153 research outputs found
Wilson loops stability in the gauge/string correspondence
We study the stability of some classical string worldsheet solutions employed
for computing the potential energy between two static fundamental quarks in
confining and non-confining gravity duals. We discuss the fixing of the
diffeomorphism invariance of the string action, its relation with the
fluctuation orientation and the interpretation of the quark mass substraction
worldsheet needed for computing the potential energy in smooth (confining)
gravity background. We consider various dual gravity backgrounds and show by a
numerical analysis the existence of instabilities under linear fluctuations for
classical string embedding solutions having positive length function derivative
. Finally we make a brief discussion of 't Hooft loops in
non-conformal backgrounds.Comment: 34 pages, 36 figures. Reference added. Final version JHEP accepte
Whey protein reduces early life weight gain in mice fed a high-fat diet.
An increasing number of studies indicate that dairy products, including whey protein, alleviate several disorders of the metabolic syndrome. Here, we investigated the effects of whey protein isolate (whey) in mice fed a high-fat diet hypothesising that the metabolic effects of whey would be associated with changes in the gut microbiota composition. Five-week-old male C57BL/6 mice were fed a high-fat diet ad libitum for 14 weeks with the protein source being either whey or casein. Faeces were collected at week 0, 7, and 13 and the fecal microbiota was analysed by denaturing gradient gel electrophoresis analyses of PCR-derived 16S rRNA gene (V3-region) amplicons. At the end of the study, plasma samples were collected and assayed for glucose, insulin and lipids. Whey significantly reduced body weight gain during the first four weeks of the study compared with casein (P<0.001-0.05). Hereafter weight gain was similar resulting in a 15% lower final body weight in the whey group relative to casein (34.0±1.0 g vs. 40.2±1.3 g, P<0.001). Food intake was unaffected by protein source throughout the study period. Fasting insulin was lower in the whey group (P<0.01) and glucose clearance was improved after an oral glucose challenge (P<0.05). Plasma cholesterol was lowered by whey compared to casein (P<0.001). The composition of the fecal microbiota differed between high- and low-fat groups at 13 weeks (P<0.05) whereas no difference was seen between whey and casein. In conclusion, whey initially reduced weight gain in young C57BL/6 mice fed a high-fat diet compared to casein. Although the effect on weight gain ceased, whey alleviated glucose intolerance, improved insulin sensitivity and reduced plasma cholesterol. These findings could not be explained by changes in food intake or gut microbiota composition. Further studies are needed to clarify the mechanisms behind the metabolic effects of whey
A silviculture-oriented spatio-temporal model for germination in Pinus pinea L. in the Spanish Northern Plateau based on a direct seeding experiment
Natural regeneration in Pinus pinea stands
commonly fails throughout the Spanish Northern Plateau
under current intensive regeneration treatments. As a
result, extensive direct seeding is commonly conducted to
guarantee regeneration occurrence. In a period of rationalization
of the resources devoted to forest management,
this kind of techniques may become unaffordable. Given
that the climatic and stand factors driving germination
remain unknown, tools are required to understand the
process and temper the use of direct seeding. In this study,
the spatio-temporal pattern of germination of P. pinea was
modelled with those purposes. The resulting findings will
allow us to (1) determine the main ecological variables
involved in germination in the species and (2) infer adequate
silvicultural alternatives. The modelling approach
focuses on covariates which are readily available to forest
managers. A two-step nonlinear mixed model was fitted to
predict germination occurrence and abundance in P. pinea
under varying climatic, environmental and stand conditions,
based on a germination data set covering a 5-year
period. The results obtained reveal that the process is primarily
driven by climate variables. Favourable conditions
for germination commonly occur in fall although the
optimum window is often narrow and may not occur at all
in some years. At spatial level, it would appear that germination
is facilitated by high stand densities, suggesting
that current felling intensity should be reduced. In accordance
with other studies on P. pinea dispersal, it seems that
denser stands during the regeneration period will reduce
the present dependence on direct seeding
Pere Alberch's developmental morphospaces and the evolution of cognition
In this article we argue for an extension of Pere Alberch's notion of developmental morphospace into the realm of cognition and introduce the notion of cognitive phenotype as a new tool for the evolutionary and developmental study of cognitive abilities
