948 research outputs found
History friendly simulations for modelling industrial dynamics
simulation, models, industrial dynamics
Analysis of the mass and deformation variation rates over time and their influence on long-term durability for specimens of porous material
In an environment subjected to continuous climatic evolution, the study of the long-term behavior of building materials subject to environmental aggressions becomes an extremely important factor in evaluating the sustainability of these materials over time. The damage due to the aggression of external agents does not only affect the surface of the building but can cause a loss of performance in the mechanical qualities of the material with the worsening of the safety conditions of the entire structure. The velocity of the damage evolution is an interesting item. Here the variation velocity of some parameters characterizing the porous materials subjected to aggressive actions is dealt with. Starting from standard material characterization tests, extending the test times, the rate of variation of the mass and the deformation induced by the absorption of saline solutions in the porous medium and the variation of these speeds over time were evaluated. Hypotheses are formulated on the influence that this speed on the degradation of the material in the short and long time. The results obtained show how long-term aggressive action can cause internal damage with a consequent critical increase in absorption, mass and deformation, phenomena that can induce even severe damage to structural element
About Superluminal motions and Special Relativity: A Discussion of some recent Experiments, and the solution of the Causal Paradoxes
Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay,
Rennes, etc., led to the claim that something seems to travel with a group
velocity larger than the speed c of light in vacuum. Various other experimental
results seem to point in the same direction: For instance, localized wavelet-
type solutions to Maxwell equations have been found, both theoretically and
experimentally, that travel with superluminal speed. [Even muonic and
electronic neutrinos [it has been proposed] might be "tachyons", since their
square mass appears to be negative]. With regard to the first-mentioned
experiments, it was recently claimed by Guenter Nimtz that those results with
evanescent waves (or tunneling photons) imply superluminal signal and impulse
transmission, and therefore violate Einstein causality. In this note we want to
stress that, on the contrary, all such results do not place relativistic
causality in jeopardy, even if they referred to actual tachyonic motions: In
fact, Special Relativity can cope even with superluminal objects and waves. For
instance, it is possible (at least in microphysics) to solve also the known
causal paradoxes, devised for faster than light motion, although this is not
widely recognized yet. Here we show, in detail and rigorously, how to solve the
oldest causal paradox, originally proposed by Tolman, which is the kernel of
many further tachyon paradoxes (like J.Bell's, F.A.E.Pirani's, J.D.Edmonds' and
others'). The key to the solution is a careful application of tachyon
mechanics, as it unambiguously follows from special relativity. At Last, in one
of the two Appendices, we propose how to evaluate the group-velocity in the
case of evanescent waves. [PACS nos.: 03.30.+p; 03.50.De; 41.20.Jb; 73.40.Gk;
84.40.Az; 42.82.Et ]Comment: LaTeX file: 26 pages, with 5 Figures (and two Appendices). The
original version of this paper appeared in the Journal below
Walsh functions: analysis of their properties under Fresnel diffraction
The free-propagation properties of the light field diffracted by an aperture, have been investigated by employing a formalism based on the orthogonal and complete set of Walsh functions. We found an interesting link with the well-known self-imaging phenomenon, which can be used to explain the spatial filtering properties of many optical devices. An experimental result is given in order to illustrate this approach
Direct and indirect costs in the conservative management of undisplaced scaphoid fractures
The scaphoid is the most commonly fractured carpal bone, and preferable treatment of undisplaced fractures is controversial. In order to assess the socio-economic impact of treatment modalities, we analysed the cost of conservative management of 54 undisplaced scaphoid fractures. Global costs amounted to 14.077 Swiss francs (9385 euros) per patient. Direct costs represent only 10% of global costs. No significant correlation was found between costs and timing of diagnosis, hand dominance or complications. Thirty-four percent of patients were able to resume their job with the wrist immobilised without complication, but at an obvious impact on indirect and global costs. If early resumption of professional activities during conservative treatment of undisplaced scaphoid fractures does not impair successful fracture healing, patients should be encouraged to return to work as early as possible, as is routinely done after percutaneous fracture fixation. This will contribute to massively reducing the cost of conservative treatmen
bullous wells syndrome associated with non hodgkin s lymphocytic lymphoma
3/µl; eosinophils 14.3% neutrophils 48%, lymphocytes 31.2%, monocytes 6.5%, basophils 0.2%), total immunoglobulin E (IgE) = 751 IU/ml, C-reactive protein (CRP) 1.25 mg/dl, erythrocyte sedimentation rate (ESR) in the first hour 60 mm; viral markers (Epstein Barr virus, cytomegalovirus, hepatitis A, B and C virus), cryoglobulin, ANCA, LAC, ANA, ENA and anti-DNA antibodies were all negative. Histopathological examination of the lesion on the left leg showed an epidermis characterized by multiple, sometimes confluent vesicles containing serum and eosinophil granulocytes. The underlying papillary dermis was markedly oedematous, with focal and minimal erythrocytic extravasations and an interstitial eosinophil granulocytic infiltrate. The reticular dermis was infiltrated by a large number of prevalently perivascular lymphocytic elements and numerous perivascular and interstitial eosinophil granulocytes, which also extended along the interlobular hypodermal septa and, to a lesser extent, the hypodermic lobules. The reticular dermis also showed some small and isolated flame figures (Fig. 2). The diagnosis of Wells' syndrome was made on the basis of the clinical picture and the histological findings, together with a negative direct immunofluorescence test (5). Having excluded pharmacological, infective, vasculitic and inflammatory causes, the subsequent instrumental and laboratory investigations were aimed at identifying a possible relapse of the patient's previous neoplastic disease. Complete abdominal ultrasonography, chest radiography and colonoscopy were negative, as was a search for tumour markers. The physical examination findings of numerous swollen inguinal and axillary lymph nodes therefore drew our attention to a possible underlying lymphoproliferative disease, and a subsequent lymph node biopsy revealed a picture compatible with a diffuse, small-cell non-Hodgkin's B lymphoma/ B-cell CLL, which was confirmed by a bone marrow biopsy
