3,844 research outputs found
Optimal Tradeoff Between Exposed and Hidden Nodes in Large Wireless Networks
Wireless networks equipped with the CSMA protocol are subject to collisions
due to interference. For a given interference range we investigate the tradeoff
between collisions (hidden nodes) and unused capacity (exposed nodes). We show
that the sensing range that maximizes throughput critically depends on the
activation rate of nodes. For infinite line networks, we prove the existence of
a threshold: When the activation rate is below this threshold the optimal
sensing range is small (to maximize spatial reuse). When the activation rate is
above the threshold the optimal sensing range is just large enough to preclude
all collisions. Simulations suggest that this threshold policy extends to more
complex linear and non-linear topologies
Improving risk equalization with constrained regression
State-of-the-art risk equalization models undercompensate some risk groups and overcompensate othe
Systemic lupus during pregnancy with refractory alveolar haemorrhage: recovery following termination of pregnancy
A case of refractory pulmonary hemorrhage in a pregnant 22-year-old with systemic lupus is presented. The clinical difficulty of management of pulmonary haemorrhage and lupus flare during pregnancy are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68549/2/10.1177_096120339700600909.pd
The Fornax Deep Survey with VST. VIII. Connecting the accretion history with the cluster density
This work is based on deep multi-band (g, r, i) data from the Fornax Deep
Survey with VST. We analyse the surface brightness profiles of the 19 bright
ETGs inside the virial radius of the Fornax cluster. The main aim of this work
is to identify signatures of accretion onto galaxies by studying the presence
of outer stellar halos, and understand their nature and occurrence. Our
analysis also provides a new and accurate estimate of the intra-cluster light
inside the virial radius of Fornax. We performed multi-component fits to the
azimuthally averaged surface brightness profiles available for all sample
galaxies. This allows to quantify the relative weight of all components in the
galaxy structure that contribute to the total light. In addition, we derived
the average g-i colours in each component identified by the fit, as well as the
azimuthally averaged g-i colour profiles, to correlate them with the stellar
mass of each galaxy and the location inside the cluster. We find that in the
most massive and reddest ETGs the fraction of light in, probably accreted,
halos is much larger than in the other galaxies. Less-massive galaxies have an
accreted mass fraction lower than 30%, bluer colours and reside in the
low-density regions of the cluster. Inside the virial radius of the cluster,
the total luminosity of the intra-cluster light, compared with the total
luminosity of all cluster members, is about 34%. Inside the Fornax cluster
there is a clear correlation between the amount of accreted material in the
stellar halos of galaxies and the density of the environment in which those
galaxies reside. By comparing this quantity with theoretical predictions and
previous observational estimates, there is a clear indication that the driving
factor for the accretion process is the total stellar mass of the galaxy, in
agreement with the hierarchical accretion scenario.Comment: 18 pages, 10 figures. Accepted for publication in A&
Towards a new classification of early-type galaxies: an integral-field view
In this proceeding we make use of the two-dimensional stellar kinematics of a
representative sample of E and S0 galaxies obtained with the SAURON
integral-field spectrograph to reveal that early-type galaxies appear in two
broad flavours, depending on whether they exhibit clear large-scale rotation or
not. We measure the level of rotation via a new parameter LambdaR and use it as
a basis for a new kinematic classification that separates early-type galaxies
into slow and fast rotators. With the aid of broad-band imaging we will
reinforce this finding by comparing our kinematic results to the photometric
properties of these two classes.Comment: 4 pages, 2 figures, to appear in "Pathways Through an Eclectic
Universe", J. H. Knappen, T. J. Mahoney, and A. Vazedekis (Eds.), ASP Conf.
Ser., 200
Gehechtheid als beïnvloedende factor van gedrags- en psychologische symptomen bij dementie
De laatste jaren wordt in toenemende mate het belang van hechting op oudere leeftijd erkend. Getuigen daarvan zijn vele
onderzoekingen die gebeurden in de voorbije drie decennia. In dit artikel geven we een overzicht van de belangrijkste
resultaten met speciale aandacht voor onderzoek naar hechting en dementie. Studies suggereren dat het aantal
hechtingsfiguren afneemt op oudere leeftijd. Daarentegen wordt de plaats van volwassen kinderen, een overleden partner en
God prominenter. Ook blijkt dat de hechtingsangst daalt naarmate mensen ouder worden, terwijl hechtingsvermijding relatief
stabiel blijft. Veilige gehechtheid is verder positief gerelateerd met groter welzijn en een positievere visie op ouder worden in
vergelijking met meer onveilig gehechte individuen. Onveilige gehechtheid hangt ook samen met een toename van gedragsen
psychologische problemen bij dementerende ouderen. Bij de zorgverlener zijn draaglast en depressiviteit, evenals de wijze
waarop zorg opgenomen wordt en het engagement naar de toekomst toe, verschillend afhankelijk van de hechtingsstijl.
