bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation behaviour of aluminium during machining: Modelling by Eulerian and smoothed-particle hydrodynamics methods
Authors: Akarca S. S. , Song X. , Altenhof W. J , Alpas A. T 
Published: June 2008

Large-strain deformation behaviour of aluminium that accompanies continuous chip formation during machining (1100 Al) has been studied using experimental and numerical techniques. In experimental studies, local values of plastic strains were determined in the primary and the secondary deformation zones of machined 1100 Al. This was completed through a careful examination of metallographic sections taken from the material ahead of the tool tip, in which orientation changes in the flow lines in the material and shear angles were used to calculate plastic strains. Variations in local flow stresses were estimated from microhardness measurements. The examination of the stresses and strains at each measurement location generated a stress—strain relationship for the 1100 Al material. An important observation from the experimental portion of this research indicated that the material stress—strain response was independent of the feed rates considered in this study. Additionally, the response was observed to obey an exponential relationship with stress saturation occurring at approximately 300 MPa. Parameters associated with the Johnson—Cook constitutive equation were also determined from the experimental work. An Eulerian finite-element method and a relatively new so-called mesh-free method [smoothed-particle hydrodynamics (SPH) method] have been applied to the simulation of machining. The application of these methods permits simulation of the machining process without use of any mesh separation criterion. Appropriate values of the coefficients of friction, for numerical studies, were determined in parametric studies by correlating the experimentally measured chip thicknesses with the numerically predicted values. The effectiveness of the Eulerian and SPH methods in predicting the response of 1100 Al during orthogonal machining has been assessed through a rigorous comparison of the stress—strain distribution within formed chips during steady-state cutting. Both the Eulerian and SPH models showed good overall correlation with the experimentally measured stress—strain distribution when the exponential type material behaviour was assumed in modelling. A maximum stress of 300 MPa at the tool tip was obtained from the numerical simulations using the assumed exponential material behaviour. The location of maximum stress corresponded to the position of maximum strain (8.0). The application of the Johnson—Cook type constitutive equation resulted in predicting a lower maximum equivalent strain (4.5) and higher maximum stresses (325 MPa).
When Does Coordination Require Centralization? Corrigendum
Authors: Alonso Ricardo , Dessein Wouter , Matouschek Niko 
Published: June 2008

The equations on page 153 of “When Does Coordination Require Centralization?,” which appeared in the March 2008 issue of the American Economic Review, failed to print in their entirety. The complete text of Section III, Decision Making, appears below.
Stability in Supply Chain Networks
Authors: Ostrovsky Michael 
Published: June 2008

This paper studies matching in vertical networks, generalizing the theory of matching in two-sided markets. It gives sufficient conditions for the existence of stable networks and presents an algorithm for finding two of them. One is the best stable network for the agents on the “upstream” end of an industry. The other is best for the agents on the “downstream” end. The paper describes several properties of the set of stable networks and discusses applications of the theory to the design of matching markets with more than two types of agents and to the empirical analysis of supply chains. (JEL C78, D85, L14) The woollen coat, for example, which covers the day-labourer, as coarse and rough as it may appear, is the produce of the joint labour of a great multitude of workmen. The shepherd, the sorter of the wool, the wool-comber or carder, the dyer, the scribbler, the spinner, the weaver, the fuller, the dresser, with many others, must all join their different arts in order to complete even this homely production. —Adam Smith (1776)
FactSage and ChemApp: Two tools for the prediction of multiphase chemical equilibria in solutions
Authors: Eriksson Gunnar , Königsberger Erich 
Published: June 2008

Abstract
The integrated thermochemical databank system FactSage enables the user to calculate equilibria and thermodynamic properties for a wide variety of multicomponent, multiphase systems and reactions. The Gibbs energy models and databases for condensed, gaseous, and aqueous solutions presently implemented in FactSage are of interest to chemical and physical metallurgy, chemical and corrosion engineering, inorganic and solution chemistry, geochemistry, environmental science, etc. Models for the aqueous phase include the Pitzer and Helgeson formalisms, but data and subroutines for concentrated aqueous solutions have also been provided by OLI Systems. ChemApp is a programmer's library for thermochemistry that also incorporates the Gibbs energy minimizer of FactSage. Applications of ChemApp include, for example, the handling of repetitive complex equilibrium calculations in application-specific programs and its linking to third-party process simulation packages. In this work, user-defined aqueous solution models in FactSage and ChemApp have been applied to the hydrometallurgical processing of aluminum ores in both caustic and acidic leach solutions.
Chemical speciation of polynuclear complexes containing [Ln2M3L6] units
Authors: Torres Julia , Kremer Carlos , Domínguez Sixto 
Published: June 2008

