559 research outputs found

    Fractional queues with catastrophes and their transient behaviour

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    Starting from the definition of fractional M/M/1 queue given in the reference by Cahoy et al. in 2015 and M/M/1 queue with catastrophes given in the reference by Di Crescenzo et al. in 2003, we define and study a fractional M/M/1 queue with catastrophes. In particular, we focus our attention on the transient behaviour, in which the time-change plays a key role. We first specify the conditions for the global uniqueness of solutions of the corresponding linear fractional differential problem. Then, we provide an alternative expression for the transient distribution of the fractional M/M/1 model, the state probabilities for the fractional queue with catastrophes, the distributions of the busy period for fractional queues without and with catastrophes and, finally, the distribution of the time of the first occurrence of a catastrophe

    The Plio-Quaternary uplift of the Apennine Chain: new data from the analysis of topography and river valleys in Central Italy

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    This study aimed at the reconstruction of magnitude and timing of uplift of a wide sector of the Central Apennines (Italy) by means of morphometric and morphostructural analyses. In the internal portion of the chain (where stratigraphic and geomorphological markers of past sea-level positions are lacking) the study was based on analysis of erosional landforms and river valleys. A large-scale topographic analysis was performed, processing 90-m and 230-m DEMs. The spatial distribution of several morphometric parameters, together with characteristic wavelengths of relief, allowed the distinction of three main regions affected by different cumulative surface uplift and tectonic/erosional fragmentation: a Peri-Tyrrhenian Belt; an Axial Belt; a Peri-Adriatic Belt. Particular attention was devoted to fluvial landforms, with analysis of longitudinal profiles and geometric pattern of the main stream-trunks and their relations with major structures. Major differences occur between the Tyrrhenian and Adriatic valley systems, the former being generally longitudinal and showing overall concave-upward longitudinal profiles, whereas the latter are generally transverse and possess less regular longitudinal profiles. Topographic features and river valleys architecture seem related to different styles and amounts of uplift in the three Belts. Within the study area, a narrower coast to coast transect (Gaeta-Vasto Transect, GVT) was investigated in detail, devoting particular attention to its axial sector, lying around the Apennines main divide (main divide area: MDA), and a possible scheme of the Quaternary surface uplift inside this transect was proposed. In the MDA, the main stages of landscape evolution and river network organization were reconstructed by analysis of paleosurfaces coupled with analysis of relic and present-day hydrographic network. This allowed recognition of a major phase of surface uplift (exceeding 1500 m in the Meta-Mainarde massif) occurred in response to thrusting during the Pliocene, whereas for the Quaternary uplift a minimum value around 400 m was estimated. Our study suggests that, during the Quaternary and in the GVT, the Peri-Tyrrhenian Belt suffered a subdued uplift operating over small wavelengths (10-15 km), while Axial and Peri- Adriatic Belts were subject to a stronger and long-wavelength (90 km) surface uplift, with maximum values (about 700 m) shifted NE of the Axial Belt and tapering to zero towards the Adriatic coast. The reconstructed pattern of uplift is coherent with the topographic properties of the three Belts and with the observed drainage features

    Factors influencing the prevalence of animal cruelty during adolescence

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    Adolescents’ interactions with animals are of increasing interest and their beneficial developmental outcomes are well known. However, negative interactions such as perpetrating cruelty toward animals during childhood and adolescence have been related with child abuse, domestic violence, and later interpersonal violence. Cruelty toward animals by adolescents has been reported predominately in criminal and clinical samples, and links have been made between animal cruelty and interpersonal violence. However, studies often lack a clear definition of animal cruelty and the animal involved. The present study addresses methodological shortcomings by providing a clear definition of the cruelty acts and the animals involved and the time frame within which cruelty acts have been taken place. Therefore, we investigated the prevalence of animal cruelty of 979 British adolescents (419 male, 497 female, Mage = 15.1 ± 1.57 years) by means of a survey questionnaire administered in school. Animal cruelty was investigated encompassing deliberate and nondeliberate cruelty acts, a clear definition of the target animals was included and a time frame was provided. Furthermore, acceptability of animal cruelty, engaging in antisocial behavior, and family affluence were investigated. Results show high reliabilities for the measures applied. Exploratory factor analysis reveals different types of animal cruelty. Gender differences were observed for deliberate and accidental cruelty acts, with boys reporting higher levels than girls. Younger adolescents reported higher accidental cruelty acts than older ones. Acceptance of animal cruelty played a significant role in predicting animal cruelty, together with antisocial behaviors and place of living. The present study shows for the first time the importance of distinguishing between different types of animal cruelty and defining the animals involved.PostprintPeer reviewe

