336 research outputs found

    Passiv damping on spacecraft sandwich panels

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    For reusable and expendable launch vehicles as well as for other spacecraft structural vibration loads are safety critical design drivers impacting mass and lifetime. Here, the improvement of reliability and safety, the reduction of mass, the extension of service life, as well as the reduction of cost for manufacturing are desired. Spacecraft structural design in general is a compromise between lightweight design and robustness with regard to dynamic loads. The structural stresses and strains due to displacements caused by dynamic loads can be reduced by mechanical damping based on passive or active measures. Passive damping systems can be relatively simple and yet are capable of suppressing a wide range of mechanical vibrations. Concepts are low priced in development, manufacturing and application as well as maintenancefree. Compared to active damping measures passive elements do not require electronics, control algorithms, power, actuators, sensors as well as complex maintenance. Moreover, a reliable application of active dampers for higher temperatures and short response times (e. g. re-entry environment) is questionable. The physical effect of passive dampers is based on the dissipation of load induced energy. Recent activities performed by OHB have shown the function of a passive friction-damping device for a vertical tail model of the German X-vehicle PHÖNIX but also for general sandwich structures. The present paper shows brand new results from a corresponding ESA-funded activity where passive damping elements are placed between the face sheets of large spacecraft relevant composite sandwich panels to demonstrate dynamic load reduction in vibration experiments on a shaker. Several passive damping measures are investigated and compared

    A New Source of Reaction - Diffusion Coupling in Confined Systems due to Temperature Inhomogeneity

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    Diffusion is often accompanied by a reaction or sorption which can induce temperature inhomogeneities. Monte Carlo simulations of Lennard-Jones atoms in zeolite NaCaA are reported with a hot zone presumed to be created by a reaction. Our simulations show that localised hot regions can alter both the kinetic and transport properties. Further, enhancement of the diffusion constant is greater for larger barrier height, a surprising result of considerable significance to many chemical and biological processes. We find an unanticipated coupling between reaction and diffusion due to the presence of hot zone in addition to that which normally exists via concentration.Comment: to be published in Phys. Rev. Let

    Practical management of riociguat in patients with pulmonary arterial hypertension

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    Riociguat is one of several approved therapies available for patients with pulmonary arterial hypertension (PAH). Treatment should be initiated and monitored at an expert center by a physician experienced in treating PAH, and the dose adjusted in the absence of signs and symptoms of hypotension. In certain populations, including patients with hepatic or renal impairment, the elderly, and smokers, riociguat exposure may differ, and dose adjustments should therefore be made with caution according to the established scheme. Common adverse events are often easily managed, particularly if they are discussed before starting therapy. Combination therapy with riociguat and other PAH-targeted agents is feasible and generally well tolerated, although the coadministration of phosphodiesterase type 5 inhibitors (PDE5i) and riociguat is contraindicated. An open-label, randomized study is currently ongoing to assess whether patients who do not achieve treatment goals while receiving PDE5i may benefit from switching to riociguat. In this review, we provide a clinical view on the practical management of patients with PAH receiving riociguat, with a focus on the opinions and personal experience of the authors. The reviews of this paper are available via the supplemental material section

    Urate Lowering Therapy with Febuxostat in Daily Practice—A Multicentre, Open-Label, Prospective Observational Study

