247 research outputs found
Development of a Method for the Fast and Complete Assessment of Quality Characteristics in Undried Grass Silages by Means of an NIR-Diode Array Spectrometer
Traditionally, the determination of grass silage is very time consuming and needs a lot of manpower and chemicals. The advantages of conventional laboratory NIRS instruments are well known but their disadvantage lies in their lacking suitability for on-farm use. A new type of spectrometer based on diode arrays may be used for this purpose. However, these new instruments still need to be calibrated for an accurate estimate of the fermentative and nutritive value of wet and unchopped grass silage
A comprehensive analysis of the hard X-ray spectra of bright Seyfert galaxies
Hard X-ray spectra of 28 bright Seyfert galaxies observed with INTEGRAL were
analyzed together with the X-ray spectra from XMM-Newton, Suzaku and RXTE.
These broad-band data were fitted with a model assuming a thermal
Comptonization as a primary continuum component. We tested several model
options through a fitting of the Comptonized continuum accompanied by a complex
absorption and a Compton reflection. Both the large data set used and the model
space explored allowed us to accurately determine a mean temperature kTe of the
electron plasma, the Compton parameter y and the Compton reflection strength R
for the majority of objects in the sample. Our main finding is that a vast
majority of the sample (20 objects) is characterized by kTe < 100 keV, and only
for two objects we found kTe > 200 keV. The median kTe for entire sample is
48(-14,+57) keV. The distribution of the y parameter is bimodal, with a broad
component centered at ~0.8 and a narrow peak at ~1.1. A complex, dual absorber
model improved the fit for all data sets, compared to a simple absorption
model, reducing the fitted strength of Compton reflection by a factor of about
2. Modest reflection (median R ~0.32) together with a high ratio of Comptonized
to seed photon fluxes point towards a geometry with a compact hard X-ray
emitting region well separated from the accretion disc. Our results imply that
the template Seyferts spectra used in AGN population synthesis models should be
revised.Comment: 26 pages, 12 figures, accepted for publication in MNRA
Differential Dynamic Microscopy to characterize Brownian motion and bacteria motility
We have developed a lab work module where we teach undergraduate students how
to quantify the dynamics of a suspension of microscopic particles, measuring
and analyzing the motion of those particles at the individual level or as a
group. Differential Dynamic Microscopy (DDM) is a relatively recent technique
that precisely does that and constitutes an alternative method to more
classical techniques such as dynamics light scattering (DLS) or video particle
tracking (VPT). DDM consists in imaging a particle dispersion with a standard
light microscope and a camera. The image analysis requires the students to code
and relies on digital Fourier transform to obtain the intermediate scattering
function, an autocorrelation function that characterizes the dynamics of the
dispersion. We first illustrate DDM on the textbook case of colloids where we
measure the diffusion coefficient. Then we show that DDM is a pertinent tool to
characterize biologic systems such as motile bacteria i.e.bacteria that can
self propel, where we not only determine the diffusion coefficient but also the
velocity and the fraction of motile bacteria. Finally, so that our paper can be
used as a tutorial to the DDM technique, we have joined to this article movies
of the colloidal and bacterial suspensions and the DDM algorithm in both Matlab
and Python to analyze the movies
IGRJ17361-4441: a possible new accreting X-ray binary in NGC6388
IGRJ17361-4441 is a newly discovered INTEGRAL hard X-ray transient, located
in the globular cluster NGC6388. We report here the results of the X-ray and
radio observations performed with Swift, INTEGRAL, RXTE, and the Australia
Telescope Compact Array (ATCA) after the discovery of the source on 2011 August
11. In the X-ray domain, IGRJ17361-4441 showed virtually constant flux and
spectral parameters up to 18 days from the onset of the outburst. The
broad-band (0.5-100 keV) spectrum of the source could be reasonably well
described by using an absorbed power-law component with a high energy cut-off
(N_H\simeq0.8x10^(22) cm^(-2), {\Gamma}\simeq0.7-1.0, and E_cut\simeq25 keV)
and displayed some evidence of a soft component below \sim2 keV. No coherent
timing features were found in the RXTE data. The ATCA observation did not
detect significant radio emission from IGRJ17361-4441, and provided the most
stringent upper limit (rms 14.1 {\mu}Jy at 5.5 GHz) to date on the presence of
any radio source close to the NGC6388 center of gravity. The improved position
of IGRJ17361-4441 in outburst determined from a recent target of opportunity
observation with Chandra, together with the X-ray flux and radio upper limits
measured in the direction of the source, argue against its association with the
putative intermediate-mass black hole residing in the globular cluster and with
the general hypothesis that the INTEGRAL source is a black hole candidate.
