451 research outputs found

    Transition in a numerical model of contact line dynamics and forced dewetting

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    We investigate the transition to a Landau-Levich-Derjaguin film in forced dewetting using a quadtree adaptive solution to the Navier-Stokes equations with surface tension. We use a discretization of the capillary forces near the receding contact line that yields an equilibrium for a specified contact angle θΔ\theta_\Delta called the numerical contact angle. Despite the well-known contact line singularity, dynamic simulations can proceed without any explicit additional numerical procedure. We investigate angles from 15∘15^\circ to 110∘110^\circ and capillary numbers from 0.000850.00085 to 0.20.2 where the mesh size Δ\Delta is varied in the range of 0.00350.0035 to 0.060.06 of the capillary length lcl_c. To interpret the results, we use Cox's theory which involves a microscopic distance rmr_m and a microscopic angle θe\theta_e. In the numerical case, the equivalent of θe\theta_e is the angle θΔ\theta_\Delta and we find that Cox's theory also applies. We introduce the scaling factor or gauge function ϕ\phi so that rm=Δ/ϕr_m = \Delta/\phi and estimate this gauge function by comparing our numerics to Cox's theory. The comparison provides a direct assessment of the agreement of the numerics with Cox's theory and reveals a critical feature of the numerical treatment of contact line dynamics: agreement is poor at small angles while it is better at large angles. This scaling factor is shown to depend only on θΔ\theta_\Delta and the viscosity ratio qq. In the case of small θe\theta_e, we use the prediction by Eggers [Phys. Rev. Lett., vol. 93, pp 094502, 2004] of the critical capillary number for the Landau-Levich-Derjaguin forced dewetting transition. We generalize this prediction to large θe\theta_e and arbitrary qq and express the critical capillary number as a function of θe\theta_e and rmr_m. An analogy can be drawn between rmr_m and the numerical slip length.Comment: This version of the paper includes the corrections indicated in Ref. [1

    Mechanical properties of MWPECVD diamond coatings on Si substrate via nanoindentation

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    The mechanical properties of polycrystalline diamond coatings with thickness varying from 0.92 to 44.65 μm have been analysed. The tested samples have been grown on silicon substrates via microwave plasma enhanced chemical vapour deposition from highly diluted gas mixtures CH4–H2 (1% CH4 in H2). Reliable hardness and elastic modulus values have been assessed on lightly polished surface of polycrystalline diamond films. The effect of the coating thickness on mechanical, morphological and chemical-structural properties is presented and discussed. In particular, the hardness increases from a value of about 52 to 95 GPa and the elastic modulus from 438 to 768 GPa by varying the coating thickness from 0.92 to 4.85 μm, while the values closer to those of natural diamond (H=103 GPa and E=1200 GPa) are reached for thicker films (N5 μm). Additionally, the different thickness of the diamond coatings permits to select the significance of results and to highlight when the soft silicon substrate may affect the measured mechanical data. Thus, the nanoindentation experiments were made within the range from 0.65% to 10% of the film thickness by varying the maximum load from 3 to 80 mN. © 2010 Elsevier B.V. All rights reserve

    The Genetics Journey: A Case Report of a Genetic Diagnosis Made 30 Years Later

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    Mandibulofacial dysostosis with microcephaly (MFDM) is a rare autosomal dominant condition that was first described in 2006. The causative gene, EFTUD2, identified in 2012. We report on a family that initially presented to a pediatric genetics clinic in the 1980s for evaluation of multiple congenital anomalies. Re‐evaluation of one member thirty years later resulted in a phenotypic and molecularly confirmed diagnosis of MFDM. This family’s clinical histories and the novel EFTUD2 variant identified, c.1297_1298delAT (p.Met433Valfs*17), add to the literature about MFDM. This case presented several genetic counseling challenges and highlights that “the patient” can be multiple family members. We discuss testing considerations for an unknown disorder complicated by the time constraint of the patient’s daughter’s pregnancy and how the diagnosis changed previously provided recurrence risks. Of note, 1) the 1980s clinic visit letters provided critical information about affected family members and 2) the patient’s husband’s internet search of his wife’s clinical features also yielded the MFDM diagnosis, illustrating the power of the internet in the hands of patients. Ultimately, this case emphasizes the importance of re‐evaluation given advances in genetics and the value of a genetic diagnosis for both patient care and risk determination for family members.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147210/1/jgc40894.pd

