The availability of the double-differential charged-current neutrino cross section, measured by the MiniBooNE collaboration using a carbon target, allows for a systematic comparison of nuclear effects in quasi-elastic electron and neutrino scattering. The results of our study, based on the impulse approximation scheme and a state-of-the-art model of the nuclear spectral functions, suggest that the electron cross section and the flux averaged neutrino cross sections, corresponding to the same target and comparable kinematical conditions, cannot be described within the same theoretical approach using the value of the nucleon axial mass obtained from deuterium measurements. We analyze the assumptions underlying the treatment of electron scattering data, and argue that the description of neutrino data will require a new paradigm, suitable for application to processes in which the lepton kinematics is not fully determined.PACS numbers: 25.30. Pt, 13.15.+g, 24.10.Cn The data set of Charged Current Quasi Elastic (CCQE) events recently released by the MiniBooNE collaboration [1] provides an unprecedented opportunity to carry out a systematic study of the double differential cross section of the process,integrated over the neutrino flux. Comparison between the results of theoretical calculations and data may provide valuable new information on nuclear effects, whose quantitative understanding is critical to the analysis of neutrino oscillation experiments, as well as on the elementary interaction vertex. The charged current elastic neutrino-nucleon process is described in terms of three form factors. The vector form factors F 1 (Q 2 ) and F 2 (Q 2 ) (Q 2 = −q 2 , q being the four-momentum transfer) have been precisely measured, up to large values of Q 2 , in electron-proton and electrondeuteron scattering experiments (for a recent review, see, e.g., Ref.[2]). The Q 2 -dependence of the axial form factor F A (Q 2 ), whose value at Q 2 = 0 can be extracted from neutron β-decay measurements, is generally assumed to be of dipole form and parametrized in terms of the so called axial mass M A :The world average of the measured values of the axial mass, mostly obtained using deuterium targets, turns out to be M A = 1.03 ± 0. Obviously, a fully quantitative description of the electron-scattering cross section, driven by the known vector form factors, is a prerequisite for the understanding of the axial vector contribution to the CCQE neutrino-nucleus cross section.Over the past two decades, the availability of a large body of experimental data has triggered the development of advanced theoretical descriptions of the nuclear electromagnetic response. The underlying scheme, based on nuclear many-body theory and realistic nuclear hamiltonians, relies on the premises that i) the lepton kinematics is fully determined and ii) the elementary interaction vertex can be extracted from measured proton and deuteron cross sections.The above paradigm has been successfully applied to explain the electron-nucleus cross section in a variety o...

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The COVID-19 pandemic has shown how a newly emergent communicable disease can lay considerable burden on public health. To avoid system collapse, governments have resorted to several social distancing measures. In Belgium, this included a lockdown and a following period of phased re-opening. A representative sample of Belgian adults was asked about their contact behaviour from mid-April to the beginning of August, during different stages of the intervention measures in Belgium. Use of personal protection equipment (face masks) and compliance to hygienic measures was also reported. We estimated the expected reproduction number computing the ratio of $$\hbox {R}_{0}$$ R 0 with respect to pre-pandemic data. During the first two waves (the first month) of the survey, the reduction in the average number of contacts was around 80% and was quite consistent across all age-classes. The average number of contacts increased over time, particularly for the younger age classes, still remaining significantly lower than pre-pandemic values. From the end of May to the end of July , the estimated reproduction number has a median value larger than one, although with a wide dispersion. Estimated $$\hbox {R}_{0}$$ R 0 fell below one again at the beginning of August. We have shown how a rapidly deployed survey can measure compliance to social distancing and assess its impact on COVID-19 spread. Monitoring the effectiveness of social distancing recommendations is of paramount importance to avoid further waves of COVID-19.

BackgroundSchool closure is often considered as an option to mitigate influenza epidemics because of its potential to reduce transmission in children and then in the community. The policy is still however highly debated because of controversial evidence. Moreover, the specific mechanisms leading to mitigation are not clearly identified.MethodsWe introduced a stochastic spatial age-specific metapopulation model to assess the role of holiday-associated behavioral changes and how they affect seasonal influenza dynamics. The model is applied to Belgium, parameterized with country-specific data on social mixing and travel, and calibrated to the 2008/2009 influenza season. It includes behavioral changes occurring during weekend vs. weekday, and holiday vs. school-term. Several experimental scenarios are explored to identify the relevant social and behavioral mechanisms.ResultsStochastic numerical simulations show that holidays considerably delay the peak of the season and mitigate its impact. Changes in mixing patterns are responsible for the observed effects, whereas changes in travel behavior do not alter the epidemic. Weekends are important in slowing down the season by periodically dampening transmission. Christmas holidays have the largest impact on the epidemic, however later school breaks may help in reducing the epidemic size, stressing the importance of considering the full calendar. An extension of the Christmas holiday of 1 week may further mitigate the epidemic.ConclusionChanges in the way individuals establish contacts during holidays are the key ingredient explaining the mitigating effect of regular school closure. Our findings highlight the need to quantify these changes in different demographic and epidemic contexts in order to provide accurate and reliable evaluations of closure effectiveness. They also suggest strategic policies in the distribution of holiday periods to minimize the epidemic impact.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-017-2934-3) contains supplementary material, which is available to authorized users.

Social contact data are increasingly being used to inform models for infectious disease spread with the aim of guiding effective policies on disease prevention and control. In this paper, we undertake a systematic review of the study design, statistical analyses and outcomes of the many social contact surveys that have been published. Our primary focus is to identify the designs that have worked best and the most important determinants and to highlight the most robust findings. Two publicly accessible online databases were systematically searched for articles regarding social contact surveys. PRISMA guidelines were followed as closely as possible. In total, 64 social contact surveys were identified. These surveys were conducted in 24 countries, and more than 80% of the surveys were conducted in high-income countries. Study settings included general population (58%), schools/universities (37%) and health care/conference/research institutes (5%). The majority of studies did not focus on a specific age group (38%), whereas others focused on adults (32%) or children (19%). Retrospective and prospective designs were used mostly (45% and 41% of the surveys, respectively) with 6% using both for comparison purposes. The definition of a contact varied among surveys, e.g. a non-physical contact may require conversation, 1. CC-BY-NC-ND 4.0 International license It is made available under a (which was not peer-reviewed) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity.The copyright holder for this preprint . http://dx.doi.org/10.1101/292235 doi: bioRxiv preprint first posted online Mar. 31, 2018; close proximity or both. Age, time schedule (e.g., weekday/weekend) and household size were identified as relevant determinants for contact pattern across a large number of studies. The surveys present a wide range of study designs. Throughout, we found that the overall contact patterns were remarkably robust for the study details. By considering the most common approach in each aspect of design (e.g., sampling schemes, data collection, definition of contact), we could identify a common practice approach that can be used to facilitate comparison between studies and for benchmarking future studies.