Abstract
Polynuclear complexes are widely regarded as potential materials in separation, catalysis, gas storage, and molecular recognition. Those complexes including lanthanide (Ln) ions in the heterobimetallic assembly enhance the structural flexibility and increase the thermodynamic stability. Up to now, the studies on these heteropolynuclear complexes have been mostly focused on lanthanide-copper compounds in the solid state. We have expanded the studies to solution chemistry, to know if such polynuclear species can also exist in aqueous solution. In this work, potentiometric titrations (25.0 °C, and I = 0.50 M Me4NCl) were carried out for systems containing a Ln ion (La, Ce, Sm), a bridging ligand (oda or ida), and a second metal ion. We found that polynuclear units can be formed with MII (Mn, Fe, Co, Ni, Cu, Zn, Cd, and VO2+) and MIII (Fe, Al) ions, and can be predominant in aqueous solution. Species like [Ln2M3L6] or [Ln2M3L6(OH)
n
]
n-
(n = 3, 6) can exist in solution, representing the same 2:3:6 stoichiometry found in the solid state. The presence of an amino group in the ida ligand makes the mononuclear complexes with 3d metal ions more stable, preventing to some extent the formation of polynuclear complexes.
Potential of Sterol Analysis by Liquid Chromatography–Tandem Mass Spectrometry for the Prenatal Diagnosis of Smith-Lemli-Opitz Syndrome
Authors: Griffiths William J , Wang Yuqin , Karu Kersti , Samuel Emmanuel , McDonnell Shane , Hornshaw Martin , Shackleton Cedric 
Published: June 2008

AbstractBackground: Smith-Lemli-Opitz syndrome (SLOS), a severe disorder of cholesterol synthesis, is classically diagnosed prenatally by GC-MS analysis of sterols in amniotic fluid. Considering the current trend toward tandem mass spectrometry (MS/MS) methodologies, we developed prototype LC-MS/MS methods for accurate diagnosis of the disorder.Methods: 3β-Hydroxysterols in amniotic fluid are oxidized with cholesterol oxidase to their corresponding 3-ketones, which are then derivatized with Girard P (GP) hydrazine in a “one-pot” reaction. The resulting GP-hydrazones give an improved response in electrospray (ES)–MS/MS owing to the presence of a charged quaternary nitrogen and are analyzed by reversed-phase LC-ES-MS/MS. Both capillary and conventional LC-MS/MS formats are suitable, and the method is also applicable to paper-absorbed blood spots.Results: In a double-blind analysis of 18 amniotic fluid samples comprising 6 SLOS and 12 controls, the ratio of 7 + 8-dehydrocholesterol (7 + 8-DHC) to cholesterol was &lt;0.02 [range 0.00–0.02, mean (SD) 0.01 (0.007)] in all control samples (intraassay variation 5.91%) and &gt;0.20 [0.20–1.13, 0.79 (0.35)] in SLOS (intraassay variation 4.56%), corresponding to a difference in ratios between the 2 groups of at least a factor of 10. The limit of quantification was equivalent to that of 2 nL amniotic fluid injected on-column.Conclusions: We describe a proof-of-concept for the prenatal diagnosis of SLOS. Further developments will be necessary to automate sample handling and reduce chromatographic time for the methodology to be used in pre- and postnatal diagnosis.
Extremal lengths of homology classes on Riemann surfaces
Authors: Masumoto Makoto 
Published: June 2008

Abstract
We assign a positive number V, a new conformal invariant, to a Riemann surface R of finite genus in terms of the extremal lengths of certain weak homology classes on R, and determine the range of V. In particular we find algebraic relations among the extremal lengths of homology classes on compact Riemann surfaces.
Dendritische Zellen und Immunsuppression nach Organtransplantation / Dendritic cells and immunosuppression after organ transplantation
Authors: Daniel Volker 
Published: June 2008

