bluuebunny/crossref_metadata_2025 huggingface dataset:
Human leukocyte antigen‐DR expression on peripheral blood monocytes and the risk of pneumonia in pediatric lung transplant recipients
Authors: Hoffman J.A. , Weinberg K.I. , Azen C.G. , Horn M.V. , Dukes L. , Starnes V. A. , Woo M.S.
Published: March 2005

Abstract: Background.Pneumonia is the leading cause of morbidity and mortality after living lobar lung transplantation (LT). Low levels of human leukocyte antigen‐DR (HLA‐DR) expression on peripheral blood monocytes, have been demonstrated to correlate with risk of infection in surgical, trauma, and adult transplant patients. In addition, interleukin (IL)‐10 has been shown to be a negative regulator of HLA‐DR expression. This study investigates whether HLA‐DR expression and serum IL‐10 levels correlate with the development of pneumonia after pediatric LT.

Methods.Thirteen LT recipients were prospectively monitored with blood samples obtained pre‐LT (baseline) and post‐LT weeks 1–4. Mean fluorescence intensity (MFI) of HLA‐DR on CD14+ monocytes was measured by flow cytometry. IL‐10 levels were determined by ELISA from frozen serum collected at the same time points as monocyte HLA‐DR expression. Correlates of pneumonia were abstracted from the medical record.

Results.Monocyte HLA‐DR expression declined in 11 of 13 patients in the first week post‐LT. Two patients without an initial decline and four others whose HLA‐DR expression recovered by week 2 post‐LT, did not develop pneumonia or other infection or rejection. Pneumonia was observed in seven patients, six of whom failed to recover their monocyte HLA‐DR expression by 2 weeks post‐LT. Six of seven patients with pneumonia recovered, and one patient died of aspergillosis. During weeks 1–4, a statistically significant difference was seen in the profile of mean monocyte HLA‐DR expression levels, analyzed as percent of baseline, between the patients with and without pneumonia (P=0.002). The greatest difference between groups over time was seen from post‐LT weeks 1–2 (P=0.003). In addition, when comparing the values at each week, a significant difference was seen between the two groups at post‐LT week 2 (P=0.006) and week 4 (P=0.05). Analysis of IL‐10 concentrations revealed that the overall difference between the groups (patients with and without pneumonia) was statistically significant (P=0.014), with a paradoxical positive correlation between HLA‐DR expression at post‐LT week 4 and IL‐10 concentrations.

Conclusions.Persistent low monocyte HLA‐DR expression was associated with the risk of post‐LT pneumonia in these patients. This measurement may be useful for monitoring risk of infection and stratifying patients into higher and lower risk groups. Increased IL‐10 levels may be protective for infection in this group of patients. At present it is unknown whether the predictive power of HLA‐DR expression is indicative of a global defect in monocytic function or a specific abnormality.
Mycobacterium xenopi pulmonary infection in two renal transplant recipients under sirolimus therapy
Authors: Thaunat O. , Morelon E. , Stern M. , Buffet P. , Offredo C. , Mamzer‐Bruneel M.‐F. , Kreis H.
Published: March 2005

Abstract: Opportunistic infection is a major threat to immunocompromised patients. However, infection due to Mycobacterium xenopi is rare in renal transplant recipients. We report two new cases of M. xenopi pulmonary infection (one case of interstitial pneumopathy and one of a pulmonary nodule) in renal transplant recipients, detected in the same center at an interval of a few months. Both patients were on an immunosuppressive regimen including a recent switch to sirolimus. Sirolimus is a new immunosuppressive drug already known to be responsible for interstitial pneumonitis. It also inhibits interleukin‐12‐induced proliferation of activated T lymphocytes, which is critical for the development of the cell‐mediated immunity that protects against mycobacteria. These two case reports suggest that sirolimus therapy may lead to an impairment of the immune response against intracellular pathogens such as M. xenopi.
Gender differences in bipolar disorder: age of onset, course, comorbidity, and symptom presentation
Authors: Kawa Izabela , Carter Janet D , Joyce Peter R , Doughty Caroline J , Frampton Chris M , Elisabeth Wells J , Walsh Anne ES , Olds Robin J
Published: March 2005

Objective:  To determine whether men and women with bipolar disorder differ in age of onset, course of illness, number of suicide attempts, comorbidity rates and symptom presentation.

Method:  Data were collected from 211 (121 women; 90 men) adults using the Diagnostic Interview for Genetic Studies, medical records, and additional information gathered from relatives.

Results:  Most gender comparisons showed no evidence of differences. Nonetheless, more men than women reported mania at the onset of bipolar I disorder. Men also had higher rates of comorbid alcohol abuse/dependence, cannabis abuse/dependence, pathological gambling and conduct disorder. Men were more likely to report ‘behavioural problems’ and ‘being unable to hold a conversation’ during mania. Women reported higher rates of comorbid eating disorders, and weight change, appetite change and middle insomnia during depression.

