3,120 research outputs found
Study of a Strategy for Parallax Microlensing Detection Towards the Magellanic Clouds
In this article, we have investigated the possibility to distinguish between
different galactic models through the microlensing parallax studies. We show
that a systematic search for parallax effects can be done using the currently
running alert systems and complementary photometric telescopes, to distinguish
between different lens distance distributions. We have considered two galactic
dark compact objects distributions, with total optical depths corresponding to
the EROS current upper limits. These models correspond to two extreme
hypothesis on a three component galactic structure made of a thin disc, a thick
disc, and a spherically symmetric halo. Our study shows that for sub-solar mass
lenses, an exposure of staryr toward LMC should allow to
distinguish between these two extreme models. In addition the self-lensing
hypothesis (lensing by LMC objects) can efficiently be tested through the
method proposed here.Comment: 10 pages, 12 eps figures. To be published in A&A (accepted version).
Minor changes: - Discussion added on the differential velocity of the thick
galactic disk with respect to the thin disk. - Quality and lisibility of
figures improved. - Typo errors correcte
Reliability assessment of microgrid with renewable generation and prioritized loads
With the increase in awareness about the climate change, there has been a
tremendous shift towards utilizing renewable energy sources (RES). In this
regard, smart grid technologies have been presented to facilitate higher
penetration of RES. Microgrids are the key components of the smart grids.
Microgrids allow integration of various distributed energy resources (DER) such
as the distributed generation (DGs) and energy storage systems (ESSs) into the
distribution system and hence remove or delay the need for distribution
expansion. One of the crucial requirements for utilities is to ensure that the
system reliability is maintained with the inclusion of microgrid topology.
Therefore, this paper evaluates the reliability of a microgrid containing
prioritized loads and distributed RES through a hybrid analytical-simulation
method. The stochasticity of RES introduces complexity to the reliability
evaluation. The method takes into account the variability of RES through Monte-
Carlo state sampling simulation. The results indicate the reliability
enhancement of the overall system in the presence of the microgrid topology. In
particular, the highest priority load has the largest improvement in the
reliability indices. Furthermore, sensitivity analysis is performed to
understand the effects of the failure of microgrid islanding in the case of a
fault in the upstream network
Osmo and hydro priming improvement germination characteristics and enzyme activity of Mountain Rye (Secale montanum) seeds under drought stress
Impacts of various concentrations of polyetylenglycol 6000 (PEG 6000)(0, -9, -11, -13 and -15 bar) and hydro priming on Mountain Rye (secale montanum) germination characteristic and enzyme activity were evaluated under drought stress in the seed laboratory of Natural Resources Faculty, University of Tehran, Karaj, Iran. Analyze of variance for hydro priming showed that temperature × time of priming interaction was significantly for germination percentage (GP), normal seedling percentage (NSP), coefficient of velocity of germination (CVG), seedling vigor index (SVI), coefficient of allometry (AC) and seedling length (SL) under drought stress and for osmo priming showed that Concentration of PEG × Temperature × Time of priming interaction was significantly for all traits under drought stress. Results of interaction effects for hydro priming showed that the highest GP (53%) and NSP (23.5%) were attained from hydro priming for 16h at 15 ◦C and the highest CVG (0.21) and AC (0.49) were attained from hydro priming for 8h at 10 ◦C, also hydro priming for 8h at 15 ◦C increased SL (3.15) as compared to the unprimed.Osmo priming with concentration of -15 bar PEG for 24h at 15 ◦C increased GP (80.5 %), GI (17.9), NSP (45 %), SVI (257.85) and SL (5.73 cm) and decreased MTG as compared to the unprimed and other treatments of osmo priming. The highest CVG was attained from concentration of -9 bar PEG for 24h at 10 ◦C. the highest AC was attained from concentration of -9 bar PEG for 12h at 15 ◦C. Also osmo and hydro priming increased catalase (CAT) and ascorbate peroxidase (APX) as compared to the unprimed
About the connection between the power spectrum of the Cosmic Microwave Background and the Fourier spectrum of rings on the sky
In this article we present and study a scaling law of the CMB
Fourier spectrum on rings which allows us (i) to combine spectra corresponding
to different colatitude angles (e.g. several detectors at the focal plane of a
telescope), and (ii) to recover the power spectrum once the
coefficients have been measured. This recovery is performed numerically below
the 1% level for colatitudes degrees. In addition, taking
advantage of the smoothness of the and of the , we provide
analytical expressions which allow to recover one of the spectrum at the 1%
level, the other one being known.Comment: 8 pages, 8 figure
The prevalence of domestic violence among pregnant women in Nigeria: a systematic review.
