bluuebunny/crossref_metadata_2025_split huggingface dataset:
Establishment of a kinetic model for the intramolecular catalyzed hydrolysis of [18F]‐benzylfluoride containing amino acid analogues by linking experimental and DFT studies
Authors: Kersemans Ken , Sablon Nick , Geerlings Paul , Mertens John 
Published: May 2012

AbstractIn an earlier publication, we suggested that the faster radiodefluorination kinetics of no‐carrier‐added (S)‐3‐(2‐[18F]fluoromethyl‐phenyl)‐2‐amino‐propionic acid (2‐[18F]FMLP), as compared to 4‐[18F]‐fluoromethyl‐l‐phenylalanine (4‐[18F]FMLP), was caused by an intramolecular interaction between the CH2F group on the 2‐position of the phenyl ring and the ammonium group of the amino acid. As the presence of nonradioactive (S)‐3‐(2‐fluoromethyl‐phenyl)‐2‐amino‐propionic acid (2FMLP) in a concentration up from 10−6 mol/L reduces considerably the defluorination rate due to the formation of dimers, conventional experimental methods, like spectroscopy, cannot be performed for the study of the hydrolysis in no‐carrier‐added conditions occurring at a concentration range of about 5.0 10−10 mol/L. In the present study, we aim to provide a proof that supports aforementioned hypothesis as well as to establish a kinetic model and to put forward accompanying rate equations for this hydrolysis reaction by combining ab initio quantum chemical calculations and kinetic data. The calculations of the optimized geometries and the corresponding energies of the reactants involved in the hydrolysis of 2‐[18F]FMLP and 4‐[18F]FMLP were performed at the DFT[B3LYP/6‐31++G**] level of theory. Interpretation of these data reveals that in 2‐[18F]FMLP three intramolecular hydrogen bond interactions can be identified that are not present in 4‐[18F]FMLP. The most important interaction is the one between the amino acid ammonium group and the benzylic fluorine atom, rendering the rupture of the CF bond much more favorable. These findings align with the experimental data and enabled us to put forward the rate expressions that define the unexpected pseudo–zero‐order defluorination reaction of 2‐[18F]FMLP at neutral pH. This study also proves that in the development of [18F]‐benzylfluoride containing tracers present‐day quantum chemical calculations are capable of predicting intramolecular interactions, affecting their reactivity toward hydrolysis at the no‐carrier‐added level. © 2012 Wiley Periodicals, Inc. Int J Chem Kinet 44: 705–711, 2012
On Polarizing Outranking Relations with Large Performance Differences
Authors: Bisdorff Raymond 
Published: May 2012

ABSTRACTWe introduce a bipolarly extended veto principle—a positive, as well as negative, large performance differences polarization—which allows us to extend the definition of the classical outranking relation in such a way that the identity between its asymmetric part and its codual relation is preserved. Copyright © 2012 John Wiley & Sons, Ltd.
Evaluation of the reliability of high concentrator GaAs solar cells by means of temperature accelerated aging tests
Authors: Núñez N. , González J. R. , Vázquez M. , Algora C. , Espinet P. 
Published: May 2012

ABSTRACTEvaluating the reliability, warranty period, and power degradation of high concentration solar cells is crucial to introducing this new technology to the market. The reliability of high concentration GaAs solar cells, as measured in temperature accelerated life tests, is described in this paper. GaAs cells were tested under high thermal accelerated conditions that emulated operation under 700 or 1050 suns over a period exceeding 10 000 h. Progressive power degradation was observed, although no catastrophic failures occurred. An Arrhenius activation energy of 1.02 eV was determined from these tests. The solar cell reliability [R(t)] under working conditions of 65°C was evaluated for different failure limits (1–10% power loss). From this reliability function, the mean time to failure and the warranty time were evaluated. Solar cell temperature appeared to be the primary determinant of reliability and warranty period, with concentration being the secondary determinant. A 30‐year warranty for these 1 mm2‐sized GaAs cells (manufactured according to a light emitting diode‐like approach) may be offered for both cell concentrations (700 and 1050 suns) if the solar cell is operated at a working temperature of 65°C. Copyright © 2012 John Wiley & Sons, Ltd.
An Ill‐posed inverse problem in enzymatic kinetics: Jack‐Bean urease denaturation by an anionic surfactant
Authors: Borges E. , Menezes D. C. , Braga J. P. 
Published: May 2012

