757 research outputs found

    Role of optimization in interdisciplinary analyses of naval structures

    Get PDF
    The need for numerical design optimization of naval structures is discussed. The complexity of problems that arise due to the significant roles played by three major disciplines, i.e., structural mechanics, acoustics, and hydrodynamics are discussed. A major computer software effort that has recently begun at the David W. Taylor Naval Ship R&D Center to accommodate large multidisciplinary analyses is also described. In addition to primarily facilitating, via the use of data bases, interdisciplinary analyses for predicting the response of the Navy's ships and related structures, this software effort is expected to provide the analyst with a convenient numerical workbench for performing large numbers of analyses that may be necessary for optimizing the design performance. Finally, an example is included that investigates several aspects of optimizing a typical naval structure from the viewpoints of strength, hydrodynamic form, and acoustic characteristics

    Optimization and transformation of Arundo donax L. using particle bombardment

    Get PDF
    An optimized particle bombardment protocol to introduce DNA into Arundo donax L. (giant reed) embryogenic callus cells was developed. The physical and biological parameters tested for optimal transient expression of ß-glucuronidase (GUS) and green fluorescent protein (GFP) genes were: helium pressure, distance from stopping screen to target tissue and vacuum pressure together with other factors such as gold microparticle size, DNA concentration and the number of bombardments. The highest transient GUS and GFP expression was obtained when cells were bombarded twice at 1100 psi, with 9 cm target distance, 24 mm Hg vacuum pressure, 1 mm gold particle size, 1.5 mg DNA per bombardment, three days pre-culture prior to bombardment and six days post bombardment culture. This is the first report of optimization of particle bombardment parameters for high-efficiency DNA delivery combined with minimum damage to target giant reed tissues.Key words: Arundo donax, particle bombardment, ß-glucuronidase (GUS), green fluorescent protein (GFP), transient gene expression, genetic transformation

    Calcretes in the Thar desert: genesis, chronology and palaeoenvironment

    Get PDF
    The calcretes in the Thar desert occur in a variety of settings, including the piedmonts, sheetwash aggraded plains; and this study adds calcretes in regolith and colluvio-alluvial plains to the group of settings in which calcretes occur in the region. Field logs, morphological details and analytical data such as petrographic, cathodoluminescence and geochemical characteristics are described along with a discussion on their implications. Sand dunes and sandy plains dating to <20 ka have weakly developed calcretes. The better-developed calcrete horizons occur in piedmonts, interdunes or in areas that have sufficient groundwater. Deep sections in the region show phases of calcrete development in aeolian sand aggradation at ~150, ~100, ~60 and 27-14 ka. The extensive sheetwash plains have mature calcretes and date to mid-Pleistocene. Our studies indicate that these calcretes represent a hybrid process, where carbonate enrichment of the originally calcareous host occurred due to periodically raised groundwaters, and its differentiation into nodules occurred under subaerial environment i.e., after recession of groundwater. Deep sections also show a stack of discrete calcretes that developed in individual aggradation episodes with hiatuses as indicated by ESR dating results. Nodules display a multiplicity of carbonate precipi tation events and internal reorganization of calcitic groundmass. The process is accompanied by degradation and transformation of unstable minerals, particularly clays and with a neosynthesis of palygorskite. The ancient calcretes are dated from the beginning of the Quaternary to ~600 ka and show more evolved morphologies marked by brecciation, dissolution, laminar growth on brecciated surfaces, pisolites and several generations of re-cementation. Mica/chlorite schists and such other rocks are particularly vulnerable to replacement by carbonate. In an extreme case, replacement of quartzose sandstone was observed also. The presence of stretches of alluvio-colluvial plains in an area presently devoid of drainage bespeaks of occasional high-energy fluvial regime, under a semi-arid climate. The mid-Pleistocene period saw a shift towards more arid climate and this facilitated sheetwash aggradation. Finally, during the late Pleistocene, aggradation of aeolian sands indicated a progressively drier climate. However, this does not find its reflection in stable isotope data. The amount of carbonate in the form of calcretes is substantial. The present studies indicate that aeolian dust or rainwater are minor contributors to the carbonate budget. A more important source was provided by the pre-existing calcretes in the sheetwash aggraded plains and detrital carbonate in the aeolian sediments. The original source of carbonate in the region, however, remains unresolved and will need further investigations. Electron spin resonance protocols for the dating of calcretes were developed as a part of this study and the results accorded well with geological reasoning

