bluuebunny/crossref_metadata_2025_split huggingface dataset:
QSAR Analysis of 2,3‐Diaryl Benzopyrans/Pyrans as Selective COX‐2 Inhibitors Based on Semiempirical AM1 Calculations
Authors: Prasanna Sivaprakasam , Manivannan Elangovan , Chaturvedi Subash Chandra 
Published: November 2004

AbstractQuantitative structure‐activity relationship (QSAR) analysis was performed on a combined series of 2,3 diaryl benzopyrans and pyrans for their cyclooxygenase‐2 (COX‐2) inhibition. QSAR investigations based on semiempirical, Austin Model‐1 (AM1) calculations reveal that electronic and hydophobic interactions are primarily responsible for COX‐2 enzyme‐ligand interaction. The derived QSAR model aided by residual analysis demonstrated that the COX‐2 inhibitory activity is highly correlated with the electronic descriptors, lowest unoccupied molecular orbital (ELUMO), Dipole‐Z and hydrophobicity of the molecules. The conclusion can be drawn that more hydrophobic, electron‐withdrawing substituents at 3rd aromatic ring of the lead structure improves activity. The lesser the Z component the ligand has, the more correct its orientation towards the COX‐2 binding site. The derived QSAR model shows good internal (exemplified through leave one out‐q2=0.786) and external (r$\rm{ {_{pred}^{2}}}$=0.5737) predictive ability for a test set and can be used in designing better selective COX‐2 inhibitors among these congeners in future.
Prediction of Carbonic Anhydrase Activation by Tri‐/Tetrasubstituted‐pyridinium‐azole Compounds: A Computational Approach Using Novel Topochemical Descriptor
Authors: Bajaj Sanjay , Sambi S. S. , Madan A. K. 
Published: November 2004

AbstractSee original QSAR Comb. Sci. 2004, 23, 506–514
Slater's nonlocal exchange potential and beyond
Authors: Howard I. A. , March N. H. 
Published: November 2004

AbstractThe local density approximation (LDA) to the exchange potential Vx(r), namely the ρ1/3 electron gas form, was already transcended in Slater's 1951 paper. Here, using Dirac's 1930 form for the exchange energy density ϵx(r), the Slater (Sl) nonlocal exchange potential V(r) is defined by 2ϵx(r)/ρ(r). In spherical atomic ions, say the Be or Ne‐like series, this form V(r) already has the correct behavior in both r → 0 and r → ∞ limits when known properties of the exchange energy density ϵx(r) and the ground‐state electron density ρ(r) are invoked. As examples, some emphasis will first be given to the use of the so‐called 1/Z expansion in such spherical atomic ions, for which analytic results can be obtained for both ϵx(r) and ρ(r) as the atomic number Z becomes large. The usefulness of the 1/Z expansion is directly demonstrated for the U atomic ion with 18 electrons by comparison with the optimized effective potential prediction. A rather general integral equation for the exchange potential is then proposed. Finally, without appeal to large Z, two‐level systems are considered, with specific reference to the Be atom and to the LiH molecule. In all cases treated, the Slater potential V(r) is a valuable starting point, even though it needs appreciable quantitative corrections reflecting directly atomic shell structure. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
UV laser ablation of GdCa4O(BO3)3 (GdCOB) investigated by Fourier transform ion cyclotron resonance mass spectrometry
Authors: Chéty‐Gimondo Rachel , Aubriet Frédéric , Millon Eric , Muller J.‐F. 
Published: November 2004