To identify, appraise, and synthesize research evidence on the prevalence of domestic violence (DV) among pregnant women in Nigeria. We conducted a systematic review of all published studies between April 2004 and June 2016. Comprehensive searches were conducted on electronic databases such as PubMed, CINAHL, Global Health, MEDLINE, PsycINFO, Directory of Open Access Journals, Google Scholar, and electronic libraries of the authors' institution. Identified articles were screened in two stages against the inclusion criteria with titles and abstract screened first followed by full-text screening. Selected articles were assessed using the "guidelines for evaluating prevalence studies," and findings were synthesized narratively. Among 19 studies that met the inclusion criteria, two articles were excluded due to low methodological quality and 17 articles were included in the review. The prevalence of DV during pregnancy in Nigeria ranged between 2.3% and 44.6% with lifetime prevalence rates ranging between 33.1% and 63.2%. Physical, sexual, psychological, and verbal abuses were the most frequent types of DV reported in this review. The most common perpetrators were husbands, as reported in 11 of the 17 studies. Pregnant women between the ages of 20 and 30 years were the most common victims of DV. Our review suggests high prevalence of DV in pregnancy among women in Nigeria and higher lifetime prevalence. However, determining an overall, synthesized accurate prevalence rate of DV within this population based on existing evidence presents a challenge. The findings have important implications for stakeholders such as planners, policy makers, maternity care providers, and researchers in public health and social policy at national, regional, and international levels toward combating the issue. OBJECTIVE METHOD RESULTS CONCLUSIO
Predicting seed germination of safflower (Carthamus tinctorius) cultivars using hydrotime model
Safflower (Carthamus
tinctorius) is a highly branched, herbaceous,
thistle-like annual plant. It is commercially
cultivated for vegetable oil extracted from
the seeds, which is cultivated under arid
environments. In such environments, the
water needed for germination is available
for only a short time and, consequently,
successful crop establishment depends not
only on rapid and uniform germination of
the seedlot, but also on its ability to
germinate under low water availability. All
of these attributes can be analyzed through
the hydrotime model (HT). Safflower seeds
were germinated in various polyethylene
glycol (PEG 600) solutions to obtain water
potentials of 0, -0.2, -0.4, -0.6, and -0.8
Mpa. Results indicated that germination of
safflower cultivars decreased significantly
with reduction of osmotic potential. The
highest germination percentage for Sina
(93.06 and 94.02%), Faraman (93.52 and
95.33%), Talaei (94.98 and 93.98%) and
Kouseh (93.58 and 95.55%) cultivars were
attained from distilled water (0 MPa) and
-0.2 MPa, respectively. The hydrotime
constant (θH) for Sina, Faraman, Talaei and
Kouseh cultivars were 0.93, 0.84, 0.78 and
0.72 MPa d, and the water potential (Ψb(50))
for Sina, Faraman, Talaei and Kouseh
cultivars were -0.56, -0.67, -0.64 and -0.77
MPa, respectively. Cumulative germination
of safflower seed was higher in Kouseh
cultivar, than in Sina, Faraman and Talaei
cultivars. Results showed that, hydrotime
model is suited to predicting seed
germination of safflower seeds. In addition,
the information gathered with this work
allows us to build mathematical models to
predict germination of safflower cultivars in
the field under various environments
The effect of priming on germination characteristics of barley seeds under drought stress conditions
Seed priming methods have been used to increase germination and seedling establishment under different abiotic stress conditions. Seed priming was used in barley to increase seed germination and tolerance on stress exposure. Barley seeds were treated with various priming agents for different time and temperatures. The effect of priming
was assessed on germination characteristics on subsequent exposure to drought
(PEG-12 bar) stress for 7 days. Seed priming treatments significantly (p≤ 0.01)
affected germination percentage (GP), normality seedling percentage (NSP), germination Index (GI), germination uniformity (GU), means time to germination (MTG), coefficient of
velocity of germination (CVG), seedling vigor index (SVI) and coefficient of allometry (AC). Seed priming with gibberelic acid (GA), salicylic acid (SA), ascorbic acid (ASc), hydropriming (HP), osmopriming (OP) and combined treatments (CT) significantly (p≤ 0.01) increased germination characteristics, compared to the unprimed. Seed priming