AbstractA neural network procedure is applied to solve an ill‐posed inverse problem in chemical kinetics relevant to chemical and biological areas; calculation of rate constants for the jack‐bean urease denaturation by an anionic surfactant agent from experimental enzyme concentrations. The efficiency of the algorithm proposed is compared with the Simplex and the Levenberg–Marquardt techniques, often used in nonlinear regression methods to solve this kind of kinetics problem. The neural network approach is numerically stable and robust with respect to different initial guesses for the rate constants and noises in experimental data. © 2012 Wiley Periodicals, Inc.
The molecular structure of AgBr2 and AgBr2+. A benchmark CASSCF, CASPT2, and averaged coupled pair functional study
Authors: Ramírez‐Solís A. 
Published: May 2012

AbstractThe ground states of AgBr2 and AgBr2+ have been predicted to be 2B2 and 1A1 bent structures (θ = 67° and θ = 47°, respectively) using complete active space self‐consistent field (CASSCF) and multireference second order perturbation theory (J. Chem. Phys., 1999, 111, 8925). Because CuF2, CuCl2, and AgCl2 are known to be linear, the ground states of AgBr2 and AgBr2+ have been studied through benchmark ab initio CASSCF(21,15), multireference second‐order perturbation theory and averaged coupled pair functional calculations using very large and especially developed valence basis sets. The bent nature of the ground state of the AgBr2+ ion is confirmed, but for AgBr2 the absolute minimum of the ground state is found to be 2Πg in the linear centrosymmetric structure with the present large optimized basis sets at all levels of theory. Also, a significant Ag‐Br bond length reduction was obtained for the cation with respect to the previous value. These results show the crucial role played by the quality of the valence atomic basis sets for this type of transition metal molecules on key properties such as the equilibrium geometry. New equilibrium geometries, vibrational frequencies and ionization potentials are presented. © 2012 Wiley Periodicals, Inc.
Developing a framework for the use of discount rates in actuarial work ‐ Abstract of the Edinburgh discussion
Authors: Cowling Charles 
Published: May 2012

This abstract relates to the following paper:CowlingC.A., FranklandR., HailsR.T.G., KempM.H.D., LosebyR.L., OrrJ.B., and SmithA.D.Developing a framework for the use of discount rates in actuarial work. British Actuarial Journal, doi:10.1017/S1357321712000013
Second International comparative study of mortality tables for pension fund retirees
Authors: Sithole T. Z. , Haberman S. , Verrall R. J. 
Published: May 2012

AbstractThis paper contains an update to the first international comparative study of mortality tables carried out in 2006. It examines the mortality assumptions used in the valuation of pension liabilities in a number of different countries. The results are considered in relation to the underlying population mortality rates, in order to isolate the strength of the mortality assumptions being applied. It is found that there is evidence of a lack of consistency between countries, and that this has not changed since the previous study.
A Bayesian smoothing spline method for mortality modelling
Authors: Luoma Arto , Puustelli Anne , Koskinen Lasse 
Published: May 2012

AbstractWe propose a new method for two-dimensional mortality modelling. Our approach smoothes the data set in the dimensions of cohort and age using Bayesian smoothing splines. The method allows the data set to be imbalanced, since more recent cohorts have fewer observations. We suggest an initial model for observed death rates, and an improved model which deals with the numbers of deaths directly. Unobserved death rates are estimated by smoothing the data with a suitable prior distribution. To assess the fit and plausibility of our models we perform model checks by introducing appropriate test quantities. We show that our final model fulfils nearly all requirements set for a good mortality model.
Dissolved platinum in major rivers of East Asia: Implications for the oceanic budget
Authors: Soyol‐Erdene Tseren‐Ochir , Huh Youngsook 
Published: May 2012

