bluuebunny/crossref_metadata_2025 huggingface dataset:
Equivalent resistance and noise of cascaded mesoscopic cavities
Authors: Macucci M. , Marconcini P. , Iannaccone G.
Published: April 2007

Since the time of the early studies on mesoscopic devices, it was recognized that, due mainly to the ballistic nature of transport, their resistances and the other electrical quantities could not be combined following the traditional rules of circuit theory. Here, we focus specifically on the conductance and noise resulting from a chain of cascaded mesoscopic cavities and discuss an existing semiclassical model for conductance and shot noise, recasting it into an equivalent circuit description. Numerical simulations show that such a model fails if the cavities are identical and is only partially valid if cavities are unequal. We discuss possible explanations for such a somewhat surprising behaviour. Copyright © 2007 John Wiley & Sons, Ltd.
Cover Picture: Ring Reversal of a Spirocyclic Patchouli Odorant: Molecular Modeling, Synthesis, and Odor of 6‐Hydroxy‐1,1,6‐trimethylspiro[4.5]decan‐7‐one (Eur. J. Org. Chem. 14/2007)
Authors: Kraft Philip , Bruneau Audrey
Published: April 2007

The cover picture shows shows the superposition of two spirocyclic target molecules, modeled on a recently discovered high‐impact patchouli odorant by ring‐reversal and structural simplification. Yet, despite omission of two methyl substituents, these sterically congested structures proved to be synthetically challenging targets. The synthesis of the first and principal target features a TiCl4‐mediated spiroannulation of the TMS‐enolate of cyclohexanone with 1‐bromo‐4‐chloro‐4‐methylpentane, subsequent dehydration by Appel–Lee bromination with concomitant dehydrohalogenation, and the elegant ketohydroxylation reaction of Plietker. Key odor descriptors for “patchouli” are “camphor”, “woody” and “earthy”, and depending on the molecular shape of the odorants, these are more or less balanced; the first target structure, for instance, is more shifted towards the camphoraceous, in principle an anti‐erogenous, attribute. Yet patchouli oil always had a sensual connotation, and since Indian girls ritually used to perfume their backs with patchouli oil to bewitch a lover, these molecules shine in front of a female back bearing their structural formulae in a lower backpiece fashion tattoo. The molecular design, synthesis and olfactory properties of these new odorants are discussed in the article by P. Kraft and A. Bruneau on p. 2257 ff.
Proteome analysis of the culture environment supporting undifferentiated mouse embryonic stem and germ cell growth
Authors: Buhr Nicolas , Carapito Christine , Schaeffer Christine , Hovasse Agnès , Van Dorsselaer Alain , Viville Stéphane
Published: April 2007

The therapeutical interest of pluripotent cells and ethical issues related to the establishment of human embryonic stem cell (ESC) or embryonic germ cell (EGC) lines raise the understanding of the mechanism underlying pluripotency to a fundamental issue. Establishing a protein pluripotency signature for these cells can be complicated by the presence of unrelated proteins produced by the culture environment. Here, we have analyzed the environment supporting ESC and EGC growth, and established 2‐D reference maps for each constituent present in this culture environment: mouse embryonic fibroblast feeder cells, culture medium (CM) and gelatin. The establishment of these reference maps is essential prior to the study of ESC and EGC specific proteomes. Indeed, these maps can be subtracted from ESC or EGC maps to allow focusing on spots specific for ESCs or EGCs. Our study led to the identification of 110 unique proteins from fibroblast feeder cells and 23 unique proteins from the CM, which represent major contaminants of ESC and EGC proteomes. For gelatin, no collagen‐specific proteins were identified, most likely due to difficulties in resolution and low quantities. Furthermore, no differences were observed between naive and conditioned CM. Finally, we compared these reference maps to ESC 2‐D gels and isolated 17 ESC specific spots. Among these spots, proteins that had already been identified in previous human and mouse ESC proteomes were identified but no apparent ESC‐specific pluripotency marker could be identified. This work represents an essential step in furthering the knowledge of environmental factors supporting ESC and EGC growth.
Entropy‐based equation to assess hillslope sediment production
Authors: Araújo José Carlos de
Published: April 2007

A new equation to assess hillslope sediment production, based on physical and probabilistic approaches, is presented. The equation, which allows the computation of the delivery ratio for every event, considers the physical variables of travel distance, stream power, settling velocity and gross erosion. The probability density function that arises from the new formulation is solved using the principle of maximum entropy. Based on data from five watersheds in both tropical and temperate zones, the new delivery parameter Kv is calibrated and associated with vegetation cover and conservation practice. The proposed equation is rationally based in relation to parameter Kv. The entropy‐based equation was applied to assess sediment yield in two other experimental watersheds, showing good predictability for the set (mean absolute error of 20·8%). No systematic error was found in the analysed data. The entropy‐based equation showed good predictability for long‐term sets of data and for high‐erosivity events, but did not perform well for the low‐erosivity ones. Copyright © 2007 John Wiley & Sons, Ltd.
Lattice Boltzmann methods for shallow water flow applications
Authors: Thömmes Guido , Seaïd Mohammed , Banda Mapundi K.
Published: April 2007

We apply the lattice Boltzmann (LB) method for solving the shallow water equations with source terms such as the bed slope and bed friction. Our aim is to use a simple and accurate representation of the source terms in order to simulate practical shallow water flows without relying on upwind discretization or Riemann problem solvers. We validate the algorithm on problems where analytical solutions are available. The numerical results are in good agreement with analytical solutions. Furthermore, we test the method on a practical problem by simulating mean flow in the Strait of Gibraltar. The main focus is to examine the performance of the LB method for complex geometries with irregular bathymetry. The results demonstrate its ability to capture the main flow features. Copyright © 2007 John Wiley & Sons, Ltd.
Thrombin potently enhances swelling‐sensitive glutamate efflux from cultured astrocytes
Authors: Ramos‐Mandujano Gerardo , Vázquez‐Juárez Erika , Hernández‐Benítez Reyna , Pasantes‐Morales Herminia
Published: April 2007

