bluuebunny/crossref_metadata_2025_split huggingface dataset:
Optimization of process parameters in wire electrical discharge machining of TiB2 nanocomposite ceramic
Authors: Amini H , Soleymani Yazdi M R , Dehghan G H 
Published: September 2011

Wire electrical discharge machining (WEDM) is a widely accepted non-traditional material removal process used to manufacture components with intricate shapes and profiles. The selection of optimum machining conditions for obtaining higher machining efficiency and increasing the accuracy of products are the most important task when the WEDM process is used for machining new advanced material such as nanocomposite ceramics. In this paper, a series of experiments has been carried out over a wide range of machining conditions. An L32 orthogonal array based on the Taguchi method for design of experiments is used to conduct the experiments. Then, by using a multilayer perceptron neural network, process modelling is performed and the most effective parameters on the process variables (i.e. material removal rate and surface roughness) are determined. Results demonstrate a very good modelling capacity of the proposed neural model. Finally, a genetic algorithm is used to optimize the process performance of WEDM. Additional experiments are performed to verify the adequacy of the optimization method. The optimization results are shown to be in good agreement with the experimental process outputs.
Mechanics of advanced materials for lightweight structures
Authors: Altenbach H 
Published: September 2011

In recent years, there have been a lot of new developments concerning the use of advanced materials for lightweight structures. Examples are long- and short-fibre-reinforced composites, sandwiches, foams, and, last but not least, nanostructures. The analysis of structures made of these materials can be performed on the basis of the Mechanics of Composites. However, stimulated by new applications, new manufacturing technologies, new material compositions, etc. a review of the Mechanics of Composites is necessary. In this article, some of the actual trends are discussed, for example developments in the application of long- and short-fibre-reinforced composites, laminates affected by multifield loadings, effective property-based analysis of foams, and the description of nanostructures within the concepts of Continuum Mechanics. The starting point of the review are the Engineering Mechanics basics on the level of the BSc program, that means the classical Strength of Materials. Extensions of Materials Strength foundations (for example, inclusion of anisotropy) are often sufficient as first improved estimates. If it is necessary, elements of Continuum Mechanics, of Material Testing or Numerical Solution Techniques can be implied. The every year increasing number of publications in the field of advanced materials for lightweight structures does not allow to give a complete overview over the state of the art. Recognizing this fact, the author will give a report only of directions related to his own research group and/or in the surrounding of his team.
Study of an upper arm exoskeleton for gravity balancing and minimization of transmitted forces
Authors: Dubey V N , Agrawal S K 
Published: September 2011

An upper-arm wearable exoskeleton has been designed for the assistance and functional training of humans. One of the goals of this design is to provide passive assistance to a user by gravity balancing, while keeping the transmitted forces to the shoulder joints at a minimum. Consistent with this goal, this paper discusses: analytical gravity balancing design conditions for the structure of the exoskeleton; a possible implementation of these conditions into practical designs; the minimization of transmitted joint forces to the shoulder while satisfying the gravity balancing conditions; the numerical optimization of the system for gravity balancing and minimization of transmitted forces; and the effect of parameter variation on joint moments and joint forces via numerical optimization. An implementation of the design was undertaken using zero-free-length springs. The design idea presented in this paper may be useful in relieving the actuators effort of exoskeletons to support the weight of the arm and therefore the possibility of using small actuators and making the system light and portable or even a stand-alone passive support device can be developed based on these gravity balancing conditions.
Beyond the intention-to-treat in comparative effectiveness research
Authors: Hernán Miguel A , Hernández-Díaz Sonia 
Published: September 2011