The world health organization multicountry survey on maternal and newborn health: study protocol
<p>Abstract</p> <p>Background</p> <p>Effective interventions to reduce mortality and morbidity in maternal and newborn health already exist. Information about quality and performance of care and the use of critical interventions are useful for shaping improvements in health care and strengthening the contribution of health systems towards the Millennium Development Goals 4 and 5. The near-miss concept and the criterion-based clinical audit are proposed as useful approaches for obtaining such information in maternal and newborn health care. This paper presents the methods of the World Health Organization Multicountry Study in Maternal and Newborn Health. The main objectives of this study are to determine the prevalence of maternal near-miss cases in a worldwide network of health facilities, evaluate the quality of care using the maternal near-miss concept and the criterion-based clinical audit, and develop the near-miss concept in neonatal health.</p> <p>Methods/Design</p> <p>This is a large cross-sectional study being implemented in a worldwide network of health facilities. A total of 370 health facilities from 29 countries will take part in this study and produce nearly 275,000 observations. All women giving birth, all maternal near-miss cases regardless of the gestational age and delivery status and all maternal deaths during the study period comprise the study population. In each health facility, medical records of all eligible women will be reviewed during a data collection period that ranges from two to three months according to the annual number of deliveries.</p> <p>Discussion</p> <p>Implementing the systematic identification of near-miss cases, mapping the use of critical evidence-based interventions and analysing the corresponding indicators are just the initial steps for using the maternal near-miss concept as a tool to improve maternal and newborn health. The findings of projects using approaches similar to those described in this manuscript will be a good starter for a more comprehensive dialogue with governments, professionals and civil societies, health systems or facilities for promoting best practices, improving quality of care and achieving better health for mothers and children.</p
Novel association of severe neonatal encephalopathy and Hirschsprung disease in a male with a duplication at the Xq28 region
<p>Abstract</p> <p>Background</p> <p>Hirschsprung disease (HSCR) is a neurocristopathy characterized by the absence of parasympathetic intrinsic ganglion cells in the submucosal and myenteric plexuses along a variable portion of the intestinal tract. In approximately 18% of the cases HSCR also presents with multiple congenital anomalies including recognized syndromes.</p> <p>Methods</p> <p>A combination of MLPA and microarray data analysis have been undertaken to refine a duplication at the Xq28 region.</p> <p>Results</p> <p>In this study we present a new clinical association of severe neonatal encephalopathy (Lubs syndrome) and HSCR, in a male patient carrying a duplication at the Xq28 region which encompasses the <it>MECP2 </it>and <it>L1CAM </it>genes.</p> <p>Conclusions</p> <p>While the encephalopathy has been traditionally attributed to the <it>MECP2 </it>gene duplication in patients with Lubs syndrome, here we propose that the enteric phenotype in our patient might be due to the dosage variation of the L1CAM protein, together with additional molecular events not identified yet. This would be in agreement with the hypothesis previously forwarded that mutations in <it>L1CAM </it>may be involved in HSCR development in association with a predisposing genetic background.</p
Clinical course of sepsis, severe sepsis, and septic shock in a cohort of infected patients from ten Colombian hospitals
ABSTARCT: Sepsis has several clinical stages, and mortality rates are different for each stage. Our goal was to
establish the evolution and the determinants of the progression of clinical stages, from infection to septic shock,
over the first week, as well as their relationship to 7-day and 28-day mortality
Genetic analysis of the interaction between Allium species and arbuscular mycorrhizal fungi