Conform deze bevindingen lijken hechtingsgebaseerde interventies een positief effect op gedrags- en psychologische
symptomen bij dementie te hebben, maar meer onderzoek is hier duidelijk nodig. Tot slot is er nog een weg af te leggen wat
betreft uniformisering en validering van meetmethoden voor hechting op oudere leeftijd
A study of rotating globular clusters - the case of the old, metal-poor globular cluster NGC 4372
Aims: We present the first in-depth study of the kinematic properties and
derive the structural parameters of NGC 4372 based on the fit of a Plummer
profile and a rotating, physical model. We explore the link between internal
rotation to different cluster properties and together with similar studies of
more GCs, we put these in the context of globular cluster formation and
evolution. Methods: We present radial velocities for 131 cluster member stars
measured from high-resolution FLAMES/GIRAFFE observations. Their membership to
the GC is additionally confirmed from precise metallicity estimates. Using this
kinematic data set we build a velocity dispersion profile and a systemic
rotation curve. Additionally, we obtain an elliptical number density profile of
NGC 4372 based on optical images using a MCMC fitting algorithm. From this we
derive the cluster's half-light radius and ellipticity as r_h=3.4'+/-0.04' and
e=0.08+/-0.01. Finally, we give a physical interpretation of the observed
morphological and kinematic properties of this GC by fitting an axisymmetric,
differentially rotating, dynamical model. Results: Our results show that NGC
4372 has an unusually high ratio of rotation amplitude to velocity dispersion
(1.2 vs. 4.5 km/s) for its metallicity. This, however, puts it in line with two
other exceptional, very metal-poor GCs - M 15 and NGC 4590. We also find a mild
flattening of NGC 4372 in the direction of its rotation. Given its old age,
this suggests that the flattening is indeed caused by the systemic rotation
rather than tidal interactions with the Galaxy. Additionally, we estimate the
dynamical mass of the GC M_dyn=2.0+/-0.5 x 10^5 M_Sun based on the dynamical
model, which constrains the mass-to-light ratio of NGC 4372 between 1.4 and 2.3
M_Sun/L_Sun, representative of an old, purely stellar population.Comment: Accepted for publication in A&A, 12 pages, 14 figures, 2 table
The wall shear rate distribution for flow in random sphere packings
The wall shear rate distribution P(gamma) is investigated for pressure-driven
Stokes flow through random arrangements of spheres at packing fractions 0.1 <=
phi <= 0.64. For dense packings, P(gamma) is monotonic and approximately
exponential. As phi --> 0.1, P(gamma) picks up additional structure which
corresponds to the flow around isolated spheres, for which an exact result can
be obtained. A simple expression for the mean wall shear rate is presented,
based on a force-balance argument.Comment: 4 pages, 3 figures, 1 table, RevTeX 4; significantly revised with
significantly extended scop
Case finding of mild cognitive impairment and dementia and subsequent care; results of a cluster RCT in primary care
Purpose Despite a call for earlier diagnosis of dementia, the diagnostic yield of case finding and its impact on the mental health of patients and relatives are unclear. This study assessed the effect of a two-component intervention of case finding and subsequent care on these outcomes. Methods In a cluster RCT we assessed whether education of family physicians (FPs; trial stage 1) resulted in more mild cognitive impairment (MCI) and dementia diagnoses among older persons in whom FPs suspected cognitive decline and whether case finding by a practice nurse and the FP (trial stage 2) added to this number of diagnoses. In addition, we assessed mental health effects of case finding and subsequent care (trial stage 2). FPs of 15 primary care practices (PCPs = clusters) judged the cognitive status of all persons ≤ 65 years. The primary outcome, new MCI and dementia diagnoses by FPs after 12 months as indicated on a list, was assessed among all persons in whom FPs suspected cognitive impairment but without a formal diagnosis of dementia. The secondary outcome, mental health of patients and their relatives, was assessed among persons consenting to participate in trial stage 2. Trial stage 1 consisted of either intervention component 1: training FPs to diagnose MCI and dementia, or control: no training. Trial stage 2 consisted of either intervention component 2: case finding of MCI and dementia and care by a trained nurse and the FP, or control: care as usual. Results Seven PCPs were randomized to the intervention; eight to the control condition. MCI or dementia was diagnosed in 42.3 (138/326) of persons in the intervention, and in 30.5 (98/321) in the control group (estimated difference GEE: 10.8, OR: 1.51, 95-CI 0.60-3.76). Among patients and relatives who consented to stage 2 of the trial (n = 145; 25), there were no differences in mental health between the intervention and control group. Conclusions We found a non-significant increase in the number of new MCI diagnoses. As we cannot exclude a clinically relevant effect, a larger study is warranted to replicate ours. Trial Registration Nederlands Trial Register NTR3389 © 2016 van den Dungen et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
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