cssi/SciSciGPT-SciSciNet huggingface dataset:
Surface effects in Debye screening

A thermodynamic system of equally charged, plus and minus, classical particles constrained to move in a (spherical) ball is studied in a region of parameters in which Debye screening takes place. The activities of the two charge species are not taken as necessarily equal. We must deal with two physically interesting surface effects, the formation of a surface charge layer, and long range forces reaching around the outside of the spherical volume. This is an example in as much as 1) general charge species are not considered, 2) the volume is taken as a ball, 3) a simple choice for the short range forces (necessary for stability) is taken. We feel the present system is general enough to exhibit all the interesting physical phenomena, and that the methods used are capable of extension to much more general systems. The techniques herein involve use of the sine-Gordon transformation to get a continuum field problem which in turn is studied via a multi-phase cluster expansion. This route follows other recent rigorous treatments of Debye screening.
Homozygous mutation in SCN5A associated with atrial quiescence, recalcitrant arrhythmias, and poor capture thresholds.

Case report A 6-year-old Hispanic girl was referred to cardiology for irregular heartbeats. On electrocardiogram (ECG), she was noted to have sinus bradycardia with nonspecific intraventricular conduction delay, as well as frequent sinus pauses with junctional escape on Holter monitoring. Despite multiple attempts to contact her, she did not follow up, and at 11 years of age collapsed while running at school. She was unresponsive, and an automated external defibrillator determined her rhythm to be “shockable” ventricular tachycardia. After defibrillation, perfusion was re-established, and she was taken to a local emergency room, where a lidocaine infusion was initiated with temporary stabilization in her rhythm. While in the emergency room, she had recurrent episodes of unstable, sustained ventricular tachycardia, requiring 6 separate cardioversions and ongoing cardiopulmonary resuscitation. A chest radiograph showed moderate cardiomegaly. Electrocardiography revealed no discernible atrial activity, with a slow junctional escape and frequent premature ventricular contractions (Fig. 1). It also revealed low-voltage QRS complexes and a prolonged QT interval, although this was after cardiac arrest. Subsequent telemetry revealed frequent episodes of polymorphic ventricular tachycardia. An echocardiogram was performed, which revealed severely depressed biventricular function (ejection fraction 19%), with normal anatomy and coronary origins. Because of recurrent episodes of ventricular tachycardia/ventricular fibrillation, she was transitioned to an amiodarone infusion. She was transferred to our institution and was ultimately placed on extracorporeal membrane oxygenation for recalcitrant arrhythmias and progressive metabolic acidosis. In the operating room, it was noted that her atria were dilated and not contracting.
Room-temperature molecular-resolution characterization of self-assembled organic monolayers on epitaxial graphene

Graphene, a two-dimensional sheet of carbon atoms, is a promising material for next-generation technology because of its advantageous electronic properties, such as extremely high carrier mobilities. However, chemical functionalization schemes are needed to integrate graphene with the diverse range of materials required for device applications. In this paper, we report self-assembled monolayers of the molecular semiconductor perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA) formed on epitaxial graphene grown on the SiC(0001) surface. The molecules possess long-range order with a herringbone arrangement, as shown by ultra-high vacuum scanning tunnelling microscopy at room temperature. The molecular ordering is unperturbed by defects in the epitaxial graphene or atomic steps in the underlying SiC surface. Scanning tunnelling spectra of the PTCDA monolayer show distinct features that are not observed on pristine graphene. The demonstration of robust, uniform organic functionalization of epitaxial graphene presents opportunities for graphene-based molecular electronics and sensors.
Dispersion-managed solitons in a fiber loop with in-line filtering.

We investigate both numerically and experimentally soliton propagation in a fiber loop with dispersion management, in-line filters, and frequency shifting. More than 90% of the fiber in the loop is in the normal-dispersion regime, but the net dispersion is anomalous. Stable pulses in the loop have an enhanced power relative to solitons in a fiber with uniform dispersion equal to the loop’s path-averaged dispersion. Because the loop’s path-averaged dispersion is small, the in-line filtering and the frequency shifting play an important role in pulse shaping. Recirculating loop experiments that demonstrate stable pulse propagation over 28,000 km are consistent with results from computer modeling.
Constraints on cosmologically regenerated gravitinos

Abstract Cosmological constraints on the regenerated abundance of gravitinos as a function of the maximum reheating temperature T h are examined. We combine the bound that arises in order for stable photinos produced by gravitino decays to not overdominate the mass density of the universe together with that inferred from the distortions produced in the cosmic microwave background radiation as well as constraints from the observed deuterium and 3 He abundances. This suffices to constrain T h to be below between 10 17 and 10 10 GeV for gravitions in the mass below ∼ 10 TeV. More massive gravitinos, however, could be produced at T h 14 GeV.
Accessing ICLAS Network Log Data to Study Student Computer Usage, Course Performance, and Attitude Change

