377 research outputs found
Prescribed hypocaloric nutrition support for critically-ill adults
Background There are controversies about the amount of calories and the type of nutritional support that should be given to critically‐ill people. Several authors advocate the potential benefits of hypocaloric nutrition support, but the evidence is inconclusive. Objectives To assess the effects of prescribed hypocaloric nutrition support in comparison with standard nutrition support for critically‐ill adults Search methods We searched the Cochrane Central Register of Controlled Trials (CENTRAL, Cochrane Library), MEDLINE, Embase and LILACS (from inception to 20 June 2017) with a specific strategy for each database. We also assessed three websites, conference proceedings and reference lists, and contacted leaders in the field and the pharmaceutical industry for undetected/unpublished studies. There was no restriction by date, language or publication status. Selection criteria We included randomized and quasi‐randomized controlled trials comparing hypocaloric nutrition support to normo‐ or hypercaloric nutrition support or no nutrition support (e.g. fasting) in adults hospitalized in intensive care units (ICUs). Data collection and analysis We used standard methodological procedures expected by Cochrane. We meta‐analysed data for comparisons in which clinical heterogeneity was low. We conducted prespecified subgroup and sensitivity analyses, and post hoc analyses, including meta‐regression. Our primary outcomes were: mortality (death occurred during the ICU and hospital stay, or 28‐ to 30‐day all‐cause mortality); length of stay (days stayed in the ICU and in the hospital); and Infectious complications. Secondary outcomes included: length of mechanical ventilation. We assessed the quality of evidence with GRADE. Main results We identified 15 trials, with a total of 3129 ICU participants from university‐associated hospitals in the USA, Colombia, Saudi Arabia, Canada, Greece, Germany and Iran. There are two ongoing studies. Participants suffered from medical and surgical conditions, with a variety of inclusion criteria. Four studies used parenteral nutrition and nine studies used only enteral nutrition; it was unclear whether the remaining two used parenteral nutrition. Most of them could not achieve the proposed caloric targets, resulting in small differences in the administered calories between intervention and control groups. Most studies were funded by the US government or non‐governmental associations, but three studies received funding from industry. Five studies did not specify their funding sources. The included studies suffered from important clinical and statistical heterogeneity. This heterogeneity did not allow us to report pooled estimates of the primary and secondary outcomes, so we have described them narratively. When comparing hypocaloric nutrition support with a control nutrition support, for hospital mortality (9 studies, 1775 participants), the risk ratios ranged from 0.23 to 5.54; for ICU mortality (4 studies, 1291 participants) the risk ratios ranged from 0.81 to 5.54, and for mortality at 30 days (7 studies, 2611 participants) the risk ratios ranged from 0.79 to 3.00. Most of these estimates included the null value. The quality of the evidence was very low due to unclear or high risk of bias, inconsistency and imprecision. Participants who received hypocaloric nutrition support compared to control nutrition support had a range of mean hospital lengths of stay of 15.70 days lower to 10.70 days higher (10 studies, 1677 participants), a range of mean ICU lengths of stay 11.00 days lower to 5.40 days higher (11 studies, 2942 participants) and a range of mean lengths of mechanical ventilation of 13.20 days lower to 8.36 days higher (12 studies, 3000 participants). The quality of the evidence for this outcome was very low due to unclear or high risk of bias in most studies, inconsistency and imprecision. The risk ratios for infectious complications (10 studies, 2804 participants) of each individual study ranged from 0.54 to 2.54. The quality of the evidence for this outcome was very low due to unclear or high risk of bias, inconsistency and imprecision We were not able to explain the causes of the observed heterogeneity using subgroup and sensitivity analyses or meta‐regression. Authors' conclusions The included studies had substantial clinical heterogeneity. We found very low‐quality evidence about the effects of prescribed hypocaloric nutrition support on mortality in hospital, in the ICU and at 30 days, as well as in length of hospital and ICU stay, infectious complications and the length of mechanical ventilation. For these outcomes there is uncertainty about the effects of prescribed hypocaloric nutrition, since the range of estimates includes both appreciable benefits and harms. Given these limitations, results must be interpreted with caution in the clinical field, considering the unclear balance of the risks and harms of this intervention. Future research addressing the clinical heterogeneity of participants and interventions, study limitations and sample size could clarify the effects of this intervention.Fil: Perman, Mario I. Hospital Italiano; ArgentinaFil: Ciapponi, Agustín. Instituto de Efectividad Clínica y Sanitaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Franco, Juan V.A.. Hospital Italiano; ArgentinaFil: Loudet, Cecilia. Universidad Nacional de La Plata; ArgentinaFil: Crivelli, Adriana. Hospital HIGA San Martín; ArgentinaFil: Garrote, Virginia. Hospital Italiano; ArgentinaFil: Perman, Gastón. Hospital Italiano; Argentin
A comprehensive analysis of the dark matter direct detection experiments in the mirror dark matter framework
Mirror dark matter offers a framework to explain the existing dark matter
direct detection experiments. Here we confront this theory with the most recent
experimental data, paying attention to the various known systematic
uncertainties, in quenching factor, detector resolution, galactic rotational
velocity and velocity dispersion. We perform a detailed analysis of the DAMA
and CoGeNT experiments assuming a negligible channeling fraction and find that
the data can be fully explained within the mirror dark matter framework. We
also show that the mirror dark matter candidate can explain recent data from
the CDMS/Ge, EdelweissII and CRESSTII experiments and we point out ways in
which the theory can be further tested in the near future.Comment: about 30 page
An Improved Limit on Invisible Decays of Positronium
The results of a new search for positronium decays into invisible final
states are reported. Convincing detection of this decay mode would be a strong
evid ence for new physics beyond the Standard Model (SM): for example the
existence of extra--dimensions, of milli-charged particles, of new light gauge
bosons or of mirror particles. Mirror matter could be a relevant dark matter
candidate.
