bluuebunny/crossref_metadata_2025 huggingface dataset:
Eosinophilic perimyositis as the presenting feature of a monoclonal T‐cell expansion
Authors: Dunand Murielle , Lobrinus Johannes A. , Spertini Olivier , Kuntzer Thierry
Published: March 2005

A 51‐year‐old physically active man was investigated for exertional myalgias and muscle stiffness. On examination he had mild proximal muscle weakness of the upper extremities and retraction of the digit flexors. Blood eosinophilia was present, but serum creatine kinase (CK) levels and an electromyographic study were normal. A skin–fascia–muscle biopsy of the calf revealed a macrophagic and CD4+T‐cell infiltration of the perimysium, and a T‐cell expansion was observed in blood, bone marrow, and muscle. A diagnosis of eosinophilic perimyositis was made, and prednisone and azathioprine were administrated with a good clinical response. This case highlights the differential diagnosis of blood eosinophilia with muscle disorders, and underscores that eosinophilic perimyositis may be the expression of a T‐cell monoclonal expansion. Although the pathogenesis behind the T‐cell expansion is unclear but probably inflammatory, we suggest regular follow‐up to allow early treatment of any T‐cell lymphoproliferative malignancy that may develop. Muscle Nerve, 2005
Predictors of outcome in children with Langerhans cell histiocytosis
Authors: Jubran Rima F. , Marachelian Araz , Dorey Frederick , Malogolowkin Marcio
Published: March 2005

Background

Our goal was to examine the clinical course of patients with Langerhans cell histiocytosis (LCH), with a special emphasis on bone disease and to attempt to identify and examine the factors that may predict reactivation and overall prognosis.

Procedure

We conducted a retrospective chart review of 132 consecutive pediatric patients treated at Children's Hospital Los Angeles for LCH from 1984 to 2001.

Results

The risk for reactivation after initial management is significantly higher for patients with multiple bone and those with multiple organ involvement as compared with patients who had a single bone lesion (hazard ratios are 7.1 and 11.6). Patients younger than 1 year in the multiple organ group have an increased risk of death at 2 years when compared with the older patients in that group (hazard ration = 6.2, P = 0.022). Endocrine abnormalities were seen in 20% and 7.5% of patients with or without skull lesions respectively.

Conclusions

Patients with LCH involving only the bones have a significantly better outcome than those with other organ involvement. Patients with multiple organ involvement who are less than 1 year of age are at high risk of death and should be approached more aggressively upfront. Pediatr Blood Cancer 2005; 45:37–42. © 2005 Wiley‐Liss, Inc.
Synthesis of platinum‐terminated dendritic carbosilane
Authors: Li Chun‐Fang , Li Dong‐Xiang , Feng Sheng‐Yu
Published: March 2005

Carbosilane dendrimers with peripheral allyl groups were synthesized from methyltrichlorosilane, allyl chloride and magnesium, and were then functionalized by binding aminopropyl groups. Periphery platinated complexes were synthesized from chloroplatinic acid and carbosilane dendrimers with aminopropyl groups. All compounds were characterized by 1H NMR, 13C NMR, IR, GC‐MS, X‐ray photoelectron spectroscopy (XPS) and inductively coupled plasma atomic emission spectroscopy (ICP‐AES). Copyright © 2005 Society of Chemical Industry
Synthesis and characterization of novel dendritic (arborescent, hyperbranched) polyisobutylene–polystyrene block copolymers
Authors: Puskas Judit E. , Kwon Yongmoon , Antony Prince , Bhowmick Anil K.
Published: March 2005

The synthesis of novel arborescent (arb; randomly branched, “tree‐like,” and often called “hyperbranched”) block copolymers comprised of rubbery polyisobutylene (PIB) and glassy polystyrene (PSt) blocks (arb‐PIB‐b‐PSt) is described. The syntheses were accomplished by the use of arb‐PIB macroinitiators (prepared by the use of 4‐(2‐methoxyisopropyl) styrene inimer) in conjunction with titanium tetrachloride (TiCl4). The effect of reaction conditions on blocking of St from arb‐PIB was investigated. Purified block copolymers were characterized by 1H NMR spectroscopy and Size Exclusion Chromatography (SEC). arb‐PIB‐b‐PSt with 11.7–33.8 wt % PSt and Mn = 468,800–652,900 g/mol displayed thermoplastic elastomeric properties with 3.6–8.7 MPa tensile strength and 950–1830% elongation. Samples with 26.8–33.8 wt % PSt were further characterized by Atomic Force Microscopy (AFM), which showed phase‐separated mixed spherical/cylindrical/lamellar PSt phases irregularly distributed within the continuous PIB phase. Dynamic Mechanical Thermal Analysis (DMTA) and solvent swelling of arb‐PIB‐b‐PSt revealed unique characteristics, in comparison with a semicommercial PSt‐b‐PIB‐b‐PSt block copolymer. The number of aromatic branching points of the arb‐PIB macroinitiator, determined by selective destruction of the linking sites, agreed well with that calculated from equilibrium swelling data of arb‐PIB‐b‐PSt. This method for the quantitative determination of branching sites might be generally applicable for arborescent polymers. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1811–1826, 2005
Alkaline and enzymatic degradation of L‐lactide copolymers. II. Crystallized films of poly(L‐lactide‐co‐D‐lactide) and poly(L‐lactide) with similar crystallinities
Authors: Tsuji Hideto , Tezuka Yasufumi , Yamada Kazunobu
Published: March 2005