    Isolated human pulmonary artery structure and function pre‐ and post‐cardiopulmonary bypass surgery

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    Background: Pulmonary dysfunction is a known complication after cardiac surgery using cardiopulmonary bypass, ranging from subclinical functional changes to prolonged postoperative ventilation, acute lung injury, and acute respiratory distress syndrome. Whether human pulmonary arterial function is compromised is unknown. The aim of the present study was to compare the structure and function of isolated and cannulated human pulmonary arteries obtained from lung biopsies after the chest was opened (pre–cardiopulmonary bypass) to those obtained at the end of cardiopulmonary bypass (post–cardiopulmonary bypass) from patients undergoing coronary artery bypass graft surgery. Methods and Results: Pre‐ and post–cardiopulmonary bypass lung biopsies were received from 12 patients undergoing elective surgery. Intralobular small arteries were dissected, cannulated, pressurized, and imaged using confocal microscopy. Functionally, the thromboxane mimetic U46619 produced concentration‐dependent vasoconstriction in 100% and 75% of pre‐ and post–cardiopulmonary bypass arteries, respectively. The endothelium‐dependent agonist bradykinin stimulated vasodilation in 45% and 33% of arteries pre‐ and post–cardiopulmonary bypass, respectively. Structurally, in most arteries smooth muscle cells aligned circumferentially; live cell viability revealed that although 100% of smooth muscle and 90% of endothelial cells from pre–cardiopulmonary bypass biopsies had intact membranes and were considered viable, only 60% and 58%, respectively, were viable from post–cardiopulmonary bypass biopsies. Conclusions: We successfully investigated isolated pulmonary artery structure and function in fresh lung biopsies from patients undergoing heart surgery. Pulmonary artery contractile tone and endothelium‐dependent dilation were significantly reduced in post–cardiopulmonary bypass biopsies. The decreased functional responses were associated with reduced cell viability. Clinical Trial Registration: URL: http://www.isrctn.com/ISRCTN34428459. Unique identifier: ISRCTN 34428459.</p

    Imatinib interferes with survival of multi drug resistant Kaposi’s sarcoma cells.

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    Multi drug resistance (MDR) is defined as the ability of tumor cells to become resistant to unrelated drugs. Tyrosine kinase inhibitor imatinib has been demonstrated to be effective in the treatment of certain tumors. In particular, imatinib inhibits Bcr-Abl kinase activity, c-kit and the phosphorylation of platelet-derived growth factor (PDGF) receptors. In this work, we show that imatinib inhibits PDGF phosphorylation not only in wt Kaposi sarcoma (KS) but also in multi drug resistant KS cells. This was associated with an increased apoptosis in wt cells and an increased autophagy in MDR-KS cells. These data add new insights to the possible use of imatinib in the overcoming of MDR in KS cells