IGRJ17361-4441 might be more likely a new X-ray binary hosting an accreting
neutron star. The ATCA radio non-detection also permits us to derive an upper
limit to the mass of the suspected intermediate massive black hole in NGC6388
of <600 M\odot. This is a factor of 2.5 lower than the limit reported
previously.Comment: Accepted for publication on A&A lette
Implementation of Triple P-Positive Parenting Program in Hong Kong: Predictors of programme completion and clinical outcomes
This study examined the effectiveness of the Triple P-Positive Parenting Program in a government child health service delivery context with Chinese parents in Hong Kong. Specifically, the study sought to identify pre-intervention variables that might predict programme outcomes such as, level of clinical improvement and programme completion. Participants were 661 parents of pre-school and primary aged children participating in a group version of the Triple P-Positive Parenting Program. There were significant decreases in disruptive child behaviours, levels of parenting stress, general stress and anxiety and an increase in parenting sense of competence. Greater change in reports of child behaviour problems was related to lower levels of family income, new immigrant family status, and higher pre-intervention levels of parenting stress. The present study provides a profile of parents who are most likely to benefit from parent training programmes
A Hybrid System Using Symbolic and Numeric Knowledge for the Semantic Annotation of Sulco-Gyral Anatomy in Brain MRI Images
Melarsoprol cyclodextrin inclusion complexes as promising oral candidates for the treatment of human African trypanosomiasis
Human African trypanosomiasis (HAT), or sleeping sickness, results from infection with the protozoan parasites <i>Trypanosoma brucei</i> (<i>T.b.</i>) <i>gambiense</i> or <i>T.b.rhodesiense</i> and is invariably fatal if untreated. There are 60 million people at risk from the disease throughout sub-Saharan Africa. The infection progresses from the haemolymphatic stage where parasites invade the blood, lymphatics and peripheral organs, to the late encephalitic stage where they enter the central nervous system (CNS) to cause serious neurological disease. The trivalent arsenical drug melarsoprol (Arsobal) is the only currently available treatment for CNS-stage <i>T.b.rhodesiense</i> infection. However, it must be administered intravenously due to the presence of propylene glycol solvent and is associated with numerous adverse reactions. A severe post-treatment reactive encephalopathy occurs in about 10% of treated patients, half of whom die. Thus melarsoprol kills 5% of all patients receiving it. Cyclodextrins have been used to improve the solubility and reduce the toxicity of a wide variety of drugs. We therefore investigated two melarsoprol cyclodextrin inclusion complexes; melarsoprol hydroxypropyl-͎-cyclodextrin and melarsoprol randomly-methylated-β-cyclodextrin. We found that these compounds retain trypanocidal properties <i>in vitro</i> and cure CNS-stage murine infections when delivered orally, once per day for 7-days, at a dosage of 0.05 mmol/kg. No overt signs of toxicity were detected. Parasite load within the brain was rapidly reduced following treatment onset and magnetic resonance imaging showed restoration of normal blood-brain barrier integrity on completion of chemotherapy. These findings strongly suggest that complexed melarsoprol could be employed as an oral treatment for CNS-stage HAT, delivering considerable improvements over current parenteral chemotherapy
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