5,511 research outputs found
On the asymptotic behavior of the quasi-static problem for a linear viscoelastic fluid
In this paper we study the quasi-static problem for a viscoelastic fluid by
means of the concept of minimal state. This implies the use of a different free
energy defined in a wider space of data. The existence and uniqueness is proved
in this new space and the asymptotic decay for the problem with non vanishing
supplies is obtained for a large class of memory kernels, including those
presenting an exponential or polynomial decay.Comment: 6 page
The antecedents of e-learning adoption within Italian corporate universities: A comparative case study
The implementation of Information and Communication Technologies (ICT) in business education appears to be influenced by a number of organizational issues, such as culture and technological sophistication. However, extant research has had very little to say about the antecedents that shape the adoption and diffusion of ICT across companies. In order to shed light on the phenomenon under investigation, this paper presents a comparative case study between five Italian companies that have instituted a corporate university. By distinguishing companies in typical cases and deviant cases with regard to the extensive use of e-learning technologies, our findings provide some useful insights about the antecedents that make companies more or less prone to employ the new frontiers of technology in their CUs
An Exploratory Study of Field Failures
Field failures, that is, failures caused by faults that escape the testing
phase leading to failures in the field, are unavoidable. Improving verification
and validation activities before deployment can identify and timely remove many
but not all faults, and users may still experience a number of annoying
problems while using their software systems. This paper investigates the nature
of field failures, to understand to what extent further improving in-house
verification and validation activities can reduce the number of failures in the
field, and frames the need of new approaches that operate in the field. We
report the results of the analysis of the bug reports of five applications
belonging to three different ecosystems, propose a taxonomy of field failures,
and discuss the reasons why failures belonging to the identified classes cannot
be detected at design time but shall be addressed at runtime. We observe that
many faults (70%) are intrinsically hard to detect at design-time
Thermomechanics of damage and fatigue by a phase field model
In the paper we present an isothermal model for describing damage and fatigue
by the use of the Ginzburg-Landau (G-L) equation.
Fatigue produces progressive damage, which is related with a variation of the
internal structure of the material. The G-L equation studies the evolution of
the order parameter, which describes the constitutive arrangement of the system
and, in this framework, the evolution of damage. The thermodynamic coherence of
the model is proved.
In the last part of the work, we extend the results of the paper to a
non-isothermal system, where fatigue contains thermal effects, which increase
the damage of materials.Comment: 21 pages, 4 figure
Locally vascularized pelvic accessory spleen
Il polisplenismo e la milza accessoria sono anomalie congenite generalmente asintomatiche. Riportiamo un raro caso di polisplenismo con milza pelvica ectopica in una donna bianca di 67 anni. Nella pelvi di sinistra all’ecografia transvaginale è stata ritrovata una massa soffice, ben definita, omogenea e vascolarizzata. La paziente è stata quindi sottoposta a valutazione con RM e TC addominale con contrasto: sono state ottenute immagini con aspetto parenchimale simile alla milza. E’ stata eseguita una scintigrafia addominale con albumina umana colloidale radiomarcata con tecnezio sulla regione pelvica con scansioni planari e SPECT. I risultati hanno mostrato la presenza di un’area di captazione del radiofarmaco nella pelvi, mentre la milza è stata normalmente visualizzata. Questi ritrovamenti hanno confermato la presenza di una milza accessoria con una arteria originante dall’aorta ed una vena che si anastomizzava con la vena mesenterica superiore. Alla nostra conoscenza, nella letteratura, esiste solo un caso di vera milza ectopica localmente vascolarizzata nella pelvi.Polysplenism and accessory spleen are congenital, usually asymptomatic anomalies. A rare case of polysplenism with ectopic spleen in pelvis of a 67-year-old, Caucasian female is reported here. A transvaginal ultrasound found a soft well-defined homogeneous and vascularized mass in the left pelvis. Patient underwent MRI evaluation and contrast-CT abdominal scan: images with parenchymal aspect, similar to spleen were obtained. Abdominal scintigraphy with 99mTc-albumin nanocolloid was performed and pelvic region was studied with planar scans and SPECT. The results showed the presence of an uptake area of the radiopharmaceutical in the pelvis, while the spleen was normally visualized. These findings confirmed the presence of an accessory spleen with an artery originated from the aorta and a vein that joined with the superior mesenteric vein. To our knowledge, in the literature, there is just only one case of a true ectopic, locally vascularized spleen in the pelvis
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