Chaotic motion of charged particles in toroidal magnetic configurations

We study the motion of a charged particle in a tokamak magnetic field and discuss its chaotic nature. Contrary to most of recent studies, we do not make any assumption on any constant of the motion and solve numerically the cyclotron gyration using Hamiltonian formalism. We take advantage of a symplectic integrator allowing us to make long-time simulations. First considering an idealized magnetic configuration, we add a non generic perturbation corresponding to a magnetic ripple, breaking one of the invariant of the motion. Chaotic motion is then observed and opens questions about the link between chaos of magnetic field lines and chaos of particle trajectories. Second, we return to a axi-symmetric configuration and tune the safety factor (magnetic configuration) in order to recover chaotic motion. In this last setting with two constants of the motion, the presence of chaos implies that no third global constant exists, we highlight this fact by looking at variations of the first order of the magnetic moment in this chaotic setting. We are facing a mixed phase space with both regular and chaotic regions and point out the difficulties in performing a global reduction such as gyrokinetics

The threshold level of urinary cadmium associated with increased urinary excretion of retinol-binding protein and β2-microglobulin: a re-assessment in a large cohort of nickel-cadmium battery workers

OBJECTIVE: To evaluate the threshold value of urinary cadmium (CdU) for renal dysfunction on the basis of relationships unconfounded by protein degradation, diuresis and the renal effects associated with chronic smoking. Methods We studied 599 workers (451 men, mean age 45.4 years) who were employed in four nickel-cadmium battery plants for 18.8 years on average. After adjustment for covariates by multiple regression, the CdU threshold values for increased concentrations of retinol-binding protein (RBPU) and b(2)-microglobulin (b(2)-mU) were assessed by logistic regression and benchmark dose analyses using as referents workers with CdU10, respectively. The benchmark dose (BMD5) and the benchmark dose lower limit (BMDL5) for a 5% excess in the background prevalence of abnormal RBPU and b(2)-mU were estimated at 5.1/3.0 and 9.6/5.9. When excluding ever smokers, odds for abnormal RBPU and b(2)-mU were both increased only among workers with CdU>10 (OR, 21.8, 95% CI, 6.4-74.4 and OR, 15.1, 95% CI, 3.6-63.1, respectively). In never smokers, these BMD5/BMDL5 of CdU were estimated at 12.6/6.6 and 12.2/5.5 while in ever smokers they were 6.2/4.9 and 4.3/3.5. Conclusions On the basis of associations undistorted by smoking and adjusted for covariates, the BMDL5 of CdU for low-molecular-weight proteinuria induced by occupational exposure to Cd can be reliably estimated between 5.5 and 6.6 μg/g creatinine

On the relationship between residual zonal flows and bump-on tail saturated instabilities

A connection is established between two classical problems: the non linear saturation of a bump-on tail instability in collisionless regime, and the decay of a zonal flow towards a finite amplitude residual. Reasons for this connection are given and commented

