59 research outputs found
Frasier syndrome: a cause of focal segmental glomerulosclerosis in a 46,XX female
The description of Frasier syndrome until now has been restricted to XY females with gonadal dysgenesis, progressive glomerulopathy, and a significant risk of gonadoblastoma. Mutations in the donor splice site in intron 9 of the Wilms\u27 tumor (WT1) gene have been shown to cause Frasier syndrome and are distinct from WT1 exon mutations associated with Denys-Drash syndrome. The WT1 gene, which is essential for normal kidney and gonadal development, encodes a zinc finger transcription factor. The intron 9 alternative splice donor site mutation seen in Frasier syndrome leads to loss of three amino acids (+KTS isoform), thus disrupting the normal ratio of the +KTS/-KTS isoforms critical for proper gonadal and renal development. This study examines two sisters with identical intron 9 mutations. The proband carries a classic diagnosis of Frasier syndrome with 46,XY gonadal dysgenesis, whereas her sister has progressive glomerulopathy but a 46,XX karyotype and normal female development. This indicates that the proper WT1 isoform ratio is critical for renal and testicular development, but apparently does not affect either ovarian development or function. It is proposed that the clinical definition of Frasier syndrome should be broadened to include 46,XX females with normal genital development and focal segmental glomerulosclerosis associated with a WT1 intron 9 donor splice site mutation. Nephrologists need to consider the possibility of this heritable syndrome in evaluation of females with focal segmental glomerulosclerosis and to consider their risk for gonadal malignancy, as well as the risk for kidney disease, gonadal dysgenesis, and malignancy in their offspring
Utility of sedation for young children undergoing dimercaptosuccinic acid renal scans
No studies have examined whether use of sedation during a Tc-99m dimercaptosuccinic acid (DMSA) renal scan reduces patient discomfort
Fermi Large Area Telescope Constraints on the Gamma-ray Opacity of the Universe
The Extragalactic Background Light (EBL) includes photons with wavelengths
from ultraviolet to infrared, which are effective at attenuating gamma rays
with energy above ~10 GeV during propagation from sources at cosmological
distances. This results in a redshift- and energy-dependent attenuation of the
gamma-ray flux of extragalactic sources such as blazars and Gamma-Ray Bursts
(GRBs). The Large Area Telescope onboard Fermi detects a sample of gamma-ray
blazars with redshift up to z~3, and GRBs with redshift up to z~4.3. Using
photons above 10 GeV collected by Fermi over more than one year of observations
for these sources, we investigate the effect of gamma-ray flux attenuation by
the EBL. We place upper limits on the gamma-ray opacity of the Universe at
various energies and redshifts, and compare this with predictions from
well-known EBL models. We find that an EBL intensity in the optical-ultraviolet
wavelengths as great as predicted by the "baseline" model of Stecker et al.
(2006) can be ruled out with high confidence.Comment: 42 pages, 12 figures, accepted version (24 Aug.2010) for publication
in ApJ; Contact authors: A. Bouvier, A. Chen, S. Raino, S. Razzaque, A.
Reimer, L.C. Reye
Protest Cycles and Political Process: American Peace Movements in the Nuclear Age
Since the dawn of the nuclear age small groups of activists have consistently protested both the content of United States national security policy, and the process by which it is made. Only occasionally, however, has concern about nuclear weapons spread beyond these relatively marginal groups, generated substantial public support, and reached mainstream political institutions. In this paper, I use histories of peace protest and analyses of the inside of these social movements and theoretical work on protest cycles to explain cycles of movement engagement and quiescence in terms of their relation to external political context, or the "structure of political opportunity." I begin with a brief review of the relevant literature on the origins of movements, noting parallels in the study of interest groups. Building on recent literature on political opportunity structure, I suggest a theoretical framework for understanding the lifecycle of a social movement that emphasizes the interaction between activist choices and political context, proposing a six-stage process through which challenging movements develop. Using this theoretical framework I examine the four cases of relatively broad antinuclear weapons mobilization in postwar America. I conclude with a discussion of movement cycles and their relation to political alignment, public policy, and institutional politics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68552/2/10.1177_106591299304600302.pd
Strong gravitational lensing probes of the particle nature of dark matter
There is a vast menagerie of plausible candidates for the constituents of
dark matter, both within and beyond extensions of the Standard Model of
particle physics. Each of these candidates may have scattering (and other)
cross section properties that are consistent with the dark matter abundance,
BBN, and the most scales in the matter power spectrum; but which may have
vastly different behavior at sub-galactic "cutoff" scales, below which dark
