127 research outputs found

    On the man-made contamination on ULF measurements: evidence for disturbances related to an electrified DC railway

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    Abstract. An analysis of measurements performed at L'Aquila (Italy) during a deep minimum of solar and magnetospheric activity (2008–2010) allowed for the evaluation of possible contamination of the ultralow-frequency (ULF) spectrum (f ≈ 1–500 mHz) from artificial disturbances, practically in absence of natural signals. In addition, the city evacuation and the interruption of all industrial and social activities after the strong earthquake of 6 April 2009 allowed also for the examination of possible changes of the contamination level under remarkably changed environmental conditions. Our analysis reveals a persistent, season-independent, artificial signal, with the same characteristics in the H and Z components, that affects during daytime hours the entire spectrum; such contamination persists after the city evacuation. We speculate that the DC electrified railway (located ≈ 33 km from the Geomagnetic Observatory of L'Aquila, it maintained the same train traffic after the earthquake) is responsible for the observed disturbances

    ULF geomagnetic pulsations at different latitudes in Antarctica

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    We present a study aimed to characterize the ULF (1–100 mHz) geomagnetic pulsation activity in the polar cap at different latitudes. We used magnetic measurements obtained through 2005–2007 in Antarctica, at Dome C (89° S corrected geomagnetic latitude) and at Terra Nova Bay (80° S corrected geomagnetic latitude). The results indicate a solar wind control of the wave activity, more important at larger distances from the cusp, as well as a significant role of the local ionospheric conditions. The different position of the two stations, with respect to the cusp and closed field lines, is responsible for the observed different pulsation characteristics. At Terra Nova Bay, due to the approaching of the station to the cusp and closed field lines in the daytime, the ULF power is characterized by a maximum around noon; daytime pulsation events in the Pc5 frequency band are related to the fundamental field line resonances occurring at lower latitudes, while higher harmonics of the fundamental may account for the characteristics of Pc3–4 pulsations. In the nighttime, at Pc3 frequencies, the results suggest waves propagating sunward, possibly due to the transmission of upstream waves from the magnetosheath via the magnetotail lobes. At Dome C, near the geomagnetic pole and very far from closed field lines, the ULF power in any frequency band only shows an enhancement in the postmidnight sector, more pronounced for Pc3 pulsations. The ULF activity appears to be driven by processes occurring in the magnetotail: in particular, nighttime Pc3 pulsation events may be originated from upstream wave penetration through the magnetotail lobes

    The 6 April 2009 earthquake at L'Aquila: a preliminary analysis of magnetic field measurements

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    Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L'Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources

    The 6 April 2009 earthquake at L’Aquila: a preliminary analysis of magnetic field measurements

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    Several investigations reported the possible identification of anomalous geomagnetic field signals prior to earthquake occurrence. In the ULF frequency range, candidates for precursory signatures have been proposed in the increase in the noise background and polarization parameter (i.e. the ratio between the amplitude/power of the vertical component and that one of the horizontal component), in the changing characteristics of the slope of the power spectrum and fractal dimension, in the possible occurrence of short duration pulses. We conducted, with conventional techniques of data processing, a preliminary analysis of the magnetic field observations performed at L’Aquila during three months preceding the 6 April 2009 earthquake, focusing attention on the possible occurrence of features similar to those identified in previous events. Within the limits of this analysis, we do not find compelling evidence for any of the features which have been proposed as earthquake precursors: indeed, most of aspects of our observations (which, in some cases, appear consistent with previous findings) might be interpreted in terms of the general magnetospheric conditions and/or of different sources

    Some aspects of man-made contamination on ULF measurements

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    An analysis of the man made contamination on ULF measurements in highly populated areas has been conducted at several suitably chosen sites in Western Europe. The experimental results show common characteristics at different stations with clear evidence for an additional working day contamination with respect to weekends. These effects more clearly emerge in the vertical component that is less influenced by natural signals. A similar analysis conducted at Terra Nova Bay does not reveal any clear evidence for man made disturbances on Antarctic measurements.<br><br> <b>Key words.</b> (Magnetospheric physics, instruments and techniques; Solar wind-magnetosphere interaction) (Geomagnetism and paleomagnetism time variations, diurnal to secular

    HLA-G14bp ins/del polymorphism and post-transplant weight gain in kidney transplantation. Potential implications beyond tolerance

