4,845 research outputs found
Cardioprotective and anti-hypertensive effects of Prosopis glandulosa in rat models of pre-diabetes
AIM: Obesity and type 2 diabetes present with two debilitating complications, namely, hypertension and heart disease. The dried and ground pods of Prosopis glandulosa (commonly known as the Honey mesquite tree) which is part of the Fabaceae (or legume) family are currently marketed in South Africa as a food supplement with blood glucose-stabilising and anti-hypertensive properties. We previously determined its hypoglycaemic effects, and in the current study we determined the efficacy of P glandulosa as anti-hypertensive agent and its myocardial protective ability.
METHODS: Male Wistar rats were rendered either pre-diabetic (diet-induced obesity: DIO) or hypertensive (high-fat diet: HFD). DIO animals were treated with P glandulosa (100 mg/kg/day for the last eight weeks of a 16-week period) and compared to age-matched controls. Hearts were perfused ex vivo to determine infarct size. Biometric parameters were determined at the time of sacrifice. Cardiac-specific insulin receptor knock-out (CIRKO) mice were similarly treated with P glandulosa and infarct size was determined. HFD animals were treated with P glandulosa from the onset of the diet or from weeks 12–16, using captopril (50 mg/kg/day) as the positive control. Blood pressure was monitored weekly. RESULTS: DIO rats and CIRKO mice: P glandulosa ingestion significantly reduced infarct size after ischaemia–reperfusion. Proteins of the PI-3-kinase/PKB/Akt survival pathway were affected in a manner supporting cardioprotection. HFD model: P glandulosa treatment both prevented and corrected the development of hypertension, which was also reflected in alleviation of water retention.
CONCLUSION: P glandulosa was cardioprotective and infarct sparing as well as anti-hypertensive without affecting the body weight or the intra-peritoneal fat depots of the animals. Changes in the PI-3-kinase/PKB/Akt pathway may be causal to protection. Results indicated water retention, possibly coupled to vasoconstriction in the HFD animals, while ingestion of P glandulosa alleviated both. We concluded that treatment of pre-diabetes, type 2 diabetes or hypertension with P glandulosa poses possible beneficial health effects.Department of HE and Training approved lis
A process-based life cycle sustainability assessment of the space-based solar power concept
For space-based solar power (SBSP) to be considered as a truly viable renewable energy technology, there should be a clear environmental benefit gained from its application. Additionally, given the scale of investment and engineering development, the price of energy must remain comparable to terrestrial-based generation systems for commercial feasibility. For this reason, a process-based life cycle sustainability assessment (LCSA) study was conducted to identify the life cycle environmental, economic and social impacts of the 1978 DOE/NASA Solar Power Satellite (SPS) Reference System. This was one of the first ever LCSA studies for space systems to be performed worldwide and was applied using a new LCSA tool for space missions developed at the University of Strathclyde. Taking a burden-based approach, the tool has been used to calculate environmental impacts across a wide range of different environmental impact categories and quantify costs over the system life cycle. The inclusion of social impacts adds additional depth to the analysis by showcasing the sociological impacts of the system on various stakeholder groups in line with the 2030 Agenda for Sustainable Development. The calculated life cycle impacts were then analysed further to identify potential hotspots through multi-criteria decision analysis (MCDA) and by measuring the results against annual global impacts (AGIs) and planetary boundaries (PBs). Life cycle CO2e emissions and costs were then compared to terrestrial energy generation systems in order to benchmark the relative performance of the technology as part of the conventional energy mix. The results suggest that whilst the DOE/NASA SPS Reference System can generally be described as a ‘green’ and ‘cost-effective’ system, several design improvements can and should be made to lessen its life cycle impacts. Therefore, it is proposed that the identified hotspots are used as a baseline for comparison or as mission drivers to continually improve future SPS designs
Simultaneous X-ray and Ultraviolet spectroscopy of the Seyfert galaxy NGC 5548. III. X-ray time variability
The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both
the HETGS and LETGS spectrometers. In this paper we study the time variability
of the continuum radiation. During our observation, the source showed a gradual
increase in flux over four days, followed by a rapid decrease and flattening of
the light curve afterwards. Superimposed upon these relatively slow variations
several short duration bursts or quasi-periodic oscillations occured with a
typical duration of several hours and separation between 0.6-0.9 days. The
bursts show a delay of the hard X-rays with respect to the soft X-rays of a few
hours. We interprete these bursts as due to a rotating, fluctuating hot spot at
approximately 10 gravitational radii; the time delay of the hard X-rays from
the bursts agree with the canonical picture of Inverse Compton scattering of
the soft accretion disk photons on a hot medium that is relatively close to the
central black hole.Comment: 6 pages, 7 figures, accepted for publication in Astronomy and
Astrophysic
Genes in the postgenomic era