Conclusions:  Men and women were generally similar in their symptom presentation, age of onset of bipolar disorder, and in the total number of mood episodes. However, they differed in the type of episode at onset and comorbidity patterns.
Decoding, knowledge, and strategies in comprehension of expository text
Authors: SAMUELSTUEN MARIT S. , BRÅTEN IVAR
Published: March 2005

We examined the relative contribution of decoding, topic knowledge, and strategic processing to the comprehension of social science text in a sample of Norwegian junior high school students. Additionally, we examined the interaction of topic knowledge with strategic processing on students’ text comprehension, and whether poor word‐level skill could be effectively compensated for by higher‐level processing involving knowledge or strategies. Multiple regression analysis indicated that students’ prior knowledge about the topic of the text contributed most to their comprehension. Students’ reported use of organization and monitoring strategies contributed less but still significantly to text comprehension, as did their word decoding skills. However, no interaction between topic knowledge and strategic processing was found. Analyses of variance and post‐hoc comparison tests, supplemented by a descriptive analysis, suggested that the coexistence of poor decoding skill and good text comprehension may be related to much topic knowledge, good strategy use, or both.
Evaluation of the school‐based smoking‐prevention program “BE smokeFREE”
Authors: JØSENDAL OLA , AARØ LEIF EDVARD , TORSHEIM TORBJØRN , RASBASH JON
Published: March 2005

This article examines the impact of the school‐based smoking‐prevention program “BE smokeFREE” on adolescent smoking. A national representative sample of 99 schools (195 classes, 4,441 students) was used when the intervention started in November 1994. Schools were allocated to one of four groups: a comparison group (A) and three intervention groups (B, C, and D). Group B received the most comprehensive intervention. A baseline (autumn 1994) and three follow‐up data collections (1995, 1996, and 1997) were conducted. There were no significant differences in smoking habits among the four groups at baseline. The smoking habits in the group that was involved in the most comprehensive intervention (group B) changed more favourably than those of students in the comparison schools over the three follow‐up data collections. At the third follow‐up, the proportion of students smoking weekly or more in the comparison group was 29.2%, compared with 19.6% in the model intervention group. The two less comprehensive interventions (no teacher in‐service courses in group C, and no involvement of parents in group D) appeared to be less effective than the model intervention. Multilevel multiple logistic regression analyses, comparing changes in smoking habits between students in group B with those among students in the comparison schools, confirm the conclusion that the comprehensive intervention was the most effective. This school‐based intervention, based on a social influence approach, proved to be effective at reducing smoking rates among participants.
Posterior model probabilities via path‐based pairwise priors
Authors: Berger James O. , Molina German
Published: March 2005

We focus on Bayesian model selection for the variable selection problem in large model spaces. The challenge is to search the huge model space adequately, while accurately approximating model posterior probabilities for the visited models. The issue of choice of prior distributions for the visited models is also important.
Accept–reject Metropolis–Hastings sampling and marginal likelihood estimation
Authors: Chib Siddhartha , Jeliazkov Ivan
Published: March 2005

We describe a method for estimating the marginal likelihood, based onChib(1995)andChibandJeliazkov(2001), when simulation from the posterior distribution of the model parameters is by the accept–reject Metropolis–Hastings (ARMH) algorithm. The method is developed for one‐block and multiple‐block ARMH algorithms and does not require the (typically) unknown normalizing constant of the proposal density. The problem of calculating the numerical standard error of the estimates is also considered and a procedure based on batch means is developed. Two examples, dealing with a multinomial logit model and a Gaussian regression model with non‐conjugate priors, are provided to illustrate the efficiency and applicability of the method.
Bayesian model selection using encompassing priors
Authors: Klugkist Irene , Kato Bernet , Hoijtink Herbert
Published: March 2005

This paper deals with Bayesian selection of models that can be specified using inequality constraints among the model parameters. The concept of encompassing priors is introduced, that is, a prior distribution for an unconstrained model from which the prior distributions of the constrained models can be derived. It is shown that the Bayes factor for the encompassing and a constrained model has a very nice interpretation: it is the ratio of the proportion of the prior and posterior distribution of the encompassing model in agreement with the constrained model. It is also shown that, for a specific class of models, selection based on encompassing priors will render a virtually objective selection procedure. The paper concludes with three illustrative examples: an analysis of variance with ordered means; a contingency table analysis with ordered odds‐ratios; and a multilevel model with ordered slopes.
Posterior predictive p‐values for classical null hypotheses
Authors: Maris Gunter
Published: March 2005

We show that for the purpose of testing a classical null hypothesis the posterior predictive check of Rubin (1984) may be inadequate. This inadequacy is caused by the estimation of the nuisance parameters under the null hypothesis. We show that this problem can be solved if the parameters are estimated under the encompassing model.
Using GIS in Areawide Pest Management: A Case Study in South Dakota
Authors: Beckler Amber A. , Wade French B. , Chandler Laurence D.
Published: March 2005

Infestations of corn rootworms (Coleoptera: Chrysomelidae) create economic and environmental concerns in the Corn Belt region of the United States. To supplement the population control tactics of areawide pest management programs, we believe that a better understanding of the spatial relationships between biotic and abiotic or physical factors at the landscape scale is needed. Our research used several geographical information systems (GIS) and spatial analytical techniques to examine relationships between corn rootworm metapopulation dynamics, soil texture, and elevation. Within GIS, several spatially explicit procedures were used that include an interpolation technique, spatial autocorrelation analysis, and contingency analysis. Corn rootworm metapopulation distributions were found to be aggregated and related to soil texture and elevation. We review techniques and discuss our preferences for using particular spatially explicit procedures. The information derived from the spatial analyses demonstrates how GIS can be used in areawide pest management to provide inputs for spatially explicit models to predict future pest populations and formulate more well‐informed pest management decisions. The techniques described in this paper could easily be extended to study the spatial dynamics between other pest populations in agricultural landscapes.
A Comparison Between Contour Elevation Data Sources for DEM Creation and Soil Carbon Prediction, Coshocton, Ohio
Authors: Venteris Erik R. , Slater Brian K.
Published: March 2005