    Vinorelbine-based chemotherapy in hormone refractory prostate cancer

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    Background: No consensus exists regarding further therapy for the management of hormone-refractory prostate cancer. In this phase II study, the combination of Vinorelbine with 5-Fluorouracil and folinic acid (FLN regimen) was evaluated in patients with progressive or resistant disease after hormone therapy. Patients and Methods: Thirty-four patients were treated with Vinorelbine at a dose of 20 mg/m 2 intravenously (i.v.) on days 1 and 3, folinic acid (FA), 100 mg/m 2 i.v. and 5-Fluorouracil (5-FU), 350 mg/m 2 i.v. as a short infusion on days 1 to 3. The therapy was given in an out-patient setting, every 3 weeks. Results: All of the 34 eligible patients were evaluable for toxicity and 30 for activity. A total of 127 cycles was administered (91% at full dose). Among the 15 patients with measurable disease, four had a partial response (26.6%; C.I. 95%, 28.3% to 65.7%) and four achieved stable disease. In 14 patients (47%) a clinical benefit was documented. Six out of 15 patients with bone-only involvement had stable disease (40%). The median duration of stabilization and partial response was 16 weeks (range 4-24 weeks). The most common toxicity was hematological: Grade 4 (NCI-CTC scale) in five patients at re-cycle. Other toxicities were of low incidence and easy to manage. Conclusion: The encouraging results obtained with the FLN regimen in terms of clinical benefit and its predictable and manageable toxicity support the palliative role of this chemotherapeutic strategy in hormone-refractory prostate patients

    Fluency development in second language teaching

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    viii, 102 leaves ; 29 cm.Al though students may spend several years (up to 12 years) in learning a second language, we must recognize the fact that a great number of these students are still not proficient and fluent in speaking the foreign language. Since the actual trend in learning second languages is directed toward the development of oral proficiency, and since oral fluency is one of its components, students need to speak with a certain degree of fluency in order to demonstrate their oral proficiency. The purpose of this study was to describe factors or conditions which contributed to the development of oral fluency in selected, fluent grade 12 students. The first step was to define oral fluency, followed by the development of an appropriate device to evaluate it. The selected fluent students were interviewed. The interviews were later analyzed in order to determine the preponderant factors or conditions contributing to oral fluency, and to find the answers to the following questions: 1. Is there a pattern or are there similar factors/conditions among the students that have contributed to their oral fluency development? 2. What are specific ways to promote oral fluency development in a second language? The main findings of this study were that oral fluency was acquired as a result of several factors: students who are positive and self-motivated, a learning experience which has been positive and enjoyable for the students, parents as well as teachers who have been positive and supportive, teachers who were proficient in the second language, and its having taken place within a second language immersion learning environment. This study provides a list of requirements and factors that will help to promote oral fluency in a second language

    Repurposing of plasminogen: An orphan medicinal product suitable for SARS-CoV-2 inhalable therapeutics

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    The SARS-CoV-2 infection is associated with pulmonary coagulopathy, which determines the deposition of fibrin in the air spaces and lung parenchyma. The resulting lung lesions compromise patient pulmonary function and increase mortality, or end in permanent lung damage for those who have recovered from the COVID-19 disease. Therefore, local pulmonary fibrinolysis can be efficacious in degrading pre-existing fibrin clots and reducing the conversion of lung lesions into lasting scars. Plasminogen is considered a key player in fibrinolysis processes, and in view of a bench-to-bedside translation, we focused on the aerosolization of an orphan medicinal product (OMP) for ligneous conjunctivitis: human plasminogen (PLG-OMP) eye drops. As such, the sterile and preservative-free solution guarantees the pharmaceutical quality of GMP production and meets the Ph. Eur. requirements of liquid preparations for nebulization. PLG-OMP aerosolization was evaluated both from technological and stability viewpoints, after being submitted to either jet or ultrasonic nebulization. Jet nebulization resulted in a more efficient delivery of an aerosol suitable for pulmonary deposition. The biochemical investigation highlighted substantial protein integrity maintenance with the percentage of native plasminogen band &gt; 90%, in accordance with the quality specifications of PLG-OMP. In a coherent way, the specific activity of plasminogen is maintained within the range 4.8–5.6 IU/mg (PLG-OMP pre-nebulization: 5.0 IU/mg). This is the first study that focuses on the technological and biochemical aspects of aerosolized plasminogen, which could affect both treatment efficacy and clinical dosage delivery. Increasing evidence for the need of local fibrinolytic therapy could merge with the availability of PLG-OMP as an easy handling solution, readily aerosolizable for a fast translation into an extended clinical efficacy assessment in COVID-19 patients
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