180 research outputs found

    Dicluster Stopping in a Degenerate Electron Gas

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    In this paper we report on our theoretical studies of various aspects of the correlated stopping power of two point-like ions (a dicluster) moving in close but variable vicinity of each other in some metallic target materials the latter being modelled by a degenerate electron gas with appropriate densities. Within the linear response theory we have made a comprehensive investigation of correlated stopping power, vicinage function and related quantities for a diproton cluster in two metallic targets, aluminum and copper, and present detailed and comparative results for three approximations to the electron gas dielectric function, namely the plasmon-pole approximation without and with dispersion as well as with the random phase approximation. The results are also compared, wherever applicable, with those for an individual projectile.Comment: 29 figures, LaTe

    Surveillance of enteric virus infections in a neonatal intensive care unit.

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    Objective. To investigate the epidemiology of neonatal viral gastroenteritis compared to the circulation of enteric viruses in children, 109 newborns in the NICU of Mother and Child Department and 214 children with enteritis admitted to the \u201cG. Di Cristina\u201d Children\u2019s Hospital in Palermo were monitored for Rotavirus, Adenovirus, Astrovirus and Norovirus infections. Methods. Stool samples were examined by EIA to detect viral antigens. Rotavirus strains were subjected to P- and G-typing. Results. A Norovirus strain was detected in one neonatal stool specimen whereas an astrovirus strain was dectected in two neonatal specimens. No Rotavirus or Adenovirus infection was identified among the newborn infants, while Rotavirus infections were detected in 24.8% of the symptomatic children. Type G4P[8] constituted 43.4% of the Rotavirus strains, followed by G2P[4] (18.9%), G3P[8] (17%), G1P[8] (13.2%) and G9P[8] (1.9%). Overall, Norovirus, Adenovirus and Astrovirus strains were responsible for 15.4% of infections in the paediatric population with diarrhoea. Conclusions. Viruses are diffuse agents of infection in children with enteritis. Virological tests have to be performed to diagnose enteric infections in the paediatric population. Maternal immunity to common Rotavirus strains combined with the limited circulation of the emerging G9 Rotavirus type among our population may account for the absence of Rotavirus infections in newborn infants

    Quasi-classical Molecular Dynamics Simulations of the Electron Gas: Dynamic properties

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    Results of quasi-classical molecular dynamics simulations of the quantum electron gas are reported. Quantum effects corresponding to the Pauli and the Heisenberg principle are modeled by an effective momentum-dependent Hamiltonian. The velocity autocorrelation functions and the dynamic structure factors have been computed. A comparison with theoretical predictions was performed.Comment: 8 figure

    Sarcoma de Kaposi clĂĄsico en una adolescente inmunocompetente

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    El sarcoma de Kaposi (KS) es una enfermedad prevalente en África, se sabe de su existencia hace mĂĄs de un siglo, por lo que se le ha denominado endĂ©mico. Desde la apariciĂłn del virus de la inmunodeficiencia humana (VIH) y el sĂ­ndrome de inmunodeficiencia adquirida (SIDA), se reconociĂł un tipo de sarcoma de Kaposi, el llamado epidĂ©mico mĂĄs agresivo y diseminado, que recientemente se ha relacionado con el virus del herpes tipo 8. El sarcoma de Kaposi clĂĄsico se presenta en pacientes ancianos como manchas vasculares discretamente sobre-elevadas que se localizan predominantemente en los miembros inferiores, rara vez sucede en la infancia. Se presenta un caso de sarcoma de Kaposi clĂĄsico en una adolescente mexicana inmunocompetente.   Abstract Kaposi’s sarcoma (KS) is a prevalent disease in Africa and is known of its existence for more than a century, which has been called endemic. Since the emergence of HIV (HIV) and acquired immunodeficiency syndrome (AIDS), a type of Kaposi’s sarcoma more aggressive and spread was recognized recently has been linked to the virus type 8 herpes, he has called classic Kaposi’s sarcoma. It occurs in elderly patients as vascular patches localized predominantly in the lower limbs, rarely seen in childhood. We report a case of classic Kaposi’s sarcoma in an immunocompetent Mexican teenager. &nbsp

    Sarcoma de Kaposi clĂĄsico en una adolescente inmunocompetente

    Get PDF
    El sarcoma de Kaposi (KS) es una enfermedad prevalente en África, se sabe de su existencia hace mĂĄs de un siglo, por lo que se le ha denominado endĂ©mico. Desde la apariciĂłn del virus de la inmunodeficiencia humana (VIH) y el sĂ­ndrome de inmunodeficiencia adquirida (SIDA), se reconociĂł un tipo de sarcoma de Kaposi, el llamado epidĂ©mico mĂĄs agresivo y diseminado, que recientemente se ha relacionado con el virus del herpes tipo 8. El sarcoma de Kaposi clĂĄsico se presenta en pacientes ancianos como manchas vasculares discretamente sobre-elevadas que se localizan predominantemente en los miembros inferiores, rara vez sucede en la infancia. Se presenta un caso de sarcoma de Kaposi clĂĄsico en una adolescente mexicana inmunocompetente.   Abstract Kaposi’s sarcoma (KS) is a prevalent disease in Africa and is known of its existence for more than a century, which has been called endemic. Since the emergence of HIV (HIV) and acquired immunodeficiency syndrome (AIDS), a type of Kaposi’s sarcoma more aggressive and spread was recognized recently has been linked to the virus type 8 herpes, he has called classic Kaposi’s sarcoma. It occurs in elderly patients as vascular patches localized predominantly in the lower limbs, rarely seen in childhood. We report a case of classic Kaposi’s sarcoma in an immunocompetent Mexican teenager. &nbsp