AbstractThe ions generated by laser ablation (LA) of calcium and gadolinium oxoborate GdCa4O(BO3)3 (GdCOB) were investigated by Fourier transform ion cyclotron resonance mass spectrometry (FTICRMS), a powerful tool for the characterization of ionic species produced by laser interaction with solid material. In order to better understand the matter transfer and the mechanism of thin film growth by pulsed‐laser deposition (PLD), cationic and anionic clusters generated by UV laser ablation of GdCOB bulk material were studied. Laser ablation of GdCOB leads to the formation of various cluster ions which result from association of CaO, BO and B2O3 building blocks (BB) with different charge carriers (CC): H+, BO+, GdO+ in positive ion mode, and BO, OK−, OH−, Cl−, WO in negative ion mode. LA‐FTICRMS investigations allow us to assign a valence state to each metallic atom included in each BB. A +II chemical state may be associated with calcium and +II and +III ones to boron. UV laser ablation of GdCOB therefore induces reduction processes of boron species in the gas phase. The oxygen reactive atmosphere used during PLD experiments allows the growth of stoichiometric thin films by fixation of oxygen on the ablated species. Copyright © 2004 John Wiley & Sons, Ltd.
Migratory patterns and return to the catch site of adult brown trout (Salmo trutta L.) in a regulated river
Authors: Arnekleiv Jo Vegar , Rønning Lars 
Published: November 2004

AbstractThe spawning migration and local homing of adult brown trout was analysed using radio telemetry in a regulated river in central Norway. Twenty‐eight large (37–64 cm) brown trout (Salmo trutta L.) were tracked before, during and after spawning in the River Nea, a watercourse with several obstructions, including an outlet tunnel from a power station and a regulated stretch (26 km) with 45 weirs.Two major patterns of spawning migration were found: (1) about half (n = 16; 57%) of the trout moved very little and remained in the deeper pools of the river from June until November; (2) about half (n = 12; 43%) of the trout migrated relatively long distances (12.5–28 km) up the river prior to the spawning period where they stayed in the outlets of small tributaries, or in rapids on the main river during the spawning period. We assume that these trout belong to a population of lake‐run migratory trout using the River Nea for spawning.There was no significant difference in body length of migratory and stationary brown trout and no significant difference in total distance moved by migratory males (30.5 km, n = 6) and females (20.5 km, n = 6, p > 0.05). Among migratory trout, we found no correlation between body length and migrated distance. Of the 12 migratory trout, nine undertook fast upward migration in periods of high water flow (> 100 m3/s). They passed the outlet tunnel from the power station and negotiated two to 35 weirs before reaching their main reproduction areas. Three trout crossed several weirs when the discharge was low (10–40 m3/s). When there was low discharge, fish remained at the outlet tunnel for up to four weeks and showed a high level of activity. Postspawning downstream migration started between 25 September and 25 October. Most migratory trout (n = 9) wintered in pools on the lower part of the river or in weir basins; only two trout descended to the lake (Selbusjøen) in late autumn. Copyright © 2004 John Wiley & Sons, Ltd.
Case‐sibling gene‐association studies for diseases with variable age at onset
Authors: Kraft Peter , Thomas Duncan C. 
Published: November 2004

AbstractStudies which compare cases to disease‐free siblings are useful for assessing association between a genetic locus and a phenotypic trait, as they eliminate the possibility of confounding by population stratification. Many analytic methods for such family‐based studies are based on a binary disease model. However, complex diseases have variable age at onset. Consequently, binary‐outcome methods can be inefficient or biased. We review methods for analysing censored age‐at‐onset data from family studies, including stratified Cox regression and genotype‐decomposition regression, an unstratified procedure which regresses age‐at‐onset on between‐ and within‐family genotype components. We also introduce a retrospective likelihood for censored age‐at‐onset data, which requires an external estimate of the baseline hazard. Stratified Cox regression does not use controls who have not attained the age of their case sibling(s), potentially leading to a loss of efficiency. Both genotype‐decomposition regression and the retrospective likelihood use these younger controls. We assess the performance of these methods via simulation studies. Stratified Cox regression and the retrospective likelihood have appropriate type I error rates in almost all situations studied; genotype‐decomposition regression is often anti‐conservative. Away from the null, confidence intervals for the relative risk derived from stratified Cox regression are anti‐conservative when the disease is rare and case‐rich families are sampled. The retrospective likelihood is more efficient than stratified Cox regression and its confidence intervals have correct coverage when the disease is rare or the estimate of the baseline hazard is reasonably accurate. These results suggest that when estimating genotype relative risks is the principal analytic goal, stratified Cox regression is appropriate as long as the disease is common; when the disease is rare, the retrospective likelihood may be more appropriate. Copyright © 2004 John Wiley & Sons, Ltd.
Ordered multiple‐class ROC analysis with continuous measurements
Authors: Nakas Christos T. , Yiannoutsos Constantin T. 
Published: November 2004