Background The intention-to-treat comparison is the primary, if not the only, analytic approach of many randomized clinical trials. Purpose To review the shortcomings of intention-to-treat analyses, and of ‘as treated’ and ‘per protocol’ analyses as commonly implemented, with an emphasis on problems that are especially relevant for comparative effectiveness research. Methods and Results In placebo-controlled randomized clinical trials, intention-to-treat analyses underestimate the treatment effect and are therefore nonconservative for both safety trials and noninferiority trials. In randomized clinical trials with an active comparator, intention-to-treat estimates can overestimate a treatment’s effect in the presence of differential adherence. In either case, there is no guarantee that an intention-to-treat analysis estimates the clinical effectiveness of treatment. Inverse probability weighting, g-estimation, and instrumental variable estimation can reduce the bias introduced by nonadherence and loss to follow-up in ‘as treated’ and ‘per protocol’ analyses. Limitations These analyse require untestable assumptions, a dose-response model, and time-varying data on confounders and adherence. Conclusions We recommend that all randomized clinical trials with substantial lack of adherence or loss to follow-up are analyzed using different methods. These include an intention-to-treat analysis to estimate the effect of assigned treatment and ‘as treated’ and ‘per protocol’ analyses to estimate the effect of treatment after appropriate adjustment via inverse probability weighting or g-estimation.
Ex vivo expansion of human Tregs specific for alloantigens presented directly or indirectly
Authors: Veerapathran Anandharaman , Pidala Joseph , Beato Francisca , Yu Xue-Zhong , Anasetti Claudio 
Published: September 2011

AbstractAdoptive transfer of regulatory T cells (Tregs) prevents GVHD in experimental animals. Because antigen activation drives Treg function, we measured the frequency, growth requirements, and function of alloantigen-specific (allospecific) Tregs from human blood. When alloantigen was presented directly, the precursor frequency of allo-specific Tregs in normal individuals was 1.02% (95% confidence interval [95% CI]: 0.65-1.59) and non-Tregs 1.56% (95% CI: 0.94-2.55). When alloantigen was presented indirectly, the frequency of specific Tregs was approximately 100-fold less. Purified Tregs were expanded with APCs, rapamycin, IL-2, and IL-15. In 12 days, allo-specific Tregs expanded 793-fold (95% CI: 480-1107), with duplication approximately every 24 hours. Purified allo-specific Tregs suppressed responses to specific alloantigen selectively and were approximately 100-fold more potent than polyspecific Tregs and nonexpanded Tregs. Allo-specific Tregs maintained high expression of Foxp3, Bcl-2, lymphoid homing receptor CD62L, and chemokine receptor CCR7, predicting sustained function and migration to lymphoid tissues in vivo. Allo-specific Tregs produced TGF-β and IL-10 and expressed more cytoplasmic CTLA-4 compared with non-Tregs. These data provide a platform for the selective expansion of Tregs against major and possibly minor histocompatibility antigens and predict the feasibility of adoptive immunotherapy trials using Tregs with indirect allo-recognition for preventing GVHD while sparing GVL effects.
Functional characterization of the Saccharomyces cerevisiae protein Chl1 reveals the role of sister chromatid cohesion in the maintenance of spindle length during S-phase arrest
Authors: Laha Suparna , Das Shankar P , Hajra Sujata , Sanyal Kaustuv , Sinha Pratima 
Published: September 2011

Abstract

Background
Metaphase cells have short spindles for efficient bi-orientation of chromosomes. The cohesin proteins hold sister chromatids together, creating Sister Chromatid Cohesion (SCC) that helps in the maintenance of short spindle lengths in metaphase. The budding yeast protein Chl1p, which has human homologs, is required for DNA damage repair, recombination, transcriptional silencing and aging. This protein is also needed to establish SCC between sister chromatids in S-phase.

Results
In the present study we have further characterized Chl1p for its role in the yeast Saccharomyces cerevisiae when cells are under replication stress. We show that when DNA replication is arrested by hydroxyurea (HU), the chl1 mutation causes growth deficiency and a mild loss in cell viability. Although both mutant and wild-type cells remained arrested with undivided nuclei, mutant cells had mitotic spindles, which were about 60-80% longer than wild-type spindles. Spindle extension occurred in S-phase in the presence of an active S-phase checkpoint pathway. Further, the chl1 mutant did not show any kinetochore-related defect that could have caused spindle extension. These cells were affected in the retention of SCC in that they had only about one-fourth of the normal levels of the cohesin subunit Scc1p at centromeres, which was sufficient to bi-orient the chromosomes. The mutant cells showed defects in SCC, both during its establishment in S-phase and in its maintenance in G2. Mutants with partial and pericentromeric cohesion defects also showed spindle elongation when arrested in S-phase by HU.

