3,004 research outputs found
On the Mass Function, Multiplicity, and Origins of Wide-Orbit Giant Planets
A major outstanding question regarding the formation of planetary systems is
whether wide-orbit giant planets form differently than close-in giant planets.
We aim to establish constraints on two key parameters that are relevant for
understanding the formation of wide-orbit planets: 1) the relative mass
function and 2) the fraction of systems hosting multiple companions. In this
study, we focus on systems with directly imaged substellar companions, and the
detection limits on lower-mass bodies within these systems. First, we uniformly
derive the mass probability distributions of known companions. We then combine
the information contained within the detections and detection limits into a
survival analysis statistical framework to estimate the underlying mass
function of the parent distribution. Finally, we calculate the probability that
each system may host multiple substellar companions. We find that 1) the
companion mass distribution is rising steeply toward smaller masses, with a
functional form of , and consequently, 2) many of
these systems likely host additional undetected sub-stellar companions.
Combined, these results strongly support the notion that wide-orbit giant
planets are formed predominantly via core accretion, similar to the better
studied close-in giant planets. Finally, given the steep rise in the relative
mass function with decreasing mass, these results suggest that future deep
observations should unveil a greater number of directly imaged planets.Comment: 19 pages, 10 figures, accepted to Ap
Bowling online : the Internet and the new social capital.
The decline thesis proponents in the social capital literature have largely ignored the fastest growing venue for new social capital formation – the Internet. We argue that the Internet is making a larger impact than the current research acknowledges. Using survey data from the Pew Internet & American Life Project combined with a survey of college students, we confirm a strong positive relationship between online social networking and political participation. Further, we present evidence that, at least in 2008 election, there was a bias toward voting for Democrats among those who utilized online social networking services including Facebook and Twitter. The implications of these results are discussed
The electronic ballot box : class, age and racial bias on the Internet.
This research creates a theoretical framework for understanding the effect of Internet voting on the electorate. Based on standard Downsian rational choice voting theory, we claim that Internet voting lowers the cost of voting for certain voting demographics based upon race, age, and income.We further contend that this electoral advantage may crystallize the growing turnout disparity be-tween demographic groups. The theory is tested using Bayesian inferential methods with data from the Internet turnout in the 2000 Arizona Democratic Presidential Primary merged with demographic data obtained from the 2000 Census. Our findings lend support for the theory that the Internet provides an electoral bias towards white voters, younger voters, and to the more affluent
Entanglement Entropy Near Kondo-Destruction Quantum Critical Points
We study the impurity entanglement entropy in quantum impurity models
that feature a Kondo-destruction quantum critical point (QCP) arising from a
pseudogap in the conduction-band density of states or from coupling to a
bosonic bath. On the local-moment (Kondo-destroyed) side of the QCP, the
entanglement entropy contains a critical component that can be related to the
order parameter characterizing the quantum phase transition. In Kondo models
describing a spin-\Simp, assumes its maximal value of \ln(2\Simp+1)
at the QCP and throughout the Kondo phase, independent of features such as
particle-hole symmetry and under- or over-screening. In Anderson models,
is nonuniversal at the QCP, and at particle-hole symmetry, rises monotonically
on passage from the local-moment phase to the Kondo phase; breaking this
symmetry can lead to a cusp peak in due to a divergent charge
susceptibility at the QCP. Implications of these results for quantum critical
systems and quantum dots are discussed.Comment: 15 pages, 8 figures, replaced with published version, Editor's
Suggestio
Stand Your Ground in Florida: The Effect of Race, Location and Weapons on Convictions
The implications of laws allowing citizens to respond with deadly force when they believe they are threatened is the subject of significant conjecture in the media and scholarship. The adoption of “Stand Your Ground” laws has increased across the nation despite little data or findings that attempt to capture the ramifications of enacting this policy. This research explores the effect of the “Stand Your Ground” legal defense on criminal convictions in Florida. After exploring the historic assumptions and motivations behind the adoption and use of the Stand Your Ground law in Florida, we use data gathered from local newspapers, the Florida Department of Law Enforcement and the national census to assess the impact of the new law on self-defense convictions in Florida. We test some of the claims made by the media and political pundits regarding how the law is used and how effective a defense it has been in Florida. Our data has over 200 “Stand Your Ground” cases in 28 counties in Florida. Our analysis shows two significant factors weighing on the success or failure of the use of the law to defend a charge in a criminal case. Initially, we find that race is a significant predictor of success. When the victim is a minority, the perpetrator is less likely to be convicted when using the “Stand Your Ground” defense in Florida. White victims lead to a higher likelihood of conviction. At the county level, the importance of race is evident as well. In counties with higher minority populations, there is a higher probability of conviction under the “Stand Your Ground” defense. Secondarily, we found a significant predictor relating to the use of firearms. A perpetrator is less likely to be convicted when using a gun rather than a knife or other weapon. Shoot, but don’t stab! In Florida, if you stand your ground, then who you are, where you are, and how you defend yourself are important factors. The implications of these findings are discussed
