bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thermo-hydrodynamic study of the journal bearing under static load
Authors: Ighil N Tala , Bounif A , Maspeyrot P 
Published: September 2008

A number of studies have been carried out on the hydrodynamic lubrication of journal bearings. This article seeks to summarize this work, presenting it in the form of a flow chart. The treatment of rupture and reformation of the film fluid in the contact region, for a steady loaded circular journal bearing, are accomplished using the Reynolds and the Jakobsson—Floberg and Olsson (JFO) boundary conditions. A flow chart taking into account the resolution of some of the hydrodynamic lubrication problems is elaborated. A computer code is carried out for solving the Reynolds equation and for calculating the most important parameters relating to a hydrodynamic contact. The obtained results for a finite-length bearing are compared with those obtained from the short-bearing hypothesis. In addition, a global thermal study is carried out in order to evaluate the effect of temperature.
A regenerative flow compressor as a secondary air pump for engine emission control
Authors: Engeda A , Elkacimi Y 
Published: September 2008

A secondary air pump (SAP) is an air compressor that supplies air to the exhaust system of an automotive engine for the emission control of the engine. The SAP system has been offered as an emission control device in later versions of cars, starting in the mid-1990s. Various types of rotary and positive displacement air pumps have been tested and used for SAP application. The regenerative flow compressor/pump (RFC or RFP) and the centrifugal compressor have been found to be best suited for SAP application. This paper discusses the performance of an RFC for SAP application and shows the RFC to be the best choice for satisfying the required specifications of the SAP. Computational fluid dynamics analysis of the RFC for an SAP application was carried out to study its performance in detail.
Single-blade impeller development using the design of experiments method in combination with numerical simulation
Authors: De Souza B , Niven A , Daly J 
Published: September 2008

This paper concerns the optimization of single-blade impellers as used in the waste-water industry. When considering wastewater pump hydraulics, both the ability to handle solids and hydraulic efficiency become essential criteria for optimization. An innovative approach was taken to this optimization problem through the combination of two separate tools: design of experiments (DOE) and computational fluid dynamics (CFD). Through the use of DOE, it was possible to investigate the effect on hydraulic performance of five key parameters identified as being critical to solids handling. The designed experiment required 32 runs only, as compared with 243 runs (35), which would have been necessary using the traditional ‘trial-and-error’ approach. For each DOE run, unique impeller geometry was created. A transient numerical methodology was adopted for the performance evaluation of each impeller. The methodology was validated and verified on several single-blade impellers covering a range of design specific speed ( Ns=32 to 77). In all benchmark models, excellent agreement with experimental data was observed. The models, resulting from the designed experiment, have advanced the state of the art in terms of single-blade impeller design, quantified relationships between solids handling parameters and led to the development of new higher efficiency single-blade impellers with improved solids handling ability over conventional designs.
Optimization of accelerometers for measuring walking
Authors: Foster R , Lanningham-Foster L , Levine J 
Published: September 2008

The devastating impact of obesity on global health is without question and it is generally agreed that low levels of physical activity, particularly sitting (i.e., sedentariness), are important in its pathogenesis. Therefore, the measure of physical activity such as walking is vital to its use in the research and clinical milieu. This study investigated three accelerometry parameters (sampling rate, range, and data depth) on ten healthy subjects (BMI 18–31 kg/m2) walking on a calibrated treadmill at eight speeds (0, 0.95, 1.74, 2.48, 3.22, 4.04, 4.83, and 5.70 km/h) while wearing a three-axis accelerometer on the thigh (Crossbow Technology, San Jose, CA) in order to find an optimal system for the determination of walking speed, as well as a new data analysis strategy using a differentiation of the acceleration values (jerk). Twenty-four sampling rates (2–25 Hz in 1-Hz intervals) and seven acceleration ranges (± 1  g – ± 2.5  g at 0.25- g intervals) were used to create a 24 × 7 factorial design. Data was also truncated from two to seven digits in the mantissa. This study found that although there is an improvement in walking speed prediction when sampling rate was set above 4 Hz ( P<0.0002), there was no further improvement when the sampling rate is set higher. This study found that there is an increase in walking speed prediction accuracy when the range of acceleration is limited to ± 1  g ( P<0.0024 for ± 2  g versus ± 1  g). This study found that increasing or decreasing data depth has no impact on walking speed prediction accuracy. Further, this study found that a model based on jerk was accurate at predicting walking speeds ( r2 0.9 for all comparisons). For measuring walking using a sensor on the thigh, there is no significant improvement gained by large sampling rates, data ranges, or data precision. A model based on the time rate of change of acceleration is a valid analysis tool for measuring walking.
Queues with Many Servers: The Virtual Waiting-Time Process in the QED Regime
Authors: Mandelbaum Avishai , Momčilović Petar 
Published: September 2008

