761 research outputs found

    Assessing influence factors on daily ammonia and greenhouse gas concentrations from an open-sided cubicle barn in hot mediterranean climate

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    Measurement of gas concentrations constitutes basic knowledge for the computation of emissions from livestock buildings. Although it is well known that hot climate conditions increase gas emissions, in the literature the relation between gas concentrations from open barns and animalrelated parameters has not been investigated yet. This study aimed at filling this gap by evaluating daily gas concentrations within an open-sided barn in hot Mediterranean climate. The influence of microclimatic parameters (MC) and cow behavior and barn management (CBBM) were evaluated for ammonia (NH3 ), methane (CH4 ), and carbon dioxide (CO2 ) concentrations. Results showed that both MC and CBBM affected concentrations of NH3 (p < 0.02), CH4 (p < 0.001), and CO2 (p < 0.001). Higher values of NH3 concentration were detected during the cleaning of the floor by a tractor with scraper, whereas the lowest NH3 concentrations were recorded during animal lying behavior. Measured values of CO2 and CH4 were highly correlated (C = 0.87–0.89) due to the same sources of production (i.e., digestion and respiration). The different management of the cooling systems during the two observation periods reduced significantly CH4 concentrations in the barn when the cooling system in the feeding area was switched off. Based on methodological choices due to the specific barn typology, parameters related to animals can provide information on the variation of gas concentrations in the barn environment in hot climate conditions

    Cross Sectional and Longitudinal Fuzzy Clustering of the NUTS and Positioning of the Italian Regions with Respect to the Regional Competitiveness Index (RCI) Indicators with Contiguity Constraints

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    In socio-economical clustering often the empirical information is represented by time-varying data generated by indicators observed over time on a set of subnational (regional) units. Usually among these units may exist contiguity relations, spatial but not only.In this paper we propose a fuzzy clustering model of multivariate time-varying data, the longitudinal fuzzy C-Medoids clustering with contiguity constraints. The temporal aspect is dealt with by using appropriate measures of dissimilarity between time trajectories. The contiguity among units is dealt with adding a contiguity matrix as a penalization term in the clustering model.The cross sectional fuzzy C-Medoids clustering with contiguity constraints is obtained considering one instant of time. The model is applied to the classification of the European NUTS on the basis of the observed dynamics of the Basic, Efficiency and Innovation subindexes of the Regional Competitiveness Index (RCI) 2013 and 2016. The positioning of the Italian regions is analyzed through the values of the medoids of the clusters and shows the peculiarities of the regions with respect to the subindexes either in single times or in the dynamic. Two contiguity constraints, one based on the European Western, Southern, Central and Northern geographic areas and one on the level of GDP—taken into account in the computation of the RCI—are also introduced in the models

    Analysing cluster evolution using repeated cross-sectional ordinal data

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    This study contributes to the existing literature on tourism market segmentation by providing a new matching-clustering procedure that allows patterns of behaviours to be identified using repeated cross-sectional surveys. By extracting equivalent samples over time, the matching method allows inter-temporal cluster analyses to be performed so that a deeper insight into a phenomenon can be obtained beyond the traditional aggregate level of understanding. The paper provides a step-by-step description of the matching-clustering procedure that can be easily replicated, both within and outside the tourism field, when repeated cross-sectional data are available. From a practical and managerial perspective, the proposed procedure helps destination managers and municipal- ities to describe and verify the efficacy of policy and strategies adopted over years without the necessity to rely on longitudinal surveys, which are often difficult to conduct

    Fuzzy clustering with entropy regularization for interval-valued data with an application to scientific journal citations

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    In recent years, the research of statistical methods to analyze complex structures of data has increased. In particular, a lot of attention has been focused on the interval-valued data. In a classical cluster analysis framework, an interesting line of research has focused on the clustering of interval-valued data based on fuzzy approaches. Following the partitioning around medoids fuzzy approach research line, a new fuzzy clustering model for interval-valued data is suggested. In particular, we propose a new model based on the use of the entropy as a regularization function in the fuzzy clustering criterion. The model uses a robust weighted dissimilarity measure to smooth noisy data and weigh the center and radius components of the interval-valued data, respectively. To show the good performances of the proposed clustering model, we provide a simulation study and an application to the clustering of scientific journals in research evaluation

    Optical Relative Calibration and Stability Monitoring for the Auger Fluorescence Detector

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    The stability of the fluorescence telescopes of the Pierre Auger Observatory is monitored with the optical relative calibration setup. Optical fibers distribute light pulses to three different diffuser groups within the optical system. The total charge per pulse is measured for each pixel and compared with reference calibration measurements. This allows monitoring the short and long term stability with respect of the relative timing between pixels and the relative gain for each pixel. The designs of the LED calibration unit (LCU) and of the Xenon flash lamp used for relative calibration, are described and their capabilities to monitor the stability of the telescope performances are studied. We report the analysis of relative calibration data recorded during 2004. Fluctuations in the relative calibration constants provide a measure of the stability of the FD.Comment: 4 pp. To appear in the proceedings of 29th International Cosmic Ray Conference (ICRC 2005), Pune, India, 3-11 Aug 200