    The role of E1-E2 interplay in multiphonon Coulomb excitation

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    In this work we study the problem of a charged particle, bound in a harmonic-oscillator potential, being excited by the Coulomb field from a fast charged projectile. Based on a classical solution to the problem and using the squeezed-state formalism we are able to treat exactly both dipole and quadrupole Coulomb field components. Addressing various transition amplitudes and processes of multiphonon excitation we study different aspects resulting from the interplay between E1 and E2 fields, ranging from classical dynamic polarization effects to questions of quantum interference. We compare exact calculations with approximate methods. Results of this work and the formalism we present can be useful in studies of nuclear reaction physics and in atomic stopping theory.Comment: 10 pages, 6 figure

    Breeding systems of floral colour forms in the Drosera cistiflora species complex

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    The study was supported by the National Research Foundation of South Africa (Grant 46372 to SDJ).Variation in plant breeding systems has implications for pollinator‐mediated selection on floral traits and the ecology of populations. Here we evaluate pollinator contribution to seed production, self‐compatibility and pollen limitation in different floral colour forms of Drosera cistiflora sensu lato (Droseraceae). These insectivorous perennial plants are endemic to fynbos and renosterveld vegetation in the Cape Floristic Region of South Africa, and the species complex includes five floral colour forms (pink, purple, red, white and yellow), some of which are known to be pollinated by beetles. Controlled hand‐pollination experiments were conducted in 15 populations of D. cistiflora s.l. (two to four populations per floral colour form) to test whether the colour forms vary in their degree of self‐compatibility and their ability to produce seeds through autonomous self‐fertilization. Yellow‐flowered forms were highly self‐incompatible, while other floral colour forms exhibited partial self‐compatibility. Seed set resulting from autonomous selfing was very low, and pollinator dependence indices were high in all populations. Since hand cross‐pollination resulted in greater seed set than open pollination in 13 of the 15 populations, we inferred that seed production is generally pollen‐limited.Drosera cistiflora s.l. typically exhibits high levels of pollinator dependence and pollen limitation. This is unusual among Drosera species worldwide and suggests that pollinators are likely to mediate strong selection on attractive traits such as floral colour and size in D. cistiflora s.l. These results also suggest that the floral colour forms of D. cistiflora s.l. which are rare and threatened are likely to be vulnerable to local extinction if mutualisms were to collapse indefinitely.PostprintPeer reviewe

    Unravelling heterogeneous malaria transmission dynamics in the Peruvian Amazon: insights from a cross-sectional survey.

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    BACKGROUND: Malaria remains a global health challenge, particularly in Peru's Loreto region. Despite ongoing efforts, high infection rates and asymptomatic cases perpetuate transmission. The Peruvian Ministry of Health's "Zero Malaria Plan" targets elimination. This novel study combines microscopic, molecular, and serological techniques to assess transmission intensity, identify epidemiological risk factors, and characterize species-specific patterns across villages. The findings aim to inform targeted interventions and support broader malaria elimination efforts in line with the Zero Malaria Plan initiative. METHODS: A cross-sectional malaria survey was conducted in the Zungarococha community, comprising the villages Llanchama (LL), Ninarumi (NI), Puerto Almendra (PA), and Zungarococha (ZG), using microscopic, molecular, and serological techniques to evaluate malaria transmission intensity. Statistical analysis, including multivariate-adjusted analysis, seroprevalence curves, and spatial clustering analysis, were performed to assess malaria prevalence, exposure, and risk factors. RESULTS: The survey revealed a high prevalence of asymptomatic infections (6% by microscopy and 18% by PCR), indicating that molecular methods are more sensitive for detecting asymptomatic infections. Seroprevalence varied significantly between villages, reflecting the heterogeneous malaria transmission dynamics. Multivariate analysis identified age, village, and limited bed net use as significant risk factors for malaria infection and species-specific exposure. Seroprevalence curves demonstrated community-specific patterns, with Llanchama and Puerto Almendra showing the highest seroconversion rates for both Plasmodium species. CONCLUSIONS: The study highlights the diverse nature of malaria transmission in the Loreto region, particularly nothing the pronounced heterogeneity as transmission rates decline, especially in residual malaria scenarios. The use of molecular and serological techniques enhances the detection of current infections and past exposure, aiding in the identification of epidemiological risk factors. These findings underscore the importance of using molecular and serological tools to characterize malaria transmission patterns in low-endemic areas, which is crucial for planning and implementing targeted interventions and elimination strategies. This is particularly relevant for initiatives like the Zero Malaria Plan in the Peruvian Amazon
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