689 research outputs found
Criticality of the "critical state" of granular media: Dilatancy angle in the tetris model
The dilatancy angle describes the propensity of a granular medium to dilate
under an applied shear. Using a simple spin model (the ``tetris'' model) which
accounts for geometrical ``frustration'' effects, we study such a dilatancy
angle as a function of density. An exact mapping can be drawn with a directed
percolation process which proves that there exists a critical density
above which the system expands and below which it contracts under shear. When
applied to packings constructed by a random deposition under gravity, the
dilatancy angle is shown to be strongly anisotropic, and it constitutes an
efficient tool to characterize the texture of the medium.Comment: 7 pages RevTex, 8eps figure, to appear in Phys. Rev.
Three-dimensional modeling of lightning-induced electromagnetic pulses on Venus, Jupiter and Saturn
While lightning activity in Venus is still controversial, its existence in
Jupiter and Saturn was first detected by the Voyager missions and later on
confirmed by Cassini and New Horizons optical recordings in the case of
Jupiter, and recently by Cassini on Saturn in 2009. Based on a recently
developed 3D model we investigate the influence of lightning-emitted
electromagnetic pulses (EMP) on the upper atmosphere of Venus, Saturn and
Jupiter. We explore how different lightning properties such as total energy
released and orientation (vertical, horizontal, oblique) can produce
mesospheric transient optical emissions of different shapes, sizes and
intensities. Moreover, we show that the relatively strong background magnetic
field of Saturn can enhance the lightning-induced quasi-electrostatic and
inductive electric field components above 1000 km of altitude producing
stronger transient optical emissions that could be detected from orbital
probes
INNOVATION TRANSFER AND RURAL SMES
The role innovation can play to make enterprises more dynamic and competitive is surely well known. For rural small and medium enterprises (SMEs) this can become a critical issue because they often need financial and technical incentives and support from public and private research institutions in order to make innovation
accessible to them. Yet bridging research and productive dimensions is not always an easy task The cooperation between researchers and rural entrepreneurs can become a rather demoralizing experience for
both parties due to the action of a large number of inadequacies caused not only by financial, technical or organizational factors but also by cultural diversities and different approaches. This paper proposes some considerations matured by the authors while cooperating with some rural SMEs of agro-industrial and agrobusiness
sectors in Central Italy to implement actions of innovation and know how transfer. The experiences reported have been made within the framework of article 15 of the Ministerial Decree (Ministry of University and Research) n. 593/2000 which allows temporary deployment of personnel from research institutions in SMEs. In this paper the authors outline some methodological guidelines developed and adopted to analyze and meet the innovation demand from SMEs involved in innovation transfer processes
Recurrent Non-Hodgkinâs lymphoma in the uterine cervix: a case report and a review of the literature
Background. Lymphomas are a heterogeneous group of malignant lymphoproliferative diseases. As primary localization, the most common histological subtype of female genital lymphomas is a Non-Hodgkin Lymphoma (NHL), the diffuse large B-cell type. However cervical relapse of NHL is a very rare condition (0.3%). Case presentation. A 42-year-old Peruvian woman experienced relapse of NHL with uterine localization. She complained at first of abnormal vaginal bleeding and stranguria. The cervical biopsy performed showed a diffuse large B-cell lymphoma in the uterine cervix. The lack of clinical studies on this topic and its rarity make this type of recurrence very difficult to treat. Conclusions. In case of a woman with vaginal bleeding and history of NHL, a disease relapse should always be considered, and a biopsy should be performed to confirm the diagnosis. © 2023, EDRA S.p.A. All rights reserved
Impact of IFN lambda 3/4 single nucleotide polymorphisms on the cytomegalovirus reactivation in autologous stem cell transplant patients
