1,286 research outputs found
Study made of large amplitude fuel sloshing
Study of resonant oscillations of an ideal fluid in a cylindrical tank is used to obtain a better understanding of fuel sloshing in large liquid booster. More realistic structural design criteria may be formulated when the dynamic response of the liquid in a cylindrical tank can be predicted analytically
An integrated analysis of micro- and macro-habitat features as a tool to detect weather-driven constraints: a case study with cavity nesters
The effects of climate change on animal populations may be shaped by habitat characteristics at both micro- and macro-habitat level, however, empirical studies integrating these two scales of observation are lacking. As analyses of the effects of climate change commonly rely on data from a much larger scale than the microhabitat level organisms are affected at, this mismatch risks hampering progress in developing understanding of the details of the ecological and evolutionary responses of organisms and, ultimately, effective actions to preserve their populations. Cavity nesters, often with a conservation status of concern, are an ideal model because the cavity is a microenvironment potentially different from the macroenvironment but nonetheless inevitably interacting with it. The lesser kestrel (Falco naumanni) is a cavity nester which was until recently classified by as Vulnerable species. Since 2004, for nine years, we collected detailed biotic and abiotic data at both micro- and macro-scales of observation in a kestrel population breeding in the Gela Plain (Italy), a Mediterranean area where high temperatures may reach lethal values for the nest content. We show that macroclimatic features needed to be integrated with both abiotic and biotic factors recorded at a microscale before reliably predicting nest temperatures. Among the nest types used by lesser kestrels, we detected a preferential occupation of the cooler nest types, roof tiles, by early breeders whereas, paradoxically, late breeders nesting with hotter temperatures occupied the overheated nest holes. Not consistent with such a suggested nest selection, the coolest nest type did not host a higher reproductive success than the overheated nests. We discussed our findings in the light of cavity temperatures and nest types deployed within conservation actions assessed by integrating selected factors at different observation scales
Functional characterization of the sea urchin sns chromatin insulator in erythroid cells
Chromatin insulators are regulatory elements that determine domains of genetic functions. We have previously described the characterization of a 265 bp insulator element, termed sns, localized at the 3' end of the early historic H2A gene of the sea urchin Paracentrotus lividus. This sequence contains three cis-acting elements (Box A, Box B, and Box C+T) all needed for the enhancer-blocking activity in both sea urchin and human cells. The goal of this Study was to further characterize the sea urchin sns insulator in the erythroid environment. We employed colony assays in human (K562) and mouse (MEL) erythroid cell lines. We tested the capability of sns to interfere with the communication between the 5HS2 enhancer of the human beta-globin LCR and the gamma-globin promoter. We found that the sns sequence displays directional enhancer-blocking activity. By the use of antibodies against known DNA binding proteins, in electrophoretic mobility shift assays, we demonstrated the binding of the erythroid-specific GATA-1 and the ubiquitous Oct-1 and Sp1 transcription factors. These factors bind to Box A, Box B, and Box C+T, respectively, in both K562 and MEL nuclear extracts. These results may have significant implications for the conservation of insulator function ill evolutionary distant organisms and may prove to be of practical benefit in gene transfer applications for erythroid disorders such as hemoglobinopathies and thalassemias
The spectral element method as an effective tool for solving large scale dynamic soil-structure interaction problems
The spectral element method (SEM) is a powerful numerical technique naturally suited for wave propagation and dynamic soil-structure interaction (DSSI) analyses. A class of SEM has been widely used in the seismological field (local or global seismology) thanks to its capability of providing high accuracy and allowing the implementation of optimized parallel algorithms. We illustrate inthis contribution how the SEM can be effectively used also for the numerical analysis of DSSI problems, with reference to the 3D seismic response of a railway viaduct in Italy. This numerical analysis includes the combined effect of: a) strong lateral variations of soil properties; b) topographic amplification; c) DSSI; d) spatial variation of earthquake ground motion in the structural response. Some hints on the work in progress to effectively handle nonlinear problems with SEM are also given
