bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antimaterie in der Milchstraße
Authors: Bührke Thomas 
Published: February 2008

AbstractVor etwa 30 Jahren entdeckten Astronomen Gammastrahlung, die aus der Richtung des Zentrums unserer Milchstraße kommt. Sie besitzt eine Energie von 511 keV und stammt somit offenbar von der Vernichtung von Elektronen und deren Antiteilchen, Positronen. Da Antimaterie in der Natur normalerweise nicht vorkommt, wurden zahlreiche Erklärungen für dieses Phänomen vorgeschlagen. Auch exotische Theorien, wonach die Strahlung beim Zerfall von hypothetischen Dunkle‐Materie‐Teilchen frei wird, wurden diskutiert. Jetzt hat ein internationales Team um Georg Weidenspointner vom Max‐Planck‐Institut für extraterrestrisch Physik in Garching herausgefunden, dass die Positronen wahrscheinlich in ungewöhnlichen Doppelstern‐Systemen entstehen.
Synthesis of polypeptides from activated urethane derivatives of α‐amino acids
Authors: Kamei Yasutaka , Sudo Atsushi , Nishida Haruo , Kikukawa Kiyoshi , Endo Takeshi 
Published: February 2008

AbstractA series of activated urethane‐type derivatives of α‐amino acids were synthesized and applied to polypeptide synthesis. The urethane used herein, N‐(4‐nitrophenoxycarbonyl)‐α‐amino acids 1, were synthesized by N‐carbamoylation of γ‐benzyl‐L‐glutamate, β‐benzyl‐L‐aspartate, L‐leucine, L‐phenylalanine, and L‐proline, with 4‐nitrophenyl chloroformate. When 1 was dissolved in N,N‐dimethylacetamide (DMAc) and heated at 60 °C, it was smoothly converted into the corresponding polypeptides with releasing 4‐nitrophenol and carbon dioxide. Spectroscopic analyses of the obtained polypeptides revealed that they were comparable with the authentic polypeptides synthesized by the ring‐opening polymerizations of amino acid N‐carboxyanhydrides (NCAs). Besides the successful polycondensations of a series of 1, their polycondensations of 1a and other 1 were also successfully carried out to obtain the corresponding statistic copolypeptides. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2525–2535, 2008
The conserved salt bridge linking two C‐terminal β/α units in homodimeric triosephosphate isomerase determines the folding rate of the monomer
Authors: Reyes‐López César A. , González‐Mondragón Edith , Benítez‐Cardoza Claudia G. , Chánez‐Cárdenas María E. , Cabrera Nallely , Pérez‐Montfort Ruy , Hernández‐Arana Andrés 
Published: February 2008

AbstractTriosephosphate isomerase (TIM), whose structure is archetypal of dimeric (β/α)8 barrels, has a conserved salt bridge (Arg189–Asp225 in yeast TIM) that connects the two C‐terminal β/α segments to rest of the monomer. We constructed the mutant D225Q, and studied its catalysis and stability in comparison with those of the wild‐type enzyme. Replacement of Asp225 by Gln caused minor drops in kcat and KM, but the catalytic efficiency (kcat/KM) was practically unaffected. Temperature‐induced unfolding–refolding of both TIM samples displayed hysteresis cycles, indicative of processes far from equilibrium. Kinetic studies showed that the rate constant for unfolding was about three‐fold larger in the mutant than in wild‐type TIM. However, more drastic changes were found in the kinetics of refolding: upon mutation, the rate‐limiting step changed from a second‐order (at submicromolar concentrations) to a first‐order reaction. These results thus indicate that renaturation of yTIM occurs through a uni–bimolecular mechanism in which refolding of the monomer most likely begins at the C‐terminal half of its polypeptide chain. From the temperature dependence of the refolding rate, we determined the change in heat capacity for the formation of the transition state from unfolded monomers. The value for the D225Q mutant, which is about 40% of the corresponding value for yTIM, would implicate the folding of only three quarters of a monomer chain in the transition state. Proteins 2008. © 2008 Wiley‐Liss, Inc.
Enhanced self‐ordering of anodic ZrO2 nanotubes in inorganic and organic electrolytes using two‐step anodization
Authors: Berger Steffen , Faltenbacher Josef , Bauer Sebastian , Schmuki Patrik 
Published: February 2008

