513 research outputs found

    Observation angles, Fermi coordinates, and the Geodesic-Light-Cone gauge

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    We show that the angular directions locally measured by a static geodesic observer in a generic cosmological background and expressed in the system of Fermi Normal Coordinates always coincide with those expressed in the Geodesic-Light-Cone (GLC) gauge, up to a local transformation which exploits the residual gauge freedom of the GLC coordinates. This is not the case for other gauges - like, for instance, the synchronous and longitudinal gauge - commonly used in the context of observational cosmology. We also make an explicit proposal for the GLC gauge-fixing condition that ensures a full identification of its angles with the observational ones.Comment: 14 pages, version accepted for publication on JCA

    High-energy string-brane scattering: leading eikonal and beyond

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    We extend previous techniques for calculations of transplanckian-energy string-string collisions to the high-energy scattering of massless closed strings from a stack of N Dp-branes in Minkowski spacetime. We show that an effective non-trivial metric emerges from the string scattering amplitudes by comparing them against the semiclassical dynamics of high-energy strings in the extremal p-brane background. By changing the energy, impact parameter and effective open string coupling, we are able to explore various interesting regimes and to reproduce classical expectations, including tidal-force excitations, even beyond the leading-eikonal approximation.Comment: 40 pages, 5 figures, v2: minor corrections, new appendix with a discussion of the Feynman diagrams contributing to the scattering amplitude in the field theory limi

    A prevalence survey and risk analysis of filariosis in dogs from the Mt. Vesuvius area of southern Italy

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    A dog microfilariae prevalence and risk factor survey was conducted in 51 contiguous municipalities of the Mt. Vesuvius area (Campania region, southern Italy) in order to add data to the limited epidemiological information available regarding filarial worms in this zone. Between May 1999 and June 2000, blood samples were collected from 351 asymptomatic dogs. Blood samples were examined using a modified Knott's technique and histochemical staining in order to count and identify microfilariae. The results were subjected to statistical analysis and choroplethic municipal maps (MMs) were drawn by a geographical information system (GIS) software. Microfilariae were detected in 63 of the 351 dogs surveyed, constituting a total filarial prevalence of 17.9%. In particular, 56 dogs (15.9%) showed only microfilariae of Dipetalonema reconditum; three dogs (0.8%) only microfilariae of Dirofilaria repens; two dogs (0.6%) microfilariae of both D. reconditum and D. repens and two dogs (0.6%) microfilariae of both Dirofilaria immitis and D. repens. High D. reconditum prevalence was associated with hunting practice, masculine gender and older dogs. There was also a tendency to find high prevalence in dogs sampled in the afternoon. In conclusion, the presence of microfilariae of D. reconditum in 92% of microfilaraemic dogs indicates that this filarial worm was the predominant filarial species in dogs in the Mt. Vesuvius area. In addition, the general trends of the MMs showed that D. immitis and D. repens were present only in a few municipalities, whereas D. reconditum was widely and homogeneously spread throughout the entire study area

    Classification-Based Screening of Parkinson’s Disease Patients through Graph and Handwriting Signals

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    Parkinson’s disease (PD) is one of the most common neurodegenerative diseases, affecting millions of people worldwide, especially among the elderly population. It has been demonstrated that handwriting impairment can be an important early marker for the detection of this disease. The aim of this study was to propose a simple and quick way to discriminate PD patients from controls through handwriting tasks using machine-learning techniques. We developed a telemonitoring system based on a user-friendly application for drawing tablets that enabled us to collect real-time information about position, pressure, and inclination of the digital pen during the experiment and, simultaneously, to supply visual feedback on the screen to the subject. We developed a protocol that includes drawing and writing tasks, including tasks in the Italian language, and we collected data from 22 healthy subjects and 9 PD patients. Using the collected signals and data from a preexisting database, we developed a machine-learning model to automatically discriminate PD patients from healthy control subjects with an accuracy of 77.5%

    Cystic echinococcosis in the Campania region (southern Italy)

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    Echinococcosis is cosmopolitan zoonosis caused by adult or larval stages of tapeworms belonging to the genus Echinococcus Rudolphi, 1801. Within the genus Echinococcus four species are presently recognised, namely Echinococcus granulosus, E. multilocularis, E. oligarthrus and E. vogeli, and taxonomic revision of the genus is probably needed (Thompson RCA, McManus DC, 2002, Trends Parasitol 18: 452- 457). E. granulosus, the major species of medical and public health importance which causes cystic echinococcosis (hydatidosis), has a global distribution

    Regge behavior saves string theory from causality violations

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    Higher-derivative corrections to the Einstein-Hilbert action are present in bosonic string theory leading to the potential causality violations recently pointed out by Camanho et al. [1]. We analyze in detail this question by considering high-energy string-brane collisions at impact parameters b ≤ l s (the string-length parameter) with l s ≫ R p (the characteristic scale of the D p -brane geometry). If we keep only the contribution of the massless states causality is violated for a set of initial states whose polarization is suitably chosen with respect to the impact parameter vector. Such violations are instead neatly avoided when the full structure of string theory — and in particular its Regge behavior — is taken into account

    Efficacy and safety of artemether against a natural Fasciola hepatica infection in sheep

