bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential resistance to cell entry by porcine endogenous retrovirus subgroup A in rodent species
Authors: Mattiuzzo Giada , Matouskova Magda , Takeuchi Yasuhiro
Published: February 2008

Background

The risk of zoonotic infection by porcine endogenous retroviruses (PERV) has been highlighted in the context of pig-to-human xenotransplantation. The use of receptors for cell entry often determines the host range of retroviruses. A human-tropic PERV subgroup, PERV-A, can enter human cells through either of two homologous multitransmembrane proteins, huPAR-1 and huPAR-2. Here, we characterised human PARs and their homologues in the PERV-A resistant rodent species, mouse and rat (muPAR and ratPAR, respectively).

Results

Upon exogenous expression in PERV-A resistant cells, human and rat PARs, but not muPAR, conferred PERV-A sensitivity. Exogenously expressed ratPAR binds PERV-A Env and allows PERV-A infection with equivalent efficiency to that of huPAR-1. Endogenous ratPAR expression in rat cell lines appeared to be too low for PERV-A infection. In contrast, the presence of Pro at position 109 in muPAR was identified to be the determinant for PERV-A resistance. Pro109. was shown to be located in the second extracellular loop (ECL2) and affected PERV-A Env binding to PAR molecules.

Conclusion

The basis of resistance to PERV-A infection in two rodent species is different. Identification of a single a.a. mutation in muPAR, which is responsible for mouse cell resistance to PERV-A highlighted the importance of ECL-2 for the viral receptor function.
Effect of prolonged intravenous glucose and essential amino acid infusion on nitrogen balance, muscle protein degradation and ubiquitin-conjugating enzyme gene expression in calves
Authors: Sadiq Fouzia , Crompton Leslie A , Scaife Jes R , Lomax Michael A
Published: February 2008

Background

Intravenous infusions of glucose and amino acids increase both nitrogen balance and muscle accretion. We hypothesised that co-infusion of glucose (to stimulate insulin) and essential amino acids (EAA) would act additively to improve nitrogen balance by decreasing muscle protein degradation in association with alterations in muscle expression of components of the ubiquitin-proteasome proteolytic pathway.

Methods

We examined the effect of a 5 day intravenous infusions of saline, glucose, EAA and glucose + EAA, on urinary nitrogen excretion and muscle protein degradation. We carried out the study in 6 restrained calves since ruminants offer the advantage that muscle protein degradation can be assessed by excretion of 3 methyl-histidine and multiple muscle biopsies can be taken from the same animal. On the final day of infusion blood samples were taken for hormone and metabolite measurement and muscle biopsies for expression of ubiquitin, the 14-kDa E2 ubiquitin conjugating enzyme, and proteasome sub-units C2 and C8.

Results

On day 5 of glucose infusion, plasma glucose, insulin and IGF-1 concentrations were increased while urea nitrogen excretion and myofibrillar protein degradation was decreased. Co-infusion of glucose + EAA prevented the loss of urinary nitrogen observed with EAA infusions alone and enhanced the increase in plasma IGF-1 concentration but there was no synergistic effect of glucose + EAA on the decrease in myofibrillar protein degradation. Muscle mRNA expression of the ubiquitin conjugating enzyme, 14-kDa E2 and proteasome sub-unit C2 were significantly decreased, after glucose but not amino acid infusions, and there was no further response to the combined infusions of glucose + EAA.

Conclusion

Prolonged glucose infusion decreases myofibrillar protein degradation, prevents the excretion of infused EAA, and acts additively with EAA to increase plasma IGF-1 and improve net nitrogen balance. There was no evidence of synergistic effects between glucose + EAA infusion on muscle protein degradation or expression of components of the ubiquitin-proteasome proteolytic pathway.
Assessment of three-dimensional set-up errors in conventional head and neck radiotherapy using electronic portal imaging device
Authors: Gupta Tejpal , Chopra Supriya , Kadam Avinash , Agarwal Jai Prakash , Devi P Reena , Ghosh-Laskar Sarbani , Dinshaw Ketayun Ardeshir
Published: February 2008

Background

Set-up errors are an inherent part of radiation treatment process. Coverage of target volume is a direct function of set-up margins, which should be optimized to prevent inadvertent irradiation of adjacent normal tissues. The aim of this study was to evaluate three-dimensional (3D) set-up errors and propose optimum margins for target volume coverage in head and neck radiotherapy.

Methods

The dataset consisted of 93 pairs of orthogonal simulator and corresponding portal images on which 558 point positions were measured to calculate translational displacement in 25 patients undergoing conventional head and neck radiotherapy with antero-lateral wedge pair technique. Mean displacements, population systematic (Σ) and random (σ) errors and 3D vector of displacement was calculated. Set-up margins were calculated using published margin recipes.

Results

The mean displacement in antero-posterior (AP), medio-lateral (ML) and supero-inferior (SI) direction was -0.25 mm (-6.50 to +7.70 mm), -0.48 mm (-5.50 to +7.80 mm) and +0.45 mm (-7.30 to +7.40 mm) respectively. Ninety three percent of the displacements were within 5 mm in all three cardinal directions. Population systematic (Σ) and random errors (σ) were 0.96, 0.98 and 1.20 mm and 1.94, 1.97 and 2.48 mm in AP, ML and SI direction respectively. The mean 3D vector of displacement was 3.84 cm. Using van Herk's formula, the clinical target volume to planning target volume margins were 3.76, 3.83 and 4.74 mm in AP, ML and SI direction respectively.

