Impact basins in Southern Daedalia, Mars: Evidence for clustered impactors?

The distribution of ancient massifs and old cratered terrain in the southern Daedalia region indicate the presence of at least two and probably three impact basins of large size. One of these is located near where Craddock et al. placed their center for the Daedalia Basin, but it has very different ring diameters. These basins have rings exceeding 1000 km diameter and overlap significantly with centers separated by 500 to 600 km at nearly identical latitudes of -26 to -29 deg. The smaller westernmost basin appears slightly better preserved, but there is little evidence for obvious superposition that might imply a temporal sequence. Recognizing the improbability of random impacts producing aligned, nearly contemporaneous features, we suggest these basins may have resulted from clustered impactors

Genes, Economics, and Happiness

We explore the influence of genetic variation on subjective well-being by employing a twin design and genetic association study. In a nationally-representative twin sample, we first show that about 33% of the variation in life satisfaction is explained by genetic variation. Although previous studies have shown that baseline happiness is significantly heritable, little research has considered molecular genetic associations with subjective well-being. We study the relationship between a functional polymorphism on the serotonin transporter gene (5-HTTLPR) and life satisfaction. We initially find that individuals with the longer, transcriptionally more efficient variant of this genotype report greater life satisfaction (n=2,545, p=0.012). However, our replication attempts on independent samples produce mixed results indicating that more work needs to be done to better understand the relationship between this genotype and subjective well-being. This work has implications for how economists think about the determinants of utility, and the extent to which exogenous shocks might affect individual well-being.life satisfaction, twin study, genetic association, serotonin transporter gene, 5-HTTLPR, rs2020933

Genes, Economics and Happiness

A major finding from research into the sources of subjective well-being is that individuals exhibit a "baseline" level of happiness. We explore the influence of genetic variation by employing a twin design and genetic association study. We first show that about 33% of the variation in happiness is explained by genes. Next, using two independent data sources, we present evidence that individuals with a transcriptionally more efficient version of the serotonin transporter gene (SLC6A4) report significantly higher levels of life satisfaction. These results are the first to identify a specific gene that is associated with happiness and suggest that behavioral models benefit from integrating genetic variation.wellbeing, socio-demographics, happiness, genetics, life satisfaction

Characterization of the Rubella Virus Nonstructural Protease Domain and Its Cleavage Site

The region of the rubella virus nonstructural open reading frame that contains the papain-like cysteine protease domain and its cleavage site was expressed with a Sindbis virus vector. Cys-1151 has previously been shown to be required for the activity of the protease (L. D. Marr, C.-Y. Wang, and T. K. Frey, Virology 198:586–592, 1994). Here we show that His-1272 is also necessary for protease activity, consistent with the active site of the enzyme being composed of a catalytic dyad consisting of Cys-1151 and His-1272. By means of radiochemical amino acid sequencing, the site in the polyprotein cleaved by the nonstructural protease was found to follow Gly-1300 in the sequence Gly-1299–Gly-1300–Gly-1301. Mutagenesis studies demonstrated that change of Gly-1300 to alanine or valine abrogated cleavage. In contrast, Gly-1299 and Gly-1301 could be changed to alanine with retention of cleavage, but a change to valine abrogated cleavage. Coexpression of a construct that contains a cleavage site mutation (to serve as a protease) together with a construct that contains a protease mutation (to serve as a substrate) failed to reveal trans cleavage. Coexpression of wild-type constructs with protease-mutant constructs also failed to reveal trans cleavage, even after extended in vitro incubation following lysis. These results indicate that the protease functions only in cis, at least under the conditions tested

Effects due to overlapping large impact basins on Mars

Many ancient, highly degraded large impact basins exist on Mars. In many cases these basins overlap or are overlapped by more easily observed, presumably younger, impact basins. While impact basin overlap is becoming more recognized, the effects of such overlap have only occassionally been described. Such effects will depend on a variety of factors including the absolute and relative size of the basins, the degree of overlap, the state of the lithosphere and its thermal gradient at the time of impact, and the time between impacts. There now exists enough evidence for overlapping basins of different sizes that some of these can be discussed. This paper highlights some examples of the obvious effects of basin overlap

Exciting dark matter in the galactic center

We reconsider the proposal of excited dark matter (DM) as an explanation for excess 511 keV gamma rays from positrons in the galactic center. We quantitatively compute the cross section for DM annihilation to nearby excited states, mediated by exchange of a new light gauge boson with off-diagonal couplings to the DM states. In models where both excited states must be heavy enough to decay into e^+ e^- and the ground state, the predicted rate of positron production is never large enough to agree with observations, unless one makes extreme assumptions about the local circular velocity in the Milky Way, or alternatively if there exists a metastable population of DM states which can be excited through a mass gap of less than 650 keV, before decaying into electrons and positrons.Comment: Dedicated to the memory of Lev Kofman; 16 pages, 9 figures; v3 added refs, minor changes, accepted to PR

Immigration and internal migration “flight”: A California case study

Recent analyses of 1990 census migration data have pointed up disparities in the way immigration and internal migration contributions affect an area's demographic profile. They show that there is little overlap between states with large population gains from internal migration from other parts of the United States and states with large population gains from immigration from abroad. This emerging pattern, along with the fact that immigration and internal migration select on very different demographic characteristics, could lead toward a “demographic balkanization” of the nation's population. This paper evaluates immigration-induced out-movement from California, based on an analysis of recently released migration data from the 1990 U.S. census. The results presented here suggest that California's out-migration consists of two different migration systems: first, an immigration-induced “flight” that exports lower income and less-educated Californians, primarily, to the nearby states of Washington, Oregon, Nevada and Arizona. And second, a more conventional migration exchange with the rest of the United States that involves the redistribution of better educated, higher income migrants. It is the former migration system which appears to be most responsive to the low-skilled immigration flows, while the latter should be responsive to more conventional labor market employment characteristics. This implies that, irrespective of changing economic conditions in the state, the continued immigration of low-skilled migrants will lead to more losses of native-born internal migrants to neighboring states and metropolitan areas. However, these migrant streams will not be made up of the “best and brightest” residents that characterize most conventional migration streams.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/43483/1/11111_2005_Article_BF02208119.pd

Warped Kaluza-Klein Dark Matter

Warped compactifications of type IIB string theory contain natural dark matter candidates: Kaluza-Klein modes along approximate isometry directions of long warped throats. These isometries are broken by the full compactification, including moduli stabilization; we present a thorough survey of Kaluza-Klein mode decay rates into light supergravity modes and Standard Model particles. We find that these dark matter candidates typically have lifetimes longer than the age of the universe. Interestingly, some choices for embedding the Standard Model in the compactification lead to decay rates large enough to be observed, so this dark matter sector may provide constraints on the parameter space of the compactification.Comment: 37pp; v2. references, minor clarificatio