Conclusions
Our work shows that Chl1p is required for normal growth and cell viability in the presence of the replication block caused by HU. The absence of this protein does not, however, compromize the replication checkpoint pathway. Even though the chl1 mutation gives synthetic lethal interactions with kinetochore mutations, its absence does not affect kinetochore function; kinetochore-microtubule interactions remain unperturbed. Further, chl1 cells were found to lose SCC at centromeres in both S- and G2 phases, showing the requirement of Chl1p for the maintenance of cohesion in G2 phase of these cells. This work documents for the first time that SCC is an important determinant of spindle size in the yeast Saccharomyces cerevisiae when genotoxic agents cause S-phase arrest of cells.
In Vitro Assessment of Tobacco Smoke Toxicity at the BBB: Do Antioxidant Supplements Have a Protective Role?
Authors: Hossain Mohammed , Mazzone Peter , Tierney William , Cucullo Luca 
Published: September 2011

AbstractBackgroundTobacco smoke (TS) contains highly reactive oxygen species (such as hydrogen peroxide, peroxynitrite, etc), which cause oxidative damage in vascular tissue and may exacerbate inflammatory events leading to the blood-brain barrier damage (BBBD) which accompanies the development of a variety of neurological disorders. Smokers often have elevated leukocyte counts (primarily neutrophils and monocytes), and significant decreases in plasma alpha-tocopherol (vitamin E) and ascorbic acid (vitamin C) levels due to increased anti-oxidative mobilization in response to oxidative stress evoked by TS. For this purpose, using static culture systems and a well-established dynamicin vitroBBB model (DIV-BBB) we tested the hypothesis that antioxidant vitamin supplementation (E and/or C) can protect the BBB during exposure to whole soluble TS.ResultsTS exacerbates inflammatory events and leads to endothelial overexpression of vascular adhesion molecules (VCAM-1, P-selectin and E-selectin), release of pro-inflammatory cytokines (TNF-α and IL-6) and nitric oxide (NO), release and activation of matrix metalloproteinases (MMP-2 and MMP-9), monocytic maturation into macrophages, and adhesion to the vascular endothelium. Furthermore, TS altered the normal glucose metabolic behaviour ofin vitroBBB capillaries and caused a period of transient anaerobic respiration to meet the cellular bioenergetic demand. Pre-treatment with antioxidant vitamins (C and/or E) effectively reduced the pro-inflammatory activity associated with TS, protecting the viability and functions of the BBB.ConclusionOur results have shown that loss of endothelial viability as well as BBB function and integrity caused by TS exposure can be prevented or at least reduced by normal physiologic concentrations of antioxidant vitaminsin vitro.
HIV Surveillance in a Large, Community-Based Study: Results from the Pilot Study of Project Accept (HIV Prevention Trials Network 043)
Authors: Piwowar-Manning Estelle , Fiamma Agnes , Laeyendecker Oliver , Kulich Michal , Donnell Deborah , Szekeres Greg , Robins-Morris Laura , Mullis, Caroline E , Vallari Ana , Hackett John , Mastro Timothy D , Gray Glenda , Richter Linda , Alexandre Michel W , Chariyalertsak Suwat , Chingono, Alfred , Sweat Michael , Coates Thomas , Eshleman Susan H 
Published: September 2011

Abstract

Background
Project Accept is a community randomized, controlled trial to evaluate the efficacy of community mobilization, mobile testing, same-day results, and post-test support for the prevention of HIV infection in Thailand, Tanzania, Zimbabwe, and South Africa. We evaluated the accuracy of in-country HIV rapid testing and determined HIV prevalence in the Project Accept pilot study.

Methods
Two HIV rapid tests were performed in parallel in local laboratories. If the first two rapid tests were discordant (one reactive, one non-reactive), a third HIV rapid test or enzyme immunoassay was performed. Samples were designated HIV NEG if the first two tests were non-reactive, HIV DISC if the first two tests were discordant, and HIV POS if the first two tests were reactive. Samples were re-analyzed in the United States using a panel of laboratory tests.

Results
HIV infection status was correctly determined based on-in country testing for 2,236 (99.5%) of 2,247 participants [7 (0.37%) of 1,907 HIV NEG samples were HIV-positive; 2 (0.63%) of 317 HIV POS samples were HIV-negative; 2 (8.3%) of 24 HIV DISC samples were incorrectly identified as HIV-positive based on the in-country tie-breaker test]. HIV prevalence was: Thailand: 0.6%, Tanzania: 5.0%, Zimbabwe 14.7%, Soweto South Africa: 19.4%, Vulindlela, South Africa: 24.4%, (overall prevalence: 14.4%).