Conclusion

The present study report compares well with published set-up error data relevant to head and neck radiotherapy practice. The set-up margins were <5 mm in all directions. Caution is warranted against adopting generic margin recipes as different margin generating recipes lead to a different probability of target volume coverage.
Insulin-related decrease in cerebral glucose despite normoglycemia in aneurysmal subarachnoid hemorrhage
Authors: Schlenk Florian , Graetz Daniela , Nagel Alexandra , Schmidt Maren , Sarrafzadeh Asita S
Published: February 2008

Introduction

Hyperglycaemia following aneurysmal subarachnoid hemorrhage (SAH) is associated with complications and impaired neurological recovery. The aim of this study was to determine the effect of insulin treatment for glucose control on cerebral metabolism in SAH patients.

Methods

This prospective, nonrandomized study was conducted in 31 SAH patients in an intensive care unit (age 52 ± 10 years, World Federation of Neurological Surgeons grade 2.9 ± 1.6). A microdialysis catheter was inserted into the vascular territory of the aneurysm after clipping. Blood glucose levels above 140 mg/dl were treated with intravenous insulin and the microdialysates were analyzed hourly for the first 12 hours of infusion.

Results

No hypoglycaemia occurred. Twenty-four patients were treated with insulin for glucose control. Higher age and World Federation of Neurological Surgeons score were risk factors for need for insulin treatment (P < 0.05). Although blood glucose remained stable after initiation of insulin infusion, insulin induced a significant decrease in cerebral glucose at 3 hours after onset of the infusion until the end of the observation period (P < 0.05), reflecting high glucose utilization. The lactate:pyruvate ratio and glutamate did not increase, excluding ischaemia as possible cause of the decrease in glucose. Glycerol tended toward higher values at the end of the observation period (9 to 12 hours), reflecting either tissue damage after SAH or the beginning of cellular distress after insulin infusion.

Conclusion

Higher SAH grade was among the risk factors for need for insulin. Intensive glycaemic control using insulin induced a decrease of cerebral glucose and a slight increase in glycerol, though blood glucose remained normal. Future studies might detect relevant metabolic derangements when insulin treatment starts at low cerebral glucose levels, and may allow us to design a strategy for avoidance of insulin-induced metabolic crisis in SAH patients.
Prospective Oral Mucositis Audit: Oral Mucositis in Patients Receiving High-Dose Melphalan or BEAM Conditioning Chemotherapy—European Blood and Marrow Transplantation Mucositis Advisory Group
Authors: Blijlevens Nicole , Schwenkglenks Matthias , Bacon Pamela , D'Addio Alessandra , Einsele Hermann , Maertens Johan , Niederwieser Dietger , Rabitsch Werner , Roosaar Ann , Ruutu Tapani , Schouten Harry , Stone Rebecca , Vokurka Samuel , Quinn Barry , McCann Shaun
Published: February 2008

Purpose

The Prospective Oral Mucositis Audit assessed the incidence, duration, and determinants of severe oral mucositis (OM; WHO oral toxicity scale grades 3 to 4) in patients with multiple myeloma (MM) or non-Hodgkin's lymphoma (NHL) receiving high-dose conditioning chemotherapy before autologous stem-cell transplantation.

Patients and Methods

Patients with MM (n = 109; mean age, 57 ± 8 years) or NHL (n = 88; mean age, 50 ± 13 years) were treated with high-dose melphalan (200 mg/m2) or carmustine 300 mg/m2, etoposide 800 mg/m2, cytarabine 800 to 1,600 mg/m2, and melphalan 140 mg/m2 chemotherapy, respectively, in 25 European centers. OM assessments were made daily until 30 days after transplantation or hospital discharge. High quality of OM assessment was ensured by an intensive training program.

Results

Severe OM occurred in 46% (95% CI, 36% to 56%) of patients with MM and 42% (95% CI, 32% to 53%) of patients with NHL, with a mean duration of 5.3 days (95% CI, 4.4 to 6.1 days) and 5.5 days (95% CI, 4.5 to 6.7 days), respectively. Time from start of conditioning to peak OM score was 12.1 ± 2.6 and 14.6 ± 2.4 days. Severe OM risk and/or duration was significantly associated with higher chemotherapy dose per kilogram of body weight and poor performance status, but in contrast with some previous reports, this was not related to age.

Conclusion

Severe OM is more common in the transplantation setting than previously reported, justifying effective preventative and therapeutic measures.
Complexity and Foregrounding: In the Eye of the Beholder?
Authors: Zyngier Sonia , van Peer Willie , Hakemulder Jèmeljan
Published: February 2008

This article approaches from an empirical perspective the interrelation between foregrounding and complexity in the evaluation of literary texts. For this purpose, a reading experiment is reported. Participants from three cultures (Brazil, Egypt, and the Netherlands) read three texts of different degrees of complexity and evaluated them on a number of variables. Subsequently, they re-read and evaluated the texts once more. The hypothesis was that complex texts would be rated higher on a second than on a first reading; the opposite was predicted for the text with the lowest complexity. Results confirmed this hypothesis for only one group of participants, which raises questions about the nature of a “reading culture.”
Photo-Induced State Conversion Mechanism of an Optically Durable Molecular Memory with Controlled Hydrogen Bonding: A Spin–Orbit CI Study of [{Co(2,2′-biimidazole)(C6H4O2)(NH3)2}2]
Authors: Mori Hirotoshi , Miyoshi Eisaku
Published: February 2008

