431 research outputs found
Complex organic molecules in protostellar environments in the SKA era
Molecular complexity builds up at each step of the Sun-like star formation
process, starting from simple molecules and ending up in large polyatomic
species. Complex organic molecules (COMs; such as methyl formate, HCOOCH,
dymethyl ether, CHOCH, formamide, NHCHO, or glycoaldehyde,
HCOCHOH) are formed in all the components of the star formation recipe
(e.g. pre-stellar cores, hot-corinos, circumstellar disks, shocks induced by
fast jets), due to ice grain mantle sublimation or sputtering as well as
gas-phase reactions. Understanding in great detail the involved processes is
likely the only way to predict the ultimate molecular complexity reached in the
ISM, as the detection of large molecules is increasingly more difficult with
the increase of the number of atoms constituting them.
Thanks to the recent spectacular progress of astronomical observations, due
to the Herschel (sub-mm and IR), IRAM and SMA (mm and sub-mm), and NRAO (cm)
telescopes, an enormous activity is being developed in the field of
Astrochemistry, extending from astronomical observatories to chemical
laboratories. We are involved in several observational projects providing
unbiased spectral surveys (in the 80-300 and 500-2000 GHz ranges) with
unprecedented sensitivity of templates of dense cores and protostars. Forests
of COM lines have been detected. In this chapter we will focus on the chemistry
of both cold prestellar cores and hot shocked regions, (i) reviewing results
and open questions provided by mm-FIR observations, and (ii) showing the need
of carrying on the observations of COMs at lower frequencies, where SKA will
operate. We will also emphasize the importance of analysing the spectra by the
light of the experimental studies performed by our team, who is investigating
the chemical effects induced by ionising radiation bombarding astrophysically
relevant ices.Comment: 18 pages, 8 figure
PCSK9-D374Y mediated LDL-R degradation can be functionally inhibited by EGF-A and truncated EGF-A peptides: An in vitro study
Background and aims: Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low density lipoprotein receptor (LDLR) through the LDLR epidermal growth factor-like repeat A (EGF-A) domain and induces receptor internalization and degradation. PCSK9 has emerged as a novel therapeutic target for hypercholesterolemia. Clinical studies with PCSK9 inhibiting antibodies have demonstrated strong LDL-c lowering effects, but other therapeutic approaches using small molecule inhibitors for targeting PCSK9 functions may offer supplementary therapeutic options. The aim of our study was to evaluate the effect of synthetic EGF-A analogs on mutated (D374Y) PCSK9-D374Y mediated LDLR degradation in vitro. Methods: Huh7 human hepatoma cells were transiently transfected to overexpress the gain-of-function D374Y PCSK9 mutation, which has been associated with severe hypercholesterolemia in humans. Results: Transient transfection of cells with PCSK9-D374Y expression vector very effectively enhanced degradation of mature LDLR in Huh7. Treatment with both EGF-A and EGF-A truncated peptides inhibited this effect and showed increased LDLR protein in Huh7 cells transfected with PCSK9-D374Y in a clear concentration dependent manner. Huh7 transfected cells treated with increasing concentration of EGF-A analogs also showed an increase internalization of labeled Dil-LDL. Conclusions: The result of our study shows that EGF-A analogs are able to effectively hamper the enhanced degradation of LDLR in liver cells expressing PCSK9-D374Y
Identifying Youth at Clinical High Risk: Whatâs the Emotional Impact?
Background:
Early intervention in major mental illness promises to improve the lives of those identified.
âą But could identifying youth as at clinical high risk (CHR) for psychosis also do harm given that the majority never develop a psychotic disorder?
âą Could telling someone they are at risk for psychosis activate internalized stigma that has been associated with increased emotional distress, social withdrawal, non-engagement in treatment, and suicide risk in CHR youth?
âą Within the context of a larger study of stigma in CHR, we compared emotional responses to the CHR concept assessed before and after clinical feedback by study clinicians.
