cssi/SciSciGPT-SciSciNet huggingface dataset:
Organization and Expression of tRNA Genes in Drosophila Melanogaster

Transfer RNA molecules are an integral component of the cellular protein-synthesizing machinery responsible for matching a codon in an RNA with the appropriate anticodon so that the correct amino acid is inserted into the growing polypeptide chain. In addition, tRNA species have also been implicated in various regulatory processes (for review, see LaRossa and Soll 1978). All tRNAs possess similar general structural features which allow for efficient recognition by the ribosome or by some nucleases involved in tRNA maturation. They also contain specific recognition features for interaction with cognate aminoacyl-tRNA synthetases and tRNA modifying enzymes. Thus tRNA, with its relatively small size but diverse structural and functional characteristics, provides a potentially useful molecule for the study of macromolecular structure-function relationships.
The functional role of a noninactivating sodium current in neocortical neurons

Neocortical neurons have a tetrodotoxin (TTX) sensitive noninactivating current. Whole cell voltage clamp shows this current is activated about 10 mV negative to spike threshold. On-cell patches show transient sodium channels that fail to activate in less than 1% of the depolarizations which is compatible with the magnitude of the persistent cuurrent. This rare modal change in inactivation provides the cell with a small persistent current mechanism that amplifies depolarizing synaptic currents. Its presence in dendrites effectively shortens the electrical length of the dendrites.
Limiting feeding to the active phase reduces blood pressure without the necessity of caloric reduction or fat mass loss.

Reducing body weight has been shown to lower blood pressure in obesity-related hypertension. However, success of those lifestyle interventions is limited due to poor long-term compliance. Emerging ...
Methicillin-resistant Staphylococcus aureus Colonization and Pre- and Post-hospital Discharge Infection Risk.

Background The Department of Veterans Affairs implemented an active surveillance program for methicillin-resistant Staphylococcus aureus (MRSA) in 2007 in which acute care inpatients are tested for MRSA carriage on admission, unit-to-unit transfer, and discharge. Using these data, we followed patients longitudinally to estimate the difference in infection rates for those who were not colonized, those who were colonized on admission (importers), and those who acquired MRSA during their stay. We examined MRSA infections that occurred prior to discharge and at 30, 90, 180, and 365 days after discharge. Methods We constructed a dataset of 985626 first admissions from January 2008 through December 2015 who had surveillance tests performed for MRSA carriage. We performed multivariable Cox proportional hazards and logistic regression models to examine the relationship between MRSA colonization status and infection. Results The MRSA infection rate across the predischarge and 180-day postdischarge time period was 5.5% in importers and 7.0% in acquirers without a direct admission to the intensive care unit (ICU) and 11.4% in importers and 11.7% in acquirers who were admitted directly to the ICU. The predischarge hazard ratio for MRSA infection was 29.6 (95% confidence interval [CI], 26.5-32.9) for importers and 28.8 (95% CI, 23.5-35.3) for acquirers compared to those not colonized. Fully 63.9% of all MRSA pre- and postdischarge infections among importers and 61.2% among acquirers occurred within 180 days after discharge. Conclusions MRSA colonization significantly increases the risk of subsequent MRSA infection. In addition, a substantial proportion of MRSA infections occur after discharge from the hospital.
Living on a prayer: neo-monasticism and socio-ecological change

Neo-monasticism, including the desire to live in Christian intentional community, is increasingly popular in the United States. Communities are structured around a rule or shared covenant that outl...
Ethanol acts on KCNK13 potassium channels in the ventral tegmental area to increase firing rate and modulate binge–like drinking

Abstract Alcohol excitation of the ventral tegmental area (VTA) is important in neurobiological processes related to the development of alcoholism. The ionotropic receptors on VTA neurons that mediate ethanol-induced excitation have not been identified. Quinidine blocks ethanol excitation of VTA neurons, and blockade of two-pore potassium channels is among the actions of quinidine. Therefore two-pore potassium channels in the VTA may be potential targets for the action of ethanol. Here, we explored whether ethanol activation of VTA neurons is mediated by the two-pore potassium channel KCNK13. Extracellular recordings of the response of VTA neurons to ethanol were performed in combination with knockdown of Kcnk13 using a short hairpin RNA (shRNA) in C57BL/6 J mice. Real-time PCR and immunohistochemistry were used to examine expression of this channel in the VTA. Finally, the role of KCNK13 in binge-like drinking was examined in the drinking in the dark test after knockdown of the channel. Kcnk13 expression in the VTA was increased by acute ethanol exposure. Ethanol-induced excitation of VTA neurons was selectively reduced by shRNA targeting Kcnk13. Importantly, knockdown of Kcnk13 in the VTA resulted in increased alcohol drinking. These results are consistent with the idea that ethanol stimulates VTA neurons at least in part by inhibiting KCNK13, a specific two-pore potassium channel, and that KCNK13 can control both VTA neuronal activity and binge drinking. KCNK13 is a novel alcohol-sensitive molecular target and may be amenable to the development of pharmacotherapies for alcoholism treatment.
Outcomes and Resource Utilization in Robotic Mitral Valve Repair: Beyond the Learning Curve