Conclusions
In-country testing based on two HIV rapid tests correctly identified the HIV infection status for 99.5% of study participants; most participants with discordant HIV rapid tests were not infected. HIV prevalence varied considerably across the study sites (range: 0.6% to 24.4%).

Trial Registration
ClinicalTrials.gov registry number NCT00203749.
A review of studies of parent-child communication about sexuality and HIV/AIDS in sub-Saharan Africa
Authors: Bastien S , Kajula LJ , Muhwezi WW 
Published: September 2011

Abstract
Parent-child sexuality communication has been identified as a protective factor for adolescent sexual and reproductive health, including HIV infection. The available literature on this topic in sub-Saharan Africa is increasing; however a systematic review of studies has not been conducted. This article reviews the literature in the area of parental or caregiver and child communication about sexuality and HIV/AIDS in sub-Saharan Africa. A review of peer reviewed literature published between 1980 and April 2011 was conducted. Communication process studies investigating the frequency, content, style, tone of discussions, preferences, as well as associations with and barriers to sexuality communication are reviewed. In addition, studies which examine behavioral associations with parent-child sexuality communication, and intervention studies to improve parent-child sexuality communication are examined. The findings from process studies suggest wide variation in terms of frequency of discussions, with a range of socio-demographic and other factors associated with sexuality communication. Overall, findings demonstrate that discussions tend to be authoritarian and uni-directional, characterized by vague warnings rather than direct, open discussion. Moreover, parents and young people report a number of barriers to open dialogue, including lack of knowledge and skills, as well as cultural norms and taboos. Findings are less clear when it comes to associations between parental communication and adolescent sexual activity and contraception use. However, nascent indications from intervention research suggest positive findings with increases in frequency and comfort of discussions, among other outcomes. Gaps in the research are identified and discussed with implications for future studies.
Emergence of Japanese encephalitis virus genotype V in the Republic of Korea
Authors: Takhampunya Ratree , Kim Heung-Chul , Tippayachai Bousaraporn , Kengluecha Ampornpan , Klein Terry A , Lee Won-Ja , Grieco John , Evans Brian P 
Published: September 2011

Abstract

Background
Japanese encephalitis virus (JEV) genotype V reemerged in Asia (China) in 2009 after a 57-year hiatus from the continent, thereby emphasizing a need to increase regional surveillance efforts. Genotypic characterization was performed on 19 JEV-positive mosquito pools (18 pools of Culex tritaeniorhynchus and 1 pool of Cx. bitaeniorhynchus) from a total of 64 positive pools collected from geographically different locations throughout the Republic of Korea (ROK) during 2008 and 2010.

Findings
Two regions of the JEV genome were sequenced from 19 pools; the envelope gene and the nonstructural protein 5 (NS5)/3'-untranslated region (UTR). Eighteen pools of Culex tritaeniorhynchus and one pool of Cx. bitaeniorhynchus were positive for genotype I and genotype V, respectively. Sequence alignment of the complete E gene from Cx. bitaeniorhynchus showed high amino acid similarity (98.8%) to the Muar strain, characterized as the first report of genotype V, isolated from an encephalitis patient in Malaysia in 1952.

Conclusion
This study represents the first report of JEV genotype V in the ROK. The reemergence of genotype V in Asia (China and ROK) after more than a half-century and its discovery in Cx. bitaeniorhynchus, a mosquito species previously unknown to carry JEV in the ROK, emphasizes the need for enhanced JE surveillance to monitor the dynamics of JEV strains within the region. Future findings may have implications with regard to JEV vaccination/prevention strategies.
Effects of copper nanoparticle exposure on host defense in a murine pulmonary infection model
Authors: Kim Jong Sung , Adamcakova-Dodd Andrea , O'Shaughnessy Patrick T , Grassian Vicki H , Thorne Peter S 
Published: September 2011

Abstract

Background
Human exposure to nanoparticles (NPs) and environmental bacteria can occur simultaneously. NPs induce inflammatory responses and oxidative stress but may also have immune-suppressive effects, impairing macrophage function and altering epithelial barrier functions. The purpose of this study was to assess the potential pulmonary effects of inhalation and instillation exposure to copper (Cu) NPs using a model of lung inflammation and host defense.

