86 research outputs found
Configuration development study of the OSU 1 hypersonic research vehicle
In an effort to insure the future development of hypersonic cruise aircraft, the possible vehicle configurations were examined to develop a single-stage-to-orbit hypersonic research vehicle (HRV). Based on the needs of hypersonic research and development, the mission goals and requirements are determined. A body type is chosen. Three modes of propulsion and two liquid rocket fuels are compared, followed by the optimization of the body configuration through aerodynamic, weight, and trajectory studies. A cost analysis is included
Neutral hydrogen in dwarf galaxies. II. The kinematics of HI
This paper is the second in a series presenting a sample of 29 late-type
dwarf galaxies observed with the Westerbork Synthesis Radio Telescope in the
21-cm line of neutral hydrogen (HI). Here we present rotation curves, maps of
the velocity field and maps of the velocity dispersion across the sample
galaxies.Comment: 16 pages; accepted by A&
Chemical abundances in quasar host galaxies and environments from narrow absorption line systems
We determined C, N and alpha-element relative abundances in the gas
surrounding six QSOs at an average redshift of ~ 2.4, by studying six
narrow associated absorption systems in UVES high-resolution spectra. We found
five systems with a metallicity (measured by C/H) consistent or above the solar
value. The ionization structure observed in the associated systems is clearly
different from that of the intervening ones, indicating that the associated
systems are influenced by the strong UV flux from the QSO. There is a possible
correlation (anticorrelation) between [N/C] ([Si/C]) and [C/H] of the studied
associated systems, and [N/C] >= 0 when [C/H] >= 0. We have compared these
observational results with the predictions of a model simulating the joint
evolution of QSOs and their spheroidal hosts. The agreement turns out to be
very good, in particular, the case envisaging massive haloes and high
star-formation rates recovers both the correlation between [N/C] and [C/H] and
the anticorrelation for [Si/C] vs. [C/H]. Narrow associated absorption systems
prove to be powerful tracers of the chemical abundances in gas belonging to
high redshift spheroidal galaxies. The outflow of this same gas, triggered by
the QSO feedback, is probably going to contribute to the early enrichment of
the surrounding intergalactic medium. A larger statistics, possibly increasing
the number of ionisation stages, chemical elements and the redshift range,
would allow us to put firm constraints on detailed chemical evolution models of
galaxies at high redshifts.Comment: 13 pages, 10 figures, submitted to MNRAS. Revised version after
referee comments. Some changes in the paper structure, critical revision of
errors, conclusions unchange
Improved PCR based methods for detecting C9orf72 hexanucleotide repeat expansions
Due to the GC-rich, repetitive nature of C9orf72 hexanucleotide repeat expansions, PCR based detection methods are challenging. Several limitations of PCR have been reported and overcoming these could help to define the pathogenic range. There is also a need to develop improved repeat-primed PCR assays which allow detection even in the presence of genomic variation around the repeat region. We have optimised PCR conditions for the C9orf72 hexanucleotide repeat expansion, using betaine as a co-solvent and specific cycling conditions, including slow ramping and a high denaturation temperature. We have developed a flanking assay, and repeat-primed PCR assays for both 3′ and 5′ ends of the repeat expansion, which when used together provide a robust strategy for detecting the presence or absence of expansions greater than ∼100 repeats, even in the presence of genomic variability at the 3′ end of the repeat. Using our assays, we have detected repeat expansions in 47/442 Scottish ALS patients. Furthermore, we recommend the combined use of these assays in a clinical diagnostic setting
Dynamics of Starbursting Dwarf Galaxies. II. UGC 4483
UGC 4483 is a nearby Blue Compact Dwarf (BCD) galaxy. HST observations have
resolved the galaxy into single stars and this has led to the derivation of its
star formation history and to a direct estimate of its stellar mass. We have
analysed archival VLA observations of the 21 cm line and found that UGC 4483
has a steeply-rising rotation curve which flattens in the outer parts at a
velocity of ~20 km/s. Radial motions of ~5 km/s may also be present. As far as
we know, UGC 4483 is the lowest-mass galaxy with a differentially rotating HI
disk. The steep rise of the rotation curve indicates that there is a strong
central concentration of mass. We have built mass models using the HST
information on the stellar mass to break the disk-halo degeneracy: old stars
contribute ~50 of the observed rotation velocity at 2.2 disk scale-lengths.
Baryons (gas and stars) constitute an important fraction of the total dynamical
mass. These are striking differences with respect to typical dwarf irregular
galaxies (dIrrs), which usually have slowly-rising rotation curves and are
thought to be entirely dominated by dark matter. BCDs appear to be different
from non-starbursting dIrrs in terms of their HI and stellar distributions and
their internal dynamics. To their high central surface brightnesses and high
central HI densities correspond strong central rotation-velocity gradients.
