bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics of penicillin G hydrolysis in an electro‐membrane reactor
Authors: Pr̆ibyl Michal , Chmelíková Růz̆ena , Hasal Pavel , Marek Milos̆ 
Published: September 2002

AbstractAnalysis of penicillin G hydrolysis in a membrane reactor with membrane‐entrapped penicillin G acylase is performed using a mathematical model of the reactor system. An electric field imposed to the reactor is considered to enhance transport rates of reaction components and reaction rate. Diffusion, electrophoretic migration and electro‐osmotic flux across the membrane are considered. The analysis focuses on possible effects of the principal operational parameters (electric field intensity, inlet substrate concentration, membrane thickness) on reactor performance. Multiplicities of steady states are frequently encountered. The membrane reactor performance can be easily targeted towards the required reaction regime by applying a constant or periodically varying electric field to the system. The periodic alternation of the polarity of the electric field substantially increases the effectiveness factor of penicillin hydrolysis compared with the steady state operation. Proper adjustments of electric field intensity may also compensate for the decay in enzyme activity.© 2001 Society of Chemical Industry
Seasonal changes in the preferred body temperature, cardiovascular, and respiratory responses to hypoxia in the toad, Bufo paracnemis
Authors: Bícego‐Nahas Kênia Cardoso , Gargaglioni Luciane Helena , Branco Luiz Guilherme Siqueira 
Published: September 2002

AbstractEstivation is accompanied by a reduction of oxygen consumption in amphibians during drought. We tested the hypothesis that, during the dry season, the toad Bufo paracnemis selects a lower preferred body temperature &lpar;Tb&rpar;, and would be less sensitive to hypoxia, than during its active period. Therefore, during winter &lpar;dry season in S&atilde;o Paulo state, Brazil&rpar; and summer, we measured the effects of hypoxia &lpar;7&percnt; inspired O2&rpar; on preferred Tb. Additionally, pulmonary ventilation, heart rate, blood pressure, and oxygen consumption were also measured in toads at 15 and 25&deg;C. Blood gases were measured at 25&deg;C. Oxygen consumption was significantly higher during summer in toads at 25&deg;C. Under normoxia, preferred Tb was higher during summer than during winter, and hypoxia caused a drop in preferred Tb during both seasons. In both seasons, toads at 15&deg;C showed reduced pulmonary ventilation, heart rate, and blood pressure, and hypoxia had no effect. At 25&deg;C during summer only, hypoxia caused an increase in ventilation. Season had no effect on blood gases. We conclude that B. paracnemis displays an endogenous seasonal pattern of thermoregulation and control of ventilation. The decreased preferred Tb and the physiological responses to hypoxia may be beneficial to toads encountering drought and when food is not available. J. Exp. Zool. 289:359&ndash;365, 2001. &copy; 2001 Wiley&hyphen;Liss, Inc.
Almost all graphs with high girth and suitable density have high chromatic number
Authors: Osthus Deryk , Prömel Hans Jürgen , Taraz Anusch 
Published: September 2002

AbstractErdös proved that there exist graphs of arbitrarily high girth and arbitrarily high chromatic number. We give a different proof (but also using the probabilistic method) that also yields the following result on the typical asymptotic structure of graphs of high girth: for all ℓ ≥ 3 and k ∈ ℕ there exist constants C1 and C2 so that almost all graphs on n vertices and m edges whose girth is greater than ℓ have chromatic number at least k, provided that $C_{1}n\,\leq\, m\,\leq\, C_{2}n^{\ell /(\ell -1)}$. © 2001 John Wiley & Sons, Inc. J Graph Theory 37: 220–226, 2001
Intellectual disability and the myth of the changeling myth
Authors: Goodey C. F. , Stainton Tim 
Published: September 2002

AbstractThis article investigates the historical sources for the idea of the “changeling” or substitute child as an explanation for congenital intellectual disability. Pre‐modern sources for this idea are elite and theological as much as popular and folkloric, nor do they refer to intellectual disability in any sense recognizable to us. Rather, both the concept of intellectual disability and the notion of a transhistorical changeling myth emerge from the historical core of modern psychology. © 2001 John Wiley & Sons, Inc.
Assessors and use of assessment centre dimensions: a fresh look at a troubling issue*
Authors: Lievens Filip 
Published: September 2002

