117 research outputs found

    Energy Calculations of The Realistic Quantum Slab

    Full text link
    We calculated the total energy of a semiconductor quantum dot which is defined by the trench gate method. In our calculation we used a recently developed energy functional called ``orbital-free energy functional". We compared the total energies obtained by Thomas-Fermi approximation, orbital-free energy functional and standard local-density approximation for the square quantum slab geometry. We have seen that this newly developed energy functional is numerically very efficient, superior to the Thomas-Fermi approximation and is in good agreement with the local-density approximation for two different sizes of quantum dot systems.Comment: 8 pages, 4 figure

    Mapping the stellar age of the Milky Way bulge with the VVV : II. Deep JK s catalog release based on PSF photometry

    Get PDF
    Context. The bulge represents the best compromise between old and massive Galactic components, and as such its study is a valuable opportunity to understand how the bulk of the Milky Way formed and evolved. In addition, being the only bulge in which we can individually resolve stars in all evolutionary sequences, the properties of its stellar content provide crucial insights into the formation of bulges. Aims. We are providing a detailed and comprehensive census of the Milky Way bulge stellar populations by producing deep and accurate photometric catalogs of the inner ∼300 deg 2 of the Galaxy. Methods. We performed DAOPHOT/ALLFRAME point spread function (PSF) fitting photometry of multi-epochs J and K s images provided by the VISTA Variables in the Vía Láctea (VVV) survey to obtain deep photometric catalogs. Artificial star experiments have been conducted on all images to properly assess the completeness and the accuracy of the photometric measurements. Results. We present a photometric database containing nearly 600 million stars across the bulge area surveyed by the VVV. Through the comparison of derived color-magnitude diagrams of selected fields representative of different levels of extinction and crowding, we show the quality, completeness and depth of the new catalogs. With the exception of the fields located along the plane, this new photometry samples stars down to ∼1-2 mag below the old main sequence turnoff with unprecedented accuracy. To demonstrate the tremendous potential inherent to this new dataset, we give a few examples of possible applications, including (i) star count studies through the dataset completeness map; (ii) surface brightness map; and (iii) cross-correlation with Gaia DR2. Conclusions. The database presented here represents an invaluable collection for the whole community, and we encourage its exploitation. The photometric catalogs including completeness information are publicly available through the ESO Science Archive as part of the MW-BULGE-PSPHOT release.Peer reviewedFinal Accepted Versio

    The effect of theoretical and simulation training on medical errors of nurse students in karadeniz technical university, Turkey

    Get PDF
    Objective: To assess the efficacy of theoretical training related to medical errors and patient safety and practical simulation training on students' knowledge and skill levels. Methods: This experimental study was conducted from March 28 to May 18, 2016, at nursing department of a university and comprised of students attending the third grade of the nursing school. The subjects were divided into two equal experimental and control groups. The experimental group, among other things, received simulation training that involved a demonstration and subsequent one-to-one practice. Data was collected on a proforma that included demographic information, pretest and post-test scores, checklists for pre-assessments and final assessments related to nursing practices. Results: There were 62 nurses divided into two groups of 31(50%) each. The difference between post-test scores of the concerning theoretical training about medical errors and patient safety was statistically significant (p0.05), while there was a significant difference between their final assessments (p<0.05). Conclusion: Theoretical education increased students' levels of knowledge regarding medical errors and patient safety, and the the practical simulation training reduced malpractices by improving skills. © 2018, Pakistan Medical Association. All rights reserved

