bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of relaxation and elasticity in polymer glasses
Authors: Chen Kang , Schweizer Kenneth S.
Published: January 2007

The recently developed activated barrier hopping theory of deeply supercooled polymer melts [K. S. Schweizer and E. J. Saltzman, J. Chem. Phys. 121, 1984 (2004)] is extended to the nonequilibrium glass state. Below the kinetic glass temperature Tg, the exact statistical mechanical relation between the dimensionless amplitude of long wavelength density fluctuations, S0, and the thermodynamic compressibility breaks down. Proper extension of the theory requires knowledge of the nonequilibrium S0 which x-ray scattering experiments find to consist of a material specific and temperature-independent quenched disorder contribution plus a vibrational contribution which varies roughly linearly with temperature. Motivated by these experiments and general landscape concepts, a simple model is proposed for S0(T). Deep in the glass state the form of the temperature dependence of the segmental relaxation time is found to depend sensitively on the magnitude of frozen in density fluctuations. At the (modest) sub-Tg temperatures typically probed in experiment, an effective Arrhenius behavior is generically predicted which is of nonequilibrium origin. The change in apparent activation energy across the glass transition is determined by the amplitude of frozen density fluctuations. For values of the latter consistent with experiment, the theory predicts a ratio of effective activation energies in the range of 3–6, in agreement with multiple measurements. Calculations of the shear modulus for atactic polymethylmethacrylate above and below the glass transition temperature have also been performed. The present work provides a foundation for the formulation of predictive theories of physical aging, the influence of deformation on the alpha relaxation process, and rate-dependent nonlinear mechanical properties of thermoplastics.
Efficient source of high purity polarization-entangled photon pairs in the 1550nm telecommunication band
Authors: Noh Tae-Gon , Kim Heonoh , Zyung Taehyoung , Kim Jaewan
Published: January 2007

The authors present an efficient source of high purity polarization-entangled photon pairs in the standard 1550nm telecommunication band using a type-II degenerate parametric downconversion process. They first measured the spatial intensity distributions of the downconverted light to verify the beamlike, collinear, and noncollinear generations at the 1550nm wavelength. All four Bell states could easily be generated by selecting the intersection of two downconverted light cones in the noncollinear phase matching. They observed two-photon fringe visibilities of up to 98±3% and violations of Bell’s inequality by up to nine standard deviations when the accidental coincidences were subtracted.
Observation of low optical overlap mode propagation in nanoscale indium phosphide membrane waveguides
Authors: Whaley R. D. , Kwakernaak M. H. , Khalfin V. B. , Lipp S. A. , Chan W. K. , An H. , Abeles J. H.
Published: January 2007

The authors have developed a nanoscale, rib-loaded waveguide that propagates a low optical overlap mode (LOOM) in which less than 1% of the modal field energy resides in the semiconductor material. Because of the small modal fill factor, the potential for extremely low waveguide propagation loss, on the order of 0.001dB or less, is predicted. Elevated membrane waveguides, 50nm thick with a 50nm thick rib, have been fabricated in InP using a multistep microelectromechanical release process. Both transverse electric and transverse magnetic LOOM propagations have been observed and measurements are compared to theoretical predictions.
Dynamic optimization of on-chip polymerase chain reaction by monitoring intracycle fluorescence using fast synchronous detection
Authors: Mondal Sudip , Paul Debjani , Venkataraman V.
Published: January 2007

The authors report on-chip dynamic optimization of polymerase chain reaction (PCR) based on a feedback technique utilizing synchronous detection of intracycle fluorescence every 500ms. From a direct measurement of polymerase activity, the authors determine the optimum extension temperature. The authors dynamically optimize PCR in an inductively heated microchip by sensing the saturation of extension in each cycle and applying the feedback. They demonstrate that, even with fast ramp rates, dynamic optimization leads to faster reactions compared to fixed-duration extension protocols for long DNA (>500bp). This optimization scheme uses a fairly universal dye Sybr Green I and can be applied to most PCRs.
Os
N
2
: Crystal structure and electronic properties
Authors: Montoya Javier A. , Hernandez Alexander D. , Sanloup Chrystèle , Gregoryanz Eugene , Scandolo Sandro
Published: January 2007

Osmium nitride belongs to a family of nitrides synthesized recently at high pressures from their parent elements. Here we show, based on first-principles calculations, that the crystal structure of osmium nitride is isostructural to marcasite. Excellent agreement is obtained between the authors’ results and x-ray, Raman, and compressibility measurements. In the OsN2 marcasite structure single-bonded N2 units occupy the interstitial sites of the Os close-packed lattice, giving rise to a metallic compound. A comparison between the formation energies of OsN2 and PtN2 explains the similar thermodynamic conditions of formation reported experimentally for the two compounds.
SChiSM2: creating interactive web page annotations of molecular structure models using Jmol
Authors: Cammer Stephen
Published: January 2007

Summary: SChiSM2 is a web server-based program for creating web pages that include interactive molecular graphics using the freely-available applet, Jmol, for illustration. The program works with Internet Explorer and Firefox on Windows, Safari and Firefox on Mac OSX and Firefox on Linux.