âą Some participants had been told of their risk prior to study entry; others had not
The USNO-B Catalog
USNO-B is an all-sky catalog that presents positions, proper motions,
magnitudes in various optical passbands, and star/galaxy estimators for
1,042,618,261 objects derived from 3,643,201,733 separate observations. The
data were obtained from scans of 7,435 Schmidt plates taken for the various sky
surveys during the last 50 years. USNO-B1.0 is believed to provide all-sky
coverage, completeness down to V = 21, 0.2 arcsecond astrometric accuracy at
J2000, 0.3 magnitude photometric accuracy in up to five colors, and 85%
accuracy for distinguishing stars from non-stellar objects. A brief discussion
of various issues is given here, but the actual data are available from
http://www.nofs.navy.mil and other sites.Comment: Accepted by Astronomical Journa
Recommended from our members
Overview of the results of the organics PET Study of the cometary samples returned from comet Wild 2 by the Stardust mission
This presenation will provide an overview of the efforts and results produced by the Organics Preliminary Examination Team during their studies of the samples returned from comet Wild 2 by the Stardust spacecraft
Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research
This review discusses the current status of supermassive black hole research,
as seen from a purely observational standpoint. Since the early '90s, rapid
technological advances, most notably the launch of the Hubble Space Telescope,
the commissioning of the VLBA and improvements in near-infrared speckle imaging
techniques, have not only given us incontrovertible proof of the existence of
supermassive black holes, but have unveiled fundamental connections between the
mass of the central singularity and the global properties of the host galaxy.
It is thanks to these observations that we are now, for the first time, in a
position to understand the origin, evolution and cosmic relevance of these
fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this
version contains low resolution figures. The full resolution version can be
downloaded from http://www.physics.rutgers.edu/~lff/publications.htm
Treatment with COLchicine in hospitalized patients affected by COVID-19: The COLVID-19 trial
Objective: To evaluate whether the addition of colchicine to standard of care (SOC) results in better outcomes in hospitalized patients with COVID-19. Design: This interventional, multicenter, randomized, phase 2 study, evaluated colchicine 1.5 mg/day added to SOC in hospitalized COVID-19 patients (COLVID-19 trial) and 227 patients were recruited. The primary outcome was the rate of critical disease in 30 days defined as need of mechanical ventilation, intensive care unit (ICU), or death. Results: 152 non-anti-SARS-CoV-2-vaccinated patients (colchicine vs controls: 77vs75, mean age 69.1±13.1 vs 67.9±15 years, 39% vs 33.3% females, respectively) were analyzed. There was no difference in co-primary end-points between patients treated with colchicine compared to controls (mechanical ventilation 5.2% vs 4%, ICU 1.3% vs 5.3%, death 9.1% vs 6.7%, overall 11 (14.3%) vs 10 (13.3%) patients, P=ns, respectively). Mean time to discharge was similar (colchicine vs controls 14.1±10.4 vs 14.7±8.1 days). Older age (>60 years, P=0.025), P/F<275 mmHg (P=0.005), AST>40 U/L (P<0.001), pre-existent heart (P=0.02), lung (P=0.003), upper-gastrointestinal (P=0.014), lower-gastrointestinal diseases (P=0.009) and cancer (P=0.008) were predictive of achieving the primary outcome. Diarrhoea (9.1% vs 0%, p=0.0031) and increased levels of AST at 6 days (76.9±91.8 vs 33.5±20.7 U/l, P=0.016) were more frequent in the colchicine group. Conclusion: Colchicine did not reduce the rate and the time to the critical stage. Colchicine was relatively safe although adverse hepatic effects require caution. We confirm that older (>60 years) patients with comorbidities are characterized by worse outcome
Recommended from our members
Early fluid migration and alteration fronts in the CM chondrite Reckling Peak 17085