AbstractPrevious studies on the construct validity of assessment centres have generally produced puzzling results. The premise of this study is that these prior studies were relatively one‐sided. Actually, most previous studies were field studies, which typically used the multitrait–multimethod approach to distinguish between two sources of variance (i.e., exercises and dimensions). Therefore, this study aims to shed light on the issue of assessment centre construct validity by addressing substantive and methodological concerns inherent in previous research. In this study, 85 industrial and organizational psychology students and 39 managers rated videotaped assessment centre candidates in three exercises on six dimensions. Results from generalizability analyses showed that assessors' ratings were relatively veridical. In addition, when assessors rated candidates whose performances varied across dimensions and whose performances were relatively consistent across exercises, they were reasonably able to differentiate among the various dimensions. They also rated such candidate profiles similarly on the various dimensions across exercises. When assessors rated a candidate profile without clear performance fluctuations across dimensions, distinctions about dimensions were more blurred. Results from student and managerial assessors were similar, although managers distinguished somewhat less between the various dimensions. The research and practical implications of these findings are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Precipitation and atmospheric circulation patterns at mid‐latitudes of Asia
Authors: Aizen Elena M. , Aizen Vladimir B. , Melack John M. , Nakamura Tsutomu , Ohta Takeshi 
Published: September 2002

AbstractAnalyses of the coupling between large‐scale atmospheric patterns and modifications of regional precipitation regimes at seasonal and annual time scales in different terrain of mid‐latitudes in Asia, including western Siberia, Tien Shan and Pamir mountains, and plains of middle Asia and Japanese Islands, were examined based on data from 57 and 88 hydro‐climatic stations with 100 and 60 year records, respectively. For the past 100 years, a positive trend in precipitation was revealed in western Siberia, northern regions of Tien Shan and Japanese Islands. North Atlantic Oscillation (NAO) and West Pacific Oscillation (WPO) indices have inverse associations, with average amount of precipitation in western Siberia and in mountains and plains of middle Asia, and positive correlation in central and western regions of Japanese Islands. The Pacific North American (PNA) index is positively correlated with annual precipitation over most of the Japanese Islands. Northern Asian (NA) positive anomalies lead to decrease in winter precipitation in the western and eastern regions of Japanese Islands. We did not find significant impact of PNA or NA on precipitation in middle Asia. We suggest that during the last century, impacts of the western jet stream increased in the northern regions of Tien Shan and Japanese Islands, and weakened in the eastern Japanese Islands. There is a suggestion that conditions are more favourable for precipitation development over continental regions of Asia when the Siberian High is positioned further to the east than further to the west. During dominant development of a zonal atmospheric pattern, the annual and seasonal precipitation decreased over most regions in continental Asia and central Japan. Copyright © 2001 Royal Meteorological Society
Using the standardized precipitation index for flood risk monitoring
Authors: Seiler R. A. , Hayes M. , Bressan L. 
Published: September 2002

AbstractFlood risk and the critical time of occurrence are difficult to monitor and detect. The availability and application of adapted indices may allow not only continuous monitoring of hydrological conditions in flood‐prone areas, but also the potential threat of possible flood events in order to promote preventive actions to mitigate the impacts of the phenomenon. The standardized precipitation index (SPI) was developed for drought detection and monitoring. However, because of its characteristics, the SPI can also be used as a tool to monitor wetter‐than‐normal conditions. The aim of this paper, based on the recurrent floods affecting the southern Cordoba Province in Argentina, is to analyse the potential of the SPI as a tool for monitoring flood risk in that region. Results indicate that the SPI satisfactorily explains the development of conditions leading up to the three main flood events to occur in the region during the past 25 years. This fact supports the proposal for applying the SPI as an effective component of a regional system for climate risk monitoring. Copyright © 2002 Royal Meteorological Society.
Marine conditions in central Sweden during the early Preboreal as inferred from a stable oxygen isotope gradient
Authors: Schoning Kristian , Klingberg Fredrik , Wastegård Stefan 
Published: September 2002