Availability: The program can be accessed at the following address:

Contact:  cammer@vbi.vt.edu
Archaebacterial reverse gyrase cleavage-site specificity is similar to that of eubacterial DNA topoisomerases I
Authors: Kovalsky O.I. , Kozyavkin S.A. , Slesarev A.I.
Published: January 2007

ATP-dependent type I topoisomerases from extremely thermophllic archaebacterla - reverse gyrases - drive positive supercoiling of DNA. We showed that reverse gyrase from Desulfurococcus amylolytlcus breaks the DNA at specific sites and covalentty binds to the 5′ end. In 30 out of 31 sites located in pBR322 DNA fragments, cleavage occurs at the sequence 5′–CNNN∣–(N is any base). The same rule was previously shown to hold for single-stranded DNA breakage by eubacterial topoisomerases I. The relative cleavage frequencies at different sites depend on Mg 2+ and temperature. We discuss the possible physiological and mechanistic role of the above specificity of the bacterial topoisomerases I.
Disrupting the timing of
Wolbachia
-induced male-killing
Authors: Charlat Sylvain , Davies Neil , Roderick George K , Hurst Gregory D.D
Published: January 2007

Several lineages of maternally inherited symbionts have evolved the ability to kill infected females' sons, a phenomenon known as male-killing. Male-killing varies in its timing, from early (death during embryogenesis) to late (mortality of late larval instars). Following the observation that treatment of male-killer infected adult females
Hypolimnas bolina
with tetracycline, a bacteriostatic antibiotic, produces a delay in the timing of male death, we hypothesized that early male-killers possess the ability to kill males through bacterial activity outside of embryogenesis. We verified this hypothesis by showing that treatment of surviving larvae with the bacteriocidal antibiotic rifampicin rescues males. This discounted the hypothesis that delayed death occurred due to postponed effects of toxins produced at earlier stages, and thus supported the importance of bacterial activity in the larval phase in delayed male-killing. These results argue against the view that early male-killing is achieved by specifically targeting an early developmental process within the sex determination pathway.
Social competitiveness associated with rapid fluctuations in sperm quality in male fowl
Authors: Pizzari Tommaso , Cornwallis Charles K , Froman David P
Published: January 2007

When females copulate with multiple males, paternity is determined by the competitive ability of a male to access females and by the ability of its ejaculates to out-compete those of other males over fertilization. The relationship between the social competitiveness of a male and the fertilizing quality of its sperm has therefore crucial implications for the evolution of male reproductive strategies in response to sexual selection. Here, we present a longitudinal experimental study of the relationship between social status and sperm quality. We monitored sperm quality in socially naive male domestic fowl,
Gallus gallus domesticus
, before and after exposure to a social challenge which comprised two stages. In the first stage, social dominance was established in male pairs divergent in sperm quality, and in the second, social status was experimentally manipulated by re-shuffling males across pairs. We show that sperm quality fluctuates within males both before and after a social challenge. Importantly, such fluctuations followed consistently different patterns in males that displayed different levels of social competitiveness in the social challenge. In particular, following the social challenge, sperm quality dropped in males that won both contests while the sperm quality of males that lost both contests remained constant. Together, these results indicate that males of different social competitiveness are predisposed to specific patterns of fluctuations in sperm quality. These rapid within-male fluctuations may help explain the recent findings of trade-offs between male social and gametic competitive abilities and may help maintain phenotypic variability in these traits.
Interannual variability and intraannual stability of the otolith shape in European anchovy Engraulis encrasicolus (L.) in the Bay of Biscay
Authors: Gonzalez‐Salas C. , Lenfant P.
Published: January 2007

In this study 1047 samples of European anchovy Engraulis encrasicolus caught in 2001, 2002 and 2003 in different areas of the Bay of Biscay were examined using otolith shape analysis. For the years 2001 and 2003, 1 year‐old individuals were dominant, whereas for the year 2002 they were less common; in contrast 2 year‐old individuals represented 74% of the total individuals, suggesting that the fisheries in 2002 were mainly supported by the strong recruitment of 2000. The classification success of the discriminant analysis indicated a strong separation between year groups (P < 0·001), overall, 98% of individuals were correctly classified. Results from both jackknife and Cohen’s kappa procedures confirmed the high rates of classification success obtained by the discriminant analysis (99 and 97%, respectively). Stability in the intraannual shape analysis leads to the idea that individuals were affected by the same intraannual environmental conditions in the Bay of Biscay. Variability in the interannual shape analysis could indicate that the spawning population is composed of European anchovy from different origins every year. In general differences observed suggested that the European anchovy in the Bay of Biscay were members of three or more different communities or entities.
Diel and spatial drifting patterns of silver perch Bidyanus bidyanus eggs in an Australian lowland river
Authors: Tonkin Z. , King A. , Mahoney J. , Morrongiello J.
Published: January 2007

Densities of silver perch Bidyanus bidyanus eggs drifting in the Murray River, Australia, suggested a peak spawning time between 2100 and 0100 hours, and a propensity to drift in higher densities near shore and at the bottom of the water column. The results highlight the need to consider such spatial and temporal patterns when estimating species‐specific drift abundances.
1D and 2D Cole‐Cole‐inversion of time‐domain induced‐polarization data
Authors: Hönig Mark , Tezkan Bülent
Published: January 2007

