2,054 research outputs found
Prevalence of vitamin D deficiency in an inpatient population in the Swiss canton of Basel-Country
AIMS: Vitamin D deficiency remains very common in the general population. Adding to the importance of this issue is the discovery that vitamin D plays a role in many other tissues apart from the bone, including muscle, brain, prostate, breast and colon. In this study, we investigated the prevalence of vitamin D deficiency in a large group of patients hospitalised in the cantonal hospital Basel-Country, and analysed the dependence of serum vitamin D concentrations on gender, time of the year and age. METHODS: We retrospectively analysed anonymised data received from the central laboratory of the cantonal hospital Basel-Country. The pool of data contains values obtained between 2013 and 2017 from 8861 patients aged between 18 and 102 years. If sequential measurements were available from a patient, only the first was used for the analyses. Vitamin D deficiency was defined as a serum concentration of <50 nmol/l and severe deficiency as 75 nmol/l. RESULTS: Mean ± standard deviation serum vitamin D concentration was 52.5 ± 30.5 nmol/l, with women having a higher mean of 55.5 ± 31.5 nmol/l as compared with 48.1 ± 28.6 nmol/l in men (p <10-5). Of the 8861 first measurements taken within the observation period, 4527 (51%) were vitamin D deficient with levels <50 nmol/l, including 1860 (21.0%) with levels <25 nmol/l. There was only a weak positive association of average vitamin D levels with age (p = 0.06). Women reached peak concentrations of 56.9 ± 35.4 nmol/l in the age group 90-102 years, whereas men reached peaks of 50.3 ± 31.9 nmol/l in 50-59-year-olds. Mean autumn and spring concentrations differed less (51.6 ± 29.6 vs 52.7 ± 30.7 nmol/l, respectively, p = 0.38) than mean summer and winter concentrations (57.1 ± 29.5 vs 48.0 ± 31.2 nmol/l, respectively, p 75 nmol/l, only 22.1% of measured values indicated adequate vitamin D levels. This issue should be addressed in order to improve quality of life and reduce medical costs.
Surface-mediated attraction between colloids
We investigate the equilibrium properties of a colloidal solution in contact
with a soft interface. As a result of symmetry breaking, surface effects are
generally prevailing in confined colloidal systems. In this Letter, particular
emphasis is given to surface fluctuations and their consequences on the local
(re)organization of the suspension. It is shown that particles experience a
significant effective interaction in the vicinity of the interface. This
potential of mean force is always attractive, with range controlled by the
surface correlation length. We suggest that, under some circumstances,
surface-induced attraction may have a strong influence on the local particle
distribution
Coping with spatial heterogeneity and temporal variability in resources and risks: Adaptive movement behaviour by a large grazing herbivore.
Movement is a key mean for mobile species to cope with heterogeneous environments. While in herbivorous mammals large-scale migration has been widely investigated, finescale movement responses to local variations in resources and predation risk remain much less studied, especially in savannah environments. We developed a novel approach based on complementary movement metrics (residence time, frequency of visits and regularity of visits) to relate movement patterns of a savannah grazer, the blue wildebeest Connochaetes taurinus , to fine-scale variations in food availability, predation risk and water availability in the Kruger National Park, South Africa. Wildebeests spent more time in grazing lawns where the grass is of higher quality but shorter than in seep zones, where the grass is of lower quality but more abundant. Although the daily distances moved were longer during the wet season compared to the dry season, the daily net displacement was lower, and the residence time higher, indicating a more frequent occurrence of area-concentred searching. In contrast, during the late dry season the foraging sessions were more fragmented and wildebeests moved more frequently between foraging areas. Surprisingly, predation risk appeared to be the second factor, after water availability, influencing movement during the dry season, when resources are limiting and thus expected to influence movement more. Our approach, using complementary analyses of different movement metrics, provided an integrated view of changes in individual movement with varying environmental conditions and predation risk. It makes it possible to highlight the adaptive behavioral decisions made by wildebeest to cope with unpredictable environmental variations and provides insights for population conservation
Statistical mechanics of a colloidal suspension in contact with a fluctuating membrane
Surface effects are generally prevailing in confined colloidal systems. Here
we report on dispersed nanoparticles close to a fluid membrane. Exact results
regarding the static organization are derived for a dilute solution of
non-adhesive colloids. It is shown that thermal fluctuations of the membrane
broaden the density profile, but on average colloids are neither accumulated
nor depleted near the surface. The radial correlation function is also
evaluated, from which we obtain the effective pair-potential between colloids.
