2,534 research outputs found

    Finite circular plate on elastic foundation centrally loaded by rigid spherical indenter

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    The analytical solution of a finite circular plate on an elastic foundation centrally loaded by the rigid indenter is discussed. The procedure to use NASTRAN as a subroutine to iteratively converge to this solution numerically is described

    A simple element for multilayer beams in NASTRAN thermal stress analysis

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    In the application of NASTRAN, structural members are usually represented by bar elements with multipoint constraint cards to enforce the interface conditions. While this is a very powerful method in principle, it was found that in practice the process for specification of constraints became tedious and error prone, unless the geometry was simple and the number of grid points low. An alternative approach was found within the framework of the NASTRAN program. This approach made use of the idea that a thermal distortion in a multilayer beam may be similar to a homogeneous beam with a thermal gradient across the cross section. The exact mathematical derivation for the equivalent beam, and all the necessary formulae for the equivalent parameters in NASTRAN analysis are presented. Some numerical examples illustrate the simplicity and ease of this approach for finite element analysis

    Training of postgraduates in Anatomy

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    It is recognized that training methods differ among the various medical colleges; however, trained specialists should be competent to discharge their duties independently in any part of the country. Therefore, to maintain uniform standards of education, there is a need to harmonize postgraduate training in anatomy. It is proposed that a structured training programme should be drawn up and monitored regularly at specified intervals, spelling out some clearly defined targets that need to be achieved. The ultimate goal of the postgraduate training programme should be to produce anatomists with sufficient knowledge and practical skills to undertake undergraduate teaching and evaluation in all branches of anatomy, as well as to pursue research independently

    A rare constellation of multiple upper limb anomalies

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    We describe an unusual combination of unilateral upper limb variations, including an axillary arch, absence of a “typical” musculocutaneous nerve, direct lateral cord innervation of the muscles usually supplied by the musculocutaneous nerve, variant superficial brachial artery, a high anomalous origin of the common interosseous artery and a superficial ulnar artery noted during routine cadaver dissection. The embryological basis, recent molecular insights concerning such a constellation of anomalies and its clinical relevance are discussed

    Quantitative study of cellular and volumetric growth of magnocellular and laminar auditory nuclei in developing chick brainstem

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    Development of the second and third order auditory nuclei-nucleus magnoscellularis (NM) and nucleus laminaris (NL) respectively-was studied using Nissl stained serial sections from brain specimens between 8 day of incubation and posthatch day 1, at every two day interval. Reconstruction of these nuclei from three incubation ages showed progressive growth of both nuclei in a rostrocaudal direction. The volume, total neuron, dead cell and glial cell numbers were estimated using stereological quantitation methods. Both nuclei, while undergoing an overall gradual increase in volume up to 20 days registered a transient drop in volume; earlier for NM at 10 days and later for NL at 18 days. From day 20 the two nuclei showed accelerated growth in volume. The total neuron count rapidly declined up to 12 days with 43% loss of neurons in NM followed by a rise and later stabilization within a certain range. The NL, however, showed a continuous fall in neuron numbers throughout the incubation period with 20% cell loss by day 12 and an overall loss of 52%. Cell death in both nuclei was maximal at 16 days and spanned the entire period of incubation. Glia showed a biphasic increase with peak at 14 days for both NM and NL followed by a subsequent rise at day 20 for both nuclei. These data would help in planning further experimental studies of auditory manipulation

    Age-related decrease in rod bipolar cell density of the human retina: an immunohistochemical study

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    During normal ageing, the rods (and other neurones) undergo a significant decrease in density in the human retina from the fourth decade of life onward. Since the rods synapse with the rod bipolar cells in the outer plexiform layer, a decline in rod density (mainly due to death) may ultimately cause an associated decline of the neurones which, like the rod bipolar cells, are connected to them. The rod bipolar cells are selectively stained with antibodies to protein kinase C-α. This study examined if rod bipolar cell density changes with ageing of the retina, utilizing donor human eyes (age: 6-91 years). The retinas were fixed and their temporal parts from the macula to the mid-periphery sectioned and processed for protein kinase C-α immunohistochemistry. The density of the immunopositive rod bipolar cells was estimated in the mid-peripheral retina (eccentricity: 3-5 mm) along the horizontal temporal axis. The results show that while there is little change in the density of the rod bipolar cells from 6 to 35 years (2.2%), the decline during the period from 35 to 62 years is about 21% and between seventh and tenth decades, it is approximately 27%