The possibility for photon-mode memory writing of [{Co(Hbim)(C6H4O2)(NH3)2}2] (Hbim = 2,2′-biimidazole) is examined from results obtained by spin–orbit complete active space configuration interaction (SO-CASCI) calculations. The spin-crossover phenomenon in the proton–electron-coupled complex monomer [Co(Hbim)(C6H4O2)(NH3)2] is a key process in memory writing to the complex dimer. We found a possibility of an efficient spin-crossover in the monomer. UV (ca. 300 nm) irradiation of the monomer 1A′ state leads to a spin-crossover into the high-spin 5A′ state. The back photoreaction from the 5A′ to 1A′ state is also possible with vis (ca. 600–700 nm) excitation. In these spin-crossover and back spin-crossover reactions, the intermediate triplet states, 13A″ and 23A″, are found to participate.
Dimensionality of Aromaticity
Authors: Aihara Jun-ichi
Published: February 2008

Aromaticity has been viewed as multidimensional, because different scales of aromaticity sometimes make different predictions as to the aromaticity of a polycyclic π-system. Our graph theory of aromaticity and ring-current diamagnetism enables us to interpret magnetic scales of aromaticity in terms of aromatic stabilization energy (ASE). We have now no reason to regard any magnetic scale of aromaticity as a scale orthogonal to the energetic ones. Aromaticity is one-dimensional in this sense and should in principle be described in terms of ASE. Other scales of aromaticity, such as geometric ones, must likewise reflect ASE to varying extents, although it is not easy to interpret them analytically in energetic terms.
A Damped Oscillator Model for Infrared Spectra of Formamide in the Liquid State
Authors: Kanesaka Isao , Mitsuhashi Eiji
Published: February 2008

Infrared spectra of formamide are wholly simulated for the in-plane modes on the basis of a damped oscillator model, where force constants and intensity parameters and damping constants defined in every Cartesian displacement coordinate are simultaneously adjusted. Band constants evaluated from the damped oscillator model are compared with those observed. The present analysis reveals the relation in band widths among all vibrational modes, in other words, the origin of band widths. Large values of the damping constant on H in the NH2 group result from inter-molecular interactions, i.e., hydrogen bonds. Unexpected results of the damping constants on O, C, and N are discussed with van der Waals forces and intra-molecular interactions.
Synthesis, Characterization, and Conducting Properties of Heterobimetallic Salts of Cyanoiminomethanedithiolate Ligand
Authors: Singh Nanhai , Singh Bandana
Published: February 2008

Heterobimetallic ion-pair complexes of the type [M(bpy)3][M′(cdc)2] (M = Fe2+, Co2+, and Ni2+; M′ = Ni2+ and Cu2+; bpy = 2,2′-bipyridine, cdc2− = cyanoiminomethanedithiolate (C2N2S22−)) have been synthesized by reacting a solution of K2[M′(cdc)2] with [M(bpy)3]X2 (X = Cl− and SO42−) in equimolar ratio. These complexes have been characterized by elemental analysis, solution conductance, and magnetic susceptibility measurements, IR, 1H and 13C NMR, ESR, and UV–visible spectroscopies and pressed pellet conductivity technique. Three of these salts show behavior of semiconductors in the 295–443 K temperature range while the remaining are insulators. The lowering of the ν(C≡N) frequency in I2-doped products of these complexes as compared to the parent complexes clearly reveals interaction of the C≡N group of the ligand cdc2− resulting in decrease in ν(C≡N) bond order and in turn partial reduction of I2. The I2-doped products of the majority of the complexes show enhanced room-temperature conductivity and exhibit semiconducting behavior.
Preparation of Titania Nanotube Thin Films by Langmuir–Blodgett Technique
Authors: Takahashi Masashi , Okada Yuichi , Kobayashi Koichi
Published: February 2008

Preparation of thin titania nanotube films has been attempted using Langmuir–Blodgett (LB) technique. The resulting LB monolayer exhibited closely packed arrangement of the nanotube bundles in a monoparticulate layer on the solid substrate. Also, domain structure due to strong lateral interaction among the bundles lying side-by-side was observed even for the LB films deposited at a low surface pressure. Moreover, multilayer deposition of the monoparticulate films provided precise control of the film thickness.
Phosphine-dependent Stereoselective Nucleophilic Reaction to Bicyclic Bis-μ-dichloro-η3-allylpalladium Complexes
Authors: Ogawa Ryohei , Nakajima Takayuki , Shimizu Isao
Published: February 2008

The effects on ligands in nucleophilic reaction of η3-allylpalladium chloride dimers were studied. Reaction of steroid 1 with Na2PdCl4 in concentrated HCl under CO gave the cis,trans-bis-μ-dichloro-η3-allylpalladium complex 2 after recrystallization. Reaction of 2 with malonate anion in the presence of PPh3 afforded trans-3 in 65% yield. When Dppe was used, cis-3 was obtained as the major product. In nucleophilic reactions of bicyclic η3-allylpalladium chloride complex 4a or 4b with PPh3, cis-5 was the major product. However, the reaction with Dppe gave trans-5 predominantly. The stereochemistry in the nucleophilic reaction of η3-allylpalladium chloride dimer is dependent on the added phosphines.
Stereoselective Insertion of Rhodium Carbenoid to Water under Control with Intramolecular Participation of Hydroxy Group
Authors: Sugimura Takashi , Nagai Takao
Published: February 2008