HYPERPLASIA OF THYMIC GLAND: LEFT VIDEO-ASSISTED THORACOSCOPIC APPROACH
Hyperplasia of thymic gland is a rare benign entity that should be considered in the differential diagnosis of anterior
mediastinal masses in children and young adolescents. We report a case of a patient with a thymic mass, diagnosed occasionally
for respiratory symptoms and treated by video-assisted thoracoscopic surgery. A previously healthy 10 years-old boy
presented to our hospital for retrosternal pain and dyspnea with restriction to daily activities from four months. Diagnostic
imaging was performed, including a chest x-ray and a magnetic resonance imaging, showing a large homogeneous anterosuperior
mediastinal mass, more extended on the left side. The additional laboratory analysis, considered essential for differential
diagnosis with myasthenia gravis and lymphoma, resulted negative. In view of these findings, our patient underwent
to video assisted thoracoscopy with left-sided approach for a total resection of thymus and perithymic fat. The patient made
an excellent recovery without postoperative complications and was discharged from the hospital four days later. Histopathological
examination showed a normal thymic architecture like a true thymic hyperplasia. At follow up, chest x-ray was normal
in absence of pleural and parenchimal alterations. Thoracoscopic thymectomy is a safe technique that allows to achieve the
goal of early thymectomy with the advantages of less invasive procedure
Quaternary marine and continental unconformity-bounded stratigraphic units of the NW Sicily coastal belt
In the coastal sector of NW Sicily, the regional correlation of relevant unconformities recognised within the Quaternary sedimentary successions allowed the mapping of seven unconformitybounded stratigraphic units (UBSUs). The regional unconformities are marine or subaerial erosional surfaces, as well as non-depositional surfaces, locally marked by paleosoils. The erosional surfaces were produced from marine abrasion, surface water overland/ concentrated flow, river erosion, karst solution, mass movement, or wind erosion. The main lithofacies of the Quaternary UBSUs consist of: (a) marine and coastal bioclastic calcarenites, (b) aeolian sandstones, (c) river deposits, (d) colluvial deposits, (e) talus slope deposits, (f) landslide deposits, and (g) chemical carbonates (travertines and speleothems). Quaternary environmental changes, due to tectonics, climate, and sea-level oscillations, are the causes that favoured the development of erosion/deposition processes responsible for the genesis of unconformities and deposits. As a result, through the UBSU map of the NW Sicilian coastal belt, it is possible to: (i) recognise stratigraphic units controlled by tectonic, climatic, and environmental processes (and their interplay) and (ii) detect Quaternary sedimentary evolution
URACHAL CYST: AN UNSPECTED COMPLICATION
The urachus is the remnant of the allantois, which usually becomes obliterated shortly after birth. Urachal remnants
due to an incomplete obliteration of different portion of the urachus are rare, but they need to be treated surgically because
of their potential for infectious complications and malignant degeneration. We present a case report with an unespected postoperative
complication. M.E., a 10 years old boy, came to the Accident and Emergency Department for an acute abdominal
pain, without other symptoms, twice in one year. The blood tests, urine sample and voiding cystourethrogram were normal.
The ultrasound scan showed a thickened urachal duct. After antibiotic and anti-inflammatory therapy for two weeks, we
performed laparoscopic surgery. In the second postoperative day the patient showed abdominal pain and hematuria. An ultrasound
scan and a voiding cystourethrogram showed a leak from the dome of bladder. We performed an open surgery to
close the defect on the bladder’s dome. The patient was discharged in 10th postoperative day. Now he is healthy. Clinically
manifest persistent urachal anomalies are rare, but they carry a risk of recurrent infection and subsequent malignant degeneration.