High concentrations of thrombin (Thr) have been linked to neuronal damage in cerebral ischemia and traumatic brain injury. In the present study we found that Thr markedly enhanced swelling‐activated efflux of 3H‐glutamate from cultured astrocytes exposed to hyposmotic medium. Thr (0.5–5 U/mL) elicited small 3H‐glutamate efflux under isosmotic conditions and increased the hyposmotic glutamate efflux by 5‐ to 10‐fold, the maximum effect being observed at 15% osmolarity reduction. These Thr effects involve its protease activity and are fully mimicked by SFFLRN, the synthetic peptide activating protease‐activated receptor‐1. Thr potentiation of 3H‐glutamate efflux was largely dependent on a Thr‐elicited increases in cytosolic Ca2+ (Ca2+i) concentration ([Ca2+]i). Preventing Ca2+i rise by treatment with EGTA‐AM or with the phospholipase C blocker U73122 reduced the Thr‐increased glutamate efflux by 68%. The protein kinase C blockers Go6976 or chelerythrine reduced the Thr effect by 19%–22%, while Ca/calmodulin blocker W7 caused a 63% inhibition. In addition to this Ca2+‐sensitive pathway, Thr effect on glutamate efflux also involved activation of phosphoinositide‐3 kinase (PI3K), since it was reduced by the PI3K inhibitor wortmannin (51% inhibition). Treating cells with EGTA‐AM plus wortmannin essentially abolished Thr‐dependent glutamate efflux. Thr‐activated glutamate release was potently inhibited by the blockers of the volume‐sensitive anion permeability pathway, NPPB (IC50 15.8 μM), DCPIB (IC50 4.2 μM). These results suggest that Thr may contribute to the excitotoxic neuronal injury by elevating extracellular glutamate release from glial cells. Therefore, this work may aid in search of neuroprotective strategies for treating cerebral ischemia and brain trauma. © 2007 Wiley‐Liss, Inc.
Contrasting potential of nitric oxide and peroxynitrite to mediate oligodendrocyte injury in multiple sclerosis
Authors: Jack Carolyn , Antel Jack , Brück Wolfgang , Kuhlmann Tanja
Published: April 2007

Nitric oxide (NO) and peroxynitrite (ONOO−) are potential mediators of the injury and cytotoxicity occurring over time to oligodendrocytes in multiple sclerosis (MS) lesions. Our in vitro results indicate that human adult CNS‐derived oligodendrocytes are relatively resistant to NO‐mediated damage. In contrast, human oligodendrocytes are highly susceptible to peroxynitrite‐mediated injury. In situ, we found that inducible nitric oxide synthase (iNOS) was expressed in astrocytes and macrophages in all active demyelinating and remyelinating MS lesions examined, yet no correlation was found between numbers of glial cells expressing iNOS and the extent of oligodendrocyte cell death. Nitrotyrosine groups, indicative of the presence of peroxynitrite in vivo, could be detected on astrocytes, macrophages, and oligodendrocytes in MS lesions. High numbers of nitrotyrosine‐positive oligodendrocytes were found in one MS case that featured extensive oligodendrocyte cell death. Our results indicate that NO alone is unlikely to induce oligodendrocyte injury, whereas its more potent byproduct peroxynitrite is a potential mediator of injury to oligodendrocytes in MS. © 2007 Wiley‐Liss, Inc.
The roles of aquaporin‐4 in brain edema following neonatal hypoxia ischemia and reoxygenation in a cultured rat astrocyte model
Authors: Fu Xuemei , Li Qiuping , Feng Zhichun , Mu Dezhi
Published: April 2007

Aquaporin‐4 (AQP4), a water channel protein, is abundantly expressed in astrocytes and plays a key role in the development of brain edema. However, it is not clear whether AQP4 contributes to astrocytic swelling in hypoxia–ischemia (HI). To investigate the roles of AQP4 in astrocytic swelling during HI and reoxygenation, we measured AQP4 expression and astrocytic cellular volume in cultured rat astrocytes following HI and reoxygenation. RNA interference was used to knockdown AQP4 expression (AQP4−/−). Real‐time polymerase chain reaction and Western blot analysis were used to detect the inhibitory efficiency of AQP4. We found that the maximal inhibition of AQP4 mRNA and protein in astrocytes after AQP4 siRNA transfection (AQP4−/−) was ∼77 and 85%, respectively, compared to wild‐type AQP4 (AQP4+/+) expression. Cellular volume in both AQP4−/− and AQP4+/+ astrocytes was significantly increased during HI compared to cells cultured in normoxia (P < 0.05). However, cellular volume during HI in AQP4−/− astrocytes was significantly less than that in AQP4+/+ astrocytes (P < 0.05). After reoxygenation, the cellular volume gradually decreased to control levels at 7 days in AQP4−/− but at 5 days in AQP4+/+ astrocytes. The different roles of AQP4 during HI and reoxygenation suggest that AQP4 knockdown may protect against water influx in the formation of astrocyte swelling during HI, and may also delay water clearance in the resolution of astrocyte swelling during reoxygenation. In conclusion, AQP4 mediates bidirectional transport of water across astrocytes during HI and reoxygenation. AQP4 manipulation may serve as a novel therapeutic strategy during different periods of hypoxic–ischemic brain edema in neonates. © 2007 Wiley‐Liss, Inc.
Functional organization of human visual cortex in occipital polymicrogyria
Authors: Dumoulin Serge O. , Jirsch Jeffrey D. , Bernasconi Andrea
Published: April 2007

