates using laser micromachining. The IEF microchip incorporated a separation channel (50 μ × 30 μ × 16 cm), three fluid connectors, and two buffer reservoirs. Electrical potentials used for IEF focusing and electrospray were applied through platinum electrodes placed in the buffer reservoirs, which were isolated from the separation channel by porous membranes. Direct ESI-mass spectrometry (MS) using electrosprays produced directly from a sharp emitter „tip” on the microchip was evaluated. The results indicated that this design can produce a stable electrospray and that performance was further improved and made more flexible with the assistance of a sheath gas and sheath liquid. Error analysis of the spectral data showed that the standard deviation in signal intensity for an analyte peak was less than ˜ 5% over 3 h. The production of stable electrosprays directly from microchip IEF device represents a step towards easily fabricated microanalytical devices. Microchannel IEF separations of protein mixtures were demonstrated for uncoated polycarbonate microchips. Direct microchannel IEF-ESI-MS was demonstrated using the microfabricated chip with an ion-trap mass spectrometer for characterization of protein mixtures.
Imaging of Single Extended DNA Molecules on Flat (Aminopropyl)triethoxysilane−Mica by Atomic Force Microscopy

Long strands of DNA have been deposited, extended, and immobilized on chemically modified mica for study with an atomic force microscope (AFM). By employing a modified `molecular combing` technique and carefully silanized mica, we show that DNA molecules may be distributed uniformly, adsorbed in extended conformations, and bound with great tenacity. When maintained in a buffer solution, these strands remained stable for >5 h. Scanning the surface with high loads applied to an AFM tip induced fragmentation in the strands, but remaining pieces never relinquished their original positions. Further imaging applications, such as after treatment of the DNA by molecular hybridization or DNA synthesis and labeling in situ, are discussed. 15 refs., 4 figs.
PMP22 expression in dermal nerve myelin from patients with CMT1A

Charcot-Marie-Tooth disease type 1A (CMT1A) is caused by a 1.4 Mb duplication on chromosome 17p11.2, which contains the peripheral myelin protein-22 (PMP22) gene. Increased levels of PMP22 in compact myelin of peripheral nerves have been demonstrated and presumed to cause the phenotype of CMT1A. The objective of the present study was to determine whether an extra copy of the PMP22 gene in CMT1A disrupts the normally coordinated expression of PMP22 protein in peripheral nerve myelin and to evaluate PMP22 over-expression in patients with CMT1A and determine whether levels of PMP22 are molecular markers of disease severity. PMP22 expression was measured by taking skin biopsies from patients with CMT1A (n = 20) and both healthy controls (n = 7) and patients with Hereditary Neuropathy with liability to Pressure Palsies (HNPP) (n = 6), in which patients have only a single copy of PMP22. Immunological electron microscopy was performed on the skin biopsies to quantify PMP22 expression in compact myelin. Similar biopsies were analysed by real time PCR to measure PMP22 mRNA levels. Results were also correlated with impairment in CMT1A, as measured by the validated CMT Neuropathy Score. Most, but not all patients with CMT1A, had elevated PMP22 levels in myelin compared with the controls. The levels of PMP22 in CMT1A were highly variable, but not in HNPP or the controls. However, there was no correlation between neurological disabilities and the level of over-expression of PMP22 protein or mRNA in patients with CMT1A. The extra copy of PMP22 in CMT1A results in disruption of the tightly regulated expression of PMP22. Thus, variability of PMP22 levels, rather than absolute level of PMP22, may play an important role in the pathogenesis of CMT1A.
Effect of interferon on exogenous, endogenous, and chronic murine leukemia virus infection

Abstract The effect of purified mouse interferon on the replication of AKR mouse leukemia virus (MLV) in a clonal line of AKR cells was studied, with emphasis on comparing the effect of interferon on the replication of exogenous virus, activation of endogenous virus by IdUrd, and production of virus by chronically infected cells. It was found that interferon inhibited replication of virus in all three systems. Interferon did not abort exogenous infection or virus induction by IdUrd, but only delayed appearance of infectious virus. Virus production by chronically infected cells also was suppressed in the presence of interferon; however, after removal of interferon, rapid recovery of virus production occurred. Under conditions where interferon treatment inhibited virus yield as measured both by infectious virus and virion-associated reverse transcriptase activity, no significant inhibition of synthesis of virus specific (gs) antigen was observed (as measured by immunofluorescence and radioimmunoassay for p30 protein). These results indicate that unlike its effect on the majority of viruses, interferon does not inhibit MLV by a general inhibition of viral protein synthesis; rather, it appears to inhibit one or more of the later steps in MLV replication which occur after the expression of viral gs antigen. The interferon block of acute exogenous or IdUrd-induced endogenous infection appeared to occur prior to virus assembly, resulting in a marked decrease in the number of free and cell-associated particles. In the chronic infection, however, the interferon treatment only partially prevented assembly and release of virus particles, but these had markedly reduced infectivity.
Dimensional stability of record bases fabricated from light-polymerized composite using two methods