A chiral diazo ester having a hydroxy group in the proper geometry produces an adduct with water up to 92% de upon treatment with a rhodium catalyst. This high stereoselectivity is attributable to the intramolecular hydrogen bond between the internal hydroxy group and the rhodium carbenoid.
Solution-processible Fluorinated Carbazole Derivative for Phosphorescent Organic Light-emitting Diodes
Authors: Ge Ziyi , Hayakawa Teruaki , Ando Shinji , Ueda Mitsuru , Akiike Toshiyuki , Miyamoto Hidetoshi , Kajita Toru , Kakimoto Masa-aki
Published: February 2008

A fluorinated carbazole, 9,9′-[2,2′-bis(trifluoromethyl)biphenyl-4,4′-diyl]bis(9H-carbazole) (6FCBP) was prepared, which exhibited better solubility compared to the well-known hole-transporting material 4,4′-bis(carbazol-9-yl)biphenyl (CBP). 6FCBP was employed to fabricate OLEDs by spin coating or vacuum deposition with excellent performance.
Activation and Dehydrogenative Silylation of the C–H Bonds of Phosphine-coordinated Ruthenium in Lu/Ru Heteromultimetallic Hydride Complexes
Authors: Shima Takanori , Hou Zhaomin
Published: February 2008

The reaction of half-sandwich lutetium dialkyl complex Cp∗Lu(CH2SiMe3)2(THF) (Cp∗= C5Me5) with ruthenium–trihydrido–phosphine complexes Cp∗Ru(PR3)H3 (R3 = Ph3, Ph2Me, PhMe2, and Me3) at 50 °C afforded the corresponding Lu/Ru heterobimetallic dihydride complexes, which was accompanied by selective C–H bond activation of the phosphine ligand. The reaction of such a resulting phosphinomethyl-bridged Lu/Ru complex with PhSiH3 led to selective dehydrogenative silylation at the “CH2” unit.
Sluggish Institutions in a Dynamic World: Can Unions and Industrial Competition Coexist?
Authors: Hirsch Barry T
Published: February 2008

During the 1930s and 1940s, collective bargaining emerged as the workplace governance norm in much of the U.S. industrial sector. Following its peak in the 1950s, union density in the U.S. private sector fell steadily, to only 7.4 percent in 2006. Governance shifted from a formalized union norm to one of constrained managerial discretion. In competitive and dynamic economic environments, a union tax on company earnings and slow response to economic shocks combine to produce poor performance by union companies. Two industries—automotives and airlines—are used to illustrate these points. If worker-based institutions are to flourish, they must add value and permit companies to perform at levels similar to those obtained under evolving nonunion governance norms.
Guaranteed Trouble: The Economic Effects of the Pension Benefit Guaranty Corporation
Authors: Brown Jeffrey R
Published: February 2008

How did the Pension Benefit Guaranty Corporation, a government corporation created to insure the pensions of workers and retirees in bankrupt firms, end up facing financial distress of its own? How did an organization designed to strengthen retirement security come to be seen as contributing to retirement insecurity? The superficial answer is that the PBGC's current funding problem arises from the decline in stock market prices in 2000, which reduced pension assets, and the fall in interest rates at about the same time, which boosted the present value of pension liabilities. But more fundamentally, much of the blame for the poor financial state of the PBGC, as well as the defined benefit system more generally, lies in some major design flaws of the PBGC pension insurance program. Specifically, the PBGC has: 1) failed to properly price insurance and thus encouraged excessive risk-taking by plan sponsors; 2) failed to promote adequate funding of pension obligations; and 3) failed to promote sufficient information disclosure to market participants. Together, these three flaws produced a system in which many firms fail to adequately fund their pension obligations, knowing that in financial distress, they can dump their pension liabilities onto the PBGC. Though the Pension Protection Act of 2006 made some progress in improving the PBGC program, it failed to correct these three major problems fully. Absent further reform, substantial problems will continue to plague the private defined benefit pension system in decades to come. To prevent this deterioration, this paper concludes that Congress should transfer much of the responsibility for defined benefit pension insurance to compulsory private markets.
Dispelling Some Misconceptions about Agricultural Trade Liberalization
Authors: Tokarick Stephen
Published: February 2008

There has been a great deal of public discussion over the impact that agricultural trade liberalization would likely have, especially on low-income countries. Unfortunately, the public discussion has been characterized by a number of misconceptions. This paper provides a clarifying discussion of the issues involved. Among the key points addressed are 1) agricultural “subsidies” are not nearly as large as has been portrayed; 2) tariffs are actually far more distortionary than subsidies and some low-income countries actually benefit from rich country subsides; and 3) widespread tariff reductions will not inflict large damage on developing countries as a result of preference erosion. The case for removing agricultural trade barriers remains compelling, even without the exaggerations and misconceptions.
Markets: Ready-Mixed Concrete
Authors: Syverson Chad
Published: February 2008