AbstractReceiver operating characteristic (ROC) curves have been useful in two‐group classification problems. In three‐ and multiple‐class diagnostic problems, an ROC surface or hyper‐surface can be constructed. The volume under these surfaces can be used for inference using bootstrap techniques or U‐statistics theory. In this article, ROC surfaces and hyper‐surfaces are defined and their behaviour and utility in multi‐group classification problems is investigated. The formulation of the problem is equivalent to what has previously been proposed in the general multi‐category classification problem but the definition of ROC surfaces here is less complex and addresses directly the narrower problem of ordered categories in the three‐class and, by extension, the multi‐class problem applied to continuous and ordinal data. Non‐parametric manipulation of both continuous and discrete test data and comparison between two diagnostic tests applied to the same subjects are considered. A three‐group classification example in the context of HIV neurological disease is presented and the results are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
The interpoint distance distribution as a descriptor of point patterns, with an application to spatial disease clustering
Authors: Bonetti Marco , Pagano Marcello 
Published: November 2004

AbstractThe topic of this paper is the distribution of the distance between two points distributed independently in space. We illustrate the use of this interpoint distance distribution to describe the characteristics of a set of points within some fixed region. The properties of its sample version, and thus the inference about this function, are discussed both in the discrete and in the continuous setting. We illustrate its use in the detection of spatial clustering by application to a well‐known leukaemia data set, and report on the results of a simulation experiment designed to study the power characteristics of the methods within that study region and in an artificial homogenous setting. Copyright © 2004 John Wiley & Sons, Ltd.
Chronic disease prevention: public health potential and research needs
Authors: Prentice Ross L. 
Published: November 2004

AbstractThis paper, arising out of an event to honour the statistical and scientific contributions of Professor Peter Armitage, is concerned with research strategies and needs for chronic disease prevention. A few highlights from recent intervention trials for the prevention of cancer, cardiovascular disease, fractures and diabetes is provided, along with a discussion of some settings where intervention trial results seem discrepant with a body of preceding observational data. This background is used to identify research strategies and infrastructure needs for moving this vitally important research area forward, for both chemoprevention and lifestyle modification interventions. Copyright © 2004 John Wiley & Sons, Ltd.
The Effects of Plasticizers Containing Amide Groups on the Properties of Thermoplastic Starch
Authors: Ma Xiaofei , Yu Jiugao 
Published: November 2004

AbstractSeveral amide groups‐containing plasticizers for thermoplastic starch (TPS), such as formamide, acetamide, and urea, were studied in this paper with glycerol as reference. The hydrogen bond interaction between starch and plasticizers in TPS was tested by Fourier transform infrared (FT‐IR) spectroscopy. Both the oxygen of the C‐O‐H group and the oxygen of the C‐O‐C group in starch could form hydrogen bonds with these plasticizers. The order of the hydrogen bond‐forming abilities is as follows: urea > formamide > acetamide > polyols. The retrogradation of formamide‐plasticized TPS (FPTPS), acetamide‐plasticized TPS (APTPS) and urea‐plasticized TPS (UPTPS) was investigated at three levels of relative humidity (RH=0, 50 and 100%) using X‐ray diffractometry. Urea and formamide could effectively improve the resistance of TPS towards retrogradation. The studied mechanical properties demonstrated that FPTPS had a good breaking strain but poor breaking stress, while UPTPS had opposite characteristics. The properties of TPS mainly relied on the hydrogen bond‐forming abilities between plasticizers and the starch matrix. On the other hand, the water resistance of TPS mainly depended on the plasticizer. The higher the water absorption of the plasticizer was, the better was the water resistance of the TPS.
Ligand–ligand redox interaction through some metal‐cluster units
Authors: Sasaki Yoichi , Abe Masaaki 
Published: November 2004

