Microlensing Characterization of Wide-Separation Planets

With their excellent photometric precision and dramatic increase in monitoring frequency, future microlensing survey experiments are expected to be sensitive to very short time-scale, isolated events caused by free-floating and wide-separation planets with mass as low as a few lunar masses. We estimate the probability of measuring the Einstein radius \theta_E for bound and free-floating planets. We carry out detailed simulations of the planetary events expected in next-generation surveys and estimate the resulting uncertainty in \theta_E for these events. We show that, for main-sequence sources and Jupiter-mass planets, the caustic structure of wide-separation planets with projected separations of < 20 AU substantially increases the probability of measuring the dimensionless source size and thus determining \theta_E compared to the case of unbound planets. In this limit where the source is much smaller than the caustic, the effective cross-section to measure \theta_E to 10% is ~25% larger than the full width of the caustic. Measurement of the lens parallax is possible for low-mass planetary events by combined observations from the ground and a satellite located in an L2 orbit; this would complete the mass measurements for such wide-separation planets. Finally, short-duration events caused by bound planets can be routinely distinguished from those caused by free-floating planets for planet-star separations < 20 AU from either the deviations due to the planetary caustic or (more often) the low-amplitude bump from the magnification due to the parent star.Comment: 10 pages including 7 figures. ApJ, in pres

On the Stability and Formation of Pillar[n]arenes: a DFT Study

The increased use of both pillar[5]arenes and pillar[6]arenes, stimulated by increasingly efficient syntheses of both, has brought forward the question as to what drives the intermediates in this Friedel-Crafts ring formation to form a pillar[5]arene, a pillar[6]arene, or any other sized macrocycle. This study sets out to answer this question by studying both the thermodynamics and kinetics involved in the absence and presence of templating solvents using high-end wB97XD/6-311G(2p,2d) DFT calculations

Interaction of CK1δ with γTuSC ensures proper microtubule assembly and spindle positioning.

Casein kinase 1δ (CK1δ) family members associate with microtubule-organizing centers (MTOCs) from yeast to humans, but their mitotic roles and targets have yet to be identified. We show here that budding yeast CK1δ, Hrr25, is a γ-tubulin small complex (γTuSC) binding factor. Moreover, Hrr25's association with γTuSC depends on its kinase activity and its noncatalytic central domain. Loss of Hrr25 kinase activity resulted in assembly of unusually long cytoplasmic microtubules and defects in spindle positioning, consistent with roles in regulation of γTuSC-mediated microtubule nucleation and the Kar9 spindle-positioning pathway, respectively. Hrr25 directly phosphorylated γTuSC proteins in vivo and in vitro, and this phosphorylation promoted γTuSC integrity and activity. Because CK1δ and γTuSC are highly conserved and present at MTOCs in diverse eukaryotes, similar regulatory mechanisms are expected to apply generally in eukaryotes

Matter-wave bistability in coupled atom-molecule quantum gases

We study the matter-wave bistability in coupled atom-molecule quantum gases, in which heteronuclear molecules are created via an interspecies Feshbach resonance involving either two-species Bose or two-species Fermi atoms at zero temperature. We show that the resonant two-channel Bose model is equivalent to the nondegenerate parametric down-conversion in quantum optics, while the corresponding Fermi model can be mapped to a quantum optics model that describes a single-mode laser field interacting with an ensemble of inhomogeneously broadened two-level atoms. Using these analogy and the fact that both models are subject to the Kerr nonlinearity due to the two-body s-wave collisions, we show that under proper conditions, the population in the molecular state in both models can be made to change with the Feshbach detuning in a bistable fashion.Comment: 6 pages, 5 figure

Tunable Supramolecular Ag+-Host Interactions in Pillar[n]arene[m]quinones and Ensuing Specific Binding to 1-Alkynes

We developed an improved, robust synthesis of a series of pillar[6]arenes with a varying number (0-3) of quinone moieties in the ring. This easy-to-control variation yielded a gradually less electron-rich cavity in going from zero to three quinone units, as shown from the strength of host-guest interactions with silver ions. Such macrocycle-Ag2 complexes themselves were shown to display an unprecedented, sharp distinction between terminal alkynes, which strongly bound to such complexes, and internal alkynes, internal alkenes and terminal alkenes, which do hardly bind

TRPV1-expressing primary afferents generate behavioral responses to pruritogens via multiple mechanisms

The mechanisms that generate itch are poorly understood at both the molecular and cellular levels despite its clinical importance. To explore the peripheral neuronal mechanisms underlying itch, we assessed the behavioral responses (scratching) produced by s.c. injection of various pruritogens in PLCβ3- or TRPV1-deficient mice. We provide evidence that at least 3 different molecular pathways contribute to the transduction of itch responses to different pruritogens: 1) histamine requires the function of both PLCβ3 and the TRPV1 channel; 2) serotonin, or a selective agonist, α-methyl-serotonin (α-Me-5-HT), requires the presence of PLCβ3 but not TRPV1, and 3) endothelin-1 (ET-1) does not require either PLCβ3 or TRPV1. To determine whether the activity of these molecules is represented in a particular subpopulation of sensory neurons, we examined the behavioral consequences of selectively eliminating 2 nonoverlapping subsets of nociceptors. The genetic ablation of MrgprD^+ neurons that represent ≈90% of cutaneous nonpeptidergic neurons did not affect the scratching responses to a number of pruritogens. In contrast, chemical ablation of the central branch of TRPV1+ nociceptors led to a significant behavioral deficit for pruritogens, including α-Me-5-HT and ET-1, that is, the TRPV1-expressing nociceptor was required, whether or not TRPV1 itself was essential. Thus, TRPV1 neurons are equipped with multiple signaling mechanisms that respond to different pruritogens. Some of these require TRPV1 function; others use alternate signal transduction pathways