BACKGROUND After the initial learning curve associated with mastering a robotic procedure, there is a plateau where operative time and complication rates stabilize. Our objective was to evaluate one surgeon's experience with robotic mitral valve repairs (MVRep) beyond the learning curve and to compare its effectiveness against the traditional open approach. METHODS Data from Ronald Reagan University of California, Los Angeles Medical Center was prospectively collected from January 2008 to March 2016 to identify adult patients undergoing robotic MVRep. Operative times, complication rates, and cost for robotic versus open MVRep were compared using multivariate regressions, adjusting for comorbidities and previous cardiac surgeries. RESULTS During the study period, 175 robotic (41%) and 259 open (59%) MVRep cases were performed at our institution. As the surgeon performed more robotic operations, there was a decrease in room time (554-410 min, P < 0.001), surgery time (405-271 min, P < 0.001), and cross-clamp times (179-93 min, P < 0.001). After application of a multivariate regression model, robotic MVRep was associated with lower odds of complications (odds ratio = 0.42, P = 0.001), shorter length of stay (β = -2.51, P < 0.001), and a reduction of 11% in direct (P = 0.003) and 24% in room costs (P < 0.001), but a 51% increase in surgery cost (P < 0.001). CONCLUSIONS As the surgeon gained experience with robotic MVRep, operative times decreased in a steady manner. Robotic MVRep had comparable outcomes to open MVRep and lower overall cost. The observed difference in costs is likely related to shorter length of stay and lower room cost with the robotic approach.
Measuring voltage and ion concentrations in live embryos.

Abstract Homeostasis of charged particles in biological systems is fundamental for life. Indeed, the efficient synthesis of ATP is predicated on an electrochemical gradient. Ion pumps and channels act as conduits that regulate membrane potential by controlling ion flux. This phenomenon is critical for the generation of action potentials in excitable cells such as neurons and muscle fibers, and for acidification of lysosomes in all cells. However, the production of action potentials or pH differentials is merely one facet of bioelectricity. Increasing evidence has shown that ion channels and pumps also play critical roles in other cellular processes: cell cycle regulation, wound healing, regeneration, and symmetry breaking during development. In recent years, the functional roles of ion channels have been explored in echinoderm development. The application of fluorescence-based ion- and voltage-sensitive dyes allows for live measurements of ion concentrations with both spatial and temporal resolution. In this chapter, we describe the use of such dyes for interrogating and visualizing ion and voltage gradients in sea urchin embryos.
Microvascular bioengineering: a focus on pericytes

Capillaries within the microcirculation are essential for oxygen delivery and nutrient/waste exchange, among other critical functions. Microvascular bioengineering approaches have sought to recapitulate many key features of these capillary networks, with an increasing appreciation for the necessity of incorporating vascular pericytes. Here, we briefly review established and more recent insights into important aspects of pericyte identification and function within the microvasculature. We then consider the importance of including vascular pericytes in various bioengineered microvessel platforms including 3D culturing and microfluidic systems. We also discuss how vascular pericytes are a vital component in the construction of computational models that simulate microcirculation phenomena including angiogenesis, microvascular biomechanics, and kinetics of exchange across the vessel wall. In reviewing these topics, we highlight the notion that incorporating pericytes into microvascular bioengineering applications will increase their utility and accelerate the translation of basic discoveries to clinical solutions for vascular-related pathologies.
Reducing Stress and Enhancing the General Well-Being of Teachers Using T’ai Chi Chih® Movements: A Pilot Study

The purpose of this study was to examine the effects of T’ai Chi Chih® (TCC) discipline on the physical symptoms of stress and the general well-being of 35 teachers. Teachers completed 15 hours of instruction and practice in a two-day format with four additional weeks of practice. The 23 teachers who completed pre-posttests showed significant improvement of their general well-being and reduction in perceived stress symptoms. Qualitative data from the teachers supported these results. Within the limitations of the study design it was concluded that this relatively new, easy to learn method of T’ai Chi has potential to enhance well-being and reduce stress symptoms of teachers. Teachers and other educational professionals may want to learn more about T’ai Chi Chih® discipline for its stress reducing benefits and enhancement of general well-being.
Contemporary prevalence, trends, and outcomes of coronary chronic total occlusions in acute myocardial infarction with cardiogenic shock

Abstract Background There are limited data on the prevalence and outcomes of chronic total occlusions (CTO) of the coronary artery in acute myocardial infarction with cardiogenic shock (AMI-CS) patients. Methods Using the National Inpatient Sample, all admissions with AMI-CS that underwent diagnostic angiography between January 1, 2008, and December 31, 2014, were included. CTO, percutaneous coronary intervention (PCI), comorbidities and concomitant cardiac arrest was identified for all admissions. Outcomes of interest included temporal trends, in-hospital mortality, and resource utilization in cohorts with and without CTO. Results In this 7-year period, 163,628 admissions with AMI-CS admissions met the inclusion criteria, with 68% being ST-elevation AMI-CS. CTO was noted in 27,343 (16.7%) admissions, with an increase in prevalence during the study period. The cohort with CTOs was more likely to be male and bearing private insurance. The CTO cohort had higher cardiovascular comorbidity, higher rates of cardiac arrest and higher use of PCI and mechanical circulatory support. The presence of a CTO was independently associated with higher in-hospital mortality (adjusted odds ratio 1.20 [95% confidence interval 1.16–1.23]; p Conclusions In this cohort of AMI-CS admissions that underwent diagnostic angiography, the presence of a CTO identified a higher risk cohort that had higher in-hospital mortality.
Should Multifocality be an Indication for Completion Thyroidectomy in Papillary Thyroid Carcinoma

