bluuebunny/crossref_metadata_2025_split huggingface dataset:
IEEE 802.11e/802.11k wireless LAN: spectrum awareness for distributed resource sharing
Authors: Mangold Stefan , Zhong Zhun , Hiertz Guido R. , Walke Bernhard 
Published: November 2004

AbstractCoordinating priorities in wireless medium access is difficult when radio networks operate with contention‐based medium access. Contention‐based medium access protocols such as listen‐before‐talk are widely employed today, and for example used in the popular IEEE 802.11 protocol. Contention‐based protocols are used for wireless communication in unreliable radio environments such as the unlicensed frequency bands with their typically irregular and unpredictable interferences. However, to support time‐bounded traffic with a certain quality of service (QoS) support is extremely difficult, because it requires the knowledge of how aggressive other radio stations, which also contend for radio resources, access the medium. In this contribution, we discuss a new measurement in the IEEE 802.11k draft standard, together with the IEEE 802.11e draft standard for coordinating priorities. By combining the two extensions of IEEE 802.11, we develop an algorithm that allows radio stations to estimate the achievable throughput per radio station (the saturation throughput) in the presence of other radio stations. Our algorithm further allows predicting the saturation throughput per radio station in the presence of other non‐802.11 radio networks, because it only relies on the information about how the medium is used by other stations, i.e. for what duration other stations have to sense the medium as idle before initiating transmissions. The algorithm does not require knowledge about the contention‐parameters (like, e.g. minimum contention window sizes) used by other radio stations, and only relies on medium sensing information. For this reason, we refer to spectrum awareness in this work. We modify an existing model that was originally developed for calculating the saturation throughput in IEEE 802.11, to calculate the saturation throughput for IEEE 802.11e with one single priority. We then describe a new measurement, which is part of the IEEE 802.11k draft standard. The measurement provides information about medium access probabilities of other radio stations per contention window slots. These probabilities provide the information about how aggressive the medium is utilized by other stations. The probabilities are used in our model for approximating the saturation throughput per station and priority in the presence of other radio stations. As a result, with the help of the new model, a radio station is able to estimate its own expected saturation throughput. The comparison of the model with stochastic simulation stations indicates that our model approximates the saturation throughput per station and priority sufficiently in many scenarios, and hence allows to predict expected saturation throughputs per radio station. Copyright © 2004 John Wiley & Sons, Ltd.
Bounds on the effective conductivity of two‐dimensional N‐component isotropic and symmetric cell mixtures
Authors: Chinh Pham Duc 
Published: November 2004

AbstractVariational perturbation approach is applied to derive upper and lower bounds on the effective conductivity of two‐dimensional isotropic quasisymmetric (or symmetric cell) N‐component media, which involve only the definite information about the volume proportions and properties of their components. The bounds appear to improve upon, or coincide (in case of circular cell subclass) with, the bounds constructed by an alternative variational approach. The general geometry‐dependent bounds for isotropic composites converge to yield the exact effective conductivity of the multi‐coated circles model.
Dugdale‐model for a ring‐shaped crack in a transtropic thick walled cylinder
Authors: Uyaner M. 
Published: November 2004

AbstractIn this study, a problem of a ring‐shaped crack contained in an infinitely long thick‐walled cylinder is considered. The problem is formulated for a transtropic (transversely isotropic) material by using integral transform technique under uniform load. The governing elasticity equation for the transtropic axisymmetric problem in cylindrical co‐ordinates was obtained in terms of a Love type stress function. Hankel and Fourier transforms were applied on the stress function because of the geometry of the configuration and boundary conditions. The stress function was expressed in terms of the governing equation. Using the boundary conditions, the problem reduced to a singular integral equation. This singular integral equation is solved by using the Gaussian Quadrature. Then the stress intensity factor at the crack tip was determined. The plastic zone widths are obtained by using the Dugdale model. The plastic zone widths are plotted for various ring‐shaped crack sizes and transtropic materials.
A phenomenological model for hysteresis in polycrystalline shape memory alloys
Authors: Kružík M. , Otto F. 
Published: November 2004