Abstract Statement of problem. Record bases fabricated from resin-based composite, which undergoes polymerization shrinkage during curing, can distort during curing to produce significant gaps along the posterior border. Purpose. This study evaluated the pattern of gap formation that occurs over the palatal area of a maxillary record base fabricated from light-cured composite (Triad), and determined whether changes in the fabrication method affects the size and pattern of gap formation. Effects of composite width and passage of time on gap formation were also analyzed. Material and methods. Twenty record bases were fabricated with two methods: (1) according to the manufacturer's directions, the entire surface of the record base was exposed to the curing light; and (2) the palatal area of the record base was covered with foil to prevent light penetration, and the base was light cured in three stages with readaptation of the uncured composite between stages. Ten record bases from each group were tested 1 hour after fabrication; the remaining 10 from each group were tested 7 days after fabrication. Measurements of adaptation were made at three points representing the right and left ridge crests and midpalatal areas. The first measurement was taken at the posterior border and subsequent measurements were made at 5 mm increments after reduction of the posterior border of the cast and record base with a model trimmer. Results. Dimensional changes were observed in both procedures. The largest discrepancy occurred at the posterior border of record bases fabricated using method 1. Mean gap formation at the posterior border in this group after 1 hour was 454, 729, and 334 μm and 483, 841, and 330 μm after 7 days at points A, B, and C, respectively. Record bases fabricated with procedure 2 demonstrated mean gap sizes at the posterior border after 1 hour of 219, 421, and 208 μm and 267, 403, and 192 μm after 7 days at points A, B, and C, respectively. No significant influence of composite width on gap size was found. Conclusion. The average gap size due to stage curing (method 2) was never greater than the corresponding gap that arose from the use of the manufacturer's recommendations (method 1). Limiting the amount of surface area exposed to the curing light and readapting the uncured composite to the cast between curing episodes can significantly reduce the mean gap size occurring at the posterior border. (J Prosthet Dent 1998;79:399-403.)
Calcium and flagellar response during the chemotaxis of bracken spermatozoids.

The attraction of fern spermatozoids by secretions from the female reproductive structures, and by salts of malic acid, has long been known as a classic example of precise chemotactic orientation by motile cells. Spermatozoids of the bracken fern are attracted by the partially ionized form of malic acid, bimalate ion, and also by calcium ions. Both calcium and bimalate ions must be present for chemotactic response and for response to voltage gradients, Spermatozoids swimming up a bimalate concentration gradient swim in helical paths of abnormally small radius; if they accidentally swim down the concentration gradient the radii of their path helices become abnormally large. These observations suggest that changes in the direction of flagellar beating in response to the rate of change of bimalate ion concentration with time may be the basis for chemotactic orientation. A “coupled diffusion” hypothesis for chemo-reception is presented, which postulates a membrane carrier which can only circulate freely in the membrane if it binds both bimalate and calcium ions. This hypothesis could explain time-differentiation of the stimulus, the coupling of a specific stimulus — bimalate ions — to a general mediator of intracellular response — calcium ions — and the quantitative relationship between response of the spermatozoids and the chemical potential of “calcium bimalate.”
Universities marginalize online courses

Why should faculty members develop online courses if the effort may be detrimental to their promotion or tenure?
Stokes Flow in a Driven Sector by Two Different Methods

A biorthogonal series expansion and a numerical finite-difference approximation are applied to the problem of steady Stokes flow in a driven sector of 10° total angle, providing mutual support of the theoretical techniques. For this problem the method of biorthogonal series is faster, cheaper, and more accurate.
Life histories of pathogen populations.