ABSTRACT This study demonstrated how network usage logs such as those generated by the IBM Classroom Local Area Network Administration System (ICLAS) can be used to study student use of software available on a local area network. Software instrumentation was developed to convert ICLAS log files to a format (∗.DIF) usable by spreadsheet and statistics software. Data on 163 students enrolled in an ‘Introduction to Computers in Education’ course during the Summer, 1992 session at the University of South Florida were compiled for exploratory analysis. Correlations of lab use time to course grade, change in knowledge, and change in attitude were performed. It was found that amount of lab use correlated significantly to general attitude toward computers, but that it did not correlate significantly to change in attitude toward school uses of computers or to change in knowledge of course topics.
Management of Posterior Urethral Valves on the Basis of Urodynamic Findings

AbstractPurpose: Abnormal urodynamic findings are common in boys with a history of posterior urethral valves. However, to our knowledge there are few reports on the results of treating these abnormal findings. We analyzed the treatment of abnormal urodynamic parameters and its outcome in 21 boys who underwent valve ablation.Materials and Methods: After valve ablation multichannel urodynamic studies were performed in 31 boys, including 21 in whom studies were done before and after therapy was started for abnormal parameters. Detrusor instability and impaired bladder compliance were treated with anticholinergics or augmentation cystoplasty, and impaired detrusor contractility was managed with clean intermittent catheterization.Results: Before therapy 17 of 21 boys had impaired compliance and detrusor instability, 2 had impaired compliance without instability and 2 had instability alone. After treatment 8 boys had impaired compliance and 4 had detrusor instability. After anticholinergics were initiated new o...
Free sorting with stimuli clustered in a multidlmensional attribute space

An experiment was conducted to determine whether Ss leam, without knowledge of results or prior familiarization with the prototypes, to sort histoform stimuli generated by three probablistic rules into categories consistent with these mies. Seven Ss were asked to sort 30 stimuli (10 from each schema population) on each trial. No constraints were placed on the number of categories to be used. A statistic was developed to measure consistency between schema-defined categories and subjeet-defined categories. Four of the seven Ss met the leaming criterion, and demonstrated increasing consistency with the schema-defined categories across trials. In general, more categories than necessary were used to classify the stimuli correctly. The results raise several questions about classification strategies used by Ss in perceptual learning tasks with stimuli generated by probabilistic rules, and indicate the need for further research conceming the variables that influence perceptual category formation.
Flow-Field Study in a Microjet PEM Fuel Cell

Microjets have been implemented into a PEM fuel cell in an attempt to achieve even distribution of reactants and passive cooling of the fuel cell unit and a preliminary investigation of this application has yielded positive results. Unlike conventional reactant supply, the reactant microjets impinge on the back side of the flow field plate before wrapping around and traversing the flow field channels where they are involved in electrochemical activity. However, it was observed that the fuel cell was subject to significant flooding, which limited its continuous operation. This paper discusses the results from an experimental study that has been carried out in an attempt to reduce or eliminate the occurrence of flooding through the use of two different flow-field configurations. Measurements of these flow field configurations, identified as MJFC I and MJFC II, are presented here. MJFC I, the first generation prototype, uses a variant of parallel flow field while MJFC II, the second generation prototype, uses multiple independent serpentine flow field channels. For similar operating conditions, characteristic curves obtained showed that MJFC I is susceptible to flooding while MJFC II has superior water management capability. Secondary tests using Electrode Impedance Spectroscopy confirm these findings.Copyright © 2010 by ASME
Hard Times in the Marvelous City: From Dictatorship to Democracy in the Favelas of Rio de Janeiro

Brazil entered the modern republican period of history in 1889 under the slogan of ‘order and progress’, meaning economic progress for the elites, and police order, physical expulsion and spatial s...
The photolysis of ozone

Ozone was photolyzed at 25 C with steady illumination at several wavelengths from 2288 to 2850 A, at O3 pressures from 0.1 to 2.7 torr, and at absorbed intensities from 0.15 to 65 microns/min. Experiments were done in pure dry O3, and in the presence of He, CO2, N2, H2O, H2, N2O, He-CO2, He-H2O, CO2-H2O, O2-N2O, CO2-O2, and N2O5-O2-CO2 mixtures. The results show that in the absence of added gases or in the presence of He, the quantum yield of O3 consumption is 5.5 independent of conditions, except at pressures below 0.4 torr. In the presence of CO2 or N2, ozone consumption falls toward 4.0. The primary photolytic act produces O(1 D) and siglet O2, presumably O2(1 delta), at all wavelengths below 3000 A. Relative quenching constants O(1 D) removal by various gases were measured at 2288, 2537, and 2800 A. For O3, CO2, and N2, the relative rates are 1.0/0.4 to 0.5/0.08 to 0.11 at all wavelengths. For H2O the constant at 2537 A is 1.5 relative to that for O3. With N2O, a noticeable wavelength effect is observed and the relative rate constants are 1.5, 2 to 3, 4.0 for O3 compared to N2O at 2800, 2537, and 2288 A, respectively.
Paternal Work Stress and Latent Profiles of Father-Infant Parenting Quality.