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    Triclabendazole is the current drug of choice against Fasciola spp. infections in livestock, but resistance has become a major problem. In this study, we assessed the efficacy and safety of artemether, a derivative of artemisinin, in sheep with a low natural Fasciola hepatica infection. Artemether was administered orally or intramuscularly; sheep were monitored for 8 h posttreatment and then once daily for adverse events, and drug efficacy was estimated by fecal egg count reductions and worm burden reductions. Single 40- and 80-mg/kg oral doses of artemether showed no effect on F. hepatica egg and worm burden. Treatment with a single 160-mg/kg intramuscular dose of artemether significantly reduced the egg burden (64.9%) and worm burden (91.3%). At half this dose, a worm burden reduction of 65.3% was obtained, which was still statistically significant (P < 0.05). The lowest intramuscular dose of artemether investigated (40mg/kg) yielded no effect on egg counts and worm burden. There were no adverse events due to artemether; however, two abortions were observed 7days posttreatment. In conclusion, artemether shows interesting fasciocidal properties in sheep, but embryotoxicity is of concern. Further studies are warranted to assess the potential of additional artemisinin derivatives and other peroxidic compounds for the treatment of Fasciola spp. infections in different ruminant

    Microscopic unitary description of tidal excitations in high-energy string-brane collisions

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    The eikonal operator was originally introduced to describe the effect of tidal excitations on higher-genus elastic string amplitudes at high energy. In this paper we provide a precise interpretation for this operator through the explicit tree-level calculation of generic inelastic transitions between closed strings as they scatter off a stack of parallel Dp-branes. We perform this analysis both in the light-cone gauge, using the Green-Schwarz vertex, and in the covariant formalism, using the Reggeon vertex operator. We also present a detailed discussion of the high energy behaviour of the covariant string amplitudes, showing how to take into account the energy factors that enhance the contribution of the longitudinally polarized massive states in a simple way.Comment: 58 page

    Canine faecal contamination and parasitic risk in the city of Naples (southern Italy)

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    BACKGROUND: Dogs are associated with more than 60 zoonotic diseases among which, parasitosis and, in particular, helminthosis, can pose serious public-health concerns worldwide. Many canine gastrointestinal parasites eliminate their dispersion elements (eggs, larvae, oocysts) by the faecal route. The quantity of canine faeces deposited on public and private property in cities worldwide is both a perennial nuisance and an important health issue. Public sites such as playgrounds, parks, gardens, public squares and sandpits may be an important source of human infection. The aim of this study was to evaluate the extent of both canine faecal contamination in the city of Naples (southern Italy), and presence of canine parasitic elements, with particular regard to those which are potential agents of zoonosis. A regular grid of sub-areas (1 km Ă— 700 m) was overlaid on the city map using a Geographical Information System (GIS). In each sub-area the straightest 1 km transect was drawn and digitalized on-screen in the GIS. Between February and May 2005 canine faeces were counted along the 1 km transects in 143 sub-areas, and 415 canine faecal samples were collected and submitted to coprological examinations. Negative binomial regression models and Gaussian random effects models were used to analyze the association between faeces count and human population density taking into account for extraPoisson variability. Logistic regression model was used to evaluate the association between positivity to parasitic elements and number of canine faeces. RESULTS: Out of the 143 studied sub-areas, 141 (98.6%) contained canine faeces. There was a strong spatial gradient with 48% of the total variability accounted by between neighbourhood variability; a positive association between the number of faeces and the human population density was found. Seventy (over 415, 16.9%) canine faecal samples were positive for parasitic elements. There was no association between positivity to parasitic elements and the number of canine faeces. Eggs of Toxocara canis, Toxascaris leonina, Ancylostoma caninum and Trichuris vulpis were found, as well as oocysts of Isospora canis. CONCLUSION: In conclusion, the results of the present study, conducted using GIS both for planning and sampling and for evaluation and presentation of findings, showed the presence of canine faecal contamination in the city of Naples, and the presence of canine parasitic elements, some of which are potential agents of zoonosis

    The effect of moxidectin 0,1% vs ivermectin 0,08% on milk production in sheep naturally infected by gastrointestinal nematodes

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    BACKGROUND: Gastrointestinal nematode (GIN) infection is one of the main constraints to sheep production both in temperate and tropical countries. Economic losses caused by GIN are related to decreased production, treatment costs and even animal death. The present paper was aimed at assessing the anthelmintic efficacy (based on faecal egg count reduction) of moxidectin and ivermectin both admistered per os at dose rate of 0.2 mg/Kg body weight and the benefit of anthelmintic treatments on milk production in a commercial dairy sheep farms in central Italy whose animals were naturally infected by GIN. RESULTS: The treatment with moxidectin was highly effective (> 98%) from day 7 until day 75, and effective (90-98%) until day 105. The treatment with ivermectin was highly effective (> 98%) from day 7 until day 14, effective (90-98%) at day 28 and moderately effective (80-89%) on day 45. The milk productions in the treated groups were significantly higher than those of the control group. CONCLUSION: In conclusion, the results of the present study demonstrated that moxidectin and ivermectin adminstered per os according to the manufacturer's instructions were both effective and safe anthelmintics in sheep. The total milk production was higher in the treated groups than the control group. Overall, animals treated with moxidectin had a milk production 40.8% higher than control group; whereas animals treated with ivermectin had a milk production 32.2% higher than control group
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