For these reasons the radical excision of the remnant is suggested. Today, due to the large laparoscopic experience,
all the reports showed that this technique can be used safely, but we have to pay attention to all steps of the procedure. This
case is a paradigmatic situation and it illustrates the importance of a meticulous technique during the excision of urachal
remnant. Indeed even if laparoscopic excision could be safe and effective, it is not free of complication
A Frailty Index based on clinical data to quantify mortality risk in dogs
Frailty is defined as a decline in an organism's physiological reserves resulting in increased vulnerability to stressors. In humans, a single continuous variable, the so-called Frailty Index (FI), can be obtained by multidimensionally assessing the biological complexity of an ageing organism. Here, we evaluate this variability in dogs and compare it to the data available for humans. In dogs, there was a moderate correlation between age and the FI, and the distribution of the FI increased with age. Deficit accumulation was strongly related to mortality. The effect of age, when combined with the FI, was negligible. No sex-related differences were evident. The FI could be considered in epidemiological studies and/or experimental trials to account for the potential confounding effects of the health status of individual dogs. The age-related deficit accumulation reported in dogs is similar to that demonstrated in humans. Therefore, dogs might represent an excellent model for human aging studies
Caudal 'duplication' or 'split' syndrome: Is there a misnomer?
Abstract'Caudal duplication syndrome' was coined to describe the apparent duplication of organs derived from the hindgut, the neural tube and the adjacent mesoderm. Review of the anatomy suggests that the word 'duplication' may be a misnomer. This paper describes the management of 2 girls with caudal duplication syndrome who underwent multistage reconstructive surgery. Both had a large omphalocele and a severe diastasis of the pubic symphysis. The first patient also had an apparent duplication of the vulva, the perineum and the anus to either side of a wide midline. Each vulva contained a urethra, a hemi-clitoris with ipsilateral labium minor, and a hemi-vagina with hemi-uterus. The second child had an infrapubic sequestrated appendico-cecal duplication lying between two hemi-bladders each with ipsilateral ureter and urethra. The everted duplication split the single vulva longitudinally in the midline as far as the fourchette. To each side were a hemi-clitoris, and a hemi-vagina with hemi-uterus and ipsilateral fallopian tube. Analysis of our patients' anatomy and a literature review indicates for the most part 'hemi' organs on either side and suggests that the term 'duplication' is a misnomer such that caudal 'split' syndrome may be a more appropriate title
Super-adsorbent polyacrylate under swelling in water for passive solar control of building envelope
Super-adsorbent polymers have the capacity to immobilize huge quantities of water in the form of hydrogel, thanks to their configuration. A commercial sodium polyacrylate (PA) was analysed as such and at different water uptakes, indicated through the weight ratios PA:H2O. The hydrogels were prepared using different type of water (tap, distilled and deuterated) and characterized by Infrared and Raman spectroscopic analyses, nuclear magnetic resonance experiments, CHN elemental analysis, measurements of thermal conductivity and diffusivity. All the measurements were done in order to assess applications of PA:H2O gels as Thermal Energy Storage systems for improving thermal performances of building envelope through passive solar walls. It has been observed that the behaviour of the hydrogels depends both on temperature and water content. In certain conditions such as low weight ratios, a spontaneous and quick cooling of the hydrogel could be observed. The curves of heat flow and average specific heat (cp) were determined as a function of temperature in order to investigate the states of water in PA hydrogels. When a few water molecules are present, they are mainly and strongly bonded with carboxylate groups. Increasing the amount of water, greater shells of solvation around ionic groups form and water molecules can even interact with neighbouring non-polar hydrocarbon groups. At very high amount of water molecules, they are much more involved into H-bonds among themselves, rather than with PA, so that water pools form into the links of polymeric network. Bulk-like water can freeze and melt. Whatever the amount of water in the hydrogel, its thermal capacity is higher than dry polymer, because the heat can be absorbed by the continuous desorption of water from polymer to bulk-like water (watergel → waterliquid), which can evaporate as temperature approaches 100 °C (watergel → waterliquid → watervapour)
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