Differential Rotation and Magnetism in Simulations of Fully Convective Stars

Stars of sufficiently low mass are convective throughout their interiors, and so do not possess an internal boundary layer akin to the solar tachocline. Because that interface figures so prominently in many theories of the solar magnetic dynamo, a widespread expectation had been that fully convective stars would exhibit surface magnetic behavior very different from that realized in more massive stars. Here I describe how recent observations and theoretical models of dynamo action in low-mass stars are partly confirming, and partly confounding, this basic expectation. In particular, I present the results of 3--D MHD simulations of dynamo action by convection in rotating spherical shells that approximate the interiors of 0.3 solar-mass stars at a range of rotation rates. The simulated stars can establish latitudinal differential rotation at their surfaces which is solar-like at ``rapid'' rotation rates (defined within) and anti-solar at slower rotation rates; the differential rotation is greatly reduced by feedback from strong dynamo-generated magnetic fields in some parameter regimes. I argue that this ``flip'' in the sense of differential rotation may be observable in the near future. I also briefly describe how the strength and morphology of the magnetic fields varies with the rotation rate of the simulated star, and show that the maximum magnetic energies attained are compatible with simple scaling arguments.Comment: 9 pages, 2 color figures, to appear in Proc. IAU Symposium 271, "Astrophysical Dynamics: from Stars to Galaxies

Analysis of Automobile Advertisements in American Magazines

The automobile is one of the most important products in American consumer culture. Throughout the history of the automobile industry in America, advertising has been an important strategy for marketing automobiles and their features to consumers on a mass scale. The purpose of this study was to evaluate how print (magazine) automobile advertisements have changed through time (1960-2013) and across different genres of magazines: general (National Geographic, New Yorker), male-oriented (Esquire), female-oriented (Cosmopolitan), and ethnic (Ebony). The trends that we examined included: numbers and proportions of car advertisements, relative numbers of domestic and foreign car advertisements, and the mix of automobile features. We found that the total number of car advertisements per magazine peaked in the late 1990s overall, with differences among the magazine genres. The number of advertisements for cars produced by American manufacturers peaked in the mid-1990s. The number of foreign car advertisements significantly increased after 1975, with Japanese cars leading this group. We discuss the trends in advertising parameters over time and across magazine genres in light of changes in buyer attitudes, including attitudes towards the environment

Bridging the Conceptual Gap Between Law and Morality: A Critical Response to H.L.A. Hart’s The Concept Of Law

In The Concept of Law, H.L.A. Hart develops his theory for a concept of law that rejects the possibility of a necessary connection between law and morality i.e., what the law is from what the law ought to be. He admittedly does so for moral reasons. If there is a conceptual gap between law and morality, it is possible to use the latter as a critical standard for assessing the law by questioning 'is this law too iniquitous to obey or apply?' However, this concept of law is flawed. If the human capacity for moral reason can be used to correctly identify and disobey legally valid though morally deplorable laws, one must assume that belief in what the law ought to be is an inherently moral aspect of the internal point of view. Furthermore, unless one chooses to acknowledge the suppositions of command theory-that is, that law is nothing more than habitual congruencies or the command of a supreme sovereignone must assume Hart's idea of the ultimate rule of recognition as an external statement of fact relating to societies internal perspective of what ought to be. In this way, the inclusion of the internal perspective as a necessary aspect of law entails a connection between law and morality. Otherwise, what law is and what law ought to be become synonymous under a merely external viewpoint. This does not reflect the reality of how individuals assess the law or their actions in relation to the law

From solar-like to anti-solar differential rotation in cool stars

Stellar differential rotation can be separated into two main regimes: solar-like when the equator rotates faster than the poles and anti-solar when the polar regions rotate faster than the equator. We investigate the transition between these two regimes with 3-D numerical simulations of rotating spherical shells. We conduct a systematic parameter study which also includes models from different research groups. We find that the direction of the differential rotation is governed by the contribution of the Coriolis force in the force balance, independently of the model setup (presence of a magnetic field, thickness of the convective layer, density stratification). Rapidly-rotating cases with a small Rossby number yield solar-like differential rotation, while weakly-rotating models sustain anti-solar differential rotation. Close to the transition, the two kinds of differential rotation are two possible bistable states. This study provides theoretical support for the existence of anti-solar differential rotation in cool stars with large Rossby numbers.Comment: 5 pages, 6 figures, accepted for publication in MNRA

Feasibility of MV CBCT-based treatment planning for urgent radiation therapy: dosimetric accuracy of MV CBCT-based dose calculations.

