574 research outputs found
Migration of Ca II H bright points in the internetwork
The migration of magnetic bright point-like features (MBP) in the lower solar
atmosphere reflects the dispersal of magnetic flux as well as the horizontal
flows of the atmospheric layer they are embedded in. We analyse trajectories of
the proper motion of intrinsically magnetic, isolated internetwork Ca II H MBPs
(mean lifetime 461 +- 9 s) to obtain their diffusivity behaviour. We use
seeing-free high spatial and temporal resolution image sequences of quiet-Sun,
disc-centre observations obtained in the Ca II H 3968 {\AA} passband of the
Sunrise Filter Imager (SuFI) onboard the Sunrise balloon-borne solar
observatory. Small MBPs in the internetwork are automatically tracked. The
trajectory of each MBP is then calculated and described by a diffusion index
({\gamma}) and a diffusion coefficient (D). We further explore the distribution
of the diffusion indices with the help of a Monte Carlo simulation. We find
{\gamma} = 1.69 +- 0.08 and D = 257 +- 32 km^2/s averaged over all MBPs.
Trajectories of most MBPs are classified as super-diffusive, i.e., {\gamma} >
1, with the determined {\gamma} being to our knowledge the largest obtained so
far. A direct correlation between D and time-scale ({\tau}) determined from
trajectories of all MBPs is also obtained. We discuss a simple scenario to
explain the diffusivity of the observed, relatively short-lived MBPs while they
migrate within a small area in a supergranule (i.e., an internetwork area). We
show that the scatter in the {\gamma} values obtained for individual MBPs is
due to their limited lifetimes. The super-diffusive MBPs can be well-described
as random walkers (due to granular evolution and intergranular turbu- lence)
superposed on a large systematic (background) velocity, caused by granular,
mesogranular and supergranular flows.Comment: 10 pages, 7 figures, 3 table
Inclinations of small quiet-Sun magnetic features based on a new geometric approach
High levels of horizontal magnetic flux have been reported in the quiet-Sun
internetwork, often based on Stokes profile inversions. Here we introduce a new
method for deducing the inclination of magnetic elements and use it to test
magnetic field inclinations from inversions. We determine accurate positions of
a set of small, bright magnetic elements in high spatial resolution images
sampling different photospheric heights obtained by the Sunrise balloon-borne
solar observatory. Together with estimates of the formation heights of the
employed spectral bands, these provide us with the inclinations of the magnetic
features. We also compute the magnetic inclination angle of the same magnetic
features from the inversion of simultaneously recorded Stokes parameters. Our
new, geometric method returns nearly vertical fields (average inclination of
around 14 deg with a relatively narrow distribution having a standard deviation
of 6 deg). In strong contrast to this, the traditionally used inversions give
almost horizontal fields (average inclination of 75+-8 deg) for the same small
magnetic features, whose linearly polarised Stokes profiles are adversely
affected by noise. The almost vertical field of bright magnetic features from
our geometric method is clearly incompatible with the nearly horizontal
magnetic fields obtained from the inversions. This indicates that the amount of
magnetic flux in horizontal fields deduced from inversions is overestimated in
the presence of weak Stokes signals, in particular if Stokes Q and U are close
to or under the noise level. By combining the proposed method with inversions
we are not just improving the inclination, but also the field strength. This
technique allows us to analyse features that are not reliably treated by
inversions, thus greatly extending our capability to study the complete
magnetic field of the quiet Sun.Comment: 12 pages, 9 figures, 1 table; Accepted for publication in Astronomy &
Astrophysic
A novel method to design variable gain amplifier
A novel method to design of Variable gain Amplifiers (VGAs) is proposed. A low power VGA with wide range of gain variation and appropriate bandwidth using new technique is presented in this paper. Moreover, the suggested circuit is simulated in whole process corners and different temperatures in the region of -50 to +70 ºC. The circuit has been designed in a typical 0.35μm CMOS process with a power supply of 3.3V, and simulated by HSPICE software using level 49 parameters (BSIM3v3).Keywords: variable gain amplifier; Operational Transconductance Amplifier; wide gain range; low power; unity gain bandwidt
Search Engine Advertising Adoption and Utilization: An Empirical Investigation of Inflectional Factors
© Taylor & Francis Group, LLC. Search engine advertising (SEA) is a prominent source of revenue for search engine companies, and also a solution for businesses to promote their visibility on the web. However, there is little academic research available about the factors and the extent to which they may influence businesses’ decision to adopt SEA. Building on Theory of Planned Behavior, Technology Acceptance Model, and Unified Theory of Acceptance and Use of Technology, this study develops a context-specific model for understanding the factors that influence the decision of businesses to use SEA. Using structural equation modeling and survey data collected from 142 businesses, this research finds that the intention of businesses to use SEA is directly influenced by four factors: (i) attitude toward SEA, (ii) subjective norms, (iii) perceived control over SEA, and (iv) perceived benefits of SEA in terms of increasing web traffic, increasing sales and creating awareness. Furthermore, the research we discover six additional factors that have an indirect influence: (i) trust in search engines, (ii) perceived risk of SEA, (iii) ability to manage keywords and bids, (iv) ability to analyze and monitor outcomes, (v) advertising expertise, and (vi) using external experts
Synthesis of silica nanoparticles by modified sol–gel process: the effect of mixing modes of the reactants and drying techniques
