149 research outputs found

    Flora planine Aydogdu (Denizli / Turska)

    Get PDF
    The floristic characteristics of Mt Aydogdu (Denizli, Turkey) are presented and the vascular plant species growing in the area are documented. The study was carried out between 2000– 2003, and 1112 vascular plant samples were collected. At the end of the study, 586 taxa (at specific and infraspecific ranks) belonging to 82 families and 314 genera were identified. Asteraceae (76 species), Fabaceae (65 species) and Brassicaceae (43 species) are the largest families and Trifolium L. (13 species), Ornithogalum L. (9 species) and Veronica L. (9 species) are the largest genera in the area. The phytogeographic elements and their proportion represented in the study area are as follows: Mediterranean 180 (30.7%), Irano-Turanian 43 (7.3%), Euro-Siberian 24 (4.0%) and multiregional or of unknown phytogeographic origin 339 (58.0%). The endemism rate of the area is 9.7%, less then one third of the mean endemism rate in Turkey.U radu su prikazane florističke osobine planine Aydogdu (Denizli, Turska) i zabilježene su vrste vaskularnih biljaka koje rastu na tom području. Istraživanje je provedeno između 2000. i 2003., a prikupljeno je 1112 uzoraka vaskularnih biljaka. Na kraju istraživanja determinirano je sveukupno 586 svojti (na razini vrste i podvrste) iz 82 porodice i 314 rodova. Najzastupljenije porodice su Asteraceae (76 vrsta), Fabaceae (65 vrsta) i Brassicaceae (43 vrste), te rodovi Trifolium L. (13 vrsta), Ornithogalum L. (9 vrsta) i Veronica L. (9 vrsta). Fitogeografski elementi i njihov omjer je sljedeći: Mediteranski 180 (30.7%), Irano-Turanski 43 (7.3%), Eurosibirski 24 (4.0%) i multiregionalni ili nepoznatog fitogeografskog porijekla 339 (58.0%). Stupanj endemizma ovog područja je 9.7%, manje od jedne trećine srednje vrijednosti endemizma za Tursku

    Dyonic Kerr-Newman black holes, complex scalar field and Cosmic Censorship

    Full text link
    We construct a gedanken experiment, in which a weak wave packet of the complex massive scalar field interacts with a four-parameter (mass, angular momentum, electric and magnetic charges) Kerr-Newman black hole. We show that this interaction cannot convert an extreme the black hole into a naked sigularity for any black hole parameters and any generic wave packet configuration. The analysis therefore provides support for the weak cosmic censorship conjecture.Comment: Refined emphasis on the weak cosmic censorship conjecture, conclusions otherwise unchanged. Also, two sections merged, literature review updated, references added, a few typos correcte

    On the exactness of the Semi-Classical Approximation for Non-Relativistic One Dimensional Propagators

    Get PDF
    For one dimensional non-relativistic quantum mechanical problems, we investigate the conditions for all the position dependence of the propagator to be in its phase, that is, the semi-classical approximation to be exact. For velocity independent potentials we find that: (i) the potential must be quadratic in space, but can have arbitrary time dependence. (ii) the phase may be made proportional to the classical action, and the magnitude (``fluctuation factor'') can also be found from the classical solution. (iii) for the driven harmonic oscillator the fluctuation factor is independent of the driving term.Comment: 7 pages, latex, no figures, published in journal of physics

    Destroying black holes with test bodies

    Full text link
    If a black hole can accrete a body whose spin or charge would send the black hole parameters over the extremal limit, then a naked singularity would presumably form, in violation of the cosmic censorship conjecture. We review some previous results on testing cosmic censorship in this way using the test body approximation, focusing mostly on the case of neutral black holes. Under certain conditions a black hole can indeed be over-spun or over-charged in this approximation, hence radiative and self-force effects must be taken into account to further test cosmic censorship.Comment: Contribution to the proceedings of the First Mediterranean Conference on Classical and Quantum Gravity (talk given by T. P. S.). Summarizes the results of Phys. Rev. Lett. 103, 141101 (2009), arXiv:0907.4146 [gr-qc] and considers further example

    The Dirac Equation Is Separable On The Dyon Black Hole Metric

    Get PDF
    Using the tetrad formalism, we carry out the separation of variables for the massive complex Dirac equation in the gravitational and electromagnetic field of a four-parameter (mass, angular momentum, electric and magnetic charges) black hole.Comment: 13 page

    The standard "static" spherically symmetric ansatz with perfect fluid source revisited

    Full text link
    Considering the standard "static" spherically symmetric ansatz ds2 = -B(r) dt2 + A(r) dr2 + r2 dOmega2 for Einstein's Equations with perfect fluid source, we ask how we can interpret solutions where A(r) and B(r) are not positive, as they must be for the static matter source interpretation to be valid. Noting that the requirement of Lorentzian signature implies A(r) B(r) >0, we find two possible interpretations: (i) The nonzero component of the source four-velocity does not have to be u0. This provides a connection from the above ansatz to the Kantowski-Sachs (KS) spacetimes. (ii) Regions with negative A(r) and B(r) of "static" solutions in the literature must be interpreted as corresponding to tachyonic source. The combinations of source type and four-velocity direction result in four possible cases. One is the standard case, one is identical to the KS case, and two are tachyonic. The dynamic tachyonic case was anticipated in the literature, but the static tachyonic case seems to be new. We derive Oppenheimer-Volkoff-like equations for each case, and find some simple solutions. We conclude that new "simple" black hole solutions of the above form, supported by a perfect fluid, do not exist.Comment: 24 standard LaTeX pages, no figures. Some change in emphasis; changes in parametrizations of some of the solutions (ND2, TD2, TD3, NS1); one new solution (TS4); removal of an incorrect statement (about ND4

