3,332 research outputs found
Order statistics and heavy-tail distributions for planetary perturbations on Oort cloud comets
This paper tackles important aspects of comets dynamics from a statistical
point of view. Existing methodology uses numerical integration for computing
planetary perturbations for simulating such dynamics. This operation is highly
computational. It is reasonable to wonder whenever statistical simulation of
the perturbations can be much more easy to handle. The first step for answering
such a question is to provide a statistical study of these perturbations in
order to catch their main features. The statistical tools used are order
statistics and heavy tail distributions. The study carried out indicated a
general pattern exhibited by the perturbations around the orbits of the
important planet. These characteristics were validated through statistical
testing and a theoretical study based on Opik theory.Comment: 9 pages, 12 figures, submitted for publication in Astronomy and
Astrophysic
Visual-cortical enhancement by acoustic distractors: The effects of endogenous spatial attention and visual working memory load
Past work has shown that when a peripheral sound captures our attention, it activates the contralateral visual cortex as revealed by an event-related potential component labelled the auditory-evoked contralateral occipital positivity (ACOP). This cross-modal activation of the visual cortex has been observed even when the sounds were not relevant to the ongoing task (visual or auditory), suggesting that peripheral sounds automatically activate the visual cortex. However, it is unclear whether top-down factors such as visual working memory (VWM) load and endogenous attention, which modulate the impact of task-irrelevant information, may modulate this spatially-specific component. Here, we asked participants to perform a lateralized VWM task (change detection), whose performance is supported by both endogenous spatial attention and VWM storage. A peripheral sound that was unrelated to the ongoing task was delivered during the retention interval. The amplitude of sound-elicited ACOP was analyzed as a function of the spatial correspondence with the cued hemifield, and of the memory array set-size. The typical ACOP modulation was observed over parieto-occipital sites in the 280â500 ms time window after sound onset. Its amplitude was not affected by VWM load but was modulated when the location of the sound did not correspond to the hemifield (right or left) that was cued for the change detection task. Our results suggest that sound-elicited activation of visual cortices, as reflected in the ACOP modulation, is unaffected by visual working memory load. However, endogenous spatial attention affects the ACOP, challenging the hypothesis that it reflects an automatic process
First Results on the Removal of Emerging Micropollutants from Municipal Centrate by Microalgae
The results of a first campaign of sampling and analyses of emerging micropollutants in the influent (municipal centrate) and effluent of a pilot MBP raceway are reported. The algal population was chiefly made of Chlorella spp. and the pilot worked satisfactorily for the removal of nitrogen. 14 emerging micropollutants were analysed. Average removal efficiencies exceeding 80 % were observed for diclofenac, lamotrigine, ketoprofene, clarithromycin. For such compounds the variability of removal efficiency was also reduced, with respect to the other tested molecules, and was particularly low for diclofenac and lamotrigine. Removal efficiencies over 50 % were measured for azithromycin, metoprolol and irbesartan but with strong variability. Lower removal efficiencies were observed for amisulpride and 5-methylbenzotriazole, while for the remaining compounds the concentrations in the effluent were higher than in the influent
Three-dimensional CAD/CAM reconstruction of the iliac bone following DCIA composite flap harvest
This article reports a new technique to restore iliac bone integrity with a customized titanium device designed by CAD/CAM, in patients undergoing deep circumflex iliac artery (DCIA) composite flap harvest. Eight consecutive patients who underwent the repair of major head and neck defects with DCIA flaps were enrolled retrospectively. Computed tomography scans of the pelvis were obtained preoperatively. Starting from DICOM data, each personalized device was designed using modelling software and was finally made by additive manufacturing using a laser sintering machine. After surgery, the patients were followed up at 3-month intervals to evaluate the incidence of complications and the long-term outcome at the donor site. A subcutaneous seroma developed in one patient and an inguinal skin burn occurred in another. At a median follow-up of 12 months, the patients did not report pain, or any gait or sensory disturbance at the donor site. There was no occurrence of bulging, herniation, or instability or inflammation near the device for the entire follow-up duration. All patients were satisfied with the aesthetic result. In conclusion, reconstruction of the iliac bone with a customized device is safe and well tolerated. We recommend use of this device in patients deemed at high risk of herniation. Further studies are needed to confirm the stability of the device in the long term
Effect of a multistrain probiotic (LactofloreneÂź Plus) on inflammatory parameters and microbiota composition in subjects with stress-related symptoms
Stress affects the immune system and intestinal microbiota composition and can lead to imbalance between pro- and anti-inflammatory cytokines or to uncontrolled production of cytokines. The effect of emotional stress on secretory IgA levels also indicates that stress decreases mucosal integrity. Our aim was to evaluate whether a probiotic product (LactofloreneŸ Plus) can prevent alterations in the immune response associated with self-reported stress and microbiota composition. Healthy adult volunteers who self-reported psychological stress were enrolled and randomised into a placebo and a probiotic group. Salivary stress markers (α-amylase, cortisol, chromogranin A) and immunological parameters (sIgA, NK cell activity, IL-8, IL-10, TNF-α) in feces and the composition of intestinal microbiota were evaluated. Administration of the product did not exert a direct effect on the salivary stress markers or NK cell activity but did reduce abdominal pain and increase faecal IgA and IL-10 levels. The probiotic product induced a moderate increase in Bifidobacterium and Lactobacillus spp., as expected, and in Faecalibacterium spp., and decreased the size of the Dialister spp. and Escherichia and Shigella populations. Administration of the product helped protect the mucosal barrier by supporting the number of short-chain fatty acid producers and decreasing the load of potentially harmful bacteria, thus reducing intestinal inflammation and abdominal discomfort. ClinicalTrials.gov: NCT03234452
