Turbulent viscosity in clumpy accretion disks II supernova driven turbulence in the Galaxy

An analytical model for a turbulent clumpy gas disk is presented where turbulence is maintained by the energy input due to supernovae. Expressions for the disk parameters, global filling factors, molecular fractions, and star formation rates are given as functions of the Toomre parameter $Q$, the ratio between the cloud size and the turbulent driving length scale $\delta$, the mass accretion rate within the disk $\dot{M}$, the constant of molecule formation $\alpha$, the disk radius, the angular velocity, and its radial derivative. Two different cases are investigated: a dominating stellar disk and a self-gravitating gas disk in $z$ direction. The turbulent driving wavelength is determined in a first approach by energy flux conservation, i.e. the supernovae energy input is transported by turbulence to smaller scales where it is dissipated. The results are compared to those of a fully gravitational model. For Q=1 and $\delta=1$ both models are consistent with each other. In a second approach the driving length scale is directly determined by the size of supernovae remnants. Both models are applied to the Galaxy and can reproduce its integrated and local gas properties. The influence of thermal and magnetic pressure on the disk structure is investigated. We infer $Q \sim 1$ and $\dot{M} \sim 0.05 - 0.1 M_{\odot} yr ^{-1}$ for the Galaxy.Comment: 15 pages with 10 figures. Accepted for publication in A&

Semi-inclusive charged-current neutrino-nucleus cross sections in the relativistic plane wave impulse approximation

Neutrino-nucleus quasielastic scattering is studied in the plane wave impulse approximation for three nuclear models: the relativistic Fermi gas (RFG), the independent-particle shell model (IPSM) and the natural orbitals (NO) model with Lorentzian dependence of the excitation energy. A complete study of the kinematics of the semi-inclusive process and the associated cross sections are presented and discussed for 40 Ar and 12 C. Inclusive cross sections are also obtained by integrating the semi-inclusive expressions over the outgoing hadron. Results are consistent with previous studies restricted to the inclusive channel. In particular, a comparison with the analytical results for the RFG model is performed. Explicit expressions for the hadronic tensor and the 10 semi-inclusive nuclear responses are given. Theoretical predictions are compared with semi-inclusive experimental data from T2K experiment.Comment: 55 pages, 22 figures, submitted to Physical Review

Use of GoFundMe® to crowdfund complementary and alternative medicine treatments for cancer.

PurposeComplementary and alternative medicine (CAM) use is common amongst cancer patients. However, there is growing concern about its safety and efficacy. Online crowdfunding campaigns represent a unique avenue to understand the cancer patient's perspective for using CAM or declining conventional cancer therapy (CCT).MethodsFive hundred GoFundMe campaigns from 2012 to 2019 detailing financial need for cancer treatment were randomly selected and reviewed for endorsement of CAM use, reasons for using CAM, and reasons for declining CCT. Descriptive statistics were used to compare patient and campaign characteristics between 250 CAM users and 250 non-CAM users.ResultsCompared to non-CAM users, CAM users were more likely to be female (70% vs. 54%, p < 0.01), to report more stage IV cancer (54% vs. 12%, p < 0.01), and to have a history of delayed, missed, or misdiagnosis (10% vs. 4%, p < 0.01). Reasons for using CAM include endorsing curative/therapeutic effects 212 (85%), pain/stress reduction 137 (55%), and dissatisfaction with current or past medical treatment options 105 (42%). 87 (35%) CAM users that declined CCT reported that they wanted to try to fight off cancer using CAM first 57 (61%), that CCT was too "toxic" to the body 39 (42%), and cancer was already too advanced, so that CCT would be futile or too aggressive 25 (27%).ConclusionCancer patients on GoFundMe using CAM highly value quality of life, comfort, and autonomy. Physicians should educate themselves on CAM to set realistic expectations and provide comprehensive counseling of the risks and benefits of CAM usage to patients who choose to use CAM to either augment or completely replace CCT

Notas sobre planejamento de assistência médica na América Latina e no Caribe

Attention is called to the fact that the efforts to improve health of populations in Latin America have generally failed. The inequality in the distribution of ill-health is great. The authors accept the fact that the lack of resources available to the health sector may be a restriction towards the improvement of the situation, but they argue that a much more important issue is the misuse of such resources and their maldistribution within the health sector. The lack of integration and coordination between the health services, the conflict of public and private health systems, the under-utilization of existing services and the gap between planning and real implementation are discussed.Chama-se a atenção para o fato de que os esforços para a melhoria da saúde das populações da América Latina, geralmente têm falhado. A desigualdade na distribuição de saúde é grande. Aceita-se o fato de que a falta de recursos disponíveis para o setor saúde pode ser empecilho para a melhoria da situação, mas argumenta-se que um fator muito mais importante é o uso indevido de tais recursos e sua má distribuição dentro do setor saúde. São discutidas as faltas de integração e coordenação dos serviços de saúde, o conflito entre sistemas público e privado de saúde, a sub-utilização dos serviços existentes, o distanciamento entre o planejamento e a sua real implementação

Cross-linkers both drive and brake cytoskeletal remodeling and furrowing in cytokinesis.

