1,721,091 research outputs found
Epidemic spreading in an expanded parameter space: the supercritical scaling laws and subcritical metastable phases
Full text linkWhile the mathematical laws of uncontrolled epidemic spreading are well known, the statistical physics of coronavirus epidemics with containment measures is currently lacking. The modelling of available data of the first wave of the Covid-19 pandemic in 2020 over 230 days, in different countries representative of different containment policies is relevant to quantify the efficiency of these policies to face the containment of any successive wave. At this aim we have built a 3D phase diagram tracking the simultaneous evolution and the interplay of the doubling time, T (d), and the reproductive number, R (t) measured using the methodological definition used by the Robert Koch Institute. In this expanded parameter space three different main phases, supercritical, critical and subcritical are identified. Moreover, we have found that in the supercritical regime with R (t) > 1 the doubling time is smaller than 40 days. In this phase we have established the power law relation between T (d) and (R (t) - 1)(-nu) with the exponent nu depending on the definition of reproductive number. In the subcritical regime where R (t) < 1 and T (d) > 100 days, we have identified arrested metastable phases where T (d) is nearly constant
Efficiency of COVID-19 mobile contact tracing containment by measuring time-dependent doubling time
Full text linkThe COVID-19 epidemic of the novel coronavirus (severe acute respiratory syndrome SARS-CoV-2) has spread around the world. While different containment policies using non-pharmaceutical interventions have been applied, their efficiencies are not known quantitatively. We show that the doubling timeT(d)(t) with the successs factor, the characteristic time of the exponential growth ofT(d)(t) in the arrested regime, is a reliable tool for early predictions of epidemic spread time evolution and provides a quantitative measure of the success of different containment measures. The efficiency of the containment policylockdown case finding mobile tracing(LFT) using mandatory mobile contact tracing is much higher than that of thelockdown stop and gopolicy proposed by the Imperial College team in London. A very lowsfactor was reached by the LFT policy, giving the shortest time width of the positive case curve and the lowest number of fatalities. The LFT policy was able to reduce the number of fatalities by a factor of 100 in the first 100 d of the COVID-19 epidemic, reduce the time width of the COVID-19 pandemic curve by a factor 2.5, and rapidly stop new outbreaks and thereby avoid a second wave to date
Sars-Cov2 world pandemic recurrent waves controlled by variants evolution and vaccination campaign
Full text linkWhile understanding the time evolution of Covid-19 pandemic is needed to plan economics and tune sanitary policies, a quantitative information of the recurrent epidemic waves is elusive. This work describes a statistical physics study of the subsequent waves in the epidemic spreading of Covid-19 and disclose the frequency components of the epidemic waves pattern over two years in United States, United Kingdom and Japan. These countries have been taken as representative cases of different containment policies such as "Mitigation" (USA and UK) and "Zero Covid" (Japan) policies. The supercritical phases in spreading have been identified by intervals with RIC-index > 0. We have used the wavelet transform of infection and fatality waves to get the spectral analysis showing a dominant component around 130 days. Data of the world dynamic clearly indicates also the crossover to a different phase due to the enforcement of vaccination campaign. In Japan and United Kingdom, we observed the emergence in the infection waves of a long period component (~ 170 days) during vaccination campaign. These results indicate slowing down of the epidemic spreading dynamics due to the vaccination campaign. Finally, we find an intrinsic difference between infection and fatality waves pointing to a non-trivial variation of the lethality due to different gene variants
IKNO, a user facility for coherent terahertz and UV synchrotron radiation
Full text linkIKNO (Innovation and KNOwledge) is a proposal for a multi-user facility based
on an electron storage ring optimized for the generation of coherent
synchrotron radiation (CSR) in the terahertz frequency range, and of broadband
incoherent synchrotron radiation ranging from the IR to the VUV. IKNO can
be operated in an ultra-stable CSR mode with photon flux in the terahertz
frequency region up to nine orders of magnitude higher than in existing thirdgeneration
light sources. Simultaneously to the CSR operation, broadband
incoherent synchrotron radiation up to VUV frequencies is available at the
beamline ports. The main characteristics of the IKNO storage and its
