153 research outputs found
New and updated convex shape models of asteroids based on optical data from a large collaboration network
Context. Asteroid modeling efforts in the last decade resulted in a comprehensive dataset of almost 400 convex shape models and their rotation states. These efforts already provided deep insight into physical properties of main-belt asteroids or large collisional families. Going into finer detail (e.g., smaller collisional families, asteroids with sizes 20 km) requires knowledge of physical parameters of more objects. Aims. We aim to increase the number of asteroid shape models and rotation states. Such results provide important input for further studies, such as analysis of asteroid physical properties in different populations, including smaller collisional families, thermophysical modeling, and scaling shape models by disk-resolved images, or stellar occultation data. This provides bulk density estimates in combination with known masses, but also constrains theoretical collisional and evolutional models of the solar system. Methods. We use all available disk-integrated optical data (i.e., classical dense-in-time photometry obtained from public databases and through a large collaboration network as well as sparse-in-time individual measurements from a few sky surveys) as input for the convex inversion method, and derive 3D shape models of asteroids together with their rotation periods and orientations of rotation axes. The key ingredient is the support of more that 100 observers who submit their optical data to publicly available databases. Results. We present updated shape models for 36 asteroids, for which mass estimates are currently available in the literature, or for which masses will most likely be determined from their gravitational influence on smaller bodies whose orbital deflections will be observed by the ESA Gaia astrometric mission. Moreover, we also present new shape model determinations for 250 asteroids, including 13 Hungarias and three near-Earth asteroids. The shape model revisions and determinations were enabled by using additional optical data from recent apparitions for shape optimization. © 2016 ESO.J.H. greatly appreciates the CNES post-doctoral fellowship program. J.H. and M.D. were supported by the project under the contract 11-BS56-008 (SHOCKS) of the French Agence National de la Recherche (ANR), JD by grant GACR 15-04816S of the Czech Science Foundation, DO by the grant NCN 2012/S/ST9/00022 of Polish National Science Center, and A. Marciniak by grant 2014/13/D/ST9/01818 of Polish National Science Center.Peer Reviewe
An Exploration of Conformity to Medieval Male and Female Roles in the Chronicle of Alfonso X
Gender is constructed by the society in which one lives, and due to this notion, it is essential to research and analyze the implications of being male or female during specific time periods. The Middle Ages is often labeled as a patriarchal society because of the rigid roles that assigned men to the public sphere, and women to the private. Males dominated feudal society, which was defined by the three orders of society (those who pray, fight, and work). Men were expected to exude dominance in order to be considered masculine, in terms of women, war, and authority. Though we know that women intervened within these orders of society, they were undoubtedly restricted to the private sphere and left out of the hierarchy. Instead, women were confined to the roles of mother, widow, or virgin. My project focuses on the royal sphere of medieval society, exploring whether or not kings and queens were restricted to the same, stringent roles that the Middle Ages was centered around. By analyzing the Chronicle of Alfonso X, I look at how male and female identities are represented. In order to portray these historical figures as an ideal male or female the chronicler explores what signified the archetypical mold of each gender to determine whether or not Alfonso X and Queen Violante did in fact conform to the traditional norms of medieval masculinity and femininity. Most importantly, it is vital to my research to look at the bias of the narrator of the chronicle and how his status and purpose in writing Alfonso's chronicle affected how the characters are delineated
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Trends 1991: A Compendium of Data on Global Change
This document is a source of frequently used global-change data. This second issue of the Trends series expands the coverage of sites recording atmospheric concentrations of carbon dioxide (CO{sub 2}) and methane (CH{sub 4}), and it updates records reported in the first issue. New data for other trace atmospheric gases have been included in this issue; historical data on nitrous oxide (N{sub 2}) from ice cores, modern records of atmospheric concentrations of chlorofluorocarbons (CFC-11 and CFC-12) and N{sub 2}O, and estimates of global estimates of CFC-11 and CFC-12. The estimates for global and national CO{sub 2} emissions from the burning of fossil fuels, the production of cement, and gas flaring have been revised and updated. Regional CO{sub 2} emission estimates have been added, and long-term temperature records have been updated and expanded. Data records are presented in four- to six-page formats, each dealing with a specific site, region, or emissions species. The data records include tables and graphs; discussion of methods for collecting, measuring, and reporting the data; trends in the data; and references to literature that provides further information. All data appearing in the document are available on digital media from the Carbon Dioxide Information Analysis Center
Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution
The larger number of models of asteroid shapes and their rotational states
derived by the lightcurve inversion give us better insight into both the nature
of individual objects and the whole asteroid population. With a larger
statistical sample we can study the physical properties of asteroid
populations, such as main-belt asteroids or individual asteroid families, in
more detail. Shape models can also be used in combination with other types of
observational data (IR, adaptive optics images, stellar occultations), e.g., to
determine sizes and thermal properties. We use all available photometric data
of asteroids to derive their physical models by the lightcurve inversion method
and compare the observed pole latitude distributions of all asteroids with
known convex shape models with the simulated pole latitude distributions. We
used classical dense photometric lightcurves from several sources and
sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff,
Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the
lightcurve inversion method to determine asteroid convex models and their
rotational states. We also extended a simple dynamical model for the spin
evolution of asteroids used in our previous paper. We present 119 new asteroid
models derived from combined dense and sparse-in-time photometry. We discuss
the reliability of asteroid shape models derived only from Catalina Sky Survey
data (IAU code 703) and present 20 such models. By using different values for a
scaling parameter cYORP (corresponds to the magnitude of the YORP momentum) in
the dynamical model for the spin evolution and by comparing synthetics and
observed pole-latitude distributions, we were able to constrain the typical
values of the cYORP parameter as between 0.05 and 0.6.Comment: Accepted for publication in A&A, January 15, 201
Resveratrol, by Modulating RNA Processing Factor Levels, Can Influence the Alternative Splicing of Pre-mRNAs
Alternative pre-mRNA splicing defects can contribute to, or result from, various diseases, including cancer. Aberrant mRNAs, splicing factors and other RNA processing factors have therefore become targets for new therapeutic interventions. Here we report that the natural polyphenol resveratrol can modulate alternative splicing in a target-specific manner. We transfected minigenes of several alternatively spliceable primary mRNAs into HEK293 cells in the presence or absence of 1, 5, 20 and 50 µM resveratrol and measured exon levels by semi-quantitative PCR after separation by agarose gel electrophoresis. We found that 20 µg/ml and 50 µg/ml of resveratrol affected exon inclusion of SRp20 and SMN2 pre-mRNAs, but not CD44v5 or tau pre-mRNAs. By Western blotting and immunofluorescence we showed that this effect may be due to the ability of resveratrol to change the protein level but not the localization of several RNA processing factors. The processing factors that increased significantly were ASF/SF2, hnRNPA1 and HuR, but resveratrol did not change the levels of RBM4, PTBP1 and U2AF35. By means of siRNA-mediated knockdown we depleted cells of SIRT1, regarded as a major target of resveratrol, and showed that the effect on splicing was not dependent on SIRT1. Our results suggest that resveratrol might be an attractive small molecule to treat diseases in which aberrant splicing has been implicated, and justify more extensive research on the effects of resveratrol on the splicing machinery
New Protocetid Whale from the Middle Eocene of Pakistan: Birth on Land, Precocial Development, and Sexual Dimorphism
BACKGROUND: Protocetidae are middle Eocene (49-37 Ma) archaeocete predators ancestral to later whales. They are found in marine sedimentary rocks, but retain four legs and were not yet fully aquatic. Protocetids have been interpreted as amphibious, feeding in the sea but returning to land to rest. METHODOLOGY/PRINCIPAL FINDINGS: Two adult skeletons of a new 2.6 meter long protocetid, Maiacetus inuus, are described from the early middle Eocene Habib Rahi Formation of Pakistan. M. inuus differs from contemporary archaic whales in having a fused mandibular symphysis, distinctive astragalus bones in the ankle, and a less hind-limb dominated postcranial skeleton. One adult skeleton is female and bears the skull and partial skeleton of a single large near-term fetus. The fetal skeleton is positioned for head-first delivery, which typifies land mammals but not extant whales, evidence that birth took place on land. The fetal skeleton has permanent first molars well mineralized, which indicates precocial development at birth. Precocial development, with attendant size and mobility, were as critical for survival of a neonate at the land-sea interface in the Eocene as they are today. The second adult skeleton is the most complete known for a protocetid. The vertebral