We are performing a uniform and unbiased imaging survey of the Large Magellanic Cloud (LMC; $7 ; 7) using the IRAC (3.6, 4.5, 5.8, and 8 m) and MIPS (24, 70, and 160 m) instruments on board the Spitzer Space Telescope in the Surveying the Agents of a Galaxy's Evolution (SAGE) survey, these agents being the interstellar medium (ISM) and stars in the LMC. This paper provides an overview of the SAGE Legacy project, including observing strategy, data processing, and initial results. Three key science goals determined the coverage and depth of the survey. The detection of diffuse ISM with column densities >1:2 ; 10 21 H cm À2 permits detailed studies of dust processes in the ISM. SAGE's point-source sensitivity enables a complete census of newly formed stars with masses >3 M that will determine the current star formation rate in the LMC. SAGE's detection of evolved stars with mass-loss rates >1 ; 10 À8 M yr À1 will quantify the rate at which evolved stars inject mass into the ISM of the LMC. The observing strategy includes two epochs in 2005, separated by 3 months, that both mitigate instrumental artifacts and constrain source variability. The SAGE data are nonproprietary. The data processing includes IRAC and MIPS pipelines and a database for mining the point-source catalogs, which will be released to the community in support of Spitzer proposal cycles 4 and 5. We present initial results on the epoch 1 data for a region near N79 and N83. The MIPS 70 and 160 m images of the diffuse dust emission of the N79/N83 region reveal a similar distribution to the gas emissions, especially the H i 21 cm emission. The measured point-source sensitivity for the epoch 1 data is consistent with expectations for the survey. The point-source counts are highest for the IRAC 3.6 m band and decrease dramatically toward longer wavelengths, A

We have determined the ratios of total to selective extinction in the near-infrared bands (J; H; K s ) toward the Galactic center from the observations of the region jlj P 2N0 and 0N5 PjbjP1N0 with the IRSF telescope and the SIRIUS camera. Using the positions of red clump stars in color-magnitude diagrams as a tracer of the extinction and reddening, we determine the average of the ratios of total to selective extinction to be A K s /E HÀK s ¼ 1:44 AE 0:01, A K s /E J ÀK s ¼ 0:494 AE 0:006, and A H /E J ÀH ¼ 1:42 AE 0:02, which are significantly smaller than those obtained in previous studies. From these ratios, we estimate that A J :A H : A K s ¼ 1:0:573 AE 0:009:0:331 AE 0:004 and E J ÀH /E HÀK s ¼ 1:72 AE 0:04, and we find that the power law A k / k À1:99AE0:02 is a good approximation over these wavelengths. Moreover, we find a small variation in A K s /E HÀK s across our survey. This suggests that the infrared extinction law changes from one line of sight to another, and the so-called universality does not necessarily hold in the infrared wavelengths.

Searches for extrasolar planets have uncovered an astonishing diversity of planetary systems, yet the frequency of solar system analogs remains unknown. The gravitational microlensing planet search method is potentially sensitive to multiple-planet systems containing analogs of all the solar system planets except Mercury. We report the detection of a multiple-planet system with microlensing. We identify two planets with masses of approximately 0.71 and approximately 0.27 times the mass of Jupiter and orbital separations of approximately 2.3 and approximately 4.6 astronomical units orbiting a primary star of mass approximately 0.50 solar mass at a distance of approximately 1.5 kiloparsecs. This system resembles a scaled version of our solar system in that the mass ratio, separation ratio, and equilibrium temperatures of the planets are similar to those of Jupiter and Saturn. These planets could not have been detected with other techniques; their discovery from only six confirmed microlensing planet detections suggests that solar system analogs may be common.

