1,016 research outputs found

    Dispersion relations for the time-fractional Cattaneo-Maxwell heat equation

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    In this paper, after a brief review of the general theory of dispersive waves in dissipative media, we present a complete discussion of the dispersion relations for both the ordinary and the time-fractional Cattaneo-Maxwell heat equations. Consequently, we provide a complete characterization of the group and phase velocities for these two cases, together with some non-trivial remarks on the nature of wave dispersion in fractional models.Comment: 18 pages, 7 figure

    Quality of Life and psychopathology in adults who underwent Hematopoietic Stem Cell Transplantation (HSCT) in childhood: a qualitative and quantitative analysis.

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    Background: Patients who undergo pediatric Hematopoietic Stem Cell Transplantation (HSCT) may experience long-term psychological sequelae and poor Quality of Life (QoL) in adulthood. This study aimed to investigate subjective illness experience, QoL, and psychopathology in young adults who have survived pediatric HSCT. Method: The study involved patients treated with HSCT in the Hematology-Oncology Department between 1984 and 2007. Psychopathology and QoL were investigated using the SCL-90-R and SF-36. Socio-demographic and medical information was also collected. Finally, participants were asked to write a brief composition about their experiences of illness and care. Qualitative analysis of the texts was performed using T-LAB, an instrument for text analysis that allows the user to highlight the occurrences and co-occurrences of lemma. Quantitative analyses were performed using non-parametric tests (Spearman correlations, Kruskal-Wallis and Mann-Whitney tests). Results: Twenty-one patients (9 males) participated in the study. No significant distress was found on the SCL-90 Global Severity Index, but it was found on specific scales. On the SF-36, lower scores were reported on scales referring to bodily pain, general health, and physical and social functioning. All the measures were significantly (p < 0.05) associated with specific socio-demographic and medical variables (gender, type of pathology, type of HSCT, time elapsed between communication of the need to transplant and effective transplantation, and days of hospitalization). With regard to the narrative analyses, males focused on expressions related to the body and medical therapies, while females focused on people they met during treatment, family members, and donors. Low general health and treatment with autologous HSCT were associated with memories about chemotherapy, radiotherapy, and the body parts involved, while high general health was associated with expressions focused on gratitude (V-Test \ub1 1.96). Conclusion: Pediatric HSCT survivors are more likely to experience psychological distress and low QoL in adulthood compared with the general population. These aspects, along with survivors' subjective illness experience, show differences according to specific medical and socio-demographic variables. Studies are needed in order to improve the care and long-term follow-up of these families

    Attitude toward prescription and clinical monitoring of lithium salts in a sample of Italian psychiatrists: preliminary data

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    Results of international prescribing patterns show that lithium prescription and biochemical drug monitoring seem to differ from a country to another. In spite of clear-cut supporting scientific evidence lithium monitoring is often disregarded, incorrectly used or underused. In Italy the trend of lithium prescriptions and biochemical monitoring is far from what suggested in guidelines; even if there's an impressive paucity of data about lithium monitoring and related iatrogenic risks in our country. In order to assess the current attitude in Italy toward lithium treatment in bipolar disorder we asked to a number of senior psychiatrists, working within the national territory, to fill a 34 items interview. Items were grouped in 8 domains, ranging from prescription pattern to therapeutic drug monitoring and other safety measures to prevent iatrogenic harm during lithium therapy. A preliminary analysis of the very first data, collected mainly in Tuscany, suggested that overall knowledge about lithium prescription and biochemical monitoring were good and the few critical topics found in this preliminary study may be addressed with an improvement in information about lithium therapy

    Fractional diffusions with time-varying coefficients

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    This paper is concerned with the fractionalized diffusion equations governing the law of the fractional Brownian motion BH(t)B_H(t). We obtain solutions of these equations which are probability laws extending that of BH(t)B_H(t). Our analysis is based on McBride fractional operators generalizing the hyper-Bessel operators LL and converting their fractional power LαL^{\alpha} into Erd\'elyi--Kober fractional integrals. We study also probabilistic properties of the r.v.'s whose distributions satisfy space-time fractional equations involving Caputo and Riesz fractional derivatives. Some results emerging from the analysis of fractional equations with time-varying coefficients have the form of distributions of time-changed r.v.'s

    Creep, Relaxation and Viscosity Properties for Basic Fractional Models in Rheology

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    The purpose of this paper is twofold: from one side we provide a general survey to the viscoelastic models constructed via fractional calculus and from the other side we intend to analyze the basic fractional models as far as their creep, relaxation and viscosity properties are considered. The basic models are those that generalize via derivatives of fractional order the classical mechanical models characterized by two, three and four parameters, that we refer to as Kelvin-Voigt, Maxwell, Zener, anti-Zener and Burgers. For each fractional model we provide plots of the creep compliance, relaxation modulus and effective viscosity in non dimensional form in terms of a suitable time scale for different values of the order of fractional derivative. We also discuss the role of the order of fractional derivative in modifying the properties of the classical models.Comment: 41 pages, 8 figure