Zusammenfassung
Die dendritsche Zelle (DC) steht am Anfang jeder Immunreaktion. Sie kann eine Immunreaktion gegen Fremdantigene einleiten oder unterdrücken. Ihre diagnostische und therapeutische Nutzbarmachung ist Forschungsgegenstand der Transplantationsmedizin. Ein Ziel transplantationsimmunologischer Studien ist die Identifikation von organtransplantierten Patienten, deren immunsuppressive Medikation ohne Beeinträchtigung der Transplantatfunktion reduziert, eventuell sogar abgesetzt werden kann. Die Induktion von tolerogenen DCs und deren immunologische Überwachung im Blut des Patienten wären eine Option zur Realisierung dieses Ziels. In Zellkultur- und Tierexperimenten konnten DCs als Zielzellen von immunsuppressiv wirkenden Medikamenten identifiziert werden. Klinische Studien mit organtransplantierten Patienten zeigten Veränderungen verschiedener DC-Subpopulationen im Blut der Patienten in Abhängigkeit von der immunsuppressiven Medikation und ihrer Dosierung. Bislang konnte keine DC-Subpopulation im Blut von organtransplantierten Patienten identifiziert werden, die prospektiv ein Absetzen der Immunsuppressiva erlauben würde. Weitere Untersuchungen an DC-Subpopulationen in vitro und in vivo sind notwendig, um die für die Induktion und Aufrechterhaltung einer Immuntoleranz relevanten DCs definieren zu können.
Canonical Wnt Signaling Controls Proliferation of Retinal Stem/Progenitor Cells in Postembryonic Xenopus Eyes
Authors: Denayer Tinneke , Locker Morgane , Borday Caroline , Deroo Tom , Janssens Sylvie , Hecht Andreas , van Roy Frans , Perron Muriel , Vleminckx Kris 
Published: June 2008

Abstract
Vertebrate retinal stem cells, which reside quiescently within the ciliary margin, may offer a possibility for treatment of degenerative retinopathies. The highly proliferative retinal precursor cells in Xenopus eyes are confined to the most peripheral region, called the ciliary marginal zone (CMZ). Although the canonical Wnt pathway has been implicated in the developing retina of different species, little is known about its involvement in postembryonic retinas. Using a green fluorescent protein-based Wnt-responsive reporter, we show that in transgenic Xenopus tadpoles, the canonical Wnt signaling is activated in the postembryonic CMZ. To further investigate the functional implications of this, we generated transgenic, hormone-inducible canonical Wnt pathway activating and repressing systems, which are directed to specifically intersect at the nuclear endpoint of transcriptional Wnt target gene activation. We found that postembryonic induction of the canonical Wnt pathway in transgenic retinas resulted in increased proliferation in the CMZ compartment. This is most likely due to delayed cell cycle exit, as inferred from a pulse-chase experiment on 5-bromo-2′-deoxyuridine-labeled retinal precursors. Conversely, repression of the canonical Wnt pathway inhibited proliferation of CMZ cells. Neither activation nor repression of the Wnt pathway affected the differentiated cells in the central retina. We conclude that even at postembryonic stages, the canonical Wnt signaling pathway continues to have a major function in promoting proliferation and maintaining retinal stem cells. These findings may contribute to the eventual design of vertebrate, stem cell-based retinal therapies.
Disclosure of potential conflicts of interest is found at the end of this article.
Fate Mapping and Lineage Analyses Demonstrate the Production of a Large Number of Striatal Neuroblasts After Transforming Growth Factor α and Noggin Striatal Infusions into the Dopamine-Depleted Striatum
Authors: de Chevigny Antoine , Cooper Oliver , Vinuela Angel , Reske-Nielsen Casper , Lagace Diane C. , Eisch Amelia J. , Isacson Ole 
Published: June 2008

Abstract
Infusion of transforming growth factor α (TGFα) into the adult dopamine (DA)-depleted striatum generates a local population of nestin+/proliferating cell nuclear antigen (PCNA)+ newborn cells. The precise origin and fate of these new striatal cells are unknown, making it difficult to direct them for neural repair in Parkinson's disease. Experiments in rats using 5-bromo-2′-deoxyuridine (BrdU) to label neural progenitor cells showed that during TGFα infusion in the DA-depleted striatum, newborn striatal cells formed a homogeneous population of precursors, with the majority coexpressing nestin, Mash1, Olig2, and epidermal growth factor receptor, consistent with the phenotype of multipotent C cells. Upon TGFα pump withdrawal, the subventricular zone (SVZ) was repopulated by neuroblasts. Strikingly, during this period, numerous clusters of doublecortin+/polysialylated neuronal cell adhesion molecule+ neuroblasts were also produced in the ipsilateral medial striatum. In parallel, striatal BrdU+/glial fibrillary acidic protein+ astrocytes were generated, but no BrdU+/O4+/CNPase+ oligodendrocytes were generated. Infusion of the neuralizing bone morphogenetic protein antagonist noggin after TGFα pump withdrawal increased the neuroblast-to-astrocyte ratio among new striatal cells by blocking glial differentiation but did not alter striatal neurogenesis. At no time or treatment condition were differentiated neurons generated, including DA neurons. Using 6-hydroxydopamine-lesioned nestin-CreERT2/R26R-YFP mice that allow genetic fate-mapping of SVZ nestin+ cells, we show that TGFα-generated striatal cells originate from SVZ nestin+ precursors that confirmed data from the rats on the phenotype and fate of striatal nestin+/PCNA+ cells upon TGFα withdrawal. This work demonstrates that a large population of multipotent striatal C-like cells can be generated in the DA-depleted striatum that do not spontaneously differentiate into DA neurons.
Disclosure of potential conflicts of interest is found at the end of this article.
TIS21/BTG2 Negatively Regulates Estradiol-Stimulated Expansion of Hematopoietic Stem Cells by Derepressing Akt Phosphorylation and Inhibiting mTOR Signal Transduction
Authors: Kim Bong Cho , Ryu Min Sook , Oh S. Paul , Lim In Kyoung 
Published: June 2008