We consider a first-come first-served multiserver queue in the Quality- and Efficiency-Driven (QED) regime. In this regime, which was first formalized by Halfin and Whitt, the number of servers N is not small, servers' utilization is [Formula: see text] (Efficiency-Driven) while waiting time is [Formula: see text] (Quality-Driven). This is equivalent to having the number of servers N being approximately equal to [Formula: see text], where R is the offered load and β is a positive constant. For the G/DK/N queue in the QED regime, we analyze the virtual waiting time VN(t), as N increases indefinitely. Assuming that the service-time distribution has a finite support (hence the DK in G/DK/N), it is shown that, in the limit, the scaled virtual waiting time [Formula: see text] is representable as a supremum over a random weighted tree (S denotes a service time). Informally, it is then argued that, for large N, [Formula: see text]here [Formula: see text] is the averaging of [Formula: see text] over S, and the process [Formula: see text] is zero-mean Gaussian that summarizes all relevant information about arrivals and service times ([Formula: see text] arises as a limit of an infinite-server (G/DK/∞) process, appropriately scaled). The results are obtained by using both combinatorial and probabilistic arguments. Possible applications of our approximations include fast simulation of queues and estimation/prediction of customer waiting times in the QED regime.
The Flow Set with Partial Order
Authors: Atamtürk Alper , Zhang Muhong 
Published: September 2008

The flow set with partial order is a mixed-integer set described by a budget on total flow and a partial order on the arcs that may carry positive flow. This set is a common substructure of resource allocation and scheduling problems with precedence constraints and robust network flow problems under demand/capacity uncertainty. We give a polyhedral analysis of the convex hull of the flow set with partial order. Unlike for the flow set without partial order, cover-type inequalities based on partial order structure are a function of a lifting sequence. We study the lifting sequences and describe structural results on the lifting coefficients for general and simpler special cases. We show that all lifting coefficients can be computed in polynomial time by solving maximum weight closure problems in general. For the special case of induced-minimal covers, we give a sequence-dependent characterization of the lifting coefficients. We prove, however, if the partial order is defined by an arborescence, then lifting is sequence-independent and all lifting coefficients can be computed in linear time. Moreover, if the partial order is defined by a path (total order), then the coefficients can be expressed explicitly. We also give a complete polyhedral description of the flow set with partial order for the polynomially-solvable total order case. We show that finding an optimal lifting order for a given induced-minimal cover and a given fractional solution is a submodular optimization problem, which is solved greedily. Finally, we present preliminary computational results with a cutting-plane algorithm based on the lifting and separation results.
Bevacizumab: A Treatment Option for Recurrent Glioblastoma Multiforme
Authors: Buie Larry W , Valgus John M 
Published: September 2008