AbstractWe propose a phenomenological model describing stress and temperature induced transformations in polycrystalline shape memory alloys. Polycrystallinity is mimicked on the level of a finite element discretization: Each element is treated as a single grain of a randomly chosen orientation. This heterogeneity destroys the undesirable effect of instantaneous transformation under spatially homogeneous loading or heating. We present various computational experiments on the hysteretic effects.
Inhibition of Leukocyte Adherence Enables Venular Control of Capillary Perfusion in Streptozotocin‐Induced Diabetic Rats
Authors: NELLORE KAVITHA , HARRIS NORMAN R. 
Published: November 2004

ABSTRACTObjective: Vasoactive molecules can diffuse from venules to dilate closely paired arterioles and enhance capillary perfusion. Venular control of capillary flow has been found to be dependent on nitric oxide (NO), which might be scavenged rapidly in diabetic microvasculature due to the presence of activated leukocytes. This study attempts to improve venular control of capillary flow using fucoidan, which inhibits venular leukocyte adhesion.Methods: Microvascular red blood cell velocity was measured in the mesentery of streptozotocin‐induced diabetic rats, with and without fucoidan treatment, and in normal rats. Arteriolar pathways leading to branching capillaries were videotaped to measure the percent of the surrounding area occupied by a venule (% pairing). Microvascular wall NO was measured using fluorescent diaminofluorescein‐2‐diacetate in diabetic rats, with and without fucoidan treatment.Results: In normal rats, close pairing of venules to arterioles resulted in faster capillary flow. However, after 4–5 weeks of diabetes, the correlation between capillary velocity and % pairing was no longer significant. Capillary velocity and % pairing decreased ∼ 50% in comparison to normal rats. Treatment of diabetic rats with fucoidan restored venular control of capillary flow and increased NO levels.Conclusion: Leukocyte‐derived mediators that scavenge NO may lead to inadequate venular control of capillary flow in diabetes.
Arteriolar Responses to Vasodilator Stimuli and Elevated PO2 in Renin Congenic and Dahl Salt‐Sensitive Rats
Authors: DRENJANCEVIC‐PERIC INES , GREENE ANDREW S. , KUNERT MARY PAT , LOMBARD JULIAN H. 
Published: November 2004

ABSTRACTObjectives: Angiotensin II suppression leads to impaired vascular relaxation in normotensive animals on a high‐salt diet. The goal of this study was to determine whether normal vascular reactivity could be restored by transferring the chromosomal region carrying the Dahl salt‐resistant (R) renin gene into the Dahl salt‐sensitive (SS) genetic background in a strain of renin congenic rats (RGRR).Methods: Male RGRR and SS rats were fed low‐salt (0.4%) and high‐salt (4%) diets for 4 weeks. The responses of cremaster muscle arterioles to acetylcholine (ACh), sodium nitroprusside (SNP), and elevated PO2 were assessed using video microscopy.Results: ACh‐induced dilation was significantly enhanced in RGRR on a high‐salt diet compared to SS rats, while dilation to the NO donor SNP was similar in both strains. A high‐salt diet significantly enhanced arteriolar constriction in response to elevated PO2, in both SS and RGRR rats.Conclusions: These data suggest that transfer of the chromosomal region containing the renin gene is crucial in the recovery of ACh‐induced dilation of arterioles in RGRR rats vs. SS rats, and that factors in the SS genetic background contribute to an enhanced sensitivity to elevated PO2, independent of genes on chromosome 13.
Pentastarch in a Balanced Solution Reduces Hepatic Leukocyte Recruitment in Early Sepsis
Authors: ONDIVEERAN HARI KUMAR , FOX‐ROBICHAUD ALISON E. 
Published: November 2004

