Li I and K I Scatter in Cool Pleiades Dwarfs

We utilize high-resolution (R~60,000), high S/N (~100) spectroscopy of 17 cool Pleiades dwarfs to examine the confounding star-to-star scatter in the 6707 Li I line strengths in this young cluster. Our Pleiads, selected for their small projected rotational velocity and modest chromospheric emission, evince substantial scatter in the linestrengths of 6707 Li I feature that is absent in the 7699 K I resonance line. The Li I scatter is not correlated with that in the high-excitation 7774 O I feature, and the magnitude of the former is greater than the latter despite the larger temperature sensitivity of the O I feature. These results suggest that systematic errors in linestrength measurements due to blending, color (or color-based T_eff) errors, or line formation effects related to an overlying chromosphere are not the principal source of Li I scatter in our stars. There do exist analytic spot models that can produce the observed Li scatter without introducing scatter in the K I line strengths or the color-magnitude diagram. However, these models predict factor of >3 differences in abundances derived from the subordinate 6104 and resonance 6707 Li I features; we find no difference in the abundances determined from these two features. These analytic spot models also predict CN line strengths significantly larger than we observe in our spectra. The simplest explanation of the Li, K, CN, and photometric data is that there must be a real abundance component to the Pleiades Li dispersion. We suggest that this real abundance component is the manifestation of relic differences in erstwhile pre-main-sequence Li burning caused by effects of surface activity on stellar structure. We discuss observational predictions of these effects.Comment: 35 pages, 7 figures; accepted by Ap

Experimental study of flow deflectors designed to alleviate ground winds induced by exhaust of 80-by 120-foot wind tunnel

An experimental study directed at finding a deflector ramp that will reduce to an acceptable level the ground winds under the exhaust jet of the 80 by 120 Foot Wind Tunnel at NASA Ames Center is described. A one-fifieth scale model of the full-scale facility was used to investigate how the jet flow field was modified by the various design parameters of the ramp. It was concluded that the ground winds were alleviated sufficiently by a ramp with end plates located next to the wind tunnel building along the ground edge of the exhaust opening. At full scale, the ramp should have a slant length of 7.62 m (25 ft) or more, and would be elevated at about 45 degrees to the ground plane. The material should have holes less than 15.2 (6 in) in diameter distributed uniformly over its surface to produce a porosity of about 30%

Human papillomavirus vaccine and behavioural disinhibition

Objectives—We sought to identify characteristics of parents who believe in sexual disinhibition and that Pap smears can safely be stopped after females receive HPV vaccine. Methods—We surveyed 647 parents of adolescent girls living in areas of North Carolina with elevated rates of cervical cancer. We report data primarily from a survey conducted in Fall 2008. Results—Only 16% (101/647) of parents agreed that teenage girls who receive HPV vaccine may be more likely to have sex. Parents who believed in vaccine-induced sexual disinhibition were more likely to be older (OR 1.89; 95% CI 1.09, 3.26) or report conservative political views (OR 2.26; 95% CI 1.37, 3.73). Parents were less likely to believe in sexual disinhibition if they had greater knowledge about HPV vaccine (OR 0.52; 95% CI 0.32 0.85) or if their daughters had received HPV vaccine (OR 0.31; 95% CI 0.17, 0.57). While few parents (5%, 30/647) believed that women could safely stop getting regular Pap smears after receiving HPV vaccine, this belief was somewhat more common among racial and ethnic minority parents (16%) and among fathers (13%). Conclusions—Few parents believed that HPV vaccine is likely to lead to increased sexual activity among females or reduce the need for vaccinated women to have regular Pap smears in the future. Characterizing parents who hold beliefs in behavioral disinhibition is important as clinicians encountering parents in practice may desire information about this population

Predicting lung cancer recurrence from circulating tumour DNA. Commentary on 'Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution'

No abstract available

A Neural Circuit Arbitrates between Persistence and Withdrawal in Hungry Drosophila