Summary The populations of pathogens in individual hosts have many of the characteristics of multicellular organisms, or individuals. These populations go through a life cycle within a host and they reproduce by founding daughter populations in new hosts. Natural selection shapes the life history characteristics of pathogen populations–life expectancy, trade-offs in the allocation of resources between growth, survival, and fecundity, and aging–in ways that maximize the reproductive fitness of the pathogens. In turn, these life history characteristics shape the natural histories of infectious diseases. Transmissibility and virulence may be thought of as properties of pathogen populations rather than as properties of the constituent microorganisms within these populations. The poor correlation of virulence with pathogen fitness is a major obstacle to the development of a theory of virulence. Consideration of the life histories of pathogen populations complements the traditional epidemiological focus on host populations and provides a valuable perspective for understanding human infectious diseases.
Ventricular fibrillation associated with two functioning implanted cardiac pacemakers

Abstract We have reported a case of two functioning cardiac pacemakers associated with repeated bouts of ventricular fibrillation. It would appear from the electrocardiograms and subsequent clinical course that the arrhythmia was induced by the interaction of the cardiac pacemakers. Possible mechanisms for the association of serious ventricular arrhythmias with the separate functioning of the pacemakers are discussed.
Efficiency Analysis: A Primer on Recent Advances

This monograph reviews the econometric literature on the estimation of stochastic frontiers and technical efficiency. Special attention is devoted to current research.
Using metaphors to create a natural user interface for microsoft surface

Creating a new model of human computer interaction is not straightforward. Only a handful of such models have been commercially successful. Those that have, such as the graphical user interface (GUI), can provide valuable lessons. When we were challenged to develop a new natural user interface design for Microsoft Surface, we drew from these lessons and from modern user research techniques. A prominent starting point resulting from this was using metaphors to develop the new user interface. We used metaphors for two reasons: To create a user interface world that was understandable and predictable for our users, and to guide the design team in creating the detailed user interface design. We continued this practice in the user research: We focused on which metaphors worked best in the studies, and learned if users understood the metaphors we were using and which metaphor they preferred. This case study describes the process we followed, and the lessons we learned from this.
New multi-purpose chemitrodes for electrical and chemical stimulation or localized perfusion of the brain

The design and construction of two sizes of bipolar chemitrodes are described for stimulating directly a single site in the brain of a rat, cat, monkey or other animal. These chemitrodes are used for the injection of a drug at the same time that electrical stimulation is applied, or for the localized push-pull perfusion of the same locus. They also permit the recording of electrical potentials at the tip of the guide tube. The chemitrodes may be implanted chronically for the purpose of examining the relationship between chemically and electrically elicited responses in the awake and unrestrained animal.
On predicting Twitter trend: factors and models

In this paper, we predict hashtag trend in Twitter network with two basic issues under investigation, i.e. trend factors and prediction models. To address the first issue, we consider different content and context factors by designing features from tweet messages, network topology, user behavior, etc. To address the second issue, we adopt prediction models that have different combinations of the two basic model properties, i.e. linearity and state-space. Experiments on large Twitter dataset show that both content and context factors can help trend prediction. However, the most relevant factors are derived from user behaviors on the specific trend. Non-linear models are significantly better than their linear counterparts, which can be further slightly improved by the adoption of state-space models.
Timing Preservation in Wire Spreading Utilized for Yield Improvement

Today's submicron technologies increase the IC sensitivity to the physical manufacturing defects, which results in poor initial product yield. It is well known that IC layout can be made more robust to the defects by making changes to the layout such as: adding extra vias in place of single vias (redundant via insertion), thickening thin wires (wire widening) and moving wires so that they are further apart (wire spreading). Today all these techniques are not timing aware and therefore can create additional timing violations. Wire spreading with no timing information in our experiments could create up to 490ps timing degradation. Even if the overall yield is improved, with such timing degradation, the design is not acceptable for manufacturing. This paper presents simple yet very effective timing preservation technique for wire spreading yield improvement at the post processing stage. Our results show that it is possible to control the timing during wire spreading - setup/hold slack stays the same or improved comparing to the initial slack
Hyperfine splitting of P states in heavy quarkonia

The splitting between the $^{1}\mathrm{P}_{1}$ and the center of gravity of the $^{3}\mathrm{P}_{\mathrm{j}}$ states of heavy quarkonia is evaluated using the perturbative QCD expression for the hyperfine potential. The theoretical result is about 1% of the absolute fine-structure splitting and disagrees with an experimental value.
Evaluating remedial alternatives for an acid mine drainage stream: application of a reactive transport model.