The current study used latent profile analysis (LPA) to examine the implications of fathers’ experiences of work stress for paternal behaviors with infants across multiple dimensions of parenting in a sample of fathers living in nonmetropolitan communities (N = 492). LPA revealed five classes of fathers based on levels of social-affective behaviors and linguistic stimulation measured during two father-infant interactions. Multinomial logistic regression analyses suggested that a less-supportive work environment was associated with fathers’ membership in multiple lower-quality parenting classes. Greater work pressure and a nonstandard work schedule also predicted fathers’ membership in the latent parenting classes, although these associations differed depending on the number of hours fathers spent in the workplace.
Comments on "Walsh Spectral Estimates with Applications to the Classification of EEG Signals"

Larsen and Lai1 present an empirical proof that Walsh spectral features classify EEG data in much the same way as the Fourier spectral analysis,1 despite contradictory results reported in [1]. It is the purpose of this comment to present additional information that may explain this discrepancy.
A study of the rat neuropeptide B/neuropeptide W system using in situ techniques

In the rat, the neuropeptide B/neuropeptide W (NPB/NPW) system is composed of two ligands, neuropeptide B (NPB) and neuropeptide W (NPW), and one receptor, GPR7. Although preliminary analyses show roles in feeding, hormone secretion, and analgesia, the lack of a detailed anatomical map impairs our understanding of the NPB/NPW system. We demonstrate in this report the expression patterns of GPR7, NPB, and NPW precursor messenger ribonucleic acid (mRNA) in the rat brain by using in situ hybridization and in situ binding experiments. The amygdala expresses the highest levels of GPR7 mRNA and binding signals. Other nuclei with high levels of expression and binding are the suprachiasmatic and the ventral tuberomamillary nuclei. Moderate levels are seen in the dorsal endopiriform, dorsal tenia tecta, bed nucleus, and the red nucleus. Low levels are in the olfactory bulb, parastrial nucleus, hypothalamus, laterodorsal tegmentum, superior colliculus, locus coeruleus, and the nucleus of the solitary tract. Although the NPB precursor is mostly expressed at low levels in the brain, moderate expression is seen in anterior olfactory nucleus, piriform cortex, median preoptic nucleus, basolateral amygdala, hippocampus, medial tuberal nucleus, substantia nigra, dorsal raphe nucleus, Edinger-Westphal nucleus, and the locus coeruleus. To our surprise, the expression of NPW precursor was not detected. Our study greatly expands the preliminary in situ data previously reported. With this map of the NPB/NPW system in the rat brain, a better understanding of the functional implications of the system in various behavioral paradigms is now possible.
Physiological changes during cold acclimation of perennial ryegrass accessions differing in freeze tolerance.

Perennial ryegrass (Lolium perenne L.) is a coolseason turfgrass species that can exhibit significant freezing injury in northern climatic regions. The objective of this study was to quantify major physiological and biochemical changes occurring during the cold acclimation period in four perennial ryegrass accessions varying in freezing tolerance (two freezing-tolerant accessions, TOL-1 and TOL-2, and two freezing-susceptible accessions, SUS-1 and SUS-2). Plants were subjected to a cold acclimation period of 2°C for 21 d in a controlled environment chamber. Crown tissues were harvested at 0, 7, 14, and 21 d of acclimation for determination of proline, water soluble carbohydrates (WSC), and lipid composition. Leaf photochemical efficiency (Fv/Fm) was also measured weekly before plant sampling for biochemical components. In general, proline levels increased and Fv/Fm decreased during cold acclimation; however, there were no differences in proline accumulation or Fv/ Fm among the accessions in response to cold acclimation. Water soluble carbohydrates significantly increased in response to 2°C, with TOL accessions (TOL-1 and TOL-2) accumulating higher WSC than SUS (SUS-1 and SUS-2) by 21 d of acclimation. There were also significant changes in major phospholipids classes at 2°C. Specifically, TOL-2 exhibited a higher ratio of membrane stabilizing lipids and unsaturated fatty acid content compared to SUS-1, SUS-2, and TOL-1 by 21 d of cold acclimation.
Heterogeneity of cholecystokinin/gastrin-like immunoreactivity in the nervous system of the nematode Ascaris suum

A wholemount immunocytochemical method was used for the localization of cholecystokinin (CCK8)-like and gastrin-like immunoreactivity in Ascaris. The patterns of specific neuronal staining given by two antisera and four monoclonal antibodies made against CCK8, and one antiserum made against gastrin were investigated. Preabsorption of these antibodies with CCK8 or gastrin 17 resulted in complete loss of immunoreactivity in almost all of the neurons (two antisera also contained nonspecific antibodies), suggesting that all of the antibodies recognize epitopes, in Ascaris neurons, that include some or all of the C-terminal five amino acids that are identical in CCK8 and gastrin 17. However, the seven different antibodies showed immunoreactivity in different subpopulations of neurons, implying that there are at least seven different species of CCK-like molecules in Ascaris. Fractionation of Ascaris peptide extracts by high performance liquid chromatography (HPLC), monitoring fractions with a CCK8 radioimmunoassay (RIA), also shows heterogeneity of molecules immunologically related to CCK8.
Intracellular acid phosphatase and lysozyme levels in subpopulations of oyster, Crassostrea virginica, hemocytes.