performance in terms of CSR and incoherent synchrotron radiation are
described in this paper. The proposed location for the infrastructure facility is
Sardinia, Italy
Analysis of structural changes at interfaces of dental tissues by EDIXS and FTIR
Full text linkFil: Sánchez, Héctor Jorge. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Sánchez, Héctor Jorge. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Leani, Juan Jose. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Leani, Juan Jose. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Robledo, José Ignacio. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Grenón, Miriam Silvina. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Periodoncia A; Argentina.Fil: Marcelli, Augusto Claudio. Laboratori Nazionali di Frascati; Italia.Fil: Migliori, Alessandro. International Atomic Energy Agency; Austria.Fil: Yuying Liu, Huijuan Wang. National Synchrotron Radiation Laboratory; China.Fil: Qi, Zeming, Huijuan Wang. National Synchrotron Radiation Laboratory; China.Participación en calidad de co-autora del trabajo: ?Analysis of structural changes at interfaces of dental tissues by EDIXS and FTIR?, H.J. Sánchez, J.J. Leani, J.I. Robledo, M. Grenón, A. Marcelli, A. Migliori, W. Yuying and Zeming Qi, EUROPEAN CONFERENCE ON X-RAY SPECTROMETRY (EXRS 2022), 2022, Brudge, BelgiumFil: Sánchez, Héctor Jorge. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Sánchez, Héctor Jorge. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Leani, Juan Jose. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales; Argentina.Fil: Leani, Juan Jose. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Robledo, José Ignacio. Consejo Nacional de Investigaciones y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Grenón, Miriam Silvina. Universidad Nacional de Córdoba. Facultad de Odontología. Cátedra de Periodoncia A; Argentina.Fil: Marcelli, Augusto Claudio. Laboratori Nazionali di Frascati; Italia.Fil: Migliori, Alessandro. International Atomic Energy Agency; Austria.Fil: Yuying Liu, Huijuan Wang. National Synchrotron Radiation Laboratory; China.Fil: Qi, Zeming, Huijuan Wang. National Synchrotron Radiation Laboratory; China.Odontología, Medicina y Cirugía Ora
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Morphological, electronic, and magnetic properties of multicomponent cobalt oxide nanoparticles synthesized by high temperature arc plasma
Full text linkMany technological applications demand large amount of nanoparticles with well-defined properties, which is feasible only by using large-scale production methods. In this framework, we have performed structural and local geometric investigations of cobalt oxide nanoparticles synthesized by high temperature arc plasma route in helium and in air atmosphere with different arc currents, a competitive and low cost technological approach to synthesize large quantity of different types of nanoparticles. The complex scenario of phase fraction, shape, size distribution and hysteresis loop features of high temperature arc plasma synthesis of nanoparticles can be determined by the arc current and the selected gas. X-ray diffraction patterns reveal a multicomponent phase formation containing cubic cobaltous oxide (CoO), cobaltic oxide (Co3O4) and metallic cobalt phases. The synthesis of different phases is confirmed by x-ray absorption spectroscopy measurements at the Co K-edge. Both extended x-ray absorption fine structure and x-ray absorption near edge structure analyses show the presence of metallic nanoparticles in He ambient at high arc current. Moreover, high-resolution transmission electron microscopy images and magnetic hysteresis loop measurements show that the mean particle size increases and the coercivity decreases with increasing arc current in air ambient due to the intense particle–particle interaction. At variance, in He ambient synthesized samples due to the high quenching rate and the high thermal conductivity, a multi-domain formation in which the nanoparticles' crystalline fraction decreases and a fluctuating coercivity due to core–shell structure is observed
Characterization of volatile organic compounds (VOCs) in their liquid-phase by terahertz time-domain spectroscopy
Full text linkIn this work the terahertz spectra of benzene, toluene, p-xylene and styrene–four volatile organic compounds (VOCs) of interest in environmental pollution studies–have been measured in their liquid phase at room temperature using terahertz time-domain spectroscopy (THz-TDS). Their frequency-dependent refractive index and absorption coefficient have been extracted and analyzed in the spectral range from 0.2 to 2.5 THz. The optical properties of bi-component VOCs mixtures have also been investigated and described in terms of a linear combination of pure VOCs optical components
Preliminary synchrotron radiation characterization of first multilayer mirrors for the soft X-ray water window
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