541 research outputs found
Advanced endoscopic imaging for diagnosis of inflammatory bowel diseases : present and future perspectives
Crohn's disease and ulcerative colitis are chronic inflammatory bowel diseases (IBD) causing severe damage of the luminal gastrointestinal tract. Differential diagnosis between both disease entities is sometimes awkward requiring a multifactorial pathway, including clinical and laboratory data, radiological findings, histopathology and endoscopy. Apart from disease diagnosis, endoscopy in IBD plays a major role in prediction of disease severity and extent (i.e. mucosal healing) for tailored patient management and for screening of colitis-associated cancer and its precursor lesions. In this state-of-the-art review, we focus on current applications of endoscopy for diagnosis and surveillance of IBD. Moreover, we will discuss the latest guidelines on surveillance and provide an overview of the most recent developments in the field of endoscopic imaging and IBD
The Stochastic Container Relocation Problem
The Container Relocation Problem (CRP) is concerned with finding a sequence of moves of containers that minimizes the number of relocations needed to retrieve all containers, while respecting a given order of retrieval. However, the assumption of knowing the full retrieval order of containers
is particularly unrealistic in real operations. This paper studies the stochastic CRP (SCRP), which relaxes this assumption. A new multi-stage stochastic model, called the batch model, is introduced, motivated, and compared with an existing model (the online model). The two main contributions are an
optimal algorithm called Pruning-Best-First-Search (PBFS) and a randomized approximate algorithm called PBFS-Approximate with a bounded average error. Both algorithms, applicable in the batch and online models, are based on a new family of lower bounds for which we show some theoretical properties. Moreover, we introduce two new heuristics outperforming the best existing heuristics. Algorithms, bounds and heuristics are tested in an extensive computational section. Finally, based on strong computational evidence, we conjecture the optimality of the “Leveling” heuristic in a special “no information” case, where at any retrieval stage, any of the remaining containers is equally likely to be retrieved next
Effects of Probiotics Supplementation on Risk and Severity of Infections in Athletes: A Systematic Review
The aim of this review was to appraise the literature on the effects of probiotics supplementation on gastrointestinal (GI) and upper respiratory tract infection (URTI) risk and prognosis in athletes. The search was conducted using the following electronic databases: MEDLINE (PubMed); Web of Science; Scopus; and SPORTDiscus (EBSCO). According to the PRISMA guidelines, randomized controlled studies performed on healthy athletes with a note dose of probiotics supplementation were considered. From the 2304 articles found, after eliminating reviews and studies on animals and unhealthy subjects and after screening of titles and abstracts, 403 studies were considered eligible. From these, in accordance with the inclusion and exclusion criteria, 16 studies were selected, ten of which concerned endurance athletes. The majority of the studies reported beneficial effects of probiotics in reducing the risk of developing the examined infections or the severity of related symptoms. However, due to the differences in formulations used and populations analyzed in the available studies, further research is needed in this field to achieve stronger and more specific evidence
Exergames in childhood obesity treatment: A systematic review
In the last decade, active video games (exergames) have been proposed in obesity prevention and treatment as a potential tool to increase physical activity. This review was aimed to assess the possible role of exergames in reducing weight-related outcomes among overweight/obese children and/or adolescents. The databases PubMed, Scopus, Web of Science and SPORTDiscus were interrogated to detect controlled studies involving healthy overweight/obese children and adolescents in interventions based exclusively on exergames. Out of a total of 648 articles found, 10 met the inclusion criteria and were included in the review. The included studies differ for duration, setting and type of intervention, frequency of active game sessions, and outcomes considered. Seven out of ten studies reported better outcomes in children/adolescents involved in the interventions, with significant differences between groups in four, while three studies found better outcomes in control groups. These results suggest a possible positive effect of active video games on weight-related outcomes in obese children and adolescents. However, further research is still needed to define if they can be effectively used in childhood obesity treatment and which may be the most effective approach. The potentiality of the new digital media in this field should be explored
Swimming at the Time of COVID-19: A Cross-Sectional Study among Young Italian Competitive Athletes