A raster and vector GIS was created for the North Appalachian Experimental Watershed (NAEW) from legacy (1960) 1:2,400‐scale contour maps. The intent of the study was to use terrain data for the spatial modeling of soil organic carbon. It was hypothesized that DEMs derived from these data would be more accurate and therefore more useful for terrain‐based soil modeling than those from USGS 1:24,000‐scale contour data. Central tasks for this study were to digitally capture the 1:2,400‐scale maps, convert digital contour data sources to raster DEMs at multiple resolutions, and derive terrain attributes. A flexible approach was adopted, using software outside of mainstream GIS sources where scientifically or practically advantageous. Elevation contours and streamlines were converted to raster DEMs using ANUDEM. DEMs ranging in resolution from 0.5–30 m were tested for accuracy against precision carrier‐phase GPS data. The residual standard deviation was 1.68 meters for the USGS DEM and 0.36 meters for the NAEW DEM. The optimal horizontal resolution for the NAEW DEM was 5 m and for the USGS 10 m. Five and 10 m resolution DEMs from both data sources were tested for carbon prediction. Multiple terrain parameters were derived as proxies for surficial processes. Soil samples (n = 184) were collected on four zero‐order watersheds (conventional tillage, no‐till, hay and pasture). Multiple least squares regressions (m.l.s.) were used to predict mass C (kg m−2, 30 cm depth) from topographic information. Model residuals were not spatially autocorrelated. Statistically significant topographic parameters were attained most consistently from the 5 m NAEW DEM. However, topography was not a strong predictor of carbon for these watersheds, with r2 ranging from 0.23 to 0.58.
Assessing Similarity of Geographic Processes and Events
Authors: McIntosh John , Yuan May
Published: March 2005

The increased availability of spatiotemporal data collected from satellite imagery and other remote sensors provides opportunities for enhanced analysis of geographic phenomena. Much of the new data includes regular snapshots of the environment. Comparison of these snapshots can provide information about changes to the phenomena of interest. However, conventional GIS data models and analytical tools lack capabilities to adequately handle massive multidimensional data. One of the fundamental tools necessary to meet such challenges is query support to retrieve and summarize data according to dynamic geographic phenomena, such as geographic events and processes, of interest. Such query support depends upon abilities to assess spatiotemporal similarity so that data representing geographic events that exhibit the spatiotemporal characteristics of interest can be identified in a GIS database. To this end, this paper introduces a method to assess similarity of geographic events and processes (such as storms) based on their spatiotemporal characteristics (such as distribution of precipitation). We developed six indices to capture static and dynamic characteristics of geographic events and applied the Dynamic Time Warping method to temporal sequences of the six indices to examine the similarity among these events. With a case study, we demonstrated the proposed indices and method capable of comparing spatiotemporal characteristics of events as recorded in a GIS database and categorizing spatiotemporal data into groups of events according to their behavior in space and time.
Motivating Management: Corporate Compliance in Environmental Protection*
Authors: GUNNINGHAM NEIL A. , THORNTON DOROTHY , KAGAN ROBERT A.
Published: March 2005

Based on interviews with facility managers in the electroplating and chemical industries, this study examines regulated firms’ perceptions of how various instrumental, normative, and social factors motivated their firms’ environmental actions. We found that “implicit general deterrence” (the overall effect of sustained inspection and enforcement activity) was far more important than either specific or general deterrence, and that deterrence in any form was of far greater concern to small and medium‐sized enterprises than it was to large ones. Most reputation‐sensitive firms in the environmentally sensitive chemical industry chose to go substantially beyond compliance for reasons that related to risk management and to the perceived need to protect their social license to operate. Almost half our respondents also provided normative explanations for why they complied. Overall, we conclude that there are various, often interwoven, strands that must be taken into account in understanding what motivates corporate environmental behavior, and how they play out depends very much on the size and sophistication of companies themselves and on the characteristics of the industry sector within which they are located.
Regulation as the Mother of Innovation: The Case of SO2 Control*
Authors: TAYLOR MARGARET R. , RUBIN EDWARD S. , HOUNSHELL DAVID A.
Published: March 2005

This paper explores the relationship between government actions and innovation in an environmental control technology—sulfur dioxide (SO2) control technologies for power plants—through the use of complementary research methods. Its findings include the importance of regulation and the anticipation of regulation in stimulating invention; the greater role of regulation, as opposed to public R&D expenditures, in inducing invention; the importance of regulatory stringency in determining technical pathways and stimulating collaboration; and the importance of regulatory‐driven technological diffusion in contributing to operating experience and post‐adoption innovation in cost and performance. A number of policy implications are drawn from this work.
PSYCHOSOCIAL FACTORS IN PATIENTS WITH CHRONIC KIDNEY DISEASE: The Impact of Social Support on End‐Stage Renal Disease
Authors: Patel Samir S. , Peterson Rolf A. , Kimmel Paul L.
Published: March 2005