A new method for the 2D inversion of induced polarization (IP) data in the time domain has been developed. The entire IP transients were observed and inverted into 2D Cole‐Cole earth models, including resistivity, chargeability, relaxation time and the frequency constant. Firstly, a modified 1D time‐domain electromagnetic algorithm was used to calculate the response of a layered polarizable ground. The transient signals were then inverted using the Marquardt method to derive the Cole‐Cole parameters of each layer. However, model calculations showed that the EM effects could be neglected for the time range (>1 ms) and for the transmitter–receiver distances (<50 m) used in this study. Therefore, the induction effects were not considered for the solution of the 2D inverse problem and a DC solution was applied. An approximative forward algorithm was introduced in order to calculate the IP transients directly in the time domain and in order to speed up the inverse procedure. The approximation is highly accurate, and this is demonstrated by comparing the approximations with their exact solutions up to 3D.

The inverse algorithm presented consists of two steps. The transient voltages of an array data set were inverted separately into a two‐dimensional resistivity model for each time channel. The time‐dependent resistivity of each cell was then interpreted as the response of a homogeneous half‐space. In the 2D inversion algorithm, a 3D DC algorithm was used as a forward operator. The method only requires a standard 2D DC inversion and a homogenous half‐space Cole‐Cole inversion.

The developed algorithm has been successfully applied to synthetic data sets and to a field data set obtained from a waste site situated close to Düren in Germany.
Validity of the long‐wave approximation in periodically layered media
Authors: Arntsen Borge
Published: January 2007

In seismic modelling, a stack of thin layers is often replaced by an effective equivalent anisotropic homogeneous slab. For waves with finite wavelength, this is an approximation, and the error thus introduced can be quantified by considering the relative error in the phase velocity between the layer stack and the effective medium. For periodic layering, the relative phase‐velocity error can be expressed in closed form as a function of wavelength, reflection coefficients and layer thicknesses. By comparing the relative phase‐velocity error with laboratory measurements and numerical simulations, we find that the difference in seismic response between a periodic layer stack and an equivalent effective medium depends not only on wavelength, but it also depends significantly on reflection coefficients and the ratio between layer thicknesses. For a 1% relative error in the phase velocity, and if all layers have the same thickness measured in vertical traveltime, we find that the wavelength must be larger than approximately three times the layer period for a reflection coefficient of 0.1, but this increases to 13 times the layer period for a reflection coefficient of 0.9, which is highly unrealistic in a geological setting.
Intravenous and intramuscular pharmacokinetics of a single‐daily dose of disodium–fosfomycin in cattle, administered for 3 days
Authors: SUMANO L. H. , OCAMPO C. L. , GUTIERREZ O. L.
Published: January 2007

Pharmacokinetic parameters of fosfomycin in cattle were determined after administration of buffered disodium fosfomycin either intravenously (i.v.) or intramuscularly (i.m.) at a dose of 20 mg/kg/day for 3 days. Calculated concentrations at time zero and maximum serum concentrations were 34.42 and 10.18 μg/mL, respectively. The variables determined, the elimination half‐life of the drug remained unchanged during the 3 days ( = 1.33 ± 0.3 h for the i.v. route and = 2.17 ± 0.4 h for the i.m. route). Apparent volumes of distribution suggest moderated distribution out of the central compartment (Vdarea = 673 mL ± 27 mL/kg andVdss = 483 ± 11 mL/kg). Bioavailability after i.m. administration was 74.52%. Considering fosfomycin as a time‐dependent antibacterial drug, plasma concentration vs. time profiles obtained in this study, suggest that clinically effective plasma concentrations of fosfomycin could be obtained for up to 8 h following i.v. administration and approximately 10 h after i.m. injection of 20 mg/kg, for susceptible bacteria. In addition to residue studies in milk and edible tissues, a series of clinical assessments, using fosfomycin at 20 mg/kg b.i.d. or t.i.d. are warranted before this antibacterial drug should be considered for use in cattle.
A competitive enzyme‐linked immunosorbent assay for determination of chloramphenicol
Authors: WESONGAH J. O. , MURILLA G. A. , GUANTAI A. N. , ELLIOT C. , FODEY T. , CANNAVAN A.
Published: January 2007