ABSTRACTObjective: To characterize the hepatic leukocyte endothelial cell interactions occurring in early sepsis and to determine whether this is influenced by fluid treatment.Methods: Sepsis was induced by cecal ligation and perforation in C57Bl/6 mice. One of 6 iv fluid regimes was given immediately postsurgery and at 6 h. The hepatic microcirculation was examined by intravital microscopy at 6 h.Results: All 0.9% saline‐based solutions were associated with an increase in leukocyte–endothelial cell interactions as demonstrated by an increase in the rolling flux in the sham and naïve mice. In the septic mice treated with normal saline, there was a 20‐fold increase in leukocyte adhesion within the postsinusoidal venules, compared to sham mice. Treatment with lactated Ringer's reduced the sepsis‐mediated leukocyte recruitment by 50%. When septic mice received 6% pentastarch in a balanced solution or 3% saline, venular leukocyte adhesion was reduced by an additional 50%. When the pentastarch was prepared in normal saline there was no further reduction in venular leukocyte adhesion compared to the lactated Ringer's‐treated mice. All hyperosmolar solutions improved the sepsis‐induced reduction in sinusoidal perfusion but only the pentastarch in the balance solution significantly reduced the number of adherent leukocytes within the sinusoids.Conclusions: Hepatic leukocyte recruitment occurs early in sepsis. Pentastarch in a balanced solution but not in normal saline significantly reduces hepatic leukocyte recruitment, suggesting solution composition, as well as osmolarity impact the innate immune response.
Antecedent Ethanol Ingestion Prevents Postischemic P‐Selectin Expression in Murine Small Intestine
Authors: DAYTON CATHERINE , YAMAGUCHI TAIJI , KAMADA KAZUHIRO , CARTER PATSY , KORTHUIS RONALD J. 
Published: November 2004

ABSTRACTObjective: Ethanol ingestion 24 h prior to ischemia and reperfusion (I/R) prevents postischemic leukocyte rolling and adhesion in postcapillary venules of the small bowel. Since I/R‐induced leukocyte rolling is critically dependent on the expression of P‐selectin by endothelial cells lining postcapillary venules, the authors hypothesized that antecedent ethanol consumption would attenuate postischemic expression of this adhesive ligand.Methods: To address this postulate, P‐selectin expression was evaluated using a dual radiolabeled monoclonal antibody technique in the jejunum of mice that received either distilled water vehicle or ethanol by gavage (dose) on day 1 and then were subjected to sham I/R (nonischemic controls) or I/R (20 min ischemia/60 min reperfusion) 24 h later.Results: I/R was associated with a 2‐fold increase in P‐selectin expression relative to nonischemic controls, an effect that was largely abolished by antecedent ethanol ingestion. Exposing the bowel to adenosine deaminase or adenosine A2 receptor antagonists (DMPX or ZM241385), an NO synthase inhibitor (L‐NIO) or an NO scavenger (PTIO), or an antioxidant (mercaptoproprionyl glycine) during the period of ethanol exposure on day 1 prevented the beneficial effect of ethanol to limit I/R‐induced P‐selectin expression, on day 2.Conclusions: The data indicate that antecedent ethanol exposure prevents postischemic P‐selectin expression on day 2 by a mechanism that is triggered by adenosine A2 receptor activation and the formation of nitric oxide (NO) and reactive oxygen species (ROS) during the period of ethanol exposure on day 1.
Intratympanic Gentamicin for Menière's Disease: a Meta‐Analysis
Authors: Cohen‐Kerem Raanan , Kisilevsky Vitaly , Einarson Thomas R. , Kozer Eran , Koren Gideon , Rutka John A. 
Published: November 2004

AbstractObjectives: To systematically review the published experience on intratympanic gentamicin treatment for intractable Menière's disease.Study Design: Meta‐analysis using a random effect model.Methods: A comprehensive literature search was performed for articles using intratympanic gentamicin as a sole treatment modality with reporting of results according to the American Academy of Otolaryngology Head and Neck Surgery (AAO‐HNS) guidelines for Menière's disease. Two reviewers independently assessed trial quality and extracted data.Results: Fifteen trials with 627 patients met the inclusion criteria. All trials reported “before‐after” outcome measures, using patients as their own controls. No double‐blind or blinded prospective control trials were identified. Complete (class A) vertigo control was achieved in 74.7% (confidence interval [CI]95% 67.8–81.5%) of patients, and complete or substantial (class B) control was achieved in 92.7% (CI95% 89.5–96.0%). The success rate was not affected by gentamicin treatment regimen (fixed vs. titration). Hearing level and word recognition were not adversely affected, regardless of gentamicin treatment regimen. Analysis of functional level was not performed because of lack of data in the selected articles.Conclusions: Intratympanic gentamicin treatment for intractable Menière's disease appears to be effective in the relief of vertigo. Cochleotoxicity and ototoxicity is unlikely to be a major side effect. However, the level of evidence reflected from the eligible articles is insufficient, especially because of relatively poor study design. Therefore, it is prudent that patients eligible for this type of treatment should be selected carefully and titrated with low‐dose gentamicin. Further investigation with this treatment modality with control subjects is warranted.
Prevalence and Epidemiology of Hepatitis C Virus in Patients with Squamous Cell Carcinoma of the Head and Neck
Authors: Nobles James , Wold Christian , Fazekas‐May Mary , Gilbert Jill , Friedlander Paul L. 
Published: November 2004