-On the basis of near-infrared imaging observations, we derived visual extinction (A V ) distribution toward ten Bok globules through measurements of both the color excess (E H−K ) and the stellar density at J, H, and K s (star count). Radial column density profiles for each globule were analyzed with the Bonnor-Ebert sphere model. Using the data of our ten globules and four globules in the literature, we investigated the stability of globules on the basis of ξ max , which characterizes the Bonnor-Ebert sphere as well as the stability of the equilibrium state against the gravitational collapse. We found that more than half of starless globules are located near the critical state (ξ max = 6.5 ± 2). Thus, we suggest that a nearly critical Bonnor-Ebert sphere characterizes the typical density structure of starless globules. Remaining starless globules show clearly unstable states (ξ max > 10). Since unstable equilibrium states are not long maintained, we expect that these globules are on the way to gravitational collapse or that they are stabilized by non-thermal support. It was also found that all the starforming globules show unstable solutions of ξ max > 10, which is consistent with the fact that they have started gravitational collapse. We investigated the evolution of a collapsing gas sphere whose initial condition is a nearly critical Bonnor-Ebert sphere. We found that the column density profiles of the collapsing sphere mimic those of the static Bonnor-Ebert spheres in unstable equilibrium. The collapsing gas sphere resembles marginally unstable Bonnor-Ebert spheres for a long time. We found that the frequency distribution of ξ max for the observed starless globules is consistent with that from model calculations of the collapsing sphere. In addition to the near-infrared observations, we carried out radio molecular line observations (C 18 O and N 2 H + ) toward the same ten globules. We confirmed that most of the globules are dominated by thermal support. The line width of each globule was used to estimate the cloud temperature including the contribution from turbulence, with which we estimated the distance to the globules from the Bonnor-Ebert model fitting.Subject headings: ISM: clouds -dust, extinction -ISM: globules -stars: formation * Recently, a low luminosity protostar was discovered toward the globule Lynds 1014, which is known to accompany no IRAS point sources, using the Spitzer Space Telescope (Young et al. 2004). Though Spitzer data are useful to clarify whether globules contain protostars or not, Spitzer data is available only for one source, CB 131, among the "IRAS-less" globules in Table 1. We briefly checked mid-infrared data of the Spitzer telescope toward CB 131 and found that there is no protostar candidates near the center of the globule. Though a source is located near the globule †

We have performed a cross-identification between Optical Gravitational Lensing Experiment II (OGLE-II) data and single-epoch Simultaneous three-colour Infrared Imager for Unbiased Surveys (SIRIUS) near-infrared (NIR) JHK survey data in the Large and Small Magellanic Clouds (LMC and SMC, respectively). After eliminating obvious spurious variables, variables with too few good data and variables that seem to have periods longer than the available baseline of the OGLE-II data, we determined the pulsation periods for 8852 and 2927 variables in the LMC and SMC, respectively.Based on these homogeneous data, we studied the pulsation properties and metallicity effects on period-K magnitude (PK) relations by comparing the variable stars in the LMC and SMC. The sample analysed here is much larger than the previous studies, and we found the following new features in the PK diagram. (1) Variable red giants in the SMC form parallel sequences on the PK plane, just like those found by Wood in the LMC. (2) Both sequences A and B of Wood have discontinuities, and they occur at the K-band luminosity of the tip of the red giant branch. (3) The sequence B of Wood separates into three independent sequences B ± and C . (4) A comparison between the theoretical pulsation models and observational data suggests that the variable red giants on sequences C and newly discovered C are pulsating in the fundamental and first overtone modes, respectively. (5) The theory cannot explain the pulsation mode of sequences A ± and B ± , and they are unlikely to be the sequences for the first and second overtone pulsators, as was previously suggested. (6) The zero-points of PK relations of Cepheids in the metal deficient SMC are fainter than those of the LMC by ≈0.1 mag but those of SMC Miras are brighter than those of the LMC by ≈0.13 mag (adopting the distance modulus offset between the LMC and SMC to be 0.49 mag and assuming the slopes of the PK relations are the same in the two galaxies), which are probably due to metallicity effects.