Abstract Background Multifocality in papillary thyroid carcinoma is common. The aim of this study is to determine whether patients with multifocal disease, treated with lobectomy alone, have an increased risk of contralateral lobe papillary thyroid carcinoma, regional recurrence, and poorer survival. Methods After institutional review board approval, papillary thyroid carcinoma patients managed from 1986 to 2015 with lobectomy alone were identified from an institutional database. Papillary thyroid carcinoma patients with pT3 to T4 classification, nodal disease, or distant metastases were excluded. After excluding 40 patients who underwent an immediate completion thyroidectomy, 849 were included in the analysis; 619 (72.9%) had unifocal disease and 230 (27.1%) had multifocal disease. Contralateral lobe papillary thyroid carcinoma-free probability, regional recurrence-free probability, disease-specific survival, and overall survival were calculated using the Kaplan-Meier method. Results With a median follow-up of 58 months, unifocal disease and multifocal disease patients had similar rates of contralateral lobe papillary thyroid carcinoma, regional recurrence, and overall survival (10-year contralateral lobe papillary thyroid carcinoma-free probability 98.6% vs 97.8%; regional recurrence-free probability 99.5% vs 99.4%; overall survival 91.6% vs 93.1%, respectively). There were no disease-related deaths. Conclusion Select multifocal disease patients, managed with lobectomy alone, have rates of contralateral lobe papillary thyroid carcinoma, regional recurrence, and overall survival comparable to unifocal disease patients. Multifocal disease should not be an indication for completion thyroidectomy.
Automatically identifying valid API versions for software development tutorials on the Web

Abstract Online tutorials are a valuable source of community‐created information used by numerous developers to learn new APIs and techniques. Once written, tutorials are rarely actively curated an...
Authorized Agent–Controlled Analgesia for Pain Management in Critically Ill Adult Patients

BACKGROUND Patient-controlled analgesia is commonly used for adult patients requiring parenteral opioid analgesia in the postoperative setting. However, many patients are unable to use patient-controlled analgesia because of physical or cognitive limitations. Authorized agent-controlled analgesia, in which a nurse or family member activates the patient-controlled analgesia device, has been studied in the pediatric population but has received little attention in adults. OBJECTIVE To evaluate the efficacy of authorized agent-controlled analgesia in critically ill adult patients. METHODS A retrospective pilot study was conducted involving 46 patients who were placed on an authorized agent-controlled analgesia protocol in a mixed medical/surgical adult intensive care unit. Critical-Care Pain Observation Tool scores were abstracted for the 24 hours before and after initiation of authorized agent-controlled analgesia. Authorized agent-controlled analgesia was administered by nurses only. RESULTS The mean (SD) change in pain score was -3.4 (2.0) (95% CI, -4.0 to -2.7), representing a 69% decrease in the mean (SD) pain score from before to after initiation of authorized agent-controlled analgesia (4.8 [1.8] vs 1.5 [1.6]; P < .001). When the results were controlled for time, sedative administration, and opioid medication administration, the effect of authorized agent-controlled analgesia initiation on pain scores remained significant (P < .001). CONCLUSIONS Use of authorized agent-controlled analgesia is associated with a reduction in pain in critically ill patients. Larger studies are warranted to confirm these findings.
Net Section Fracture Assessment of Welded Rectangular Hollow Structural Sections

Rectangular Hollow Sections (RHS) because of their high resistance to tension, as well as compression, are commonly used as a bracing member with slotted gusset plate connections in steel structures. Since in this type of connection only part of the section contributes in transferring the tensile load to the gusset plate, shear lag failure may occur in the connection. The AISC specification decreases the effective section net area by a factor to consider the effect of shear lag for a limited connection configuration. This study investigates the effective parameters on the shear lag phenomenon for rectangular hollow section members connected at corners using a single concentric gusset plate. The results of the numerical analysis show that the connection length and connection eccentricity are the only effective parameters in the shear lag, and the effect of gusset plate thickness is negligible because of the symmetric connection. The ultimate tensile capacity of the suggested connection in this study were compared to the typical RHS connection presented in the AISC and the similar double angle sections connected at both legs. The comparison indicates that tensile performance of the suggested connection in this study because of its lower connection eccentricity is much higher than the typical slotted connection and double angle connections. Therefore, a new equation is suggested based on the finite element analyses to modify the AISC equation for these connections.
The effects of nutrient limitations on microbial respiration and organic matter decomposition in a Florida Spodosol as influenced by historical forest management practices

