3,260 research outputs found
Horizon of quantum black holes in various dimensions
We adapt the horizon wave-function formalism to describe massive static
spherically symmetric sources in a general -dimensional space-time, for
and including the case. We find that the probability
that such objects are (quantum) black holes behaves similarly to the
probability in the framework for . In fact, for , the
probability increases towards unity as the mass grows above the relevant
-dimensional Planck scale . At fixed mass, however,
decreases with increasing , so that a particle with mass has
just about probability to be a black hole in , and smaller for
larger . This result has a potentially strong impact on estimates of black
hole production in colliders. In contrast, for , we find the probability
is comparably larger for smaller masses, but , 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
in . For 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
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
In this third paper of the series, we investigate the effects of warm dark
matter with a particle mass of 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 . 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
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
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?
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
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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