Films of poly(L‐lactide‐co‐D‐lactide) [P(LLA‐DLA); 95/5] and poly(L‐lactide) [i.e., poly(L‐lactide acid) (PLLA)] were prepared by crystallization from the melt, and a comparative study of the crystallization effects on the alkaline and proteinase K catalyzed hydrolysis of the films was carried out. The hydrolyzed films were investigated with gravimetry, differential scanning calorimetry, polarimetry, and gel permeation chromatography, and the results were compared with those reported for amorphous‐made specimens. The alkaline hydrolyzability of the P(LLA‐DLA) (95/5) and PLLA films was determined solely by the initial crystallinity (Xc) and was not affected by the content of the incorporated D‐lactide (DLA) unit in the polymer chain; this was in marked contrast to the fact that the enzymatic hydrolyzability depended on not only the initial Xc value but also the DLA unit content. The alkaline hydrolysis rate of the P(LLA‐DLA) (95/5) and PLLA films and the enzymatic hydrolysis rate (REH) of the P(LLA‐DLA) (95/5) films decreased linearly as the initial Xc value increased. This meant that the hydrolyzability of the restricted amorphous regions was very similar to that of the free amorphous regions. In contrast, REH of the PLLA films decreased nonlinearly with the initial Xc value, and this nonlinear dependence was caused by the fact that in the PLLA films the restricted amorphous regions were much more hydrolysis‐resistant than the free amorphous regions. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1064‐1075, 2005
Computational identification of proteins for selectivity assays
Authors: Yoon Sukjoon , Smellie Andrew , Hartsough David , Filikov Anton
Published: March 2005

At the stage of optimization of a chemical series the compounds are normally assayed for binding or inhibition on the target protein as well as on several proteins from a selectivity panel. These proteins are normally identified on the basis of sequence homology to the target protein. Experimental selectivity data are also taken into account if available. Cases when a nonhomologous protein has a significant affinity to the compound series are going to be missed if the selectivity panel is identified by homology. Experimental data is usually either unavailable or limited to a small fraction of proteins that should be considered. We have developed a computational method of identification of selectivity panel proteins. It is based on the evaluation of binding site similarity to the target protein using docking scores of target‐selected molecular probes. These probes are obtained by docking a large library of drug‐like compounds to the target protein followed by selecting a diverse subset from the best virtual binders. Docking scores of these probes to other proteins measure binding site similarity to the target. Because the method does not require prior knowledge of either affinities or structures of inhibitors for the target, it can be applied to any protein with known 3D structure. Validation of the method includes rediscovery of nonhomologous proteins that bind common ligands: estradiol, tamoxifen, and riboflavin. Given 3D structures, the method can effectively discriminate proteins with similar binding sites from random proteins independent of sequence homology. Proteins 2005. © 2005 Wiley‐Liss, Inc.
Dropped Gallstones During Laparoscopic Cholesystectomy: The Consequences
Authors: Tumer Ali Riza , Yüksek Yunus Nadi , Yasti Ahmet Cinar , Gözalan Ugur , Kama Nuri Aydin
Published: March 2005

During laparoscopic cholecystectomy, gallbladder perforation has been reported, leading to bile leak and spillage of gallstones into the peritoneum. Because the consequences can be dangerous, conversion to laparotomy as an instant management for gallstone spillage is one of the topics of current discussion in laparoscopic cholesystectomy. In this article, we discussed the option of not converting to laparotomy after intraperitoneal gallstone spillage as an acceptable approach to management or not.

A prospectively maintained database of 1528 consecutive laparoscopic cholecystectomies performed during a 10‐year period at the 4th Surgical Clinic of The Ankara Numune Education and Research Hospital was analyzed. Perforations resulting in gallstone spillage into the abdominal cavity were documented in 58 (3.8%) patients. Among those 58 patients seven (12%) experienced complications from retained stones. To maintain acceptable management of such patients, surgeons should inform each patient preoperatively that stones may be spilled. In the event of spillage, the patient should be informed postoperatively, and followed closely for complications. Follow‐up should not waste time and money with unnecessary examinations, and it should avoid psychological trauma to the patient with a wrong diagnosis of cancer as a stone may mimic cancer radiologically. Thus the surgeon should not hesitate to record the events and inform the patient about the spillage of the stones and possible consequences.
Jaundice at Presentation Heralds Advanced Disease and Poor Prognosis in Patients with Ampullary Carcinoma
Authors: Yokoyama Naoyuki , Shirai Yoshio , Wakai Toshifumi , Nagakura Shigenori , Akazawa Kohei , Hatakeyama Katsuyoshi
Published: March 2005