AbstractIt has been known that 12-O-tetradecanoyl phorbol-13-acetate-inducible sequence 21 (TIS21), ortholog of human B-cell translocation gene 2, regulates expansions of stage-specific thymocytes and hematopoietic progenitors. In the present study, lineage-negative (Lin−)/stem cell antigen-1-positive (Sca-1+)/c-Kit+ (LSK) cell content was significantly elevated in bone marrow (BM) of TIS21-knockout (TIS21−/−) female mice, suggesting 17β-estradiol (E2)-regulated progenitor expansion. E2 induced DNA synthesis and cell proliferation of mouse embryonic fibroblasts (MEFs) isolated from TIS21−/− mice, but not wild type (WT). In contrast to WT, E2 failed to activate protein kinase B (Akt) in the TIS21−/− MEFs, independent of extracellular signal-regulated kinase 1/2 (Erk1/2) activation. Despite attenuation of Akt activation, mammalian target of rapamycin (mTOR) was constitutively activated in the TIS21−/− MEFs. Furthermore, mitogen-activated protein kinase 1/2 inhibitor or knockdown of Erk1 could restore activation of Akt and downregulate mTOR. Immunoprecipitation showed Akt preferentially bound to phosphorylated Erk1/2 (p-Erk1/2) in TIS21−/− cells, but reconstitution of TIS21 inhibited their interaction. E2-injected TIS21−/− male mice also increased LSK cells in BM. Taken together, expansion of hematopoietic progenitors in TIS21−/− female mice might be through inhibition of Akt activation, and constitutive activation of mTOR via preferential binding of TIS21 to E2-induced p-Erk1/2, compared with that of Akt. Our results suggest that TIS21 plays a pivotal role in maintaining the hematopoietic stem cell compartment and hematopoiesis.Disclosure of potential conflicts of interest is found at the end of this article.
A Comparison of Regression Approaches for Analyzing Clustered Data
Authors: Desai Manisha , Begg Melissa D. 
Published: June 2008

Objectives. We used 3 approaches to analyzing clustered data to assess the impact of model choice on interpretation. Methods. Approaches 1 and 2 specified random intercept models but differed in standard versus novel specification of covariates, which impacts ability to separate within- and between-cluster effects. Approach 3 was based on standard analysis of paired differences. We applied these methods to data from the National Collaborative Perinatal Project to examine the association between head circumference at birth and intelligence (IQ) at age 7 years. Results. Approach 1, which ignored within- and between-family effects, yielded an overall IQ effect of 1.1 points (95% confidence interval [CI]=0.9, 1.3) for every 1-cm increase in head circumference. Approaches 2 and 3 found comparable within-family effects of 0.6 points (95% CI = 0.4, 0.9) and 0.69 points (95% CI = 0.4, 1.0), respectively. Conclusions. Our findings confirm the importance of applying appropriate analytic methods to clustered data, as well as the need for careful covariate specification in regression modeling. Method choice should be informed by the level of interest in cluster-level effects and item-level effects.
A Randomized Controlled Trial for Reducing Risks for Sexually Transmitted Infections Through Enhanced Patient-Based Partner Notification
Authors: Wilson Tracey E. , Hogben Matthew , Malka Edmond S. , Liddon Nicole , McCormack William M. , Rubin Steve R. , Augenbraun Michael A. 
Published: June 2008