Polymicrogyrias (PMG) are cortical malformations resulting from developmental abnormalities. In animal models PMG has been associated with abnormal anatomy, function, and organization. The purpose of this study was to describe the function and organization of human polymicrogyric cortex using functional magnetic resonance imaging. Three patients with epilepsy and bilateral parasagittal occipital polymicrogyri were studied. They all had normal vision as tested by Humphrey visual field perimetry. The functional organization of the visual cortex was reconstructed using phase‐encoded retinotopic mapping analysis. This method sequentially stimulates each point in the visual field along the axes of a polar‐coordinate system, thereby reconstructing the representation of the visual field on the cortex. We found normal cortical responses and organization of early visual areas (V1, V2, and V3/VP). The locations of these visual areas overlapped substantially with the PMG. In five out of six hemispheres the reconstructed primary visual cortex completely fell within polymicrogyric areas. Our results suggest that human polymicrogyric cortex is not only organized in a normal fashion, but is also actively involved in processing of visual information and contributes to normal visual perception. Hum Brain Mapp 2007. © 2007 Wiley‐Liss, Inc.
Individual variation in neural correlates of sadness in children: A twin fMRI study
Authors: Côté Catherine , Beauregard Mario , Girard Alain , Mensour Boualem , Mancini‐Marïe Adham , Pérusse Daniel
Published: April 2007

Functional neuroimaging studies show substantial individual variation in brain activation accompanying the experience of emotion, including sadness. Here we used functional magnetic resonance imaging (fMRI) in 104 pairs of 8‐year‐old twins (47 MZ, 57 DZ) to assess genetic‐environmental contributions to individual differences in neural activation in two prefrontal cortex (PFC) areas previously shown to be involved in sadness. No genetic effects were found for any area, individual environmental factors entirely accounting for individual variation in brain activation related to sadness. Sadness being the prevailing mood in depression, these findings may be of relevance to the etiology of childhood depressive disorders. Hum Brain Mapp 2007. © 2007 Wiley‐Liss, Inc.
Cortical mapping of genotype–phenotype relationships in schizophrenia
Authors: Bearden Carrie E. , van Erp Theo G.M. , Thompson Paul M. , Toga Arthur W. , Cannon Tyrone D.
Published: April 2007

Although schizophrenia is highly heritable, the search for susceptibility genes has been challenging. The “endophenotype” approach is an alternative method for measuring phenotypic variation that may make it easier to identify susceptibility genes in the context of complexly inherited traits. Neuroimaging methods in particular offer a powerful way to bridge the neurobiology of genes and behavior. Such investigations may be further empowered by complementary strategies involving chromosomal abnormalities associated with schizophrenia, which can help to localize causative genes and better understand the genetic complexity of the illness. Here, we illustrate our use of these convergent approaches, with a focus on neuroimaging studies using novel computational brain mapping algorithms, to investigate genetic influences on brain structure in the development of psychosis. These studies provide compelling evidence that specific genetic loci suspected to predispose to schizophrenia may affect quantitative variation in neural indicators underlying the neurobehavioral phenotype, and illustrate how genetic‐neuroimaging paradigms can improve our understanding of the pathogenesis of this highly disabling mental illness. Hum Brain Mapp, 2007. © 2007 Wiley‐Liss, Inc.
Cervical screening by visual inspection, HPV testing, liquid‐based and conventional cytology in Amazonian Peru
Authors: Almonte Maribel , Ferreccio Catterina , Winkler Jennifer L. , Cuzick Jack , Tsu Vivien , Robles Sylvia , Takahashi Rina , Sasieni Peter
Published: April 2007

Cervical cancer is an important public health problem in many developing countries, where cytology screening has been ineffective. We compared four tests to identify the most appropriate for screening in countries with limited resources. Nineteen midwives screened 5,435 women with visual inspection (VIA) and collected cervical samples for HPV testing, liquid‐based cytology (LBC) and conventional cytology (CC). If VIA was positive, a doctor performed magnified VIA. CC was read locally, LBC was read in Lima and HPV testing was done in London. Women with a positive screening test were offered colposcopy or cryotherapy (with biopsy). Inadequacy rates were 5% and 11% for LBC and CC respectively, and less than 0.1% for VIA and HPV. One thousand eight hundred eighty‐one women (84% of 2,236) accepted colposcopy/cryotherapy: 79 had carcinoma in situ or cancer (CIS+), 27 had severe‐ and 42 moderate‐dysplasia on histology. We estimated a further 6.5 cases of CIS+ in women without a biopsy. Sensitivity for CIS+ (specificity for less than moderate dysplasia) was 41.2% (76.7%) for VIA, 95.8% (89.3%) for HPV, 80.3% (83.7%) for LBC, and 42.5% (98.7%) for CC. Sensitivities for moderate dysplasia or worse were better for VIA (54.9%) and less favourable for HPV and cytology. In this setting, VIA and CC missed the majority of high‐grade disease. Overall, HPV testing performed best. VIA gives immediate results, but will require investment in regular training and supervision. Further work is needed to determine whether screened‐positive women should all be treated or triaged with a more specific test. © 2007 Wiley‐Liss, Inc.
Dynamic factor extraction of cross‐sectional dependence in panel unit root tests
Authors: Kapetanios George
Published: April 2007