Objective: To review the available literature evaluating the effect of bevacizumab on progression-free survival when used in combination with irinotecan for recurrent glioblastoma multiforme (GBM). Data Sources: Searches of MEDLINE (1966-June 2008), the Cochrane Library. and International Pharmaceutical Abstracts (1970-June 2008) were conducted using the terms bevacizumab. irinotecan, and glioblastoma multiforme. Study Selection And Data Extraction: The search was limited to studies conducted in humans. All articles identified trom the data sources were evaluated. All clinical trials evaluating the efficacy and safety of bevacizumab in the treatment of recurrent GBM were included in the review. Data Synthesis: Hypoxia, mutagenesis, and the secretion of various growth (actors can all lead to production of vascular endothelial growth factor (VEGF), a proangiogenic growth factor, and angiogenesis in GBM. Neoplastic progression is dependent on angiogenesis, and anti-VEGF therapy has been successful in multiple disease states. However, there are currently no available anti-VEGF therapies approved tor treatment of GBM. Bevacizumab is a humanized monoclonal antibody that binds to and inhibits the activity of VEGF. When compared with data from clinical trials that use single chemotherapeutic agents in recurrent GBM, the addition of bevacizumab to cytotoxic chemotherapy, such as irinotecan, appears to improve progression-Iree survival in patients progressing on the standard of care, with a 6-month progression-free survival rate of 46%. Bevacizumab is well tolerated by most patients, with modest risk (11% tn Phase 2 trials) of venous thromboembolism. Conclusions: Although the combination of bevacizumab and irinotecan is producing positive results in patients with recurrent GBM, larger, randomized clinical trials need to be performed to determine the magnitude of the benefit from bevacizumab. Bevacizumab administered biweekly at a dose of 10 mg/kg in combination with irinotecan may improve progression-free survival.
Bevacizumab Sterility in Multiple Doses from a Single-Use Vial
Authors: Örnek Kemal , Karahan Zeynep Ceren , Ergin Ahmet , Tekeli Alper , Tekeli Oya 
Published: September 2008

Background: Recent reports have demonstrated that refrigerated bevacizumab can be stored for up to 3 weeks at 4 °C without loss of efficacy. There have been no previous reports addressing bevacizumab's sterility when stored and used as multiple doses from a single-use vial. Objective: To evaluate the sterility of bevacizumab when used as multiple doses from a single-use vial. Methods: Four groups of vials were used to simulate the storage and use conditions for bevacizumab. Each group contained 11 doses of 0.2 mL of bevacizumab. One sample from each group was cultured once each day at 37 °C for 10 days; one sample from each group was left for 15 days. MacConkey agar, blood agar, thioglycollate broth, and Sabouraud medium were used to assess bacterial and fungal growth. Results: A total of 44 samples of bevacizumab were included in this study. Each sample was placed on 4 growth media for microbial readings. All samples were found to be negative for microbial growth. No significant differences were observed among the groups. Possible limitations of this study included the number of samples for each group and in vitro design of the study, which might have affected the growth of bacterial organisms. Conclusions: Storage and multiple use of bevacizumab from single-use vials does not seem to result in microbial contamination.
Activation of β-Catenin Signaling in Articular Chondrocytes Leads to Osteoarthritis-Like Phenotype in Adult β-Catenin Conditional Activation Mice
Authors: Zhu Mei , Tang Dezhi , Wu Qiuqian , Hao Suyang , Chen Mo , Xie Chao , Rosier Randy N , O'Keefe Regis J , Zuscik Michael , Chen Di 
Published: September 2008

Abstract
Osteoarthritis (OA) is a degenerative joint disease, and the mechanism of its pathogenesis is poorly understood. Recent human genetic association studies showed that mutations in the Frzb gene predispose patients to OA, suggesting that the Wnt/β-catenin signaling may be the key pathway to the development of OA. However, direct genetic evidence for β-catenin in this disease has not been reported. Because tissue-specific activation of the β-catenin gene (targeted by Col2a1-Cre) is embryonic lethal, we specifically activated the β-catenin gene in articular chondrocytes in adult mice by generating β-catenin conditional activation (cAct) mice through breeding of β-cateninfx(Ex3)/fx(Ex3) mice with Col2a1-CreERT2 transgenic mice. Deletion of exon 3 of the β-catenin gene results in the production of a stabilized fusion β-catenin protein that is resistant to phosphorylation by GSK-3β. In this study, tamoxifen was administered to the 3- and 6-mo-old Col2a1-CreERT2;β-cateninfx(Ex3)/wt mice, and tissues were harvested for histologic analysis 2 mo after tamoxifen induction. Overexpression of β-catenin protein was detected by immunostaining in articular cartilage tissues of β-catenin cAct mice. In 5-mo-old β-catenin cAct mice, reduction of Safranin O and Alcian blue staining in articular cartilage tissue and reduced articular cartilage area were observed. In 8-mo-old β-catenin cAct mice, cell cloning, surface fibrillation, vertical clefting, and chondrophyte/osteophyte formation were observed. Complete loss of articular cartilage layers and the formation of new woven bone in the subchondral bone area were also found in β-catenin cAct mice. Expression of chondrocyte marker genes, such as aggrecan, Mmp-9, Mmp-13, Alp, Oc, and colX, was significantly increased (3- to 6-fold) in articular chondrocytes derived from β-catenin cAct mice. Bmp2 but not Bmp4 expression was also significantly upregulated (6-fold increase) in these cells. In addition, we also observed overexpression of β-catenin protein in the knee joint samples from patients with OA. These findings indicate that activation of β-catenin signaling in articular chondrocytes in adult mice leads to the premature chondrocyte differentiation and the development of an OA-like phenotype. This study provides direct and definitive evidence about the role of β-catenin in the development of OA.
Inhibition of Lamin A/C Attenuates Osteoblast Differentiation and Enhances RANKL-Dependent Osteoclastogenesis
Authors: Rauner Martina , Sipos Wolfgang , Goettsch Claudia , Wutzl Arno , Foisner Roland , Pietschmann Peter , Hofbauer Lorenz C 
Published: September 2008