AbstractThis work reports on the optimized growth of self‐ordered ZrO2 nanotubes in inorganic water‐based and organic electrolyte systems containing small amounts of fluoride employing a two‐step anodization process. We show how surface pretreatments of the metallic Zr substrate can drastically improve the growth and morphology of the resulting anodic ZrO2 nanotube arrays. Using two step anodization and employing organic electrolytes, highly regular and ordered nanotubular ZrO2 oxide layers can be grown to significantly increased tube lengths compared with aqueous electrolytes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Instream flow determination using a multiple input fuzzy‐based rule system: a case study
Authors: Ahmadi‐Nedushan B. , St‐Hilaire A. , Bérubé M. , Ouarda T. B. M. J. , Robichaud É. 
Published: February 2008

AbstractThe attempts made to manage water to meet human requirements should also consider the needs of freshwater species and ecosystems. There are many tools available to assess instream flow needs, one of which is the use of habitat preference models. In this study, a fuzzy approach was used for modelling habitat preferences for two life stages of Atlantic salmon (Salmo salar). Experienced fish biologists and technicians contributed to the development of fuzzy sets and fuzzy preference rules for spawning and parr habitat. Fuzzy sets were defined for water depth, velocity and substrate composition. Fuzzy preference rules for the two life stages were then defined as sets of IF–THEN rules relating the physical attributes to habitat suitability. The fuzzy suitability indices are then used to obtain weighted usable area (WUA) at different discharges and to estimate the ecologic flow required to preserve habitat. Different methods are applied to combine the membership function and rules defined by the experts. A sensitivity analysis of rules of the combined system indicated that a limited number of rules are determinant and results are highly dependent on the consequences of these rules. A modification in the consequence of these rules can significantly alter WUA estimations. It is therefore recommended to combine the knowledge of many experts in the elicitation process and to quantify the uncertainty associated with the combination of expert knowledge. Copyright © 2007 John Wiley & Sons, Ltd.
Sustainable reservoir operation: can we generate hydropower and preserve ecosystem values?
Authors: Jager Henriette I. , Smith Brennan T. 
Published: February 2008

AbstractHydroelectric power provides a cheap source of electricity with few carbon emissions. Yet, reservoirs are not operated sustainably, which we define as meeting societal needs for water and power while protecting long‐term health of the river ecosystem. Reservoirs that generate hydropower are typically operated with the goal of maximizing energy revenue, while meeting other legal water requirements. Reservoir optimization schemes used in practice do not seek flow regimes that maximize aquatic ecosystem health. Here, we review optimization studies that considered environmental goals in one of three approaches. The first approach seeks flow regimes that maximize hydropower generation, while satisfying legal requirements, including environmental (or minimum) flows. Solutions from this approach are often used in practice to operate hydropower projects. In the second approach, flow releases from a dam are timed to meet water quality constraints on dissolved oxygen (DO), temperature and nutrients. In the third approach, flow releases are timed to improve the health of fish populations. We conclude by suggesting three steps for bringing multi‐objective reservoir operation closer to the goal of ecological sustainability: (1) conduct research to identify which features of flow variation are essential for river health and to quantify these relationships, (2) develop valuation methods to assess the total value of river health and (3) develop optimal control softwares that combine water balance modelling with models that predict ecosystem responses to flow. Copyright © 2007 John Wiley & Sons, Ltd.
The cover time of the giant component of a random graph
Authors: Cooper Colin , Frieze Alan 
Published: February 2008

AbstractWe study the cover time of a random walk on the largest component of the random graph Gn,p. We determine its value up to a factor 1 + o(1) whenever np = c > 1, c = O(lnn). In particular, we show that the cover time is not monotone for c = Θ(lnn). We also determine the cover time of the k‐cores, k ≥ 2. © 2008 Wiley Periodicals, Inc. Random Struct. Alg., 2008
Mobile GPS carrier phase tracking using a novel intelligent dual‐loop receiver
Authors: Mao Wei‐Lung , Chen An‐Bang 
Published: February 2008