Methods
We used Klebsiella pneumoniae (K.p.) in a murine lung infection model to determine if pulmonary bacterial clearance is enhanced or impaired by Cu NP exposure. Two different exposure modes were tested: sub-acute inhalation (4 hr/day, 5 d/week for 2 weeks, 3.5 mg/m3) and intratracheal instillation (24 hr post-exposure, 3, 35, and 100 μg/mouse). Pulmonary responses were evaluated by lung histopathology plus measurement of differential cell counts, total protein, lactate dehydrogenase (LDH) activity, and inflammatory cytokines in bronchoalveolar lavage (BAL) fluid.

Results
Cu NP exposure induced inflammatory responses with increased recruitment of total cells and neutrophils to the lungs as well as increased total protein and LDH activity in BAL fluid. Both inhalation and instillation exposure to Cu NPs significantly decreased the pulmonary clearance of K.p.-exposed mice measured 24 hr after bacterial infection following Cu NP exposure versus sham-exposed mice also challenged with K.p (1.4 × 105 bacteria/mouse).

Conclusions
Cu NP exposure impaired host defense against bacterial lung infections and induced a dose-dependent decrease in bacterial clearance in which even our lowest dose demonstrated significantly lower clearance than observed in sham-exposed mice. Thus, exposure to Cu NPs may increase the risk of pulmonary infection.
Variable-angle total internal reflection fluorescence microscopy of intact cells of Arabidopsis thaliana
Authors: Wan Yinglang , Ash William M , Fan Lusheng , Hao Huaiqin , Kim Myung K , Lin Jinxing 
Published: September 2011

Abstract

Background
Total internal reflection fluorescence microscopy (TIRFM) is a powerful tool for observing fluorescently labeled molecules on the plasma membrane surface of animal cells. However, the utility of TIRFM in plant cell studies has been limited by the fact that plants have cell walls, thick peripheral layers surrounding the plasma membrane. Recently, a new technique known as variable-angle epifluorescence microscopy (VAEM) was developed to circumvent this problem. However, the lack of a detailed analysis of the optical principles underlying VAEM has limited its applications in plant-cell biology.

Results
Here, we present theoretical and experimental evidence supporting the use of variable-angle TIRFM in observations of intact plant cells. We show that when total internal reflection occurs at the cell wall/cytosol interface with an appropriate angle of incidence, an evanescent wave field of constant depth is produced inside the cytosol. Results of experimental TIRFM observations of the dynamic behaviors of phototropin 1 (a membrane receptor protein) and clathrin light chain (a vesicle coat protein) support our theoretical analysis.

Conclusions
These findings demonstrate that variable-angle TIRFM is appropriate for quantitative live imaging of cells in intact tissues of Arabidopsis thaliana.
The calcar screw in angular stable plate fixation of proximal humeral fractures - a case study
Authors: Osterhoff Georg , Ossendorf Christian , Wanner Guido A , Simmen Hans-Peter , Werner Clément M 
Published: September 2011

AbstractBackgroundWith new minimally-invasive approaches for angular stable plate fixation of proximal humeral fractures, the need for the placement of oblique inferomedial screws ('calcar screw') has increasingly been discussed. The purpose of this study was to investigate the influence of calcar screws on secondary loss of reduction and on the occurrence of complications.MethodsPatients with a proximal humeral fracture who underwent angular stable plate fixation between 01/2007 and 07/2009 were included. On AP views of the shoulder, the difference in height between humeral head and the proximal end of the plate were determined postoperatively and at follow-up. Additionally, the occurrence of complications was documented. Patients with calcar screws were assigned to group C+, patients without to group C-.ResultsFollow-up was possible in 60 patients (C+ 6.7 ± 5.6 M/C- 5.0 ± 2.8 M). Humeral head necrosis occurred in 6 (C+, 15.4%) and 3 (C-, 14.3%) cases. Cut-out of the proximal screws was observed in 3 (C+, 7.7%) and 1 (C-, 4.8%) cases. In each group, 1 patient showed delayed union. Implant failure or lesions of the axillary nerve were not observed. In 44 patients, true AP and Neer views were available to measure the head-plate distance. There was a significant loss of reduction in group C- (2.56 ± 2.65 mm) compared to C+ (0.77 ± 1.44 mm; p = 0.01).ConclusionsThe placement of calcar screws in the angular stable plate fixation of proximal humeral fractures is associated with less secondary loss of reduction by providing inferomedial support. An increased risk for complications could not be shown.