Abstract Five subpopulations of Crassostrea virginica hemocytes have been separated by employing a Percoll discontinuous density gradient. As reported previously (T. C. Cheng, J. W. Huang, H. Karadogan, L. R. Renwrantz, T. P. Yoshino, J. Invertebr. Pathol. 36, 35–40, 1980), cells comprising subpopulation 2 are hyalinocytes. Quantitative determinations of the activity levels of two lysosomal hydrolases, acid phosphatase and lysozyme, have revealed that granulocytes comprising subpopulation 4 show the highest levels, followed by granulocytes comprising subpopulation 3. This and an earlier report of several differences between members of subpopulations of oyster hemocytes suggest functional differences.
Surface-Initiated Activators Generated by Electron Transfer for Atom Transfer Radical Polymerization in Detection of DNA Point Mutation

Amplification-by-Polymerization reportedly offers a sensitive and detector-free approach for DNA detection. However, the requirement for an oxygen-free environment when classic radical polymerization reactions are used in signal amplification significantly limits the mobility of this approach for point-of-need applications. We report here the employment of a purge-free controlled/"living" polymerization reaction, activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), to achieve signal amplification upon DNA hybridization. Its aptitude in simplifying assay procedure and shortening assay turn-around has been demonstrated in this report, which substantiates the feasibility of using Amplification-by-Polymerization for high throughput or portable screening of genetic mutations. In addition, employment of water-soluble ascorbic acid as the reducing agent has overcome the hurdles encountered by heterogeneous AGET ATRP reactions. Optimization of AGET ATRP in the presence of oligonucleotides has been conducted where tris[(2-pyridyl)methyl]amine (TPMA) was selected as the catalyst ligand for its mild reaction rate. Effective polymer growth has been achieved when the concentration of the Cu(II) catalyst was controlled at 20 mM and ascorbic acid at 18 mM. The propagation and termination reaction constants have been derived, purporting the speculated controlled growth kinetics during polymer grafting. A linear relationship between the grafted polymer film thickness and the amount of captured DNA target sequences has been established, which provides the quantification basis during DNA detection. Detection of DNA sequences with single-point mutations has been successful regardless of the mutation site.
HIV gene expression enhances T cell susceptibility to hydrogen peroxide-induced apoptosis

A human T cell lineage was used to determine the possible effects of HIV infection on T cell antioxidant status. On inoculation into serum-free culture, 8E5, a constitutive HIV-expressing T cell line, underwent apoptosis whereas cell death was not observed with the uninfected A3.01 or latently HIV-infected 8E5L T cell lines. 8E5 survival was markedly prolonged by supplementing the serum-free medium with either A3.01-conditioned medium, catalase, vitamin E, or 2-mercaptoethanol, but supplementation with ascorbic acid, glutathione, or N-acetylcysteine had no effect. Consistent with their being in a state of oxidative stress, 8E5 cells displayed reduced levels of catalase activity, and were more susceptible to killing by exogenous hydrogen peroxide (H2O2) than A3.01 and 8E5L cells. These results demonstrate an inverse correlation between HIV gene expression and antioxidant status in human T cells. Enhanced cytotoxicity of HIV-infected, antioxidant-deficient CD4 T cells following exposure to H2O2 in lymphoid ...
Angiotensin II and retinal pericytes migration

Abstract Angiotensin II (Ang II) appears to participate in the regulation of neovascularization processes in the retina. Migration of perimural cells such as pericytes plays a key role in regulation of angiogenesis. We hypothesize that Ang II stimulates migration of retina pericytes. For this we studied the effects of Ang II on migration of bovine retinal pericytes using modified Boyden chambers and collagen IV-covered polyester membranes. Ang II stimulated migration of pericytes by 54.8 ± 9.7% (n = 10, p
Combination of laser and radar altimeter height measurements to estimate snow depth during the 2004 Antarctic AMSR‐E Sea Ice field campaign

[1] Among the most important parameters needed to evaluate the present and future state of Antarctic sea ice cover is the ice thickness. The retrieval of ice thickness using remote sensing techniques has been hampered by the absence of a capability to remotely measure snow thickness covering the sea ice. Data sets collected with Johns Hopkins Applied Physics Laboratory's Delay-Doppler Phase Monopulse (D2P) radar and NASA's Airborne Topographic Mapper (ATM) scanning lidar during NASA's Antarctic AMSR-E Sea Ice field campaign over the Bellingshausen Sea are used to demonstrate the potential of a remote-sensing technique for retrieval of snow cover thickness from an airborne platform. The technique takes advantage of the fact that the radar is most sensitive to the snow-ice interface while the lidar responds to the highly optically reflective snow surface. The difference between the radar- and laser-determined surfaces yields an estimate of snow thickness that appears to be reasonably consistent with expected values. The technique requires careful registration of the instrument footprints. Because there was no absolute range calibration of the lidar due to predeployment scheduling difficulties, the vertical offset between the instruments was resolved by determining the difference between measurements over leads. Elsewhere over sea ice the radar-defined surface is generally below the laser-defined surface consistent with the radar defining the snow-ice interface. Over a relatively small portion of the data, we observed opposite relationship between the sensor-defined surfaces for which we discuss a plausible physical explanation.
Single-crystal silicon: application to micro-opto-electromechanical devices