In this paper the setup and the results of a new experiment are presented. In
a collected sample of about orthopositronium decay
s, no evidence for invisible decays in an energy window [0,80] keV was found
and an upper limit on the branching ratio of orthopositronium \invdecay could
be set: \binvdecay<4.2\times 10^{-7} (90% C.L.)
Our results provide a limit on the photon mirror-photon mixing strength
(90% C.L.) and rule out particles lighter
than the electron mass with a fraction of the
electron charge. Furthermore, upper limits on the branching ratios for the
decay of parapositronium (90%
C.L.) and the direct annihilation (90% C.L.) could be set.Comment: 17 pages, 7 figures, added references, fixed limit on millicharged
particles and changed two plots accordingl
Positronium Portal into Hidden Sector: A new Experiment to Search for Mirror Dark Matter
The understanding of the origin of dark matter has great importance for
cosmology and particle physics. Several interesting extensions of the standard
model dealing with solution of this problem motivate the concept of hidden
sectors consisting of SU(3)xSU(2)_LxU(1)_Y singlet fields. Among these models,
the mirror matter model is certainly one of the most interesting. The model
explains the origin of parity violation in weak interactions, it could also
explain the baryon asymmetry of the Universe and provide a natural ground for
the explanation of dark matter. The mirror matter could have a portal to our
world through photon-mirror photon mixing (epsilon). This mixing would lead to
orthopositronium (o-Ps) to mirror orthopositronium oscillations, the
experimental signature of which is the apparently invisible decay of o-Ps. In
this paper, we describe an experiment to search for the decay o-Ps -> invisible
in vacuum by using a pulsed slow positron beam and a massive 4pi BGO crystal
calorimeter. The developed high efficiency positron tagging system, the low
calorimeter energy threshold and high hermiticity allow the expected
sensitivity in mixing strength to be epsilon about 10^-9, which is more than
one order of magnitude below the current Big Bang Nucleosynthesis limit and in
a region of parameter space of great theoretical and phenomenological interest.
The vacuum experiment with such sensitivity is particularly timely in light of
the recent DAMA/LIBRA observations of the annual modulation signal consistent
with a mirror type dark matter interpretation.Comment: 40 pages, 29 Figures 2 Tables v2: Ref. added, Fig. 29 and some text
added to explain idea for backscattering e+ background suppression, corrected
typos v3: minor corrections: Eq 2.1 corrected (6 lines-> 5 lines), Eq.2.17:
two extra "-" signs remove
Infraestructura y competitividad en la Iniciativa de la Franja y la Ruta: implicaciones geoeconómicas en el caso del puente HZM
This work addresses the importance of infrastructure projects within the Belt and Road Initiative. Specifically, it focuses on the case of the hzm Bridge as one of the most important facilities with a direct impact on the commercial activity of the region. From this, we seek to determine the commercial advantages of the construction of this bridge for the People’s Republic of China (PRC), since this engineering project is an extension of the Belt and Road Initiative that brings great geoeconomic advantages for this country with respect the rest of the world and its special administration regions.El presente trabajo trata de la importancia que la infraestructura tiene dentro de la Iniciativa de la Franja y la Ruta. En específico, se enfoca en el caso del puente HZM como una de las más importantes obras que tienen un impacto en la actividad comercial de la región. Partiendo de esto, se busca determinar las ventajas a nivel comercial que la construcción este puente implica para la República Popular China (RPCH), en tanto que la construcción de este es una extensión de dicha iniciativa que trae grandes ventajas geoeconómicas a la rpch hacia el exterior y también con respecto a sus regiones de administración especial
Influence of ligand structure and molecular geometry on the properties of d6 polypyridinic transition metal complexes
Different strategies to improve the excited state properties of polypyridinic complexes by varying ligand structure and molecular geometry are described. Bidentate and tetradentate ligands based on fragments as dipyrido[3,2-a:2′,3′-c]phenazine, dppz, and pyrazino[2,3-f][1,10]-phenanthroline, ppl, have been used. Quinonic residues were fused to these basic units to improve acceptor properties. Photophysical studies were performed in order to test theoretical predictions
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