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    Background: Human leukocyte antigen (HLA)-G is a non-classical HLA molecule with immunomodulant and immunosuppressive functions, involved in transplantation tolerance. HLA-G14bp ins/del polymorphism in exon 8 has been associated with allograft rejection and kidney transplant outcome, with controversial results. We investigated associations of HLA-G14bp ins/del polymorphism on onset of some of the main post-transplant risk factors, like excess body weight, lipid abnormalities, increased fasting plasma glucose. Polymorphisms of cytokines with both immunosuppressive and metabolic effects were also assessed for comparisons and associated analysis. Methods: The present study involved kidney transplant recipients (n = 173) in which body mass index, cholesterol, triglycerides, fasting plasma glucose were registered in the first years after transplantation and analyzed in association with genotypes. Presence of hypertension and smoking habits, demographic, transplant-related and therapeutic data of patients were also recorded. Polymerase chain reaction, sequence-specific primer amplification and Taqman allelic discrimination techniques were used for genotyping of HLA-G14bp ins/del, interleukin (IL)-10(-1082G > A,-819 T > C,-592A > C), transforming growth factor-β(+ 869 T > C,+915C > G), IL-6(-174G > C), tumor necrosis factor-α(-308G > A) and IL-18(-137G > C,-607C > A). Effects of genotypes on clinical markers at each time point (pre-transplant and 1 to 5 years after transplant) were analyzed using a repeated-measures general linear model analysis; adjustment for potential confounders was performed. Results: Results showed that HLA-G14bp ins/ins was significantly associated with obesity, in particular after transplantation (3 years, p = 0.002, OR = 4.48, 95% CI:1.76-11.41). Post-transplant body mass index was significantly increased in HLA-G14bp ins/ins carriers (3 and 4 years, p = 0.033 and p = 0.044); effects of HLA-G14bp genotypes on post-transplant BMI were confirmed by using repeated-measures analysis and after controlling for confounding variables. Cytokine genotypes did not associate with the examined factors. Conclusions: The study of transplanted patients allowed to evidence a potential relationship between post-transplant weight gain and HLA-G14bp ins/del polymorphism, previously involved in rejection for its immunosuppressive/tolerogenic activity. This novel association could widen the knowledge of the role and functions of HLA-G molecules in diseases and transplantation

    Reduced number and function of peripheral dendritic cells in coeliac disease.

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    Dendritic cells (DC) play a pivotal role in shaping the immune response in both physiological and pathological conditions. In peripheral blood at least two subsets, the myeloid and plasmacytoid, have been described as having different T stimulatory functions and a variable degree of maturation. Certainly, antigen presentation plays a crucial role in the pathogenesis of coeliac disease and circulating immune cells are thought to reflect the state of immune response within the gut. Therefore,we aimed to investigate the quantitative and phenotypical modifications of peripheral bloodDC, together with their functional properties, in this pathological condition. Blood samples from 11 untreated patients before and after a course of gluten-free diet, 27 treated patients and 14 controls underwent flow-cytometric analysis, while immunomagnetically sorted DC from the CD patients and eight human leucocyte antigen (HLA)-DQ2/8+ bone marrow donors were used to evaluate maturation status through the CD83 expression, cytokine profile for interleukin (IL)-6, IL-10, IL-12 and interferon (IFN)-a by enzyme-linked immunosorbent assay (ELISA), and functional properties by mixed leucocyte reaction before and after pulsing with digested gliadin. We found that in both untreated and treated patients, a significant reduction of the entire DC population, mainly the plasmacytoid subset, in comparison to healthy controls was observed. In active disease, an impaired allogenic lymphocyte reaction and a significant reduction of IFN-a production, paralleled by the presence of a more immature status, were also demonstrated. All the latter modifications have been reverted by pulsing DC with digested gliadin

    Geomagnetic field observations at a new Antarctic site, within the AIMNet project

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    During the 2007-2008 antarctic campaign, the Italian PNRA installed a Low Power Magnetometer within the framework of the AIMNet (Antarctic International Magnetometer Network) project, proposed and coordinated by BAS. The magnetometer is situated at Talos Dome, around 300 km geographically North-West from Mario Zucchelli Station (MZS), and approximately at the same geomagnetic latitude as MZS. In this work we present a preliminary analysis of the geomagnetic field 1-min data, and a comparison with simultaneous data from different Antarctic stations

    Distribution of killer cell immunoglobulin-like receptors genes in the Italian Caucasian population

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    BACKGROUND: Killer cell immunoglobulin-like receptors (KIRs) are a family of inhibitory and activatory receptors that are expressed by most natural killer (NK) cells. The KIR gene family is polymorphic: genomic diversity is achieved through differences in gene content and allelic polymorphism. The number of KIR loci has been reported to vary among individuals, resulting in different KIR haplotypes. In this study we report the genotypic structure of KIRs in 217 unrelated healthy Italian individuals from 22 immunogenetics laboratories, located in the northern, central and southern regions of Italy. METHODS: Two hundred and seventeen DNA samples were studied by a low resolution PCR-SSP kit designed to identify all KIR genes. RESULTS: All 17 KIR genes were observed in the population with different frequencies than other Caucasian and non-Caucasian populations; framework genes KIR3DL3, KIR3DP1, KIR2DL4 and KIR3DL2 were present in all individuals. Sixty-five different profiles were found in this Italian population study. Haplotype A remains the most prevalent and genotype 1, with a frequency of 28.5%, is the most commonly observed in the Italian population. CONCLUSION: The Italian Caucasian population shows polymorphism of the KIR gene family like other Caucasian and non-Caucasian populations. Although 64 genotypes have been observed, genotype 1 remains the most frequent as already observed in other populations. Such knowledge of the KIR gene distribution in populations is very useful in the study of associations with diseases and in selection of donors for haploidentical bone marrow transplantation
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