    Mapping the stellar age of the Milky Way bulge with the VVV. I. The method

    Get PDF
    Recent observational programmes are providing a global view of the Milky Way bulge that serves as template for detailed comparison with models and extragalactic bulges. A number of surveys (i.e. VVV, GIBS, GES, ARGOS, BRAVA, APOGEE) are producing comprehensive and detailed extinction, metallicity, kinematics and stellar density maps of the Galactic bulge with unprecedented accuracy. However, the still missing key ingredient is the distribution of stellar ages across the bulge. To overcome this limitation, we aim to age-date the stellar population in several bulge fields with the ultimate goal of deriving an age map of the Bulge. This paper presents the methodology and the first results obtained for a field along the Bulge minor axis, at b=6b=-6^\circ. We use a new PSF-fitting photometry of the VISTA Variables in the V\'{i}a L\'{a}ctea (VVV) survey data to construct deep color-magnitude diagrams of the bulge stellar population down to \sim 2 mag below the Main Sequence turnoff. We find the bulk of the bulge stellar population in the observed field along the minor axis to be at least older than \sim 7.5 Gyr. In particular, when the metallicity distribution function spectroscopically derived by GIBS is used, the best fit to the data is obtained with a combination of synthetic populations with ages in between \sim 7.5 Gyr and 11 Gyr. However, the fraction of stars younger than \sim 10 Gyr strongly depends upon the number of Blue Straggler Stars present in the bulge. Simulations show that the observed color-magnitude diagram of the bulge in the field along the minor axis is incompatible with the presence of a conspicuous population of intermediate-age/young (i.e. 5\lesssim 5 Gyr) stars.Comment: 14 pages, 7 figues, Accepted for publication on A&

    The antioxidant activity of some curcuminoids and chalcones

    Get PDF
    The antioxidant properties of the synthetic compound (C1)–(C8), which comprised 7 curcuminoids and a chalcone, were evaluated by two complementary assays, DPPH and β-carotene/linoleic acid. It was found that, in general, the free radical scavenging ability of (C1)–(C8) was concentration-dependent. Compounds (C1) and (C4), which contained (4-OH) phenolic groups, were found to be highly potent antioxidants with higher antioxidant values than BHT suggesting that synthetic curcuminoids are more potent antioxidants than standard antioxidants like BHT. Using β-carotene-linoleic acid assay, only the water-soluble 2, 4,6-trihydroxyphenolic chalcone (C5) showed 85.2 % inhibition of the formation of conjugated dienes reflecting on its potent antioxidant activity

    COVID-19. Pandemic surgery guidance

    Get PDF
    Abstract – Based on high quality surgery and scientific data, scientists and surgeons are committed to protecting patients as well as healthcare staff and hereby provide this Guidance to address the special issues circumstances related to the exponential spread of the Coronavirus disease 2019 (COVID-19) during this pandemic. As a basis, the authors used the British Intercollegiate General Surgery Guidance as well as recommendations from the USA, Asia, and Italy. The aim is to take responsibility and to provide guidance for surgery during the COVID-19 crisis in a simplified way addressing the practice of surgery, healthcare staff and patient safety and care. It is the responsibility of scientists and the surgical team to specify what is needed for the protection of patients and the affiliated healthcare team. During crises, such as the COVID-19 pandemic, the responsibility and duty to provide the necessary resources such as filters, Personal Protective Equipment (PPE) consisting of gloves, fluid resistant (Type IIR) surgical face masks (FRSM), filtering face pieces, class 3 (FFP3 masks), face shields and gowns (plastic ponchos), is typically left up to the hospital administration and government. Various scientists and clinicians from disparate specialties provided a Pandemic Surgery Guidance for surgical procedures by distinct surgical disciplines such as numerous cancer surgery disciplines, cardiothoracic surgery, ENT, eye, dermatology, emergency, endocrine surgery, general surgery, gynecology, neurosurgery, orthopedics, pediatric surgery, reconstructive and plastic surgery, surgical critical care, transplantation surgery, trauma surgery and urology, performing different surgeries, as well as laparoscopy, thoracoscopy and endoscopy. Any suggestions and corrections from colleagues will be very welcome as we are all involved and locked in a rapidly evolving process on increasing COVID-19 knowledg

    The role of open abdomen in non-trauma patient : WSES Consensus Paper

    Get PDF
    The open abdomen (OA) is defined as intentional decision to leave the fascial edges of the abdomen un-approximated after laparotomy (laparostomy). The abdominal contents are potentially exposed and therefore must be protected with a temporary coverage, which is referred to as temporal abdominal closure (TAC). OA use remains widely debated with many specific details deserving detailed assessment and clarification. To date, in patients with intra-abdominal emergencies, the OA has not been formally endorsed for routine utilization; although, utilization is seemingly increasing. Therefore, the World Society of Emergency Surgery (WSES), Abdominal Compartment Society (WSACS) and the Donegal Research Academy united a worldwide group of experts in an international consensus conference to review and thereafter propose the basis for evidence-directed utilization of OA management in non-trauma emergency surgery and critically ill patients. In addition to utilization recommendations, questions with insufficient evidence urgently requiring future study were identified.Peer reviewe
    corecore