Social support is a concept recognizing patients exist to varying degrees in networks through which they can receive and give aid, and in which they engage in interactions. Social support can be obtained from family, friends, coworkers, spiritual advisors, health care personnel, or members of one's community or neighborhood. Several studies have demonstrated that social support is associated with improved outcomes and improved survival in several chronic illnesses, including cancer and end‐stage renal disease (ESRD). The mechanism by which social support exerts its salutary effects are unknown, but practical aid in achieving compliance, better access to health care, improved psychosocial and nutritional status and immune function, and decreased levels of stress may all play key roles. Few data exist regarding social support in patients with ESRD and chronic renal insufficiency, but links between social support and depressive affect and quality of life have been established. Interventions that enhance social support in ESRD patients should be evaluated.
Long‐Term (2‐Year) Clinical Events Following Transthoracic Intramyocardial Gene Transfer of VEGF‐2 in No‐Option Patients
Authors: REILLY JOHN P. , GRISE MARK A. , FORTUIN F. DAVID , VALE PETER R. , SCHAER GARY L. , LOPEZ JOHN , VAN CAMP JOSEPH R. , HENRY TIMOTHY , RICHENBACHER WAYNE E. , LOSORDO DOUGLAS W. , SCHATZ RICHARD A. , ISNER JEFFREY M.
Published: March 2005

Background: The short‐term clinical impact of intramyocardial gene transfer (GT) of the angiogenic protein vascular endothelial growth factor‐2 (VEGF‐2) has been previously reported to significantly reduce Canadian Cardiovascular Society (CCS) angina class and to prolong exercise treadmill test (ETT) time. We describe the safety and long‐term events (>1 year) in consecutive, nonrandomized, patients who received intramyocardial VEGF‐2.

Methods: Thirty patients with intractable CCS class III or IV angina and no options for revascularization underwent direct intramyocardial GT of VEGF‐2 naked DNA via limited thoracotomy at total doses of 0.2, 0.8, or 2.0 mg. Patients were followed for clinical events after 1 year by hospital records, follow‐up visits or telephone contact. Due to one perioperative death, 29 patients were followed.

Results: At a mean follow‐up of 751 ± 102.5 days (range 459–959) there were four deaths (13.8%), five myocardial infarctions (MIs) (17.2%), and seven revascularization procedures (24.1%). There were 15 hospitalizations in 12 patients. At the end of the follow‐up period no patient (0%) had CCS class IV angina, 3 patients (11.5%) had class III angina, and 23 (88.5%) had class I to II angina. There were two new diagnoses of cancer.

Conclusion: Transthoracic intramyocardial injection of VEGF‐2 is associated with an improvement of symptoms of angina in the majority of patients beyond the first year of treatment. Major clinical events such as death, MI, and repeat revascularization are uncommon during the first year but more frequent after 1 year at a rate consistent with the severity of underlying disease in this population with advanced atherosclerosis. The majority of events were the result of progression of disease in areas of the heart remote from the site of GT. A large randomized trial is planned to determine the efficacy of intramyocardial VEGF‐2 injections in inoperable patients.
Review of Subacute Stent Thrombosis Following Percutaneous Coronary Intervention at a Low‐Volume Catheterization Laboratory
Authors: JONES SAMUEL O. , ECKART ROBERT E. , SHRY ERIC A. , SIMPSON DANIEL E.
Published: March 2005

Background: The frequency of coronary stent subacute thrombosis (SAT) following percutaneous coronary intervention (PCI) with uncoated stents in recent studies is 0.5%–0.9%. Prior studies have indicated that complication rates are significantly higher when performed in low‐volume centers. We sought to determine the incidence and outcomes of SAT following PCI with stent placement at a low‐volume catheterization laboratory.

Methods: We reviewed the Brooke Army Medical Center Interventional Database for all consecutive PCIs with stent implantation performed from January 1998 to December 2002. Clinical outcomes were obtained primarily through hospitalization records and clinic follow‐up visits.

Results: There were 789 interventions with stenting on 750 patients over the specified time period, for an average of 158 procedures on 150 patients per year. There were seven cases of SAT, representing a rate of 0.89%. There was no difference in the clinical characteristics, procedural technique, or postprocedural antithrombotic therapy of the subjects with and without SAT. Of those with SAT, there were no subjects requiring surgical revascularization during index hospitalization, and all survived to index hospital discharge. Six of these seven subjects with SAT (85.7%) were alive at one year, with the single death noncardiovascular related.

Conclusions: The incidence of thrombosis occurring within 30 days of intracoronary stent implantation is similar in low‐ and high‐volume catheterization laboratories. In our low‐volume laboratory experience, these events were not associated with significantly increased adverse outcomes.
Fabrication of Highly Porous Mullite Materials
Authors: Barea Rafael , Osendi Maria I. , Miranzo Pilar , Ferreira José M. F.
Published: March 2005

Porous mullite, formed by large spherical‐shaped pores evenly distributed within a mullite matrix, was processed by a direct consolidation method based on the starch swelling properties. Materials with porosities up to 60 vol% and with an average pore size of ∼30 μm were prepared. Porosity matched the starch volume fraction for contents ≥45 vol%, while for lower contents the porosity was above the volume fraction of starch. Formation of crack like defects either surrounding or connecting pores occurred during the drying–sintering processes in the high starch content mullite.
Dispersion Properties of BaTiO3 Colloids with Amphoteric Polyelectrolytes
Authors: Hsu Kung‐Chung , Ying Kuo‐Liang , Chen Lung‐Pin , Yu Bang‐Ying , Wei Wen‐Cheng J.
Published: March 2005