Unlike scheduled radiotherapy treatments, treatment planning time and resources are limited for emergency treatments. Consequently, plans are often simple 2D image-based treatments that lag behind technical capabilities available for nonurgent radiotherapy. We have developed a novel integrated urgent workflow that uses onboard MV CBCT imaging for patient simulation to improve planning accuracy and reduce the total time for urgent treatments. This study evaluates both MV CBCT dose planning accuracy and novel urgent workflow feasibility for a variety of anatomic sites. We sought to limit local mean dose differences to less than 5% compared to conventional CT simulation. To improve dose calculation accuracy, we created separate Hounsfield unit-to-density calibration curves for regular and extended field-of-view (FOV) MV CBCTs. We evaluated dose calculation accuracy on phantoms and four clinical anatomical sites (brain, thorax/spine, pelvis, and extremities). Plans were created for each case and dose was calculated on both the CT and MV CBCT. All steps (simulation, planning, setup verification, QA, and dose delivery) were performed in one 30 min session using phantoms. The monitor units (MU) for each plan were compared and dose distribution agreement was evaluated using mean dose difference over the entire volume and gamma index on the central 2D axial plane. All whole-brain dose distributions gave gamma passing rates higher than 95% for 2%/2 mm criteria, and pelvic sites ranged between 90% and 98% for 3%/3 mm criteria. However, thoracic spine treatments produced gamma passing rates as low as 47% for 3%/3 mm criteria. Our novel MV CBCT-based dose planning and delivery approach was feasible and time-efficient for the majority of cases. Limited MV CBCT FOV precluded workflow use for pelvic sites of larger patients and resulted in image clearance issues when tumor position was far off midline. The agreement of calculated MU on CT and MV CBCT was acceptable for all treatment sites

Life cycle studies of the hexose transporter of Plasmodium species and genetic validation of their essentiality

A Plasmodium falciparum hexose transporter (PfHT) has previously been shown to be a facilitative glucose and fructose transporter. Its expression in Xenopus laevis oocytes and the use of a glucose analogue inhibitor permitted chemical validation of PfHT as a novel drug target. Following recent re-annotations of the P. falciparum genome, other putative sugar transporters have been identified. To investigate further if PfHT is the key supplier of hexose to P. falciparum and to extend studies to different stages of Plasmodium spp., we functionally analysed the hexose transporters of both the human parasite P. falciparum and the rodent parasite Plasmodium berghei using gene targeting strategies. We show here the essential function of pfht for the erythrocytic parasite growth as it was not possible to knockout pfht unless the gene was complemented by an episomal construct. Also, we show that parasites are rescued from the toxic effect of a glucose analogue inhibitor when pfht is overexpressed in these transfectants. We found that the rodent malaria parasite orthologue, P. berghei hexose transporter (PbHT) gene, was similarly refractory to knockout attempts. However, using a single cross-over transfection strategy, we generated transgenic P. berghei parasites expressing a PbHT–GFP fusion protein suggesting that locus is amenable for gene targeting. Analysis of pbht-gfp transgenic parasites showed that PbHT is constitutively expressed through all the stages in the mosquito host in addition to asexual stages. These results provide genetic support for prioritizing PfHT as a target for novel antimalarials that can inhibit glucose uptake and kill parasites, as well as unveiling the expression of this hexose transporter in mosquito stages of the parasite, where it is also likely to be critical for survival

What is a Virus?

About our Book Hi everyone! Hannah here. As college students, my friend Emily and I are studying from home. We realized you probably are working from home too, and might not quite know why. So we put together this book to try and explain viruses- the annoying buggers behind the coronavirus and even the common cold. We hope you enjoy it and learn some new things about science too! Copyright © 2020 Hannah Margolis This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License. Permission is granted to distribute this publication in its entirety, without change and without charge.Otherwise, however, all rights reserved and no part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law.ISBN: 978-1-7923-4213-