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    Introduction. Febuxostat, a novel xanthine oxidase inhibitor for the treatment of symptomatic hyperuricemia, showed superiority over allopurinol in the reduction of serum uric acid levels in pivotal studies. Whether this holds true the FORTE (febuxostat in the oral urate lowering treatment: effectiveness and safety) study was conducted to evaluate treatment with febuxostat under daily practice conditions. Materials/Methods. The multicentre, open-label, and prospective observational study was conducted in 1,690 German medical practices from 9/2010 to 5/2011. Safety and efficacy data were assessed at baseline and week 4. Results. Data from 5,592 gout patients (72.6% male, mean age 63.7 years) were collected. Under urate lowering treatment with febuxostat mean serum uric acid levels decreased significantly from 8.9±1.9 mg/dL (534.0±114.6 μmol/L) at baseline to 6.2±2.5 mg/dL (372.0±150.0 μmol/L) at week 4. 67% which reached the mean uric acid target (6.1±1.0 mg/dL [366.0±59.4 μmol/L]). Only 43.1% of patients received concomitant flare prophylaxis. A total of 178 adverse events (mostly gout flares) were reported in 152 patients (2.6%). Conclusion. Febuxostat lowers serum uric acid levels effectively in routine clinical practice. Overall, treatment with febuxostat in both available dosages (80 mg/120 mg) was safe and well tolerated

    Saint Anselm of Canterbury and Charismatic Authority

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    The early career of Archbishop Anselm of Canterbury (c. 1033–1109) provides an opportunity to explore the operation of charismatic authority in a monastic setting. It is argued that the choice of Anselm for the archiepiscopal see of Canterbury in 1093 was the result of his growing reputation cultivated during his years as prior and abbot of the influential Norman monastery of Bec. The article explores various aspects of Anselm’s charismatic authority including his performance of charisma, the charisma derived from his fame as a scholar, and his reputation as a miracle-working holy man

    Objective, Subjective, and Self-Assessment of Preadolescent Orthodontic Treatment Need – A Function of Age, Gender, and Ethnic/Racial Background?

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    Children from socioeconomically disadvantaged and/or underrepresented minority backgrounds in the United States have limited or no access to orthodontic treatment. Objectives: To determine whether preadolescents' (a) objectively assessed orthodontic treatment need; (b) subjectively assessed orthodontic treatment need; and (c) self-perceptions of the psychologic aspects of their oral health-related quality of life and desire to have braces vary as a function of age, gender, ethnicity/race, and socioeconomic status (SES). Methods: Data were collected from 1,566 preadolescents (age range: 8 to 11 years; 47.3 percent male/52.7 percent female; 55.7 percent African-American/39.7 percent White/2.9 percent Hispanic) in oral exams and in face to face interviews. Malocclusion was determined with the Index of Orthodontic Treatment Need. Results: Children (17.2 percent) had definite treatment need, 33.7 percent were borderline, and 49.1 percent had little or no need. Objectively and subjectively assessed treatment need was not affected by the children's age or gender. However, girls were more critical of their smiles and wanted braces more than boys. The older the children were, the more critical they were and the more they wanted braces. African-American children and children in schools with higher percentages of children on free school lunches had less treatment need than White children and children in schools with lower percentages of students with free school lunches. While the provider-assessed treatment need was higher for White children than for Black children, Black children were less happy with their smiles than White children, and wanted braces more than White children. SES did not affect the children's self-perceptions. Conclusions: Findings showed that substantial percentages of the preadolescents have an orthodontic treatment need. Orthodontic need and child self-perceptions varied as a function of the children's age, gender, ethnicity/race, and SES.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65150/1/j.1752-7325.2008.00089.x.pd

    Mesiodistal root angulation of permanent teeth in children with mixed dentition and normal occlusion

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    OBJECTIVE: There is little information regarding the mesiodistal angulation of permanent teeth in mixed dentition. The aim of this study was to evaluate mesiodistal root angulation of permanent incisors, canines and first molars of 100 Brazilian children, using a new horizontal reference plane based on the midpoint of the intercuspation of primary canines and permanent first molars in panoramic radiographs during the mixed-dentition phase. MATERIAL AND METHODS: Children were equally divided between the genders with a mean age of 8.9 years (SD=0.76), normal occlusion and no eruptive disturbances. RESULTS: The angulation of the permanent maxillary first molars was close to the vertical, whereas the mandibular molars presented approximately 25 degrees of distal root angulation. The maxillary canines were the most distally angulated teeth, whereas the permanent mandibular canines were vertically positioned. The evaluation of the anterior maxillary area showed vertical position of permanent lateral, and central incisors with a slight distal angulation, whereas the permanent mandibular incisors tended to a mesial radicular convergence. CONCLUSIONS: The proposed reference line could be useful in mixed dentition root angulation evaluation; there was a slight asymmetry in the mesiodistal angulation among homologous teeth, and also a small variation between the male and the female groups, but no difference between 8-and 10-year-old children

