N=2 Super-Higgs, N=1 Poincare' Vacua and Quaternionic Geometry

In the context of N=2 supergravity we explain the occurrence of partial super-Higgs with vanishing vacuum energy and moduli stabilization in a model suggested by superstring compactifications on type IIB orientifolds with 3-form fluxes. The gauging of axion symmetries of the quaternionic manifold, together with the use of degenerate symplectic sections for special geometry, are the essential ingredients of the construction.Comment: 18 page

Microbial and nutrient dynamics in mangrove, reef, and seagrass waters over tidal and diurnal time scales

© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Becker, C. C., Weber, L., Suca, J. J., Llopiz, J. K., Mooney, T. A., & Apprill, A. Microbial and nutrient dynamics in mangrove, reef, and seagrass waters over tidal and diurnal time scales. Aquatic Microbial Ecology, 85, (2020): 101-119, https://doi.org/10.3354/ame01944.In coral reefs and adjacent seagrass meadow and mangrove environments, short temporal scales (i.e. tidal, diurnal) may have important influences on ecosystem processes and community structure, but these scales are rarely investigated. This study examines how tidal and diurnal forcings influence pelagic microorganisms and nutrient dynamics in 3 important and adjacent coastal biomes: mangroves, coral reefs, and seagrass meadows. We sampled for microbial (Bacteria and Archaea) community composition, cell abundances and environmental parameters at 9 coastal sites on St. John, US Virgin Islands that spanned 4 km in distance (4 coral reefs, 2 seagrass meadows and 3 mangrove locations within 2 larger bays). Eight samplings occurred over a 48 h period, capturing day and night microbial dynamics over 2 tidal cycles. The seagrass and reef biomes exhibited relatively consistent environmental conditions and microbial community structure but were dominated by shifts in picocyanobacterial abundances that were most likely attributed to diel dynamics. In contrast, mangrove ecosystems exhibited substantial daily shifts in environmental parameters, heterotrophic cell abundances and microbial community structure that were consistent with the tidal cycle. Differential abundance analysis of mangrove-associated microorganisms revealed enrichment of pelagic oligotrophic taxa during high tide and enrichment of putative sediment-associated microbes during low tide. Our study underpins the importance of tidal and diurnal time scales in structuring coastal microbial and nutrient dynamics, with diel and tidal cycles contributing to a highly dynamic microbial environment in mangroves, and time of day likely contributing to microbial dynamics in seagrass and reef biomes.This research was supported by NSF awards OCE-1536782 to T.A.M., J.K.L., and A.A. and OCE-1736288 to A.A., NOAA Cooperative Institutes award NA19O AR 4320074 to A.A. and E. Kujawinski and the Andrew W. Mellon Foundation Endowed Fund for Innovative Research to A.A

Temporal patterns of vampire bat rabies and host connectivity in Belize

In the Neotropics, vampire bats (Desmodus rotundus ) are the main reservoir host for rabies, a highly fatal encephalitis caused by viruses in the genus Lyssavirus . Although patterns of rabies virus exposure and infection have been well studied for vampire bats in South America and Mexico, exploring the ecology of vampire bat rabies in other regions is crucial for predicting risks to livestock and humans. In Belize, rabies outbreaks in livestock have increased in recent years, underscoring the need for systematic data on viral dynamics in vampire bats. In this study, we examine the first three years of a longitudinal study on the ecology of vampire bat rabies in northern Belize. Rabies seroprevalence in bats was high across years (29%–80%), suggesting active and endemic virus circulation. Across two locations, the seroprevalence time series per site were inversely related and out of phase by at least a year. Microsatellite data demonstrated historic panmixia of vampire bats, and mark–recapture detected rare but contemporary inter‐site dispersal. This degree of movement could facilitate spatial spread of rabies virus but is likely insufficient to synchronize infection dynamics, which offers one explanation for the observed phase lag in seroprevalence. More broadly, our analyses suggest frequent transmission of rabies virus within and among vampire bat roosts in northern Belize and highlight the need for future spatiotemporal, phylogenetic and ecological studies of vampire bat rabies in Central America

A Survey of z>5.7 Quasars in the Sloan Digital Sky Survey II: Discovery of Three Additional Quasars at z>6

We present the discovery of three new quasars at z>6 in 1300 deg^2 of SDSS imaging data, J114816.64+525150.3 (z=6.43), J104845.05+463718.3 (z=6.23) and J163033.90+401209.6 (z=6.05). The first two objects have weak Ly alpha emission lines; their redshifts are determined from the positions of the Lyman break. They are only accurate to 0.05 and could be affected by the presence of broad absorption line systems. The last object has a Ly alpha strength more typical of lower redshift quasars. Based on a sample of six quasars at z>5.7 that cover 2870 deg^2 presented in this paper and in Paper I, we estimate the comoving density of luminous quasars at z 6 and M_{1450} < -26.8 to be (8 +/- 3)x10^{-10} Mpc^{-3} (for H_0 = 50 km/s/Mpc, Omega = 1). HST imaging of two z>5.7 quasars and high-resolution ground-based images (seeing 0.4'') of three additional z>5.7 quasars show that none of them is gravitationally lensed. The luminosity distribution of the high-redshfit quasar sample suggests the bright end slope of the quasar luminosity function at z 6 is shallower than Psi L^{-3.5} (2-sigma), consistent with the absence of strongly lensed objects.Comment: AJ in press (Apr 2003), 26 pages, 9 figure