Simbol-X Hard X-ray Focusing Mirrors: Results Obtained During the Phase A Study
Simbol-X will push grazing incidence imaging up to 80 keV, providing a strong
improvement both in sensitivity and angular resolution compared to all
instruments that have operated so far above 10 keV. The superb hard X-ray
imaging capability will be guaranteed by a mirror module of 100 electroformed
Nickel shells with a multilayer reflecting coating. Here we will describe the
technogical development and solutions adopted for the fabrication of the mirror
module, that must guarantee an Half Energy Width (HEW) better than 20 arcsec
from 0.5 up to 30 keV and a goal of 40 arcsec at 60 keV. During the phase A,
terminated at the end of 2008, we have developed three engineering models with
two, two and three shells, respectively. The most critical aspects in the
development of the Simbol-X mirrors are i) the production of the 100 mandrels
with very good surface quality within the timeline of the mission; ii) the
replication of shells that must be very thin (a factor of 2 thinner than those
of XMM-Newton) and still have very good image quality up to 80 keV; iii) the
development of an integration process that allows us to integrate these very
thin mirrors maintaining their intrinsic good image quality. The Phase A study
has shown that we can fabricate the mandrels with the needed quality and that
we have developed a valid integration process. The shells that we have produced
so far have a quite good image quality, e.g. HEW <~30 arcsec at 30 keV, and
effective area. However, we still need to make some improvements to reach the
requirements. We will briefly present these results and discuss the possible
improvements that we will investigate during phase B.Comment: 6 pages, 3 figures, invited talk at the conference "2nd International
Simbol-X Symposium", Paris, 2-5 december, 200
Free flap head and neck reconstruction in the elderly: What is the impact on quality of life?
Morphofunctional reconstruction is a pivotal aspect in the surgery of head and neck neoplasms: Nowadays, microvascular free flap surgery represents the gold standard. In choosing the surgical technique, the effects on residual quality of life, especially in elderly people, usually considered more fragile and so often excluded from microsurgical procedures, must be taken into account. This multicentre study evaluated the quality of life index in patients more than 75 years of age and who underwent to head and neck microsurgical reconstruction. Data from patients aged > 75 years at the time of major head and neck reconstruction conducted with free flaps between 1 January 2005 and 30 June 2015 were analysed retrospectively. We administered the Italian version of Quality of Life questionnaire SF-36, at least 24 months after surgery. Results were compared to those for the general Italian population of the same age. We enrolled 39 patients with an average age of 80.6 years. The results did not differ significantly from the reference population. The international literature has already shown that chronologic age is not a valid parameter to determine the surgical treatment modality. Even considering the quality of residual life, our study supports the indication for free-flap reconstruction of head and neck defects in the elderly, confirming its effectiveness in this population
Migration of Jupiter-family comets and resonant asteroids to near-Earth space
We estimated the rate of comet and asteroid collisions with the terrestrial
planets by calculating the orbits of 13000 Jupiter-crossing objects (JCOs) and
1300 resonant asteroids and computing the probabilities of collisions based on
random-phase approximations and the orbital elements sampled with a 500 yr
step. The Bulirsh-Stoer and a symplectic orbit integrator gave similar results
for orbital evolution, but sometimes give different collision probabilities
with the Sun. A small fraction of former JCOs reached orbits with aphelia
inside Jupiter's orbit, and some reached Apollo orbits with semi-major axes
less than 2 AU, Aten orbits, and inner-Earth orbits (with aphelia less than
0.983 AU) and remained there for millions of years. Though less than 0.1% of
the total, these objects were responsible for most of the collision probability
of former JCOs with Earth and Venus. Some Jupiter-family comets can reach
inclinations i>90 deg. We conclude that a significant fraction of near-Earth
objects could be extinct comets that came from the trans-Neptunian region.Comment: Proc. of the international conference "New trends in astrodynamics
and applications" (20-22 January 2003, University of Maryland, College Park
Active TB screening among homeless people attending soup kitchens in Verona (Italy)
BACKGROUND: The hard-to-reach populations, including the homeless, are particularly vulnerable to the development of active tuberculosis. According to the World Health Organization, tuberculosis rates among the homeless in industrialized Countries are up to 20 times higher if compared with the general population, representing a relevant public health problem. The aim of our study was to describe the results of an active tuberculosis screening applied in order to find out suspected active TB cases among the homeless in Verona.METHODS: As part of a partnership between the non-profit association Medici per la Pace and one of the Local Health Units of Veneto Region (ULSS 9 Scaligera) in 2018, a tuberculosis screening, based on thoracic radiographs, was offered to the homeless guests of two Verona's soup kitchens.RESULT: The studied population included 139 people, and three cases of suspected active tuberculosis, all in males, were observed. Among these, two received a diagnostic confirmation of active tuberculosis (a prevalence of 1.44% - CI: 0,17 - 5,1). Moreover, radiographic patterns of tuberculosis aftermaths were found in six additional subjects.CONCLUSION: Interventions specifically dedicated to hard-to-reach populations, can be useful in identifying tuberculosis active cases and controlling the disease in low tuberculosis burden countries. In particular, the active research of subjects, the screening carried out with mobile X-ray, and also the constant caring of the patients with active disease, could be the right method to keep under control this relevant public health problem
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