We outline three very different concepts of the gene - 'instrumental', 'nominal', and 'postgenomic'. The instrumental gene has a critical role in the construction and interpretation of experiments in which the relationship between genotype and phenotype is explored via hybridization between organisms or directly between nucleic acid molecules. It also plays an important theoretical role in the foundations of disciplines such as quantitative genetics and population genetics. The nominal gene is a critical practical tool, allowing stable communication between bioscientists in a wide range of fields grounded in well-defined sequences of nucleotides, but this concept does not embody major theoretical insights into genome structure or function. The post-genomic gene embodies the continuing project of understanding how genome structure supports genome function, but with a deflationary picture of the gene as a structural unit. This final concept of the gene poses a significant challenge to conventional assumptions about the relationship between genome structure and function, and between genotype and phenotype
The Ionized Gas and Nuclear Environment in NGC 3783 V. Variability and Modeling of the Intrinsic Ultraviolet Absorption
We present results on the location, physical conditions, and geometry of the
outflow in the Seyfert 1 galaxy NGC 3783 from a study of the variable intrinsic
UV absorption. Based on 18 observations with HST/STIS and 6 observations with
FUSE, we find: 1) The absorption from the lowest-ionization species in each of
the three strong kinematic components varied inversely with the continuum flux,
indicating the ionization structure responded to changes in the photoionizing
flux over the weekly timescales sampled by our observations. 2) A multi-
component model with an unocculted NLR and separate BLR and continuum
line-of-sight covering factors predicts saturation in several lines, consistent
with the lack of observed variability. 3) Column densities for the individual
metastable levels are measured from the resolved C III *1175 absorption complex
observed in one component. Based on our computed metastable level populations,
the electron density of this absorber is ~3x10^4 cm^-3. Photoionization
modeling results place it at ~25 pc from the central source. 4) Using
time-dependent calculations, we are able to reproduce the detailed variability
observed in this absorber, and derive upper limits on the distances for the
other components of 25-50 pc. 5) The ionization parameters derived for the
higher ionization UV absorbers are consistent with the modeling results for the
lowest-ionization X-ray component, but with smaller total column density. They
have similar pressures as the three X-ray ionization components. These results
are consistent with an inhomogeneous wind model for the outflow in NGC 3783. 6)
Based on the predicted emission-line luminosities, global covering factor
constraints, and distances derived for the UV absorbers, they may be identified
with emission- line gas observed in the inner NLR of AGNs. (abridged)Comment: 30 pages, 18 figures (7 color), emulateapj, accepted for publication
in The Astrophysical Journa
A Spectroscopic and Photometric Study of Short-Timescale Variability in NGC5548
Results of a ground-based optical monitoring campaign on NGC5548 in June 1998
are presented. The broad-band fluxes (U,B,V), and the spectrophotometric
optical continuum flux F_lambda(5100 A) monotonically decreased in flux while
the broad-band R and I fluxes and the integrated emission-line fluxes of Halpha
and Hbeta remained constant to within 5%. On June 22, a short continuum flare
was detected in the broad band fluxes. It had an amplitude of about ~18% and it
lasted only ~90 min. The broad band fluxes and the optical continuum
F_lambda(5100 A) appear to vary simultaneously with the EUV variations. No
reliable delay was detected for the broad optical emission lines in response to
the EUVE variations. Narrow Hbeta emission features predicted as a signature of
an accretion disk were not detected during this campaign. However, there is
marginal evidence for a faint feature at lambda = 4962 A with FWHM=~6 A
redshifted by Delta v = 1100 km/s with respect to Hbeta_narrow.Comment: 12 pages, 7 figures, accepted for publishing in A&
From life cycle assessment of space systems to environmental communication and reporting
Within the European space sector, heightened interest in Life Cycle Assessment (LCA) has been stimulated by an increased motivation and urgency on quantifying environmental consequences of space activities. The associated growth in the application of this method places a greater emphasis on obtaining high levels of transparency, reliability and validity of all ensuing environmental claims. As such, the purpose of this study is to present a potential pathway for effective space-specific environmental communication and reporting. The paper outlines the results of a scoping exercise designed to map the specificities of the space sector against the ISO 14025:2006 standard on environmental labels and declarations. This was based on a literature review conducted to obtain the current state of knowledge within the space industry whilst drawing upon the procedures and experiences of other sectors, with particular consideration to Product Environmental Footprint Category Rule (PEFCR) development. The findings from this activity have been used to formulate a harmonised framework for environmental communication and reporting purposes in the context of the European space sector. The framework provides a comprehensive set of voluntary operating procedures which intend to act as preliminary guidance for European industrial stakeholders and national agencies. The paper goes on to discuss potential future framework refinements and provides a list of recommendations to advance sectoral practices further. This includes a call for the establishment of an industry specific platform to enhance the harmonisation of LCA development and ensure rigorous verification and validation of environmental claims
Mass Calibration and Cosmological Analysis of the SPT-SZ Galaxy Cluster Sample Using Velocity Dispersion and X-ray Measurements
We present a velocity dispersion-based mass calibration of the South Pole
Telescope Sunyaev-Zel'dovich effect survey (SPT-SZ) galaxy cluster sample.