Jaundice is a common manifestation of ampullary carcinoma. The aim of this study was to evaluate the correlation between jaundice at initial presentation and the degree of tumor spread and to determine the prognostic significance of jaundice in patients with ampullary carcinoma. Fifty‐nine patients who had undergone curative resection for ampullary carcinoma were analyzed retrospectively. Jaundice was defined as a total bilirubin serum concentration of ≥ 3 mg/dl. The median follow‐up time was 106 months. Jaundice was noted at the time of initial presentation in 43 (73%) patients. Jaundice at presentation correlated with lymph node metastasis (p < 0.0001), lymphatic vessel invasion (p < 0.0001), invasion into the pancreas (p = 0.0007), and vascular invasion (p = 0.0487). Pancreatic invasion was absent in patients without jaundice. Superior mesenteric nodal involvement was more frequent in patients with jaundice (15/43) than in those without (0/16) (p = 0.0062). The survival of patients with jaundice (median survival 48 months; cumulative 10‐year survival rate 39%) was worse than for patients without jaundice (median survival time not available; cumulative 10‐year survival rate 86%) (p = 0.0014). In conclusion, jaundice at presentation predicts advanced‐stage ampullary carcinoma and a poor prognosis. Pancreatic invasion and superior mesenteric nodal involvement were not observed in nonjaundiced patients.
Impact of Reconstruction Methods on Outcome of Pancreatoduodenectomy in Pancreatic Cancer Patients
Authors: Doi Ryuichiro , Fujimoto Koji , Kobayashi Hiroyuki , Imamura Masayuki
Published: March 2005

Local recurrence is one of the most frequent forms of pancreatic cancer recurrence, although local recurrence is rare for other periampullary cancers. Because the type of recurrence and outcome differ depending on the type of cancer, these factors should be considered when the type of reconstruction is chosen. Fifty‐four pancreatoduodenectomies were performed in patients with ductal adenocarcinoma of the pancreas from 1994 to 2001. Billroth I reconstruction was performed in 27 consecutive patients before 1999, and thereafter Billroth II reconstruction was performed in another consecutive 27 patients. Postoperative nasogastric intubation and the duration before oral ingestion were longer for Billroth I patients than Billroth II patients. Seven complications occurred in Billroth I patients, whereas there were two complications in Billroth IIpatients. Disease‐free survival and overall survival were not different between the two groups; however, bypass operations were required in nine patients of the Billroth I group and in one patient of the Billroth II group. Percutaneous transhepatic cholangio‐drainage (PTCD) procedures were required in six patients of the Billroth I goup and in two patients of the Billroth II group. The Billroth II reconstruction may have some advantages over the Billroth I reconstruction in terms of postoperative oral ingestion and avoiding bypass surgery and PTCD at the time of recurrence.
Personality, identity styles, and religiosity: An integrative study among late and middle adolescents
Authors: Duriez Bart , Soenens Bart
Published: March 2005

Past research has shown that the way people deal with religion is related to prejudice. Therefore, it is important to study the determinants of individual differences in adolescent religious attitudes. In the present study, it is proposed that both differences in personality and identity formation might determine these religious attitudes. Recently, Duriez, Soenens, and Beyers (2004, Journal of Personality, 72, 877–910) tested an integrative model of the Five Factor Model of personality, Berzonsky's (1990, Advances in Personal Construct Psychology, 1, 155–186) identity styles and the religiosity dimensions of Exclusion vs. Inclusion of Transcendence and Literal vs. Symbolic. In this model, it is assumed that the relationships between adolescent personality and adolescent religious attitudes are mediated by the identity styles. The aim was to replicate this model among late adolescents (Sample 1; ) and to test whether it extends to middle adolescence (Sample 2; ). Whereas most personality factors were weakly and inconsistently related to the religiosity dimensions, Openness to Experience was consistently positively related to Literal vs. Symbolic and negatively to Exclusion vs. Inclusion of Transcendence. Whereas the former relation was mediated by the informational identity style, the latter relation was mediated by the normative identity style in Sample 1 only.
Plant CULLIN‐based E3s: Phytohormones come first
Authors: Thomann Alexis , Dieterle Monika , Genschik Pascal
Published: March 2005

CULLIN (CUL)‐dependent ubiquitin ligases form a class of structurally related multi‐subunit enzymes that control the rapid and selective degradation of important regulatory proteins involved in cell cycle progression and development, among others. Several classes of these E3s are also conserved in plants and genetic analyses, using Arabidopsis thaliana, indicate that they play an important function during plant development and responses to the environment. In this review, we will discuss the molecular composition and function of these enzymes in plants with a major emphasis on phytohormone signal transduction pathways.
Synthetic peptides derived from SARS coronavirus S protein with diagnostic and therapeutic potential
Authors: Lu Wei , Wu Xiao-Dong , Shi Mu De , Yang Rui Fu , He You Yu , Bian Chao , Shi Tie Liu , Yang Sheng , Zhu Xue-Liang , Jiang Wei-Hong , Li Yi Xue , Yan Lin-Chen , Ji Yong Yong , Lin Ying , Lin Guo-Mei , Tian Lin , Wang Jin , Wang Hong Xia , Xie You Hua , Pei Gang , Wu Jia Rui , Sun Bing
Published: March 2005

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS‐CoV) is an important viral structural protein. Based on bioinformatics analysis, 10 antigenic peptides derived from the S protein sequence were selected and synthesized. The antigenicity and immunoreactivity of all the peptides were tested in vivo and in vitro. Four peptides (P6, P8, P9 and P10) which contain B cell epitopes of the S protein were identified, and P8 peptide was confirmed in vivo to have a potential in serological diagnosis. By using a syncytia formation model, we tested the neutralization ability of all 10 peptides and their corresponding antibodies. It is interesting to find that P8 and P9 peptides inhibited syncytia formation, suggesting that the P8 and P9 spanning regions may provide a good target for anti‐SARS‐CoV drug design. Our data suggest that we have identified peptides derived from the S protein of SARS‐CoV, which are useful for SARS treatment and diagnosis.
Locating field science: a geographical family expedition to Glen Roy, Scotland
Authors: LORIMER HAYDEN , SPEDDING NICK
Published: March 2005