Dissolved platinum concentrations of eleven large pristine river systems in East Asia (∼200 samples) were determined to better constrain the oceanic platinum budget. Most samples had concentrations less than 1.4 pM; relatively high concentrations up to 5.8 pM were measured in only approximately 6% of the samples. The median Pt concentrations of the individual river systems had only a small range, from 0.18 pM (Duman) to 0.63 pM (Huang He), and the difference in Pt yield mainly resulted from the difference in runoff. The rivers draining the eastern Tibetan Plateau – the Salween, Mekong, Chang Jiang (Yangtze), Hong (Red), and Huang He (Yellow) – had higher Pt yield than the rivers of the Russian Far East – the Amur, Lena, Yana, Indigirka, and Kolyma. If the discharge‐weighted mean Pt concentration of our samples (0.36 pM) is extrapolated globally, the estimated riverine flux of dissolved Pt to the ocean is 13 × 103 mol y−1. Based on this riverine flux, the estimated oceanic residence time of Pt is 24 ± 10 kyrs. A 50% release and 50% uptake of Pt in estuaries would modify this to 16 kyrs and 45 kyrs, respectively.
Superresolution imaging of HIV in infected cells with FlAsH-PALM
Authors: Lelek Mickaël , Di Nunzio Francesca , Henriques Ricardo , Charneau Pierre , Arhel Nathalie , Zimmer Christophe 
Published: May 2012

Imaging protein assemblies at molecular resolution without affecting biological function is a long-standing goal. The diffraction-limited resolution of conventional light microscopy (∼200–300 nm) has been overcome by recent superresolution (SR) methods including techniques based on accurate localization of molecules exhibiting stochastic fluorescence; however, SR methods still suffer important restrictions inherent to the protein labeling strategies. Antibody labels are encumbered by variable specificity, limited commercial availability and affinity, and are mostly restricted to fixed cells. Fluorescent protein fusions, though compatible with live cell imaging, substantially increase protein size and can interfere with their biological activity. We demonstrate SR imaging of proteins tagged with small tetracysteine motifs and the fluorescein arsenical helix binder (FlAsH-PALM). We applied FlAsH-PALM to image the integrase enzyme (IN) of HIV in fixed and living cells under experimental conditions that fully preserved HIV infectivity. The obtained resolution (∼30 nm) allowed us to characterize the distribution of IN within virions and intracellular complexes and to distinguish different HIV structural populations based on their morphology. We could thus discriminate ∼100 nm long mature conical cores from immature Gag shells and observe that in infected cells cytoplasmic (but not nuclear) IN complexes display a morphology similar to the conical capsid. Together with the presence of capsid proteins, our data suggest that cytoplasmic IN is largely present in intact capsids and that these can be found deep within the cytoplasm. FlAsH-PALM opens the door to in vivo SR studies of microbial complexes within host cells and may help achieve truly molecular resolution.
Behavioural compensation reduces energy expenditure during migration hyperphagia in a large bird
Authors: Guillemette Magella , Richman Samantha E. , Portugal Steven J. , Butler Patrick J. 
Published: May 2012

Summary1. Bird migration is often seen as the summit of animal performance. Because higher foraging effort associated with fuelling and increased flight activity should generate maximum level of energy turnover, we expect the migratory process to be constrained by energy, whether it is energy expenditure or energy intake.2. We used implanted data loggers to continuously monitor foraging effort, flight activity and heart rate (as a proxy for rate of energy expenditure), in a wild migratory sea duck before and after moult migration to test the energy budget limitation hypothesis.3. We show that despite the fact that departing birds forage at three times the level observed during post‐migration, daily energy expenditure (DEE) remains the same when periods before and after migration are compared.4. In an attempt to determine how the birds achieve such a feat, we compared heart rate when active (feeding and flying) for the periods before and after migration and found no significant difference for feeding and flight heart rate. However, heart rate during periods of inactivity was significantly lower during fuelling which together with a reduced time spent flying completely counteracted the observed high energy costs of foraging.5. The time spent active represented a tiny proportion (8–20%) of the 24‐h time budget suggesting that energy minimization and an optimization process may be at work here, confounding any apparent support for the energy budget limitation hypothesis. We thus concluded that similar DEE before and after migration could be owing to the bird’s inability to increase energy expenditure over a certain limit or to the survival costs associated with a certain level of physical exertion. Nevertheless, our results indicate that behavioural, and possibly physiological, compensation may be used as a mechanism to reduce the overall energy cost of fuelling in migrating birds.
Persistence of vigilance and flight response behaviour in wild reindeer with varying domestic ancestry
Authors: REIMERS E. , RØED K. H. , COLMAN J. E. 
Published: May 2012