During the coronavirus disease 2019 (COVID-19) pandemic, several restriction measures were imposed to control the virus transmission, with important repercussions on different sectors, including sport. This study aimed to explore the effects of the COVID-19 pandemic on Italian competitive swimmers by analyzing how the disease and the restriction measures affected their training. In total, 396 competitive swimmers (mean age 16.0 ± 3.2 years) participated. A questionnaire was used to collect their general information, to assess whether they had had COVID-19 and the number of training days lost due to the disease or to the closure of swimming facilities, and the possible alternative training adopted. Twenty-four (6.1%) participants had had COVID-19 and lost, on average, 32 training days. The closure of facilities caused an interruption in swimming training for about 18% of the participants. The majority of these continued their training, mainly through home-based exercise, but reduced their weekly training time (-8 median hours/week). A positive association was found between regularly adopted weekly training volume and that assumed during pandemic closure (OR 9.433, CI95% 1.644–54.137, p = 0.012), suggesting that the previous level of engagement in sport can represent a predictor of exercise maintenance in challenging situations such as a pandemic. Further studies are needed to identify personal, environmental, and social resources that can help individuals to counteract the negative effects of restriction measures
Are nutrition and physical activity associated with gut microbiota? A pilot study on a sample of healthy young adults
BACKGROUND: The literature shows that gut microbiota composition is related with health, and a lot of individual and outer factors may determine its variability. In particular, nutrition and exercise seem to influence the presence in the gut of the two major bacterial phyla of Firmicutes and Bacteroidetes. STUDY DESIGN: An ongoing cross-sectional investigation is aimed to explore these associations in humans. METHODS: Healthy Caucasian young adults were asked to provide a fecal sample in order to analyze their gut microbiome considering their Body Mass Index (BMI), adherence to Mediterranean diet and Physical Activity (PA) level. RESULTS: A total of 59 participants (49.1% males, mean age 23.1 ± 3.14 years) were enrolled so far. Firmicutes (61.6±14.6) and Bacteroidetes (30.7 ± 13.3) showed the highest relative abundance in fecal samples. The Pearson's analysis showed a significant negative correlation between PA and Firmicutes (r =-0.270, p = 0.03). Linear regression confirmed a significant decrease of this phylum with the increase of PA (R2 = 0.07, p = 0.03). CONCLUSIONS: These preliminary results suggest the association between physical activity and gut microbiota composition in healthy humans
Mediterranean diet, physical activity and gut microbiome composition: A cross-sectional study among healthy young italian adults
Background. This cross-sectional study aimed to explore the microbial composition of the gut and its possible association with the Mediterranean diet (MD) after adjusting for demographic and anthropometric characteristics in a sample of healthy young Italian adults. Methods. Gut microbiota, demographic information, and data on adherence to MD and physical activity (PA) habits were collected in a sample of 140 university students (48.6% males, mean age 22.5 ± 2.9) with a mean body mass index (BMI) of 22.4 ± 2.8 kg/m2 (15.2–33.8) and a mean PA level of 3006.2 ± 2973.6 metabolic equivalent (MET)-minutes/week (148–21,090). Results. A high prevalence of Firmicutes and Bacteroidetes was found in all the fecal samples. Significant dissimilarities in the microbiota composition were found on the basis of MD adherence and PA levels (p = 0.001). At the genus level, Streptococcus and Dorea were highly abundant in overweight/obese individuals, Ruminococcus and Oscillospira in participants with lower adherence to MD, and Lachnobacterium in subjects with low levels of PA (p = 0.001). A significantly higher abundance of Paraprevotella was shown by individuals with lower BMI, lower MD adherence, and lower PA levels (p = 0.001). Conclusions. This study contributes to the characterization of the gut microbiome of healthy humans. The findings suggest the role of diet and PA in determining gut microbiota variability
Cigarette Smoking and Human Gut Microbiota in Healthy Adults: A Systematic Review
The intestinal microbiota is a crucial regulator of human health and disease because of its interactions with the immune system. Tobacco smoke also influences the human ecosystem with implications for disease development. This systematic review aims to analyze the available evidence, until June 2021, on the relationship between traditional and/or electronic cigarette smoking and intestinal microbiota in healthy human adults. Of the 2645 articles published in PubMed, Scopus, and Web of Science, 13 were included in the review. Despite differences in design, quality, and participants’ characteristics, most of the studies reported a reduction in bacterial species diversity, and decreased variability indices in smokers’ fecal samples. At the phylum or genus level, the results are very mixed on bacterial abundance both in smokers and non-smokers with two exceptions. Prevotella spp. appears significantly increased in smokers and former smokers but not in electronic cigarette users, while Proteobacteria showed a progressive increase in Desulfovibrio with the number of pack-years of cigarette (p = 0.001) and an increase in Alphaproteobacteria (p = 0.04) in current versus never smokers. This attempt to systematically characterize the effects of tobacco smoking on the composition of gut microbiota gives new perspectives on future research in smoking cessation and on a new possible use of probiotics to contrast smoke-related dysbiosis
X-ray Luminosity and Absorption Column Fluctuations in the H2O Maser Galaxy NGC 4258 from Weeks to Years
We report monitoring of the 0.3-10 keV spectrum of NGC4258 with XMM over 1.5
years.We als o report reprocessing of an overlapping series of archival Chandra
observations. By including earlier ASCA and SAX observations, we present a new,
nine-year time series of models fit to the X-ray spectrum of NGC4258. Over the
nine years, the photoelectric absorbing column (~10^23 cm^-2) did not vary
detectably, except for a ~40% drop between two ASCA epochs separated by 3 years
and a ~60% rise between two XMM epochs separated by just 5 months. In contrast,
factor of 2-3 changes are seen in absorbed flux on the timescale of years.