The French EO high spatial resolution hyperspectral dual mission - an update

More than 25 years of airborne imaging spectroscopy and spaceborne sensors such as Hyperion [1] or HICO [2] have clearly demonstrated the ability of such a remote sensing technique to produce value added information regarding surface composition and physical properties for a large variety of applications [3]. Scheduled missions such as EnMAP [4], HISUI [5] or PRISMA [6] prove the increased interest of the scientific community for such a type of remote sensing data. In France, after gathering a group of Science and Defence users of imaging spectrometry data (Groupe de Synthèse Hyperspectral, GSH [7]) to establish an up-to-date review of possible applications, define instrument specifications required for accurate, quantitative retrieval of diagnostic parameters, and identify fields of application where imaging spectrometry is a major contribution, CNES (French Space Agency) decided a pre-phase A study for an hyperspectral mission concept called HYPXIM (HYPerspectral-X IMagery), the main fields of applications of which were to be vegetation, coastal and inland waters, geosciences, urban environment, atmospheric sciences, cryosphere and Defence. During this pre-phase A, the feasibility of such a platform was evaluated, based on specific studies supported by Defence and a more accurate definition of reference radiances and instrument characteristics. Results also pointed to applications where high spatial resolution was necessary and would not be covered by the other foreseen hyperspectral missions. For example, in the case of ecosystem studies, it is generally agreed that many model variables and processes are not accurately represented and that upcoming sensors with improved spatial and spectral capabilities, such as higher resolution imaging spectrometers, are needed to further improve the quality and accuracy of model variables [8, 9]. The growing interest for urban environment related applications also emphasized the need for an increased spatial resolution [10, 11]. Finally, short revisit time is an issue for security and Defense as well as crisis monitoring. Table 1 summarizes the Science and Defence mission requirements at the end of pre-phase A. Two instrument designs were proposed by the industry (EADS-Astrium and Thales Alenia Space) based on these new requirements [12]: HYPXIM-Challenging, on a micro-satellite platform, with a 15 m pixel and HYPXIM-Performance, on a mini-satellite platform, with a 8 m pixel, and possible TIR hyperspectral capabilities. Both scenarios included a PAN camera with a 1.85 m pixel. Platform agility would allow for “on-event mode” with a 3-day revisit time. CNES decided to select HYPXIM-Performance, the system providing a higher spatial resolution (pixel ≤ 8 m, [13, 14]), but without TIR capabilities, for a phase A study [15]. This phase A was to start at the beginning of 2013 but is currently stopped due to budget constraints. An important part of the activities has been focusing on getting the French community more involved through various surveys and workshops in preparation for the CNES prospective meeting, an important step for the future of the mission. During this prospective meeting, which took place last March, decision was taken to keep HYPXIM alive as a mid-term (2020-2025) mission. The attendance at the recent workshop organized by the SFPT-GH (Société Française de Photogrammétrie et Télédétection, Groupe Hyperspectral) which gathered more than 90 participants from various field of application, including the industry (see http://www.sfpt.fr/hyperspectral for more details), demonstrates the interest and support of the French scientific community for a high spatial resolution imaging spectrometry mission

Using rapid point-of-care tests to inform antibiotic choice to mitigate drug resistance in gonorrhoea

Background: The first cases of extensively drug resistant gonorrhoea were recorded in the United Kingdom in 2018. There is a public health need for strategies on how to deploy existing and novel antibiotics to minimise the risk of resistance development. As rapid point-of-care tests (POCTs) to predict susceptibility are coming to clinical use, coupling the introduction of an antibiotic with diagnostics that can slow resistance emergence may offer a novel paradigm for maximising antibiotic benefits. Gepotidacin is a novel antibiotic with known resistance and resistance-predisposing mutations. In particular, a mutation that confers resistance to ciprofloxacin acts as the ‘stepping-stone’ mutation to gepotidacin resistance. Aim: To investigate how POCTs detecting Neisseria gonorrhoeae resistance mutations for ciprofloxacin and gepotidacin can be used to minimise the risk of resistance development to gepotidacin. Methods: We use individual-based stochastic simulations to formally investigate the aim. Results: The level of testing needed to reduce the risk of resistance development depends on the mutation rate under treatment and the prevalence of stepping-stone mutations. A POCT is most effective if the mutation rate under antibiotic treatment is no more than two orders of magnitude above the mutation rate without treatment and the prevalence of stepping-stone mutations is 1–13%. Conclusion: Mutation frequencies and rates should be considered when estimating the POCT usage required to reduce the risk of resistance development in a given population. Molecular POCTs for resistance mutations and stepping-stone mutations to resistance are likely to become important tools in antibiotic stewardship

Quantitative structural and textural assessment of laminar pyrocarbons through Raman spectroscopy, electron diffraction and few other techniques