This paper reconstructs the historical geographies of a family holiday and field trip in 1952 to Glen Roy, Scotland, site of the famous Parallel Roads. The puzzle of the Parallel Roads' origin has generated a hefty literature over the years, much of it written by eminent scientists, but is here considered through an episode in the scientific history of Glen Roy that did not make the published record. The primary source is the Murray family's expedition logbook: a private and personal document that records the various aspects of life and work in the field. This is supplemented by the family's oral history. Drawing on concepts from science studies and geography, the paper tries to ‘get behind the science’ itself to explore the underlying motives and actions that make it happen. These are intrinsically geographical, because they shape, and are shaped by, the relationships between people, ideas and places. Two themes are central to the account of these other historical geographies of this trip to Glen Roy. The first of these is the coming together of a distinctly local community of knowledge in the Badenoch Field Club in the early 1950s. The second, revealed by the logbook's emphasis on storytelling, travelling and residing, is the way in which the presence of the family in the field changes the ways in which the site of scientific investigation is experienced and understood.
Natural history societies in late Victorian Scotland and the pursuit of local civic science
Authors: FINNEGAN DIARMID A.
Published: March 2005

Nineteenth-century natural history societies sought to address the concerns of a scientific and a local public. Focusing on natural history societies in late Victorian Scotland, this paper concentrates on the relations between associational natural history and local civic culture. By examining the recruitment rhetoric used by leading members and by exploring the public meetings organized by the societies, the paper signals a number of ways in which members worked to make their societies important public bodies in Scottish towns. In addition, by narrating a number of disputes between members over how natural history societies should operate, the paper shows how civic science could occasion social discord rather than harmony. Overall, by investigating the presence of field clubs in different urban settings, and describing members' attempts to portray natural historical pursuits as a significant cultural endeavour, the paper seeks to map an important part of the historical geography of Scottish civic science.
Text, talk and testimony: geographical reflections on scientific habits. An afterword
Authors: LIVINGSTONE DAVID N.
Published: March 2005

A surge of spatial imagery is sweeping across wide stretches of the academy. Spheres of scholarly endeavour hitherto seemingly immune to matters of space and place have been exploiting the geographical lexicon and appending to it ever more imaginative adjectives. Thus literary critics, cultural historians, psychologists, poets and many others have been uncovering geographies that are variously depicted as ‘tender’, ‘neural’, ‘fabulous’, ‘romantic’ and ‘distracted’. Geographers too have added to this adjectival efflorescence with their staging of ‘hybrid’, ‘malevolent’, ‘phobic’ and ‘sensuous’ geographies – to name but a very few. The analytic power of geographical readings has thus been felt across a broad terrain. Thomas Kaufmann, for instance, has recently developed a ‘historical geography of art’ – or what he calls a ‘geohistory of art’ – in which he mobilizes geographical motifs to explore artistic identity, diffusion, circulation and transculturation. Steven Harris, Peter Burke and many others now routinely speak of the ‘geography of knowledge’. And in her recent account of nineteenth-century American expansionism along the western frontier, Amy DeRogatis has found inspiration in the idea of ‘moral geography’ to throw light on the means by which New England ways of life were transferred to the Western Reserve.
The Limits of Selectivity as a Recipe for Welfare Reform: The Case of Greece
Authors: MATSAGANIS MANOS
Published: March 2005

Selectivity emerged as the core of a new social policy paradigm in Greece when a new ‘modernising’ government took office in 1996. Though it was adopted energetically, its real impact eventually proved negligible, except for an initial flutter of activity. The article argues that its failure as a recipe for welfare reform was inevitable. The nature of social protection arrangements in Greece severely constrained the scope for selectivity, while the particular version pursued was poorly designed and badly administered. Moreover, the elevation of selectivity to the status of a ‘Big Idea’ was an indirect cause of serious lateral damage: while fruitlessly puzzling over the place of selectivity in the ‘new social policy’, the government was losing the crucial battle on the reform of an unviable and inequitable pension system. The article concludes that selectivity has little relevance to the priorities for reform in a welfare state still struggling to cope with its Bismarckian, south European contradictions.
Cooling following large volcanic eruptions corrected for the effect of diffuse radiation on tree rings
Authors: Robock Alan
Published: March 2005

The lack of a larger cooling in proxy records of climate change following large volcanic eruptions such as those of Tambora in 1815 and Krakatau in 1883 has long been a puzzle for climatologists. These records, however, may have been biased by enhanced tree growth for several years following each eruption induced by additional diffuse radiation caused by the stratospheric volcanic aerosol clouds from the eruptions. By comparing proxy reconstructions of climate with and without tree ring data, this effect is demonstrated for the five largest eruptions for the period 1750–1980. When proxy records of Northern Hemisphere climate change are corrected for this proposed diffuse effect, there is no impact on climate change for time scales longer than 20 years. However, it now appears that there was a hemispheric cooling of about 0.6°C for a decade following the unknown volcanic eruption of 1809 and Tambora in 1815, and a cooling of 0.3°C for several years following the Krakatau eruption of 1883.
Modeling the dynamics of the inner magnetosphere during strong geomagnetic storms
Authors: Tsyganenko N. A. , Sitnov M. I.
Published: March 2005

