251 research outputs found
How do patients' clinical phenotype and the physiological mechanisms of the operations impact the choice of bariatric procedure?
Bariatric surgery is currently the most effective option for the treatment of morbid obesity and its associated comorbidities. Recent clinical and experimental findings have challenged the role of mechanical restriction and caloric malabsorption as the main mechanisms for weight loss and health benefits. Instead, other mechanisms including increased levels of satiety gut hormones, altered gut microbiota, changes in bile acid metabolism, and/or energy expenditure have been proposed as explanations for benefits of bariatric surgery. Beside the standard proximal Roux-en-Y gastric bypass and the biliopancreatic diversion with or without duodenal switch, where parts of the small intestine are excluded from contact with nutrients, resectional techniques like the sleeve gastrectomy (SG) have recently been added to the armory of bariatric surgeons. The variation of weight loss and glycemic control is vast between but also within different bariatric operations. We surveyed members of the Swiss Society for the Study of Morbid Obesity and Metabolic Disorders to assess the extent to which the phenotype of patients influences the choice of bariatric procedure. Swiss bariatric surgeons preferred Roux-en-Y gastric bypass and SG for patients with type 2 diabetes mellitus and patients with a body mass index >50 kg/m(2), which is consistent with the literature. An SG was preferred in patients with a high anesthetic risk or previous laparotomy. The surgeons' own experience was a major determinant as there is little evidence in the literature for this approach. Although trends will come and go, evidence-based medicine requires a rigorous examination of the proof to inform clinical practice
Species-specific differences in follicular antral sizes result from diffusion-based limitations on the thickness of the granulosa cell layer
The size of mature oocytes is similar across mammalian species, yet the size
of ovarian follicles increases with species size, with some ovarian follicles
reaching diameters more than 1000-fold the size of the enclosed oocyte. Here we
show that the different follicular sizes can be explained with diffusion-based
limitations on the thickness of the hormone-secreting granulosa layer. By
analysing published data on human follicular growth and granulosa cell
expansion during follicular maturation we find that the 4-fold increase of the
antral follicle diameter is entirely driven by an increase in the follicular
fluid volume, while the thickness of the surrounding granulosa layer remains
constant at about 45+/-10 mkm. Based on the measured kinetic constants, the
model reveals that the observed fall in the gonadotropin concentration from
peripheral blood circulation to the follicular antrum is a result of
sequestration in the granulosa. The model further shows that as a result of
sequestration, an increased granulosa thickness cannot substantially increase
estradiol production but rather deprives the oocyte from gonadotropins. Larger
animals (with a larger blood volume) require more estradiol as produced by the
ovaries to downregulate FSH-secretion in the pituitary. Larger follicle
diameters result in larger follicle surface areas for constant granulosa layer
thickness. The reported increase in follicular surface area in larger species
indeed correlates linearly both with species mass and with the predicted
increase in estradiol output. In summary, we propose a structural role for the
antrum in that it determines the volume of the granulosa layer and thus the
level of estrogen production.Comment: Mol Hum Repr 201
Acceptance Corrections and Extreme-Independent Models in Relativistic Heavy Ion Collisions
Kopeliovich's suggestion [nucl-th/0306044] to perform nuclear geometry
(Glauber) calculations using different cross sections according to the
experimental configuration is quite different from the standard practice of the
last 20 years and leads to a different nuclear geometry definition for each
experiment. The standard procedure for experimentalists is to perform the
nuclear geometry calculation using the total inelastic N-N cross section, which
results in a common nuclear geometry definition for all experiments. The
incomplete acceptance of individual experiments is taken into account by
correcting the detector response for the probability of measuring zero for an
inelastic collision, which can often be determined experimentally. This clearly
separates experimental issues such as different acceptances from theoretical
issues which should apply in general to all experiments. Extreme-Independent
models are used to illustrate the conditions for which the two methods give
consistent or inconsistent results.Comment: 4 pages, 1 figure, published in Physical Review
Species-specific differences in follicular antral sizes result from diffusion-based limitations on the thickness of the granulosa cell layer
The size of mature oocytes is similar across mammalian species, yet the size of ovarian follicles increases with species size, with some ovarian follicles reaching diameters >1000-fold the size of the enclosed oocyte. Here we show that the different follicular sizes can be explained with diffusion-based limitations on the thickness of the hormone-secreting granulosa layer. By analysing published data on human follicular growth and granulosa cell expansion during follicular maturation we find that the 4-fold increase of the antral follicle diameter is entirely driven by an increase in the follicular fluid volume, while the thickness of the surrounding granulosa layer remains constant at âŒ45 ± 10 ”m. Based on the measured kinetic constants, the model reveals that the observed fall in the gonadotrophin concentration from peripheral blood circulation to the follicular antrum is a result of sequestration in the granulosa. The model further shows that as a result of sequestration, an increased granulosa thickness cannot substantially increase estradiol production but rather deprives the oocyte from gonadotrophins. Larger animals (with a larger blood volume) require more estradiol as produced by the ovaries to down-regulate follicle-stimulating hormone-secretion in the pituitary. Larger follicle diameters result in larger follicle surface areas for constant granulosa layer thickness. The reported increase in the follicular surface area in larger species indeed correlates linearly both with species mass and with the predicted increase in estradiol output. In summary, we propose a structural role for the antrum in that it determines the volume of the granulosa layer and thus the level of estrogen productio
The inverse Laplace transform as the ultimate tool for transverse mass spectra
New high statistics data from the second generation of ultrarelativistic
heavy-ion experiments open up new possibilities in terms of data analysis. To
fully utilize the potential we propose to analyze the -spectra of
hadrons using the inverse Laplace transform. The problems with its inherent
ill-definedness can be overcome and several applications in other fields like
biology, chemistry or optics have already shown its feasability. Moreover, the
method also promises to deliver upper bounds on the total information content
of the spectra, which is of big importance for all other means of analysis.