We demonstrate the fabrication of an out-of-the-plane Fabry-Perot interferometer (FPI) `on-a- chip' using the single crystal reactive etching and metallization (SCREAM) process. A modified version of this process is also developed to generate a fully suspended Fabry-Perot interferometer (FPI) `on-a-frame.' The optical device is mounted on a released frame, which includes suspended contact pads and oxide isolating segments. During the process, the total structure (with 8.6 mm 2 surface area) is fixed to the substrate through serpentine springs. Then, using a pair of fine tweezers, these springs are clipped and the thin membrane- like structure is lifted off the substrate and placed exactly between self-aligned input and output single-mode optical fibers. The suspended FPI `on-a-frame' is made from freely released beams of dimensions comparable to fiber diameter with a vertical depth of 107.5 micrometers . The mirrors of the FPI, which consist of a series of (lambda) /4 SiO 2 and Si film stacks separated by an initial gap distance of 10 micrometers , attract each other when a bias is applied across these capacitor-type plates and tune broad-band IR light into a specific wavelength.
RAP Project—An Instrument Development Study to Determine Common Attributes for Pain Assessment among Men and Women Who Represent Multiple Pain-Related Diagnoses

Abstract Inadequate pain assessment by nurses is a primary barrier to provision of optimum pain relief and may contribute, in part, to the epidemiologic health problem of unrelieved pain. In this three-phase study, both qualitative and quantitative methods were used to develop, revise, and test a multidimensional pain assessment instrument, theoretically supported for use with all adult patients experiencing pain, for the purpose of contributing to a systematic global approach to comprehensive pain assessment. In phase 1, instrument items were inductively derived from interviews of participants experiencing homogeneous pain. In phase 2, sensitivity of items to heterogeneous pain was established through focus groups and interviews of participants reporting multiple pain problems. In phase 3, psychometric properties were evaluated with subjects representing a variety of pain-related diagnoses. Cronbach’s alpha for the global score of the instrument was 0.89. Factor analysis indicated three domains of heterogeneous pain: “learning to live with pain” (nine items), “thinking and feeling pain” (fifteen items), and “perceiving controllability of pain” (six items). Triangulation of phase 3 item clusters with phase 2 data provided a framework for substantive interpretation of factors, identification of heterogeneous pain attributes, and validation of category themes that emerged in phase 1. Preliminary evidence supported initial reliability and validity, indicating sensitivity of the Richards Assessment of Pain (RAP) instrument to heterogeneous pain. Substantive interpretation of RAP factors revealed attributes of heterogeneous pain that may contribute to global pain assessment for all patients with pain.
Trident as an ultrahigh irradiance laser

The Trident Nd:glass ICF laser at Los Alamos National Lab may be operated in a mode that produces high energy ultrashort pulses by the chirp/compression method. The 125-ps pulses from a standard mode-locked, Nd:YLF oscillator are first frequency-broadened to 3-nm bandwidth, chirped in a quartz fiber, and then compressed with a grating pair to 1.5 ps. A second quartz fiber then provides nonlinear polarization rotation for background and satellite suppression and to further broaden the spectrum to 4.5 nm. Pulses are chirped again to 500 ps width with a second grating pair and amplified in a Ti:sapphire regenerative amplifier pumped by frequency-doubled Nd:YAG. Millijoule-level output is then amplified through the existing phosphate glass Trident amplifier chain before compression to < 400 fs. Energy up to 1.5 J with excellent beam quality and contrast ratio is routinely produced by compressing after three rod amplifier stages. Higher energies are possible by compression further along the amplifier chain. Simultaneous use of long (approximately 1 ns) pulses for plasma formation is also possible.
Educated Hope in an Age of Privatized Visions

Questions of agency and hope are inseparable from questions of politics and social struggle. As the vast majority of citizens become detached from public forums that nourish social critique, agency not only becomes a mockery of itself, it is replaced by market-based choices in which private satisfactions replace social responsibilities and biographic solutions become a substitute for systemic change. As the worldly space of criticism is undercut by the absence of public spheres that encourage the exchange of information, opinion, and criticism, the horizons of a substantive democracy disappear against the growing isolation and depoliticization that marks the loss of a politically guaranteed public realm in which autonomy, political participation, and engaged citizenship make their appearance. Drawing on the work of Cornelius Castoriadis, the author attempts to address the current crisis of meaning, political agency, and pedagogy and develop a cultural politics that links the notion of educated hope to the...
Gold‐Nanoparticle‐Enhanced Plasmonic Effects in a Responsive Polymer Gel

Localized surface plasmon resonance excited in gold nanoparticles coupled with a responsive polymer gel is explored. A specially designed structure (vertically aligned cylindrical pores decorated with gold nanoparticles) of responsive polymer gel thin films allows for the transduction of external signal/ stimuli into a strong optical effect enhanced by interactions of gold nanoparticles.
Genetic and Clinical Determinants Influencing Warfarin Dosing in Children With Heart Disease