Cell shape changes such as cytokinesis are driven by the actomyosin contractile cytoskeleton. The molecular rearrangements that bring about contractility in nonmuscle cells are currently debated. Specifically, both filament sliding by myosin motors, as well as cytoskeletal cross-linking by myosins and nonmotor cross-linkers, are thought to promote contractility. Here we examined how the abundance of motor and nonmotor cross-linkers affects the speed of cytokinetic furrowing. We built a minimal model to simulate contractile dynamics in the Caenorhabditis elegans zygote cytokinetic ring. This model predicted that intermediate levels of nonmotor cross-linkers are ideal for contractility; in vivo, intermediate levels of the scaffold protein anillin allowed maximal contraction speed. Our model also demonstrated a nonlinear relationship between the abundance of motor ensembles and contraction speed. In vivo, thorough depletion of nonmuscle myosin II delayed furrow initiation, slowed F-actin alignment, and reduced maximum contraction speed, but partial depletion allowed faster-than-expected kinetics. Thus, cytokinetic ring closure is promoted by moderate levels of both motor and nonmotor cross-linkers but attenuated by an over-abundance of motor and nonmotor cross-linkers. Together, our findings extend the growing appreciation for the roles of cross-linkers in cytokinesis and reveal that they not only drive but also brake cytoskeletal remodeling

Geographical range in liverworts: does sex really matter?

AimWhy some species exhibit larger geographical ranges than others remains a fundamental, but largely unanswered, question in ecology and biogeography. In plants, a relationship between range size and mating system was proposed over a century ago and subsequently formalized in Baker's Law. Here, we take advantage of the extensive variation in sexual systems of liverworts to test the hypothesis that dioecious species compensate for limited fertilization by producing vegetative propagules more commonly than monoecious species. As spores are assumed to contribute to random long-distance dispersal, whereas vegetative propagules contribute to colony maintenance and frequent short-distance dispersal, we further test the hypothesis that monoecious species exhibit larger geographical ranges than dioecious ones.LocationWorldwide.MethodsWe used comparative phylogenetic methods to assess the correlation between range size and life history traits related to dispersal, including mating systems, spore size and production of specialized vegetative propagules.ResultsNo significant correlation was found between dioecy and production of vegetative propagules. However, production of vegetative propagules is correlated with the size of geographical ranges across the liverwort tree of life, whereas sexuality and spores size are not. Moreover, variation in sexual systems did not have an influence on the correlation between geographical range and production of asexual propagules.Main conclusionsOur results challenge the long-held notion that spores, and not vegetative propagules, are involved in long-distance dispersal. Asexual reproduction seems to play a major role in shaping the global distribution patterns of liverworts, so that monoecious species do not tend to display, on average, broader distribution ranges than dioecious ones. Our results call for further investigation on the spatial genetic structure of bryophyte populations at different geographical scales depending on their mating systems to assess the dispersal capacities of spores and asexual propagules and determine their contribution in shaping species distribution ranges

U-series Disequilibria in Guatemalan Lavas, Crustal Contamination, and Implications for Magma Genesis Along the Central American Subduction Zone

New U-series results indicate that Guatemalan volcanic rocks display both 238U and 230Th excesses. 230Th excess is restricted to volcanoes in central Guatemala, both along and behind the front. 230Th excess correlates with a number of incompatible element ratios, such as Th/Nb and Ba/Th. It also shows a negative correlation with MgO. Guatemalan volcanic rocks have (230Th/232Th) ratios that overlap those of Costa Rican volcanics and are therefore considerably lower than the unusually high ratios characterizing volcanic rocks from Nicaragua. Along-arc variations in (230Th/232Th) therefore mirror those of a number of diagnostic geochemical parameters, such as Ba/La, which are symmetrical about a peak in west central Nicaragua. The one siliceous lava analyzed, from the Cerro Quemado dome complex, has a recognizable crustal imprint, distinguished, for instance, by high Th/Nb and low Ba/Th. In mafic samples, 238U excess is attributed to addition of a U-enriched fluid component from the subducting Cocos plate. Our preferred explanation for 230Th excess in Guatemalan mafic samples, on the other hand, is crustal contamination, consistent with the relatively high Th/Nb and low Ba/Th ratios in these samples. We suspect, however, that crustal contamination only exerts a sizable control over the U-series disequilibrium of mafic magmas in Guatemala, and not elsewhere along the Central American volcanic front. This agrees with previously published trace element and isotopic evidence that throughout Central America, with the exception of Guatemala, mafic magmas are largely uncontaminated by crustal material.The work was supported by NSF grant OCE-0405666