with concentrations 25, 50 ppm of GA for 15 h at 10°C, 25 ppm of SA for 12 h at 10°C, 50 ppm of ASc for 12 h at 15°C, treatment 16 h hydropriming at 10°C and -15 bar PEG for 24 h for osmopriming maybe considered as optimal treatment for priming of barley seeds in drought stress conditions. In some cases, combined treatments are better than the
separate treatments. Seed priming with PEG (potential -l5 bar PEG for 24 h at 10°C) was more effective in drought stress than the other treatments
A systematic review of Hepatitis B virus (HBV) prevalence and genotypes in Kenya: Data to inform clinical care and health policy
The aim of this systematic review and meta-analysis is to evaluate available prevalence and viral sequencing data representing chronic hepatitis B (CHB) infection in Kenya. More than 20% of the global disease burden from CHB is in Africa, however there is minimal high quality seroprevalence data from individual countries and little viral sequencing data available to represent the continent. We undertook a systematic review of the prevalence and genetic data available for hepatitis B virus (HBV) in Kenya using the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) 2020 checklist. We identified 23 studies reporting HBV prevalence and 8 studies that included HBV genetic data published in English between January 2000 and December 2021. We assessed study quality using the Joanna Briggs Institute critical appraisal checklist. Due to study heterogeneity, we divided the studies to represent low, moderate, high and very high-risk for HBV infection, identifying 8, 7, 5 and 3 studies in these groups, respectively. We calculated pooled HBV prevalence within each group and evaluated available sequencing data. Pooled HBV prevalence was 3.4% (95% CI 2.7–4.2%), 6.1% (95% CI 5.1–7.4%), 6.2% (95% CI 4.64–8.2) and 29.2% (95% CI 12.2–55.1), respectively. Study quality was overall low; only three studies detailed sample size calculation and 17/23 studies were cross sectional. Eight studies included genetic information on HBV, with two undertaking whole genome sequencing. Genotype A accounted for 92% of infections. Other genotypes included genotype D (6%), D/E recombinants (1%) or mixed populations (1%). Drug resistance mutations were reported by two studies. There is an urgent need for more high quality seroprevalence and genetic data to represent HBV in Kenya to underpin improved HBV screening, treatment and prevention in order to support progress towards elimination targets
A systematic review of Hepatitis B virus (HBV) prevalence and genotypes in Kenya: data to inform clinical care and health policy
The aim of this systematic review and meta-analysis is to evaluate available prevalence and viral sequencing data representing chronic hepatitis B (CHB) infection in Kenya. More than 20% of the global disease burden from CHB is in Africa, however there is minimal high quality seroprevalence data from individual countries and little viral sequencing data available to represent the continent. We undertook a systematic review of the prevalence and genetic data available for hepatitis B virus (HBV) in Kenya using the Preferred Reporting Items for Systematic Review and Meta-analysis (PRISMA) 2020 checklist. We identified 23 studies reporting HBV prevalence and 8 studies that included HBV genetic data published in English between January 2000 and December 2021. We assessed study quality using the Joanna Briggs Institute critical appraisal checklist. Due to study heterogeneity, we divided the studies to represent low, moderate, high and very high-risk for HBV infection, identifying 8, 7, 5 and 3 studies in these groups, respectively. We calculated pooled HBV prevalence within each group and evaluated available sequencing data. Pooled HBV prevalence was 3.4% (95% CI 2.7-4.2%), 6.1% (95% CI 5.1-7.4%), 6.2% (95% CI 4.64-8.2) and 29.2% (95% CI 12.2-55.1), respectively. Study quality was overall low; only three studies detailed sample size calculation and 17/23 studies were cross sectional. Eight studies included genetic information on HBV, with two undertaking whole genome sequencing. Genotype A accounted for 92% of infections. Other genotypes included genotype D (6%), D/E recombinants (1%) or mixed populations (1%). Drug resistance mutations were reported by two studies. There is an urgent need for more high quality seroprevalence and genetic data to represent HBV in Kenya to underpin improved HBV screening, treatment and prevention in order to support progress towards elimination targets
- …