Abstract Recent investigations on the mechanistic underpinnings for nutrient regulated organic matter decomposition suggest that micronutrients may limit microbial activity in nitrogen (N) enriched forest ecosystems. However, these nutrient limitations could be complex for managed pine plantations in the US South that received macro- and micronutrient fertilization and weed control treatments. Soils and pine litter from second rotation loblolly pine stands were incubated to study the legacy effects of long-term silvicultural treatments [30+ years − Untreated Carryover (C) − Control (CC), Fertilization (CF), Fertilization + Weed control (CFW), Weed control (CW)] on microbial respiration and organic matter decomposition. These legacy treatment effects were contrasted with soils and litter corresponding to the current rotation’s actively managed treatments that were the same as in the first rotation (Actively managed retreated- C, F, FW, W). In general, both past rotation (CF: 17.9 μg C g−1 soil day−1) and current rotation fertilizer treatments (F: 22.3 μg C g−1 soil day−1) resulted in higher microbial respiration rates compared to their respective controls (CC: 11.9 μg C g−1 soil day−1; C: 12.5 μg C g−1 soil day−1), which likely reflected an inherently higher soil carbon content. Carbon normalized microbial respiration rates during the incubation period followed exponential decay patterns, with lower decay rates in fertilized soils compared to the average among treatments. Furthermore, N + phosphorus (P) additions suppressed microbial respiration in the CF and F treatments, but accelerated it in the CC and C treatments. This observation suggests that during the early stages of decomposition, N and P were limiting to microorganisms in those soils without a silvicultural treatment history. Positive microbial respiration response to added Cu for the CC and C, and added Mn for the CC, C, and W treatments suggested micronutrient limitations to microbial decomposition processes. For soils without a fertilization history, Mn peroxidase activity response to Mn addition levels followed the trend: high level > low level = No addition (CC and CW: p = 0.0032; C and W: p
Examining healthcare transition experiences among youth living with HIV in Atlanta, Georgia, USA: a longitudinal qualitative study.

Introduction Virtually all youth living with HIV in paediatric/adolescent care must eventually transition to adult-oriented HIV care settings. To date, there is limited evidence examining the perspectives of youth living with HIV longitudinally through the healthcare transition process. The objective of our study was to examine attitudes and experiences of youth living with HIV regarding healthcare transition, including potential change in attitudes and experiences over time. Methods We conducted a longitudinal qualitative interview study within a large, comprehensive HIV care centre in Atlanta, Georgia, USA between August 2016 and October 2019.We interviewed 28 youth living with HIV as part of a longitudinal observational cohort study of youth undergoing healthcare transition. We conducted qualitative interviews both immediately prior to, and one year following the transition from paediatric to adult-oriented care. Results Six distinct themes emerged from interviews conducted with youth living with HIV pre-transition: (1) reluctance to transition; (2) paediatric spaces as welcoming, and adult spaces as unwelcoming; (3) varying levels of preparation for transition; and (4) expectation of autonomy in the adult clinic. Analysis of post-transition interviews with the same youth demonstrated: (1) inconsistencies in the transition experience; (2) fear and anxiety about transition quelled by experience; (3) varying reactions to newfound autonomy and (4) communication as the most valuable facilitator of successful transition. Conclusions This study's longitudinal perspective on the healthcare transition experience yields insights that can be incorporated into programming targeting this critically important population. Although our study was conducted in a USA-based clinic with co-located paediatric and adult care services, many of our findings are likely to have relevance in other settings as well. Interventions aiming to improve HIV care engagement through transition should seek to enhance patient-provider communication in both paediatric and adult clinics, improve preparation of patients in paediatric clinics and ease patients gradually into autonomous disease management.
Evaluation of Volatility and Thermal Stability in Monomeric and Dimeric Lanthanide(III) Complexes Containing Enaminolate Ligands

Treatment of 3 equiv of the potassium salts derived from the β-amino ketones 1-(dimethylamino)-3,3-dimethylbutan-2-one (L1H), 3,3-dimethyl-1-(pyrrolidin-1-yl)butan-2-one (L2H), and 3,3-dimethyl-1-(...
Evaluation of length-lex set variables

This paper presents the first experimental evaluation of the length-lex domain for set variables. The implementation is based on bound-consistency algorithms proposed in earlier work and two novel technical contributions: a generic filtering algorithm which automatically pushes ordering constraints into symmetric binary constraints with only a logarithmic overhead and an adaptation of symmetry-breaking constraints from 0/1 matrices to the length-lex ordering. The experimental results indicate that the length-lex representation for set variables is very effective and robust on traditional set-CSPs benchmarks.
One substance, two liquids?