4-D gauged supergravity analysis of Type IIB vacua on K3×T2/Z2K3\times T^2/Z_2

We analyze $N=2,1,0$ vacua of type IIB string theory on $K3\times T^2/Z_2$ in presence of three-form fluxes from a four dimensional supergravity viewpoint. The quaternionic geometry of the $K3$ moduli space together with the special geometry of the NS and R-R dilatons and of the $T^2$-complex structure moduli play a crucial role in the analysis. The introduction of fluxes corresponds to a particular gauging of N=2, D=4 supergravity. Our results agree with a recent work of Tripathy and Trivedi. The present formulation shows the power of supergravity in the study of effective theories with broken supersymmetry.Comment: AMS-LaTeX, 29 page

The Economic Resource Receipt of New Mothers

U.S. federal policies do not provide a universal social safety net of economic support for women during pregnancy or the immediate postpartum period but assume that employment and/or marriage will protect families from poverty. Yet even mothers with considerable human and marital capital may experience disruptions in employment, earnings, and family socioeconomic status postbirth. We use the National Survey of Families and Households to examine the economic resources that mothers with children ages 2 and younger receive postbirth, including employment, spouses, extended family and social network support, and public assistance. Results show that many new mothers receive resources postbirth. Marriage or postbirth employment does not protect new mothers and their families from poverty, but education, race, and the receipt of economic supports from social networks do

Self-related consequences of death fear and death denial

This study explores self-related outcomes (e.g., esteem, self-concept clarity, existential well-being) as a function of the interaction between self-reported levels of death fear and death denial. Consistent with the idea that positive existential growth can come from individuals facing, rather than denying, their mortality (Cozzolino, 2006), the authors observed that not fearing and denying death can bolster important positive components of the self. That is, individuals low in death denial and death fear evidenced an enhanced self that is valued, clearly conceived, efficacious, and that has meaning and purpose

Evolution of the Ionizing Background and the Epoch of Reionization from the Spectra of z~6 Quasars

We study the process of cosmic reionization and estimate the ionizing background in the IGM using the Lyman series absorption in the spectra of the four quasars at 5.7<z<6.3 discovered by the SDSS. We derive the evolution of the ionizing background at high redshifts, using both semi-analytic techniques and cosmological simulations to model the density fluctuations in the IGM. The existence of the complete Ly alpha Gunn-Peterson trough in the spectrum of the z=6.28 quasar SDSS 1030+0524 indicates a photoionization rate Gamma_{-12} at z~6 lower than 0.08, at least a factor of 6 smaller than the value at z~3. The Ly beta and Ly gamma Gunn-Peterson troughs give an even stronger limit Gamma_{-12}<0.02 due to their smaller oscillator strengths, indicating that the ionizing background in the IGM at z~6 is more than 20 times lower than that at z~3. Meanwhile, the volume-averaged neutral hydrogen fraction increases from 10^{-5} at z~3 to >10^{-3} at z~6. At this redshift, the mass-averaged neutral hydrogen fraction is larger than 1%; the mildly overdense regions (delta > 3) are still mostly neutral and the comoving mean free path of ionizing photons is shorter than 8 Mpc. Comparison with simulations of cosmological reionization shows that the observed properties of the IGM at z~6 are typical of those in the era at the end of the overlap stage of reionization when the individual HII regions merge. Thus, z~6 marks the end of the reionization epoch. The redshift of reionization constrains the small scale power of the mass density fluctuations and the star forming efficiency of the first generation of objects.Comment: AJ accepted, 27 pages; minor change

Interferon regulatory factor 8-deficiency determines massive neutrophil recruitment but T cell defect in fast growing granulomas during tuberculosis

Following Mycobacterium tuberculosis (Mtb) infection, immune cell recruitment in lungs is pivotal in establishing protective immunity through granuloma formation and neogenesis of lymphoid structures (LS). Interferon regulatory factor-8 (IRF-8) plays an important role in host defense against Mtb, although the mechanisms driving anti-mycobacterial immunity remain unclear. In this study, IRF-8 deficient mice (IRF-8−/−) were aerogenously infected with a low-dose Mtb Erdman virulent strain and the course of infection was compared with that induced in wild-type (WT-B6) counterparts. Tuberculosis (TB) progression was examined in both groups using pathological, microbiological and immunological parameters. Following Mtb exposure, the bacterial load in lungs and spleens progressed comparably in the two groups for two weeks, after which IRF-8−/− mice developed a fatal acute TB whereas in WT-B6 the disease reached a chronic stage. In lungs of IRF-8−/−, uncontrolled growth of pulmonary granulomas and impaired development of LS were observed, associated with unbalanced homeostatic chemokines, progressive loss of infiltrating T lymphocytes and massive prevalence of neutrophils at late infection stages. Our data define IRF-8 as an essential factor for the maintenance of proper immune cell recruitment in granulomas and LS required to restrain Mtb infection. Moreover, IRF-8−/− mice, relying on a common human and mouse genetic mutation linked to susceptibility/severity of mycobacterial diseases, represent a valuable model of acute TB for comparative studies with chronically-infected congenic WT-B6 for dissecting protective and pathological immune reactions

Advantages of cone beam computed tomography (CBCT) in the orthodontic treatment planning of cleidocranial dysplasia patients: a case report

Our aim was to discuss, by presenting a case, the possibilities connected to the use of a CBCT exam in the dental evaluation of patients with Cleidocranial Dysplasia (CCD), an autosomal dominant skeletal dysplasia with delayed exfoliation of deciduous and eruption of permanent teeth and multiple supernumeraries, often impacted. We think that CBCT in this patient was adequate to accurately evaluate impacted teeth position and anatomy, resulting thus useful both in the diagnostic process and in the treatment planning, with an important reduction in the radiation dose absorbed by the patient