An amphoteric water‐soluble copolymer, i.e., poly(acrylamide/(α‐N,N‐dimethyl‐N‐acryloyloxyethyl) ammonium ethanate) (PAAM/DAAE), was evaluated as a novel dispersant for aqueous BaTiO3 (BT) slurries. The dispersing property of this copolymer was examined by means of rheology, sedimentation, particle size, green density, zeta potential, and leached Ba2+ concentration measurements. The results indicate that PAAM/DAAE could reduce the viscosity of slurries greatly, cause BT particle sizes to shift to smaller values, and make green compacts more consolidated. Compared with a commercial dispersant, ammonium salt of poly(methacrylic acid) (PMAA‐NH4), it is as effective or even better in preparing stabilized suspensions. More importantly, PAAM/DAAE could lessen the leached Ba2+ concentration. This is related to the adsorption behavior of this copolymer onto BT particles, and the interaction between the adsorbed dispersant and dissolved barium ions.
The Crystal Structure of Tobermorite 14 Å (Plombierite), a C–S–H Phase
Authors: Bonaccorsi Elena , Merlino Stefano , Kampf Anthony R.
Published: March 2005

The crystal structure of tobermorite 14 Å (plombierite) was solved by means of the application of the order–disorder (OD) theory and was refined through synchrotron radiation diffraction data. Two polytypes were detected within one very small crystal from Crestmore, together with possibly disordered sequences of layers, giving diffuse streaks along c*. Only one of the two polytypes could be refined: it has B11b space group symmetry and cell parameters a=6.735(2) Å, b=7.425(2) Å, c=27.987(5) Å, γ=123.25(1)°. The refinement converged to R=0.152 for 1291 reflections with Fo>4σ(Fo). The characteristic reflections of the other polytype, F2dd space group, a≈11.2 Å, b≈7.3 Å, c≈56 Å, were recognized but they were too weak and diffuse to be used in a structure refinement. The structure of tobermorite 14 Å is built up of complex layers, formed by sheets of sevenfold coordinated calcium cations, flanked on both sides by wollastonite‐like chains. The space between two complex layers contains additional calcium cations and H2O molecules; their distribution, as well as the system of hydrogen bonds, are presented and discussed. The crystal chemical formula indicated by the structural results is Ca5Si6O16(OH)2·7H2O.
Two‐Fold Diffusion Kinetics of Oxygen Re‐Equilibration in Donor‐Doped BaTiO3
Authors: Yoo Han‐Ill , Lee Chung‐Eun
Published: March 2005

Oxygen (nonstoichiometry) re‐equilibration kinetics was examined, via a conductivity relaxation method, on 1 m/o donor (La)‐doped BaTiO3 (nominal composition, Ba0.99La0.01Ti0.9975O3) against oxygen partial pressure in the range of −16<log (PO2/ atm)≤ 0 at 1200°C. The kinetics has been found to be onefold with a single relaxation time or twofold with two different relaxation times depending on oxygen activity. It is attributed to the relative contributions depending on oxygen activity of fast relaxation of the oxygen sublattice and sluggish relaxation of the cation sublattices: their revelations are determined by the ratio of oxygen vacancy to cation vacancy (say, ) concentrations and their relaxation times. Their chemical diffusion coefficients have been extracted from the relaxation times asanddepending on oxygen activity, which are in good agreement with the reported values. Defect diffusivities are subsequently determined by using the thermodynamic factors of component O and Ti, which have been evaluated from the equilibrium conductivity isotherm, asand.
Reaction Sintering of AlMg–MgO for the Production of MgAl2O4‐Spinel‐Based Composite Ceramics
Authors: Kuntz Meinhard , Dierkes Stephan , Grathwohl Georg
Published: March 2005

Reaction sintering is presented as a new process to produce AlMg spinel‐based ceramics. High oxidation yields of the metallic precursor and full homogenization to single‐phase MgAl2O4‐ceramics are achieved. Five process stages are distinguished and characterized with particular emphasis on the wetting stage of molten alloy on MgO. If the onset of wetting is efficiently controlled extremely high oxidation rates and full oxidation yields near 100% are reached at moderate temperatures up to 1000°C. The resulting microstructure is generated without any ongoing shrinkage and it can be characterized by its closed porosity, which suggests the production of gastight porous fittings and components.
Current Oscillation of Piezoelectric–Ceramic Vibrators Driven by a Constant High Electric Field
Authors: Xu C. H. , Woo C. H. , Shi S. Q. , Chan H. L. W.
Published: March 2005

Current oscillation will occur when a piezoelectric ceramic vibrator is driven by a high electric field. The mechanism of current oscillation is discussed, based on the results of the present experiment. Ring‐shaped lead zirconate titanate (PZT) piezoelectric vibrators are driven by a 5.65 V electric field with a fixed frequency of slightly less than resonance, to form an oscillating current. The sample current, temperature, and phase between the driven electric field and sample current are recorded. The resonance frequency of PZT rings shifts in the direction of low frequency under a high electric field due to the heat produced by dissipated power, and then shifts back due to the effects of aging, which results in current oscillation. The oscillation phenomenon is explained according to the production of strong internal stresses due to abrupt change in temperature, and then, aging process through the rearrangement of domains to relieve various stresses.
Finite Element Implementation of a Thermodynamic Description of Piezoelectric Microstructures
Authors: García R. Edwin , Langer Stephen A. , Carter W. Craig
Published: March 2005