Concrete's natural color is gray. Its favored uses are utilitarian. Its very ubiquity causes it to blend into the background. But ready-mix concrete does have one remarkable characteristic: other than manufactured ice, perhaps no other manufacturing industry faces greater transport barriers. The transportation problem arises because ready-mix concrete both has a low value-to-weight ratio and is highly perishable—it absolutely must be discharged from the truck before it hardens. These transportation barriers mean ready-mixed concrete must be produced near its customers. For the same reason, foreign trade in ready-mixed concrete is essentially nonexistent. This article is an introduction to the basics of the market for ready-mix concrete, focusing mainly on its consumers and its producers in the United States, but with occasional comparisons to other countries when contrasts are useful.
The Productivity Gap between Europe and the United States: Trends and Causes
Authors: van Ark Bart , O'Mahony Mary , Timmer Marcel P
Published: February 2008

Since the mid-1990s, labor productivity growth in Europe has significantly slowed compared to earlier decades. In contrast, labor productivity growth in the United States accelerated, so that a new productivity gap has opened up. This paper shows that this development is attributable to the slower emergence of the knowledge economy in Europe. We consider various explanations which are not mutually exclusive. These include lower growth contributions from investment in information and communication technology; the small share of information and communications technology–producing industries in Europe; and slower multifactor productivity growth, which proxies for advances in technology and innovation. Underlying these are issues related to the functioning of European labor markets and the high level of product market regulation in Europe. The paper emphasizes the key role of market service sectors in accounting for the productivity growth divergence between the two regions. We argue that improved productivity growth in Europe's market services will be needed to avoid a further widening of the productivity gap.
Ligand-dependent folding of the three-way junction in the purine riboswitch
Authors: Stoddard Colby D , Gilbert Sunny D. , Batey Robert T.
Published: February 2008

Riboswitches are highly structured cis-acting elements located in the 5′-untranslated region of messenger RNAs that directly bind small molecule metabolites to regulate gene expression. Structural and biochemical studies have revealed riboswitches experience significant ligand-dependent conformational changes that are coupled to regulation. To monitor the coupling of ligand binding and RNA folding within the aptamer domain of the purine riboswitch, we have chemically probed the RNA with N-methylisatoic anhydride (NMIA) over a broad temperature range. Analysis of the temperature-dependent reactivity of the RNA in the presence and absence of hypoxanthine reveals that a limited set of nucleotides within the binding pocket change their conformation in response to ligand binding. Our data demonstrate that a distal loop–loop interaction serves to restrict the conformational freedom of a significant portion of the three-way junction, thereby promoting ligand binding under physiological conditions.
Translational repression during chronic hypoxia is dependent on glucose levels
Authors: Thomas Jeff D. , Dias Lizalynn M. , Johannes Gregg J.
Published: February 2008

Translation is often repressed in cell lines that are exposed to hypoxic conditions (0.5% – 1.5% O2) but this repression requires prolonged exposure (> 16 h). We report here that prolonged exposure to hypoxia results in the depletion of glucose from the media and that the loss of glucose correlates with the shut down in translation. Furthermore, we show that the addition of glucose or reoxygenation restores translation in hypoxic PC3 cells. This indicates that both glucose depletion and hypoxia are required for translational repression. We also show that eIF2α phosphorylation is reversed by glucose addition. Moreover, we present data that strongly indicate that eIF2α phosphorylation as well as the translational inhibition that occurs when cells are grown under conditions of glucose depletion and hypoxia is pancreatic eIF2α kinase (PERK) independent. We believe this is the first report to show that glucose depletion is required for translational repression under hypoxic conditions and that this explains why prolonged exposure to hypoxia is required for this inhibition. Since the physiological conditions that lead to tumor hypoxia would also likely lead to reduced glucose levels, understanding the interplay of glucose and hypoxia in regulating tumor metabolism will provide important information on the growth and development of solid tumors.
Decreased aminoacylation in pathology-related mutants of mitochondrial tRNATyr is associated with structural perturbations in tRNA architecture
Authors: Bonnefond Luc , Florentz Catherine , Giegé Richard , Rudinger-Thirion Joëlle
Published: February 2008

A growing number of human pathologies are ascribed to mutations in mitochondrial tRNA genes. Here, we report biochemical investigations on three mt-tRNATyr molecules with point substitutions associated with diseases. The mutations occur in the atypical T- and D-loops at positions homologous to those involved in the tertiary interaction network of canonical tRNAs. They do not correspond to tyrosine identity positions and likely do not contact the mitochondrial tyrosyl-tRNA synthetase during the aminoacylation process. The impact of these substitutions on mt-tRNATyr tyrosylation and structure was investigated using the corresponding tRNA transcripts. In vitro tyrosylation efficiency is decreased 600-fold for mutant A22G (mitochondrial gene mutation T5874C), 40-fold for G15A (C5877T), and is without significant effect on U54C (A5843G). Comparative solution probings with lead and nucleases on mutant and wild-type tRNATyr molecules reveal a greater sensitivity to single-strand specific probes for mutants G15A and A22G. For both transcripts, the mutation triggers a structural destabilization in the D-loop that propagates toward the anticodon arm and thus hinders efficient tyrosylation. Further probing analysis combined with phylogenetic data support the participation of G15 and A22 in the tertiary network of human mt-tRNATyr via nonclassical Watson–Crick G15–C48 and G13–A22 pairings. In contrast, the pathogenic effect of the tyrosylable mutant U54C, where structure is only marginally affected, has to be sought at another level of the tRNATyr life cycle.
The Impact of Simulation Training on Call Center Agent Performance: A Field-Based Investigation
Authors: Murthy Nagesh N. , Challagalla Goutam N. , Vincent Leslie H. , Shervani Tasadduq A.
Published: February 2008