Water, like any other liquid, can be cooled below its freezing point without crystallizing. The physical properties of supercooled water are unusual: the lower its temperature, the easier it is to compress, and the more pronounced its anomalous tendency to expand when cooled. As if these characteristics were not peculiar enough, there is now evidence for the coexistence of two different forms of supercooled water. A phase transition between two liquid forms of a pure substance has never been observed before.
Metal Reconstitution of Particulate Methane Monooxygenase and Heterologous Expression of the pmoB Subunit

Particulate methane monooxygenase (pMMO) is a multisubunit metalloenzyme complex used by methanotrophic bacteria to oxidize methane in the first step of carbon assimilation and energy production. In this chapter, we detail methods to prepare metal free (apo) membrane-bound pMMO and to reconstitute apo pMMO with metal ions. We also describe protocols to clone, express, and refold metal-loaded soluble domain constructs of the pmoB subunit. These approaches were used to address fundamental questions concerning the metal content and location of the pMMO active site.
The Economics of the Microsoft Case

This paper explains the economics of Microsoft's anticompetitive actions, both the goal of suppressing Schumpeterian competition and the methods of denying widespread distribution to innovative new technologies. An understanding of the economics of the industry supports the logic of the government's antitrust case against Microsoft. Competition in the short run is limited by the network effects surrounding products like Microsoft Windows. Competition in the long run is far more feasible, but not automatic. The purpose of Microsoft's anticompetitive actions was to prevent widespread distribution of innovative technologies whose market success would have fostered long run competition. With that analysis in hand, this paper examines the effects of Microsoft's anticompetitive acts on the industry to determine whether and how the suppression was harmful to users of computers.
Credible enticements: Can host governments tailor multinational firms' organizations to suit national objectives?

Abstract This article discusses the impact of host government policy inconsistency on multinational corporations' relationships with local suppliers that benefit from public funding. Empirical findings suggest that such relationships suffer from transactions cost disadvantages, due to concerns that unexpected losses of funding may cause the suppliers to demand new contracts. The findings reflect statistical tests on a structural equation, latent variable model using data from a survey of 111 affiliates of MNCs operating in 36 countries.
Learning to be funny in Spanish during study abroad: L2 humor development

The present study examines an area of SLA that has to date received little attention: the development of L2 humor. Both creation and comprehension of humor in an L2 can be challenging for learners, even those with advanced proficiency (e.g., Bell, 2005; Shardakova, 2010). At the same time, learners at all proficiency levels have been shown to use L2 humor and research suggests that with increased proficiency and exposure to the language, learners can develop their L2 humor abilities (Bell, 2005; Davies, 2003, 2005; Shardakova, 2010). Previous research, however, has not examined the processes by which L2 learners develop their humor skills. Using a language socialization framework, the present article analyzes a case study of one study abroad student who developed his ability to be funny in Spanish conversations with age peers during one semester in Spain. Factors that may have been associated with a reduction in failed humor over time included developing friendships, eliminating deadpan humor, and revoicing the words, expressions, and ways of speaking in the L2 to which the learner was exposed during study abroad.
Localization and Functional Analysis of CHIP28k Water Channels in Stably Transfected Chinese Hamster Ovary Cells

CHIP28 is a major water transporting protein in erythrocytes and plasma membranes in kidney proximal tubule and thin descending limb of Henle. Chinese hamster ovary cells were stably transfected with the coding sequence of cloned rat kidney CHIP28k using expression vectors containing cytomegalovirus or Rous sarcoma virus promoters. Clonal cell populations expressed a 1.3-kilobase mRNA on Northern blot probed by CHIP28k cDNA and a 28-kDa protein on immunoblot probed by a polyclonal CHIP28 antibody. The clone with greatest expression produced approximately 8 x 10(6) copies of CHIP28k protein/cell. Plasma membrane osmotic water permeability (Pf), measured by stopped-flow light scattering, was 0.004 cm/s in control (vector-transfected) cells (10 degrees C) and 0.014 cm/s in the CHIP28k-transfected cells. Pf in CHIP28k-transfected cells had an activation energy of 4.9 kcal/mol and was reversibly inhibited by HgCl2. CHIP28k expression did not affect the transport of protons and the small polar non-electrolytes urea and formamide. CHIP28k immunoreactivity and function was then determined in subcellular fractions. Pf in 6-carboxyfluorescein-labeled endocytic vesicles, measured by a stopped-flow fluorescence quenching assay, was 0.002 cm/s (control cells) and 0.011 cm/s (CHIP28k-transfected cells); Pf in transfected cells was inhibited by HgCl2. Immunoblotting of fractionated endoplasmic reticulum, Golgi, and plasma membranes revealed high densities of CHIP28k (approximately 5000 monomers/microns 2 in plasma membrane) with different glycosylation patterns; functional water transport activity was present only in Golgi and plasma membrane vesicles. Antibody detection of CHIP28k by confocal fluorescence microscopy and immunogold electron microscopy revealed localization to plasma membrane and intracellular vesicles. These studies establish a stably transfected somatic cell line that strongly expresses functional CHIP28k water channels. As in the original proximal tubule cells, the expressed CHIP28k protein is a selective water channel that is functional in endocytic vesicles and the cell plasma membrane.
Formation of different framework structured dimeric dianions formed from the reduction of 2,4,6-tricyano-1,3,5-triazine and 1,3,5-tricyanobenzene

Reduction of 2,4,6-tricyano-1,3,5-triazine (1) and 1,3,5-tricyanobenzene (2) leads to dianionic dimers with long, ∼1.57 A, central C–C bonds. In contrast to 1, which dimerizes at the nitrile substituted carbon, 2 has a different motif as it dimerizes at the hydrogen substituted carbon.
Identification of an essential active-site residue in the α-D-phosphohexomutase enzyme superfamily.