In pyrocarbon materials, the width of the Raman D band (FWHMD) is very sensitive to low energy structural defects (e.g., disorientations of the graphene layers). The correlation between the two parameters, FWHMD and OA (as derived from selected area electron diffraction: SAED), has allowed to differentiate various pyrocarbons unambiguously. Furthermore, the optical properties of pyrocarbons, i.e., the extinction angle, the optical phase shift and the ordinary and extraordinary reflectance, have been accurately determined at 550 nm by means of the extinction curves method. These results are completed by in-plane and out-of-plane dielectric constant measurements by angular resolved EELS. Moreover, the hybridization degree of the carbon atoms has been assessed by the same technique. About 80% of the carbon atoms of the pyrocarbons have a sp2 hybridization. The lack of pure sp2 carbon atoms, as compared to graphite, might be explained by the presence of sp3-like line defects.Comment: Xavier Bourrat : Present Address = ISTO - CNRS-Universit\'e d'Orl\'ean

Telemedicina: vantagens e desafios do exercício médico à distância

Telemedicina em sentido amplo pode ser definida como o uso das tecnologias de informação e comunicação na saúde, ofertando serviços ligados aos cuidados com a saúde, sobretudo nos casos em que a distância é um fator crítico. A proposta da implantação de um sistema de telemedicina quebra barreiras geográficas e socioeconômicas ao dar acesso à população mais carente. Nesse caso, a telemedicina passa a ser baseada na comunidade e nos cuidados com a saúde ao proporcionar melhor aderência ao tratamento de morbidades e um acompanhamento e controle de variáveis fisiológicas. Descrever as vantagens e os desafios do uso da telemedicina no exercício médico. O presente estudo trata-se de uma revisão integrativa de literatura, cujos artigos originais foram pesquisados em bases de dados, como Scientific Electronic Library Online (SciELO), Google Acadêmico, ScienceDirect e Thieme Connect, a partir dos Descritores em Ciência e Saúde (DESC): “telemedicina”, “teleconsulta” e “coronavírus”, sendo selecionados onze artigos publicados a partir de 2016. A telemedicina é democrática em relação aos serviços de saúde, de modo que seu potencial abrangente permite a ampliação das políticas de saúde públicas, como também a melhora no diagnóstico e terapia aos pacientes. Apesar do avanço da telemedicina os desafios que dificultam o seu desenvolvimento são: falta de padronização da telemedicina, inviabilização do exame físico, mudanças na interação médico-paciente, cultura social resistente à telemedicina, falta de infraestrutura abrangente que permite a democratização da telemedicina, conflitos com a ética médica e déficit de expertise técnica. No atual cenário de pandemia da COVID-19, a telemedicina evidenciou suas vantagens nessa forma de exercício da área médica com o paciente. Dentre as vantagens dessa nova forma de atuação da área da saúde se destacam: diminuição da superlotação dos sistemas de saúde presenciais, não sobrecarga dos profissionais de saúde, otimização dos atendimentos aos pacientes, diminuição do perigo aos pacientes de risco à exposição hospitalar e unidades de saúde com alto potencial infeccioso, atenção à saúde à regiões geograficamente afastadas, redução de custos de  serviços à saúde, assistência pós-operatório elaborada aos pacientes e acompanhamento terapêutico otimizado qualitativamente aos pacientes. Apesar de ainda encontrar dificuldades técnicas como a padronização da teleconsulta e resistência social sobre tal forma de atendimento, esse atendimento inovador terá maior aceitação a partir do momento em que se puser em prática de maneira extensiva a telemedicina, esta que é o futuro dos atendimentos médicos, principalmente em momentos de crise sanitária como a atual pandemia do novo coronavírus. Tal prática traz inúmeras melhorias para a equipe médica e para os pacientes, e também implica em aceitabilidade crescente para os públicos que são abrangidos pela técnica