This entropically-driven interaction shares many similarities with the familiar
depletion interaction. It is shown to be always attractive with range
controlled by the membrane correlation length. The depth of the potential well
is comparable to the thermal energy, but depends only indirectly upon membrane
rigidity. Consequenses for stability of the suspension are also discussed
Long-term treatment of postmenopausal osteoporotic women with strontium ranelate : results at 10 years
Peer reviewe
Melody processing characterizes functional neuroanatomy in the aging brain
The functional neuroanatomical mechanisms underpinning cognition in the normal older brain remain poorly defined, but have important implications for understanding the neurobiology of aging and the impact of neurodegenerative diseases. Auditory processing is an attractive model system for addressing these issues. Here, we used fMRI of melody processing to investigate auditory pattern processing in normal older individuals. We manipulated the temporal (rhythmic) structure and familiarity of melodies in a passive listening, ‘sparse’ fMRI protocol. A distributed cortico-subcortical network was activated by auditory stimulation compared with silence; and within this network, we identified separable signatures of anisochrony processing in bilateral posterior superior temporal lobes; melodic familiarity in bilateral anterior temporal and inferior frontal cortices; and melodic novelty in bilateral temporal and left parietal cortices. Left planum temporale emerged as a ‘hub’ region functionally partitioned for processing different melody dimensions. Activation of Heschl’s gyrus by auditory stimulation correlated with the integrity of underlying cortical tissue architecture, measured using multi-parameter mapping. Our findings delineate neural substrates for analyzing perceptual and semantic properties of melodies in normal aging. Melody (auditory pattern) processing may be a useful candidate paradigm for assessing cerebral networks in the older brain and potentially, in neurodegenerative diseases of later life
Truncated Levy Random Walks and Generalized Cauchy Processes
A continuous Markovian model for truncated Levy random walks is proposed. It
generalizes the approach developed previously by Lubashevsky et al. Phys. Rev.
E 79, 011110 (2009); 80, 031148 (2009), Eur. Phys. J. B 78, 207 (2010) allowing
for nonlinear friction in wondering particle motion and saturation of the noise
intensity depending on the particle velocity. Both the effects have own reason
to be considered and individually give rise to truncated Levy random walks as
shown in the paper. The nonlinear Langevin equation governing the particle
motion was solved numerically using an order 1.5 strong stochastic Runge-Kutta
method and the obtained numerical data were employed to calculate the geometric
mean of the particle displacement during a certain time interval and to
construct its distribution function. It is demonstrated that the time
dependence of the geometric mean comprises three fragments following one
another as the time scale increases that can be categorized as the ballistic
regime, the Levy type regime (superballistic, quasiballistic, or superdiffusive
one), and the standard motion of Brownian particles. For the intermediate Levy
type part the distribution of the particle displacement is found to be of the
generalized Cauchy form with cutoff. Besides, the properties of the random
walks at hand are shown to be determined mainly by a certain ratio of the
friction coefficient and the noise intensity rather then their characteristics
individually.Comment: 7 pages, 3 figure
Renormalization and Hyperscaling for Self-Avoiding Manifold Models
The renormalizability of the self-avoiding manifold (SAM) Edwards model is
established. We use a new short distance multilocal operator product expansion
(MOPE), which extends methods of local field theories to a large class of
models with non-local singular interactions. This validates the direct
renormalization method introduced before, as well as scaling laws. A new
general hyperscaling relation for the configuration exponent gamma is derived.
Manifolds at the Theta-point, and long range Coulomb interactions are briefly
discussed.Comment: 10 pages + 1 figure, TeX + harvmac & epsf (uuencoded file),
SPhT/93-07
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