Recently, considerable emphasis has been placed on the problems arising out of cross‐sectional dependence in panel unit root tests. This paper adopts the factor‐based cross‐sectional dependence paradigm of Bai and Ng (2005) but suggests alternative factor extraction methods. Some theoretical results for these methods are provided. Further, a detailed Monte Carlo study of these methods for multiple and persistent factors is undertaken. It is found that results are radically different from the serially uncorrelated single‐factor case. Tests perform much worse and in some cases it is preferable not to correct at all for cross‐sectional dependence. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of calcium ion‐implantation of titanium on bone cell function in vitro
Authors: Nayab Saima N. , Jones Frances H. , Olsen Irwin
Published: April 2007

The modification of titanium (Ti) surfaces by ion‐implantation has previously been reported to enhance osseointegration in vivo. However, the mechanisms underlying the apparently improved biocompatibility of these novel implant materials are unknown. The aim of this study is, therefore, to determine the precise effects of calcium ion‐implanted Ti on the functional activity of bone cells in vitro. Flow cytometry (FCM) and the reverse transcriptase polymerase chain reaction (RT‐PCR) were used to measure the response of bone‐derived cells to key bone‐associated components, including alkaline phosphatase (ALP), bone morphogenetic protein receptor‐1B (BMPR‐1B), bone sialoprotein (BSP), osteonectin (ON), and osteopontin (OPN). FCM analysis showed that BMPR‐1B, BSP and particularly OPN were significantly up‐regulated in MG‐63 cells cultured on Ca‐implanted Ti compared with control nonimplanted Ti. Moreover, the effects of this novel Ca–Ti surface were found to be mediated, at least partly, via gene activation, since RT‐PCR demonstrated the presence of notably elevated levels of OPN mRNA transcripts in the MG‐63 cells. These findings thus show that Ti surfaces implanted with Ca ions can enhance the expression of certain bone‐associated components in vitro, and suggest that this effect could be the cause of the potential benefit of this material on bone in vivo. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Mechanical stimulation of TMJ condylar chondrocytes encapsulated in PEG hydrogels
Authors: Nicodemus Garret D. , Villanueva Idalis , Bryant Stephanie J.
Published: April 2007

Temporomandibular joint (TMJ) disorders are most commonly associated with TMJ disc dislocation and osteoarthritis, which can cause erosion of the articular cartilage on the head of the mandibular condyle. There has been little attention focused on treating the damaged condylar cartilage. Therefore, the overall goal of this research is to create a tissue engineering therapy for resurfacing the damaged cartilage of the condylar process with healthy living tissue. Initially, bovine condylar cartilage explants were studied to understand the tissue structure, composition, and gene expression of the native tissue. The cell response of isolated condylar chondrocytes encapsulated in photopolymerized poly(ethylene glycol) hydrogels as a tissue engineering scaffold was examined in the presence and absence of dynamic loading for up to three days of culture. Condylar chondrocyte viability was maintained within the PEG hydrogel constructs over the culture period and loading conditions. Cell response was examined through real‐time RTPCR for collagen types I and II and aggrecan, nitric oxide production, cell proliferation, proteoglycan (PG) synthesis, and spatial distribution of extracellular matrix through histology. This study demonstrates that PEG hydrogel constructs are suitable for condylar chondrocyte encapsulation in the absence of loading. However, dynamic compressive strains resulted in inhibition of gene expression, cell proliferation, and PG synthesis. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Regulation of the pyrimidine biosynthetic pathway in a pyrD knockout mutant of Pseudomonas aeruginosa
Authors: Ralli Pooja , Srivastava Avinash C. , O'Donovan Gerard
Published: April 2007

In research to date, regulation of the pyrimidine biosynthetic pathway at the level of gene expression has not been shown for wild type Pseudomonas aeruginosa. No repression was observed when uracil was added to the growth medium nor was any derepression seen when Pyr– auxotrophs were limited for pyrimidines. Here we show that the addition of uracil to Pseudomonas minimal medium influenced the synthesis of pyrimidine enzymes, while starvation of a pyrimidine knockout mutant (pyrD) elicited derepression of the pyrimidine enzymes. Moreover, the inclusion of orotate in the growth medium induced the synthesis of dihydroorotase in both wild type and mutant. These results suggest that the pyrimidine pathway in P. aeruginosa is regulated at the level of enzyme synthesis in a manner similar to a number of other Pseudomonas species. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ermittlung von Umformgrenzen beim Freiformschmieden
Authors: Schneider V. , Hirt G. , Brethfeld A. , Lehmann G. , Diener U.
Published: April 2007

Im Rahmen des von der Arbeitsgemeinschaft industrieller Forschungsvereinigungen (AiF) geförderten Vorhabens „Vermeidung von Oberflächenfehlern beim Freiformschmieden”︁ wurden die umformtechnischen Einflüsse auf die Rissentstehung beim Freiformschmieden untersucht. Dafür standen Gussblöcke zweier hochlegierter Stähle (1.2367 und 1.6957) aus der industriellen Produktion zur Verfügung.

Das Umformverhalten beider Stähle wurde durch Stauch‐, Zug‐ und Torsionsversuche für den gesamten Warmumformbereich der Industrieschmiedeprozesse charakterisiert. Dabei zeigte sich, dass der Ort der Probenentnahme bei den vorliegenden Blockabmessungen einen geringen Einfluss auf das Umformverhalten der Werkstoffe hat. Des Weiteren sind Untersuchungen zum Umwandlungs‐ und Ausscheidungsverhalten beider Stähle sowie metallografische Untersuchungen durchgeführt worden. Damit sollte die Ursache für Streuungen von Messwerten im unteren Temperaturbereich der Warmumformung ermittelt werden.