AbstractThe marine benthic fauna and the δ18Ocof foraminifers and ostracods from six sites situated on a west–east transect through central Sweden have been analysed in order to estimate the palaeosalinity and palaeocirculation in this shallow‐marine environment. The measurements have been undertaken on material from the early Preboreal, when the Baltic Basin was in contact with the North Sea through straits in central Sweden. The δ18Ocvalues have a more negative value towards the east, indicating decreasing salinity. This was the result of limited possibilities for marine water to penetrate into the Baltic Basin and the mixing with freshwater from the melting Fennoscandian ice‐sheet. Four water masses existed in the area: a surface layer of freshwater, marine water from the North Sea, brackish–marine intermediate water on the Swedish west coast and brackish Yoldia Sea water in the Baltic Basin. The chronology is based on radiocarbon dates of marine fossils and, at one site, on the occurrence of the Vedde Ash (10 400–10 30014C yr BP). This is the first record from marine settings in Sweden. Copyright © 2001 John Wiley & Sons, Ltd.
Effects of legume processing on calcium, iron and zinc contents and dialysabilities
Authors: Sebastiá Vicente , Barberá Reyes , Farré Rosaura , Lagarda María Jesús 
Published: September 2002

AbstractLegumes are a good source of calcium, iron and zinc, but are also a source of phytates and dietary fibre components that can negatively affect the bioavailability of these minerals. To estimate the latter, an in vitro dialysis method can be applied that gives the dialysability of a mineral as an estimate of its availability for absorption. Calcium, iron and zinc contents and dialysabilities in three legumes (beans, chickpeas and lentils) and the effects of cooking treatments and industrial processing on these parameters were studied. Beans had the highest calcium content (1.54 g kg−1 dry matter (DM)) and chickpeas the lowest iron content (46.9 mg kg−1 DM), whilst the zinc contents were similar in all three raw legumes (33.7–36.9 mg kg−1 DM). Traditional and microwave cooking reduced the mineral contents by 9.7–36.4% for calcium, 14.2–31% for iron and 11.1–28.9% for zinc. The dialysabilities of calcium with respect to the values for the raw products were also reduced by these cooking techniques. Industrially processed legumes had higher dialysabilities of calcium, iron and zinc than traditionally or microwave cooked legumes.© 2001 Society of Chemical Industry
Kinetics and products of the reactions of selected diols with the OH radical
Authors: Bethel Heidi L. , Atkinson Roger , Arey Janet 
Published: September 2002

AbstractUsing a relative rate method, rate constants have been measured at 296 ± 2 K for the gas‐phase reactions of OH radicals with 1,2‐butanediol, 2,3‐butanediol, 1,3‐butanediol, and 2‐methyl‐2,4‐pentanediol, with rate constants (in units of 10−12 cm3 molecule−1 s−1) of 27.0 ± 5.6, 23.6 ± 6.3, 33.2 ± 6.8, and 27.7 ± 6.1, respectively, where the error limits include the estimated overall uncertainty of ±20% in the rate constant for the reference compound. Gas chromatographic analyses showed the formation of 1‐hydroxy‐2‐butanone from 1,2‐butanediol, 3‐hydroxy‐2‐butanone from 2,3‐butanediol, 1‐hydroxy‐3‐butanone from 1,3‐butanediol, and 4‐hydroxy‐4‐methyl‐2‐pentanone from 2‐methyl‐2,4‐pentanediol, with formation yields of 0.66 ± 0.11, 0.89 ± 0.09, 0.50 ± 0.09, and 0.47 ± 0.09, respectively, where the indicated errors are the estimated overall uncertainties. Pathways for the formation of these products are presented, together with a comparison of the measured and estimated rate constants and product yields. © 2001 John Wiley & Sons, Inc. Int J Chem Kinet 33: 310–316, 2001
Raised and sunken bed technique for agroforestry on alkali soils of northwest India
Authors: Dagar J. C. , Sharma H. B. , Shukla Y. K. 
Published: September 2002