A model and numerical framework is developed for piezoelectric materials. The model treats the piezoelectric and electrostrictive effects by incorporating orientation‐dependent, single‐crystal properties. The method is implemented in Object Oriented Finite Element program, a public domain finite element code, so it can be applied to arbitrary two‐dimensional microstructures with crystallographic anisotropy. The model is validated against analytic solutions. Consistency of the method for known cases permits application of the technique to more complicated two‐dimensional systems. The piezoelectric and electrostrictive response is determined for a few simple device geometries and provides insight for design and convergence criteria.
The Anorthite–Diopside System: Structural and Devitrification Study. Part I: Structural Characterization by Molecular Dynamic Simulations
Authors: Bonamartini Corradi Anna , Bondioli Federica , Cannillo Valeria , Maria Ferrari Anna , Lancellotti Isabella , Montorsi Monia
Published: March 2005

Molecular dynamic simulations of glasses belonging to the anorthite–diopside system have been performed in order to obtain an atomistic description of the material's structure. The structural parameters obtained by the simulations allow to confirm that the glass materials are characterized by a very similar short‐range environment. The main differences have been observed in the intermediate‐range order of the structure that describe the distribution and the packing of the tetrahedra constituting the three‐dimensional networks. It is shown that the glass materials with composition close to the two extremes, corresponding to the pure glass anorthite or pure glass diopside, display the typical structural features of the tectosilicates and inosilicates subclass of minerals, respectively, to which anorthite and diopside crystals belong.
Temperature‐Induced Gelation of Concentrated Sialon Suspensions
Authors: Xu Xin , Ferreira José M. F.
Published: March 2005

A temperature‐induced gelation method has been developed for the preparation of sialon green bodies composed of Si3N4, AlN, Y2O3, and Al2O3. Using a polyester/polyamine condensation polymer as dispersant, stable suspension containing sialon, precursor powders could be prepared in methyl ethyl keton (MEK)/ethanol (E) solvent mixture with solids loading as high as 60 vol%. The solvency of the dispersant in MEK/E decreased dramatically on cooling. The sedimentation tests showed that the settling behavior changed from slow accumulation at ∼20°C to fast deposition of clusters at −15°C, because of the collapse of dispersant chains adsorbed at the surface of the particles. Steady shear viscosity and oscillatory measurements performed for 60 vol% suspensions as functions of temperature and added amounts of dispersant proved that suspensions were of low viscosity and high stability at room temperature, becoming predominantly very highly viscous and elastic as temperature decreased. The gelation mechanism was mainly based on the coiling up of dissolved dispersant molecules, inducing in situ gelation and the formation of a rigid network bridging the suspended particles. The green bodies showed negligible shrinkage during gelation, a small shrinkage during drying, homogeneous microstructures, narrow pore size distributions, and high relative density. It was possible to achieve dense α‐sialon ceramics through pressureless sintering at 1750°C for 2 h.
Methicillin‐resistenter Staphylococcus aureus (MRSA) in chronischen Wunden: Therapeutische Optionen und Perspektiven
Authors: Dissemond Joachim , Körber Andreas , Lehnen Michaela , Grabbe Stephan
Published: March 2005

Es findet sich eine weltweit zunehmende Kontamination chronischer Wunden mit sogenannten Problemkeimen wie dem Methicillin‐resistenten Staphylococcus aureus (MRSA). Auch wenn bislang nicht eindeutig geklärt werden konnte, ob die bakterielle Kontamination einen die Wundheilung prolongierenden Effekt hat, sind die logistischen wie therapeutischen Konsequenzen, die sich aus dem Nachweis von MRSA ergeben sowohl für den Patienten als auch für die behandelnde medizinische Institution erheblich. Insbesondere wenn sich in der Folge eine systemische Infektion manifestieren sollte, stehen für die Therapie von MRSA aktuell lediglich einige wenige Reserveantibiotika zur Verfügung.

Wir möchten in diesem Artikel, neben dem aktuell vorhandenen therapeutischen Standard und verfügbaren Alternativen, insbesondere Perspektiven aufzeigen, die in Zukunft zur Eradikation von MRSA bei Patienten mit chronischen Wunden genutzt werden könnten.

Sollten wir nicht in der Lage sein, neue Therapiestrategien zu entwickeln, die die Resistenzen von Bakterien gegenüber Antibiotika umgehen, werden wir in absehbarer Zukunft bakterielle Infektionen, insbesondere auch bei Patienten mit chronischen Wunden, nicht mehr suffizient behandeln können.
Creating a sense of auditory space
Authors: McAlpine David
Published: March 2005

Determining the location of a sound source requires the use of binaural hearing – information about a sound at the two ears converges onto neurones in the auditory brainstem to create a binaural representation. The main binaural cue used by many mammals to locate a sound source is the interaural time difference, or ITD. For over 50 years a single model has dominated thinking on how ITDs are processed. The Jeffress model consists of an array of coincidence detectors – binaural neurones that respond maximally to simultaneous input from each ear – innervated by a series of delay lines – axons of varying length from the two ears. The purpose of this arrangement is to create a topographic map of ITD, and hence spatial position in the horizontal plane, from the relative timing of a sound at the two ears. This model appears to be realized in the brain of the barn owl, an auditory specialist, and has been assumed to hold for mammals also. Recent investigations, however, indicate that both the means by which neural tuning for preferred ITD, and the coding strategy used by mammals to determine the location of a sound source, may be very different to barn owls and to the model proposed by Jeffress.
Ca2+ permeability of nicotinic acetylcholine receptors from rat dorsal root ganglion neurones
Authors: Fucile Sergio , Sucapane Antonietta , Eusebi Fabrizio
Published: March 2005