Enzymes in the α-d-phosphohexomutase superfamily catalyze the conversion of 1-phosphosugars to their 6-phospho counterparts. Their phosphoryl transfer reaction has long been proposed to require general acid–base catalysts, but candidate residues for these key roles have not been identified. In this study, we show through mutagenesis and kinetic studies that a histidine (His329) in the active site is critical for enzyme activity in a well-studied member of the superfamily, phosphomannomutase/phosphoglucomutase from Pseudomonas aeruginosa. Crystallographic characterization of an H329A mutant protein showed no significant changes from the wild-type enzyme, excluding structural disruption as the source of its compromised activity. Mutation of the structurally analogous lysine residue in a related protein, phosphoglucomutase from Salmonella typhimurium, also results in significant catalytic impairment. Analyses of protein–ligand complexes of the P. aeruginosa enzyme show that His329 is appropriately positioned to abstract a proton from the O1/O6 hydroxyl of the phosphosugar substrates, and thus may serve as the general base in the reaction. Histidine is strongly conserved at this position in many proteins in the superfamily, and lysine is also often conserved at a structurally corresponding position, particularly in the phosphoglucomutase enzyme sub-group. These studies shed light on the mechanism of this important enzyme superfamily, and may facilitate the design of mechanism-based inhibitors. Database Structural data have been deposited in the Protein Data Bank with accession number 4IL8.
CHARACTERISTICS OF A LOW F-NUMBER BROADBAND VISIBLE THERMAL OPTICAL LIMITER

The operation of a wide field-of-view optical limiter is described for self-defocusing type nonlinear refractive materials, and design strategies were developed with the aid of numerical modeling. Experiments with a cell thickness on the order of the Rayleigh length (25–100 µm) were conducted with 6 and 30 nsec pulse lengths (single shot) at a wavelength of 532 nm. Broadband optical limiting with the transmitted fluence below the eye MPE (maximum permissible exposure) level was achieved using nigrosin dye dissolved in CS2, owing to the large thermal nonlinearity of the solvent, and the large changes in the refractive index allowed by a liquid. The device performance was accurately predicted by the numerical model up to the point of dielectric breakdown. Using 6 nsec pulses, we measured a limiting threshold energy of 40 nJ, which corresponds to a fluence of only 100 mJ/cm2 in the solution, in an f/5 optical system with neutral gray transmission of ~ 50%.
An analysis of simple two‐stage voting systems

This paper examines two-stage voting procedures [x,k,y] at the level either of a local governmental organization or of a national governmental system in which x is the number of candidates a voter is to vote for on the first ballot, k is the number of candidates to be placed on the second ballot according to the greatest vote totals from the first ballot, and y is the number of the k candidates on the second ballot that a voter is to vote for on the second ballot. The winner is the candidate with the most votes on the second ballot. These systems are practical in many situations and correspond to many two-stage voting systems in current use. The main purpose of the paper is to assess the propensities of alternative two-stage systems to elect the candidate which would be elected by a theoretically more sophisticated but less practical norm procedure such as simple majority of the Borda sum-of-ranks method. Extensive computer simulation, restricted to three to ten candidates but allowing a variety of methods by which voter preferences are randomly generated, reveals that the best propensity maximizing two-stage system has the form [x,2,1] in which exactly two candidates appear on the second ballot. Under the restriction that a voter is to vote for only one candidate on each ballot, the best system is common double plurality [1,2,1]. Without this restriction the best system usually has x = 2, with x approximately equal to the optimal number of candidates to vote for on the single ballot in a one-stage election in which the winner is determined by the greatest number of votes from the single ballot.
Smoothed Particle Hydrodynamics Simulations of Counterrotating Disk Formation in Spiral Galaxies

We present the results of smoothed particle hydrodynamics (SPH) simulations of the formation of a massive counterrotating disk in a spiral galaxy. The current study revisits and extends (with SPH) previous work carried out with sticky particle gas dynamics, in which adiabatic gas infall and a retrograde gas-rich dwarf merger were tested as the two most likely processes for producing such a counterrotating disk. We report on experiments with a cold primary similar to our Galaxy, as well as a hot, compact primary modeled after NGC 4138. We have also conducted numerical experiments with varying amounts of prograde gas in the primary disk and an alternative infall model (a spherical shell with retrograde angular momentum). The structure of the resulting counterrotating disks is dramatically different with SPH. The disks we produce are considerably thinner than the primary disks and those produced with sticky particles. The timescales for counterrotating disk formation are shorter with SPH, because the gas loses kinetic energy and angular momentum more rapidly. Spiral structure is evident in most of the disks, but an exponential radial profile is not a natural by-product of these processes. The infalling gas shells that we tested produce counterrotating bulges and rings rather than disks. The presence of a considerable amount of preexisting prograde gas in the primary causes, at least in the absence of star formation, a rapid inflow of gas to the center and a subsequent hole in the counterrotating disk. For a normal counterrotating disk to form, there must be either little or no preexisting prograde gas in the primary, or its dissipative influence must be offset by significant star formation activity. The latter scenario, along with the associated feedback to the interstellar medium, may be necessary to produce a counterrotating disk similar in scale length and scale height to the primary disk. In general, our SPH experiments yield stronger evidence to suggest that the accretion of massive counterrotating disks drives the evolution of the host galaxies toward earlier (S0/Sa) Hubble types.
Methionine-enkephalin stimulates gastric secretion and gastric mucosal blood flow.

