Measurement of the Solar Neutrino Capture Rate by the Russian-American Gallium Solar Neutrino Experiment During One Half of the 22-Year Cycle of Solar Activity

We present the results of measurements of the solar neutrino capture rate in gallium metal by the Russian-American Gallium Experiment SAGE during slightly more than half of a 22-year cycle of solar activity. Combined analysis of the data of 92 runs during the 12-year period January 1990 through December 2001 gives a capture rate of solar neutrinos with energy more than 233 keV of 70.8 +5.3/-5.2 (stat.) +3.7/-3.2 (syst.) SNU. This represents only slightly more than half of the predicted standard solar model rate of 128 SNU. We give the results of new runs beginning in April 1998 and the results of combined analysis of all runs since 1990 during yearly, monthly, and bimonthly periods. Using a simple analysis of the SAGE results combined with those from all other solar neutrino experiments, we estimate the electron neutrino pp flux that reaches the Earth to be (4.6 +/- 1.1) E10/(cm^2-s). Assuming that neutrinos oscillate to active flavors the pp neutrino flux emitted in the solar fusion reaction is approximately (7.7 +/- 1.8) E10/(cm^2-s), in agreement with the standard solar model calculation of (5.95 +/- 0.06) E10/(cm^2-s).Comment: English translation of article submitted to Russian journal Zh. Eksp. Teor. Fiz. (JETP); 12 pages, 5 figures. V2: Added winter-summer difference and 2 reference

Solar neutrinos, helioseismology and the solar internal dynamics

Neutrinos are fundamental particles ubiquitous in the Universe. Their properties remain elusive despite more than 50 years of intense research activity. In this review we remind the reader of the noticeable properties of these particles and of the stakes of the solar neutrino puzzle. The Standard Solar Model triggered persistent efforts in fundamental Physics to predict the solar neutrino fluxes, and its constantly evolving predictions have been regularly compared to the detected neutrino signals. Anticipating that this standard model could not reproduce the internal solar dynamics, a SEismic Solar Model was developed which enriched theoretical neutrino flux predictions with in situ observation of acoustic waves propagating in the Sun. This review reminds the historical steps, from the pioneering Homestake detection, the GALLEX- SAGE captures of the first pp neutrinos and emphasizes the importance of the Superkamiokande and SNO detectors to demonstrate that the solar-emitted electronic neutrinos are partially transformed into other neutrino flavors before reaching the Earth. The success of BOREXINO in detecting the 7 Be neutrino signal justifies the building of a new generation of detectors to measure the entire solar neutrino spectrum. A coherent picture emerged from neutrino physics and helioseismology. Today, new paradigms take shape: determining the masses of neutrinos and the research on the Sun is focusing on the dynamical aspects and on signature of dark matter. The third part of the review is dedicated to this prospect. The understanding of the crucial role of both rotation and magnetism in solar physics benefit from SoHO, SDO, and PICARD space observations. For now, the particle and stellar challenges seem decoupled, but this is only a superficial appearance. The development of asteroseismology shows the far-reaching impact of Neutrino and Stellar Astronomy.Comment: 60 pages, 12 figures Invited review in press in Report on Progress in Physic

A mass-structured individual-based model of the chemostat: convergence and simulation

We propose a model of chemostat where the bacterial population is individually-based, each bacterium is explicitly represented and has a mass evolving continuously over time. The substrate concentration is represented as a conventional ordinary differential equation. These two components are coupled with the bacterial consumption. Mechanisms acting on the bacteria are explicitly described (growth, division and up-take). Bacteria interact via consumption. We set the exact Monte Carlo simulation algorithm of this model and its mathematical representation as a stochastic process. We prove the convergence of this process to the solution of an integro-differential equation when the population size tends to infinity. Finally, we propose several numerical simulations

Internationalisation of higher education in South Korea: Reality, rhetoric, and disparity in academic culture and identities

This article may not exactly replicate the final version published in the Australian Journal of Education. It is not a copy of the record.The central theme of this paper is contradictions: the ways in which official agendas of internationalisation in higher education and academic identity are disturbed by the principles of inclusion and exclusion in the local context of university academic culture. The paper takes the case of South Korea to show how the national policies for the internationalisation of higher education are translated into local cultural practice inside academe. The paper examines specifically (i) what are the ‘positions’ of foreign and female academics in the specific national university context; (ii) how are they constructed by official policies of internationalisation, and (iii) how are they experienced by individuals to form new reflexive identities? Drawing from biographic notes, the paper offers an illustrative analysis of the positioned and positional identities of foreign and female academics and the boundaries of inclusion and exclusion drawn around their identities. The paper is an exploratory one, aimed at future research agendas for a larger theoretical study on internationally mobile academics in different social contexts

Trusted Noise in Continuous-Variable Quantum Key Distribution: a Threat and a Defense

We address the role of the phase-insensitive trusted preparation and detection noise in the security of a continuous-variable quantum key distribution, considering the Gaussian protocols on the basis of coherent and squeezed states and studying them in the conditions of Gaussian lossy and noisy channels. The influence of such a noise on the security of Gaussian quantum cryptography can be crucial, even despite the fact that a noise is trusted, due to a strongly nonlinear behavior of the quantum entropies involved in the security analysis. We recapitulate the known effect of the preparation noise in both direct and reverse-reconciliation protocols, as well as the detection noise in the reverse-reconciliation scenario. As a new result, we show the negative role of the trusted detection noise in the direct-reconciliation scheme. We also describe the role of the trusted preparation or detection noise added at the reference side of the protocols in improving the robustness of the protocols to the channel noise, confirming the positive effect for the coherent-state reverse-reconciliation protocol. Finally, we address the combined effect of trusted noise added both in the source and the detector.Comment: 25 pages, 9 figure