Anhand von Stauchversuchen mit Schallemissionsanalyse und deren nummerischer Simulation wurden Rissgrenzschaubilder für den in den Industrieschmiedungen ermittelten risskritischen Umformbereich erstellt. Mit deren Hilfe konnten Umformgrenzen für Laborschmiedeversuche bestimmt werden. Bei den Stauchversuchen mit beiden Werkstoffen streuten die durch Schallemissionsanalyse ermittelten Zeitpunkte, bei denen es zum Rissauftritt an den Proben kam, sehr stark. Daher konnte keine eindeutige Umformgrenze in Form einer zulässigen Höhenabnahme bestimmt werden. Stattdessen wurden für die risskritischen Temperaturen beider Stähle die jeweilige maximal zulässige Höhenabnahme bestimmt, die in Laborschmiedeversuchen unter industrienahen Bedingungen überprüft wurde. Es zeigte sich, dass die ermittelten Grenzen sehr sicher sind, da es zu keinem Rissauftritt während der Schmiedungen beider Werkstoffe kam.
Modeling of Transient Thermal Contact Resistance out of Conjugate Gradient Method
Authors: El‐Sabbagh A.M. , Fieberg C. , El‐Magd E. , Kneer R.
Published: April 2007

Temperature profile at contacting pairs of any material combination is crucial in many engineering applications. A new experimental approach is suggested to estimate the contact heat transfer coefficient as well as the thermal contact resistance. This method is based on temperature infrared measurements of contact bodies and then solve the inverse problem with conjugate gradient method. Different affecting parameters are studied namely; surface roughness, presence of interlayer, applied pressure and bodies temperature difference. The time dependant heat transfer coefficients resulting from the proposed method need to be validated by a computer model. Close results are shown with slight deviation by the increase of the applied pressure and the temperature difference.
Die Werkstoffbeanspruchung im Wälzkontakt bei hoher Flächenpressung, ermittelt nach Hertz und nach der EHD‐Strömungshypothese
Authors: Schlicht H. , Broszeit E.
Published: April 2007

Zur Berechnung der Werkstoffbeanspruchung im Wälzkontakt werden üblicherweise eine Hertz`sche Verteilung der Normalspannungen sowie Tangentialspannungen in der Kontaktfläche angenommen, die den Normalspannungen proportional sind. Diese numerische Beschreibung liegt der Lebensdauerberechnung von Wälzlagern zugrunde.

Geht man von den wirklichen Kräfteverteilungen im EHD‐Kontakt aus, so lässt sich mittels der EHD‐Strömungshypothese darlegen, dass in manchen Beanspruchungsfällen die tatsächliche Werkstoffbeanspruchung höher ist.
Multiplicity editing including quaternary carbons: improved performance for the 13C‐DEPTQ pulse sequence
Authors: Bigler Peter , Kümmerle Rainer , Bermel Wolfgang
Published: April 2007

An improved version of the DEPTQ experiment yielding the signal and multiplicity information for all carbon types including the signals of quaternary carbons is proposed. It encompasses all the known advantages of the basic DEPT experiment. In comparison to the original version, signals of the sensitivity‐limiting quaternary carbons are markedly increased: the initial 13C pulse may be adjusted to the Ernst angle, the NOE build‐up period is prolonged by the split relaxation delay and a partial recovery of signal losses due to instrumental imperfections is achieved by the incorporation of composite adiabatic 13C refocussing pulses. Furthermore, pure absorption lineshapes for all carbon types are obtained with only one single scan. These attributes make this experiment attractive for 13C analysis of small molecules (including spectral editing), particularly in high‐throughput analysis laboratories. Copyright © 2007 John Wiley & Sons, Ltd.
The role of multiple drug resistance proteins in fetal and/or placental protection against teratogen‐induced orofacial clefting
Authors: Rawles Lesli Ann , Acuna Diana , Erickson Robert P.
Published: April 2007

Previous studies have shown a role for multiple drug resistance proteins in protecting the fetus from a limited number of teratogens. We have expanded the number of proteins and teratogens examined by comparing the influence of the mdr1a and mdr2 proteins on teratogen‐induced orofacial clefting using their respective knockouts in crosses with the A/J, high susceptibility strain. Western blots identified the presence of mdr1a and possibly mdr2 in the placenta and fetus. Themdr1aknockout, on its unique genetic background showed lower, similar, and higher incidences of clefting compared to A/J for Dilantin, hydrocortisone (HC), and 6‐aminonicotinamide (6‐AN), respectively. Themdr2knockout did not affect 6‐AN clefting when compared to A/J. In reciprocal crosses, when corrected for increased spontaneous clefting, maternally inherited A/J susceptibility genes predominated over the effects of the maternal absence of mdr1a (with 6‐AN). Unlike mdr1a, which had a direct effect in the fetus as shown by genotyping of affected versus unaffected fetuses, an effect of mdr2 in the fetus was not found. Themdr1aknockout was backcrossed to the A/J inbred strain for 11 generations (congenics) to eliminate genetic background effects. Reciprocal crosses showed no maternal effect from the lack ofmdr1a, confirming that mdr1a expression in the fetus, rather than the placenta, protects the fetus from teratogens. Mdr2 seems not to be involved in the protection of the fetus from teratogens. Mol. Reprod. Dev. 74: 1483–1489, 2007. © 2007 Wiley‐Liss, Inc.
Inapproximability results for the inverse shortest paths problem with integer lengths and unique shortest paths
Authors: Bley Andreas
Published: April 2007