The most prevalent form of training call center agents is via classroom instruction coupled with role-plays. Role-play training has a theoretical base in behavior modeling that entails observation, practice, and feedback. Emerging simulation-based technologies offer enhancements to behavior modeling that are absent in role-play training. This study evaluates the effectiveness of simulation-based training (henceforth, simulation training) as a behavior modeling technique vis-à-vis role-play training in a real-world call center environment across tasks of different levels of complexity. We collaborate with call centers at two Fortune 50 firms and examine on-job performance metrics to evaluate the effectiveness of simulation training. The performance measures of interest are call accuracy and call duration because these are two important factors that influence customer satisfaction and productivity in call center operations. After controlling for factors such as trainee's learning and technology orientation, age, education, and call center experience, results show that simulation training outperforms role-playing-based training in terms of both accuracy and speed of processing customer calls. Further, the relative superiority of simulation training improves at higher levels of task complexity.
Staffing Multiskill Call Centers via Linear Programming and Simulation
Authors: Cezik Mehmet Tolga , L'Ecuyer Pierre
Published: February 2008

We study an iterative cutting-plane algorithm on an integer program for minimizing the staffing costs of a multiskill call center subject to service-level requirements that are estimated by simulation. We solve a sample average version of the problem, where the service levels are expressed as functions of the staffing for a fixed sequence of random numbers driving the simulation. An optimal solution of this sample problem is also an optimal solution to the original problem when the sample size is large enough. Several difficulties are encountered when solving the sample problem, especially for large problem instances, and we propose practical heuristics to deal with these difficulties. We report numerical experiments with examples of different sizes. The largest example corresponds to a real-life call center with 65 types of calls and 89 types of agents (skill groups).
Drivers and Performance Outcomes of Trust in International Strategic Alliances: The Role of Organizational Complexity
Authors: Robson Matthew J. , Katsikeas Constantine S. , Bello Daniel C.
Published: February 2008

Trust between partners has become a key construct in interfirm relationship management. However, elucidating the precise nature of the trust-performance link in international strategic alliances remains an important theoretical and empirical challenge for management scholars. Discordant findings evident in existing alliance research raise concerns that interpartner trust does not always enhance venture performance. To investigate this issue, we build and test a theoretical framework that integrates different perspectives of alliance functioning by focusing on the social and bureaucratic forces critical to cooperative processes. The model (1) identifies organizational complexity mechanisms underlying the development of trust in international strategic alliances, (2) points to alliance size as an important factor that conditions the trust-performance relationship, (3) incorporates a new, third-order conceptualization of interpartner trust in alliances, and (4) suggests a theory-based multidimensional assessment of alliance performance. Based on data collected through personal interviews in 177 international strategic alliances, the results suggest that, while interpartner trust is positively associated with alliance performance, this relationship becomes stronger when alliance size declines. We find that both distributive fairness and partner similarity are central to the achievement of a trusting alliance partnership. Managerial insights into developing successful trust-based international alliance exchanges are offered, and fruitful avenues of research are discussed.
Néron models and compactified Picard schemes over the moduli stack of stable curves
Authors: Caporaso Lucia
Published: February 2008

We construct modular Deligne-Mumford stacks representable over parametrizing Néron models of Jacobians as follows. Let B be a smooth curve and K its function field, let be a smooth genus-g curve over K admitting stable minimal model over B. The Néron model → B is then the base change of via the moduli map B → of f , i.e.: B. Moreover is compactified by a Deligne-Mumford stack over , giving a completion of Néron models naturally stratified in terms of Néron models.
Radial Limits of Quasiregular Local Homeomorphisms
Authors: Rajala Kai
Published: February 2008

We study the boundary behavior of spatial quasiregular local homeomorphisms defined on the unit ball. We show that such maps always have radial limits at some boundary points. This result is new also in the case of bounded maps. The result fails for (unbounded) planar maps.
Isophasal, isopolar, and isospectral Schrödinger operators and elementary complex analysis
Authors: Christiansen T
Published: February 2008

We explicitly construct super-exponentially decaying potentials on d so that
the associated Schrödinger operators are isophasal and isopolar. We use similar
techniques to construct isospectral Schrödinger operators with periodic potentials
on and isospectral Schrödinger operators on 1.
Integral Geometry of Tensor Fields on a Class of Non-Simple Riemannian Manifolds
Authors: Stefanov Plamen , Uhlmann Gunther
Published: February 2008

We study the geodesic X-ray transform IΓ of tensor fields on a compact Riemannian manifold M with non-necessarily convex boundary and with possible conjugate points. We assume that IΓ is known for geodesics belonging to an open set Γ with endpoints on the boundary. We prove generic s-injectivity and a stability estimate under some topological assumptions and under the condition that for any ( x, ξ ) ∈ T*M , there is a geodesic in Γ through x normal to ξ without conjugate points.
Belyi's theorem for complex surfaces
Authors: González-Diez Gabino
Published: February 2008