    Acro-cardio-facial syndrome

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    Acro-cardio-facial syndrome (ACFS) is a rare genetic disorder characterized by split-hand/split-foot malformation (SHFM), facial anomalies, cleft lip/palate, congenital heart defect (CHD), genital anomalies, and mental retardation. Up to now, 9 patients have been described, and most of the reported cases were not surviving the first days or months of age. The spectrum of defects occurring in ACFS is wide, and both interindividual variability and clinical differences among sibs have been reported. The diagnosis is based on clinical criteria, since the genetic mechanism underlying ACFS is still unknown. The differential diagnosis includes other disorders with ectrodactyly, and clefting conditions associated with genital anomalies and heart defects. An autosomal recessive pattern of inheritance has been suggested, based on parental consanguinity and disease's recurrence in sibs in some families. The more appropriate recurrence risk of transmitting the disease for the parents of an affected child seems to be up to one in four. Management of affected patients includes treatment of cardiac, respiratory, and feeding problems by neonatal pediatricians and other specialists. Prognosis of ACFS is poor

    Early observed transient prostate-specific antigen elevations on a pilot study of external beam radiation therapy and fractionated MRI guided High Dose Rate brachytherapy boost

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    PURPOSE: To report early observation of transient PSA elevations on this pilot study of external beam radiation therapy and magnetic resonance imaging (MRI) guided high dose rate (HDR) brachytherapy boost. MATERIALS AND METHODS: Eleven patients with intermediate-risk and high-risk localized prostate cancer received MRI guided HDR brachytherapy (10.5 Gy each fraction) before and after a course of external beam radiotherapy (46 Gy). Two patients continued on hormones during follow-up and were censored for this analysis. Four patients discontinued hormone therapy after RT. Five patients did not receive hormones. PSA bounce is defined as a rise in PSA values with a subsequent fall below the nadir value or to below 20% of the maximum PSA level. Six previously published definitions of biochemical failure to distinguish true failure from were tested: definition 1, rise >0.2 ng/mL; definition 2, rise >0.4 ng/mL; definition 3, rise >35% of previous value; definition 4, ASTRO defined guidelines, definition 5 nadir + 2 ng/ml, and definition 6, nadir + 3 ng/ml. RESULTS: Median follow-up was 24 months (range 18–36 mo). During follow-up, the incidence of transient PSA elevation was: 55% for definition 1, 44% for definition 2, 55% for definition 3, 33% for definition 4, 11% for definition 5, and 11% for definition 6. CONCLUSION: We observed a substantial incidence of transient elevations in PSA following combined external beam radiation and HDR brachytherapy for prostate cancer. Such elevations seem to be self-limited and should not trigger initiation of salvage therapies. No definition of failure was completely predictive

    Concurrent Outbreak of Norovirus Genotype I and Enterotoxigenic Escherichia coli on a U.S. Navy Ship following a Visit to Lima, Peru

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    An outbreak of norovirus (NoV) genotype I and Enterotoxigenic Escherichia coli (ETEC) occurred among US Navy Ship personnel following a visit to Lima, Peru, in June 2008. Visiting a specific area in Lima was significantly associated with illness. While ETEC and NoV are commonly recognized as causative agents of outbreaks, co-circulation of both pathogens has been rarely observed in shipboard outbreaks

    The Influence of Organizational Context on Quitting Intention

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    This study uses multilevel methods to investigate the effects of organizational context on job satisfaction and quitting intention among staff working in long-term mental health care settings. Two types of organizational features are examined: group job satisfaction and structural features of the work unit (unit size, workload, and level of client functioning on the unit). A review of the organizational literature reveals that most empirical research has investigated job satisfaction at the individual level of analysis rather than the group level. The authors argue that the affective context of a group has real and measurable consequences for individual attitudes and behavior, independent of individual attitudes toward the job. Using multilevel modeling, study findings support the premise that group job satisfaction exercises effects on intention to quit independent of individuals’ dispositions toward their jobs. These effects are both direct and interactive. The findings underscore the importance of affective context in shaping individual attitudes and behavioral intentions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68775/2/10.1177_0164027599212003.pd
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