    Demographics, Personality and Substance-Use Characteristics Associated with Forming Romantic Relationships

    Get PDF
    The current study aimed to identify demographic, personality and substance-use characteristics associated with forming romantic relationships. Data were collected by two online surveys among students in Bergen, Norway, during the autumn of 2015 (T1) and by a follow-up survey that was conducted 12 months later (T2). The current sample consists of the 2404 participants who reported being single at T1 (mean age 23.2) and who participated in both waves of the survey. Binary logistic regression analyses were conducted. Separate analyses were conducted for both sexes and for the entire sample of participants. High extroversion scores predicted relationship formation. For women, having a child/children, higher scores on neuroticism, alcohol use and illegal substance use positively predicted relationship formation, while for men, age and openness were positive predictors. The study contributes with several novel findings. In general, characteristics related to a need for support predicted romantic relationship formation among women, while characteristics associated with increased resource acquisition potential predicted relationship formation among men. The general pattern of findings is in line with established evolutionary theories such as the sexual strategies theory and the parental investment theory.Peer reviewe

    Void Fraction Measurements during Saturated Pool Boiling of Water on Partially Wetted Vertical Surfaces,”

    Get PDF
    Introduction Of all the modes of boiling, nucleate boiling is associated with the highest heat transfer coefficients. As a result, this process is of great interest with regard to applications as well as basic understanding. Numerous studies of nucleate boiling heat transfer have been reported in the literature. The results of these studies have generally been given in the form of correlations. So far, relatively few attempts have been made to describe the nucleate boiling process in a mechanistic way, and those efforts have met with little success. The primary cause for the very limited success of those attempts is a lack of understanding of the interaction of several surface and fluid parameters. To facilitate further development of mechanistic models of nucleate boiling and maximum heat fluxes, the purpose of the present work is to determine experimentally the interplay between the wall void fraction, surface wettability, and vapor flow dynamics away from the wall. The earliest correlation for nucleate boiling is that o

    Qualitative and Mixed Methods Social Media Research: A Review of the Literature

    Get PDF
    Social media technologies have attracted substantial attention among many types of users including researchers who have published studies for several years. This article presents an overview of trends in qualitative and mixed methods social media research literature published from 2007 through 2013. A collection of 229 qualitative studies were identified through a systematic literature review process. A subset of 55 of these articles report studies involving a combination of qualitative and quantitative methods. Articles were reviewed, analyzed, and coded through a qualitative content analysis approach. Overall trends are presented with respect to the entire collection of articles followed by an analysis of mixed methods research approaches identified in the subset of 55 studies. The most commonly used research approaches involved collecting data from people through interview, focus group, and survey methodologies. Content analysis was the second most commonly used approach whereby researchers use Facebook posts, Tweets (Twitter posts), YouTube videos, or other social media content as a data source. Many of the studies involving combinations of quantitative and qualitative data followed a design resembling Creswell and Plano Clark’s basic mixed methods typology (e.g., convergent parallel, explanatory sequential, and exploratory sequential)

    NLO QCD Corrections to BcB_c-to-Charmonium Form Factors

    Full text link
    The Bc(1S0)B_c(^1S_0) meson to S-wave Charmonia transition form factors are calculated in next-to-leading order(NLO) accuracy of Quantum Chromodynamics(QCD). Our results indicate that the higher order corrections to these form factors are remarkable, and hence are important to the phenomenological study of the corresponding processes. For the convenience of comparison and use, the relevant expressions in asymptotic form at the limit of mc0m_c\rightarrow0 for the radiative corrections are presented