Warfarin is a common anticoagulant with narrow therapeutic window and variable anticoagulation effects. Single gene polymorphisms in cytochrome P450 2C9 (CYP2C9) and vitamin K epoxide reductase (VKORC1) have been shown to impact warfarin dosing in adults. Insufficient data exists on genetic and clinical factors which influence warfarin dosing in children. Pediatric patients with heart disease who received long-term warfarin therapy were tested for VKORC1 and CYP2C9 polymorphisms. Clinical and demographic data were reviewed in those children who achieved stable therapeutic international normalized ratio (INR). Multiple linear regression modeling was used to assess relationships between stable warfarin doses and genetic or clinical variables. Fifty children were tested for VKORC1 and CYP2C9 polymorphisms; 37 patients (M 26: F 11) had complete data, achieved stable therapeutic INR, and were included in dose variability analysis. There were predominance of white race 73% and male sex 70.3%. The mean age was 9.6 years (1.8-18.6 years). The mean weight was 37.8 kg (7.7-95 kg). Fontan physiology and mechanical cardiac valves were two most common indications for chronic warfarin therapy (25/37 or 67.6%). Twelve patients (32.4%) had ≥ 2 indications for warfarin therapy. Three patients had documented venous or arterial clots, and 5 patients had strokes. Congenital heart disease was present in 29 patients (78.4%), including Fontan physiology (20), complex biventricular physiology (4), and congenital mitral valve disease (5). Acquired heart disease was present in 8 patients (21.6%), including Kawasaki disease with coronary aneurysms (3), acquired mitral valve disease (3), and Marfan syndrome (2). Stable warfarin dose (mg/kg/day) was strongly associated with VKORC1 polymorphism (p < 0.0001) and goal therapeutic INR (p = 0.009). Negative correlations were observed between stable warfarin dose and age, weight, height, and BSA (p = 0.04, 0.02, 0.02, and 0.02 respectively). Factors which did not influence warfarin dose included CYP2C9 polymorphism (p = 0.17), concurrent medications (p = 0.85), sex (p = 0.4), race (p = 0.14), congenital heart disease (p = 0.09), and Fontan physiology (p = 0.76). The gene-dose effect was observed in children with homozygous wild type VKORC1 CC, who required higher warfarin dose compared to those carrying heterozygous TC or homozygous TT (p = 0.028 and 0.0004 respectively). The full multiple linear regression model revealed that VKORC1 genotypes accounted for 47% of dosing variability; CYPC29 accounted for 5%. Overall, the combination of VKORC1, CYP2C9, age, and target INR accounted for 82% of dosing variability. In children with heart disease, VKORC1 genotypes, age, and target INR are important determinants influencing warfarin dosing in children with heart disease. Future warfarin dosing algorithm in children should factor both genetic and clinical factors.
Do Firms Increase Productivity in Order to Become Exporters

Recent studies find that exporters are more productive than non‐exporters and that entry into exporting does not increase firms’ productivity. Thus, firms self‐select into foreign markets. This paper examines productivity before entry into exporting. Using Chilean plant‐level data, we find that productivity and investment increase before plants begin to export. Moreover, productivity of entrants to exporting, but not that of non‐exporters and exporters, increases in response to increases in foreign income, before entry but not after that. The results suggest that the productivity advantage of future exporters may be the result of firms increasing their productivity in order to export.
A note on a modified primal‐dual algorithm to speed convergence in solving linear programs

The primal-dual algorithm is modified in a two part procedure. In the first part, the pivot row is selected so that an artificial variable is always dropped. The end of the first part usually produces some basic variables with negative values. The second part consists of selecting the most negative basic variable. The equation, represented by the selected basic variable, is multiplied through by minus one and then added to all equations with negative basic variables; it is then augmented by an artificial variable. This procedure produces feasibility for all basic variables and maintains canonical form. The standard primal-dual method is then used to complete the solution. Computational results are presented.
An airborne radar system for high-resolution mapping of internal layers

Accumulation rate is a key variable in assessing the mass balance of polar ice sheets. An improved knowledge of the mass balance of polar ice sheets is needed to determine their role in current and future sea level rise. Existing accumulation maps, derived from sparsely distributed ice cores and pits, contain accumulation rate errors as large as 20% in certain areas. Remote sensing methods to complement and supplement in situ measurements are required to generate improved accumulation maps. For this reason we have been investigating the use of high-resolution radars for mapping of near-surface internal layers and generating continuous profiles of the dated layers in the ice sheet (isochrones). We successfully mapped isochrones within 2 m of those in an ice core up to a depth of 280 m at the North GReenland Ice core Project (NGRIP) ice camp during the 1998 and 1999 field seasons using a 170-2,000 MHz frequency modulated continuous wave (FM-CW) radar. We described the system and reported results of our experiments in previous IGARSS meetings [Kanagaratnam et al. 1999, 2000]. Recently we performed detailed analysis of the data collected from these experiments and determined the frequency response of reflections from the internal layers. The results showed the optimum frequency range for monitoring near-surface layers is between 500 and 1000 MHz. Based on these results we are developing a 600-900 MHz coherent airborne radar for high-resolution mapping of the internal layers in the Greenland ice sheet. We designed this system to operate in different modes: simple pulse, chirped pulse, step-frequency, and FM-CW. We have also developed a digital data acquisition system to collect and process data. We designed this system such that it can operate in an undersampling mode to digitize the received signal directly without down conversion. In this paper we present results of data analysis and detailed design of the airborne radar.
The Periplasmic α-Carbonic Anhydrase Activity of Helicobacter pylori Is Essential for Acid Acclimation