Chloramphenicol is a broad‐spectrum antibiotic shown to have specific activity against a wide variety of organisms that are causative agents of several disease conditions in domestic animals. Chloramphenicol has been banned for use in food‐producing animals for its serious adverse toxic effects in humans. Due to the harmful effects of chloramphenicol residues livestock products should be free of any traces of these residues. Several analytical methods are available for chloramphenicol analysis but sensitive methods are required in order to ensure that no traces of chloramphenicol residues are present in edible animal products. In order to prevent the illegal use of chloramphenicol, regulatory control of its residues in food of animal origin is essential. A competitive enzyme‐linked immunosorbent assay for chloramphenicol has been locally developed and optimized for the detection of chloramphenicol in sheep serum. In the assay, chloramphenicol in the test samples and that in chloramphenicol‐horseradish peroxidase conjugate compete for antibodies raised against the drug in camels and immobilized on a microtitre plate. Tetramethylbenzidine‐hydrogen peroxide (TMB/H2O2) is used as chromogen‐substrate system. The assay has a detection limit of 0.1 ng/mL of serum with a high specificity for chloramphenicol. Cross‐reactivity with florfenicol, thiamphenicol, penicillin, tetracyclines and sulfamethazine was not observed. The assay was able to detect chloramphenicol concentrations in normal sheep serum for at least 1 week after intramuscular injection with the drug at a dose of 25 mg/kg body weight (b.w.). The assay can be used as a screening tool for chloramphenicol use in animals.
Pharmacokinetics and milk penetration of difloxacin after intravenous, subcutaneous and intramuscular administration to lactating goats
Authors: MARÍN P. , ESCUDERO E. , FERNÁNDEZ‐VARÓN E. , CÁRCELES C. M.
Published: January 2007

The single‐dose disposition kinetics of difloxacin were determined in clinically normal lactating goats (n = 6) after intravenous (i.v.), subcutaneous (s.c.) and intramuscular (i.m.) administration of 5 mg/kg. Difloxacin concentrations were determined by high performance liquid chromatography with fluorescence detection. The concentration–time data were analysed by compartmental and noncompartmental kinetic methods. Steady‐state volume of distribution (Vss) and total body clearance (Cl) of difloxacin after i.v. administration were estimated to be 1.16 ± 0.26 L/kg and 0.32 ± 0.05 L/h·kg respectively. Following s.c. and i.m. administration difloxacin achieved maximum plasma concentrations of 1.33 ± 0.25 and 1.97 ± 0.40 mg/L at 3.37 ± 0.36 and 1.79 ± 1.14 h respectively. The absolute bioavailabilities after s.c. and i.m. routes were 90.16 ± 11.99% and 106.79 ± 13.95% respectively. Difloxacin penetration from the blood into the milk was extensive and rapid, and the drug was detected for 36 h after i.v. and s.c. dosing, and for 72 h after i.m. administration.
Phosphate‐dependent modulation of c‐di‐GMP levels regulates Pseudomonas fluorescens Pf0‐1 biofilm formation by controlling secretion of the adhesin LapA
Authors: Monds Russell D. , Newell Peter D. , Gross Robert H. , O'Toole George A.
Published: January 2007

Biofilm formation is commonly described as a developmental process regulated by environmental cues. In the current study we present a mechanistic model to explain regulation of Pseudomonas fluorescens biofilm formation by the environmentally relevant signal inorganic phosphate (Pi). We show that activation of the Pho regulon, the major pathway for adaptation to phosphate limitation, results in conditional expression of a c‐di‐GMP phosphodiesterase referred to as RapA. Genetic analysis indicated that RapA is an inhibitor of biofilm formation and required for loss of biofilm formation in response to limiting Pi. Our results suggest that RapA lowers the level of c‐di‐GMP, which in turn inhibits the secretion of LapA, a large adhesion required for biofilm formation by P. fluorescens. The ability of c‐di‐GMP to modulate protein secretion is a novel finding and further extends the biological influence of c‐di‐GMP beyond that of regulating exopolysaccharide synthesis and motility. Interestingly, Pho regulon expression does not impinge on the rate of attachment to a surface but rather inhibits the transition of cells to a more stable interaction with the surface. We hypothesize that Pho regulon expression confers a surface‐sensing mode on P. fluorescens and suggest this strategy may be broadly applicable to other bacteria.
Regulation of virulence in Bacillus anthracis: the phosphotransferase system transmits the signals
Authors: Stülke Jörg
Published: January 2007

Bacillus anthracis causes host damage by producing two toxins, the lethal factor and the oedema factor. Their production and that of other virulence factors depend on the activity of the AtxA transcription factor. The mechanisms that control AtxA activity are reported in this issue of Molecular Microbiology. The protein can be phosphorylated at two distinct sites by components of the phosphotransferase system (PTS). One phosphorylation event stimulates transcription activation by AtxA, whereas the second prevents AtxA activity. This mode of regulation and the predicted domain structures are highly similar to transcription regulators controlled by PTS regulation domains (PRDs). Thus, the phosphorylated domains of AtxA represent a novel form of PRDs. As a similar organization is found in transcription regulators in many other pathogens, AtxA might become the paradigm of a new class of virulence regulators.
Personality Development From Late Adolescence to Young Adulthood: Differential Stability, Normative Maturity, and Evidence for the Maturity‐Stability Hypothesis
Authors: Donnellan M. Brent , Conger Rand D. , Burzette Rebecca G.
Published: January 2007