    The Central Laser Facility at the Pierre Auger Observatory

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    The Central Laser Facility is located near the middle of the Pierre Auger Observatory in Argentina. It features a UV laser and optics that direct a beam of calibrated pulsed light into the sky. Light scattered from this beam produces tracks in the Auger optical detectors which normally record nitrogen fluorescence tracks from cosmic ray air showers. The Central Laser Facility provides a "test beam" to investigate properties of the atmosphere and the fluorescence detectors. The laser can send light via optical fiber simultaneously to the nearest surface detector tank for hybrid timing analyses. We describe the facility and show some examples of its many uses.Comment: 4 pages, 5 figures, submitted to 29th ICRC Pune Indi

    Role of PET/CT in the detection of liver metastases from colorectal cancer

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    The aim of this study was to compare the diagnostic accuracy of 2-[fluorine-18] fluoro-2-deoxy-D-glucose positron emission tomography (F-18-FDG-PET) and computed tomography (CT) with PET/CT in the detection of liver metastases during tumour staging in patients suffering from colorectal carcinoma for the purposes of correct surgical planning and follow-up. A total of 467 patients underwent a PET/CT scan using an iodinated contrast medium. We compared images obtained by the single PET scan, the single CT scan and by the fusion of the two procedures (PET/CT). The final diagnosis was obtained by histological examination and/or by the follow-up of all patients, including those who did not undergo surgery or biopsy. The PET scan had 94.05% sensitivity, 91.60% specificity and 93.36% accuracy; the CT scan had 91.07% sensitivity, 95.42% specificity and 92.29% accuracy. The combined procedures (PET/CT) had the following values: sensitivity 97.92%, specificity 97.71% and accuracy 97.86%. This study indicates that PET/CT is very useful in staging and restaging patients suffering from colorectal cancer. It was particularly useful when recurrences could not be visualised either clinically or by imaging despite increasing tumour markers, as it guaranteed an earlier diagnosis. PET/CT not only provides high diagnostic performance in terms of sensitivity and specificity, enabling modification of patient treatment, but it is also a unique, high-profile procedure that can produce cost savings

    Electronic Circular Dichroism Detects Conformational Changes Associated with Proteasome Gating Confirmed Using AFM Imaging

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    Many chronic diseases, including cancer and neurodegeneration, are linked to proteasome dysregulation. Proteasome activity, essential for maintaining proteostasis in a cell, is controlled by the gating mechanism and its underlying conformational transitions. Thus, developing effective methods to detect gate-related specific proteasome conformations could be a significant contribution to rational drug design. Since the structural analysis suggests that gate opening is associated with a decrease in the content of α-helices and β-sheets and an increase in random coil structures, we decided to explore the application of electronic circular dichroism (ECD) in the UV region to monitor the proteasome gating. A comparison of ECD spectra of wild type yeast 20S proteasome (predominantly closed) and an open-gate mutant (α3ΔN) revealed an increased intensity in the ECD band at 220 nm, which suggests increased contents of random coil and β-turn structures. This observation was further supported by evaluating ECD spectra of human 20S treated with low concentration of SDS, known as a gate-opening reagent. Next, to evaluate the power of ECD to probe a ligand-induced gate status, we treated the proteasome with H2T4, a tetracationic porphyrin that we showed previously to induce large-scale protein conformational changes upon binding to h20S. H2T4 caused a significant increase in the ECD band at 220 nm, interpreted as an induced opening of the 20S gate. In parallel, we imaged the gate-harboring alpha ring of the 20S with AFM, a technique that we used previously to visualize the predominantly closed gate in latent human or yeast 20S and the open gate in α3ΔN mutant. The results were convergent with the ECD data and showed a marked decrease in the content of closed-gate conformation in the H2T4-treated h20S. Our findings provide compelling support for the use of ECD measurements to conveniently monitor proteasome conformational changes related to gating phenomena. We predict that the observed association of spectroscopic and structural results will help with efficient design and characterization of exogenous proteasome regulators

    Bee diversity in fragmented areas of Volcano Etna (Sicily, Italy) at different degrees of anthropic disturbance (Hymenoptera: Apoidea, Anthophila)

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    The present three-year study traces the diversity of four bee communities in fragmented pedemontane areas of Volcano Etna (Catania province, Sicily) near the Metropolitan City of Catania, under different land management regimes. The selected areas comprise two different urban parks within Catania (Parco Gioeni and Parco degli Ulivi), a Nature Reserve (Complesso Immacolatelle e Micio Conti, San Gregorio di Catania), and an agroecosystem (a citrus orchard, Aci Catena). Previous data obtained from a well-investigated area (Leucatia, north of Catania) have been used as a control for bee diversity for this study. The results include an outline of bee species richness, data on the composition of bee communities, and seasonal patterns, using several diversity indexes. The study of bee diversity shows a total of 163 species, arranged in five families. The four investigated locations include 104 species arranged in four families: Andrenidae (20 species), Halictidae (15 species), Megachilidae (31 species), and Apidae (38 species); with a similar number of species (102) recorded in the control site (Leucatia). The study highlights strong seasonal variations of bee communities in all investigated sites, with differentiated seasonal patterns, whose compositions are affected mainly by forage sources, suitable nesting sites, as well as human activities. The data obtained provide a rough but basilar framework to assess management strategies to maintain adequate levels of bee diversity, especially for those areas with moderate to high environmental fragmentation. Our findings highlight the importance of season-long sampling of bee population factors if used as indicators in ecological studies
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