ABSTRACT The role of the periplasmic α-carbonic anhydrase (α-CA) (HP1186) in acid acclimation of Helicobacter pylori was investigated. Urease and urea influx through UreI have been shown to be essential for gastric colonization and for acid survival in vitro. Intrabacterial urease generation of NH3 has a major role in regulation of periplasmic pH and inner membrane potential under acidic conditions, allowing adequate bioenergetics for survival and growth. Since α-CA catalyzes the conversion of CO2 to HCO3−, the role of CO2 in periplasmic buffering was studied using an α-CA deletion mutant and the CA inhibitor acetazolamide. Western analysis confirmed that α-CA was bound to the inner membrane. Immunoblots and PCR confirmed the absence of the enzyme and the gene in the α-CA knockout. In the mutant or in the presence of acetazolamide, there was an ∼3 log10 decrease in acid survival. In acid, absence of α-CA activity decreased membrane integrity, as observed using membrane-permeant and -impermeant fluorescent DNA dyes. The increase in membrane potential and cytoplasmic buffering following urea addition to wild-type organisms in acid was absent in the α-CA knockout mutant and in the presence of acetazolamide, although UreI and urease remained fully functional. At low pH, the elevation of cytoplasmic and periplasmic pH with urea was abolished in the absence of α-CA activity. Hence, buffering of the periplasm to a pH consistent with viability depends not only on NH3 efflux from the cytoplasm but also on the conversion of CO2, produced by urease, to HCO3− by the periplasmic α-CA.
Effect of Incentives and Aversiveness of Treatment on Willingness to Participate in Research

In three experiments, we studied the effect of incentives (0%, 1%, or 5% of grade points; $2 or $10) on willingness to participate in hypothetical experiments varying in degree of aversiveness. College students read a brief description of an experiment, rated their willingness to participate, and wrote comments. Willingness to participate was greater with larger incentives (in two of three experiments) and was lower for more aversive treatments (in all experiments). We discuss the teacher's role in the research process.
Comparison of growth physiology, morphology, and smolt indicators in juvenile Lake Superior brook trout (Salvelinus fontinalis) strains in reference to life history variation

Lake Superior supports fluvial, adfluvial, and lacustrine populations of brook trout (Salvelinus fontinalis). Adfluvial and lacustrine populations (termed coasters) are known for their large size a...
Single-molecule transition-state analysis of RNA folding

How RNA molecules fold into functional structures is a problem of great significance given the expanding list of essential cellular RNA enzymes and the increasing number of applications of RNA in biotechnology and medicine. A critical step toward solving the RNA folding problem is the characterization of the associated transition states. This is a challenging task in part because the rugged energy landscape of RNA often leads to the coexistence of multiple distinct structural transitions. Here, we exploit single-molecule fluorescence spectroscopy to follow in real time the equilibrium transitions between conformational states of a model RNA enzyme, the hairpin ribozyme. We clearly distinguish structural transitions between effectively noninterchanging sets of unfolded and folded states and characterize key factors defining the transition state of an elementary folding reaction where the hairpin ribozyme's two helical domains dock to make several tertiary contacts. Our single-molecule experiments in conjunction with site-specific mutations and metal ion titrations show that the two RNA domains are in a contact or close-to-contact configuration in the transition state even though the native tertiary contacts are at most partially formed. Such a compact transition state without well formed tertiary contacts may be a general property of elementary RNA folding reactions.
Wavepacket diagnosis with chirped probe pulses

For linearly chirped probe pulses, the observable pump-probe signal can be obtained analytically under useful idealizations: Gaussian packet and pulse, linear chirp, linear difference potential, and constant wavepacket group velocity within the probe window. These conditions allow the expression of the signal as a cross correlation between packet and probe window traveling in coordinate space at velocities ˝ and ˝ , respectively. The signal delay and its integrated area are l independent of chirp. Relative to zero-chirp, the signal is temporally compressed for 0 -˝r˝ - 2, and becomes a minimum l when packet and window co-propagate, ˝ s˝ . Experimental data are used to illustrate wavepacket diagnosis in a real l
Commentary: The birth of the twin study—a commentary on Francis Galton’s ‘The History of Twins’

In this passage, the primary stirp is the stirp of a zygote immediately after it has been fertilized and the secondary stirps of monozygotic twins are their stirps immediately after the zygote has divided into two. Galton explains the similarities of three classes of twins as follows. (i) Monozygotic twins who divided shortly after conception are very similar because they have very similar secondary stirps derived from the division of the same primary stirp, and these secondary stirps develop in very similar conditions. (ii) Dizygotic twins and siblings are moderately similar because they are derived from very similar primary stirps, which develop under somewhat similar conditions. No prediction is made about the degree of similarity. (iii) Monozygotic twins who divided a considerable time after conception are very dissimilar because the primary stirp, which divides into two, has been organized into contrasting halves. Galton could not in 1875 have invented the classical twin method based on this non-Mendelian theory of heredity. What he did was to track the life-history changes of twins to see whether twins who were very similar at birth diverged in later life or whether twins who were very dissimilar at birth converged later, as a test of the relative importance of nature and nurture. The classical twin method of comparing the similarities of monozygotic and dizygotic twins on Mendelian assumptions was first used in the 1920s.
Coxiella burnetii: Host and bacterial responses to infection