AbstractKnowledge about changes in behavioural traits related to wildness and tameness is for most mammals lacking, despite the increased trend of using domestic stock to re‐establish wild populations into historical ranges. To test for persistence of behavioural traits of wild reindeer (Rangifer tarandus L.) exposed to hunting, we sampled DNA, vigilance and flight responses in wild reindeer herds with varying domestic ancestry. Analyses of 14 DNA microsatellite loci revealed a dichotomous main genetic structure reflecting their native origin, with the Rondane reindeer genetically different from the others and with least differentiation towards the Hardangervidda reindeer. The genetic clustering of the reindeer in Norefjell‐Reinsjøfjell, Ottadalen and Forollhogna, together with domestic reindeer, supports a predominant domestic origin of these herds. Despite extensive hunting in all herds, the behavioural measures indicate increasing vigilance, alert and flight responses with increasing genetic dissimilarity with domestic herds. Vigilance frequency and time spent vigilant were higher in Rondane compared to Hardangervidda, which again were higher than herds with a domestic origin. We conclude that previous domestication has preserved a hard wired behavioural trait in some reindeer herds exhibiting less fright responses towards humans that extensive hunting has, but only slightly, altered. This brings novel and relevant knowledge to discussions about genetic diversity of wildlife in general and wild reindeer herds in Norway in specific.
Differential modulations of ipsilateral and contralateral beta (de)synchronization during unimanual force production
Authors: van Wijk B. C. M. , Beek P. J. , Daffertshofer A. 
Published: May 2012

AbstractUnilateral movement is usually accompanied by ipsilateral activity in the primary motor cortex (M1). It is still largely unclear whether this activity reflects interhemispheric ‘cross‐talk’ of contralateral M1 that facilitates movement, or results from processes that inhibit motor output. We investigated the role of beta power in ipsilateral M1 during unimanual force production. Significant ipsilateral beta desynchronization occurred during continuous dynamic but not during static force production. Moreover, event‐related time–frequency analysis revealed bilateral desynchronization patterns, whereas post‐movement synchronization was confined to the contralateral hemisphere. Our findings indicate that ipsilateral activation is not merely the result of interhemispheric cross‐talk but involves additional processes. Given observations of differential blood oxygen level‐dependent responses in ipsilateral and contralateral M1, and the correlation between beta desynchronization and the firing rate of pyramidal tract neurons in contralateral M1 during movement, we speculate that beta desynchronization in contra‐ and ipsilateral M1 arises from distinct neural activation patterns.
Screening by pulse CO‐oximetry for environmental tobacco smoke exposure in preanesthetic children
Authors: Cardwell Kathryn , Pan Zhaoxing , Boucher Rebecca , Zuk Jeannie , Friesen Robert H. 
Published: May 2012