    Overcharging a Black Hole and Cosmic Censorship

    Get PDF
    We show that, contrary to a widespread belief, one can overcharge a near extremal Reissner-Nordstrom black hole by throwing in a charged particle, as long as the backreaction effects may be considered negligible. Furthermore, we find that we can make the particle's classical radius, mass, and charge, as well as the relative size of the backreaction terms arbitrarily small, by adjusting the parameters corresponding to the particle appropriately. This suggests that the question of cosmic censorship is still not wholly resolved even in this simple scenario. We contrast this with attempting to overcharge a black hole with a charged imploding shell, where we find that cosmic censorship is upheld. We also briefly comment on a number of possible extensions.Comment: 26 pages, 3 figures, LaTe

    Insulin Reduces Cerebral Ischemia/Reperfusion Injury in the Hippocampus of Diabetic Rats: A Role for Glycogen Synthase Kinase-3β

    Get PDF
    OBJECTIVE—There is evidence that insulin reduces brain injury evoked by ischemia/reperfusion (I/R). However, the molecular mechanisms underlying the protective effects of insulin remain unknown. Insulin is a well-known inhibitor of glycogen synthase kinase-3β (GSK-3β). Here, we investigate the role of GSK-3β inhibition on I/R-induced cerebral injury in a rat model of insulinopenic diabetes

    Holographic Derivation of Kerr-Newman Scattering Amplitudes for General Charge and Spin

    Get PDF
    Near-superradiant scattering of charged scalars and fermions by a near-extreme Kerr-Newman black hole and photons and gravitons by a near-extreme Kerr black hole are computed as certain Fourier transforms of correlators in a two-dimensional conformal field theory. The results agree with the classic spacetime calculations from the 1970s, thereby providing good evidence for a conjectured Kerr-Newman/CFT correspondence.Comment: 22 page

    Antimicrobial resistance among migrants in Europe: a systematic review and meta-analysis

    Get PDF
    BACKGROUND: Rates of antimicrobial resistance (AMR) are rising globally and there is concern that increased migration is contributing to the burden of antibiotic resistance in Europe. However, the effect of migration on the burden of AMR in Europe has not yet been comprehensively examined. Therefore, we did a systematic review and meta-analysis to identify and synthesise data for AMR carriage or infection in migrants to Europe to examine differences in patterns of AMR across migrant groups and in different settings. METHODS: For this systematic review and meta-analysis, we searched MEDLINE, Embase, PubMed, and Scopus with no language restrictions from Jan 1, 2000, to Jan 18, 2017, for primary data from observational studies reporting antibacterial resistance in common bacterial pathogens among migrants to 21 European Union-15 and European Economic Area countries. To be eligible for inclusion, studies had to report data on carriage or infection with laboratory-confirmed antibiotic-resistant organisms in migrant populations. We extracted data from eligible studies and assessed quality using piloted, standardised forms. We did not examine drug resistance in tuberculosis and excluded articles solely reporting on this parameter. We also excluded articles in which migrant status was determined by ethnicity, country of birth of participants' parents, or was not defined, and articles in which data were not disaggregated by migrant status. Outcomes were carriage of or infection with antibiotic-resistant organisms. We used random-effects models to calculate the pooled prevalence of each outcome. The study protocol is registered with PROSPERO, number CRD42016043681. FINDINGS: We identified 2274 articles, of which 23 observational studies reporting on antibiotic resistance in 2319 migrants were included. The pooled prevalence of any AMR carriage or AMR infection in migrants was 25·4% (95% CI 19·1-31·8; I2 =98%), including meticillin-resistant Staphylococcus aureus (7·8%, 4·8-10·7; I2 =92%) and antibiotic-resistant Gram-negative bacteria (27·2%, 17·6-36·8; I2 =94%). The pooled prevalence of any AMR carriage or infection was higher in refugees and asylum seekers (33·0%, 18·3-47·6; I2 =98%) than in other migrant groups (6·6%, 1·8-11·3; I2 =92%). The pooled prevalence of antibiotic-resistant organisms was slightly higher in high-migrant community settings (33·1%, 11·1-55·1; I2 =96%) than in migrants in hospitals (24·3%, 16·1-32·6; I2 =98%). We did not find evidence of high rates of transmission of AMR from migrant to host populations. INTERPRETATION: Migrants are exposed to conditions favouring the emergence of drug resistance during transit and in host countries in Europe. Increased antibiotic resistance among refugees and asylum seekers and in high-migrant community settings (such as refugee camps and detention facilities) highlights the need for improved living conditions, access to health care, and initiatives to facilitate detection of and appropriate high-quality treatment for antibiotic-resistant infections during transit and in host countries. Protocols for the prevention and control of infection and for antibiotic surveillance need to be integrated in all aspects of health care, which should be accessible for all migrant groups, and should target determinants of AMR before, during, and after migration. FUNDING: UK National Institute for Health Research Imperial Biomedical Research Centre, Imperial College Healthcare Charity, the Wellcome Trust, and UK National Institute for Health Research Health Protection Research Unit in Healthcare-associated Infections and Antimictobial Resistance at Imperial College London
    corecore