Evaluation of the weight loss of raw beef cuts vacuum-packaged with two different techniques
In the present study, 25 cuts of shank form adult cattle coming from the same slaughtering batch, were withdrawn just after manual sectioning/deboning, and each divided into two pieces (Prox and Dist) of approximately the same weight, that were vacuum packaged by using two different packaging systems: vacuum chamber machine with a bag material and a thermo-forming packaging machine with top and bottom webs named BAG and THF respectively. The packed cuts were stored at 2-3\ub0C for 20 days. The drip loss was calculated at the end of the storage as the difference between drained weight and net. Internal muscle pH and pH of the exudate present in the package and microbiological analyses (by pooling the samples) were performed at T0 and at the end of the storage. The drip loss, was significantly lower with BAG packaging: this difference was evident after 20 days of storage (average \ub1 STD BAG vs THF = 1.04\ub10.36% vs 1.71\ub10.42%; P<0.01). The values were, in general, low for both the packaging systems, never above 2%. Moreover, shrink bag packages are characterized by better overall pack appearance and less plastic weight per pack. Forming step reduce the thickness of ther-moforming material lowering the mechanical resistance and the barrier to oxygen, on the contrary after shrinking bag materials are thickened. The pH of muscles was stable, although a slight increase was evidenced after 20 (average \ub1 STD BAG vs THF= 5.73\ub10.05 vs 5.78\ub10.09; P<0.01), due to the ageing of meat. The pH of the exudate was equal at T20 (average \ub1 STD BAG vs THF = 5.34\ub10.20 vs 5.33\ub10.17). The drip loss didn\u2019t influence the development of all the microflora; in particular LAB, that represented the main microbial population, showed a gradual increase from T0 (2.20\ub10.41 Log CFU/g) to T20 (average \ub1 STD BAG vs THF= 4.76\ub10.29 Log CFU/g vs 4.75\ub10.0.15 Log CFU/g). No Enterobacteriaceae showed an increase, if compared to the initial counts, due to the prolonged storage and the gradual growth of ephemeral microorganisms, without differences among the two series (Enterobacteriaceae: T0=<1.7 Log CFU/g to T20 average \ub1 STD BAG vs THF = 2.83\ub10.77 Log CFU/g vs 3.09\ub10.0.70 Log CFU/g). In conclusion, the use of the BAG system demonstrated to have an effect in reducing the drip loss of beef cuts during the refrigerated storage, with only slight influence on the other characteristics of raw meat
A new mini-open technique of arthroscopically assisted Latarjet
Background: The aim is to describe a new arthroscopically assisted Latarjet technique.
Methods: We evaluated the clinical and radiological findings of 60 patients with chronic recurrent anterior gleno-humeral instability who underwent, between September 2013 and November 2014, an arthroscopically-assisted Latarjet procedure with double round endobutton fixation. Inclusion criteria were: chronic anterior recurrent instability, Instability Severity Index Score (ISIS) greater than three points, a glenoid bone defect > 15% or a Hill Sachs lesion with concomitant glenoid bone defect > 10%. During surgery the joint capsule and the anterior glenoid labrum were detached. Two drill tunnels perpendicular to the neck of the glenoid were made through a guide. An accessible pilot hole through the glenoid was created to allows the passage of guidewires for coracoid guidance and final fixation onto the anterior glenoid. Through a restricted deltopectoral access a coracoid osteotomy was made. Finally, the graft was prepared, inserted and secured using half-stitches.
Results: The mean follow-up was 32.5 months (range 24\u201332 months). At a mean follow-up, 56 of the 60 subjects claimed a stable shoulder without postoperative complaints, two (3.3%) had an anterior dislocation after new traumatic injury, and two (3.3%) complained of subjective instability. At the latest follow-up, four subjects complained of painful recurrent anterior instability during abduction-external rotation with apprehension. At 1 year, the graft had migrated in one patient (1.7%) and judged not healed and high positioned in another patient (1.7%). Moreover, a glenoid bony gain of 26.3% was recorded. At the latest follow-up, three patients had grade 1 according to Samilson and Prieto classification asymptomatic degenerative changes. Nerve injuries and infections were not detected. None of the 60 patients underwent revision surgery. Healing rate of the graft was 96.7%.
Conclusions: This technique of arthroscopically assisted Latarjet combines mini-open and arthroscopic approach for improving the precision of the bony tunnels in the glenoid and coracoid placement, minimizing any potential risk of neurologic complications. It can be an option in subjects with anterior gleno-humeral instability and glenoid bone defect. Further studies should be performed to confirm our preliminary results
Radon measurements in soil and water in the seismic Friuli area
Radon concentration measurements have been related to seismic occurrence in a number of publications aiming to detect possible pre-seismic or co-seismic variations. Based on these studies, there is evidence that the radon emanation depends on the lithologic and rheologic parameters of the rock, which change in the preparatory stage of the seismic cycle. With the aim of having a better
understanding of these relations, we have set up a station where both radon concentration in soil and deformation are being measured since September 1994. The station is located in the Villanova Cave (468158N, 138168E), 60 m below the surface. The experiment has recently been extended with a second radon station at the Arta Terme thermal baths, where measurements are made in water. A meteorological station controls the principal atmospheric parameters, which could influence radon variation. We present an analysis of the data recorded at the Villanova station, comprising the study of the local seismicity the results of which have been low throughout the recording period. Furthermore, in this study we show some preliminary results regarding the Arta Terme station
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