Designation as a Category B biothreat agent has propelled Coxiella burnetii from a relatively obscure, underappreciated, "niche" microorganism on the periphery of bacteriology, to one of possibly great consequence if actually used in acts of bioterrorism. Advances in the study of this microorganism proceeded slowly, primarily because of the difficulty in studying this obligate intracellular pathogen that must be manipulated under biosafety level-3 conditions. The dogged determination of past and current C. burnetii researchers and the application of modern immunological and molecular techniques have more clearly defined the host and bacterial response to infection. This review is intended to provide a basic introduction to C. burnetii and Q fever, while emphasizing immunomodulatory properties, both positive and negative, of Q fever vaccines and C. burnetii infections.
Analysis of trapping effects in AlGaN/GaN HEMTs based on near zero bias output conductance

A simple model is developed for characterization of current collapse caused by electron trapping in AlGaN/GaN HEMTs. Threshold voltages are extracted from near-zero drain bias output conductance characteristics with respect to gate bias based on 0.2 μs pulsed I –V characteristics at different quiescent bias points. Other device parameters such as effective gate length and electron mobility are also estimated by fitting to a model equation. The results show that a higher negative electric field between gate and drain contacts cause a higher threshold voltage shift in the positive direction and a longer effective gate length, resulting in a larger current dispersion due to trapping of more electrons. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
Do Gravity Waves Transport Angular Momentum Away From Tropical Cyclones

Abstract Previous studies have suggested that gravity waves can transport a significantly large amount of angular momentum away from tropical cyclones, as much as 10% of the core angular momentum per hour. These previous studies used the shallow-water equations to model gravity waves radiating outward from rapidly rotating inner-core asymmetries. This issue is reinvestigated with a three-dimensional, nonhydrostatic, linear model of the vortex-anelastic equations. The response of balanced, axisymmetric vortices modeled after tropical cyclones to rotating asymmetric heat sources is examined to assess angular momentum transport by gravity waves radiating away from the core region of the vortices. Calculations show that gravity waves do transport angular momentum away from the vortex core; however, the amount transported is several orders of magnitude smaller than recent estimates.
Quantum mechanical prediction of four-phonon scattering rates and reduced thermal conductivity of solids

Recently, first principle-based predictions of lattice thermal conductivity $\ensuremath{\kappa}$ from perturbation theory have achieved significant success. However, it only includes three-phonon scattering due to the assumption that four-phonon and higher-order processes are generally unimportant. Also, directly evaluating the scattering rates of four-phonon and higher-order processes has been a long-standing challenge. In this work, however, we have developed a formalism to explicitly determine quantum mechanical scattering probability matrices for four-phonon scattering in the full Brillouin zone, and by mitigating the computational challenge we have directly calculated four-phonon scattering rates. We find that four-phonon scattering rates are comparable to three-phonon scattering rates at medium and high temperatures, and they increase quadratically with temperature. As a consequence, $\ensuremath{\kappa}$ of Lennard-Jones argon is reduced by more than 60% at 80 K when four-phonon scattering is included. Also, in less anharmonic materials---diamond, silicon, and germanium---$\ensuremath{\kappa}$ is still reduced considerably at high temperature by four-phonon scattering by using the classical Tersoff potentials. Also, the thermal conductivity of optical phonons is dominated by the fourth- and higher-orders phonon scattering even at low temperature.
The Global Emergence of a Field: Content, Form, and Promise in Women’s Studies

One of the strongest examples of the influence of the external environment upon the university is evident in the emergence of women’s studies programs. Triggered by the women’s movement in the 1970s, academics—mostly women, and mostly feminists among them—developed related research and teaching activities in their respective institutions (Nayar, 1996; Bonder, 1997). Their contributions helped systematize many of the experiences in the movement and were decisive in the production of concepts and theories to explain the logic and objectives of the women’s movement and set the basis for a new field of study centered on the role of socially constructed similarities and differences of human beings.
Transforaminal Lumbar Interbody Fusion: Prognostic Factors Related to Retention in an Active Duty Military Population

ABSTRACTLittle information is available regarding patient-based factors that may influence results following transforaminal lumbar interbody fusion (TLIF) in younger, high-demand individuals. A query of all TLIF procedures performed on active duty military personnel at our institution was conducted for the time period 2005 to 2008. Data was abstracted, including age, gender, military rank, preoperative diagnosis, complications, and ability to remain in the military. Favorable outcome was defined as the ability of the patient receiving TLIF to remain on active duty, without medical separation (Medical Evaluation Board [MEB]), at a minimum of 1 year postsurgery. Univariate analysis was conducted to identify potential risk factors for MEB. Factors with a univariate p value <0.2 were included in multivariate analysis and sensitivity testing to identify independent predictors of outcome. The cohort included 143 patients with an average age of 36.3 years and mean follow-up of 34.9 months. Younger age (odds rati...