Reckling Peak (RKP) 17085 is a newly classified Antarctic CM chondrite that preserves a complex alteration history characterized by mild aqueous alteration (CM2.7), overprinted by a shortâlived thermal metamorphic event (heating stage III [<750°C]), and affected by lowâgrade terrestrial weathering. This meteorite contains abundant Feârich bands within the fineâgrained matrix, composed of micronâscale Feâoxyhydroxide minerals. They are interpreted as âalteration frontsâ arising due to the dissolution and transport of Fe (typically <500 ÎŒm) before being abruptly deposited. This alteration texture is relatively rare among hydrated carbonaceous chondrites, with only five reported instances to date (Murchison, Murray, Allan Hills 81002, Miller Range 07687, and Northwest Africa 5958). Evidence from RKP 17085 suggests that early aqueous alteration operated as multiple geochemically isolated microenvironments, which moved outwards from local point sources within the matrix. Low permeability fineâgrained rims on chondrules appear to have acted as barriers to fluid flow, controlling the migration of fluid across the parent body. Furthermore, the higher porosity regions within the altered fineâgrained matrix represent either void space generated by the dehydration of hydrated minerals during postâhydration metamorphism and/or sites of ice accretion (waterâice or Câbearing ices) preserved within a mildly altered primitive matrix
Prefigurative politics between ethical practice and absent promise
'Prefigurative politics' has become a popular term for social movements' ethos of unity between means and ends, but its conceptual genealogy has escaped attention. This article disentangles two components: an ethical revolutionary practice, chiefly indebted to the anarchist tradition, which fights domination while directly constructing alternatives; and prefiguration as a recursive temporal framing, unknowingly drawn from Christianity, in which a future radiates backwards on its past. Tracing prefiguration from the Church Fathers to politicised re-surfacings in the Diggers and the New Left, I associate it with Koselleck's 'process of reassurance' in a pre-ordained historical path. Contrasted to recursive prefiguration are the generative temporal framings couching defences of means-ends unity in the anarchist tradition. These emphasised the path dependency of revolutionary social transformation and the ethical underpinnings of anti-authoritarian politics. Misplaced recursive terminology, I argue, today conveniently distracts from the generative framing of means-ends unity, as the promise of revolution is replaced by that of environmental and industrial collapse. Instead of prefiguration, I suggest conceiving of means-ends unity in terms of Bloch's 'concrete utopia', and associating it with 'anxious' and 'catastrophic' forms of hope
Dust Processing in Disks around T Tauri Stars
The 8-14 micron emission spectra of 12 T Tauri stars in the Taurus/Auriga
dark clouds and in the TW Hydrae association obtained with the Infrared
Spectrograph (IRS; The IRS is a collaborative venture between Cornell
University and Ball Aerospace Corporation funded by NASA through the Jet
Propulsion Laboratory and the Ames Research Center.) on board Spitzer are
analyzed. Assuming the 10 micron features originate from silicate grains in the
optically thin surface layers of T Tauri disks, the 8-14 micron dust emissivity
for each object is derived from its Spitzer spectrum. The emissivities are fit
with the opacities of laboratory analogs of cosmic dust. The fits include small
nonspherical grains of amorphous silicates (pyroxene and olivine), crystalline
silicates (forsterite and pyroxene), and quartz, together with large fluffy
amorphous silicate grains. A wide range in the fraction of crystalline silicate
grains as well as large silicate grains among these stars are found. The dust
in the transitional-disk objects CoKu Tau/4, GM Aur, and DM Tau has the
simplest form of silicates, with almost no hint of crystalline components and
modest amounts of large grains. This indicates that the dust grains in these
objects have been modified little from their origin in the interstellar medium.
Other stars show various amounts of crystalline silicates, similar to the wide
dispersion of the degree of crystallinity reported for Herbig Ae/Be stars of
mass <2.5 solar masses. Late spectral type, low-mass stars can have significant
fractions of crystalline silicate grains. Higher quartz mass fractions often
accompany low amorphous olivine-to-amorphous pyroxene ratios. It is also found
that lower contrast of the 10 micron feature accompanies greater crystallinity.Comment: AASTEX, 39 pages text, 14 figures, 4 tables, scheduled to be
published July 2006 in the Astrophysical Journa
- âŠ