    Identification of Sesamin from Sesamum indicum as a Potent Antifungal Agent Using an Integrated in Silico and Biological Screening Platform

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    Due to the limited availability of antifungal drugs, their relevant side effects and considering the insurgence of drug-resistant strains, novel antifungal agents are urgently needed. To identify such agents, we have developed an integrated computational and biological screening platform. We have considered a promising drug target in antifungal drug discovery (exo-1,3-β-glucanase) and a phytochemical library composed of bioactive natural products was used. These products were computationally screened against the selected target using molecular docking and molecular dynamics techniques along with the evaluation of drug-like profile. We selected sesamin as the most promising phytochemical endowed with a potential antifungal profile and satisfactory drug-like properties. Sesamin was submitted to a preliminary biological evaluation to test its capability to inhibit the growth of several Candida species by calculating the MIC/MFC and conducting synergistic experiments with the marketed drug fluconazole. Following the screening protocol, we identified sesamin as a potential exo-1,3-β-glucanase inhibitor, with relevant potency in inhibiting the growth of Candida species in a dose-dependent manner (MIC and MFC of 16 and 32 μg/mL, respectively). Furthermore, the combination of sesamin with fluconazole highlighted relevant synergistic effects. The described screening protocol revealed the natural product sesamin as a potential novel antifungal agent, showing an interesting predicted pharmacological profile, paving the way to the development of innovative therapeutics against fungal infections. Notably, our screening protocol can be helpful in antifungal drug discovery

    Sex- and tissue-specific Bkm(GATA)-binding protein in the germ cells of heterogametic sex

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    The ZZ male/ZW female system of sex determination (female heterogamety) is found in snakes and birds whereas XY male/XX female system of sex determination (male heterogamety) operates in mammals including humans. The W and Y chromosomes are largely heterochromatic and undergo cycles of condensation and decondensation in the germ cells of ovary and testis, respectively, whereas they remain highly condensed and transcriptionally inactive in all somatic cells. Both chromosomes have enriched stretches of GATA repeats along their entire length (which is identified as banded krait minor satellite DNA and called Bkm) that are highly conserved through widely separated orders of eukaryotes. Here we report the existence of a factor, which specifically binds to Bkm, in the germ cells of the heterogametic sex (ovary in female heterogamety and testis in male heterogamety) where decondensation (activation) of the W and Y chromosomes, respectively, occurs; it has been purified as a polypeptide of 57.5 kDa from the rat snake ovary and designated as Bkm-binding protein (BBP) by virtue of its binding to GATA repeats of Bkm. Such a sex- and tissue-specific BBP is also present in the ovary of other species of snakes and in the testis of mouse and human where the Y chromosome is highly decondensed. We suggest that GATA repeats of Bkm brings about a coordinated decondensation of the W and Y sex chromosomes in the germ cells of the heterogametic sex in response to BBP which may serve as a "switch" for the activation of the genes present on the W and Y chromosomes

    On the True Nature of the Contact Binary CRTS J192848.7-404555

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    CRTS J192848.7-404555 was recognised as a potential contact binary merger candidate on the basis of survey photometry analysis. We have carried out follow up ground based photometry of the system and show that at the recorded coordinates for the system there are two stars approximately 3 seconds of arc apart. Our analysis shows that the fainter of the two stars is the actual variable while the slightly brighter star is of fixed brightness. In addition we show that the reported survey photometry is the result of both stars being treated as a single light source with resultant erroneous light curve solution. The true nature of CRTS J192848.7-404555 shows it to be a low mass contact binary system with a high mass ratio of 0.425, high amplitude of 0.69 magnitude and shallow 24% contact. The system does not have features of orbital instability and is not a potential merger progenitor.Comment: 7 Pages, 4 Figures Accepted: Astronomische Nachrichte
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