In pursuit of food, hungry animals mobilize significant energy resources and overcome exhaustion and fear. How need and motivation control the decision to continue or change behavior is not understood. Using a single fly treadmill, we show that hungry flies persistently track a food odor and increase their effort over repeated trials in the absence of reward suggesting that need dominates negative experience. We further show that odor tracking is regulated by two mushroom body output neurons (MBONs) connecting the MB to the lateral horn. These MBONs, together with dopaminergic neurons and Dop1R2 signaling, control behavioral persistence. Conversely, an octopaminergic neuron, VPM4, which directly innervates one of the MBONs, acts as a brake on odor tracking by connecting feeding and olfaction. Together, our data suggest a function for the MB in internal state-dependent expression of behavior that can be suppressed by external inputs conveying a competing behavioral drive

Soft Contributions to Hard Pion Photoproduction

Hard, or high transverse momentum, pion photoproduction can be a tool for probing the parton structure of the beam and target. We estimate the soft contributions to this process, with an eye toward delineating the region where perturbatively calculable processes dominate. Our soft process estimate is based on vector meson dominance and data based parameterizations of semiexclusive hadronic cross sections. We find that soft processes dominate in single pion photoproduction somewhat past 2 GeV transverse momentum at a few times 10 GeV incoming energy. The recent polarization asymmetry data is consistent with the perturbative asymmetry being diluted by polarization insensitive soft processes. Determining the polarized gluon distribution using hard pion photoproduction appears feasible with a few hundred GeV incoming energy (in the target rest frame).Comment: 6 pages, 5 figure

Innovative Conservation Agriculture Approaches: Food Security and Climate Action through Soil and Water Conservation (INCAA)

The crucial challenge for smallholder farmers in sub-Saharan Africa is feeding a growing population while preserving the natural resource base of the agricultural system. In future, this challenge will be exacerbated by soil degradation and climate change. Conservation Agriculture (CA) has been promoted as a strategy that can improve yields, soils and effective water use. CA thus has potential to increase the resilience of farming systems facing the mentioned challenges. However, CA since its introduction in sub-Sahara Africa has not moved from the invention to the innovation stage: the CA innovation seen as a package is not meeting the farmers’ needs, capabilities and opportunities. Overall, the attempt to transfer this innovation in a conventional linear way from science to farm has been disappointing. The INCAA project is designed as an action research process aimed at targeting the challenging (and often missing) interfaces of science-driven technology and local realities in innovation systems. The overall objective of INCAA is to mentor and analyse a learning process that supports the innovation of CA in sub-Saharan Africa. The case studies of the project are Laikipia County, Kenya and Koumbia District, Burkina Faso. Building on the experiences of past projects, INCAA will (1) map benefits and adaptations of CA in innovation systems around the partner projects; (2) foster joined learning of stakeholders to test and validate CA tools; and (3) develop learning strategies for an innovation process towards CA including institutional and individual dimensions. This project will start from those who take the final decision on the fate of CA - the farmers. By assessing how farmers have actually adapted and implemented CA, we can derive lessons on the benefits and losses related to such CA modes for all stakeholders involved in the agricultural system. This contribution will 1) introduce the overall conceptual, methodological and structural design of the project and 2) highlight its first preliminary results which so far show high influence of gender aspects towards the adoption decision process. Differing roles of and expectations towards men and women within the farming communities are often an invisible obstacle for further adoption of CA

Electrodynamic Tether

A tether system for providing thrust to or power subsystems of an artificial satellite in a low earth orbit. The tether has three main sections, an insulated section connected to the satellite, a conducting section connected to the insulating section for drawing in and releasing electrons from the space plasma and a non-conducting section for providing a tension to the other sections of the tether. An oxygen resistant coating is applied to the bare wire of the conducting section as well as the insulated wires of the insulated section that prevents breakdown during tether operations in the space plasma. The insulated and bare wire sections also surround a high tensile flexible polymer core to prevent any debris from breaking the tether during use