This work builds on and extends our previous effort (Tsyganenko et al., 2003) to develop a dynamical model of the storm‐time geomagnetic field in the inner magnetosphere, using space magnetometer data taken during 37 major events in 1996–2000 and concurrent observations of the solar wind and interplanetary magnetic field (IMF). The essence of the approach is to derive from the data the temporal variation of all major current systems contributing to the distant geomagnetic field during the entire storm cycle, using a simple model of their growth and decay. Each principal source of the external magnetic field (magnetopause, cross‐tail current sheet, axisymmetric and partial ring currents, and Birkeland current systems) is driven by a separate variable, calculated as a time integral of a combination of geoeffective parameters NλVβBsγ, where N, V, and Bs are the solar wind density, speed, and the magnitude of the southward component of the IMF, respectively. In this approach we assume that each source has its individual relaxation timescale and residual quiet‐time strength, and its partial contribution to the total field depends on the entire history of the external driving of the magnetosphere during a storm. In addition, the magnitudes of the principal field sources were assumed to saturate during extremely large storms with abnormally strong external driving. All the parameters of the model field sources, including their magnitudes, geometrical characteristics, solar wind/IMF driving functions, decay timescales, and saturation thresholds, were treated as free variables, and their values were derived from the data. As an independent consistency test, we calculated the expected Dst variation on the basis of the model output at Earth's surface and compared it with the actual observed Dst. A good agreement (cumulative correlation coefficient R = 0.92) was found, in spite of the fact that ∼90% of the spacecraft data used in the fitting were taken at synchronous orbit and beyond, while only 3.7% of those data came from distances 2.5 ≤ R ≤ 4 RE. The obtained results demonstrate the possibility to develop a truly dynamical model of the magnetic field, based on magnetospheric and interplanetary data and allowing one to reproduce and forecast the entire process of a geomagnetic storm, as it unfolds in time and space.
Block models of crustal motion in southern California constrained by GPS measurements
Authors: Meade Brendan J. , Hager Bradford H.
Published: March 2005

We estimate slip rates on major active faults in southern California using a block model constrained by Global Positioning System measurements of interseismic deformation. The block model includes the effects of block rotation and elastic strain accumulation consistent with a simple model of the earthquake cycle. Our estimates of the right‐lateral strike‐slip rate on the San Andreas fault vary by at least a factor of 5, from a high of 35.9 ± 0.5 mm/yr in the Carrizo Plain to a low of 5.1 ± 1.5 mm/yr through the San Bernadino segment. Shortening across the Puente Hills Thrust and left‐lateral slip on the Raymond Hill fault are consistent with both thickening and escape tectonics in the Los Angeles Basin. Discrepancies between geodetic and geologic slip rate estimates along the San Andreas and San Jacinto faults, as well as in the Eastern California Shear Zone, may be explained by a temporal change in fault system behavior. We find no substantial evidence for long‐term postseismic relaxation and infer that the viscosity of the lower crust/upper mantle may be relatively high (η > 1019 Pa s).
Evolution of hierarchical self‐similar geometry of experimental fault zones: Implications for seismic nucleation and earthquake size
Authors: Otsuki Kenshiro , Dilov Tzvetan
Published: March 2005

The geometry of fault zones and its evolutionary trend were experimentally investigated for samples of calcareous siltstone nodule through a repetitive procedure of axial loading to grow faults a little, close‐up photographing of faults that appeared on the side surface of the samples, and axial loading again. Irrespective of their size, fault zones are composed of three or four fault segments and compression‐type fault jogs. Smaller segment‐jog structures are nested in larger segments, forming a hierarchical fault zone structure as a whole, and they show self‐similarities. Fault zones grow keeping this self‐similar hierarchical structure. On the basis of this fault zone geometry, we successfully derived the Gutenberg‐Richter's law as well as the previously known relationship of seismic nucleation sizes to seismic moments. These results suggest that fundamentally any seismic rupture nucleates at a smaller jog (asperity) of a lower hierarchical rank and terminates eventually at a larger jog (barrier) of a higher rank, mimicking the hierarchical fault zone geometry.
An evaluation of 14C age relationships between co‐occurring foraminifera, alkenones, and total organic carbon in continental margin sediments
Authors: Mollenhauer Gesine , Kienast Markus , Lamy Frank , Meggers Helge , Schneider Ralph R. , Hayes John M. , Eglinton Timothy I.
Published: March 2005