AbstractObjective: Recently, we have noticed that a large number of patients with squamous cell carcinoma of the head and neck (SCCHN) are also infected with the hepatitis C virus (HCV). A review of the literature has revealed no published studies examining this association. The objective of this study was to determine the incidence and epidemiology of HCV infection in patients with SCCHN.Study Design: A retrospective chart review.Methods: Patients diagnosed with SCCHN were analyzed to determine whether they were screened for HCV. Patients were then stratified into two groups (HCV positive and HCV negative). The patient's age at onset, site and stage of the tumor at presentation were determined, and statistical analysis was performed.Results: Ninety‐nine (26%) patients were screened, and 21 (21.2%) were HCV positive. This incidence was increased when compared with previously published data (9.9%) (P < .0038). HCV‐positive patients presented at an earlier age (51 years) versus the HCV‐negative group (60 years) (P < .0002). There were no significant differences in the site or stage at presentation.Conclusions: In this study, 21% of patients diagnosed with SCCHN were found to be infected with HCV. These patients presented at an earlier age but had similar presentation with respect to site and stage. More research is needed to determine the significance of HCV infection in this patient population.
Assessment of Gene Expression in Head and Neck Carcinoma Using Laser Capture Microdissection and Real‐Time Reverse Transcription Polymerase Chain Reaction
Authors: Malhotra Pramit S. , Malekfzali Ashi , Bonner Robert F. , Juhn Steven , Van Waes Carter , Chen Zhong 
Published: November 2004

AbstractObjectives: To quantify gene expression in tumor cells from human head and neck squamous cell carcinomas (HNSCC) using laser capture microdissection (LCM).Study Design: Histopathologically identified HNSCC cells were microdissected from frozen sections, RNA was isolated, and vascular endothelial growth factor (VEGF) gene expression was measured by real‐time reverse transcriptase polymerase chain reaction (RT‐PCR).Materials and Methods: Two human HNSCC tumor samples and matched normal mucosal biopsies and five human xenograft tumor specimens were harvested, embedded, and frozen in OCT. The frozen tumors were sectioned to 8 to 10 μm in thickness, and hematoxylin‐eosin (H&E) staining was performed before LCM. An estimated 2,000 to 3,000 tumor cells were microdissected from frozen sections and processed for RNA isolation. mRNA for VEGF was analyzed by real time RT‐PCR (TaqMan) with commercially available primers and probes.Results: Two thousand to 3000 cells were necessary to obtain a suitable quantity of RNA for subsequent gene expression study by real‐time RT‐PCR. The gene expression of VEGF, a major tumor angiogenic factor, was tested in microdissected HNSCC and compared with uninvolved normal mucosal controls. A greater than seven‐fold increase of VEGF expression in tumor specimens versus mucosal controls was observed.Conclusions: LCM is a novel sample conserving technique that allows the precise selection of tumor cells from a heterogeneous architecture. The combination of LCM and real‐time RT‐PCR appears particularly efficacious for studying HNSCC molecular pathogenesis and identifying tissue‐specific biomarkers.
Hearing Loss in Union Army Veterans from 1862 to 1920
Authors: Sewell Ryan K. , Song Chen , Bauman Nancy M. , Smith Richard J. H. , Blanck Peter 
Published: November 2004