Abstract
Age-related osteoporosis is characterized by low bone mass, poor bone quality, and impaired osteoblastogenesis. Recently, the Hutchinson-Gilford progeria syndrome (HGPS), a disease of accelerated aging and premature osteoporosis, has been linked to mutations in the gene encoding for the nuclear lamina protein lamin A/C. Here, we tested the hypothesis that inhibition of lamin A/C in osteoblastic lineage cells impairs osteoblastogenesis and accelerates osteoclastogenesis. Lamin A/C was knocked-down with small interfering (si)RNA molecules in human bone marrow stromal cells (BMSCs) differentiating toward osteoblasts. Lamin A/C knockdown led to an inhibition of osteoblast proliferation by 26% and impaired osteoblast differentiation by 48% based on the formation of mineralized matrix. In mature osteoblasts, expression levels of runx2 and osteocalcin mRNA were decreased by lamin A/C knockdown by 44% and 78%, respectively. Furthermore, protein analysis showed that osteoblasts with diminished levels of lamin A/C also secreted less osteocalcin and expressed a lower alkaline phosphatase activity (−50%). Lamin A/C inhibition increased RANKL mRNA and protein levels, whereas osteoprotegerin (OPG) expression was decreased, resulting in an increased RANKL/OPG ratio and an enhanced ability to support osteoclastogenesis, as reflected by a 34% increase of TRACP+ multinucleated cells. Our data indicate that lamin A/C is essential for proper osteoblastogenesis. Moreover, lack of lamin A/C favors an osteoclastogenic milieu and contributes to enhanced osteoclastogenesis.
Analysis of CYP27B1, Encoding 25-Hydroxyvitamin D-1α-Hydroxylase, as a Candidate Tumor Suppressor Gene in Primary and Severe Secondary/Tertiary Hyperparathyroidism
Authors: Lauter Kelly , Arnold Andrew 
Published: September 2008

Abstract
CYP27B1, encoding 25-hydroxyvitamin D-1α-hydroxylase, converts 25-hydroxyvitamin D to its active form, 1,25-dihydroxyvitamin D, and is expressed primarily in the kidney but also in nontraditional sites including the parathyroid glands. Whereas the role of locally produced 1,25-dihydroxyvitamin D is not yet clear, it is possible that it contributes importantly to vitamin D–mediated inhibition of parathyroid cell growth, so CYP27B1 can be considered a candidate parathyroid tumor suppressor gene in that its acquired inactivation in a parathyroid cell could confer a tumorigenic growth advantage. Expression of CYP27B1 has also been reported to be altered in parathyroid neoplasms. Because detection of inactivating mutations is the central criterion for validating a candidate tumor suppressor, we directly sequenced the coding region and all splice sites of CYP27B1 in 31 sporadic parathyroid adenomas and 31 parathyroid tumors from patients with refractory secondary/tertiary hyperparathyroidism. No nonsense, frameshift, or other inactivating mutations were found, and there was no sign of homozygous deletion. Our findings indicate that CYP27B1 does not commonly serve as a classical tumor suppressor gene in the development of sporadic parathyroid adenomas or of refractory secondary/tertiary hyperparathyroidism.
CD33+ CD14− Phenotype Is Characteristic of Multinuclear Osteoclast-Like Cells in Giant Cell Tumor of Bone
Authors: Forsyth Ramses G , De Boeck Gitte , Baelde Johannes J , Taminiau Anthonie HM , Uyttendaele Dirk , Roels Hendrik , Praet Marleen M , Hogendoorn Pancras CW 
Published: September 2008