Radiocarbon age relationships between co‐occurring planktic foraminifera, alkenones, and total organic carbon in sediments from the continental margins of southern Chile, northwest Africa, and the South China Sea were compared with published results from the Namibian margin. Age relationships between the sediment components are site‐specific and relatively constant over time. Similar to the Namibian slope, where alkenones have been reported to be 1000–4500 years older than co‐occurring foraminifera, alkenones were significantly (∼1000 years) older than co‐occurring foraminifera in the Chilean margin sediments. In contrast, alkenones and foraminifera were of similar age (within 2σ error or better) in the NW African and South China Sea sediments. Total organic matter and alkenone ages were similar off Namibia (age difference TOC alkenones: 200–700 years), Chile (100–450 years), and NW Africa (360–770 years), suggesting minor contributions of preaged terrigenous material. In the South China Sea, total organic carbon is significantly (2000–3000 years) older owing to greater inputs of preaged terrigenous material. Age offsets between alkenones and planktic foraminifera are attributed to lateral advection of organic matter. Physical characteristics of the depositional setting, such as seafloor morphology, shelf width, and sediment composition, may control the age of co‐occurring sediment components. In particular, offsets between alkenones and foraminifera appear to be greatest in deposition centers in morphologic depressions. Aging of organic matter is promoted by transport. Age offsets are correlated with organic richness, suggesting that formation of organic aggregates is a key process.
Mass renormalization in nonrelativistic quantum electrodynamics
Authors: Hiroshima Fumio , Spohn Herbert
Published: March 2005

In nonrelativistic quantum electrodynamics the charge of an electron equals its bare value, whereas the self-energy and the mass must be renormalized. In our contribution we study perturbative mass renormalization, including second order in the fine structure constant α, in the case of a single, spinless electron. As is well known, if m denotes the bare mass and meff the mass computed from the theory, to order α one has meff∕m=1+(8α∕3π)log(1+12(Λ∕m))+O(α2) which suggests that meff∕m=(Λ∕m)8α∕3π for small α. If correct, in order α2 the leading term should be 12((8α∕3π)log(Λ∕m))2. To check this point we expand meff∕m to order α2. The result is Λ∕m as leading term, suggesting a more complicated dependence of meff on m.
Reaction path determination for quantum mechanical/molecular mechanical modeling of enzyme reactions by combining first order and second order “chain-of-replicas” methods
Authors: Cisneros G. Andrés , Liu Haiyan , Lu Zhenyu , Yang Weitao
Published: March 2005

A two-step procedure for the determination of reaction paths in enzyme systems is presented. This procedure combines two chain-of-states methods: a quantum mechanical/molecular mechanical (QM/MM) implementation of the nudged elastic band (NEB) method and a second order parallel path optimizer method both recently developed in our laboratory. In the first step, a reaction path determination is performed with the NEB method, along with a restrained minimization procedure for the MM environment to obtain a first approximation to the reaction path. In the second step, the calculated path is refined with the parallel path optimizer method. By combining these two methods the reaction paths are determined accurately, and in addition, the number of path optimization iterations are significantly reduced. This procedure is tested by calculating both steps of the isomerization of 2-oxo-4-hexenedioate by 4-oxalocrotonate tautomerase, which have been previously determined by our group. The calculated paths agree with the previously reported results and we obtain a reduction of 45%–55% in the number of path optimization cycles.
Experimental and theoretical investigation of the reaction NH(XΣ−3)+H(S2)→N(S4)+H2(XΣg+1)
Authors: Adam L. , Hack W. , Zhu H. , Qu Z.-W. , Schinke R.
Published: March 2005

The rate coefficient of the reaction NH(XΣ−3)+H(S2)→k1aN(S4)+H2(XΣg+1) is determined in a quasistatic laser-flash photolysis, laser-induced fluorescence system at low pressures (2mbar⩽p⩽10mbar). The NH(X) radicals are produced via the quenching of NH(aΔ1) (obtained by photolyzing HN3) with Xe whereas the H atoms are generated in a H2∕He microwave discharge. The NH(X) concentration profile is measured under pseudo-first-order condition, i.e., in the presence of a large excess of H atoms. The room temperature rate coefficient is determined to be k1a=(1.9±0.5)×1012cm3mol−1s−1. It is found to be independent of the pressure in the range considered in the present experiment. A global potential energy surface for the A″4 state is calculated with the internally contracted multireference configuration interaction method and the augmented correlation consistent polarized valence quadruple zeta atomic basis. The title reaction is investigated by classical trajectory calculations on this surface. The theoretical room temperature rate coefficient is k1a=0.92×1012cm3mol−1s−1. Using the thermodynamical data for the atoms and molecules involved, the rate coefficient for the reverse reaction, k−1a, is also calculated. At high temperatures it agrees well with the measured k−1a.
Microstructure of nanocrystalline diamond powders studied by powder diffractometry
Authors: Palosz B. , Grzanka E. , Pantea C. , Zerda T. W. , Wang Y. , Gubicza J. , Ungár T.
Published: March 2005

High resolution x-ray diffraction peaks of diamond nanosize powders of nominal sizes ranging from 5 to 250nm were analyzed and provided information on grain structure, average size of crystallites, and concentration of dislocations. Selected samples were heat treated at 1670K at pressures 2.0 and 5.5GPa or had surface modified by outgassing, heat treatment at vacuum conditions, and by controlled adsorption of gases. The apparent lattice parameter method was applied to characterize the structure of a shell-core model of nanosize particles. The multiple whole profile fitting provided information on crystallite sizes and density of dislocations. Population of dislocations increased with applied pressure, while strain and interplanar distances in the surface layers decreased. Adsorption of foreign gases on the grain surface modified the structure of the surface layers but did not affect dislocations near the center of the grains.
Micromachined force sensors for the study of cell mechanics
Authors: Yang Shengyuan , Saif Taher
Published: March 2005