These are uncorrelated with changes in absorbing column and indicative of
central engine variability. The most rapid change in luminosity (5-10 keV) that
we detect is ~30% over 19 days. The warped disk, a known source of H2O maser
emission in NGC4258, is believed to cross the line of sight to the central
engine. We propose that the variations in absorbing column arise from
inhomogeneities sweeping across the line of sight in the rotating disk at the
radius where the disk crosses the line of sight. We estimate that the
inhomogeneities are ~10^15 cm in size at the crossing radius of 0.29 pc,
slightly smaller than the expected scale height of the disk. This result thus
provides strong evidence that the warped accretion disk is the absorber. This
is the first direct confirmation that obscuration in type-2 AGN may, in some
cases, arise in thin, warped accretion disks, rather than in geometrically
thick tori. We do not detect Fe Kalpha line emission in any of our XMM spectra.
We do not observe evidence of absorption lines in the XMM or reprocessed
Chandra data.Comment: 36 pages,14 figures. Accepted for publication in Ap
Early in-flight detection of SO<sub>2</sub> via Differential Optical Absorption Spectroscopy: a feasible aviation safety measure to prevent potential encounters with volcanic plumes
Volcanic ash constitutes a risk to aviation, mainly due to its ability to cause jet engines to fail. Other risks include the possibility of abrasion of windshields and potentially serious damage to avionic systems. These hazards have been widely recognized since the early 1980s, when volcanic ash provoked several incidents of engine failure in commercial aircraft. In addition to volcanic ash, volcanic gases also pose a threat. Prolonged and/or cumulative exposure to sulphur dioxide (SO<sub>2</sub>) or sulphuric acid (H<sub>2</sub>SO<sub>4</sub>) aerosols potentially affects e.g. windows, air frame and may cause permanent damage to engines. SO<sub>2</sub> receives most attention among the gas species commonly found in volcanic plumes because its presence above the lower troposphere is a clear proxy for a volcanic cloud and indicates that fine ash could also be present. <br><br> Up to now, remote sensing of SO<sub>2</sub> via Differential Optical Absorption Spectroscopy (DOAS) in the ultraviolet spectral region has been used to measure volcanic clouds from ground based, airborne and satellite platforms. Attention has been given to volcanic emission strength, chemistry inside volcanic clouds and measurement procedures were adapted accordingly. Here we present a set of experimental and model results, highlighting the feasibility of DOAS to be used as an airborne early detection system of SO<sub>2</sub> in two spatial dimensions. In order to prove our new concept, simultaneous airborne and ground-based measurements of the plume of PopocatĂ©petl volcano, Mexico, were conducted in April 2010. The plume extended at an altitude around 5250 m above sea level and was approached and traversed at the same altitude with several forward looking DOAS systems aboard an airplane. These DOAS systems measured SO<sub>2</sub> in the flight direction and at ±40 mrad (2.3°) angles relative to it in both, horizontal and vertical directions. The approaches started at up to 25 km distance to the plume and SO<sub>2</sub> was measured at all times well above the detection limit. In combination with radiative transfer studies, this study indicates that an extended volcanic cloud with a concentration of 10<sup>12</sup> molecules cm<sup>−3</sup> at typical flight levels of 10 km can be detected unambiguously at distances of up to 80 km away. This range provides enough time (approx. 5 min) for pilots to take action to avoid entering a volcanic cloud in the flight path, suggesting that this technique can be used as an effective aid to prevent dangerous aircraft encounters with potentially ash rich volcanic clouds
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