Abstract
Giant cell tumor of bone (GCTB) is a benign bone tumor with a shown clinical behavior of local recurrences and rare distant metastases. GCTB is composed of uniformly distributed osteoclastic giant cells, thought to originate from the fusion of monocyte–macrophage lineage cells, in a background consisting of mononuclear rounded cells and spindle-shaped cells. Several reports showed the specific expression of markers, such as CD14 on the mononuclear rounded cell population, however, lacking osteoclastic giant cells. Blood monocytes that were CD14+, CD33+, or CD14+/CD33+ have also been shown to be programmed as pre-osteoclasts. The macrophage marker CD33 is expressed earlier than CD14 in macrophage maturation, whereas CD14 is expressed longer than CD33. The aim of this study was to investigate CD14/CD33 expression profiles in GCTB. Nineteen GCTB tumor samples of 19 patients were studied. Immunofluorescent analyses were performed with monoclonal antibodies against CD14, CD33, RANK, and CD51. To unambiguously further prove the expression of these molecules, quantitative RT-PCR was used with subsequent sequencing of its products. All samples showed similar immunoreactivity profiles. The mononuclear rounded cell population was positive for RANK, CD51, CD14, and CD33. The osteoclastic giant cell population expressed RANK and CD51, as well as CD33, but was consistently negative for CD14 expression. The CD14 and CD33 profiles were confirmed by quantitative RT-PCR. These RT-PCR products were sequence verified. Osteoclasts in GCTB are the result of fusion of CD33-expressing pre-osteoclasts that further fuse with CD14+ mononuclear cells. Although these results reflect a static rather than a dynamic spectrum, we strongly believe that osteoclastogenesis seems not to be the exclusive result of fusion of intratumoral CD14+ mononuclear cells. Moreover, CD33-modulated osteoclastogenesis opens up the possibility for novel therapeutic directions.
Paget's Disease of Bone: Histologic Analysis of 754 Patients
Authors: Seitz Sebastian , Priemel Matthias , Zustin Jozef , Beil F Timo , Semler Jutta , Minne Helmut , Schinke Thorsten , Amling Michael 
Published: September 2008

Abstract
Although Paget's disease of bone (PDB) is the second most common metabolic bone disease, to our knowledge, there is only one quantitative analysis on the histological and especially on the histomorphometric level. Therefore, the aim of this study was to analyze, on the basis of the Hamburg Bone Register, PBD in terms of incidence, skeletal distribution, malignant transformation, and histological and histomorphometric characteristics. Bone biopsies and patient files of 754 cases with histologically proven PDB were reviewed in a retrospective study. Quantitative static histomorphometry was performed on a representative subgroup of 247 biopsies derived from patients with manifestation of PDB at the iliac crest and compared with an age- and sex-matched control group. The peak incidence of PDB was between 70 and 80 yr of age. The majority of monostotic skeletal manifestation was localized at the os ilium, followed by the spine and femur. Histomorphometric results showed a high bone turnover with a significant increase in bone resorption and bone formation indices leading to an increased bone volume. Paget sarcoma was diagnosed in 6 of 754 patients, indicating a malignant transformation in 0.8% of the affected patients. Taken together, our study characterizes PDB in Germany on the basis of one of the largest cohorts of patients with histologically proven PDB. Moreover, for the first time, a quantitative histomorphometric approach was taken for &gt;200 cases, where we could show local high bone mass lesions as a result of an increase of both osteoclast and osteoblast indices.