AbstractCarrier phase information is necessary for accurate measurements in global positioning system (GPS) applications. This paper presents a novel intelligent GPS carrier tracking loop with variable‐bandwidth characteristics for fast acquisition and better tracking capability in the presence of dynamic environments. Our dual‐loop receiver is composed of a frequency‐locked loop‐assisted phase‐locked loop structure, the fuzzy controllers (FCs), and the ATAN discriminator functions. The soft‐computing FCs provide the time‐varying loop gains to perform accurate and reliable control of the dual‐loop paradigm. Once the phase dynamic errors become large under kinematic conditions, the fuzzy loop gains increase adaptively and achieve rapid acquisition. On the other hand, when the tracking errors approach zero in the steady state, the loop gains decrease and the corresponding dual‐loop receiver returns to a narrowband system. Four types of carrier phase signals, i.e. phase offset, decaying sinusoidal phase jitter, frequency offset, and frequency ramp offset, are considered to emulate realistic mobile circumstances. Simulation results show that our proposed receiver does achieve a superior performance over conventional tracking loops in terms of faster settling time and wider acquisition range while preventing the occurrence of cycle slips. Copyright © 2008 John Wiley & Sons, Ltd.
What can Raman spectroscopy and spectroscopic ellipsometry bring for the characterisation of thin films and materials surface?
Authors: Lewandowska Renata , Gaillet Mélanie , Le Bourdon Gwénaëlle , Eypert Céline , Morel Sophie , Naudin Coralie , Stchakovsky Michel 
Published: February 2008

AbstractEllipsometry and Raman spectroscopy offer a wide range of applications for the characterisation of thin films, material surfaces and interfaces. Both analytical methods are non‐contact, non‐destructive and do not require any sample preparation. Firstly, theoretical basics of both techniques will be presented, and then some examples will be described. Copyright © 2008 John Wiley & Sons, Ltd.
Estimation of fetal weight by measurement of fetal thigh soft‐tissue thickness in the late third trimester
Authors: Scioscia M. , Scioscia F. , Vimercati A. , Caradonna F. , Nardelli C. , Pinto L. R. , Selvaggi L. E. 
Published: February 2008

AbstractObjectiveThe accuracy of current formulae for the sonographic estimation of fetal weight (EFW) is compromised by significant intra‐ and interobserver variability of biometrical measurements, particularly circumferences. The aim of this study was to assess the reliability of the linear measurement of mid‐thigh soft‐tissue thickness (STT) and to derive a novel formula for EFW.MethodsThis was a prospective study involving 388 singleton uncomplicated pregnancies. There were three consecutive phases: (1) to verify the relationship between STT and birth weight, (2) to derive a novel formula for EFW using femur length and STT only, and (3) to test the accuracy of the new equation. Only the 290 patients who delivered within 48 h of measurement were considered for the analysis. A comparison with other formulae was performed.ResultsSTT was significantly correlated with both abdominal circumference and birth weight (r2 = 0.36 and 0.46, respectively; P < 0.001). Both intra‐ and interobserver variability were satisfactory (0.44 ± 0.27 and 0.57 ± 0.35 mm, respectively). The equation for EFW was developed using multiple stepwise regression analysis (EFW = − 1687.47 + (54.1 × femur length) + (76.68 × STT)) and tested prospectively on 69 patients. The new formula yielded results (r = 0.79) that were slightly better in accuracy than two other published equations, and had an absolute mean error of < 15% in 97% of cases.ConclusionsOur findings confirm the potential of the linear measurement of mid‐thigh STT as a valuable parameter for the sonographic assessment of fetal growth and EFW. Our new equation is apparently at least as reliable as the most widely used formulae for EFW. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Ductus venosus Doppler in fetuses with cardiac defects and increased nuchal translucency thickness
Authors: Maiz N. , Plasencia W. , Dagklis T. , Faros E. , Nicolaides K. 
Published: February 2008