Acid-Labile Traceless Click Linker for Protein Transduction
Intracellular delivery of active proteins presents an interesting approach in research and therapy. We created a protein transduction shuttle based on a new traceless click linker that combines the advantages of click reactions with implementation of reversible pH-sensitive bonds. The azidomethyl-methylmaleic anhydride (AzMMMan) linker was found compatible with different click chemistries, demonstrated in bioreversible protein modification with dyes, polyethylene glycol, or a transduction carrier. Linkages were stable at physiological pH but reversible at the mild acidic pH of endosomes or lysosomes. We show that pH-reversible attachment of a defined endosome-destabilizing three-arm oligo(ethane amino)amide carrier generates an effective shuttle for protein delivery. The cargo protein nlsEGFP, when coupled via the traceless AzMMMan linker, experiences efficient cellular uptake and endosomal escape into the cytosol, followed by import into the nucleus. In contrast, irreversible linkage to the same shuttle hampers nuclear delivery of nlsEGFP which after uptake remains trapped in the cytosol. Successful intracellular delivery of bioactive ß-galactosidase as a model enzyme was also demonstrated using the pH-controlled shuttle system
The Orbit of the Companion to HD 100453A: Binary-Driven Spiral Arms in a Protoplanetary Disk
HD 100453AB is a 10+/-2 Myr old binary whose protoplanetary disk was recently
revealed to host a global two-armed spiral structure. Given the relatively
small projected separation of the binary (1.05", or ~108 au), gravitational
perturbations by the binary seemed to be a likely driving force behind the
formation of the spiral arms. However, the orbit of these stars remained poorly
understood, which prevented a proper treatment of the dynamical influence of
the companion on the disk. We observed HD 100453AB between 2015-2017 utilizing
extreme adaptive optics systems on the Very Large Telescope and Magellan Clay
Telescope. We combined the astrometry from these observations with published
data to constrain the parameters of the binary's orbit to a=1.06"+/-0.09",
e=0.17+/-0.07, and i=32.5+/- 6.5 degrees. We utilized publicly available ALMA
CO data to constrain the inclination of the disk to i~28 degrees, which is
relatively co-planar with the orbit of the companion and consistent with
previous estimates from scattered light images. Finally, we input these
constraints into hydrodynamical and radiative transfer simulations to model the
structural evolution of the disk. We find that the spiral structure and
truncation of the circumprimary disk in HD 100453 are consistent with a
companion-dirven origin. Furthermore, we find that the primary star's rotation,
its outer disk, and the companion exhibit roughly the same direction of angular
momentum, and thus the system likely formed from the same parent body of
material.Comment: 28 pages, 11 figures, Accepted to Ap
Beyond Survey Self-Reports: Using Physiology to Tap Political Orientations
Some aspects of our attitudes are composed of things outside of our consciousness. However, traditional survey research does not use measurements that are able to tap into these aspects of public opinion. We describe, recommend, and demonstrate a procedure by which non-self-reported responses can be measured in order to test whether these responses have independent effects on individuals’ preferences. We use one of the better-known physiological measures—electrodermal activity or skin conductance—and illustrate its potential by reporting our own study of attitudes toward President Barack Obama. We find that both self-reported emotional responses and physiological responses to Obama’s image independently correlate with variation in the intensity of attitudes regarding his job approval and his central policy proposal: health-care reform
Transcriptome analysis of Taenia solium cysticerci using Open reading Frame ESTS (ORESTES)
<p>Abstract</p> <p>Background</p> <p>Human infection by the pork tapeworm <it>Taenia solium </it>affects more than 50 million people worldwide, particularly in underdeveloped and developing countries. Cysticercosis which arises from larval encystation can be life threatening and difficult to treat. Here, we investigate for the first time the transcriptome of the clinically relevant cysticerci larval form.</p> <p>Results</p> <p>Using Expressed Sequence Tags (ESTs) produced by the ORESTES method, a total of 1,520 high quality ESTs were generated from 20 ORESTES cDNA mini-libraries and its analysis revealed fragments of genes with promising applications including 51 ESTs matching antigens previously described in other species, as well as 113 sequences representing proteins with potential extracellular localization, with obvious applications for immune-diagnosis or vaccine development.</p> <p>Conclusion</p> <p>The set of sequences described here will contribute to deciphering the expression profile of this important parasite and will be informative for the genome assembly and annotation, as well as for studies of intra- and inter-specific sequence variability. Genes of interest for developing new diagnostic and therapeutic tools are described and discussed.</p
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