    General and Alcohol-Related Social Media Use and Mental Health: a Large-Sample Longitudinal Study

    Get PDF
    The current study aimed to investigate if general and alcohol-related social media use predicts symptoms of depression and anxiety. Students in Bergen, Norway, participated in a Web-based survey during fall 2015 (T1) and a follow-up survey during fall 2016 (T2). A total of 5217 participated in both surveys. Crude and adjusted linear regression analyses were conducted to investigate if social media use at T1 predicted depression and anxiety at T2. Several social media use variables (e.g., using Instagram) were positively associated with depression and anxiety over time, but these associations became non-significant when covariates were controlled for. Number of online friends was inversely related to depression whereas using Twitter was positively related to anxiety at T2, when covariates were controlled for. The effect sizes of the observed associations were all very small. The current study found little support for a relationship between social media use and mental health

    Validation and utilization of a TFE3 break-apart FISH assay for Xp11.2 translocation renal cell carcinoma and alveolar soft part sarcoma

    Get PDF
    Background: Xp11.2 or TFE3 translocation renal cell carcinomas (RCC) and alveolar soft part sarcoma (ASPS) are characterized by chromosome translocations involving the Xp11.2 breakpoint resulting in transcription factor TFE3 gene fusions. The most common translocations documented in TFE3 RCCs are t(X;1) (p11.2;q21) and t(X;17) (p11.2;q25) which leads to fusion of TFE3 gene on Xp11.2 with PRCC or ASPL respectively. TFE3 immunohistochemistry (IHC) has been inconsistent over time due to background staining problems in part related to fixation issues. Karyotyping to detect TFE3 gene rearrangement requires typically unavailable fresh tissue. Reverse transcriptase-polymerase chain reaction (RT-PCR) is generally very challenging due to degradation of RNA in archival material. The study objective was to develop and validate a TFE3 break-apart fluorescence in situ hybridization (FISH) assay to confirm Xp11 translocation RCCs and ASPS. Methods: Representative sections of formalin-fixed paraffin-embedded tissue blocks were selected in 40 possible cases. Approximately 60 tumor cells were analyzed in the targeted region. The validation of TFE3 FISH was done with 11 negative and two positive cases. Cut off for a positive result was validated as >7.15 % positive nuclei with any pattern of break-apart signals. FISH evaluation was done blinded of the immunohistochemical or karyotype data. Results: Three out of forty cases were positive for the TFE3 break-apart signals by FISH. The negative cases were reported as clear cell RCC with papillary features (10), clear cell RCC with sarcomatoid areas (2), Papillary RCC with clear cell areas (9), Chromophobe RCC (2), RCC, unclassified type (3) and renal medullary carcinoma (1). 3 of the negative cases were consultation cases for renal tumor with unknown histology. Seven negative cases were soft tissue tumor suspicious for ASPS. Conclusion: Our study validates the utility of TFE3 break-apart FISH on formalin-fixed paraffin-embedded tissue sections for diagnosis and confirmation of Xp11.2 translocation RCCs and ASPS

    Properties of Light Flavour Baryons in Hypercentral quark model

    Full text link
    The light flavour baryons are studied within the quark model using the hyper central description of the three-body system. The confinement potential is assumed as hypercentral coulomb plus power potential (hCPPνhCPP_\nu) with power index ν\nu. The masses and magnetic moments of light flavour baryons are computed for different power index, ν\nu starting from 0.5 to 1.5. The predicted masses and magnetic moments are found to attain a saturated value with respect to variation in ν\nu beyond the power index ν>\nu> 1.0. Further we computed transition magnetic moments and radiative decay width of light flavour baryons. The results are in good agreement with known experimental as well as other theoretical models.Comment: Accepted in Pramana J. of Physic
    corecore