cssi/SciSciGPT-SciSciNet huggingface dataset:
Single Molecule FRET Studies of RNA Tertiary Folding: Elucidating the Thermodynamic and Kinetic Role of Na+ Cations

Understanding the kinetics and thermodynamics of the stabilizing interactions in non-coding RNA provides crucial information about their structural dynamics and ultimately, their biological function. The use of single-molecule FRET methods allows us to investigate the real-time folding and unfolding of an isolated GAAA tetraloop-receptor interaction in the Tetrahymena ribozyme. Cation-dependent folding studies of this ubiquitous interaction show that increasing concentrations of Na+ significantly increase the rate constant for docking and slightly decrease the rate constant for undocking. We examine the temperature-dependence of this Na+-induced folding in order to determine the thermodynamic parameters associated with the folding and unfolding processes. At 150 mM Na+ the folding process is exothermic (ΔH° = −20 kcal/mol) but with a significant entropic cost (ΔS° = −67 cal/mol K), leading to a near zero ΔG° at 298 K. Increasing concentrations of Na+ dramatically increase both ΔH° and ΔS°, with the competition yielding a decrease in ΔG°. For example, by 600 mM Na+ the folding process even becomes endothermic (ΔH° = 4.3 kcal/mol) and entropically rewarding (ΔS° = 20 cal/mol K), with the folding process now becoming slightly favorable (ΔG° = −1.7 kcal/mol). These results indicate that increasing Na+ concentration favors folding by increasing entropic gains more than enthalpic losses, which leads to a more favorable folding free energy change. We propose a model that uses the competing roles of solvent and structure to explain these gains and losses.
An analysis of visual-graphic symbol meanings for two nonspeaking adults with severe mental retardation

In the language acquisition literature, the child's use of a word for a referent (or referents) has provided information about the nonlinguistic meaning of that word for him or her. With the increased use of augmentative and alternative communication (AAC) systems for persons with mental retardation, examination of the meanings symbols have for an individual can provide insights into the ways in which symbols are learned. As well, such analyses can serve as an indicator of the underlying conceptual knowledge the individuals have for the symbol meanings they are being taught. This preliminary report describes a post hoc analysis of the ways in which 2 young adults with severe retardation extended the meanings of visual-graphic symbols in an instructional setting. Two types of extensions were observed and subsequently characterized. Clinical and research implications are provided.
Sleep Disturbances and Correlates of Children with Autism Spectrum Disorders

This study examined sleep patterns, sleep problems, and their correlates in children with autism spectrum disorders (ASD). Subjects consisted of 167 ASD children, including 108 with autistic disorder, 27 with Asperger's syndrome, and 32 with other diagnoses of ASD. Mean age was 8.8 years (SD = 4.2), 86% were boys. Parents completed a self-administered child sleep questionnaire. Results showed that average night sleep duration was 8.9 h (SD = 1.8), 16% of children shared a bed with parent. About 86% of children had at least one sleep problem almost every day, including 54% with bedtime resistance, 56% with insomnia, 53% with parasomnias, 25% with sleep disordered breathing, 45% with morning rise problems, and 31% with daytime sleepiness. Multivariate logistic regression analyses indicated that younger age, hypersensitivity, co-sleeping, epilepsy, attention-deficit/hyperactivity disorder (ADHD), asthma, bedtime ritual, medication use, and family history of sleep problems were related to sleep problems. Comorbid epilepsy, insomnia, and parasomnias were associated with increased risk for daytime sleepiness. Results suggest that both dyssomnias and parasomnias are very prevalent in children with ASD. Although multiple child and family factors are associated with sleep problems, other comorbid disorders of autism may play a major role.
Reversal theory analysis of relapse crises following smoking cessation

Abstract Smoking continues to be a habit that is extremely difficult to change despite increasing social pressure to do so. Models that look for consistency within individuals do not adequately account for the high rate of relapse following smoking cessation. Reversal theory provides an excellent framework for understanding the situations in which ex-smokers are at greatest risk of smoking. This paper discusses the application of reversal theory to research on smoking cessation and relapse. A two-phase study using interview data was conducted to test the relationship between reversal theory constructs and smoking outcome. Interviews were obtained from 3 to 15 months after cessation in phase 1 and from 2 to 26 weeks after cessation in phase 2. In phase 1, ex-smokers were significantly more likely to smoke when tempted while in either paratelic or negativistic states. In phase 2, ex-smokers were significantly more likely to smoke when tempted while in either paratelic or mastery states. These results suggest that future smoking cessation programs should incorporate state-specific interventions to deal with temptations to smoke.
Response of Herbicide-Resistant Palmer Amaranth (Amaranthus palmeri) Accessions to Drought Stress