AbstractThe ligand–ligand redox interaction separated by di‐, tri‐, and hexanuclear cluster units is discussed in terms of the splitting of the redox waves (ΔE(L)) and the comproportionation constants (Kcom(L)) of the ligand‐based mixed valence state. Although two redox‐active monodentate ligands in the mononuclear ruthenium(II) complexes (either cis or trans configurations) do not show appreciable splitting in their reduction waves, interestingly those separated by giant triruthenium and hexarhenium cluster units clearly show splitting. The molecular orbital considerations in the literature suggest that these units possess some π‐type molecular orbitals composed of metal dπ and possibly ligand pπ orbitals. Absence of the redox interactions in oxo‐bridged diruthenium(II) and oxo‐centered trirhodium(III) complexes where such π molecular orbitals (including an antibonding one) are fully occupied, indicates the importance of empty π* orbitals for the ligand redox communication. © 2004 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 4: 279–290; 2004: Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/tcr.20021
Measuring engagement of the fetal head: validity and reproducibility of a new ultrasound technique
Authors: Dietz H. P. , Lanzarone V. 
Published: November 2004

AbstractObjectiveFetal head engagement can be assessed by translabial ultrasound and has been shown to be predictive of delivery mode. We attempted to validate the technique by comparing ultrasound with abdominal and vaginal palpation. Reproducibility was tested in a blinded test–retest series.MethodsIn a prospective clinical study, 139 nulliparous women between 35 + 3 and 40 + 4 weeks' gestation were assessed by translabial ultrasound, abdominal palpation of the fetal head (n = 139) and vaginal examination (n = 112). Ultrasound was performed using two methods, with the symphysis pubis as reference. A test–retest series was performed in 90 women.ResultsUltrasound of head engagement correlated strongly with abdominal palpation, full Bishop scores and vaginal assessment (all P < 0.001 for Kendall's tau‐b). Intraclass correlation coefficients (n = 90) for the two methods were 0.75 and 0.92, signifying excellent interobserver agreement. Reproducibility was higher for the method using the central symphyseal axis as reference.ConclusionQuantitation of head engagement by translabial ultrasound is highly reproducible and correlates strongly with clinical measures of head engagement. We are now undertaking a prospective study to assess the predictive value of this new parameter for intrapartum events. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
The short‐term effect of nifedipine tocolysis on placental, fetal cerebral and atrioventricular Doppler waveforms
Authors: Guclu S. , Saygili U. , Dogan E. , Demir N. , Baschat A. A. 
Published: November 2004

AbstractObjectiveTo evaluate the effect of nifedipine on placental and fetal middle cerebral and atrioventricular Doppler waveforms.MethodsDoppler waveforms of uterine (UtA), umbilical (UA) and middle cerebral (MCA) arteries and both atrioventricular valves were measured from 21 pregnant women/fetuses prior to and during nifedipine therapy for preterm labor. Maternal and fetal heart rates (FHR), maternal systolic and diastolic blood pressure, the Doppler pulsatility index and systolic/diastolic ratio of the UtA, UA and MCA were measured. The total time velocity integrals (TVI) of tricuspid and mitral valves and their E‐wave/A‐wave (E/A) TVI ratios were measured. Wilcoxon signed pairs test was used to compare the differences in Doppler parameters before and at 3 h after nifedipine loading up to a maximum dose of 40 mg.ResultsFetal arterial and UtA Doppler parameters were not different before and after nifedipine therapy. Blood flow across the atrioventricular valves and the TVI were equally unaffected by nifedipine. The TVI × FHR product was also unchanged following nifedipine therapy.ConclusionsIn women with otherwise uncomplicated pregnancies, nifedipine loading and tocolysis are generally well tolerated by the mother. Placental and fetal cerebral arterial blood flow, fetal systolic and diastolic cardiac function and downstream distribution of fetal cardiac output are unaffected by nifedipine loading. These results apply to women with unchanged vital parameters. Further studies are necessary to show long‐term effects of nifedipine therapy and may help to refine choice of tocolytic agents. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Evaluation of interference due to UWB hot spot on fixed wireless access systems
Authors: Giuliano Romeo , Guidoni Gianluca , Habib Ibrahim , Mazzenga Franco 
Published: November 2004