ABSTRACT
This investigation examined personality development during the transition from adolescence to adulthood using the brief form of the Multidimensional Personality Questionnaire (Patrick, Curtin, & Tellegen, 2002). Parent and self‐reports of personality were obtained in 1994 (average age=17.60 years), and self‐reports were obtained in 2003 (average age=27.24 years). There was evidence of both differential stability and normative changes in the direction of increased functional maturity during this transition. Moreover, adolescents with more mature personalities in 1994 tended to show fewer personality changes from 1994 to 2003. These maturity‐stability effects held when parent reports were used to assess personality. All told, there was evidence of both stability and change in personality during the transition to adulthood.
Conductance-Controlled Point Functionalization of Single-Walled Carbon Nanotubes
Authors: Goldsmith Brett R. , Coroneus John G. , Khalap Vaikunth R. , Kane Alexander A. , Weiss Gregory A. , Collins Philip G.
Published: January 2007

We used covalent attachments to single-walled carbon nanotubes (SWNTs) to fabricate single-molecule electronic devices. The technique does not rely on submicrometer lithography or precision mechanical manipulation, but instead uses circuit conductance to monitor and control covalent attachment to an electrically connected SWNT. Discrete changes in the circuit conductance revealed chemical processes happening in real time and allowed the SWNT sidewalls to be deterministically broken, reformed, and conjugated to target species. By controlling the chemistry through electronically controlled electrochemical potentials, we were able to achieve single chemical attachments. We routinely functionalized pristine, defect-free SWNTs at one, two, or more sites and demonstrated three-terminal devices in which a single attachment controls the electronic response.
Differential Antigen Processing by Dendritic Cell Subsets in Vivo
Authors: Dudziak Diana , Kamphorst Alice O. , Heidkamp Gordon F. , Buchholz Veit R. , Trumpfheller Christine , Yamazaki Sayuri , Cheong Cheolho , Liu Kang , Lee Han-Woong , Park Chae Gyu , Steinman Ralph M. , Nussenzweig Michel C.
Published: January 2007

Dendritic cells (DCs) process and present self and foreign antigens to induce tolerance or immunity. In vitro models suggest that induction of immunity is controlled by regulating the presentation of antigen, but little is known about how DCs control antigen presentation in vivo. To examine antigen processing and presentation in vivo, we specifically targeted antigens to two major subsets of DCs by using chimeric monoclonal antibodies. Unlike CD8
+
DCs that express the cell surface protein CD205, CD8
–
DCs, which are positive for the 33D1 antigen, are specialized for presentation on major histocompatibility complex (MHC) class II. This difference in antigen processing is intrinsic to the DC subsets and is associated with increased expression of proteins involved in MHC processing.
Inhibition of JNK activation prolongs survival after smoke inhalation from fires
Authors: Syrkina Olga L. , Quinn Deborah A. , Jung Walter , Ouyang Bin , Hales Charles A.
Published: January 2007

Initial injury from smoke inhalation is mainly to the trachea and bronchi and is characterized by mucosal hyperemia and increased microvascular permeability, exfoliation of epithelial lining, mucous secretion, mucous plugging, and an acute inflammatory cell influx. In this study, we explore the role of the c-Jun N-terminal protein kinase (JNK) pathway in smoke inhalation lung injury using a rat model of exposure to smoke from burning cotton. Male Sprague-Dawley rats were exposed to smoke from burning cotton for 15 min, and 1 h after injury a JNK inhibitor (SP-600125) or vehicle was injected. We measured neutrophil influx, cytokine release, percent of apoptotic cells, airway plugging, and survival. Administration of a JNK inhibitor 1 h after smoke inhalation decreased airway apoptosis, mucous plugging, influx of inflammatory cells, and the release of cytokines and significantly prolonged animal survival ( P < 0.05). These in vivo data show that the JNK pathway plays a critical role in smoke-induced lung injury and offer an attractive therapeutic approach for this injury.
Applications of a Blood-Brain Barrier Technology Platform to Predict CNS Penetration of Various Chemotherapeutic Agents. 1. Anti-Infective Drugs
Authors: Adenot M. , Perriere N. , Scherrmann J.M. , Lahana R.
Published: January 2007

Except for a few well-documented CNS therapeutics, quantitative data on blood-brain barrier (BBB) permeation is incomplete, unreliable or nonexistent and this is a major impediment in BBB modeling. Furthermore, only the passive diffusion component is generally taken into account. Three techniques of modeling (in vivo, in vitro and in silico) were set up and compared. The in silico predicted permeation of 287 anti-infective drugs has been faced to clinical observations. Good correlations were observed between in vitro permeability coefficients, influx transfer coefficients from in vivo studies and Pe scores from the computational model. High Pe score values are associated with an increase of reported CNS side effects.
Risk Factors for Sudden Cardiac Death in Patients with Chronic Renal Insufficiency and Left Ventricular Dysfunction
Authors: Chonchol Michel , Goldenberg Ilan , Moss Arthur J. , McNitt Scott , Cheung Alfred K.
Published: January 2007