We study the complexity of two inverse shortest paths (ISP) problems with integer arc lengths and the requirement for uniquely determined shortest paths. Given a collection of paths in a directed graph D = (V, A), the task is to find positive integer arc lengths such that the given paths are uniquely determined shortest paths between their respective terminals. In the first problem we seek for arc lengths that minimize the length of the longest of the prescribed paths. In the second problem, the length of the longest arc is to be minimized. We show that it is 𝒩𝒫‐hard to approximate the minimal longest path length within a factor less than 8/7 or the minimal longest arc length within a factor less than 9/8. This answers the (previously) open question whether these problems are 𝒩𝒫‐hard or not. We also present a simple algorithm that achieves an 𝒪(∣V∣)‐approximation guarantee for both variants. Both ISP problems arise in the planning of telecommunication networks with shortest path routing protocols. Our results imply that it is 𝒩𝒫‐hard to decide whether a given path set can be realized with a real shortest path routing protocol such as OSPF, IS‐IS, or RIP. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 29–36 2007
Hardness of robust network design
Authors: Chekuri C. , Shepherd F.B. , Oriolo G. , Scutellá M.G.
Published: April 2007

The authors settle the complexity status of the robust network design problem in undirected graphs. The fact that the flow‐cut gap in general graphs can be large, poses some difficulty in establishing a hardness result. Instead, the authors introduce a single‐source version of the problem where the flow‐cut gap is known to be one. They then show that this restricted problem is coNP‐Hard. This version also captures, as special cases, the fractional relaxations of several problems including the spanning tree problem, the Steiner tree problem, and the shortest path problem. © 2007 Wiley Periodicals, Inc. NETWORKS, Vol. 50(1), 50–54 2007
A cut‐cell non‐conforming Cartesian mesh method for compressible and incompressible flow
Authors: Pattinson J. , Malan A. G. , Meyer J. P.
Published: April 2007

This paper details a multigrid‐accelerated cut‐cell non‐conforming Cartesian mesh methodology for the modelling of inviscid compressible and incompressible flow. This is done via a single equation set that describes sub‐, trans‐, and supersonic flows. Cut‐cell technology is developed to furnish body‐fitted meshes with an overlapping mesh as starting point, and in a manner which is insensitive to surface definition inconsistencies. Spatial discretization is effected via an edge‐based vertex‐centred finite volume method. An alternative dual‐mesh construction strategy, similar to the cell‐centred method, is developed. Incompressibility is dealt with via an artificial compressibility algorithm, and stabilization achieved with artificial dissipation. In compressible flow, shocks are captured via pressure switch‐activated upwinding. The solution process is accelerated with full approximation storage (FAS) multigrid where coarse meshes are generated automatically via a volume agglomeration methodology. This is the first time that the proposed discretization and solution methods are employed to solve a single compressible–incompressible equation set on cut‐cell Cartesian meshes. The developed technology is validated by numerical experiments. The standard discretization and alternative methods were found equivalent in accuracy and computational cost. The multigrid implementation achieved decreases in CPU time of up to one order of magnitude. Copyright © 2007 John Wiley & Sons, Ltd.
Graft versus leukemia effect against juvenile myelomonocytic leukemia after unrelated cord blood transplantation
Authors: Tanoshima Reo , Goto Hiroaki , Yanagimachi Masakatsu , Kajiwara Ryosuke , Kuroki Fumiko , Yokota Shumpei
Published: April 2007

A 13‐month‐old female underwent unrelated cord blood transplantation (CBT) for juvenile myelomonocytic leukemia (JMML). In spite of progression of the disease after a conditioning regimen with high‐dose chemotherapy, a complete remission was induced in concordance with development of acute GVHD after reduction of the immunosupressant. She has been in complete remission for 1 year after transplantation. This case illustrates that CBT can provide a potent graft versus leukemia (GVL) effect against JMML. Pediatr Blood Cancer 2008;50:665–667. © 2007 Wiley‐Liss, Inc.
Depressive symptoms and SSRI use in pediatric oncology patients
Authors: Kersun Leslie S. , Elia Josephine
Published: April 2007

This review of depressive symptoms in pediatric cancer patients describes the challenge of recognizing depression in this group, prevalence, risk factors, and treatment, primarily with the selective serotonin reuptake inhibitors (SSRIs). Pediatric oncologists prescribe SSRIs, but there is limited data regarding their use in this setting. Adverse effects, pharmacokinetics and metabolism of SSRIs are reviewed to provide a reference for physicians and inform choices for SSRI prescription. Ongoing research includes incorporation of routine screening measures for depression and future studies might focus on physician recognition and prospectively evaluating treatment for children with cancer and depressive symptoms. Pediatr Blood Cancer 2007;49:881–887. © 2007 Wiley‐Liss, Inc.
The role of academia and the research community in assisting the food and drug administration to ensure U.S. drug safety
Authors: Re Vincent Lo , Strom Brian L.
Published: April 2007

Purpose

Academia can play a prominent role in the drug safety arena, unique from that of industry, and a clearer articulation of how it could positively influence the current system is needed. We sought to examine ways that academia could expand its role in U.S. drug safety.

Methods

An ad hoc meeting of academic experts in drug safety and risk management was convened at the Institute of Medicine (IOM) in Washington, D.C.

Results

Academia should develop a stronger partnership with the Food and Drug Administration (FDA) to increase research on regulatory issues and public health questions and facilitate the prioritization of critical issues on drug safety. Such a collaboration could also facilitate the development of a network of academic centers of excellence in pharmacoepidemiology to address drug safety and risk management questions from a public health standpoint in a timely fashion. The development and testing of methodologic innovations on drug safety should also be encouraged.