Belyi's theorem states that a compact Riemann surface C can be defined over a number
field if and only if there is on it a meromorphic function f with three critical
values. Such functions (resp. Riemann surfaces) are called Belyi functions
(resp. Belyi surfaces). Alternatively Belyi surfaces can be characterized as
those which contain a proper Zariski open subset uniformised by a torsion free
subgroup of the classical modular group SL2(Z). In this article
we establish a result analogous to Belyi's theorem in complex dimension two. It turns
out that the role of Belyi functions is now played by (composed) Lefschetz
pencils with three critical values while the analogous to torsion free subgroups of
the modular group will be certain extensions of them acting on a Bergmann
domain of 2. These groups were first introduced by Bers and Griffiths.
Un CritÈre de LaminaritÉ Locale en Dimension Quelconque
Authors: ThÉLin Henry De
Published: February 2008

Nous montrons qu'une suite de sous-ensembles analytiques lisses de dimension pure s de la boule unité de C l , dont la courbure est contrôlée par le volume, converge vers une lamination de dimension s dans un sens faible.
On Maass lifts and the central critical values of triple product L -functions
Authors: Ichino Atsushi , Ikeda Tamotsu
Published: February 2008

We express certain period integrals of Maass lifts which appear in the Gross-Prasad
conjecture in terms of the central critical values of triple product L-functions in
the imbalanced case.
Constructibility and duality for simple holonomic modules on complex symplectic manifolds
Authors: Kashiwara Masaki , Schapira Pierre
Published: February 2008

Consider a complex symplectic manifold and the algebroid stack of deformation-quantization. For two regular holonomic -modules (i=0,1) supported by smooth Lagrangian
submanifolds, we prove that the complex is perverse over the field and dual to the
complex .
Projective Surface Automorphisms of Positive Topological Entropy from an Arithmetic Viewpoint
Authors: Kawaguchi Shu
Published: February 2008

Let X be a smooth projective surface over a number field K ([inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="01i"/] C), and f : X → X an automorphism of positive topological entropy. In this paper, we show that there are only finitely many f -periodic curves on X . Then we define a height function ĥ D corresponding to a certain nef and big R-divisor D on X and transforming well relative to f , and deduce some arithmetic properties of f -periodic points and non f -periodic points.
Global Solutions of Quasilinear Wave Equations
Authors: Lindblad Hans
Published: February 2008

We show global small data existence for a class of quasilinear wave equations related to Einstein's equations in harmonic coordinates. These equations do not satisfy the classical null condition and the asymptotic behavior of solutions is not free but the light cones bend at infinity.
Age and Race/Ethnicity-Gender Predictors of Denying Smoking, United States
Authors: Fisher Monica A. , Taylor George W. , Shelton Brent J. , Debanne Sara
Published: February 2008

Smoking is a major risk factor for many chronic diseases. Nearly all studies collecting smoking data use self-reports, which are very rarely validated. We identified 15,182 adults 18 years or older in the Third National Health and Nutrition Examination Survey. Denying smoking, the main outcome, was defined as cotinine-determined smokers self-reporting non-smoking. Multiple logistic regression modeling took into account the complex survey design and sample weights. Age and race/ethnicity-gender categories predicted denying smoking. Smokers denying smoking ranged from 0.0% for elderly (75 years and older) Mexican-American women to 67.8% for elderly non-Hispanic Black women. Among elderly smokers, non-Hispanic Black women were more likely to deny smoking than both non-Hispanic White women (odds ratio (OR) = 8.9, 95% confidence interval (CI): 2.1–38.3) and non-Hispanic Black men (OR=21.4 95% CI: 4.3–107.2). This U.S. population-based study of age-specific race/ethnicity-gender predictors of denying smoking suggests caution in interpreting smoking-related survey data.
Predictors of Cancer Screening Among Low-Income Primary Care Patients
Authors: Lubetkin Erica I. , Santana Annabel , Tso Alan , Jia Haomiao
Published: February 2008

Although population-based studies report lower rates of cancer screening among racial/ethnic minorities than among Whites in the U.S., few studies have examined predictors of screening among low-income Hispanic, Black, and Chinese primary care patients. We examined utilization of mammography, Pap smear, digital rectal examination, fecal occult blood testing, sigmoidoscopy/colonoscopy, and prostate-specific antigen testing in 833 patients from 2 community health centers in New York City, ascertaining relationships between use of screening and race/ethnicity, income, education, years in the U.S., insurance, cancer risk perception, family disease history, and physician recommendation. Despite similar access to primary care, Hispanics and Blacks reported higher utilization rates of all screening tests than Chinese (p<.01). Physician recommendation and more years in the U.S. were associated with greater use of all screening services (p<.001), with physician recommendation most strongly associated with screening. Interventions to enhance screening by at-risk groups should emphasize both physician recommendation and culturally-sensitive patient education.
Quality of Anticoagulation Control: Do Race and Language Matter?
Authors: Bhandari Vijay K. , Wang Frances , Bindman Andrew B. , Schillinger Dean
Published: February 2008