Cytomegalovirus (CMV) infection represents one of the main cause mortality after Stem Cell Transplantation. Recently, a protective effect of the T allele of rs12979860 IL28B Single Nucleotide Polymorphisms (SNPs) against CMV infection in the allogenic stem cell transplantation was suggested. We investigate whether the rs12979860 IL28B SNP and the relative rs368234815 (IFNλ4) genotype may affect the incidence of active CMV infection in Autologous stem cell transplantation (Auto-SCT) setting. The study included 99 patients who underwent to Auto-SCT. IL28 and IFNÎ4 SNPs were correlated with CMV reactivation along with other clinical and treatment parameters. CMV reactivation by CMV DNAemia was evaluated once a week until day 100 from Auto-SCT. CMV reactivation was documented in 50% (TT-ÎG/ÎG), 35% (CC-TT/TT) and 29.2% (CT-TT/ÎG) of the patients respectively. No differences in CMV copies number were recorded at reactivation between different IL28/IFNλ4 genotypes. The analysis of patients older than 60 years showed a significantly higher incidence of active CMV infection in the TT-ÎG/ÎG (83%) population with respect to CC-TT/TT (21%) and CT-TT/ÎG (40%) patients. Our data suggest a negative role of TT-ÎG/ÎG genotype in the CMV reactivation in Auto-SCT. The exposure to rituximab and the pre-infusion presence of anti CMV IgG also significantly influenced CMV reactivation
An effective numerical modelling strategy for FRCM strengthened curved masonry structures
Fabric Reinforced Cementitious Matrix (FRCM) composites are currently considered a very effective solution for strengthening masonry constructions. However, the mechanical interactions governing the response and the strength of FRCM reinforced masonry structures are very complex, especially in the case of curved structures. Moreover, these interactions involve several interfaces between different materials. Thus, the development of accurate numerical models for curved FRCM reinforced masonry structures comes up against several difficulties, and models too complex for practical applications can be obtained. In addition, several mechanical parameters needed for the calculations are generally inaccessible by conventional experimental tests.
Here, a suitable numerical modelling strategy for FRCM strengthened curved masonry structures is proposed to combine the accuracy in simulating the actual behaviour in terms of stiffness, strength and collapse mechanisms with a reasonable simplicity, making the proposed approach usable also by practitioners, by adopting commercial codes and at a moderate computational effort. The relatively small number of mechanical parameters characterizing the model can be determined by ordinary experimental tests on materials or by literature formulations.
The proposed modelling strategy is validated with respect to experimental data found in literature concerning a FRCM reinforced masonry barrel vault, and then is employed for studying the seismic capacity of the vault through a pushover analysis. A broad sensitivity analysis sheds light on the effect of variations of the mechanical parameters on the predicted overall behaviour, showing the robustness of the results obtainable through the proposed approach concerning inaccuracies in the determination of the parameters often very difficult to determine by ordinary experimental tests on masonry structures.Funding: Financial support from ReLUIS (Italian Department of Civil Protection) and from the Italian Ministry of University and Research (MUR) in the framework of Project PRIN2020 #20209F3A37 is gratefully acknowledged
FAVOR (FAst Variability Optical Registration) -- A Two-telescope Complex for Detection and Investigation of Short Optical Transients
An astronomical complex intended to detect optical transients (OTs) in a wide
field and follow them up with high time resolution investigation is described.Comment: 4 pages, 3 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
Ultrasonographic diagnosis of placenta accreta spectrum (PAS) disorder: Ideation of an ultrasonographic score and correlation with surgical and neonatal outcomes
The objective of this study was to evaluate a novel ultrasonographic scoring system for the diagnosis of PAS and the prediction of maternal and neonatal outcomes. In this retrospective study, 138 patients with at least one previous caesarean section (CS) and placenta previa were included. They were divided into four groups ranging from Group 0 (Non PAS) to Group 3 (Placenta Percreta) according to the histological or surgical confirmation. Their ultrasound examinations during pregnancy were reviewed according to the nine different ultrasound signs reported by the European Working Group on Abnormally Invasive Placenta. For each parameter, 0 to 2 points were assigned. The sum of the points reflects the severity of PAS with a maximum score of 20. The scoring system revealed good performances in evaluation metrics, with an overall accuracy of 94%. In addition to this, patientsâ characteristics and surgical and neonatal outcomes were analyzed with an evidence of higher incidence of complications in severe forms. Our study suggests that antenatal ultrasonographic diagnosis of PAS is feasible with sufficient level of accuracy. This will be important in identifying high-risk patients and implementing preventive strategy
- âŠ