    A web based communication and information system tool for water management in developing countries

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    This paper deals with the development of an innovative webbased communication and information system tool for water practitioners in Developing Countries. We introduce briefly the functionalities implemented in the webbased Communication and Information System which allows the specialised users in the Water field to improve the network communication through a virtual webbased system. Two implementations have been developed for two communities: 1) the AQUAkNOW Information system (http://www.wkmp.net/new) for practitioners in the field; 2) the EUWI Communication and Information System (http://www.euwi.net/new) for policy makers in charge of the implementation of the European Union Water Initiative

    Lebesgue regularity for differential difference equations with fractional damping

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    We provide necessary and sufficient conditions for the existence and unique-ness of solutions belonging to the vector-valued space of sequences �(Z, X) forequations that can be modeled in the formΔu(n)+Δu(n)=Au(n)+G(u)(n)+ (n), n ∈ Z,,>0,≥0,where X is a Banach space, ∈ �(Z, X), A is a closed linear operatorwith domain D(A) defined on X,andG is a nonlinear function. The oper-ator Δdenotes the fractional difference operator of order >0inthesense of Grünwald-Letnikov. Our class of models includes the discrete timeKlein-Gordon, telegraph, and Basset equations, among other differential differ-ence equations of interest. We prove a simple criterion that shows the existenceof solutions assuming that f is small and that G is a nonlinear term

    The effect of the sterile insect technique on vibrational communication: the case of Bagrada hilaris (Hemiptera: Pentatomidae)

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    The painted bug, Bagrada hilaris, is an agricultural pest in its original areas (Africa, South Asia, and the Middle East), and it has recently been recorded as an invasive species in southwestern part of the US, Chile, Mexico, and two islands in the Mediterranean basin. Its polyphagous diet causes severe damage to economically important crops. The control of this pest is primarily achieved by means of synthetic pesticides, which are often expensive, ineffective, and harmful to the ecosystem. Recent physiological bioassays to assess its potential control through the sterile insect technique demonstrated that mating between untreated females and males irradiated at doses of 64 and 100 Gy, respectively, resulted in 90% and 100% sterility of the eggs produced by the females. In this study, the mating abilities of virgin males irradiated at 60 and 100 Gy with virgin females were measured through a study of short-range courtship mediated by vibrational communication. The results indicate that males irradiated at 100 Gy emit signals with lower peak frequencies, mate significantly less than unirradiated males do, and do not surpass the early stages of courtship. Conversely, males irradiated at 60 Gy present vibrational signal frequencies that are comparable to those of the control and successfully mated males. Our findings suggest that B. hilaris individuals irradiated at 60 Gy are good candidates for the control of this species, given that they retain sexual competitiveness regardless of their sterility, through an area-wide program that incorporates the sterile insect technique

    Environmental quality of the operating theatres in Campania: long lasting monitoring results

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    In this study the microbiological, physical and chemical results of an investigation concerning the environmental conditions of operating theatres in 38 public hospitals of the Campania Government are presented. The analysis of the results has been made by considering specific standards suggested by national and international regulations. The results showed that 84% of the operating theatres presented normal microbiological values, in relation to the total bacterial load, while 16% did not. By considering the microclimatic monitoring 55% of the operating theatres showed normal values while 45% at least a microclimatic index did not. In relation to the concentrations of anaesthetics gases the survey pointed out that the nitrous oxides was within non prescribed environmental limits (50 ppm for N2O); while 15% of the halogenated was not in normal values

    Characterizations and simulations of a class of stochastic processes to model anomalous diffusion

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    In this paper we study a parametric class of stochastic processes to model both fast and slow anomalous diffusion. This class, called generalized grey Brownian motion (ggBm), is made up off self-similar with stationary increments processes (H-sssi) and depends on two real parameters alpha in (0,2) and beta in (0,1]. It includes fractional Brownian motion when alpha in (0,2) and beta=1, and time-fractional diffusion stochastic processes when alpha=beta in (0,1). The latters have marginal probability density function governed by time-fractional diffusion equations of order beta. The ggBm is defined through the explicit construction of the underline probability space. However, in this paper we show that it is possible to define it in an unspecified probability space. For this purpose, we write down explicitly all the finite dimensional probability density functions. Moreover, we provide different ggBm characterizations. The role of the M-Wright function, which is related to the fundamental solution of the time-fractional diffusion equation, emerges as a natural generalization of the Gaussian distribution. Furthermore, we show that ggBm can be represented in terms of the product of a random variable, which is related to the M-Wright function, and an independent fractional Brownian motion. This representation highlights the HH-{\bf sssi} nature of the ggBm and provides a way to study and simulate the trajectories. For this purpose, we developed a random walk model based on a finite difference approximation of a partial integro-differenital equation of fractional type.Comment: 25 pages, 9 figure
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