Background: Patients with ischemic left ventricular dysfunction have a high risk of sudden cardiac death (SCD). It is, however, unclear if the risk and risk factors of SCD in these patients is modulated by the coexistence of mild chronic renal insufficiency. Methods: We performed a post-hoc analysis of the outcome associated with mild renal dysfunction, as defined by an estimated glomerular filtration rate (eGFR) of <75 ml/min/1.73 m2 in patients allocated to the conventional medical therapy arm of the Multicenter Automatic Defibrillator Implantation Trial-II. Results: In multivariable analysis, renal dysfunction was independently associated with significant increased risks for all-cause mortality (hazard ratio [HR] = 1.86; 95% CI 1.13–3.05) and SCD (HR = 2.00; 95% CI 1.01–4.02), but not non-SCD, compared to patients without renal dysfunction. Independent predictors of SCD in patients with renal dysfunction were: increased resting heart rate (HR = 2.40; 95% CI 1.50–3.86); low diastolic blood pressure (HR = 3.23; 95% CI 1.52–6.66), and a prolonged QRS duration (HR = 1.63; 95% CI 1.02–2.61). β-Blocker therapy was independently associated with a significant reduction in the risk of SCD in patients with an eGFR of <75 ml/min/1.73 m2 (HR = 0.61; 95% CI 0.38–0.99). Conclusion: These findings suggest that renal dysfunction significantly increases the risk for SCD in patients with left ventricular dysfunction, and that β-blocker therapy reduces the risk of arrhythmic mortality in heart failure patients with coexisting renal insufficiency.
The Basal Ganglia and Cortex Implement Optimal Decision Making Between Alternative Actions
Authors: Bogacz Rafal , Gurney Kevin
Published: January 2007

Neurophysiological studies have identified a number of brain regions critically involved in solving the problem of action selection or decision making. In the case of highly practiced tasks, these regions include cortical areas hypothesized to integrate evidence supporting alternative actions and the basal ganglia, hypothesized to act as a central switch in gating behavioral requests. However, despite our relatively detailed knowledge of basal ganglia biology and its connectivity with the cortex and numerical simulation studies demonstrating selective function, no formal theoretical framework exists that supplies an algorithmic description of these circuits. This article shows how many aspects of the anatomy and physiology of the circuit involving the cortex and basal ganglia are exactly those required to implement the computation defined by an asymptotically optimal statistical test for decision making: the multihypothesis sequential probability ratio test (MSPRT). The resulting model of basal ganglia provides a new framework for understanding the computation in the basal ganglia during decision making in highly practiced tasks. The predictions of the theory concerning the properties of particular neuronal populations are validated in existing experimental data. Further, we show that this neurobiologically grounded implementation of MSPRT outperforms other candidates for neural decision making, that it is structurally and parametrically robust, and that it can accommodate cortical mechanisms for decision making in a way that complements those in basal ganglia.
The Processing of Analogous Problems in the Verbal and Visual-Humorous (Cartoons) Modalities by Gifted/Average Children
Authors: Klavir Rama , Gorodetsky Malka
Published: January 2007

Children encounter problem solving in their formal schooling mainly in the verbal modality, whereas they are exposed to cartoons in their leisure time in a context perceived as nonlearning and nonthreatening. Yet, cartoons can be conceived of as problems in the visual-humorous modality, analogous to verbal problems. This article examines how gifted and average children solve analogous problems in these two modalities (verbal and visual-humorous), including their ability to consciously transfer solutions from one modality to the other. Specifically, four variables are considered: (1) the correctness of solutions of analogous problems in both modalities; (2) the students' perceived difficulty of these problems; (3) their awareness of the correctness of their solutions; and (4) their awareness of the contribution of a learned source problem in one modality to the solution of an analogous target problem in the other. Gifted children, as expected, did better on the verbal problems, but improved their skills in both modalities once exposed to the solution of analogous problems In the visual-humorous modality. Average children tended to solve cartoons better than verbal problems, but working with cartoons increased their verbal problem-solving skills. Results suggest that cartoon solving in the classroom can enhance the problem-solving capabilities of both populations.
Early-Entrance Students: Impressions of Their First Semester of College
Authors: Muratori Michelle , Colangelo Nicholas , Assouline Susan
Published: January 2007

Although the long-term impact of early entrance to college has been examined, one issue that has received inadequate attention in the gifted education literature is how students enrolled in early-entrance programs adjust during their first semester of college, which is arguably the most critical juncture for them in terms of their transition from high school. The purpose of this study was to identify the unique academic, social, family, and transition issues that challenged the inaugural class of the National Academy of Arts, Sciences, and Engineering (NAASE), an early-entrance program at the University of Iowa. Through the use of in-depth interviews, behavioral observations, and student and parent surveys, a rich picture of the students' satisfaction and challenges with their first-semester college experiences emerged. While the primary aim of this research was to examine the NAASE students' first-semester adjustment, the study also served to evaluate the effectiveness of the NAASE program from the students' perspectives.
Exploring Teacher Biases When Nominating Students for Gifted Programs
Authors: Siegle Del , Powell Teri
Published: January 2007

The purpose of this study was to identify student characteristics that might influence teachers in referring students for gifted programs. We developed a series of 12 student profiles to measure teacher bias and asked teachers to indicate how strongly they believed the students in the profiles should or should not be recommended for their district gifted program. We found the ability to do mental computations overshadowed completion of schoolwork, and the esoteric nature of student interest appeared to be equivalent to completion of schoolwork. We found that completing schoolwork was not a factor when students possessed a large storehouse of information. We also learned that classroom teachers may be more inclined than gifted specialists to focus on student weaknesses, rather than student strengths.
Medication Use and Symptoms in Individuals With Mitral Valve Prolapse Syndrome
Authors: Scordo Kristine A.
Published: January 2007