A technique using micromachined mechanical force sensors to measure the force response of living cells is introduced. The force sensors consist of a probe and flexible beams. The probe is used to indent and stretch the cells, and the flexible beams are used to measure the cell force response. The stiffness of the sensors is designed at several nanonewtons per micrometer, but can be varied over a wide range. The sensors are fabricated by the SCREAM process. The deformation of the cells and the deflection of flexible beams are measured by an optical microscope coupled with a charge-coupled device camera. Experimental demonstrations show the feasibility, simplicity, and versatility of this technique. It addresses several disadvantages of existing related techniques, and is complementary to many of them. We expect that this new technique will attract significant attention and be employed much more in the study of cell mechanics.
Using multispectral imaging to measure temperature profiles and emissivity of large thermionic dispenser cathodes
Authors: Simmons David F. , Fortgang Clifford M. , Holtkamp David B.
Published: March 2005

The authors measured temperature, temperature uniformity, and emissivity of two large thermionic tungsten cathodes. This was necessary because their operating life is strongly affected by nonuniformities in temperature. The cathodes were self-heated 6.5 and 8-in. disks operating in a vacuum at about 1l00 °C. We measured the temperature of the cathodes by a combination of multispectral imaging using a conventional CCD camera and spot pyrometry using three spot pyrometers. We took images at the blue end of the spectrum (0.4 μm) to determine temperature accurate to 3% K. Spot pyrometers at the red end of the spectrum (to 1.8 μm) yielded emissivity with an uncertainty of 15%. We emphasized using data in the blue to determine the temperature and data in the red to determine emissivity. Our analysis displays data so that assumptions in determining temperature and emissivity are transparent. Because we obtained a linear relationship between camera counts and integrated exitance of a blackbody, we concluded that the camera was calibrated correctly.
The development of helical vortex filaments in a tube
Authors: Sarasua L. G. , Sicardi Schifino A. C. , González R.
Published: March 2005

We study the formation of helical vortex filaments in a tube. The helical flow is assumed to be potential except in a very slender core. The boundary conditions are satisfied by introducing a helical image vortex. By assuming an axisymmetric flow upstream and imposing conservation laws, we obtain a set of conditions that must be satisfied by the helical flow downstream. We obtain that, when a generalized swirl parameter Ω reaches a critical value Ωc a bifurcation occurs and for Ω>Ωc there are two solutions for the helical filamentary vortex. Such a bifurcation can be produced by increasing the swirl level of the inlet flow or the radius of the outlet tube, in agreement with experiments. We have discussed the influence of the core size and the Reynolds number on Ωc and with these results we have explained some experimental observations.
Displacement amplitude scaling of a two-dimensional synthetic jet
Authors: Fugal Spencer R. , Smith Barton L. , Spall Robert E.
Published: March 2005

A two-dimensional synthetic jet is studied numerically by solving the incompressible, unsteady, Reynolds-averaged, Navier–Stokes equations and using a k-ϵ turbulence model. Rather than a resonant cavity, the synthetic jet is supplied by a fully developed channel flow. Results for two exit geometries, a sharp exit and a rounded exit, and several dimensionless stroke lengths are compared. This study focuses on the effect of the displacement amplitude (stroke length) on the power required to form the jet, the net momentum flux downstream of the exit, the formation threshold, and the spatial development of the synthetic jet. It is shown that the channel flow development length, the self-similar region, and the region from which the jet draws fluid all scale on the stroke length. It is also demonstrated that the power required to form the jet increases with stroke length as does the resultant momentum flux. Finally, the power required to form a synthetic jet is significantly smaller for a rounded exit compared to a sharp-edged exit.
Path integral ground state with a fourth-order propagator: Application to condensed helium
Authors: Cuervo Javier E. , Roy Pierre-Nicholas , Boninsegni Massimo
Published: March 2005

Ground state properties of condensed helium are calculated using the path integral ground state (PIGS) method. A fourth-order approximation is used as short (imaginary) time propagator. We compare our results with those obtained with other quantum Monte Carlo (QMC) techniques and different propagators. For this particular application, we find that the fourth-order propagator performs comparably to the pair product approximation, and is far superior to the primitive approximation. Results obtained for the equation of state of condensed helium show that PIGS compares favorably to other QMC methods traditionally utilized for this type of calculation.
The equilibrium properties and folding kinetics of an all-atom Go¯ model of the Trp-cage
Authors: Linhananta Apichart , Boer Jesse , MacKay Ian
Published: March 2005

The ultrafast-folding 20-residue Trp-cage protein is quickly becoming a new benchmark for molecular dynamics studies. Already several all-atom simulations have probed its equilibrium and kinetic properties. In this work an all-atom Go¯ model is used to accurately represent the side-chain packing and native atomic contacts of the Trp-cage. The model reproduces the hallmark thermodynamics cooperativity of small proteins. Folding simulations observe that in the fast-folding dominant pathway, partial α-helical structure forms before hydrophobic core collapse. In the slow-folding secondary pathway, partial core collapse occurs before helical structure. The slow-folding rate of the secondary pathway is attributed to the loss of side-chain rotational freedom, due to the early core collapse, which impedes the helix formation. A major finding is the observation of a low-temperature kinetic intermediate stabilized by a salt bridge between residues Asp-9 and Arg-16. Similar observations [R. Zhou, Proc. Natl. Acad. Sci. U.S.A. 100, 13280 (2003)] were reported in a recent study using an all-atom model of the Trp-cage in explicit water, in which the salt-bridge stabilized intermediate was hypothesized to be the origin of the ultrafast-folding mechanism. A theoretical mutation that eliminates the Asp-9-Arg-16 salt bridge, but leaves the residues intact, is performed. Folding simulations of the mutant Trp-cage observe a two-state free-energy landscape with no kinetic intermediate and a significant decrease in the folding rate, in support of the hypothesis.
Comparison of the electronic properties of sublimation- and vapor-Bridgman-grown crystals of tetracene
Authors: Niemax J. , Tripathi A. K. , Pflaum J.
Published: March 2005