Palmer amaranth is a very problematic weed in several crops in the southern USA due to its competitive ability and resistance to herbicides representing different mechanisms of action. Variation in growth and subsequent interference of North Carolina Palmer amaranth accessions has not been examined. A greenhouse experiment determined response of 15 North Carolina Palmer amaranth accessions to drought stress beginning 15 days after seedling emergence (DAE) for a duration of 3, 5, 7, and 9 days. Following exposure to drought, plants were grown under optimal moisture conditions until harvest at 30 DAE. Five accessions each of glyphosate-resistant (GR), acetolactate synthase inhibitor-resistant (ALSR), and acetolactate synthase inhibitor-susceptible and glyphosate-susceptible (ALSS/GS) were compared. Variation in response to drought stress, based on height and dry weight reduction relative to nonstressed controls, was noted among accessions. Stress for 3 or more days affected height and dry weight. Height and dry weight of GR and ALSR accession groups were reduced less by drought than the ALSS/GS accession group. Results suggest a possible relationship between herbicide resistance and ability of Palmer amaranth to withstand drought stress and thus a possible competitive advantage for resistant accessions under limited moisture availability.
Current pharmacological treatments for nicotine dependence

Abstract There are nearly 1.1 billion users of nicotine and tobacco products worldwide. Tobacco use through cigarette smoking is the leading preventable cause of death in the world and kills nearly four million people annually. However, although some cigarette smokers are able to quit, many are not, and standard medications to assist in smoking cessation (e.g. nicotine-replacement therapies and sustained-release bupropion) are ineffective in many remaining smokers. Recent developments in our understanding of the neurobiology of nicotine dependence have identified several neurotransmitter systems that might contribute to the process of smoking maintenance and relapse, including dopamine, noradrenaline, 5-hydroxytryptamine, acetylcholine, endogenous opioids, GABA, glutamate and endocannabinoids. Several existing medications are being tested as treatments for nicotine dependence and novel investigational agents are under development as effective treatments for nicotine dependence in the ‘hard to treat' tobacco user.
Relationship between Plasma Iohexol Clearance and Urinary Exogenous Creatinine Clearance in Dogs

The objective of this study was to determine if plasma iohexol clearance, computed by a 1-compartment model defined by 3 plasma samples, was an accurate measure of glomerular filtration rate (GFR) in dogs. Twenty-two adult Beagle dogs of both genders were studied. Ten dogs had intact kidneys, and 12 dogs had surgically reduced renal mass. A bolus injection of iohexol was made, and blood was obtained for plasma iohexol assay after 120, 180, and 240 minutes. Plasma was analyzed for iohexol concentration by means of 3 assay methods: chemical, high-performance liquid chromatography (HPLC), and inductively coupled plasma emission spectroscopy (ICP). Urinary clearance of exogenous creatinine was used to measure GFR for three 30-minute periods occurring between 150 and 240 minutes after iohexol injection. Plasma clearance of iohexol and renal clearance of creatinine were compared by linear regression analysis and by limits of agreement techniques. Plasma iohexol clearance and urinary exogenous creatinine clearance were significantly correlated (chemical R2= .90; HPLC R2= .96; and ICP R2= .96). The 1-compartment iohexol clearance: exogenous creatinine clearance ratios were 1.04 ± 0.17, 1.05 ± 0.14, and 1.10 ± 0.15 for the chemical, HPLC, and ICP methods of assay, respectively, indicating that plasma iohexol clearance slightly overestimated GFR. Assuming a ±2 standard deviation interval for error, corrected plasma iohexol clearance measured GFR with ±34% accuracy for the chemical, ±26% accuracy for the HPLC, and ±27% accuracy for the ICP method. These results indicate that plasma iohexol clearance should have utility for detection of renal dysfunction earlier in the course of progressive renal disease than is possible with measurement of plasma creatinine or urea concentrations.
Decreased withdrawal symptoms but normal tolerance to nicotine in mice null for the α7 nicotinic acetylcholine receptor subunit

Abstract Withdrawal symptoms are a major deterrent when people try to quit smoking. The α7 subunit of the neuronal nicotinic acetylcholine receptor (nAChR) is highly expressed in the brain, and has been suspected to play a major role in nicotine addiction. We studied the influence of α7-containing nAChRs on nicotine withdrawal and tolerance, in wild type mice and mice null for the α7 nAChR subunit (α7 −/−). For withdrawal experiments, animals were implanted with osmotic minipumps delivering nicotine for 13 days. A single intraperitoneal injection of the nAChR antagonists mecamylamine (MEC) or methyllycaconitine (MLA) was used to precipitate withdrawal. In wild type mice, both MEC- and MLA-precipitated somatic signs of withdrawal such as increased grooming, scratching and shaking. In α7 −/− mice, the somatic effects of MEC-precipitated nicotine withdrawal were significantly reduced. Interestingly, the presumed α7-specific antagonist MLA also precipitated withdrawal. Tolerance, which was measured as a decrease in nicotine-induced hypolocomotion after subchronic nicotine treatment, was normal in α7 −/− mice. Finally, because anxiety and withdrawal symptoms are highly correlated in humans, we studied anxiety-like behaviors in α7 −/− mice using a battery of anxiety-related tests. The behavior of α7 −/− mice was indistinguishable from that of control mice. Our results point to the α7 subunit as one of the players in nicotine withdrawal, but not in nicotine tolerance or basal anxiety-like behavior.
On the influence of second phase precipitation on ion implantation profiles

Abstract We present here a numerical model for the calculation of ion implantation profiles that can account for the effect of second phase precipitation occurring during the implantation process. The model is based on the numerical solution of the transport equations including the processes of ion collection, sputtering, diffusion, and second phase precipitation. The model uses a maximum concentration of the implanted species that can be tolerated in solution and beyond this concentration the incoming ions are assumed to form a precipitated phase. The model predicts the total implantation profile plus the fraction of the implanted species that is precipitated as a function of depth. Calculations are presented for the case of nitrogen implantation into niobium targets.
On reliability calculations when stresses are generated by a non-homogeneous poisson process