The response of Alliumcepa, A. roylei, A. fistulosum, and the hybrid A. fistulosum × A. roylei to the arbuscular mycorrhizal fungus (AMF) Glomus intraradices was studied. The genetic basis for response to AMF was analyzed in a tri-hybrid A. cepa × (A. roylei × A. fistulosum) population. Plant response to mycorrhizal symbiosis was expressed as relative mycorrhizal responsiveness (R′) and absolute responsiveness (R). In addition, the average performance (AP) of genotypes under mycorrhizal and non-mycorrhizal conditions was determined. Experiments were executed in 2 years, and comprised clonally propagated plants of each genotype grown in sterile soil, inoculated with G. intraradices or non-inoculated. Results were significantly correlated between both years. Biomass of non-mycorrhizal and mycorrhizal plants was significantly positively correlated. R′ was negatively correlated with biomass of non-mycorrhizal plants and hence unsuitable as a breeding criterion. R and AP were positively correlated with biomass of mycorrhizal and non-mycorrhizal plants. QTLs contributing to mycorrhizal response were located on a linkage map of the A. roylei × A. fistulosum parental genotype. Two QTLs from A. roylei were detected on chromosomes 2 and 3 for R, AP, and biomass of mycorrhizal plants. A QTL from A. fistulosum was detected on linkage group 9 for AP (but not R), biomass of mycorrhizal and non-mycorrhizal plants, and the number of stem-borne roots. Co-segregating QTLs for plant biomass, R and AP indicate that selection for plant biomass also selects for enhanced R and AP. Moreover, our findings suggest that modern onion breeding did not select against the response to AMF, as was suggested before for other cultivated species. Positive correlation between high number of roots, biomass and large response to AMF in close relatives of onion opens prospects to combine these traits for the development of more robust onion cultivars
Successful Interruption of Transmission of Onchocerca volvulus in the Escuintla-Guatemala Focus, Guatemala
Brought to the Americas from Africa by the slave trade, onchocerciasis is present in six countries in Latin America. The disease is caused by a round worm and is transmitted to humans by the bite of an infected black fly. Once in a human, the adult worms produce larvae that circulate through the body, causing itching or even blindness. Ivermectin, a drug that kills the larvae, is delivered by public health authorities in countries where the disease is present. If the larvae are killed, then the disease cannot be transmitted to more people. People living in the Escuintla-Guatemala focus, a region in Guatemala where the disease was common, have been taking ivermectin for many years. The Ministry of Health of Guatemala believes that onchocerciasis is no longer being transmitted in the area. To prove that there is no more transmission of the disease, the authors examined the eyes of residents of the area to see if they could find any evidence of the worms. They also conducted analyses of blood in school children to see if they had ever been exposed to the worm, and they caught thousands of black flies and tested them to see if they were infected. These evaluations found no evidence of transmission of the disease in the Escuintla-Guatemala focus. As a result, local public health authorities can stop giving ivermectin and invest their human resources in other important diseases
Improvement of Aroma in Transgenic Potato As a Consequence of Impairing Tuber Browning
Sensory analysis studies are critical in the development of quality enhanced crops, and may be an important component in the public acceptance of genetically modified foods. It has recently been established that odor preferences are shared between humans and mice, suggesting that odor exploration behavior in mice may be used to predict the effect of odors in humans. We have previously found that mice fed diets supplemented with engineered nonbrowning potatoes (-PPO) consumed more potato than mice fed diets supplemented with wild-type potatoes (WT). This prompted us to explore a possible role of potato odor in mice preference for nonbrowning potatoes. Taking advantage of two well established neuroscience paradigms, the “open field test” and the “nose-poking preference test”, we performed experiments where mice exploration behavior was monitored in preference assays on the basis of olfaction alone. No obvious preference was observed towards -PPO or WT lines when fresh potato samples were tested. However, when oxidized samples were tested, mice consistently investigated -PPO potatoes more times and for longer periods than WT potatoes. Congruently, humans discriminated WT from -PPO samples with a considerably better performance when oxidized samples were tested than when fresh samples were tested in blind olfactory experiments. Notably, even though participants ranked all samples with an intermediate level of pleasantness, there was a general consensus that the -PPO samples had a more intense odor and also evoked the sense-impression of a familiar vegetable more often than the WT samples. Taken together, these findings suggest that our previous observations might be influenced, at least in part, by differential odors that are accentuated among the lines once oxidative deterioration takes place. Additionally, our results suggest that nonbrowning potatoes, in addition to their extended shelf life, maintain their odor quality for longer periods of time than WT potatoes. To our knowledge this is the first report on the use of an animal model applied to the sensory analysis of a transgenic crop
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