A modified preparation of silica nanoparticles via sol–gel process was described. The ability to control the particle size and distribution was found highly dependent on mixing modes of the reactants and drying techniques. The mixture of tetraethoxysilane and ethanol followed by addition of water (Mode-A) produced monodispersed powder with an average particle size of 10.6 ± 1.40 nm with a narrow size distribution. The freeze drying technique (FD) further improved the quality of powder. In addition, the freeze dried samples have shown unique TGA decomposition steps which might be related to the well-defined structure of silica nanoparticles as compared to the heat dried samples. DSC analysis showed that FD preserved the silica surface with low shrinkage and generated remarkably well-order, narrow and bigger pore size and pore volume and also large endothermic enthalpies (ΔH FD = −688 J g−1 vs. ΔH HD = −617 J g−1) that lead to easy escape of physically adsorbed water from the pore at lower temperature
Effective antibiotic conservation by emergency antimicrobial stewardship during a drug shortage
We present the first description of an antimicrobial stewardship program (ASP) used to successfully manage a multi-antimicrobial drug shortage. Without resorting to formulary restriction, meropenem utilization decreased by 69% and piperacillin-tazobactam by 73%. During the shortage period, hospital mortality decreased (P=.03), while hospital length of stay remained unchanged.Infect Control Hosp Epidemiol 2017;38:356–359</jats:p
Improving Female Health at Various Life Stages: A systematic review of date fruit products' impact
This systematic review study aimed to investigate the impact of date fruit products on female health at different stages of their lives. The quality of the included studies was evaluated using the risk of bias(RoB) assessment tool. After reviewing 21 eligible studies concluded that, date fruits have a beneficial impact on puberty, reproduction, and menopause periods. During puberty, the consumption of date fruits improved hemoglobin levels in adolescent girls. In reproductive age, date fruits have positive effects on fertility parameters and the sexual function of women and men. Furthermore, in the menopausal period, date fruits improve dyspareunia and help to maintain better ovarian reserves. Supporting women with proper nutrition and enhancing their diet can lead to cost savings compared to medical interventions, and is considered a key preventive measure for improving women's health. By offering simple advice, women can enhance their quality of life and better cope with life's challenges
Kinematics and Magnetic Properties of a Light Bridge in a Decaying Sunspot
We present the results obtained by analyzing high spatial and spectral
resolution data of the solar photosphere acquired by the CRisp Imaging
SpectroPolarimeter at the Swedish Solar Telescope on 6 August 2011, relevant to
a large sunspot with a light bridge (LB) observed in NOAA AR 11263. These data
are complemented by simultaneous Hinode Spectropolarimeter (SP) observation in
the Fe I 630.15 nm and 630.25 nm lines. The continuum intensity map shows a
discontinuity of the radial distribution of the penumbral filaments in
correspondence with the LB, which shows a dark lane (about 0.3" wide and about
8.0" long) along its main axis. The available data were inverted with the
Stokes Inversion based on Response functions (SIR) code and physical parameters
maps were obtained. The line-of-sight (LOS) velocity of the plasma along the LB
derived from the Doppler effect shows motions towards and away from the
observer up to 0.6 km/s, which are lower in value than the LOS velocities
observed in the neighbouring penumbral filaments. The noteworthy result is that
we find motions toward the observer up to 0.6 km/s in the dark lane where the
LB is located between two umbral cores, while the LOS velocity motion toward
the observer is strongly reduced where the LB is located between an umbral core
at one side and penumbral filaments on the other side. Statistically, the LOS
velocities correspond to upflows/downflows andcomparing these results with
Hinode/SP data, we conclude that the surrounding magnetic field configuration
(whether more or less inclined) could have a role in maintaining the conditions
for the process of plasma piling up along the dark lane. The results obtained
from our study support and confirm outcomes of recent magnetohydro-dynamic
simulations showing upflows along the main axis of a LBs
Determination of suitable areas for reforestation and afforestation with indigenous species
To be successful in tree establishment, an assessment of land suitability would be necessary. The aim of this study
was determining the potential habitats of three native tree species (Quercus persica, Pistacia atlantica, Amygdalous
scoparia) in Siahkoh region of Ilam County, using Boolean method and Geographic Information Systems (GIS). For
this regard, the slope, aspect and hypsometric maps of the area were produced using topographic maps. To provide
soil properties maps, 40 soil samples in depth of 30 cm were randomly taken from the defined region (about 954
ha). Soil sample properties such as pH, texture, electrical conductivity, and organic material were measured. Soil
maps and soil data layers were produced in GIS environment. With respect to ecological needs of the selected tree
species and combining of all provided maps, about 890 ha of the total area could be reforested or afforested. The
results show that from the total suitable area, 368.72 ha (41.41 %) for Quercus persica, 353.44 ha (36.69 %) for Pistacia
atlantica and 176.2 ha (19.78 %) for Amygdalus scoparia were found to be suitable for these species. The results of
comparing the extracted suitability map with the existing 30 ha afforestation in the region show that, from 10
hectares afforested by each species, Quercus persica, Pistacia atlantica and Amygdalus scoparia 7.65, 3.11 and 4.25 ha
are located in the high suitable areas, respectively
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