Abstract Reliability of a structure with random strength is investigated assuming that the occurrences of random stresses are governed by a non-homogeneous Poisson process. Here calculations are carried out based on the observation that the failure corresponds to the occurence of the first record stress (new high in the sequence of stresses) relative to the random strength of the component. Explicit formulae for two practically important cases are derived and two examples using real data for wind and earthquake are included.
Folding Mechanism Of The Z Mutant Of Human Antitrypsin Studied By H/D Exchange

The serpins are a unique family of serine protease inhibitors which possess an inherent ability to fold to their active metastable state and avoid thermodynamically more stable conformation. This metastability is crucial for their biological function as they undergo large conformational changes to the stable relaxed (R) state during protease inhibition. Though dramatic conformational mobility of serpins is required for their activity, this also renders them vulnerable to misfolding and polymerization. Misfolding and polymerization are observed in some genetic variants of plasma serpins such as antitrypsin, antichymotrysin and antithrombin III leading to a diverse range of diseases including cirrhosis, dementia, thrombosis, angioadema and emphysema. Studies on the Z variant of human α1 antitrypsin (α1-AT) suggested that extremely retarded folding traps the molecule in an intermediate conformation which has a high tendency to form polymeric aggregates. However, there is no specific report on the nature of the folding intermediate. In the present study we have tried to follow the refolding pathway of the Z variant of α1-AT by hydrogen/deuterium exchange mass spectrometry. Hydrogen/ deuterium exchange mass spectrometry is a powerful method in analyzing the folding/ unfolding of a protein in a region specific manner. We observed different refolding kinetics for different parts of the protein. For most of the regions only 25-30% refolding was observed even after 20 hours. Maximum refolding of 60% was observed for residues 120-142 containing helix E. These studies will shed new light on the nature of the polymerization prone folding intermediate of the Z variant.
Synthesis, 9Be NMR Spectroscopy, and Structural Characterization of Sterically Encumbered Beryllium Compounds

The use of the terphenyl substituent −C6H3-2,6-Mes2 (abbreviated Ar) has permitted the synthesis of several new low-coordinate beryllium compounds. Reaction of 1 equiv of LiAr with BeCl2(OEt2)2 or ...
Sonication-laser-excited time-resolved Shpol'skii spectrometry: a facile method for the direct screening of fifteen priority pollutants in soil samples.

A unique method for screening polycyclic aromatic hydrocarbons (PAH) in soil samples is reported. Milligrams of soil are sonicated into the vial of a cryogenic fiber-optic probe with 250 μL of n-octane. Pollutants partition into the layer of extracting solvent and the cryogenic probe is then used for fluorescence measurements at liquid helium temperature (4.2 K). N-octane provides PAH with the appropriate Shpol'skii matrix to record highly resolved spectra and characteristic fluorescence lifetimes. Unambiguous PAH determination is directly performed from the layer of extracting solvent with no need for previous PAH separation. The total analysis time from the extraction to PAH identification is approximately 35 min per sample. Limits of detection are at the sub-parts per billion levels. PAH recoveries are similar to those obtained via high-performance liquid chromatography analysis. The simplicity of the experimental procedure, the short analysis time, the selectivity, and the excellent analytical figures of merit demonstrate the advantages of this approach for routine analysis of soil samples.
Inhibition of macrophage secretion by tetanus toxin is not directly linked to cytosolic calcium homeostasis.

Abstract Tetanus toxin (TT) inhibits secretion of neurotransmitters from neurons and lysozyme from human macrophages (MO). Because these secretory events are associated with changes in cytosolic free calcium [Ca 2+ ] i , we examined the effect of TT on MO calcium homeostasis and secretion in response to ionomycin and phorbol myristate acetate (PMA). Using Quin 2 to report [Ca 2+ ] i , basal [Ca 2+ ] i was similar for control cells (133 nM) and MO treated with TT (127 nM). In response to ionomycin (50 nM) [Ca 2+ ] i increased to 548 + 74 nM in control cells and to 357 + 36 nM in TT-treated MO (p − = 12). Despite this rise in [Ca 2+ ] i , neither control MOs nor TT-treated MOs secreted the lysosomal enzyme lysozyme in response to this concentration of ionomycin (50 nM). In both control and TT-treated MO, stimulation with a higher concentration of ionomycin (1000 nM) caused saturation of the quin 2 fluorescence signal. However, lysozyme secretion from TT-MO was inhibited. In response to the phorbol ester, PMA (3 uM), [Ca 2+ ] i did not increase in either control MO or TT-treated MO. However, secretion of lysozyme from TT-treated MO was also inhibited in response to this stimulus (70.8% of control, p
2,3‐Diiodo‐1‐(phenyl­sulfon­yl)‐1H‐indole

In the title compound, C14H9I2NO2S, the two I atoms lie essentially in the plane of the indole ring and there is some iodine–iodine repulsion.
The effect of type of redundancy on retention in preschool children

The effect of verbal and nonverbal redundancy on the retention of 30 4-year-old children was examined to determine if the type of redundancy, as opposed to redundancy perse, facilitated the retention of this age child. The results demonstrated that the representational abilities of the child determine what type of redundant information will aid retention.
The question of thresholds for carcinogenesis.