AbstractMany forest tree and fruit species can be raised on highly alkali soil (pH > 10) but some of them such as pomegranate (Punica granatum) are unable to tolerate water stagnation. To avoid water stagnation problems during the monsoon the raised and sunken bed technique has been found suitable for agroforestry practices on highly alkali soil. One fruit‐yielding pomegranate and one oil‐yielding salvadora (Salvadora persica) plantation species were successfully grown on raised bunds to avoid water stagnation and rice–wheat and berseem–kallar grass rotation were grown on sunken‐beds constructed for the purpose. The experiment was initiated in 1996 and the above two crop rotations were followed for two consecutive years starting in the summer season. Results of these experiments have also shown that good growth of plantations, on an average 4·3 to 4·9 t ha−1 rice (salt tolerant var. CSR‐10) and 1·2 to 1·4 t ha−1 wheat (KRL 1–4), were obtained in sunken beds. In another rotation 21·3 to 36.8 t ha−1 fresh forage of kallar grass (Leptochloa fusca) and 44·9 to 47·8 t ha−1 fresh forage of berseem (Trifolium alexandrium) were obtained. After two years of the experiment, soil amelioration in terms of reduction in soil pH was significant. The effect of plantation in reducing soil pH showed that the pomegranate and salvadora both helped in reduction of soil pH, but the latter due to its well‐developed lateral root system was more efficient in lowering the soil pH even at lower depths. The reduction in soil pH by the berseem–kallar grass rotation was better than under rice–wheat rotation. Copyright © 2001 John Wiley & Sons, Ltd.
Mystery shopping: Using deception to measure service performance
Authors: Wilson Alan M. 
Published: September 2002

AbstractThis article reports on a program of exploratory research aimed at examining the practice of mystery shopping in service organizations. Mystery shopping, a form of participant observation, uses researchers to deceive customer service personnel into believing that they are serving real customers or potential customers. The research focused on the views of senior managers responsible for commissioning mystery shopping research and directors of market research agencies responsible for the provision of such research. The research findings identify the manner in which mystery shopping is used and the methods used to maximize the reliability of the technique. The study also revealed that employees' acceptance of this form of deception appears to be critical if the results are to be taken seriously by service personnel and if industrial relations within the organization are not to suffer. © 2001 John Wiley & Sons, Inc.
A stable calcium gradient near the plasma membrane
Authors: Braiman Alex , Gold'shtein Vladimir , Priel Zvi 
Published: September 2002

AbstractThe influx of calcium ions from extracellular space plays a central role in regulation of function of living cells. It has been hypothesized that calcium influx causes a rise in intracellular calcium concentration ([Ca2+]i) near the plasma membrane, thereby facilitating regulation of membrane associated processes without flooding the cell with Ca2+. Such a localization is extremely important, since high [Ca2+]i is toxic to cells. However, existence of sustained areas of different Ca2+ concentrations within a continuous aquatic medium is not a trivial phenomenon. The mathematical model presented here evaluates the cytosolic concentration of Ca2+ as a function of time and distance from the plasma membrane. The model has verified quantitatively the feasibility of a stable Ca2+ gradient in the cytosol with high values of Ca2+ concentration near the plasma membrane and evaluated its properties as a function of different cellular parameters. The formation of the gradient does not require special distribution of the intracellular contents, channels and pumps. However, it requires buffering of the cytosolic calcium by the intracellular stores and that the rate of calcium release from the stores near the plasma membrane be higher than in other parts of the cell. We suggest that this model can provide an adequate description of the elevated calcium plateau generally observed in electrically non‐excitable cells. Copyright © 2001 John Wiley & Sons, Ltd.
17O NMR studies on (E)‐3‐arylidenechromanone and ‐flavanone derivatives
Authors: Tóth Gábor , Simon András , Lévai Albert , Kählig Hanspeter , Kalchhauser Hermann 
Published: September 2002

Abstract17O NMR data for some 3‐arylidenechromanones and ‐flavanones are discussed in terms of mesomeric and steric substituent interactions. The transmission of long‐range substituent effects was studied. 17O NMR chemical shifts were correlated with Hammett σp+ values for 4′‐substituted derivatives. Copyright © 2001 John Wiley & Sons, Ltd.
Structure and folding of glucagon‐like peptide‐1‐(7–36)‐amide in aqueous trifluoroethanol studied by NMR spectroscopy
Authors: Chang Xiaoqing , Keller Danielle , Bjørn Søren , Led Jens J. 
Published: September 2002