AbstractObjectives: To examine the prevalence of hearing loss (HL) in Union Army (UA) veterans by year, birth cohort, and occupation, and to compare Civil War pension and contemporary disability programs by examining monthly dollar awards.Study Design: A retrospective review of medical records for 17,722 UA veteran pension applicants, a subset of some 35,000 soldiers retrieved randomly from the Military Archives.Methods: The diagnosis of HL was based on review of medical records, which used gross measurements because of the unavailability of audiometric testing.Results: One third (5,891 or 33%) of pensioners sampled received compensation for HL. The veterans with HL suffered predominantly from left‐sided HL (4,091 or 70%), which is consistent with noise‐induced HL in a right‐handed individual firing a rifle. Comparison of civilian occupations reveals minimal variation in prevalence of HL. Civil War pensions for unilateral HL averaged $134.04 per year, representing nearly one third of the average annual income in 1890. Bilateral HL received nearly twice that amount. Today, military veterans receive $1,248 annually for unilateral loss and $27,288 annually for bilateral loss. Social Security disability benefits are granted only for bilateral HL, with an average 60‐year‐old individual receiving $11,400 per year.Conclusion: HL was a common disability among UA Civil War veterans, with noise exposure a likely etiology for the HL. The differing levels of compensation for HL may reflect differing perceptions on the incapacitating effects of HL.
Therapeutic Potential of Growth Factors for Aging Voice
Authors: Hirano Shigeru , Bless Diane M. , del Río Alejandro Muñoz , Connor Nadine P. , Ford Charles N. 
Published: November 2004

AbstractObjectives/Hypothesis: It has been reported that in aged vocal folds, dense collagen deposition takes place and hyaluronic acid decreases in the lamina propria, which are thought to contribute to the vocal problems occurring with age (presbyphonia). To restore aged vocal folds to their younger state, it seems crucial to address these age‐related lamina propria changes. Intervention that might increase hyaluronic acid and decrease collagen would appear to be a potentially useful approach. The present study examined the effects of growth factors on aged fibroblasts in terms of the production of hyaluronic acid and collagen type I.Study Design: In vitro study using animal model.Methods: Fibroblasts were harvested from young and aged rat vocal folds and cultured with or without hepatocyte growth factor and/or basic fibroblast growth factor at different concentrations. Subsequently, the production of hyaluronic acid and collagen type I was examined in the supernatant culture media using enzyme‐linked immunosorbent assay.Results: Aged fibroblasts produced less hyaluronic acid than younger fibroblasts. When aged and young fibroblasts were cultured with basic fibroblast growth factor, hyaluronic acid production increased and collagen type I production decreased regardless of the concentration, whereas the effects of hepatocyte growth factor appeared to vary with concentration. The basic fibroblast growth factor also was associated with stimulation of growth of aged fibroblasts.Conclusion: The present results suggest that growth factors, especially basic fibroblast growth factor, may have therapeutic potential in restoration of aged vocal fold.
Vestibular Evoked Myogenic Potentials in Acute Low‐Tone Sensorineural Hearing Loss
Authors: Wu Chin‐Lung , Young Yi‐Ho 
Published: November 2004

AbstractObjective/Hypothesis: It was the authors' premise that the vestibular evoked myogenic potential (VEMP) test may be used to differentiate acute low‐tone hearing loss (ALHL) from Menière's disease with low‐tone HL.Study Design: Prospective study.Methods: From January 2000 to December 2002, consecutive 12 patients with ALHL and another 12 patients with definite Menière's disease with low‐tone HL were enrolled in this study. All patients underwent audiometry and VEMP test, before and after treatment with isosorbide for 3 consecutive months.Results: Before treatment, 12 patients with ALHL revealed normal VEMPs (11, 92%) and augmented VEMPs (1). After treatment, 11 (92%) patients had resolved to normal hearing within 3 days. One year later, two (17%) patients progressed to Menière's disease. In comparison with Menière's disease, 6 (50%) of 12 patients showed normal VEMPs before treatment, and 7 (58%) patients had their hearing improved 3 months after treatment. Comparison of VEMP responses or hearing outcome between both groups exhibited significant differences.Conclusion: Most patients with ALHL reveal normal VEMPs throughout the episode, indicating that the saccule is spared. In contrast, 50% of Menière's disease patients with low‐tone HL demonstrate abnormal VEMPs, showing a significant difference. Therefore, the VEMP test can be used to differentiate ALHL from Menière's disease with low‐tone HL.