118,057 research outputs found
Connecting blazars with ultrahigh-energy cosmic rays and astrophysical neutrinos
No full textWe present a strong hint of a connection between high-energy γ-ray emitting blazars, very high energy neutrinos, and ultrahigh-energy cosmic rays. We first identify potential hadronic sources by filtering γ-ray emitters in spatial coincidence with the high-energy neutrinos detected by IceCube. The neutrino filtered γ-ray emitters are then correlated with the ultrahigh-energy cosmic rays from the Pierre Auger Observatory and the Telescope Array by scanning in γ-ray flux (Fγ) and angular separation (θ) between sources and cosmic rays. A maximal excess of 80 cosmic rays (42.5 expected) is found at θ ≤ 10° from the neutrino-filtered γ-ray emitters selected from the second hard Fermi-LAT catalogue (2FHL) and for Fγ(>50 GeV) ≥ 1.8 × 10−11 ph cm−2 s−1. The probability for this to happen is 2.4 × 10−5, which translates to ∼2.4 × 10−3 after compensation for all the considered trials. No excess of cosmic rays is instead observed for the complement sample of γ-ray emitters (i.e. not in spatial connection with IceCube neutrinos). A likelihood ratio test comparing the connection between the neutrino-filtered and the complement source samples with the cosmic rays favours a connection between neutrino-filtered emitters and cosmic rays with a probability of ∼1.8 × 10−3 (2.9σ) after compensation for all the considered trials. The neutrino-filtered γ-ray sources that make up the cosmic rays excess are blazars of the high synchrotron peak type. More statistics is needed to further investigate these sources as candidate cosmic ray and neutrino emitters
Predicting dataset popularity for the CMS experiment
No full textThe CMS experiment at the LHC accelerator at CERN relies on its computing infrastructure to stay at the frontier of High Energy Physics, searching for new phenomena and making discoveries. Even though computing plays a significant role in physics analysis we rarely use its data to predict the system behavior itself. A basic information about computing resources, user activities and site utilization can be really useful for improving the throughput of the system and its management. In this paper, we discuss a first CMS analysis of dataset popularity based on CMS meta-data which can be used as a model for dynamic data placement and provide the foundation of data-driven approach for the CMS computing infrastructure
Lacuna e integrazione nel restauro dei metalli archeologici: oltre la ricomposizione, verso la restituzione dell’opera. Riflessioni e proposte, tra teoria e prassi
No full textThe task of the conservator, in cooperation with the archaeologist, is to analyse archaeological material from an historical and technical standpoint in such a way that the act of conserving prior to presentation of an artefact is designed and executed for the specific artefact. This intervention must be carried out in a competent manner, i.e. the form and recognition must not be disrupted. Unfortunately, due to the corrosion of metal objects, artefacts change, which make the work of the conservator difficult. During instruction at the ISCR (Istituto Superiore per la Conservazione ed il Restauro), the possibilities for reconstructing complex metal artefacts in a collection, which shows signs of formal and aesthetic integrity, were analysed as examples. It involved filling the caesurae and defects in morphology and size. This work was aimed at restoring the integrity of the work on the formal and aesthetic side. The study also recapitulates the contribution in terms of the historical utility function of the studied objects and their technical properties
Real-time anomaly detection in data centers for log-based predictive maintenance using an evolving fuzzy-rule-based approach
No full textDetection of anomalous behaviors in data centers is crucial to predictive maintenance and data safety. With data centers, we mean any computer network that allows users to transmit and exchange data and information. In particular, we focus on the Tier-1 data center of the Italian Institute for Nuclear Physics (INFN), which supports the high-energy physics experiments at the Large Hadron Collider (LHC) in Geneva. The center provides resources and services needed for data processing, storage, analysis, and distribution. Log records in the data center is a stochastic and non-stationary phenomenon in nature. We propose a real-time approach to monitor and classify log records based on sliding time windows, and a time-varying evolving fuzzy-rule-based classification model. The most frequent log pattern according to a control chart is taken as the normal system status. We extract attributes from time windows to gradually develop and update an evolving Gaussian Fuzzy Classifier (eGFC) on the fly. The real-time anomaly monitoring system has to provide encouraging results in terms of accuracy, compactness, and real-time operation
Rates for Bayesian Estimation of Location-Scale Mixtures of Super-Smooth Densities
No full textWe consider Bayesian nonparametric density estimation with a Dirichlet process kernel mixture as a prior on the class of Lebesgue univariate densities, the emphasis being on the achievability of the error rate n^{-1/2}, up to a logarithmic factor, depending upon the kernel. We derive rates of convergence for the Bayes’ estimator of super-smooth densities that are location-scale mixtures of densities whose Fourier transforms have sub-exponential tails. We show that a nearly parametric rate is attainable in the L^1-norm, under weak assumptions on the tail decay of the true mixing distribution and the overall Dirichlet process base measure
MACROALGAL BIODIVERSITY RESPONSE UNDER A MULTIPLE STRESSOR SCENARIO
No full textBiodiversity-Ecosystem Function experimental stu- dies focusing on marine systems are few and produce contrasting outcomes. Here, we provide experimental proofs on how communities, on a natural gradient of diversity, respond under stressful conditions in inter- tidal habitats. In August 2017 a field experiment was performed in Western Sicily (Italy) in a site charac- terized by tidal pools whose biodiversity structure and composition change as a function of the distance from the low tide mark. The pools closer to the sea are more stable from a thermal and oxic point of view and characterized by high algal biodiversity. Those further from the sea are highly variable with extreme conditions and are poorer in species. We chose 12 pools – homogeneous in size and geometry – and, to know the environmental fluctuations, we measured, for 24 hours at the minute resolution, the oxygen concentration (through an oximeter) and the tem- perature (using thermos-loggers). Then, we carried out a manipulative experiment, follow the same field procedures, to investigate the effects of a climatic event (heat wave) in combination with anthropogenic stress (increased gasoline concentra- tion). We used community metabolism (oxygen consumption, mg/L) as a proxy of functioning. At the end of the treatments, we characterized the bio- diversity contained in each pool by scraping 3 quad- rats 10 x 10 cm and related it to community metabolism. No difference was observed in the metabolism between treated and controlled in high diversity pools; whilst significant differences have been found in low diversity pools for the climatic stressor. Regarding to the chemical stressor, no remarkable difference has been found. Interestingly, these results show that under the action of a disturbance, the functioning – as expressed by oxy- gen consumption – can be altered over time. The richer the community increases the ability to restore the control conditions, while the poorer pools were unable to do so
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
La tutela della riservatezza e l'identificazione dei rispondenti alle rilevazioni statistiche svolte nell'ambito del SISTAN. Rapporto finale.
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