This implies that the starburst is closely related with the gravitational
potential and the concentration of gas. We discuss the implications of our
results on the properties of the progenitors/descendants of BCDs.Comment: Published on Astronomy & Astrophysics (11 pages, 10 figures). Typos
fixe
Prescribing databases can be used to monitor trends in opioid analgesic prescribing in Australia
Objective: There has been increased use of prescription opioid analgesics in Australia in the past 20 years with increasing evidence of related problems. A number of data sources collect information about the dispensed prescribing for opioid medications, but little is known about the extent to which these data sources agree on levels of opioid prescribing. Methods: In Queensland, all opioid prescriptions (S8 prescriptions) dispensed by community pharmacies must be submitted to the Drugs of Dependence Unit (DDU). This potentially comprises a gold standard' against which other data sources may be judged. There are two national data sources: the Pharmaceutical Benefits Schedule (PBS) for all medications subsidised by government; and an annual national survey of representative pharmacies, which assesses non-subsidised opioid prescribing. We examined the agreement between these data sources. Results: The three data sources provided consistent estimates of use over time. The correlations between different data sources were high for most opioid analgesics. There was a substantial (60%) increase in the dispensed use of opioid analgesics and a 180% increase in the dispensed use of oxycodone over the period 20022009. Tramadol was the most used opioid-like medication. Conclusions: Since 2002 different data sources reveal similar trends, namely a substantial increase in the prescribing of opioid medications. With few exceptions, the conclusions derived from using any of these data sources were similar. Implications: Improved access to PBS data for relevant stakeholders could provide an efficient and cost-effective way to monitor use of prescription opioid analgesics
Elemental Abundances in the Broad Emission Line Region of Quasars at Redshifts larger than 4
We present observations of 11 high redshift quasars (3.9 \la z \la 5.0)
observed with low spectral resolution in the restframe ultraviolet using FORS 1
at the VLT UT 1. The emission-line fluxes of strong permitted and
intercombination ultraviolet emission lines are measured to estimate the
chemical composition of the line emitting gas. Comparisons to photoionization
calculations indicate gas metallicities in the broad emission line region in
the range of solar to several times solar. The average of the mean metallicity
of each high-z quasar in this sample is . Assuming a
chemical evolution time scale of Gyrs, we derive
a redshift of for the onset of the first major star
formation episode (H km s Mpc, ,
), corresponding to an age of the universe of several
yrs at this epoch. We note that this epoch is also supposed to be the
era of re-ionization of the universe.Comment: 9 pages, 4 figures. accepted for publication in Astron.&Astrophy
Cabbage and fermented vegetables : From death rate heterogeneity in countries to candidates for mitigation strategies of severe COVID-19
Large differences in COVID-19 death rates exist between countries and between regions of the same country. Some very low death rate countries such as Eastern Asia, Central Europe, or the Balkans have a common feature of eating large quantities of fermented foods. Although biases exist when examining ecological studies, fermented vegetables or cabbage have been associated with low death rates in European countries. SARS-CoV-2 binds to its receptor, the angiotensin-converting enzyme 2 (ACE2). As a result of SARS-CoV-2 binding, ACE2 downregulation enhances the angiotensin II receptor type 1 (AT(1)R) axis associated with oxidative stress. This leads to insulin resistance as well as lung and endothelial damage, two severe outcomes of COVID-19. The nuclear factor (erythroid-derived 2)-like 2 (Nrf2) is the most potent antioxidant in humans and can block in particular the AT(1)R axis. Cabbage contains precursors of sulforaphane, the most active natural activator of Nrf2. Fermented vegetables contain many lactobacilli, which are also potent Nrf2 activators. Three examples are: kimchi in Korea, westernized foods, and the slum paradox. It is proposed that fermented cabbage is a proof-of-concept of dietary manipulations that may enhance Nrf2-associated antioxidant effects, helpful in mitigating COVID-19 severity.Peer reviewe
Nrf2-interacting nutrients and COVID-19 : time for research to develop adaptation strategies
There are large between- and within-country variations in COVID-19 death rates. Some very low death rate settings such as Eastern Asia, Central Europe, the Balkans and Africa have a common feature of eating large quantities of fermented foods whose intake is associated with the activation of the Nrf2 (Nuclear factor (erythroid-derived 2)-like 2) anti-oxidant transcription factor. There are many Nrf2-interacting nutrients (berberine, curcumin, epigallocatechin gallate, genistein, quercetin, resveratrol, sulforaphane) that all act similarly to reduce insulin resistance, endothelial damage, lung injury and cytokine storm. They also act on the same mechanisms (mTOR: Mammalian target of rapamycin, PPAR gamma:Peroxisome proliferator-activated receptor, NF kappa B: Nuclear factor kappa B, ERK: Extracellular signal-regulated kinases and eIF2 alpha:Elongation initiation factor 2 alpha). They may as a result be important in mitigating the severity of COVID-19, acting through the endoplasmic reticulum stress or ACE-Angiotensin-II-AT(1)R axis (AT(1)R) pathway. Many Nrf2-interacting nutrients are also interacting with TRPA1 and/or TRPV1. Interestingly, geographical areas with very low COVID-19 mortality are those with the lowest prevalence of obesity (Sub-Saharan Africa and Asia). It is tempting to propose that Nrf2-interacting foods and nutrients can re-balance insulin resistance and have a significant effect on COVID-19 severity. It is therefore possible that the intake of these foods may restore an optimal natural balance for the Nrf2 pathway and may be of interest in the mitigation of COVID-19 severity
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