SummaryIntra-arterial infusion of methionine–enkaphalin or morphine caused a dose-dependent increase in histamine-induced gastric secretion and gastric mucosal blood flow. Administration of naloxone resulted in the reduction of both gastric secretion and mucosal circulation indicating that oxyntic cells possess specific opiate receptors and that opiate peptides may be involved in the stimulation of gastric secretion.
Identification of gaps in mangrove forests with airborne LIDAR

Abstract Mangrove forests change frequently due to disturbances from tropical storms, frost, lightning, and insects. It has been suggested that the death and regeneration of trees in small gaps due to lightning may play a critical role in mangrove forest turnover; however, the large-scale quantification of spatial pattern and areas of gaps is lacking for investigating this issue. Airborne light detection and ranging (LIDAR) technology provides an effective way for identifying gaps by remotely obtaining direct measurements of ground and canopy elevations. A method based on an alternative sequential filter and black top-hat mathematical morphological transformation was developed to extract gap features. Comparison of identified gap polygons with raw LIDAR measurements and field surveys shows that the proposed method successfully extracted gap features in mangrove forests in Everglades National Park. There are 400–500 lightning gaps per square kilometer in mangrove forests at the study sites. The distribution of gap sizes follows an exponential form and the area of gaps with sizes larger than 100 m2 account for 55–61% of the total area of gaps. The area of gaps in the mangrove forest in Everglades National Park is about 4–5% of the total forest area and the average gap formation rate is about 0.3% of the total forest area per year, indicating that lightning gaps play an important role in mangrove forest dynamics.
A Hybrid ETKF–3DVAR Data Assimilation Scheme for the WRF Model. Part II: Real Observation Experiments

Abstract The hybrid ensemble transform Kalman filter–three-dimensional variational data assimilation (ETKF–3DVAR) system developed for the Weather Research and Forecasting (WRF) Model was further tested with real observations, as a follow-up for the observation system simulation experiment (OSSE) conducted in Part I. A domain encompassing North America was considered. Because of limited computational resources and the large number of experiments conducted, the forecasts and analyses employed relatively coarse grid spacing (200 km) to emphasize synoptic scales. As a first effort to explore the new system with real observations, relatively sparse observation datasets consisting of radiosonde wind and temperature during 4 weeks of January 2003 were assimilated. The 12-h forecasts produced by the hybrid analysis produced less root-mean-square error than the 3DVAR. The hybrid improved the forecast more in the western part of the domain than the eastern part. It also produced larger improvements in the upper tr...
Lower bound for the connective constant of a self-avoiding walk on a square lattice

Abstract It is shown that 2.58105 lim k→∞ c k 1 k , where ck is the number of self-avoiding walks on the square lattice of k steps which start at the origin; this is the best lower bound so far calculated. The bound is obtained by use of a theorem of Kesten and computer enumeration of walks.
Long-term oral anticoagulant therapy in patients with unstable angina or suspected non-Q-wave myocardial infarction

To the Editor: A striking thing that emerges from the report by Anand et al of the OASIS pilot study1 relates to the differences in the control arms in phase 1 (randomization to coumadin or standard care a mean of 6 days after study entry) and phase 2 (randomization to coumadin or standard care a mean of 26 hours after study entry). It is difficult to reconcile why the placebo composite event rate of cardiovascular death/new myocardial infarction/refractory angina at 6 months in phase 1 (3.9%) is so much lower than the placebo composite event rate at 3 months in phase 2 (12.1%). How can getting placebo early or late …
Construct validity of parent ratings of inhibitory control.

Recent literature has emphasized the need to examine executive functions (EF) in children using multiple sources, including both parent rating and performance-based measures. Computerized Go/No-Go tests, including commercially available continuous performance tests (CPTs), represent one of the most commonly used methods of assessing inhibitory control—a variable central to the executive function construct. We examined the relationship between parent ratings of inhibitory control and CPT performance in two mixed clinical samples. Experiment 1 examined 109 children ages 6–18 using the Behavior Rating Inventory of Executive Function (BRIEF; Gioia, Isquith, Guy, & Kenworthy, 2000) and the Conners' CPT-II (Conners, 2000). In this sample, ratings on the BRIEF Inhibit scale (mean T-score = 62.3) were significantly higher than the CPT-II commissions score (mean T-score = 50.7; p < .0001); and the BRIEF and CPT-II scores were not highly correlated (r = − .12). Experiment 2 examined a sample of 131 children ages 7–...
Endogenous nitric oxide is required for tonic cholinergic inhibition of spinal mechanical transmission