column, preserved in articulation, has 7 cervicals, 13 thoracics, 6 lumbars, 4 sacrals, and 21 caudals. All four limbs are preserved with hands and feet. This adult is 12% larger in linear dimensions than the female skeleton, on average, has canine teeth that are 20% larger, and is interpreted as male. Moderate sexual dimorphism indicates limited male-male competition during breeding, which in turn suggests little aggregation of food or shelter in the environment inhabited by protocetids. CONCLUSIONS/SIGNIFICANCE: Discovery of a near-term fetus positioned for head-first delivery provides important evidence that early protocetid whales gave birth on land. This is consistent with skeletal morphology enabling Maiacetus to support its weight on land and corroborates previous ideas that protocetids were amphibious. Specimens this complete are virtual 'Rosetta stones' providing insight into functional capabilities and life history of extinct animals that cannot be gained any other way
Myelin Proteomics: Molecular Anatomy of an Insulating Sheath
Fast-transmitting vertebrate axons are electrically insulated with multiple layers of nonconductive plasma membrane of glial cell origin, termed myelin. The myelin membrane is dominated by lipids, and its protein composition has historically been viewed to be of very low complexity. In this review, we discuss an updated reference compendium of 342 proteins associated with central nervous system myelin that represents a valuable resource for analyzing myelin biogenesis and white matter homeostasis. Cataloging the myelin proteome has been made possible by technical advances in the separation and mass spectrometric detection of proteins, also referred to as proteomics. This led to the identification of a large number of novel myelin-associated proteins, many of which represent low abundant components involved in catalytic activities, the cytoskeleton, vesicular trafficking, or cell adhesion. By mass spectrometry-based quantification, proteolipid protein and myelin basic protein constitute 17% and 8% of total myelin protein, respectively, suggesting that their abundance was previously overestimated. As the biochemical profile of myelin-associated proteins is highly reproducible, differential proteome analyses can be applied to material isolated from patients or animal models of myelin-related diseases such as multiple sclerosis and leukodystrophies
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Trends '91: A compendium of data on global change---highlights
The Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge National Laboratory (ORNL) has been prompted to produce the series Trends, a concise inventory of data in response to heightened concern about global environmental issues, in particular climate changes induced by the greenhouse effect. This report contains extracts from Trends '91 to illustrate the content, style, and presentation of data contained in the full 700-page report. This report includes a listing of the investigators contributing data for Trends '91. In addition, it contains the abstract, foreword, and acknowledgments, as well as the introduction and a sample data record from each of the reports's five chapters. The chapters are Atmospheric CO[sub 2],'' Atmospheric CH[sub 4],'' Other Trace Gases,'' CO[sub 2] Emissions,'' and Temperature.'' Appendix A provides information about CDIAC and its activities related to global environmental issues. Appendix B lists the contents of the full report. An order form for obtaining a free copy of Trends '91 is found in Appendix C
An Exploration of Conformity to Medieval Male and Female Roles in the Chronicle of Alfonso X
Gender is constructed by the society in which one lives and due to this notion it is essential to research and analyze the implications of being male or female during specific time periods. The Middle Ages is often labeled as a patriarchal society because of the rigid roles that assigned men to the public sphere and women to the private. Males dominated feudal society which was defined by the three orders of society (those who pray fight and work). Men were expected to exude dominance in order to be considered masculine in terms of women war and authority. Though we know that women intervened within these orders of society they were undoubtedly restricted to the private sphere and left out of the hierarchy. Instead women were confined to the roles of mother widow or virgin. My project focuses on the royal sphere of medieval society exploring whether or not kings and queens were restricted to the same stringent roles that the Middle Ages was centered around. By analyzing the Chronicle of Alfonso X I look at how male and female identities are represented. In order to portray these historical figures as an ideal male or female the chronicler explores what signified the archetypical mold of each gender to determine whether or not Alfonso X and Queen Violante did in fact conform to the traditional norms of medieval masculinity and femininity. Most importantly it is vital to my research to look at the bias of the narrator of the chronicle and how his status and purpose in writing Alfonso's chronicle affected how the characters are delineated
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