A reactive transport model based on one-dimensional transport and equilibrium chemistry is applied to synoptic data from an acid mine drainage stream. Model inputs include streamflow estimates based on tracer dilution, inflow chemistry based on synoptic sampling, and equilibrium constants describing acid/base, complexation, precipitation/ dissolution, and sorption reactions. The dominant features of observed spatial profiles in pH and metal concentration are reproduced along the 3.5-km study reach by simulating the precipitation of Fe(III) and Al solid phases and the sorption of Cu, As, and Pb onto freshly precipitated iron(III) oxides. Given this quantitative description of existing conditions, additional simulations are conducted to estimate the streamwater quality that could result from two hypothetical remediation plans. Both remediation plans involve the addition of CaCO3 to raise the pH of a small, acidic inflow from 2.4 to 7.0. This pH increase results in a reduced metal load that is routed downstream by the reactive transport model, thereby providing an estimate of postremediation water quality. The first remediation plan assumes a closed system wherein inflow Fe(II) is not oxidized by the treatment system; under the second remediation plan, an open system is assumed, and Fe(II) is oxidized within the treatment system. Both plans increase instream pH and substantially reduce total and dissolved concentrations of Al, As, Cu, and Fe(II+III) at the terminus of the study reach. Dissolved Pb concentrations are reduced by 18% under the first remediation plan due to sorption onto iron(III) oxides within the treatment system and stream channel. In contrast, iron(III) oxides are limiting under the second remediation plan, and removal of dissolved Pb occurs primarily within the treatment system. This limitation results in an increase in dissolved Pb concentrations over existing conditions as additional downstream sources of Pb are not attenuated by sorption.
A qualitative and quantitative analysis of the human fovea during development

The anatomical development of the human fovea has been sampled from 22 weeks gestation to adulthood, using both qualitative and quantitative methods. The foveal depression continues to deepen after birth until 15 months, due to the migration of the cells of the inner retina toward the periphery. Before birth the rod-free zone or foveola is over 1000 microns in diameter, but it becomes progressively narrower after birth because of a centralward migration of cones. It reaches the adult diameter of 650-700 microns by 45 months of age. Postnatally, foveolar cone development is characterized by maturation, elongation, and an increase in packing density. Foveolar cone diameter changes markedly after birth, going from 7.5 microns at 5 days postnatal to 2 microns by 45 months. During this time the foveolar cone develops both its outer segment and basal axon process (fiber of Henle). This combination of elongation and centralward migration results in an increase of foveolar cone density from 18 cones/100 microns at 1 week postnatal to 42 cones/100 microns in the adult. Measures of foveola width and cone diameter reach the adult stage of development at 45 months of age, but the two important visual factors of outer segment length and cone packing density still are only half the adult values at 45 months of age.
Vagal stimulation induces expiratory lengthening in the in vitro neonate rat

Respiration is modulated by lung mechanoreceptor feedback in vivo on a cycle-to-cycle basis. We replicated this modulation in vitro and tested four stimulus protocols to identify which of these most closely replicated in vivo responses to lung mechanoreceptor activation in mammals. We activated pulmonary vagal afferent pathways by electrical stimulation or by lung inflation, applied during expiration, which produces expiratory lengthening in vivo. In each modality, transient and tonic stimuli were applied. Stimuli were applied over a range of delays following inspiratory termination. Tonic stimuli were maintained until subsequent inspiratory onset. All stimulus modalities prolonged expiration (P < 0.05). These results indicate that the neural circuitry mediating pulmonary afferent modulation of expiratory duration is retained in vitro.
Young Children's Ability to Detect Ambiguity in Descriptions of Location.