AbstractThe principle of tolerance to injurious substances and the use of threshold limit values have been central to the practice of occupational health. The concept of a threshold is well established in biological processes, for example, synaptic transmission and nerve stimulation as well as for acute effects of chemicals and radiation. Obviously, the protection of both the worker and general population would be greatly simplified if thresholds for carcinogenesis also existed and could be determined. Unfortunately, thresholds for carcinogenesis are like leprechauns, it is difficult to demonstrate their existence, but they generate lively if not always completely rational discussions.
Pain intensity assessment by bedside nurses and palliative care consultants: a retrospective study

To evaluate the specificity, sensitivity, and accuracy of pain intensity assessments (0–10) conducted by registered nurses (RN) and clinical nurse assistants (CAN) as compared to those conducted by the palliative care consultant (PCC). We performed a retrospective review of charts of patients who had received palliative care consult between April 2002 and August 2002. Data on patient demographic, date of palliative care consult, and date and intensity of pain assessment were collected. A numerical rating scale from 0 (no pain) to 10 (worst pain) was used to assess pain intensity. The data were included for analysis if the pain intensity assessment was performed during the same shift by all three care providers (RN, CNA, and PCC). Forty-one charts were found to include a complete pain assessment performed by the RN, CNA, and PCC. The agreement of pain intensity between the PCC and both the RN and CNA was poor. For a diagnosis of moderate-to-severe pain, the RN’s intensity assessment had a specificity of 90% but a sensitivity of 45%, and the CNA’s intensity assessment had a specificity of 100% but a sensitivity of only 30%. The Spearman correlation coefficient between the intensity assessments performed by the PCC and the RN was 0.56 (p=0.00) and between those by the PCC and the CNA 0.22 (p=0.15). Lack of agreement between pain intensity assessments performed by the PCC and bedside nurse suggests possible inconsistencies in the way the assessments were performed. Better education on how to perform standard pain intensity assessment is needed.
Percolation in short-fiber composites: Cluster statistics and critical exponents

The influence of microstructure on the percolation process in short-fiber composites has been examined in terms of the cluster statistics measured in a 3D continuum system. Simulation results are presented for a distributed fiber length system, in contrast to the results reported in the literature for uniform fiber lengths. The critical percolation exponents for the 3D continuum short-fiber composite system were found to compare well with those of 2D and 3D lattice systems reported in the literature. A fractal dimension of 2.3 was calculated from the above critical exponents as well as from the growth of the radius of gyration of the fibrous clusters. As expected, the fractal dimension increased as the fiber orientation in the clusters changed from a preferentially aligned one (as observed in injection-molded composites) to a more random microstructure (as observed in compression-molded composites).
Ideal current patterns yielding optimal signal‐to‐noise ratio and specific absorption rate in magnetic resonance imaging: Computational methods and physical insights

At high and ultra-high magnetic field strengths, understanding interactions between tissues and the electromagnetic fields generated by radiofrequency (RF) coils becomes crucial for safe and effective coil design, as well as for insight into limits of performance. In this work we present a rigorous electrodynamic modeling framework, using dyadic Green’s functions, to derive the electromagnetic field in homogeneous spherical and cylindrical samples resulting from arbitrary surface currents in the presence or absence of a surrounding RF shield. We show how to calculate ideal current patterns which result in the highest possible signal to noise ratio (“ultimate intrinsic signal to noise ratio (SNR)”) or the lowest possible RF power deposition (“ultimate intrinsic specific absorption rate (SAR)”) compatible with electrodynamic principles. We identify familiar coil designs within optimal current patterns at low to moderate field strength, thereby establishing and explaining graphically the near-optimality of traditional surface and volume quadrature designs. We also document the emergence of less familiar patterns, e.g. involving substantial electric as well as magnetic dipole contributions, at high field strength. Performance comparisons with particular coil array configurations demonstrate that optimal performance may be approached with finite arrays if ideal current patterns are used as a guide for coil design.
An Essential GTPase Promotes Assembly of Preribosomal RNA Processing Complexes

Ribosome biogenesis in eukaryotes is a highly regulated process involving hundreds of transiently associated proteins and RNAs. Although most of these assembly factors have been genetically linked to specific step(s) in the biogenesis pathway, their biochemical functions are generally unknown. Bms1, an essential protein in yeast, is the only known GTPase required for biosynthesis of the 40S ribosomal subunit and interacts with Rcl1, an essential protein suggested to be an endonuclease. Here, we show thermodynamic coupling in the binding of Bms1 to GTP, Rcl1, and U3 small nucleolar RNA (snoRNA), an essential RNA that base pairs to pre-rRNA. Rcl1 binding to preribosomes is severely limited in yeast cells expressing a Bms1 mutant defective for Rcl1 binding. Additionally, we provide evidence that the C-terminal domain of Bms1 acts as an intramolecular GTPase-activating protein. Together, these data suggest that Bms1 functions as a GTP-regulated switch to deliver Rcl1 to preribosomes, providing molecular insight into preribosome assembly.
On the determination of the roots of some classes of transcendental equations