Ca2+ entry through neuronal nicotinic ACh receptors (nAChRs) modulates many biological processes in nervous tissue. In order to study the functional role of nAChRs in peripheral sensory signalling, we measured their Ca2+ permeability in rat dorsal root ganglion (DRG) neurones, and analysed the effects of nAChR‐mediated Ca2+ influx on the function of the vanilloid receptor TRPV1. The fractional Ca2+ current (Pf, i.e. the percentage of current carried by Ca2+ ions) flowing through nAChR channels was measured by Ca2+ imaging fluorescence microscopy in combination with the patch‐clamp technique. Functional nAChRs were expressed in a subset of adult DRG neurones (about 24% of the cells), typically with small to medium size as measured by their capacitance (40 ± 3 pF). In most cells, ACh evoked slowly desensitizing currents, insensitive to methyllycaconitine (MLA, 10 nm), a potent antagonist of homomeric nAChRs. Fast decaying currents, probably mediated by α7*‐nAChRs (i.e. native α7‐containing nAChRs), were observed in 15% of ACh‐responsive cells, in which slowly decaying currents, mediated by heteromeric nAChRs, were simultaneously present. The nAChRs of adult DRG neurones exhibited a Pf value of 2.2 ± 0.6% in the presence of MLA and 1.9 ± 0.6% (P > 0.1) in the absence of MLA, indicating that homomeric MLA‐sensitive nAChRs do not contribute to Ca2+ entry into adult DRG neurones. Conversely, 10% of neonatal DRG neurones showed ACh‐evoked currents completely blocked by MLA. In these neurones, nAChRs showed a larger Pf value (9.5 ± 1.5%), indicating the expression of bona fide α7*‐nAChRs. Finally, we report that Ca2+ influx through nAChRs in adult DRG neurones negatively modulated the TRPV1‐mediated responses, representing a possible mechanism underlying the analgesic properties of nicotinic agonists on sensory neurones.
Adaptive Coding of Reward Value by Dopamine Neurons
Authors: Tobler Philippe N. , Fiorillo Christopher D. , Schultz Wolfram
Published: March 2005

It is important for animals to estimate the value of rewards as accurately as possible. Because the number of potential reward values is very large, it is necessary that the brain's limited resources be allocated so as to discriminate better among more likely reward outcomes at the expense of less likely outcomes. We found that midbrain dopamine neurons rapidly adapted to the information provided by reward-predicting stimuli. Responses shifted relative to the expected reward value, and the gain adjusted to the variance of reward value. In this way, dopamine neurons maintained their reward sensitivity over a large range of reward values.
Differential Lysosomal Proteolysis in Antigen-Presenting Cells Determines Antigen Fate
Authors: Delamarre Lélia , Pack Margit , Chang Henry , Mellman Ira , Trombetta E. Sergio
Published: March 2005

Antigen-presenting cells (APCs) internalize antigens and present antigen-derived peptides to T cells. Although APCs have been thought to exhibit a well-developed capacity for lysosomal proteolysis, here we found that they can exhibit two distinct strategies upon antigen encounter. Whereas macrophages contained high levels of lysosomal proteases and rapidly degraded internalized proteins, dendritic cells (DCs) and B lymphocytes were protease-poor, resulting in a limited capacity for lysosomal degradation. Consistent with these findings, DCs in vivo degraded internalized antigens slowly and thus retained antigen in lymphoid organs for extended periods. Limited lysosomal proteolysis also favored antigen presentation. These results help explain why DCs are able to efficiently accumulate, process, and disseminate antigens and microbes systemically for purposes of tolerance and immunity.
High-Resolution Surface-Wave Tomography from Ambient Seismic Noise
Authors: Shapiro Nikolai M. , Campillo Michel , Stehly Laurent , Ritzwoller Michael H.
Published: March 2005

Cross-correlation of 1 month of ambient seismic noise recorded at USArray stations in California yields hundreds of short-period surface-wave group-speed measurements on interstation paths. We used these measurements to construct tomographic images of the principal geological units of California, with low-speed anomalies corresponding to the main sedimentary basins and high-speed anomalies corresponding to the igneous cores of the major mountain ranges. This method can improve the resolution and fidelity of crustal images obtained from surface-wave analyses.
The Magnetic Field of the Large Magellanic Cloud Revealed Through Faraday Rotation
Authors: Gaensler B. M. , Haverkorn M. , Staveley-Smith L. , Dickey J. M. , McClure-Griffiths N. M. , Dickel J. R. , Wolleben M.
Published: March 2005

We have measured the Faraday rotation toward a large sample of polarized radio sources behind the Large Magellanic Cloud (LMC) to determine the structure of this galaxy's magnetic field. The magnetic field of the LMC consists of a coherent axisymmetric spiral of field strength ∼1 microgauss. Strong fluctuations in the magnetic field are also seen on small (<0.5 parsec) and large (∼100 parsecs) scales. The large bursts of recent star formation and supernova activity in the LMC argue against standard dynamo theory, adding to the growing evidence for rapid field amplification in galaxies.
Complement Factor H Polymorphism in Age-Related Macular Degeneration
Authors: Klein Robert J. , Zeiss Caroline , Chew Emily Y. , Tsai Jen-Yue , Sackler Richard S. , Haynes Chad , Henning Alice K. , SanGiovanni John Paul , Mane Shrikant M. , Mayne Susan T. , Bracken Michael B. , Ferris Frederick L. , Ott Jurg , Barnstable Colin , Hoh Josephine
Published: March 2005