AbstractThe conformational changes of free, monomeric glucagon‐like peptide‐1‐(7–36)‐amide (GLP‐1) in aqueous solution with increasing concentrations of 2,2,2‐trifluoroethanol (TFE) were monitored by NMR spectroscopy. It was found that GLP‐1 gradually assumes a stable, single‐stranded helical structure in water solution when the TFE concentration is increased from 0 to 35% (v/v). No further structural changes were observed at higher TFE concentrations. The structure of GLP‐1 in 35% TFE was determined from 292 distance restraints and 44 angle restraints by distance geometry, simulating annealing and restrained energy minimization. The helical structure extends from T7 to K28, with a less well‐defined region around G16 and a disordered six‐residue N‐terminal domain. The folding process of GLP‐1 from random coil (in water) to helix (in 35% TFE) is initiated by the formation of the C‐terminal segment of the helix that is extended gradually towards the N‐terminus of the peptide with increasing concentration of TFE. The exchange rates of the slow exchanging amide protons indicate that the C‐terminal part of the helix is more stable than the N‐terminal part. Copyright © 2001 John Wiley & Sons, Ltd.
Ovarian expression of human insulin‐like growth factor‐I in transgenic mice results in cyst formation
Authors: Dyck Michael K. , Parlow A.F. , Sénéchal Jean‐François , Sirard Marc‐André , Pothier François 
Published: September 2002

AbstractInsulin‐like growth factor‐I (IGF‐I) has been implicated in a wide variety of physiological processes including ovarian function. To better understand the ovarian role of IGF‐I, transgenic mice harbouring a human IGF‐I cDNA (hIGF‐I) under the control of the mouse LH receptor promoter were generated. Expression of the hIGF‐I, determined by Northern blot, was found to occur in the gonad tissues of these transgenic mice. The hIGF‐I protein was also detectable by radioimmunoassay in ovarian extracts as well as in the plasma. The fertility of mating transgenic females, as estimated by the number of implantation sites post‐coitum, did not appear to be affected. However, transgenic females who failed to mate and produce offspring were found to possess polycystic ovaries. Evaluation of testosterone, estradiol, and LH levels revealed that transgenic animals had significantly elevated circulating levels of testosterone compared to their non‐transgenic littermates, while LH levels in transgenic females were significantly lower. Yet, estradiol appeared to be unaffected. These results support the contention that the IGF system plays an important role in ovarian function and that an imbalance in this system may result in ovarian pathology. Mol. Reprod. Dev. 59:178–185, 2001. © 2001 Wiley‐Liss, Inc.
Simultaneous noninvasive measurement of CBF and CBV using double‐echo FAIR (DEFAIR)
Authors: Thomas David L. , Lythgoe Mark F. , Calamante Fernando , Gadian David G. , Ordidge Roger J. 
Published: September 2002

AbstractA new method for measuring cerebral blood flow (CBF) and cerebral blood volume (CBV) noninvasively using MRI is presented. The approach is based on the technique of arterial spin labelling (ASL), in which CBF‐based contrast is generated by controlled modulation of the longitudinal magnetization of the blood. The proposed method also uses differences in T2 between tissue and blood to differentiate the two compartments and allow assessment of the relative size of each. Two successive EPI images are acquired following spin preparation using either a slice‐selective or global inversion pulse, and the technique is therefore referred to as double‐echo FAIR (DEFAIR). DEFAIR is demonstrated in the normal gerbil brain and during hypothermia, where reductions of both CBF and CBV are known to occur. It is also shown theoretically that this method can be extended to include a measurement of oxygen extraction fraction. The main drawbacks of the technique are the long acquisition time and relatively low sensitivity to hemodynamic changes compared to conventional qualitative T‐weighted BOLD contrast, which may limit its applicability and practical use in monitoring functional cerebral activation. However, the technique can be used repetitively in longer‐term time course studies due to its noninvasive and quantitative nature. Magn Reson Med 45:853–863, 2001. © 2001 Wiley‐Liss, Inc.
Cramér–Rao bounds: an evaluation tool for quantitation
Authors: Cavassila S. , Deval S. , Huegen C. , van Ormondt D. , Graveron‐Demilly D. 
Published: September 2002

AbstractThe Cramér–Rao lower bounds (CRBs) are the lowest possible standard deviations of all unbiased model parameter estimates obtained from the data. Consequently they give insight into the potential performance of quantitation estimators. Using analytical CRB expressions for spectral parameters of singlets and doublets in noise, one is able to judge the precision as a function of spectral and experimental parameters. We point out the usefulness of these expressions for experimental design. The influence of constraints (chemical prior knowledge) on spectral parameters of the peaks of doublets is demonstrated and the inherent benefits for quantitation are shown. Copyright­© 2001 John Wiley & Sons, Ltd.
Abbreviations used:

CRB

Cramér‐Rao lower bounds