SummaryObjective:  The purpose of this study was to evaluate the ability of multiple wavelength pulse CO‐oximetry (SpCO) to screen for environmental tobacco smoke (ETS) exposure in children.Background:  Exposure to ETS is associated with an increased risk of perioperative respiratory complications in children. It is often difficult to obtain an accurate history for ETS exposure, so a preoperative screening tool is desirable. Carbon monoxide is a measurable product of tobacco combustion. Multiple wavelength pulse CO‐oximetry is a recently developed point‐of‐care monitor.Methods:  Following IRB approval and parental consent, 220 children aged 1–16 years having outpatient surgical procedures were enrolled. SpCO was measured preoperatively three times with the Radical‐7 Rainbow SET CO‐oximeter (Masimo, Irvine, CA, USA). Immediately following induction of anesthesia, a blood sample for laboratory measurement of carboxyhemoglobin (COHb) and serum cotinine was obtained. Regression analysis determined the correlation of SpCO with serum cotinine values. Receiver operator characteristic (ROC) curves analyzed the discriminating ability of SpCO or COHb to predict ETS exposure based on cotinine cutoff values known to be present in children exposed to ETS. Agreement of SpCO and COHb values was assessed using Bland–Altman plots.Results:  SpCO did not correlate with cotinine (R2 = 0.005). Both SpCO and COHb had poor discriminating ability for ETS exposure (area under the ROC curve = 0.606 and 0.562, respectively). SpCO values had poor agreement with COHb values.Conclusions:  The point‐of‐care multiple wavelength pulse CO‐oximeter does not appear to be a useful preoperative screening tool for ETS exposure in children.
Hemodynamic changes during spinal anesthesia in premature infants with congenital heart disease undergoing inguinal hernia correction
Authors: Shenkman Ze’ev , Johnson Victor M. , Zurakowski David , Arnon Shmuel , Sethna Navil F. 
Published: May 2012

SummaryIntroduction:  There are conflicting reports on the effects of spinal anesthesia (SA) on hemodynamics. Data on the hemodynamic effects of SA in infants with congenital heart disease (CHD) are limited.Methods:  We reviewed our experience with 44 unsupplemented SA with 1 mg·kg−1 of either hyperbaric tetracaine or bupivacaine in premature and former premature infants with noncyanotic CHD. Hemodynamics and oxyhemoglobin saturation (SpO2) were assessed. Neither preoperative fluid boluses nor atropine was administered to any of the infants.Results:  There was no significant change in systolic, diastolic, or mean blood pressures from pre‐SA induction compared with end of surgery. Heart rate showed a small but systematic decline (mean change of 10 beats per minute, P < 0.01) but was within the normative range values for age. There was a small, but clinically insignificant increase in SpO2 across the time course. Intraoperatively, two infants developed transient apneic spells. No infant developed postoperative apnea, oxygen desaturation, or bradycardia.Conclusions:  The data suggest that SA with 1 mg·kg−1 of either hyperbaric tetracaine or bupivacaine can be used safely as the sole anesthetic for inguinal hernia repair in infants with noncyanotic CHD even when fluid restricted and apparently causes minimal respiratory complications in these infants.
Depression and diabetes in India: perspectives and recommendations
Authors: Mendenhall E. , Narayanan G. , Prabhakaran D. 
Published: May 2012

Diabet. Med. 29, e308–e311 (2012)AbstractAs diabetes prevalence shifts from affluent to lower‐income groups in India, focus on depression in diabetes will become essential. This paper describes four perspectives through which depression and diabetes should be understood in the Indian context. We consider (1) how rapid socio‐economic and demographic changes contribute to increased co‐occurring diabetes and depression; (2) how social, cultural and economic factors in the Indian context contribute to depression and therefore play an important role in diabetes care; (3) biological and behavioural pathways between depression and diabetes; and (4) the role of health systems in depression, diabetes and their overlap. We conclude with recommendations for future research and policy on this topic in India.
Adaptive Compression of Texture Pyramids
Authors: Andujar C. 
Published: May 2012

AbstractHigh‐quality texture minification techniques, including trilinear and anisotropic filtering, require texture data to be arranged into a collection of pre‐filtered texture maps called mipmaps. In this paper, we present a compression scheme for mipmapped textures which achieves much higher quality than current native schemes by exploiting image coherence across mipmap levels. The basic idea is to use a high‐quality native compressed format for the upper levels of the mipmap pyramid (to retain efficient minification filtering) together with a novel compact representation of the detail provided by the highest‐resolution mipmap. Key elements of our approach include delta‐encoding of the luminance signal, efficient encoding of coherent regions through texel runs following a Hilbert scan, a scheme for run encoding supporting fast random‐access, and a predictive approach for encoding indices of variable‐length blocks. We show that our scheme clearly outperforms native 6:1 compressed texture formats in terms of image quality while still providing real‐time rendering of trilinearly filtered textures.