Age-related macular degeneration (AMD) is a major cause of blindness in the elderly. We report a genome-wide screen of 96 cases and 50 controls for polymorphisms associated with AMD. Among 116,204 single-nucleotide polymorphisms genotyped, an intronic and common variant in the complement factor H gene (
CFH
) is strongly associated with AMD (nominal
P
value <10
-7
). In individuals homozygous for the risk allele, the likelihood of AMD is increased by a factor of 7.4 (95% confidence interval 2.9 to 19). Resequencing revealed a polymorphism in linkage disequilibrium with the risk allele representing a tyrosine-histidine change at amino acid 402. This polymorphism is in a region of CFH that binds heparin and C-reactive protein. The
CFH
gene is located on chromosome 1 in a region repeatedly linked to AMD in family-based studies.
Complement Factor H Variant Increases the Risk of Age-Related Macular Degeneration
Authors: Haines Jonathan L. , Hauser Michael A. , Schmidt Silke , Scott William K. , Olson Lana M. , Gallins Paul , Spencer Kylee L. , Kwan Shu Ying , Noureddine Maher , Gilbert John R. , Schnetz-Boutaud Nathalie , Agarwal Anita , Postel Eric A. , Pericak-Vance Margaret A.
Published: March 2005

Age-related macular degeneration (AMD) is a leading cause of visual impairment and blindness in the elderly whose etiology remains largely unknown. Previous studies identified chromosome 1q32 as harboring a susceptibility locus for AMD. We used single-nucleotide polymorphisms to interrogate this region and identified a strongly associated haplotype in two independent data sets. DNA resequencing of the complement factor H gene within this haplotype revealed a common coding variant, Y402H, that significantly increases the risk for AMD with odds ratios between 2.45 and 5.57. This common variant likely explains ∼43% of AMD in older adults.
Kinetic Study of Alkaline Hydrolysis of Substituted Phenyl Tosylates. XXII. Variation of Ortho Substituent Effect with Solvent
Authors: Nummert Vilve , Piirsalu Mare , Lepp Marika , Mäemets Vahur , Koppel Ilmar
Published: March 2005

The second-order rate constants k (dm3 mol-1 s-1) for the alkaline hydrolysis of meta-, para-, and ortho-substituted phenyl tosylates 4-CH3C6H4SO2OC6H4-X in aqueous 0.5 M Bu4NBr have been measured spectrophotometrically in a wide temperature range. The log k values for ortho-substituted derivatives at various temperatures together with meta- and para-substituted derivatives were analyzed using the modified Fujita-Nishioka equation log km,p,ortho = c0 + c1(m,p,ortho)σ° + c2(ortho)σI + c3(1/T) + c4(m,p,ortho)(1/T)σ° + c5(ortho)(1/T)σI. In order to study the dependence of substituent effects, especially ortho inductive and resonance terms on different solvent parameters, the following equation was used: ∆log km,p,ortho = c0 + c1(m,p,ortho)σ° + c2(ortho)σI + c3∆E + c4∆Y + c5∆P + c6(m,p,ortho)∆Eσ° + + c7(m,p,ortho)∆Yσ° + c8(m,p,ortho)∆Pσ° + c9(ortho)∆EσI + c10(ortho)∆YσI + c11(ortho)∆PσI. ∆log k = log kX - log kH, σ° and σI, are the Taft polar and inductive substituent constants, E, Y and P, are the solvent electrophilicity, polarity and polarizability parameters, respectively. In data treatment ∆E = ES - EH2O, ∆Y = YS - YH2O, ∆P = PS - PH2O were used. The solvent electrophilicity was found to be the main factor responsible for changes in the ortho, para, and meta polar substituent effects with medium. The variation of the ortho inductive term with the solvent electrophilicity ES was found to be twice smaller than that for para substituents, while the ortho resonance term appeared to vary with solvent nearly similarly to that for para substituents. The ortho effect caused by the supplementary inductive effect from ortho position was found to disappear in a solvent whose electrophilic solvating power is comparable to pure DMSO (E ≈ 4).
Vibration barriers for shock-producing equipment
Authors: Naggar M Hesham El , Chehab Abdul Ghafar
Published: March 2005

Most modern manufacturing facilities have hammers or presses in addition to precision cutting equipment as their production machinery. Foundations supporting hammers and presses experience powerful dynamic effects. These effects may extend to the surroundings and affect labourers, other sensitive machines within the same facility, or neighbouring residential areas. To control vibration problems, wave barriers may be constructed to isolate vibrations propagating to the surroundings. This paper examines the efficiency of both soft and stiff barriers in screening pulse-induced waves for foundations resting on an elastic half-space or a layer of limited thickness underlain by rigid bedrock. The effectiveness of concrete, gas-cushion, and bentonite trenches as wave barriers is examined for different cases of soil layer depth, trench location, and embedment of the foundation. The model was formulated using the finite element method, and the analysis was performed in the time domain. The efficiency of different types of wave barriers in vibration isolation for shock-producing equipment was assessed and some guidelines for their use are outlined.Key words: hammer foundation, impact load, gas-cushion trenches, concrete trenches, soilbentonite trench, finite element modeling.