AbstractObjectiveTo examine the possible role of Doppler ultrasound assessment of ductus venosus blood flow in screening for major cardiac defects in chromosomally normal fetuses with increased nuchal translucency (NT) thickness at 11 + 0 to 13 + 6 weeks' gestation.MethodsDuctus venosus blood flow velocity waveforms were obtained immediately before chorionic villus sampling for fetal karyotyping in fetuses with NT thickness of 3.5 mm or more at 11 + 0 to 13 + 6 weeks of gestation. In the chromosomally normal group fetal echocardiography was performed by a specialist pediatric cardiologist at 11 + 0 to 13 + 6 weeks and/or 18–22 weeks' gestation.ResultsMajor cardiac defects were diagnosed in 16 (8.4%) of the 191 chromosomally normal fetuses. Reversed or absent flow in the ductus venosus during atrial contraction was observed in 11 of the 16 (68.8%) fetuses with cardiac defects and in 40 of the 175 (22.9%) with no cardiac defects. Multivariate analysis demonstrated that the prevalence of an abnormal A‐wave in the ductus venosus in fetuses without major cardiac defects increased with fetal NT thickness (odds ratio (OR), 1.463; 95% CI, 1.183–1.809; P < 0.0001) but in those with cardiac defects it did not change significantly with NT thickness (OR, 2.054; 95% CI, 0.573–7.360; P = 0.269). The likelihood ratio for a major cardiac defect when the ductus venosus flow was abnormal decreased with fetal NT thickness from 4.58 at NT 3.5 mm to 2.47 for NT 5.5 mm, and the likelihood ratio when the ductus venosus flow was normal increased from 0.37 at NT 3.5 mm to 0.43 for NT 5.5 mm.ConclusionIn chromosomally normal fetuses with increased NT the finding of an absent or reversed A‐wave in the ductus venosus is associated with a three‐fold increase in the likelihood of a major cardiac defect, whereas the finding of normal ductal flow is associated with a halving in risk for such defects. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Outcome of antenatally diagnosed cardiac rhabdomyoma: case series and a meta‐analysis
Authors: Chao A. S. , Chao A. , Wang T. H. , Chang Y. C. , Chang Y. L. , Hsieh C. C. , Lien R. , Su W. J. 
Published: February 2008

AbstractObjectivesRhabdomyoma, the most common primary fetal cardiac tumor, is often associated with tuberous sclerosis (TS). We aimed to evaluate outcome in cases diagnosed with fetal cardiac rhabdomyoma.MethodsThis study presents 11 cases with fetal cardiac rhabdomyoma. In addition, all relevant published cases of antenatally diagnosed cardiac rhabdomyoma since 1982 were identified from MEDLINE. We evaluated the following risk factors associated with clinical impact and perinatal outcome: family history of TS, gestational age at diagnosis, tumor size, site and number of tumors, tumor progression, and associated intracardiac and extracardiac anomalies.ResultsIn this meta‐analysis, 138 cases, including nine newly added by us, were categorized into Group A (107 live babies) and Group B (16 neonatal deaths and 15 intrauterine fetal deaths). Univariate analysis showed that large cardiac tumors (P < 0.0001), fetal dysrhythmia (P < 0.0001) and hydrops (P < 0.0001) were strong predictors of neonatal outcome. Tumor size ≥ 20 mm (relative risk (RR), 20.6; 95% CI, 2.2–195.9; P = 0.009) and fetal dysrhythmia (RR, 13.6; 95% CI, 2.9–62.3; P = 0.001) were significantly associated with neonatal morbidity. TS, present in 85/133 (63.9%) cases, was significantly associated with multiple cardiac tumors (P < 0.0001) and family history of TS (P = 0.02).ConclusionsLarge tumor size and hydrops are significantly associated with poor neonatal outcome, whereas family history of TS and multiple fetal cardiac tumors are associated with TS. Any sonographic detection of a fetal cardiac tumor should warrant further investigation for the possible presence of associated disorders. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Comparison of the learning curves of digital examination and transabdominal sonography for the determination of fetal head position during labor
Authors: Rozenberg P. , Porcher R. , Salomon L. J. , Boirot F. , Morin C. , Ville Y. 
Published: February 2008

AbstractObjectivesTo evaluate the learning curve of transabdominal sonography for the determination of fetal head position in labor and to compare it with that of digital vaginal examination.MethodsA student midwife who had never performed digital vaginal examination or ultrasound examination was recruited for this study. Instructions on how to perform digital vaginal examination and ultrasound examination were given before and after completing the first vaginal and ultrasound examinations, and repeated for each subsequent examination for as long as necessary. Digital and ultrasound diagnoses of the fetal head position were always performed first by the student midwife, and repeated by an experienced midwife or physician. The learning curve for identification of the fetal head position by either one of the two methods was analyzed using the cumulative sums (CUSUM) method for measurement errors.ResultsOne hundred patients underwent digital vaginal examination and 99 had transabdominal sonography for the determination of fetal head position. An error rate of around 50% for vaginal examination was nearly constant during the first 50 examinations. It decreased subsequently, to stabilize at a low level from the 82nd patient. Errors of ± 180° were the most frequent. The learning curve for ultrasound imaging stabilized earlier than that of vaginal examination, after the 32nd patient. The most frequent errors with ultrasound examination were the inability to conclude on a diagnosis, particularly at the beginning of training, followed by errors of ± 45°.ConclusionsBased on our findings for the student tested, learning and accuracy of the determination of fetal head position in labor were easier and higher, respectively, with transabdominal sonography than with digital examination. This should encourage physicians to introduce clinical ultrasound examination into their practice. CUSUM charts provide a reliable representation of the learning curve, by accumulating evidence of performance. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Round ligament varices: sonographic appearance in pregnancy
Authors: McKenna D. A. , Carter J. T. , Poder L. , Gosnell J. E. , Maa J. , Pearl J. M. , Goldstein R. B. 
Published: February 2008