Recent studies have suggested that a spinal cholinergic system is important in spinal nociceptive modulation. In the present study, the role of a nitric oxide (NO)-generating system in spinal cholinergic modulation of nociception was examined in awake rats. Intrathecal (i.t.) administration of the cholinergic muscarinic receptor antagonist atropine produced a dose-dependent (1.4-14.4 nmol) decrease in the mechanical threshold for tail withdrawal, which was reversed rapidly (2-3 min) by subsequent i.t. administration of the NO precursor, L-arginine (10 pmol to 10 nmol). Intrathecal administration of L-arginine alone (10 pmol to 10 nmol) produced a dose-dependent increase in the mechanical nociceptive withdrawal threshold of the tail. The reflexive withdrawal of the tail produced by noxious heat was not significantly affected by i.t. administration of either atropine or L-arginine. Inhibition of the NO-cGMP pathway by i.t. administration of either Nw-nitro-L-arginine methyl ester (L-NAME, 10 nmol) or methylene blue (10 nmol) significantly enhanced the magnitude and prolonged the time course of the decrease in the mechanical threshold for tail withdrawal produced by i.t. pretreatment with atropine (1.4 nmol). Neither L-NAME nor methylene blue affected mechanical withdrawal thresholds in rats pretreated with saline. These data suggest that the production of endogenous NO is required for tonic inhibition of spinal nociceptive mechanical transmission. Moreover, the present data support the speculation that there exists in the lumbar spinal cord a tonic, cholinergic modulation of NO synthase.
On the complexity of a pivot step of the revised simplex algorithm

Abstract A modification of the revised simplex algorithm is considered where every step involves O(m2) arithmetical operations. The error analysis and the bit-complexity estimates presented show very strong stability of the modified algorithm. The same modification can be included into some other linear algebra algorithms.
Early Growth Response 1 (Egr1) Regulates Cholesterol Biosynthetic Gene Expression

The early growth response (EGR) family of transcription factors has been implicated in control of lipid biosynthetic genes. Egr1 is induced by insulin both in vitro and in vivo and is the most highly expressed family member in liver. In this study, we investigated whether Egr1 regulates cholesterol biosynthetic genes in liver. Using an insulin-sensitive liver cell line, we show that localization of Egr1 to cholesterol biosynthetic genes is induced by insulin treatment and that this localization precedes the induction of the genes. Reduction in Egr1 expression using targeted siRNA blunted the insulin-dependent induction of cholesterol genes. A similar reduction in squalene epoxidase expression was also observed in Egr1 null mice. In addition, application of chromatin immunoprecipitation (ChIP) samples to tiled gene microarrays revealed localization of Egr1 in promoter regions of many cholesterol gene loci. In vivo ChIP assays using liver tissue show that Egr1 localization to several cholesterol biosynthetic gene promoters is induced by feeding. Finally, analysis of plasma cholesterol in Egr1−/− mice indicated a significant decrease in serum cholesterol when compared with wild-type mice. Together these data point to Egr1 as a modulator of the cholesterol biosynthetic gene family in liver.
Consistency in relation to inter-subject congruity in the loci of stutterings.

Abstract The congruity between subjects in the distribution of stuttered words in reading passage was far less than the subjects' self-consistency in two readings of the passage. Of the words stuttered by a given subject in the second reading, the average percentage which had been stuttered by the same subject in the first reading was 48. By contrast, the percentage which was stuttered by another subject, on the average, was only 18. Apparently, certain individual factors are considerably more powerful in determining which words are stuttered in repeated readings than are the group factors which have generally been related to the loci of stutterings.
A bistable mechanism for chord extension morphing rotors

Research efforts have shown that helicopter rotor blade morphing is an effective means to improve flight performance. Previous example of rotor blade morphing include using smart-materials for trailing deflection and rotor blade twist and tip twist, the development of a comfortable airfoil using compliant mechanisms, the use of a Gurney flap for air-flow deflection and centrifugal force actuated device to increase the span of the blade. In this paper we explore the use of a bistable mechanism for rotor morphing, specifically, blade chord extension using a bistable arc. Increasing the chord of the rotor blade is expected to generate more lift-load and improve helicopter performance. Bistable or "snap through" mechanisms have multiple stable equilibrium states and are a novel way to achieve large actuation output stroke. Bistable mechanisms do not require energy input to maintain a stable equilibrium state as both states do not require locking. In this work, we introduce a methodology for the design of bistable arcs for chord morphing using the finite element analysis and pseudo-rigid body model, to study the effect of different arc types, applied loads and rigidity on arc performance.
Alfvenic motions in the solar atmosphere.

Discussion of the amplitude of bulk velocities associated with upward-propagating Alfven waves in the lower solar atmosphere. It is shown that, for a given wave energy flux, the bulk velocities can be appreciably lower in cases when the wavelength is much larger than the scale height, than in situations where the wavelength is smaller than the scale height.