The hole mobilities in a vapor-Bridgman-grown crystal and in sublimation-grown crystals of tetracene were measured along the c*-direction in a temperature range from 300to450K by the time-of-flight method. The mobility was found to increase as a function of temperature in the vapor-Bridgman-grown crystal, indicating that the transport was thermally activated. After reaching its maximum of about 1cm2∕Vs at 320K, the mobility in the sublimation-grown crystals decreased with temperature in accordance with band transport models. Gas chromatography measurements indicated that the difference in the electronic transport properties could be related to a higher concentration of chemical impurities in the vapor-Bridgman crystal.
Spin-polarized quasiparticles injection in La0.7Sr0.3MnO3∕SrTiO3∕Nb heterostructure devices
Authors: Fratila L. , Maurin I. , Dubourdieu C. , Villégier J. C.
Published: March 2005

We report the effect of spin-polarized quasiparticle injection from a ferromagnetic manganite into a conventional Nb superconductor in a La0.7Sr0.3MnO3∕SrTiO3∕Nb heterostructure. A 8-terminal stacked trilayer geometry was used, where the injected current Iinj enters a superconducting microbridge and leaves it symmetrically by tunneling through a SrTiO3 barrier. A high dynamic gain G=−dIc∕dIinj was observed from 1.7 up to 8.5K, where Ic is the microbridge critical current. For a dc injection current, G was measured to be 290 at 1.7K. A SrTiO3 barrier of thickness in the range 3.5–8.5nm was found to provide a suitable spin injection length of the order of the bridge length and a low Joule heating level. In this confined stacked device geometry it was found that Joule dissipation in the manganite and barrier does not contribute significantly to the suppression of Ic, in contrast with previous studies.
Unpolarized narrow-band filtering with resonant gratings
Authors: Fehrembach Anne-Laure , Sentenac Anne
Published: March 2005

Periodically corrugated planar waveguides present sharp peaks in their reflectivity spectrum due to the excitation, by the incident beam, of an eigenmode of the structure. This property can be used to design free-space narrow-band filters. However, the extreme sensitivity of the resonances with respect to the angle and polarization under oblique incidence, has prevented, up to now, the development of efficient filters with this approach. We succeed in getting round these limitations by exiting four eigenmodes at the same time, and by modifying deeply the eigenmodes properties with an appropriate periodic corrugation.
Propagation losses of silicon nitride waveguides in the near-infrared range
Authors: Melchiorri M. , Daldosso N. , Sbrana F. , Pavesi L. , Pucker G. , Kompocholis C. , Bellutti P. , Lui A.
Published: March 2005

Si 3 N 4 ∕ SiO 2 waveguides have been fabricated by low pressure chemical vapor deposition within a complementary metal–oxide–semiconductor fabrication pilot line. Propagation losses for different waveguide geometries (channel and rib loaded) have been measured in the near infrared as a function of polarization, waveguide width, and light wavelength. A maximum thickness of single Si3N4 of 250 nm is allowed by the large stress between Si3N4 and SiO2. This small thickness turns into significant propagation losses at 1544 nm of about 4.5dB∕cm because of the poor optical mode confinement factor. Strain release and control is possible by using multilayer waveguides by alternating Si3N4 and SiO2 layers. In this way, propagation losses of about 1.5dB∕cm have been demonstrated thanks to an improved optical mode confinement factor and the good quality of the interfaces in the waveguide.
The polyglutamine neurodegenerative protein ataxin 3 regulates aggresome formation
Authors: Burnett Barrington G. , Pittman Randall N.
Published: March 2005

The polyglutamine-containing neurodegenerative protein ataxin 3 (AT3) has deubiquitylating activity and binds ubiquitin chains with a preference for chains of four or more ubiquitins. Here we characterize the deubiquitylating activity of AT3
in vitro
and show it trims/edits K48-linked ubiquitin chains. AT3 also edits polyubiquitylated
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I-lysozyme and decreases its degradation by proteasomes. Cellular studies show that endogenous AT3 colocalizes with aggresomes and preaggresome particles of the misfolded cystic fibrosis transmembrane regulator (CFTR) mutant CFTRΔF508 and associates with histone deacetylase 6 and dynein, proteins required for aggresome formation and transport of misfolded protein. Small interfering RNA knockdown of AT3 greatly reduces aggresomes formed by CFTRΔF508, demonstrating a critical role of AT3 in this process. Wild-type AT3 restores aggresome formation; however, AT3 with mutations in the active site or ubiquitin interacting motifs cannot restore aggresome formation in AT3 knockdown cells. These same mutations decrease the association of AT3 and dynein. These data indicate that the deubiquitylating activity of AT3 and its ubiquitin interacting motifs as well play essential roles in CFTRΔF508 aggresome formation.