AbstractRound ligament varices (RLV) are an important clinical entity as they may cause hernia‐like symptoms in the absence of a true hernia. When this condition is diagnosed correctly, unnecessary intervention may be prevented. We aimed to determine the significance and anatomy of RLV in pregnancy and to review and describe their clinical and sonographic appearance. We followed prospectively five patients who presented during pregnancy with clinical symptoms suspicious of an inguinal hernia. All patients were diagnosed with RLV on ultrasound examination. All patients were managed conservatively and in all five cases, RLV resolved spontaneously postpartum. The diagnosis of RLV should be considered in pregnant women presenting with a groin mass. Sonography is diagnostic and can save unnecessary surgical exploration and associated morbidity. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Transposition of the great arteries in the fetus: assessment of the spatial relationships of the arterial trunks by four‐dimensional echocardiography
Authors: Paladini D. , Volpe P. , Sglavo G. , Vassallo M. , De Robertis V. , Marasini M. , Russo M. G. 
Published: February 2008

AbstractObjectiveCoronary arterial abnormalities can be one of the few negative prognostic indicators in transposition of the great arteries (TGA), and their occurrence is related to the type of spatial relationship of the great arteries. The main objective of this study was to assess whether the use of the reconstructed en‐face view with color Doppler imaging of the four cardiac valves can demonstrate the different types of spatial relationship of the arterial trunks in fetuses with TGA, in order to derive the risk of coronary abnormalities. A secondary end‐point was the evaluation of the type of coronary arterial branching pattern.MethodsTwenty‐three fetuses with a confirmed diagnosis of TGA underwent four‐dimensional (4D) echocardiography at 19–33 gestational weeks. The en‐face view of the four cardiac valves and color Doppler with high persistence were employed to assess the spatial relationships of the great arteries. In all cases, confirmation of the vessels' arrangement and coronary arterial distribution was obtained at neonatal echocardiography and/or surgery.ResultsThe spatial relationships of the great vessels was identified correctly in 20/23 (87%) cases. The aorta was found to be located anterior to and to the right of the pulmonary trunk in 13/23 (56.5%) cases and just anterior to the pulmonary artery in 6/23 (26.1%) cases; in the remaining four (17.4%) cases, the two vessels were side by side. With respect to the association between the spatial relationship of the great arteries and the occurrence of an unusual pattern of coronary arterial branching, five of the TGA fetuses had abnormal coronary arterial distribution.ConclusionsUsing 4D echocardiography with color Doppler, it is possible to define the spatial relationships of the great arteries in fetuses with TGA with a high degree of accuracy. This information can be used during counseling to predict the likelihood of abnormal coronary arterial distribution. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Nuclear microprobe studies of elemental distribution in mycorrhizal and non‐mycorrhizal roots of Ni‐hyperaccumulator Berkheya coddii
Authors: Orłowska E. , Mesjasz‐Przybyłowicz J. , Przybyłowicz W. , Turnau K. 
Published: February 2008

AbstractMicro–particle‐induced x‐ray emission (PIXE) was used to assess the influence of arbuscular mycorrhiza on the elemental concentration and distribution in roots of Berkheya coddii and to evaluate the role of fungal hyphae in elemental uptake by this plant. Analysis revealed a significant influence of mycorrhiza on the concentration and distribution of elements in roots of B. coddii. Mycorrhizal roots had significantly higher concentration of P, Ca, Zn and Cu than the non‐mycorrhizal ones. The mycorrhizal fungi also affected the distribution of elements (P, K, Cl, Zn and Ni) within the roots. The external fungal hyphae showed a high binding capacity of metals (Cu, Zn, and Ni). Matrix corrections done on the basis of simultaneous use of proton backscattering technique were essential due to the highly variable thickness of analyzed specimens. Copyright © 2008 John Wiley & Sons, Ltd.