Reticular pseudodrusen in late-onset retinal degeneration

PURPOSE: To characterize the association of reticular pseudodrusen (RPD) with late-onset retinal degeneration (L-ORD) using multimodal imaging. DESIGN: Prospective, two-center, longitudinal case series. SUBJECTS: Twenty-nine cases with L-ORD. METHODS: All subjects were evaluated within a three-year interval with near-infrared reflectance, fundus autofluorescence, and spectral-domain optical coherence tomography. In addition, a subset of patients also underwent indocyanine green angiography, fundus fluorescein angiography, mesopic microperimetry, and multifocal electroretinography. Main outcome measures: Prevalence, topographic distribution, and temporal phenotypic changes of RPD in L-ORD. RESULTS: A total of 29 molecularly confirmed L-ORD cases were included in this prospective study. RPD was detected in 18 cases (62%) at baseline, of which 10 were male. The prevalence of RPD varied with age. The mean age of RPD patients was 57.3±7.2 years. RPD was not seen in cases below the fifth decade (n=3 patients) or in the eighth decade (n=5 patients). RPD were found commonly in the macula with relative sparing of the fovea and were also identified in the peripheral retina. The morphology of RPD changed with follow-up. Two cases (3 eyes) demonstrated RPD regression. CONCLUSIONS: RPD is found frequently in cases with L-ORD and at a younger age than in individuals with AMD. RPD exhibits quick formation and collapse, change in type and morphology with time, relative foveal-sparing, and also has a peripheral retinal location in L-ORD

Label-Free Density Measurements of Radial Peripapillary Capillaries in the Human Retina

Radial peripapillary capillaries (RPCs) comprise a unique network of capillary beds within the retinal nerve fibre layer (RNFL) and play a critical role in satisfying the nutritional requirements of retinal ganglion cell (RGC) axons. Understanding the topographical and morphological characteristics of these networks through in vivo techniques may improve our understanding about the role of RPCs in RGC axonal health and disease. This study utilizes a novel, non-invasive and label-free optical imaging technique, speckle variance optical coherence tomography (svOCT), for quantitatively studying RPC networks in the human retina. Six different retinal eccentricities from 16 healthy eyes were imaged using svOCT. The same eccentricities were histologically imaged in 9 healthy donor eyes with a confocal scanning laser microscope. Donor eyes were subject to perfusion-based labeling techniques prior to retinal dissection, flat mounting and visualization with the microscope. Capillary density and diameter measurements from each eccentricity in svOCT and histological images were compared. Data from svOCT images were also analysed to determine if there was a correlation between RNFL thickness and RPC density. The results are as follows: (1) The morphological characteristics of RPC networks on svOCT images are comparable to histological images; (2) With the exception of the nasal peripapillary region, there were no significant differences in RPC density measurements between svOCT and histological images; (3) Capillary diameter measurements were significantly greater in svOCT images compared to histology; (4) There is a positive correlation between RPC density and RNFL thickness. The findings in this study suggest that svOCT is a reliable modality for analyzing RPC networks in the human retina. It may therefore be a valuable tool for aiding our understanding about vasculogenic mechanisms that are involved in RGC axonopathies. Further work is required to explore the reason for some of the quantitative differences between svOCT and histology

Stellar Contribution to the Galactic Bulge Microlensing Optical Depth

We estimate the optical depth to self-lensing by stars in the Galactic bulge using the HST star counts of Holtzman et al and Zoccali et al as extrapolated by Gould into the brown-dwarf and remnant regimes and deprojected along the line of sight using the model of Dwek et al. We find a self-lensing optical depth tau(bulge-bulge)=0.98 x 10^{-6}. When combined with the lensing of bulge stars by foreground stars in the disk, this yields tau(bulge-total)=1.63 x 10^{-6}, in reasonable agreement with the estimates of tau=2.13 +/- 0.40 x 10^{-6} and tau=1.08 +/- 0.30 x 10^{-6} based on observations of clump giants by the MACHO and EROS collaborations.Comment: 10 pages, including 1 figure. Submitted to Ap

Polyclonal epitope mapping reveals temporal dynamics and diversity of human antibody responses to H5N1 vaccination

Novel influenza A virus (IAV) strains elicit recall immune responses to conserved epitopes, making them favorable antigenic choices for universal influenza virus vaccines. Evaluating these immunogens requires a thorough understanding of the antigenic sites targeted by the polyclonal antibody (pAb) response, which single-particle electron microscopy (EM) can sensitively detect. In this study, we employ EM polyclonal epitope mapping (EMPEM) to extensively characterize the pAb response to hemagglutinin (HA) after H5N1 immunization in humans. Cross-reactive pAbs originating from memory B cells immediately bound the stem of HA and persisted for more than a year after vaccination. In contrast, de novo pAb responses to multiple sites on the head of HA, targeting previously determined key neutralizing sites on H5 HA, expanded after the second immunization and waned quickly. Thus, EMPEM provides a robust tool for comprehensively tracking the specificity and durability of immune responses elicited by novel universal influenza vaccine candidates