matter density fluctuations are smoothed out. The only way to quantitatively
measure the power spectrum behavior at sub-galactic scales at distances beyond
the local universe, and indeed over cosmic time, is through probes available in
multiply imaged strong gravitational lenses. Gravitational potential
perturbations by dark matter substructure encode information in the observed
relative magnifications, positions, and time delays in a strong lens. Each of
these is sensitive to a different moment of the substructure mass function and
to different effective mass ranges of the substructure. The time delay
perturbations, in particular, are proving to be largely immune to the
degeneracies and systematic uncertainties that have impacted exploitation of
strong lenses for such studies. There is great potential for a coordinated
theoretical and observational effort to enable a sophisticated exploitation of
strong gravitational lenses as direct probes of dark matter properties. This
opportunity motivates this white paper, and drives the need for: a) strong
support of the theoretical work necessary to understand all astrophysical
consequences for different dark matter candidates; and b) tailored
observational campaigns, and even a fully dedicated mission, to obtain the
requisite data.Comment: Science white paper submitted to the Astro2010 Decadal Cosmology &
Fundamental Physics Science Frontier Pane
Galaxies Going Bananas: Inferring the 3D Geometry of High-Redshift Galaxies with JWST-CEERS
The 3D geometry of high-redshift galaxies remains poorly understood. We build
a differentiable Bayesian model and use Hamiltonian Monte Carlo to efficiently
and robustly infer the 3D shapes of star-forming galaxies in JWST-CEERS
observations with at . We reproduce
previous results from HST-CANDELS in a fraction of the computing time and
constrain the mean ellipticity, triaxiality, size and covariances with samples
as small as galaxies. We find high 3D ellipticities for all
mass-redshift bins suggesting oblate (disky) or prolate (elongated) geometries.
We break that degeneracy by constraining the mean triaxiality to be for
dwarfs at (favoring the prolate scenario),
with significantly lower triaxialities for higher masses and lower redshifts
indicating the emergence of disks. The prolate population traces out a
``banana'' in the projected diagram with an excess of low ,
large galaxies. The dwarf prolate fraction rises from at
to at . If these are disks, they cannot be
axisymmetric but instead must be unusually oval (triaxial) unlike local
circular disks. We simultaneously constrain the 3D size-mass relation and its
dependence on 3D geometry. High-probability prolate and oblate candidates show
remarkably similar S\'ersic indices (), non-parametric morphological
properties and specific star formation rates. Both tend to be visually
classified as disks or irregular but edge-on oblate candidates show more dust
attenuation. We discuss selection effects, follow-up prospects and theoretical
implications.Comment: Submitted to ApJ, main body is 35 pages of which ~half are full-page
figures, comments welcom
A horizon scan of global biological conservation issues for 2024
We present the results of our 15th horizon scan of novel issues that could influence biological conservation in the future. From an initial list of 96 issues, our international panel of scientists and practitioners identified 15 that we consider important for societies worldwide to track and potentially respond to. Issues are novel within conservation or represent a substantial positive or negative step-change with global or regional extents. For example, new sources of hydrogen fuel and changes in deep-sea currents may have profound impacts on marine and terrestrial ecosystems. Technological advances that may be positive include benchtop DNA printers and the industrialisation of approaches that can create high-protein food from air, potentially reducing the pressure on land for food production
Long-term thermal sensitivity of Earth’s tropical forests
The sensitivity of tropical forest carbon to climate is a key uncertainty in predicting global climate change. Although short-term drying and warming are known to affect forests, it is unknown if such effects translate into long-term responses. Here, we analyze 590 permanent plots measured across the tropics to derive the equilibrium climate controls on forest carbon. Maximum temperature is the most important predictor of aboveground biomass (−9.1 megagrams of carbon per hectare per degree Celsius), primarily by reducing woody productivity, and has a greater impact per °C in the hottest forests (>32.2°C). Our results nevertheless reveal greater thermal resilience than observations of short-term variation imply. To realize the long-term climate adaptation potential of tropical forests requires both protecting them and stabilizing Earth’s climate
Consistent patterns of common species across tropical tree communities
Trees structure the Earth’s most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1,2,3,4,5,6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth’s 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world’s most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.Publisher PDFPeer reviewe
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