Mitral valve prolapse (MVP) is a common valvular heart disease associated with a variety of frightening symptoms. Beta-adrenergic blockers along with calcium channel blockers and anxiolytics are widely used to treat symptoms associated with MVPS despite a lack of evidence that supports their efficacy. This study examined the relationship between prescribed medication use and frequency and intensity of MVPS symptoms. A descriptive cross-sectional survey design was used. Descriptive statistics and Cramèr’s V correlational analysis were used to answer the research questions. Self-completed questionnaires were mailed to 2,282 MVPS individuals older than 21 years of age throughout the United States and Canada previously diagnosed with MVPS. Of the 837 participants, 337 (40%) were taking one or more medications. Although there were significant positive correlations between anxiety and calcium channel blockers, chest pain and digoxin, and mood swings and digoxin, the correlations were very weak.
Crime and Punishment: The Politics of Federal Criminal Justice Sanctions
Authors: Nicholson-Crotty Sean , Meier Kenneth J.
Published: January 2007

The incarceration rate in federal penitentiaries has tripled in the past twenty-five years, marking an unprecedented incursion by the federal government into what was the near exclusive domain of sub-national jurisdictions. Numerous scholars, particularly outside the field of political science, have hypothesized about the causes of the burgeoning prison population; but few have systematically tested these propositions. Borrowing insights from organizational theory and the literature on bureaucratic politics, this article proposes a frame-work that incorporates the most plausible hypotheses from the literature and empirically models the environmental, structural, and political influences on the implementation of federal criminal justice sanctions. The analysis demonstrates that federal incarceration rates are largely uncorrelated with the national crime rate, but that other variables significantly affect the number of commitments, the average sentence of convicted prisoners, and the number of paroles annually. The model also reveals that the outputs of criminal justice bureau-cracies are extremely autoregressive, with current sanctions determined largely by past agency behavior.
Delaying Justice: The Supreme Court’s Decision to Hear Rearguments
Authors: Hoekstra Valerie , Johnson Timothy
Published: January 2007

Some of the Supreme Court’s most famous cases—from Roe v. Wade (1973) to Brown v. Board of Education (1954)—have been decided only after being held over and argued a second time. While few cases take this path, scholars have offered no systematic account for why the Court would ever take such a tack. We develop hypotheses about when reargument is most likely to occur, and test them on all formally decided cases between 1946 and 1985. More specifically, we focus on how justices’ uncertainty about case outcomes affects the Court’s decision to seek reargument. Our findings demonstrate that reargument is most likely to occur when multiple levels of uncertainty are present, even when we control for other factors that have been raised as explanations for this phenomenon.
Reevaluating Spending in Gubernatorial Races: Job Approval as a Baseline for Spending Effects
Authors: Bardwell Kedron
Published: January 2007

Research on campaign spending has tried to resolve the issue of differential effects for incumbent and challenger spending. This analysis offers two new perspectives to the spending effects literature: (1) It extends the scope of this research to include gubernatorial elections, and (2) it uses job approval ratings to control for governors’ popularity. This approval measure sets a pre-campaign baseline for the expected vote that keeps campaign variables from being credited with pre-existing levels of incumbent popularity. A two-stage least squares (TSLS) analysis of two decades of gubernatorial races shows that incumbent spending (unlike challenger spending) does not have a significant effect on the vote. If incumbent spending wins little new support in the course of campaigns, generous public funding for statewide candidates will boost spending by challengers without reducing challenger competitiveness via higher incumbent spending.
Presidents and the Economic Agenda
Authors: Eshbaugh-Soha Matthew , Peake Jeffrey S.
Published: January 2007

The president’s ability to influence the national policy agenda is an important component of presidential power. Although some maintain that presidents are favorably situated to set agendas, others demonstrate that the president’s agenda-setting skills vary considerably by policy area. What is more, scholars have yet to examine the impact presidents have had focusing attention on the economy, an issue of vital importance to their political success. Extending previous research on presidential agenda setting that did not address economic policy (Edwards and Wood 1999; Wood and Peake 1998), we test the impact that the president’s public statements on the economy have on media and congressional attention to the economy. Using Vector Autoregression (VAR), we demonstrate that although presidents have some influence over the economic agenda, presidents are primarily responsive to media coverage of the economy.
The Effects of Information on the Accuracy of Presidential Assessments of Supreme Court Nominee Preferences
Authors: Szmer John , Songer Donald R.
Published: January 2007