RNA editing catalyzed by ADAR1 and ADAR2 involves the site-specific conversion of adenosine to inosine within imperfectly duplexed RNA. ADAR1-and ADAR2-mediated editing occurs within transcripts of glutamate receptors (GluR) in the brain and in hepatitis delta virus (HDV) RNA in the liver. Although the Q/R site within the GluR-B premessage is edited more efficiently by ADAR2 than it is by ADAR1, the converse is true for the 160 site within this same transcript. ADAR1 and ADAR2 are homologs having two common functional regions, an N-terminal doublestranded RNA-binding domain and a C-terminal deaminase domain. It is neither understood why only certain adenosines within a substrate molecule serve as targets for ADARs, nor is it known which domain of an ADAR confers its specificity for particular editing sites. To assess the importance of several aspects of RNA sequence and structure on editing, we evaluated 20 different mutated substrates, derived from four editing sites, for their ability to be edited by either ADAR1 or ADAR2. We found that when these derivatives contained an A:C mismatch at the editing site, editing by both ADARs was enhanced compared to when A:A or A:G mismatches or A:U base pairs occurred at the same site. Hence substrate recognition and/or catalysis by ADARs could involve the base that opposes the edited adenosine. In addition, by using protein chimeras in which the deaminase domains were exchanged between ADAR1 and ADAR2, we found that this domain played a dominant role in defining the substrate specificity of the resulting enzyme.

We report on the correlation between the flux, color and polarization variations on time scales of daysmonths in blazars, and discuss their universal aspects. We performed monitoring of 42 blazars in the optical and near-infrared bands from 2008 to 2010 using TRISPEC attached to the "Kanata" 1.5-m telescope. We found that 28 blazars exhibited "bluer-when-brighter" trends in their whole or a part of time-series data sets. This corresponds to 88% of objects that were observed for > 10 days. Thus, our observation unambiguously confirmed that the "bluer-when-brighter" trend is common in the emission from blazar jets. This trend was apparently generated by a variation component with a constant and relatively blue color and an underlying red component. Prominent short-term flares on time scales of days-weeks tended to exhibit a spectral hysteresis; their rising phases were bluer than their decay phases around the flare maxima. In contrast to the strong flux-color correlation, the correlation of the flux and polarization degree was relatively weak; only 10 objects showed significant positive correlations. Rotations of polarization were detected only in three objects: PKS 1510−089, 3C 454.3, and PKS 1749+096, and possibly in S5 0716+714. We also investigated the dependence of the degree of variability on the luminosity and the synchrotron peak frequency, ν peak . As a result, we found that lower luminosity and higher ν peak objects had smaller variations in their amplitudes both in the flux, color, and polarization degree. Our observation suggests the presence of several distinct emitting sources, which have different variation time-scales, colors, and polarizations. We propose that the energy injection by, for example, internal shocks in relativistic shells is a major factor for blazar variations on time scales of both days and months.

Retroviral restriction factor TRIM5␣ exhibits a high degree of sequence variation among primate species. It has been proposed that this diversity is the cumulative result of ancient, lineagespecific episodes of positive selection. Here, we describe the contribution of within-species variation to the evolution of TRIM5␣. Sampling within two geographically distinct Old World monkey species revealed extensive polymorphism, including individual polymorphisms that predate speciation (shared polymorphism). In some instances, alleles were more closely related to orthologues of other species than to one another. Both silent and nonsynonymous changes clustered in two domains. Functional assays revealed consequences of polymorphism, including differential restriction of a small panel of retroviruses by very similar alleles. Together, these features indicate that the primate TRIM5␣ locus has evolved under balancing selection. Except for the MHC there are few, if any, examples of long-term balancing selection in primates. Our results suggest a complex evolutionary scenario, in which fixation of lineage-specific adaptations is superimposed on a subset of critical polymorphisms that predate speciation events and have been maintained by balancing selection for millions of years.HIV ͉ retrovirus ͉ restriction