Using a homogeneously selected sample of 100 cluster candidates from 720 deg2
of the survey along with 63 velocity dispersion () and 16 X-ray Yx
measurements of sample clusters, we simultaneously calibrate the
mass-observable relation and constrain cosmological parameters. The
calibrations using and Yx are consistent at the level,
with the calibration preferring ~16% higher masses. We use the full
cluster dataset to measure . The
SPT cluster abundance is lower than preferred by either the WMAP9 or
Planck+WMAP9 polarization (WP) data, but assuming the sum of the neutrino
masses is eV, we find the datasets to be consistent at the
1.0 level for WMAP9 and 1.5 for Planck+WP. Allowing for larger
further reconciles the results. When we combine the cluster and
Planck+WP datasets with BAO and SNIa, the preferred cluster masses are
higher than the Yx calibration and higher than the
calibration. Given the scale of these shifts (~44% and ~23% in mass,
respectively), we execute a goodness of fit test; it reveals no tension,
indicating that the best-fit model provides an adequate description of the
data. Using the multi-probe dataset, we measure and
. Within a CDM model we find eV. We present a consistency test of the cosmic growth rate.
Allowing both the growth index and the dark energy equation of state
parameter to vary, we find and ,
demonstrating that the expansion and the growth histories are consistent with a
LCDM model ().Comment: Accepted by ApJ (v2 is accepted version); 17 pages, 6 figure
Analysis of Sunyaev-Zel'dovich Effect Mass-Observable Relations using South Pole Telescope Observations of an X-ray Selected Sample of Low Mass Galaxy Clusters and Groups
(Abridged) We use 95, 150, and 220GHz observations from the SPT to examine
the SZE signatures of a sample of 46 X-ray selected groups and clusters drawn
from ~6 deg^2 of the XMM-BCS. These systems extend to redshift z=1.02, have
characteristic masses ~3x lower than clusters detected directly in the SPT data
and probe the SZE signal to the lowest X-ray luminosities (>10^42 erg s^-1)
yet.
We develop an analysis tool that combines the SZE information for the full
ensemble of X-ray-selected clusters. Using X-ray luminosity as a mass proxy, we
extract selection-bias corrected constraints on the SZE significance- and
Y_500-mass relations. The SZE significance- mass relation is in good agreement
with an extrapolation of the relation obtained from high mass clusters.
However, the fit to the Y_500-mass relation at low masses, while in good
agreement with the extrapolation from high mass SPT clusters, is in tension at
2.8 sigma with the constraints from the Planck sample. We examine the tension
with the Planck relation, discussing sample differences and biases that could
contribute.
We also present an analysis of the radio galaxy point source population in
this ensemble of X-ray selected systems. We find 18 of our systems have 843 MHz
SUMSS sources within 2 arcmin of the X-ray centre, and three of these are also
detected at significance >4 by SPT. Of these three, two are associated with the
group brightest cluster galaxies, and the third is likely an unassociated
quasar candidate. We examine the impact of these point sources on our SZE
scaling relation analyses and find no evidence of biases. We also examine the
impact of dusty galaxies using constraints from the 220 GHz data. The stacked
sample provides 2.8 significant evidence of dusty galaxy flux, which
would correspond to an average underestimate of the SPT Y_500 signal that is
(17+-9) per cent in this sample of low mass systems.Comment: 15 pages, 7 figure
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