Conclusions

Greater partnership between academia and the FDA could facilitate the prioritization of important issues on drug safety, allow more research questions on drug safety to be answered in a timely fashion, promote the development of networks for answering these questions, and help generate additional research ideas, ultimately providing enormous benefit to the public health. Copyright © 2007 John Wiley & Sons, Ltd.
Report of resistance to the neonicotinoid insecticide imidacloprid in Trialeurodes vaporariorum (Hemiptera: Aleyrodidae)
Authors: Gorman Kevin , Devine Gregor , Bennison Jude , Coussons Peter , Punchard Neville , Denholm Ian
Published: April 2007

Susceptibilities of UK and mainland European samples of Trialeurodes vaporariorum (Westwood) to the neonicotinoid insecticide imidacloprid were investigated over a 7 year period. All 24 strains collected between 1997 and 2003 showed similar baseline levels of susceptibility to that of a known susceptible laboratory strain when exposed to a diagnostic concentration (128 mg L−1) of formulated imidacloprid. Two samples collected during 2004, one from the UK and one from The Netherlands, demonstrated reduced susceptibility at this concentration. Using dose–response assays, the presence of resistant individuals was disclosed in both these strains; some individuals were unaffected at doses high enough to induce phytotoxic effects. This report represents the first confirmed cases of neonicotinoid resistance inducing control failures in T. vaporariorum, and highlights a need for careful vigilance to sustain the effectiveness of imidacloprid and related neonicotinoid insecticides. Copyright © 2007 Society of Chemical Industry
Impact of a Turkish isolate and a plaque‐purified variant of SpliNPV‐B on larval stage development ofSpodoptera littoralis(Lepidoptera: Noctuidae) Boisd
Authors: Toprak Umut , Gürkan M Oktay , Bayram Şerife
Published: April 2007

Baculoviruses can alter the development and physiological status of their insect hosts. In the present study, twoSpodoptera littoralisnucleopolyhedroviruses (SpliNPV‐TR1 and SpliNPV‐M2) were examined in terms of their effect on the stage development ofS. littoralisat two doses/concentrations by inoculation of neonates or third instars. Both isolates had an acute pathological effect on neonates. However, larval development was prolonged (6–36 h) by either infection when neonates were infected. When third‐instar larvae were inoculated, no mortality occurred until insects moulted to later stages. When the isolates were compared, more mortality occurred in the fifth instar with SpliNPV‐M2 than with SpliNPV‐TR1, whereas less mortality occurred in the sixth instar with SpliNPV‐M2 than with SpliNPV‐TR1. However, none of the isolates demonstrated a dose effect. Larvae died at 108–198 h post‐inoculation at all infections, and none of them pupated. Larval development was retarded (0–126 h) for each stage when third‐instar larvae were inoculated. Consequently, SpliNPV‐M2 would be a more effective control agent than SpliNPV‐TR1 for control ofS. littoralissince it kills larvae at earlier developmental stages. Copyright © 2007 Society of Chemical Industry
The use of Fmoc‐Lys(Pac)‐OH and penicillin G acylase in the preparation of novel semisynthetic insulin analogs
Authors: Žáková Lenka , Zyka Daniel , Ježek Jan , Hančlová Ivona , Šanda Miloslav , Brzozowski Andrzej M. , Jiráček Jiří
Published: April 2007

In this paper, we present the detailed synthetic protocol and characterization of Fmoc‐Lys(Pac)‐OH, its use for the preparation of octapeptides H‐Gly‐Phe‐Tyr‐N‐MePhe‐Thr‐Lys(Pac)‐Pro‐Thr‐OH and H‐Gly‐Phe‐Phe‐His‐Thr‐Pro‐Lys(Pac)‐Thr‐OH by solid‐phase synthesis, trypsin‐catalyzed condensation of these octapeptides with desoctapeptide(B23‐B30)‐insulin, and penicillin G acylase catalyzed cleavage of phenylacetyl (Pac) group fromNε‐amino group of lysine to give novel insulin analogs [TyrB25,N‐MePheB26,LysB28,ProB29]‐insulin and [HisB26]‐insulin. These new analogs display 4 and 78% binding affinity respectively to insulin receptor in rat adipose membranes. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Activity and stability of human kallikrein‐2‐specific linear and cyclic peptide inhibitors
Authors: Pakkala Miikka , Hekim Can , Soininen Pasi , Leinonen Jari , Koistinen Hannu , Weisell Janne , Stenman Ulf‐HÅkan , Vepsäläinen Jouko , Närvänen Ale
Published: April 2007

Human glandular kallikrein (KLK2) is a highly prostate‐specific serine protease, which is mainly excreted into the seminal fluid, but part of which is also secreted into circulation from prostatic tumors. Since the expression level of KLK2 is elevated in aggressive tumors and it has been suggested to mediate the metastasis of prostate cancer, inhibition of the proteolytic activity of KLK2 is of potential therapeutic value. We have previously identified several KLK2‐specific linear peptides by phage display technology. Two of its synthetic analogs, A R R P A P A P G (KLK2a) and G A A R F K V W W A A G (KLK2b), show specific inhibition of KLK2 but their sensitivity to proteolysis in vivo may restrict their potential use as therapeutic agents. In order to improve the stability of the linear peptides for in vivo use, we have prepared cyclic analogs and compared their biological activity and their structural stability. A series of cyclic variants with cysteine bridges were synthesized. Cyclization inactivated one peptide (KLK2a) and its derivatives, while the other peptide (KLK2b) and its derivatives remained active. Furthermore, backbone cyclization of KLK2b improved significantly the resistance against proteolysis by trypsin and human plasma. Nuclear magnetic resonance studies showed that cyclization of the KLK2b peptides does not make the structures more rigid. In conclusion, we have shown that backbone cyclization of KLK2 inhibitory peptides can be used to increase stability without losing biological activity. This should render the peptides more useful for in vivo applications, such as tumor imaging and prostate cancer targeting. Copyright © 2007 European Peptide Society and John Wiley & Sons, Ltd.
Urbach tail in the absorption spectra of 2H‐WSe2 layered crystals
Authors: Hu S. Y. , Lee Y. C. , Shen J. L. , Chen K. W. , Huang Y. S.
Published: April 2007