Abstract Three experiments investigated 3- to 5-year-olds' ability to detect ambiguity in descriptions of location. In Experiments 1 and 2, children received ambiguous (e.g., “it's in one of the bags”) and nonambiguous (e.g., “it's in the bag by the chair”) descriptions. Four- and 5-year-olds' search latencies were longer for ambiguous than for nonambiguous descriptions, but 3-year-olds' latencies were longer for nonambiguous than for ambiguous descriptions. Experiment 3 revealed no difference in 3-year-olds' search latencies for ambiguous and nonambiguous descriptions when amount of spatial information in directions was equated. Five-year-olds' latencies again were longer for ambiguous than for nonambiguous descriptions. Discussion focuses on possible developmental factors contributing to changes in children's ability to detect spatial ambiguity.
NPN fuzzy sets and NPN qualitative algebra: a computational framework for bipolar cognitive modeling and multiagent decision analysis

An NPN (Negative-Positive-Neutral) fuzzy set theory and an NPN qualitative algebra (Q-algebra) are proposed which form a computational framework for bipolar cognitive modeling and multiagent decision analysis. First a 6-valued NPN logic is introduced which extends the usual 4-valued Q-algebra (S,/spl ap/,/spl oplus/,/spl otimes/) and S={+,-,0,?} by adding one more level of specification; and then a real-valued NPN fuzzy logic is introduced which extends the 6-valued model to the real space {/spl forall/(x,y)|(x,y)/spl isin/[-1,0]/spl times/[0,1]} and adds infinite levels of specifications, As a generalization, a fuzzy set theory is presented that allows /spl beta/-level fuzzy number-based NPN variables (x,y) to be substituted into (S,/spl ap/,/spl oplus/,/spl otimes/) where /spl otimes/ stands for any NPN T-norm; /spl oplus/ stands for disjunction (V) or union (/spl cup/), and /spl beta/ is the number of /spl alpha/-cuts.
Fishing for Function in Zebrafish

See related article, pages 846–855 Zebrafish have emerged as a powerful and inexpensive vertebrate model system to study the regulation and function of genes. Though this model has been under investigation for more than half a century,1 97% of the published work relating to zebrafish has accumulated in only the last 15 years (Figure). Two important developments have facilitated the rapid ascent of zebrafish as a model system, particular for vascular biology. First, forward genetic screens in zebrafish identified a number of fascinating vascular phenotypes such as gridlock (aortic coarctation) and cloche (loss of endothelial cells [ECs]).2,3 Second, microangiography, coupled to transgenic lines of fish carrying an endothelial cell promoter–driven reporter (eg, green fluorescent protein, GFP), has allowed for the mapping of the zebrafish vasculature in stunning detail with never-before-seen vascular processes amenable to real time visualization.4 These technologies, and evolving tools in reverse genetics, have led to the identification of numerous genes linked to vascular pathology, some of which phenocopy diseases seen in humans (Table). As the Table indicates, essentially all of the zebrafish vascular phenotypes involve perturbations in endothelial cell differentiation, migration, and vascular tube formation with little insight into the role of supportive smooth muscle cells (SMCs). Difficulty in assessing vascular SMC biology in zebrafish stems from our incomplete understanding of the timing of SMC recruitment to the vessel wall, the extent of SMC investment, and the notable lack of SMC markers. Thus, to realize the full potential of zebrafish as a model for vascular biology, developments in these areas of research are necessary, particularly given the importance of SMC in mammalian vascular pathobiology. Exponential rise in zebrafish publications. Data obtained from a PubMed Central search on 4 March 2006 using the keywords zebrafish and brachydanio (its older designation). The numbers above each …
Exercise-Induced Silent Myocardial Ischemia in Master Athletes

High-physical activity levels are associated with reduced risk of symptomatic coronary artery disease (CAD). However, there are a number of reports of exercise-related sudden death and myocardial infarction in aerobically trained athletes. This study compared the prevalence of exercise-induced silent myocardial ischemia on maximum graded exercise tests with tomographic thallium scintigraphy in 70 master male athletes (63 +/- 6 years, mean +/- SD) (maximum aerobic capacity, VO2max >40 ml/kg/min) and in 85 healthy untrained men (61 +/- 7 years) with no history of CAD. The prevalence of silent ischemia (exercise-induced ST-segment depression on electrocardiogram and perfusion abnormalities on thallium scintigraphy) was similar in athletes and untrained men; 16% of the athletes (11 of 70) had silent ischemia compared with 21% of the untrained men (chi-square = 0.81, p = 0.36). No athletes had hyperlipidemia, systemic hypertension, or diabetes mellitus. However, the apolipoprotein E4 allele was present in 9 of the 11 athletes with silent ischemia compared with 2 of 32 athletes with normal exercise tests (chi-square = 24, p = 0.0001). These results suggest that older male athletes with the apolipoprotein E4 allele are at increased risk for the development of exercise-induced silent ischemia.