3,260 research outputs found

    Horizon of quantum black holes in various dimensions

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    We adapt the horizon wave-function formalism to describe massive static spherically symmetric sources in a general (1+D)(1+D)-dimensional space-time, for D>3D>3 and including the D=1D=1 case. We find that the probability PBHP_{\rm BH} that such objects are (quantum) black holes behaves similarly to the probability in the (3+1)(3+1) framework for D>3D> 3. In fact, for D3D\ge 3, the probability increases towards unity as the mass grows above the relevant DD-dimensional Planck scale mDm_D. At fixed mass, however, PBHP_{\rm BH} decreases with increasing DD, so that a particle with mass mmDm\simeq m_D has just about 10%10\% probability to be a black hole in D=5D=5, and smaller for larger DD. This result has a potentially strong impact on estimates of black hole production in colliders. In contrast, for D=1D=1, we find the probability is comparably larger for smaller masses, but PBH<0.5P_{\rm BH} < 0.5, suggesting that such lower dimensional black holes are purely quantum and not classical objects. This result is consistent with recent observations that sub-Planckian black holes are governed by an effective two-dimensional gravitation theory. Lastly, we derive Generalised Uncertainty Principle relations for the black holes under consideration, and find a minimum length corresponding to a characteristic energy scale of the order of the fundamental gravitational mass mDm_D in D>3D>3. For D=1D=1 we instead find the uncertainty due to the horizon fluctuations has the same form as the usual Heisenberg contribution, and therefore no fundamental scale exists.Comment: Latex, 16 pages, 8 figures. Final version to appear in PL

    National Differences in the Prevalence of Depressive Symptoms in Mania: a Naturalistic Study Using the Dsm-5 'with Mixed Features' Specifier M.I.N.I. Module

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    Introduction In bipolar I disorder (BD1), manic episodes with depressive symptoms are generally more severe than pure manic episodes, but are not easily identified. The DSM-5 'With Mixed Features' specifier, and accompanying patient-rated Mini-International Neuropsychiatric Interview (M.I.N.I.) module, were designed to aid diagnosis. Objectives To examine patients with BD1 who have mania with depressive symptoms, across countries. Aims To improve the identification of depressive symptoms during a BD1 manic episode. Methods This naturalistic study surveyed psychiatrists and their patients with BD1 (manic episode within previous 3 months), in Germany, Italy, Spain, UK, Turkey, Australia, Brazil and Canada. Psychiatrists provided information on depressive symptoms (DSM-5 'With Mixed Features' specifier plus patient-rated M.I.N.I. module); anxiety, irritability, and agitation; suicide attempts; and treatment response. Results Of 1,035 bipolar patients, 34% had mania 'With Mixed Features'(≥05;3 depressive symptoms), and displayed more severe symptoms, and higher rates of attempted suicide than patients without mixed features. Across countries, severe anxiety occurred in 3.5–19.5% of patients; severe irritability in 4.3–17.0%; and severe agitation in 4.3–19.6%. The proportion of patients experiencing 'prominent dysphoria or depressed mood' was highest in Italy (64.2%). Recurrent suicidal ideation ranged from 8.0% (Germany) to 25.7% (Spain); lifetime rate of attempted suicide was highest in Canada (64.7%). Between-country differences were also reflected in the M.I.N.I. module outcomes. Conclusion Patients with BD1 'With Mixed Features', suffer from a greater burden of disease than patients with pure mania, and there is variation between countries – as detected by physician and patient evaluations

    The edge of galaxy formation III: The effects of warm dark matter on Milky Way satellites and field dwarfs

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    In this third paper of the series, we investigate the effects of warm dark matter with a particle mass of mWDM=3keVm_\mathrm{WDM}=3\,\mathrm{keV} on the smallest galaxies in our Universe. We present a sample of 21 hydrodynamical cosmological simulations of dwarf galaxies and 20 simulations of satellite-host galaxy interaction that we performed both in a Cold Dark Matter (CDM) and Warm Dark Matter (WDM) scenario. In the WDM simulations, we observe a higher critical mass for the onset of star formation. Structure growth is delayed in WDM, as a result WDM haloes have a stellar population on average two Gyrs younger than their CDM counterparts. Nevertheless, despite this delayed star formation, CDM and WDM galaxies are both able to reproduce the observed scaling relations for velocity dispersion, stellar mass, size, and metallicity at z=0z=0. WDM satellite haloes in a Milky Way mass host are more susceptible to tidal stripping due to their lower concentrations, but their galaxies can even survive longer than the CDM counterparts if they live in a dark matter halo with a steeper central slope. In agreement with our previous CDM satellite study we observe a steepening of the WDM satellites' central dark matter density slope due to stripping. The difference in the average stellar age for satellite galaxies, between CDM and WDM, could be used in the future for disentangling these two models.Comment: 10 pages, 11 figures, accepted for publication on MNRA

    Association of malalignment, muscular dysfunction, proprioception, laxity and abnormal joint loading with tibiofemoral knee osteoarthritis - a systematic review and meta-analysis