Models of presidential success in the judicial appointment process assume that a president selects a nominee who will maximize his influence on the Court. The models assume that the president accurately assesses the preferences of potential nominees. We argue that these perceptions are subject to systematic errors. Specifically, the amount of information available to the evaluator (the president and his staff) of a Supreme Court nominee's policy preferences affects the accuracy of the evaluation. These models assume that the president and/or his staff can accurately predict the policy preferences of the potential nominees. We argue that the precision of these assessments is a function of the information available to the president and his staff. We test this hypothesis using the prior experience of the nominee as a measure of the information available to the president and those members of his staff assigned to investigate potential Supreme Court nominees. Using heteroskedastic probit, we find a significant relationship between the amount of information (measured as prior legislative, executive, judicial, and academic experience) and the accuracy of the assessments of the nominees' preferences. This relationships hold even after controlling for various factors including the salience the president attaches to the issues decided by the justice and the relative relationship between the preferences of the president, Senate, and the remaining sitting justices when the nomination was made.
Political Legitimacy and Participation in Costa Rica: Evidence of Arena Shopping
Authors: Booth John A. , Seligson Mitchell A.
Published: January 2007

Considerable research has failed to establish a link between political legitimacy and system breakdown. This does not mean, however, that researchers should abandon the concept of legitimacy altogether, since it may have other important effects that shape the character of the political system. We explore the impact, or lack thereof, of legitimacy on citizen behavior. Specifically, we test the proposition that legitimacy may have complex effects by differentially affecting a variety of modes of citizen participation. Empirical evidence from a 2002 national survey in Costa Rica, a consolidated Latin American democracy, reveals how legitimacy shapes citizens’ political participation and civil society activism. We find that legitimacy has no uniform relationship across diverse modes of political participation. Some legitimacy dimensions increase certain participation modes while they decrease others, but have yet no effect on other modes. Specifically, other factors held constant, greater belief in two dimensions of legitimacy, “political community” and “trust in local government,” increase voting and civil society activism. Low rather than high levels of “system support” increase party activism-instrumental contacting and communal activism, and low trust in regime institutions elevates civil society activism. Contradictory findings emerge on the impact of low legitimacy on protest participation. An important and novel finding is that two legitimacy-participation relationships are curvilinear. These findings suggest that prior research, based on a unidimensional notion of legitimacy and binary treatment of participation as conventional vs. unconventional may have been misleading. We discuss the implications of these patterns for political stability and legitimacy theory.
Position-Taking and Electoral Accountability in the U.S. House of Representatives
Authors: Bovitz Gregory L. , Carson Jamie L.
Published: January 2007

While past research has offered some initial evidence linking patterns of position-taking behavior with incumbents’ electoral fortunes, we are left without a comprehensive study that informs us whether individual roll-call votes can be electorally consequential and lends insight into the conditions under which position-taking on roll calls may yield electoral implications. This article takes a step toward filling that void by examining the electoral implications of hundreds of House roll calls since the early 1970s. We find that, after controlling for the usual factors, a wide range of individual roll-call decisions have significant effects on incumbents’ electoral margins. We also find that the extent to which a particular roll call is controversial, salient, and a catalyst for intra-party disagreement affects whether it has electoral implications. In sum, our analysis addresses longstanding questions regarding how and when legislators are rewarded or punished at the polls for their behavior in Congress.
Cognitive Style and Political Learning in the 2000 U.S. Presidential Campaign
Authors: Holbrook Thomas M.
Published: January 2007

This article explores the impact of cognitive style, as measured by need to evaluate and need for cognition, on information acquisition during the 2000 U.S. presidential campaign. Using data from the 2000 National Election Study I show that both constructs are related to measures of candidate information, i.e., correct ideological placement, correct policy placement, and number of candidate articulations; but that need to evaluate has a much stronger and more consistent effect than does need for cognition. The implications of these findings are discussed.
The Diversity of State Interest Group Systems
Authors: Gray Virginia , Lowery David
Published: January 2007

As part of a larger effort to develop an independent system-level theory of interest groups, we explore the system-level trait of interest group diversity. A model of state interest group diversity is developed and tested with state data from the early 1980s. We find that interest group diversity is related to economic diversity and economic size, whereas its relation to wealth and to the number of interest groups contrasts sharply with much of our conventional wisdom about state interest groups. We discuss the implications of these findings for understanding state interest group politics and outline how they contribute to a larger research program on state interest group systems.
Protest Cycles and Political Process: American Peace Movements in the Nuclear Age
Authors: Meyer David S.
Published: January 2007

Since the dawn of the nuclear age small groups of activists have consistently protested both the content of United States national security policy, and the process by which it is made. Only occasionally, however, has concern about nuclear weapons spread beyond these relatively marginal groups, generated substantial public support, and reached mainstream political institutions. In this paper, I use histories of peace protest and analyses of the inside of these social movements and theoretical work on protest cycles to explain cycles of movement engagement and quiescence in terms of their relation to external political context, or the "structure of political opportunity." I begin with a brief review of the relevant literature on the origins of movements, noting parallels in the study of interest groups. Building on recent literature on political opportunity structure, I suggest a theoretical framework for understanding the lifecycle of a social movement that emphasizes the interaction between activist choices and political context, proposing a six-stage process through which challenging movements develop. Using this theoretical framework I examine the four cases of relatively broad antinuclear weapons mobilization in postwar America. I conclude with a discussion of movement cycles and their relation to political alignment, public policy, and institutional politics.