    Wound healing protects against chemotherapy-induced alopecia in young rats via up-regulating interleukin-1β-mediated signaling

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    YesWound healing is a complex process regulated by various cell types and a plethora of mediators. While interactions between wounded skin and the hair follicles (HFs) could induce HF neogenesis or promote wound healing, it remains unknown whether the wound healing-associated signaling milieu can be manipulated to protect against alopecia, such as chemotherapy-induced alopecia (CIA). Utilizing a well-established neonatal rat model of CIA, we show here that skin wounding protects from alopecia caused by several clinically relevant chemotherapeutic regimens, and that protection is dependent on the time of wounding and hair cycle stage. Gene expression profiling unveiled a significant increase in interleukin-1 beta (IL-1β) mediated signaling by skin wounding. Subsequently, we showed that IL-1β is sufficient and indispensable for mediating the CIA-protective effect. Administration of IL-1β alone to unwounded rats exhibited local CIA protection while IL-1β neutralization abrogated CIA protection by wounding. Mechanistically, IL-1β retarded postnatal HF morphogenesis, making HFs at the wound sites or IL-1β treated areas damage-resistant while the rats developed total alopecia elsewhere. We conclude that wound healing switches the cutaneous cytokine milieu to an IL-1β-dominated state thus retarding HF growth progression and rendering the HFs resistant to chemotherapy agents. In the future, manipulation of HF progression through interfering with the IL-1β signaling milieu may provide therapeutic benefits to a variety of conditions, from prevention of CIA to inhibition of hair growth and treatment of hirsutism

    Contribution of serum lipids and cholesterol cellular metabolism in lung cancer development and progression

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    AbstractNeoplasms of the lungs are the leading cause of cancer incidence and mortality worldwide. Although immunotherapy has increased the overall survival of patients with lung cancer, there is the need to improve this treatment. At this regard, blood lipid levels are thought to be linked to cancer risk and thus a preventive intervention through regulation of the nutrition of patients with lung cancer is gaining much attention. In this study, we therefore asked about the contribution of serum lipids and cholesterol cellular metabolism in lung cancer development and progression. We measured different serum lipids and analyzed cholesterol synthesis enzymes 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGCR) and acetyl-coenzyme A cholesterol acetyltransferase 1 (ACAT1) as well as the cholesterol cellular export protein ATP-binding cassette (ABC) A-1 mRNA by quantitative PCR (qPCR) in the control and tumoral regions of post-surgery lung tissues to analyze the accumulation of cholesterol in cancer cells in a cohort of patients with lung adenocarcinoma (LUAD). We found that triglycerides in serum directly correlated with the body mass index (BMI) in patients with LUAD. By contrast, we found that high-density lipoprotein (HDL) cholesterol inversely correlated with the BMI, C-reactive protein (CRP) and overall survival and total cholesterol inversely correlated with the tumor diameter, serum CRP and overall survival in these LUAD patients. Functionally, the role of cholesterol is indispensable for the growth and development of normal animal cells where it is tightly regulated. Excess of cellular cholesterol regulated by HMGCR is converted to cholesteryl esters by the enzyme ACAT1 and exported extracellularly by the cholesterol transporter ABCA1. Here we found HMGCR and ACAT1 upregulated and ABCA1 downregulated in the lung’s tumoral region of our LUAD cohort, indicating cholesterol dysregulated cellular export in lung tumor cells.</jats:p
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