A new approach is developed for fast, automatic and accurate computation of the roots of some classes of transcendental equations without the risk of missing any one of the roots. The method permits the calculation of as many eigenvalues as desired or any one of them directly, without the need for computing the previous ones. The computation procedure is based on the count of the number of roots of the transcendental equation lying between zero and some prescribed value in the eigenvalue spectrum. Basic rules in the application of this method are described, and its use for determining the roots of the transcendental equation is illustrated with examples.
Accuracy of teledermatology for pigmented neoplasms

Background Studies of teledermatology utilizing the standard reference of histopathology are lacking. Objective To compare accuracy of store-and-forward teledermatology for non-pigmented neoplasms with in-person dermatology. Methods This study was a repeated-measures equivalence trial involving veterans with non-pigmented skin neoplasms. Each lesion was evaluated by an in-person dermatologist and a teledermatologist; both generated a primary diagnosis, up to two differential diagnoses, and management plan. The primary outcome was aggregated diagnostic accuracy (percent correct matches of any chosen diagnosis with histopathology). Secondary outcomes included management plan accuracy (percent correct matches with expert panel management plan). Additional analyses included evaluation of the incremental effect of using polarized light dermatoscopy in addition to standard macro images, and evaluating benign and malignant lesion subgroups separately. Results Most of the 728 participants were male (97.8%) and Caucasian (98.9%). The aggregated diagnostic accuracy (primary outcome) of teledermatology (macro images) was not equivalent (95% confidence interval [CI] for difference within +/−10%) and was inferior (95% CI lower bound P = .0017). The addition of polarized light dermatoscopy showed the same pattern for malignant lesions, but not for benign lesions. Most interestingly, for malignant lesions, the addition of polarized light dermatoscopy yielded equivalent aggregated diagnostic accuracy rates. Limitations Non-diverse study population. Conclusions Using macro images, the diagnostic accuracy of teledermatology was inferior to in-person dermatology, but accuracy of management plans was equivalent. The addition of polarized light dermatoscopy yielded significantly better aggregated diagnostic accuracy, but management plan accuracy was not significantly improved. For the important subgroup of malignant lesions, the addition of polarized light dermatoscopy yielded equivalent diagnostic accuracy between teledermatologists and clinic dermatologists.
The Wrong Man is President! Overvotes in the 2000 Presidential Election in Florida

Using ballot-level data from the NORC Florida ballots project and ballot-image files, I argue that overvoted ballots in the 2000 presidential election in Florida included more than 50,000 votes that were intended to go to either Bush or Gore but instead were discarded. This was primarily due to defective election administration in the state, especially the failure to use a system to warn each voter when too many marks were on a ballot and allow the voter to make corrections. If the best type of vote tabulation system used in Florida in 2000—precinct-tabulated optical scan ballots—had been used everywhere in the state, Gore would have won by more than 30,000 votes. Florida's election experience points to the need to gather ballot-level data to evaluate the success of election reform efforts now underway in much of the United States.Walter R. Mebane Jr. has published numerous articles concerning topics in American politics, especially elections, and political methodology. An early version of this work was presented at a seminar at the University of Minnesota in April 2003. The author thanks Jason Conn, Anthony Keeney, and Mike Rosenberg for assistance, and Jasjeet Sekhon for helpful discussion.
Different Conformations of the Kinase-On and Kinase-Off Signaling States in the Aer HAMP Domain

HAMP domains are sensory transduction modules that connect input and output domains in diverse signaling proteins from archaea, bacteria, and lower eukaryotes. Here, we employed in vivo disulfide cross-linking to explore the structure of the HAMP domain in the Escherichia coli aerotaxis receptor Aer. Using an Aer HAMP model based on the structure of Archaeoglobus fulgidus Af1503-HAMP, the closest residue pairs at the interface of the HAMP AS-1 and AS-2′ helices were determined and then replaced with cysteines and cross-linked in vivo. Except for a unique discontinuity in AS-2, the data suggest that the Aer HAMP domain forms a parallel four-helix bundle that is similar to the structure of Af1503. The HAMP discontinuity was associated with a segment of AS-2 that was recently shown to interact with the Aer-PAS sensing domain. The four-helix HAMP bundle and its discontinuity were maintained in both the kinase-on and kinase-off states of Aer, although differences in the rates of disulfide formation also indicated the existence of different HAMP conformations in the kinase-on and kinase-off states. In particular, the kinase-on state was accompanied by significantly increased disulfide formation rates at the distal end of the HAMP four-helix bundle. This indicates that HAMP signaling may be associated with a tilting of the AS-1 and AS-2′ helices, which may be the signal that is transmitted to the kinase control region of Aer.
RADIATION-TOLERANT DESIGN FOR HIGH PERFORMANCE MIXED-SIGNAL CIRCUITS

Modern semiconductor processes can provide significant intrinsic hardness against radiation effects in digital and analog circuits. Current design techniques using commercial processes for radiation-tolerant integrated circuits are summarized, with an emphasis on their application in high performance mixed-signal circuits and systems. Examples of "radiation hardened by design" (RHBD) methodologies are illustrated for reducing the vulnerability of circuits and components to total dose, single-event, and dose-rate effects.
Medium PRF set selection: an approach through combinatorics