No studies have evaluated the quality of anticoagulation control among populations characterized by low socioeconomic status, diverse racial and ethnic backgrounds, or limited English proficiency. We conducted a retrospective cohort study to evaluate the effects of race/ethnicity and language on anticoagulation outcomes among patients (N=864) receiving continuous anticoagulation services at a university-affiliated public hospital. White/non-Hispanic patients made up 24%, Asian/Pacific Islanders 33%, Hispanics 22%, African Americans 18%. English (63%), Spanish, (14%), and Cantonese (13%) were the most common languages. Mean time in therapeutic range (TTR) was 43%. After adjustment, TTR was lower for African Americans than for Whites (absolute difference, –8.7%, p<.001) and for Spanish-speaking than for English-speaking Hispanics (absolute difference, –7.2%, p<.05). There were no differences between Asian/Pacific Islanders and Whites, nor between Cantonese-speaking and English-speaking Asian/Pacific Islanders. Future research should examine mechanisms by which race/ethnicity and language affect quality of anticoagulation and evaluate programs to improve treatment in diverse communities.
Systematic Prenatal Screening for Psychosocial Risks
Authors: Harrison Patricia A. , Sidebottom Abbey C.
Published: February 2008

The Prenatal Risk Overview (PRO) was designed to screen for 13 psychosocial risk factors associated with poor birth outcomes. This study describes the development and implementation of the PRO in 4 community health centers. The study also examines the prevalence, co-occurrence, and inter-correlations of psychosocial risks in their prenatal populations. The study sample included 1,386 prenatal patients screened between November 2005 and April 2007; 95% were women of color; 77% were not married. The PRO classified 48% at moderate or high risk for housing instability; 32% for food insecurity; 75% for lack of social support; 7% for intimate partner violence; 9% for other physical/sexual abuse; 18% for depression; 23% for cigarette use, 23% for alcohol use, and 25% for drug use. Systematically assessing and quantifying psychosocial risks are essential activities for evaluating the extent to which appropriate and timely responses to identified risks reduce infant mortality, preterm births, and low birth weights.
The Effects of Perceived Discrimination on Diabetes Management
Authors: Ryan Andrew M. , Gee Gilbert C. , Griffith Derek
Published: February 2008

We investigated whether self-reported racial/ethnic and gender discrimination were associated with lower rates of diabetes management. Analyses focused on 524 respondents with diabetes from the 2001 Commonwealth Health Care Quality Survey. Probit models estimated the marginal effect of self-reported racial/ethnic and gender discrimination on diabetes management, adjusting for racial/ethnic and gender concordance of the patient and physician, as well as a variety of health and sociodemographic indicators. Self-reported racial/ethnic discrimination was associated with a roughly 50% lower marginal probability of receiving a hemoglobin A1c test, foot exam, and blood pressure exam, when accounting for racial/ethnic and gender physician-patient concordance and other factors. Self-reported gender discrimination was associated with 22% lower marginal probability of conducting a hemoglobin test but not associated with the other management indicators. Evidence from this study suggests that racial/ethnic discrimination is an important barrier to diabetes management.
Ethnic Differences and Treatment Trajectories in Chronic Kidney Disease
Authors: Johnson Sara , Sidelinger Dean E. , Blanco Estela , Palinkas Lawrence A. , Macdonald Dina , Reznik Vivian
Published: February 2008

Little is known about barriers to care experienced by Latino children with chronic kidney disease (CKD). We conducted a qualitative study with children with CKD and their families to elucidate conceptions about disease process, expression, and treatment; perceived access to care barriers; and potential for treatment non-adherence. Semi-structured interviews were conducted with 42 individuals from 28 family units treated for CKD in San Diego, California. Transcripts were analyzed by coding consensus, co-occurrence, and comparison. Latino patients cited pre-diagnosis barriers in accessing primary and subspecialty care not mentioned by non-Latino Whites. Whites described a pro-active style of interacting with the health care system not mentioned by Latinos. There were no differences apparent in reports of medication adherence, but both groups emphasized the importance of extended social networks in adhering to treatment regimens. Families’ perspectives provide valuable information that can serve future studies and interventions for improving care for children with CKD.
Children’s Mental Health Care: Differences by Race/Ethnicity in Urban/Rural Areas
Authors: Howell Embry , McFeeters Joshua
Published: February 2008

This study examines racial/ethnic disparities in children’s mental health and the receipt of mental health services, and whether those disparities differ between urban and rural areas. We find no significant difference between racial/ethnic groups in the prevalence of child mental health problems in either urban or rural areas. However, there are disparities in the use of mental health services. Hispanic children and Black children in urban areas receive less mental health care than their White counterparts, and the disparity persists for Hispanic children in rural areas, even after controlling for other relevant factors. Initiatives to improve access to mental health care for racial/ethnic minorities should recognize these disparities, and address the lack of culturally appropriate services in both urban and rural areas. In addition, outreach should raise awareness among parents, teachers, and other community members concerning the need for mental health services for minority children.
The Need for Diversity in the Environmental Health Workforce
Authors: Walker Bailus , Spann Melvin
Published: February 2008

Epidemiologic evidence makes clear that the likelihood of exposure to environmental contaminants increases in most poor and underserved communities. Despite progress in reducing a number of environmental risk factors for disease, serious environmental problems persist, and those remaining problems are highly complex. Their solution requires meaningful community engagement as well as a diverse environmental health workforce. Demographic data, and related social and economic developments, strongly indicate that such a workforce must include underrepresented minorities. While the problem has not been solved, select programs have made impressive contributions to meeting this need, an example of which is described in this paper.