Urbach's rule and steepness parameter of 2H‐WSe2 layered crystals have been studied via the absorption spectra from the photoconductivity (PC) measurements in the temperature range of 15–300 K. From the analysis of the temperature‐dependent band gap with Varshni semi‐empirical equation, the Debye temperature was estimated as 160 K while the Einstein temperature was around 125 K from the Einstein oscillator model. The effective phonon energy was estimated successfully from the temperature dependence of the Urbach energy extracted from the PC spectra and the value was found out to be well correlated to the active E1g mode observed in the Raman spectra of 2H‐WSe2. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optical and micro‐analytical study of a copper–conjugated polymer composite
Authors: Mallick Kaushik , Witcomb Mike J. , Scurrell Mike S.
Published: April 2007

An oriented morphology of a conjugated polymer has been synthesized by using cupric sulfate as the oxidizing agent. A one pot, in‐situ chemical synthesis approach has been utilized in which cupric sulfate is reduced during the polymerization process and forms copper nanoparticles, which are evenly dispersed in the polymer fiber. The elemental identity of the nanoparticles was determined by means of EDX analyses and EELS mapping for the copper using analytical transmission electron microscopy (TEM). The TEM images at higher magnifications showed that the copper particles were highly dispersed throughout the polymer matrix. Optical properties of the polymer were studied by UV–vis, Infrared and Raman spectra analysis and provided information regarding the chemical structure of the polymer. A brief mechanistic approach regarding the formation of the fiber‐like metal‐polymer composite material is given. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nano‐ and macropores in the model for current oscillations at the Si/electrolyte contact
Authors: Grzanna J. , Jungblut H. , Lewerenz H. J.
Published: April 2007

The transition from sustained to damped current oscillations or to stationary behavior is described using a model based on morphological aspects. A roughening of the oxide and of the underlying Si surface is predicted, in accordance with measurements. The role of cracks and nanopores in silicon oxide is discussed with regard to roughness increase and macropore formation. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrochemical formation of porous silica: toward an understanding of the mechanisms
Authors: Frey S. , Keipert S. , Chazalviel J.‐N. , Ozanam F. , Carstensen J. , Föll H.
Published: April 2007

Porous silica may be formed by anodization of silicon in a neutral fluoride electrolyte. Applying a high potential leads to initiation of porous layer growth, which may be pursued at lower potentials. We have tried to improve our understanding of the growth process. Initiation of the growth appears to be caused by oxygen evolution, which leads to local acidification of the medium. In the steady state, ion depletion in the electrolyte may lead to the presence of a strong space charge. Experiments indicate that such a charged layer may represent at most a small fraction of the porous layer thickness. Theoretical estimates suggest that this effect may be neglected. A model, making use of the diffusion equations of the various species (H+, F–, HF, SiF62–), accounts for the current/potential curves and oxide layer thickness in a semiquantitative manner. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoelectrochemical texturization of n‐type multicrystalline silicon
Authors: Tena‐Zaera R. , Bastide S. , Lévy‐Clément C.
Published: April 2007

Taking advantage of the electrochemical formation of macropores in aqueous HF under illumination, we have developed an efficient photoelectrochemical (PEC) texturization on n‐type multicrystalline Si (mc‐Si) wafers which leads to a decrease in the reflectivity of solar cells. An optimized mc‐Si texturized surface exhibits an 8.5% effective reflectivity (λ = 400–1000 nm, AM1.5 standard solar illumination). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaleable synthesis route for silicon nanocrystal assemblies
Authors: Limaye S. , Subramanian S. , Goller B. , Diener J. , Kovalev D.
Published: April 2007

We report on a scaleable synthesis route for highly luminescent silicon nanocrystal assemblies and demonstrate that their emission properties are identical to those known for other systems containing silicon nanocrystals. Structural investigations confirmed that chemically porosified metallurgical grade silicon powder consists of silicon nanocrystal assemblies having nanometer sizes characterized by very high total internal surface area. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis and photoluminescence properties of silicon nanowires treated by high‐pressure water vapor annealing
Authors: Salhi B. , Gelloz B. , Koshida N. , Patriarche G. , Boukherroub R.
Published: April 2007

This paper reports on silicon nanowires (SiNWs) growth on porous silicon (PS) template using vapor‐liquid‐solid (VLS) technique and the effect of high‐pressure water vapor annealing (HWA) on their optical properties. Gold nanoparticles (Au NPs) with average mean diameter of 50 and 20 nm were used as catalysts. The SiNWs were obtained by thermal decomposition of silane gas (SiH4) at high temperature (540 °C) catalyzed by the Au NPs. The resulting nanostructures display comparable diameter to the initial gold catalysts and are few microns long without a preferential growth direction. We have next examined the optical properties of the 20 nm diameter SiNWs. As‐prepared SiNWs display a weak photoluminescence (PL), which is related to the recombination emissions from defect centers. High‐pressure water vapor annealing (HWA) at 260 °C and 2.6 MPa of the SiNWs led to an increase of the PL by a factor 10 without significant changes in the emission band. TEM analysis of the HWA‐treated SiNWs showed a crystalline silicon core surrounded by an amorphous oxide layer. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)