Modern fighter aircraft use a host of different techniques to search for and detect airborne targets. One such technique involves the use of pulse Doppler and a collection of 'medium' pulse repetition frequencies (PRFs). Such a collection of medium PRFs is ambiguous in both range and velocity (Doppler frequency), but can be resolved by correlating data from different members of the set. The PRF set selection is complex, restricted by the particular radar system and its intended use. After briefly discussing constraints, some results concerning ghost minimisation, and the linearity of clear region probabilities, an efficient method is presented for calculating PRF set quality. A discussion of the mathematical (in particular combinatorial) niceties which attend the solution of this problem is included.
Associations of Self-Reported Cigarette Smoking with Chronic Obstructive Pulmonary Disease and Co-Morbid Chronic Conditions in the United States

AbstractBackground: The question of how smoking, COPD, and other chronic diseases are related remains unresolved. Therefore, we examined relationships between smoking, COPD, and 10 other chronic diseases and assessed the prevalence of co-morbid chronic conditions among people with COPD.Methods: We analyzed cross-sectional data from 405,856 US adults aged 18 years or older in the 2011 Behavioral Risk Factor Surveillance System. We used log-linear regression to estimate prevalence ratios (PRs) and their corresponding 95% confidence intervals (CIs) for these relationships adjusting for age, gender, race/ethnicity, marital status, educational attainment, annual household income, and health insurance coverage.Results: Overall, 17.5% reported being current cigarette smokers, 6.9% reported having COPD, and 71.2% reported another chronic condition. After age-adjustment, prevalence of COPD was 14.1% (adjusted PR = 3.9; 95% CI: 3.7, 4.1) among current smokers and 7.1% (adjusted PR = 2.5; 95% CI: 2.4, 2.7) among for...
The Validity of Dynamical Models of the Solar Atmosphere

Important results on the structure and dynamics of the nonmagnetic solar chromosphere are based on hydrodynamic models that oversimplify either the geometry of the atmosphere or the interaction of radiation and matter. Although the observed granulation pattern is well reproduced by the three-dimensional (3D) models, oversimplification of radiative relaxation leads to the prediction of temperature fluctuations that are too high (by a factor of 10 to 100) and result in a monotonic decrease with height in the chromosphere of the horizontally and temporally averaged temperature, and hence in the prediction of absorption lines at wavelengths where only emission lines are observed on the Sun. New values of solar abundances of oxygen and other metals are based on 3D hydrodynamic models with temporal and spatial fluctuations that are far greater than those observed. These new abundances destroy the previous agreement of observed modes with acoustic eigenmodes that had been predicted for the old abundances from a solar model for which the sound speed throughout most of the Sun was determined to an accuracy of a few parts in 104. One expects that, when radiative relaxation is properly accounted for, 3D models will reproduce the essential characteristics of the solar atmosphere, among them a positive temperature gradient in the outward direction and hence exclusively emission lines in the extreme ultraviolet at all times and positions in the nonmagnetic chromosphere. A minimum characteristic length of 0.1 arcsec is identified for the solar atmosphere, below which there is no significant structure in the actual Sun, only in wave models of the Sun. This criticism does not detract from the notable success of hydrodynamic modeling to explain the mechanism by which chromospheric H2V and K2V bright points are formed.
Cluster analysis for DNA methylation profiles having a detection threshold

DNA methylation, a molecular feature used to investigate tumor heterogeneity, can be measured on many genomic regions using the MethyLight technology. Due to the combination of the underlying biology of DNA methylation and the MethyLight technology, the measurements, while being generated on a continuous scale, have a large number of 0 values. This suggests that conventional clustering methodology may not perform well on this data. We compare performance of existing methodology (such as k-means) with two novel methods that explicitly allow for the preponderance of values at 0. We also consider how the ability to successfully cluster such data depends upon the number of informative genes for which methylation is measured and the correlation structure of the methylation values for those genes. We show that when data is collected for a sufficient number of genes, our models do improve clustering performance compared to methods, such as k-means, that do not explicitly respect the supposed biological realities of the situation. The performance of analysis methods depends upon how well the assumptions of those methods reflect the properties of the data being analyzed. Differing technologies will lead to data with differing properties, and should therefore be analyzed differently. Consequently, it is prudent to give thought to what the properties of the data are likely to be, and which analysis method might therefore be likely to best capture those properties.
Neutrophils, Nitric Oxide, and Microvascular Permeability in Severe Sepsis