Here we compute several Laplace inversions from different thermal scenarios,
both analytically and numerically, to test the efficiency of the method.
Especially the case of a two component structure, related to a possible first
order phase transition to a quark gluon plasma, is closer investigated and it
is shown that at least a signal to noise ratio of is necessary to
resolve two individual components.Comment: 13 pages (PostScript, including figures), BNL-NTHES
Baryon Junction Stopping at the SPS and RHIC via HIJING/B
Baryon stopping at the SPS and RHIC energies is calculated by introducing a
new baryon junction mechanism into HIJING. The exchange of a baryon junction,
according to Regge phenomenology, leads to a cosh(y/2) rapidity dependence and
an s^(-1/4) energy dependence of the inclusive baryon cross section. This
baryon junction dynamics also leads naturally to enhanced p_T broadening in pA
and AA together with enhanced mid-rapidity hyperon production.Comment: Proceedings for Quark Matter 97; 4 pages, 1 eps-figur
Proton stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A GeV/c
The shape of proton rapidity distributions is analysed in terms of their
Gaussian components, and the average rapidity loss is determined in order to
estimate the amount of stopping in C+C, d+C, C+Ta and d+Ta collisions at 4.2A
GeV/c. Three Gaussians correspond to the nuclear transparency and describe well
all peripheral and also C+C central collisions. Two-component shape is obtained
in case of d+C and C+Ta central collisions. Finally one Gaussian, found in d+Ta
central collisions, corresponds to the full stopping. The calculated values of
the average rapidity loss support the qualitative relationship between the
number of Gaussian components and the corresponding stopping power. It is also
observed, in central collisions, that the average rapidity loss increases with
the ratio of the number of target and the number of projectile participants.Comment: 9 pages REVTeX, 1 PS figure replaced, to be published in Phys.Rev.
Intermittency and Exotic Channels
It is pointed out that accurate measurements of short-range two-particle
correlations in like-charge and in channels should be
very helpful in determining the origin of the \lq\lq intermittency\rq\rq\
phenomenon observed recently for the like-charge pion pairs.Comment: 5 p., plain tex, preprint T94/078(Saclay), LPTHE 94/58(Orsay
Relativistic Heavy--Ion Collisions in the Dynamical String--Parton Model
We develop and extend the dynamical string parton model. This model, which is
based on the salient features of QCD, uses classical Nambu-Got\=o strings with
the endpoints identified as partons, an invariant string breaking model of the
hadronization process, and interactions described as quark-quark interactions.
In this work, the original model is extended to include a phenomenological
quantization of the mass of the strings, an analytical technique for treating
the incident nucleons as a distribution of string configurations determined by
the experimentally measured structure function, the inclusion of the gluonic
content of the nucleon through the introduction of purely gluonic strings, and
the use of a hard parton-parton interaction taken from perturbative QCD
combined with a phenomenological soft interaction. The limited number of
parameters in the model are adjusted to and -- data. Utilizing
these parameters, the first calculations of the model for -- and
-- collisions are presented and found to be in reasonable agreement with
a broad set of data.Comment: 26 pages of text with 23 Postscript figures placed in tex
Specific Interactions at Cosmic Ray Energies for Extensive Air Showers Experiments
The HIJING and VENUS models of relativistic hadron-nucleus and
nucleus-nucleus collisions are used to study interactions of hadron-hadron,
hadron-nitrogen and nucleus-nitrogen collisions, specific for the extensive air
shower developments initiated by cosmic rays in the atmosphere. The transverse
energy, transverse momenta and spectra of secondary particles as well as their
energy and mass dependence have been investigated in detail. Results are
presented with particular emphasis on the contributions of minijets in HIJING
model and validity of superposition models in this energy range.Comment: latex, revtex, 44 pages, 20 figures, 7 tables , submitted to
Astroparticle Physic
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