Telemedicina no contexto da pandemia da COVID-19: vantagens e perspectivas

A telemedicina é o conjunto de serviços clínicos e educacionais por meio do uso de tecnologias da informação e comunicação na área da saúde. No contexto da pandemia pela COVID-19, a teleconsulta proporciona boa segurança para os pacientes e profissionais nos estabelecimentos de saúde. Essa modalidade de atendimento destaca-se atualmente e apresenta-se em expansão para outros contextos em que dificuldades sociogeográficas são um empecilho para o acesso médico de qualidade. Descrever as vantagens e as perspectivas do exercício médico nas consultas à distância no contexto de isolamento social promovido pela pandemia do novo coronavírus. O presente estudo trata-se de uma revisão integrativa de literatura, cujos artigos originais foram pesquisados em bases de dados, como Scientific Electronic Library Online (SciELO), Google Acadêmico, Science Direct e Thieme Connect, a partir dos Descritores em Ciência e Saúde (DeSC): “telemedicina”, “teleconsulta” e “COVID-19”, sendo selecionados sete artigos publicados a partir de Janeiro de 2020. Essa modalidade de atendimento tem sido um aliado para a ampliação dos cuidados em saúde, superando a barreira da distância e promovendo uma democratização do acesso aos serviços de saúde para a população geral. Outras vantagens são economia de tempo e dinheiro, acesso rápido a especialistas em casos de emergência, cooperação e integração de pesquisadores com o compartilhamento de registros clínicos, maior qualidade dos programas educacionais para médicos e residentes fora de zonas de centros especializados e diminuição da ida a hospitais lotados e com riscos de infecções. Este último benefício apresenta alta relevância no atual contexto da pandemia da COVID-19, uma vez que medidas, como o distanciamento social, são fundamentais para a desaceleração da propagação do vírus. Isso contribui para a proteção dos pacientes pertencentes a grupos de riscos e reduz o pico de necessidade por assistência médica em hospitais e UTIs. Sendo assim, a telemedicina se tornou uma ferramenta indispensável para reduzir a circulação de pessoas nos estabelecimentos de saúde, lentificar a propagação da doença, além de liberar leitos e vagas de atendimento hospitalar. Ademais, torna-se uma opção para o atendimento médico de portadores de comorbidades preexistentes que necessitam de suporte presencial. As pesquisas mostram que a telemedicina representa uma alternativa eficaz no cenário atual e que os pacientes valorizam o atendimento remoto, o que pode ser uma grande oportunidade de ampliar os sistemas de apoio à saúde em outras áreas médicas. A telemedicina apresenta-se como uma excelente ferramenta para o atendimento médico e encontra-se em destaque no combate ao coronavírus. O bom uso da tecnologia no atendimento remoto representa uma nova alternativa no cuidado médico. Vislumbra-se a potencial aceitação pública da telemedicina nacional e mundialmente, fortalecendo os sistemas de saúde

Interleukin-18 produced by bone marrow- derived stromal cells supports T-cell acute leukaemia progression

International audienceDevelopment of novel therapies is critical for T-cell acute leukae-mia (T-ALL). Here, we investigated the effect of inhibiting the MAPK/MEK/ERK pathway on T-ALL cell growth. Unexpectedly, MEK inhibitors (MEKi) enhanced growth of 70% of human T-ALL cell samples cultured on stromal cells independently of NOTCH activa-tion and maintained their ability to propagate in vivo. Similar results were obtained when T-ALL cells were cultured with ERK1/ 2-knockdown stromal cells or with conditioned medium from MEKi-treated stromal cells. Microarray analysis identified interleu-kin 18 (IL-18) as transcriptionally up-regulated in MEKi-treated MS5 cells. Recombinant IL-18 promoted T-ALL growth in vitro, whereas the loss of function of IL-18 receptor in T-ALL blast cells decreased blast proliferation in vitro and in NSG mice. The NFKB pathway that is downstream to IL-18R was activated by IL-18 in blast cells. IL-18 circulating levels were increased in T-ALL-xeno-grafted mice and also in T-ALL patients in comparison with controls. This study uncovers a novel role of the pro-inflammatory cytokine IL-18 and outlines the microenvironment involvement in human T-ALL development