Study objectives Alterations in microvascular permeability are prevalent in patients with sepsis; a recent study reported that patients with septic shock had increased capillary filtration coefficient (Kf), a noninvasive index of microvascular permeability. We aimed to determine whether patients with severe sepsis had increased Kf, and whether the magnitude of Kf correlated with indexes of nitric oxide activity and neutrophil activation. Design Single-center, prospective study. Setting Twenty-five–bed ICU of a medical college-affiliated teaching hospital. Patients Fifteen ICU patients with severe sepsis based on the American College of Chest Physicians/Society of Critical Care Medicine consensus criteria of 1992, and 10 nonseptic ICU patients as control subjects. Interventions Kf was measured by venous congestion plethysmography, plasma nitrate/nitrite (NOx) by chemiluminescence, and neutrophil expression of α 4 -integrin (an index of neutrophil activation) by flow cytometry. Measurements and results Septic patients had higher Kf than nonseptic control subjects. Kf of septic patients was 5.6 ± 0.6 × 10 -3 mL·min -1 ·100 mL tissue -1 ·mm Hg -1 (mean ± SEM, mL·min -1 ·100 mL tissue -1 ·mm Hg -1 = Kf units [KfU]) as compared to 3.9 ± 0.5 × 10 -3 KfU in nonseptic ICU patients (p 4 -integrin expression and Kf in patients with sepsis. Septic patients with clinical evidence of edema had significantly higher Kf (p Conclusions ICU patients with severe sepsis have increased Kf, a noninvasive index of microvascular water permeability. The magnitude of hyperpermeability did not correlate with NOx levels or one index of neutrophil activation (α 4 -integrin expression). Presence of peripheral edema in these patients was associated with increased Kf, and may represent a simple, clinical indicator of altered microvascular permeability in sepsis.
Post-traumatic Stress in Children and Adolescents Exposed to Family Violence: I. Overview and Issues.

Exposure to child physical abuse and parents’ domestic violence can subject youth to pervasive traumatic stress and lead to Post-traumatic Stress Disorder (PTSD). The often repeating and ongoing nature of family violence exposure may result in youth exhibiting problems in multiple domains of functioning and meeting criteria for multiple disorders in addition to PTSD. These characteristics as well as unique factors related to children’s developmental level and symptom presentation complicate a PTSD diagnosis. This paper describes evolving conceptualizations in the burgeoning field of trauma related to family violence exposure, and reviews considerations that inform assessment and treatment planning for this population.
Basolateral membrane Na/base cotransport is dependent on CO2/HCO3 in the proximal convoluted tubule.

The mechanism of basolateral membrane base transport was examined in the in vitro microperfused rabbit proximal convoluted tubule (PCT) in the absence and presence of ambient CO2/HCO3- by means of the microfluorometric measurement of cell pH. The buffer capacity of the cells measured using rapid NH3 washout was 42.8 +/- 5.6 mmol.liter-1.pH unit-1 in the absence and 84.6 +/- 7.3 mmol.liter-1.pH unit-1 in the presence of CO2/HCO3-. In the presence of CO2/HCO3-, lowering peritubular pH from 7.4 to 6.8 acidified the cell by 0.30 pH units and lowering peritubular Na from 147 to 0 mM acidified the cell by 0.25 pH units. Both effects were inhibited by peritubular 4-acetamido-4'-isothiocyanostilbene-2,2'-disulfonate (SITS). In the absence of exogenous CO2/HCO3-, lowering peritubular pH from 7.4 to 6.8 acidified the cell by 0.25 pH units and lowering peritubular Na from 147 to 0 mM decreased cell pH by 0.20 pH units. Lowering bath pH from 7.4 to 6.8 induced a proton flux of 643 +/- 51 pmol.mm-1.min-1 in the presence of exogenous CO2/HCO3- and 223 +/- 27 pmol.mm-1.min-1 in its absence. Lowering bath Na from 147 to 0 mM induced proton fluxes of 596 +/- 77 pmol.mm-1.min-1 in its absence. The cell acidification induced by lowering bath pH or bath Na in the absence of CO2/HCO3- was inhibited by peritubular SITS or by acetazolamide, whereas peritubular amiloride had no effect. In the absence of exogenous CO2/HCO3-, cyanide blocked the cell acidification induced by bath Na removal, but was without effect in the presence of exogenous CO2/HCO3-. We reached the following conclusions. (a) The basolateral Na/base n greater than 1 cotransporter in the rabbit PCT has an absolute requirement for CO2/HCO3-. (b) In spite of this CO2 dependence, in the absence of exogenous CO2/HCO3-, metabolically produced CO2/HCO3- is sufficient to keep the transporter running at 30% of its control rate in the presence of ambient CO2/HCO3-. (c) There is no apparent amiloride-sensitive Na/H antiporter on the basolateral membrane of the rabbit PCT.
A Multitasking General Executive for Compound Continuous Tasks

As cognitive architectures move to account for increasingly complex real-world tasks, one of the most pressing challenges involves understanding and modeling human multitasking. Although a number of existing models now perform multitasking in real-world scenarios, these models typically employ customized executives that schedule tasks for the particular domain but do not generalize easily to other domains. This article outlines a general executive for the Adaptive Control of Thought-Rational (ACT-R) cognitive architecture that, given independent models of individual tasks, schedules and interleaves the models' behavior into integrated multitasking behavior. To demonstrate the power of the proposed approach, the article describes an application to the domain of driving, showing how the general executive can interleave component subtasks of the driving task (namely, control and monitoring) and interleave driving with in-vehicle secondary tasks (radio tuning and phone dialing).
An investigation of coded OFDM and CEOFDM waveforms utilizing different modulation schemes on HF channels