AbstractUltra Wide Bandwidth (UWB) techniques are getting an increased importance due to their many features such as high bit rates availability, low power consumption and location capabilities. UWB technology enables the development of advanced wireless local area networks providing integrated multimedia services to nomadic users over hot‐spot areas. The assessment of the possible interference caused by UWB devices on already existing narrowband and wideband systems is fundamental to ensure not‐conflicting coexistence and, therefore, the acceptance of UWB technology worldwide. In this paper we analyze coexistence between an indoor UWB system and an outdoor fixed wireless access (FWA) system operating in the 3.5–5.0 GHz band. We consider a realistic UWB master/slave system architecture using pulse amplitude modulated spread spectrum signals for multiple access and we evaluate the UWB system interfering power in the FWA band accounting for the UWB power spectrum shape. Both upstream and downstream communication directions are analyzed. We show through computer simulation, that in many practical cases UWB system can coexist with FWA without causing any dangerous interference. Copyright © 2004 John Wiley & Sons, Ltd.
Uncertainty and traceability in alloy analysis by borate fusion and XRF
Authors: Sieber John R. , Yu Lee L. , Marlow Anthony F. , Butler Theresa A. 
Published: November 2004

AbstractOwing to the increasing demand for compliance with quality system standards, analytical laboratories may need to demonstrate the traceability of their results to the International System of Units (SI) or to the values of a certified reference material. To do that, they need to demonstrate the components of uncertainty in their analytical work. At NIST, the goal is to demonstrate traceability to SI units to ensure that results are accepted on a worldwide basis. For XRF spectrometry with borate fusion, traceability to SI is achieved through calibration with spectrometric solution standards or high‐purity compounds. The method is capable of achieving relative expanded uncertainty estimates (95% confidence level) of 1% or lower. In this paper, the capability is demonstrated for low alloy‐steel and an AlTiNbW aerospace alloy. XRF results are compared with certified values and with results from atomic emission methods through a simple bias test. NIST uses the borate fusion/XRF method as part of the value assignment process for Standard Reference Materials®. Copyright © 2004 John Wiley & Sons, Ltd.
The effect of aspirin on the ventilatory response to exercise in chronic heart failure
Authors: Witte Klaus K.A. , Clark Andrew L. 
Published: November 2004

AbstractIntroduction:Patients with chronic heart failure (CHF) experience breathlessness and fatigue on exercise. One of the abnormalities seen on maximal exercise testing is an increased ventilatory response to exercise (Ve/Vco2 slope). The cause of this is unknown, but is likely to be due to a combination of interacting peripheral and central factors. Recent data have demonstrated a relation between Ve/Vco2 slope and prostaglandin levels in contracting muscles. The present study examined the influence of the presence of a potent non‐selective prostaglandin inhibitor, aspirin, on the ventilatory response to exercise in a group of patients with CHF.Methods:We investigated the ventilatory response to exercise of 120 consecutive patients in sinus rhythm attending a specialist heart failure clinic. We excluded those taking clopidogrel (six patients) and those on both warfarin and aspirin or taking other non‐steroidal anti‐inflammatory agents (five patients). The other 109 patients were grouped according to whether they were taking aspirin (n=52 (48%)) or not (n=57 (52%)). Each patient underwent echocardiography to assess left ventricular function, and exercise testing with metabolic gas exchange to derive peak oxygen consumption (pVo2) and the Ve/Vco2 slope.Results:The groups were similar in terms of age, (67 (13) vs. 66 (12) years; P=0.34) drug use, heart failure aetiology, left ventricular function (ejection fraction; 33.3 (9.4) vs. 31.8 (9.9)%; P=0.05)) and exercise tolerance (pVo2; 20.4 (5.3) vs. 19.9 (6.0); P=0.68, and Ve/Vco2 slope; 35.4 (6.2) vs. 35.7 (9.3); P=0.73). There was no difference in the ventilatory response to exercise or the symptoms of breathlessness between the two groups.Conclusions:Aspirin does not appear to affect exercise performance in CHF.