Objectives. We sought to assess the effectiveness of approaches targeting improved sexually transmitted infection (STI) sexual partner notification through patient referral. Methods. From January 2002 through December 2004, 600 patients with Neisseria gonorrhoeae or Chlamydia trachomatis were recruited from STI clinics and randomly assigned to either a standard-of-care group or a group that was counseled at the time of diagnosis and given additional follow-up contact. Participants completed an interview at baseline, 1 month, and 6 months and were checked at 6 months for gonorrhea or chlamydial infection via nucleic acid amplification testing of urine. Results. Program participants were more likely to report sexual partner notification at 1 month (86% control, 92% intervention; adjusted odds ratio [AOR] = 1.8; 95% confidence interval [CI] = 1.02, 3.0) and were more likely to report no unprotected sexual intercourse at 6 months (38% control, 48% intervention; AOR = 1.5; 95% CI = 1.1, 2.1). Gonorrhea or chlamydial infection was detected in 6% of intervention and 11% of control participants at follow-up (AOR = 2.2; 95% CI = 1.1, 4.1), with greatest benefits seen among men (for gender interaction, P = .03). Conclusions. This patient-based sexual partner notification program can help reduce risks for subsequent STIs among urban, minority patients presenting for care at STI clinics.
The Role of Neighborhood Environment and Risk of Intimate Partner Femicide in a Large Urban Area
Authors: Frye Victoria , Galea Sandro , Tracy Melissa , Bucciarelli Angela , Putnam Sara , Wilt Susan 
Published: June 2008

Objectives. We evaluated the contribution of neighborhood-level factors indicative of social disorganization, including educational and occupational attainment, immigrant concentration, physical disorder, and social cohesion, to the likelihood of intimate partner femicide (IPF) while taking into account known neighborhood- and individual-level IPF risk factors. Methods. We used medical examiner data on 1861 femicide victims between 1990 and 1999 and archival information on 59 neighborhoods in New York City to conduct a multilevel case–control analysis. Results. After controlling for neighborhood-level income, we found that no neighborhood factors were significantly associated with IPF risk, as compared with risk of non–IPF and risk of femicide from unknown perpetrators, above and beyond the contributions of individual-level factors. The strongest predictors of IPF were foreign country of birth and young age. Conclusions. IPF victims were nearly twice as likely as non-IPF victims to be foreign born; by contrast, there was little neighborhood-level heterogeneity with respect to IPF risk. Further research is needed to identify neighborhood characteristics that uniquely influence risk of IPF to guide community-level interventions.
Adverse Event Detection in Drug Development: Recommendations and Obligations Beyond Phase 3
Authors: Berlin Jesse A. , Glasser Susan C. , Ellenberg Susan S. 
Published: June 2008

Premarketing studies of drugs, although large enough to demonstrate efficacy and detect common adverse events, cannot reliably detect an increased incidence of rare adverse events or events with significant latency. For most drugs, only about 500 to 3000 participants are studied, for relatively short durations, before a drug is marketed. Systems for assessment of postmarketing adverse events include spontaneous reports, computerized claims or medical record databases, and formal postmarketing studies. We briefly review the strengths and limitations of each. Postmarketing surveillance is essential for developing a full understanding of the balance between benefits and adverse effects. More work is needed in analysis of data from spontaneous reports of adverse effects and automated databases, design of ad hoc studies, and design of economically feasible large randomized studies.
The Influence of Educational Attainment on Depression and Risk of Type 2 Diabetes
Authors: Mezuk Briana , Eaton William W. , Golden Sherita Hill , Ding Yulan 
Published: June 2008

Objectives. We investigated the association between major depressive disorder and type 2 diabetes, whether that association is explained by health behaviors, and whether it is influenced by educational attainment. Methods. We used discrete-time Cox proportional hazards models to determine the risk of type 2 diabetes associated with depression in a 23-year population-based cohort study. Results. Major depressive disorder was associated with higher risk of type 2 diabetes (hazard ratio [HR]=1.62) after we controlled for age, gender, race, education, smoking status, alcohol use, social network size, and antidepressant use. This association was more pronounced after we controlled for body mass index, family history, and health behaviors (HR=2.04; 95% confidence interval=1.09, 3.81). In stratified analyses, the risk associated with major depressive disorder was elevated among those with 12 or fewer years of education compared with those with at least some education beyond high school. Conclusions. The risk of type 2 diabetes associated with major depressive disorder persists over the life course and is independent of the effects of health behaviors, body mass index, and family history. Education is an important moderator of this association.