Constant envelope orthogonal frequency division multiplexing (CE-OFDM) is a modification to OFDM which eliminates the large peak power to average power ratio (PAPR) inherent in OFDM. For uncoded waveforms, CE-OFDM has been shown to offer some significant performance advantages over OFDM on high frequency (HF) multipath fading channels. However, when coding and interleaving are added to the waveforms, OFDM outperforms CE-OFDM on HF multipath fading channels, even after the PAPR of OFDM is included in the performance comparison. The results presented so far have only been for 2-ary phase shift keying (2-PSK) modulation. This paper will extend previous research by investigating the performance of coded OFDM and CE-OFDM waveforms using higher-order modulation schemes on various HF multipath fading channels.
The Polar T1 Interface Is Linked to Conformational Changes that Open the Voltage-Gated Potassium Channel

Abstract Kv voltage-gated potassium channels share a cytoplasmic assembly domain, T1. Recent mutagenesis of two T1 C–terminal loop residues implicates T1 in channel gating. However, structural alterations of these mutants leave open the question concerning direct involvement of T1 in gating. We find in mammalian Kv1.2 that gating depends critically on residues at complementary T1 surfaces in an unusually polar interface. An isosteric mutation in this interface causes surprisingly little structural alteration while stabilizing the closed channel and increasing the stability of T1 tetramers. Replacing T1 with a tetrameric coiled-coil destabilizes the closed channel. Together, these data suggest that structural changes involving the buried polar T1 surfaces play a key role in the conformational changes leading to channel opening.
Hyperphosphatemia due to fosphenytoin in a pediatric ESRD patient

Fosphenytoin is indicated for the treatment of generalized convulsions and seizures occurring during neurosurgery. Metabolites of fosphenytoin include phenytoin, phosphate, and formaldehyde. The drug monograph recommends caution in administering fosphenytoin to patients in whom phosphate restriction is necessary. Additionally, fosphenytoin has altered pharmacokinetics in end-stage renal disease patients. We report a 17-year old African-American male with end-stage renal disease who developed acute hyperphosphatemia to 3.9 mmol/L (12.1 mg/dL) following the intravenous administration of 1000 mg of fosphenytoin for an idiopathic complex partial seizure. To our knowledge, this is the first report of acute hyperphosphatemia due to fosphenytoin administration. Due to this risk of hyperphosphatemia, we recommend that fosphenytoin should be used with caution in the end-stage renal disease population.
A low-frequency high-voltage RF-barrier bunching system for high-intensity neutron source compressor rings

A Los Alamos design for a 1-MW pulsed neutron source incorporates a ring utilizing an RF-barrier bunching system. This bunching concept allows uniform longitudinal beam distributions with low momentum spread. Bunching cavities are operated at the revolution frequency (1.5 MHz in our case) and each of the 2nd, 3rd, 4th, and 5th revolution frequency harmonics. Their effects combine to maintain a beam free gap in the longitudinal distribution of the accumulated beam. The cavities are driven by low-plate-resistance common-cathode configured tetrode amplifiers incorporating local RF feedback. Additional adaptive feed-forward hardware is included to reduce the beam-induced bunching-gap voltages well below that achievable solely with RF feedback. Details of this system are presented along with a discussion of the various feed-back and feed-forward techniques incorporated.
Reply to Van Liew and Vann

to the editor: Van Liew and Vann ([19][1]) present several intravascular gas diffusion hypotheses and suspicions based on simulation data that they admit were indirectly tested and only validated by extravascular observations ([1][2]). The authors do acknowledge that “Nonbubble methods convince us
A Figure of Merit For Catheter Sampling Systems

The distortion of indicator dilution curves by catheter sampling systems is predictable from theoretic considerations based on laminar flow. Over a wide range of catheter and flow parameters, deductions can be made regarding distortion, by the arterial system or by sampling catheters, of indicator dilution curves coming from an idealized pump. A figure of merit for the sampling system is given by the volume of the catheter divided by twice the flow rate. This number should be less than the time in which significant changes in indicator concentration occur, i.e., the interval between pump strokes, if significant distortion of the indicator dilution curve is to be avoided.
On scheduling of multimedia services in a low-power MAC for wireless ATM networks

This paper describes the design and analysis of the scheduling algorithm for EC-MAC (energy conserving medium access control) (Sivalingam et al.), a low-power medium access control (MAC) protocol for wireless and mobile ATM networks. Based on the structure of EC-MAC and the characteristics of the wireless channel, we propose a new algorithm which can deal with the bursty errors and the location-dependent errors. Most scheduling algorithms proposed for either wired or wireless networks were analyzed with homogeneous traffic or multimedia services with simplified traffic models. We analyze our scheduling algorithm with more realistic multimedia traffic models. One of the key goals of the scheduling algorithm is simplicity and fast implementation. Unlike the time-stamp based algorithm, our algorithm does not need to sort the virtual time, thus reducing the complexity of the algorithm significantly.
Balanced POD algorithm for robust control design for linear distributed parameter systems

A mathematical model of a physical system is never perfect; therefore, robust control laws are necessary for guaranteed stabilization of the nominal model and also “nearby” systems, including hopefully the actual physical system. We consider the computation of a robust control law for large-scale finite dimensional linear systems and a class of linear distributed parameter systems. The controller is robust with respect to left coprime factor perturbations of the nominal system. We present an algorithm based on balanced proper orthogonal decomposition to compute the nonstandard features of this robust control law. Numerical results are presented for a convection diffusion partial differential equation.