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    Background: To investigate (1) the association of specific biomechanical factors with knee osteoarthritis and knee osteoarthritis development, and (2) the impact of other relevant risk factors on this association.Methods: MEDLINE, EMBASE, CINAHL and SPORTDiscus were searched up until April 2017. Studies were included if they fulfilled the following criteria: the study 1) assessed the association of a biomechanical factor with knee osteoarthritis, or knee osteoarthritis development; 2) reported on skeletal malalignment, muscular dysfunction, impaired proprioception, laxity and abnormal loading during gait; 3) was a cohort study with participants developing knee osteoarthritis and participants not developing knee osteoarthritis, or a case-control or cross-sectional study with participants with knee osteoarthritis and without knee osteoarthritis. Risk of bias was assessed with the QUIPS tool and meta-analyses were performed using random effects models.Results: Of 6413 unique studies identified, 59 cross-sectional studies were eligible for meta-analyses (9825 participants, 5328 with knee osteoarthritis). No cohort studies fulfilled the inclusion criteria. Compared with healthy controls, patients with knee osteoarthritis have higher odds of having lower muscle strength, proprioception deficits, more medial varus-valgus laxity and less lateral varus-valgus laxity. Patients with medial knee osteoarthritis have higher odds of having a higher knee adduction moment than healthy controls. Level of evidence was graded as 'very low' to 'moderate' quality. Due to large between study differences moderation of other risk factors on biomechanical risk factors could not be evaluated.Conclusions: Patients with knee osteoarthritis are more likely to display a number of biomechanical characteristics. The causal relationship between specific biomechanical factors and the development of knee osteoarthritis could not be determined as no longitudinal studies were included. There is an urgent need for high quality, longitudinal studies to evaluate the impact of specific biomechanical factors on the development of knee osteoarthritis.Trial Registration: (PROSPERO ID: CRD42015025092)

    Szenarien zum Pflegebedarf und -potenzial in einer Großstadt: das Beispiel Köln

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    Welche Auswirkungen haben Alterung, Veränderung der Einwohnerstruktur und eine zunehmende Internationalisierung auf die zukünftige Pflegebedürftigkeit und das Pflegepotenzial in der Stadt Köln? Um Antworten auf diese Fragen geben zu können, zeigt der Beitrag Szenarien auf, die zum einen den Umfang der zukünftigen Pflegebedürftigkeit umfassen und zum anderen die Art der Pflege skizzieren. Neben der Analyse statistischer Daten zur aktuellen Situation der Pflegebedürftigkeit in Köln und den prognostizierten Einwohnerentwicklungen wird basierend auf Umfrageergebnissen die Pflegesituation aus Sicht der Kölnerinnen und Kölner dargestellt. Die Ergebnisse verdeutlichen, dass die Mehrheit im Falle einer Pflegebedürftigkeit auf eine Versorgung und Unterstützung von Verwandten und Bekannten hofft. Während die Zahl der Pflegebedürftigen steigt, geht jedoch das informelle Pflegepotenzial zurück. Um die heutige häusliche Pflegequote erhalten zu können, müssten zukünftig deutlich mehr Angehörige als bislang häusliche Pflege übernehmen. Darüber hinaus zeigt die Analyse auch, dass die Einstellung zu Pflege in engem Zusammenhang zu Werteeinstellungen und zum ökonomischen Status steht. Im Zuge einer – zwar derzeit auf geringem Niveau – ansteigenden Altersarmut stellen sich neue Herausforderungen an Pflege und Pflegeangebote

    Is Steam Explosion a Promising Pretreatment for Acid Hydrolysis of Lignocellulosic Biomass?

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    For the production of sugars and biobased platform chemicals from lignocellulosic biomass, the hydrolysis of cellulose and hemicelluloses to water-soluble sugars is a crucial step. As the complex structure of lignocellulosic biomass hinders an efficient hydrolysis via acid hydrolysis, a suitable pretreatment strategy is of special importance. The pretreatment steam explosion was intended to increase the accessibility of the cellulose fibers so that the subsequent acid hydrolysis of the cellulose to glucose would take place in a shorter time. Steam explosion pretreatment was performed with beech wood chips at varying severities with different reaction times (25–34 min) and maximum temperatures (186–223 °C). However, the subsequent acid hydrolysis step of steam-exploded residue was performed at constant settings at 180 °C with diluted sulfuric acid. The concentration profiles of the main water-soluble hydrolysis products were recorded. We showed in this study that the defibration of the macrofibrils in the lignocellulose structure during steam explosion does not lead to an increased rate of cellulose hydrolysis. So, steam explosion is not a suitable pretreatment for acid hydrolysis of hardwood lignocellulosic biomass

    Parameter Estimation of Linear Dynamical Systems with Gaussian Noise

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    We present a novel optimization-based method for parameter estimation of a time-varying dynamic linear system. This method optimizes the likelihood of the parameters given measured data using an optimization algorithm tailored to the structure of this maximum likelihood estimation problem. Some parameters of the covariance of process and measurement noise can also be estimated. This is particularly useful when offset-free Model Predictive Control with a linear disturbance model is performed. To reduce the complexity of the maximum likelihood estimation problem we also propose an approximate formulation and show how it is related to the actual problem. We present the advantages of the proposed approach over commonly used methods in the framework of Moving Horizon Estimation. We also present how to use Sequential Quadratic Programming efficiently for the optimization of our formulations. Finally, we show the performance of the proposed methods through numerical simulations. First, on a minimal example with only one parameter to be estimated, and second, on a system with heat and mass transfer. Both methods can successfully estimate the model parameters in these examples.Comment: Submitted to IEEE European Control Conference 2023 (ECC23). Contains 8 pages including 6 figure
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