2,903 research outputs found
Preliminary study of kaonic deuterium X-rays by the SIDDHARTA experiment at DAFNE
The study of the KbarN system at very low energies plays a key role for the
understanding of the strong interaction between hadrons in the strangeness
sector. At the DAFNE electron-positron collider of Laboratori Nazionali di
Frascati we studied kaonic atoms with Z=1 and Z=2, taking advantage of the
low-energy charged kaons from Phi-mesons decaying nearly at rest. The SIDDHARTA
experiment used X-ray spectroscopy of the kaonic atoms to determine the
transition yields and the strong interaction induced shift and width of the
lowest experimentally accessible level (1s for H and D and 2p for He). Shift
and width are connected to the real and imaginary part of the scattering
length. To disentangle the isospin dependent scattering lengths of the
antikaon-nucleon interaction, measurements of Kp and of Kd are needed. We
report here on an exploratory deuterium measurement, from which a limit for the
yield of the K-series transitions was derived: Y(K_tot)<0.0143 and
Y(K_alpha)<0.0039 (CL 90%). Also, the upcoming SIDDHARTA-2 kaonic deuterium
experiment is introduced.Comment: Accepted by Nuclear Physics
X-ray transition yields of low-Z kaonic atoms produced in Kapton
The X-ray transition yields of kaonic atoms produced in Kapton polyimide
(C22H10N2O5) were measured for the first time in the SIDDHARTA experiment.
X-ray yields of the kaonic atoms with low atomic numbers (Z = 6, 7, and 8) and
transitions with high principal quantum numbers (n = 5-8) were determined. The
relative yield ratios of the successive transitions and those of
carbon-to-nitrogen (C:N) and carbon-to-oxygen (C:O) were also determined. These
X-ray yields provide important information for understanding the capture ratios
and cascade mechanisms of kaonic atoms produced in a compound material, such as
Kapton.Comment: Accepted in Nucl. Phys. A (2013
First measurement of kaonic helium-3 X-rays
The first observation of the kaonic 3He 3d - 2p transition was made using
slow K- mesons stopped in a gaseous 3He target. The kaonic atom X-rays were
detected with large-area silicon drift detectors using the timing information
of the K+K- pairs of phi-meson decays produced by the DAFNE e+e- collider. The
strong interaction shift of the kaonic 3He 2p state was determined to be -2+-2
(stat)+-4 (syst) eV.Comment: Accepted for publication in Phys. Lett.
ASPECTS REGARDING THE EPIGEE ENTOMOFAUNE EXISTING IN SOME AGRICULTURAL CROPS
Observations were made in 2016 in apple tree plantations, corn crops and cabbage crops belonging to the Vasile Adamachi farm, Iasi, Iasi County. The purpose of the paper was to compare the entomofauna by a number of 3 different crops as well as agroecosystem technology and conditions. The material was harvested using Barber soil traps from June until September inclusive. The collected material was cleaned of vegetal remains and was then prepared for identification at insect level. The analysis of the collected material shows that the specimens collected belong to the Hexapoda Class, with several orders of insects and the Arachnida Class, the Aranea order. Most of them belong to the Insecta class. The orders to which the species are collected are: Coleoptera, Heteroptera, Hymenoptera, Diptera, all of the Hexapoda class. Regarding the abundance of entomofauna on crops, it is found that most of the cabbage crops were collected (126) followed by apple crops (123) and then corn cultures (107).Â
A New Measurement of Kaonic Hydrogen X rays
The system at threshold is a sensitive testing ground for low
energy QCD, especially for the explicit chiral symmetry breaking. Therefore, we
have measured the -series x rays of kaonic hydrogen atoms at the DANE
electron-positron collider of Laboratori Nazionali di Frascati, and have
determined the most precise values of the strong-interaction energy-level shift
and width of the atomic state. As x-ray detectors, we used large-area
silicon drift detectors having excellent energy and timing resolution, which
were developed especially for the SIDDHARTA experiment. The shift and width
were determined to be eV and
eV, respectively. The new
values will provide vital constraints on the theoretical description of the
low-energy interaction.Comment: 5 figures, submitted to Physics Letters
Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives
[EN] Modification of GO by organic molecules changes its catalytic activity in the hydrogen transfer from i-propanol to enones, affecting the selectivity to allyl alcohol and diastereoselectivity to the resulting stereoisomers. It is noteworthy the system does not contain metals and is recyclable.Coman, SM.; Podolean, I.; Tudorache, M.; Cojocaru, B.; Parvulescu, VI.; Puche Panadero, M.; García Gómez, H. (2017). Graphene oxide as a catalyst for the diastereoselective transfer hydrogenation in the synthesis of prostaglandin derivatives. Chemical Communications. 53(74):10271-10274. doi:10.1039/c7cc05105kS1027110274537
OBSERVATIONS ON THE STRUCTURE, DYNAMICS AND ABBREVIATION OF ENTOMOFAUNE COLLECTED FROM CERTAIN AGRICULTURAL CROPS
The remarks were made in 2016 in the fruit tree, pear, peach, vine plantations, corn crops and cabbage crops, in two stations, stationary Vasile Adamachi, Iasi Iasi county and Ezereni farm in the Miroslava, Iasi County. The purpose of the paper was to compare the entomofauna by a number of different agricultural and field cultures, different as well as agroecosystem technology and conditions.The material was collected using the entomological filet, from June until September inclusive.The collected material was cleaned of vegetal remains and was then prepared for identification at species level. The analysis of the collected material shows that the samples collected belong to the Hexapoda Class, with several insect orders and the Arachnida Class, the Aranea order and the Acari order. Most of them belong to the Insecta class. The orders to which the species are collected are: Coleoptera, Heteroptera, Hymenoptera, Diptera, all of the Hexapoda class. As regards the abundance entomofauna, cultures, it is found that the wheat had been collected the multiple copies (69) followed by the growing of maize (39) and then planting vine (29) and plantations apple (24)
CONGAS: a collaborative ontology development framework based on Named GrAphS
The process of ontology development involves a range of skills and know-how often requiring team work of different people, each of them with his own way of contributing to the definition and formalization of the domain representation. For this reason, collaborative development is an important feature for ontology editing tools, and should take into account the different characteristics of team participants, provide them with a dedicated working environment allowing to express their ideas and creativity, still protecting integrity of the shared work. In this paper we present CONGAS, a collaborative version of the Knowledge Management and Acquisition platform Semantic Turkey which, exploiting the potentialities brought by recent introduction of context management into RDF triple graphs, offers a collaborative environment where proposals for ontology evolution can emerge and coexist, be evaluated by team users, trusted across different perspectives and eventually converged into the main development stream
Probing magnetic fields in the circumgalactic medium using polarization data from MIGHTEE
The detection and study of magnetic fields surrounding galaxies is important
to understand galaxy evolution since magnetic fields are tracers for dynamical
processes in the circumgalactic medium (CGM) and can have a significant impact
on the evolution of the CGM. The Faraday rotation measure (RM) of the polarized
light of background radio sources passing through the magnetized CGM of
intervening galaxies can be used as a tracer for the strength and extent of
magnetic fields around galaxies. We use rotation measures observed by the
MIGHTEE-POL (MeerKAT International GHz Tiered Extragalactic Exploration
POLarisation) survey by MeerKAT in the XMM-LSS and COSMOS fields to investigate
the RM around foreground star-forming galaxies. We use spectroscopic catalogs
of star-forming and blue cloud galaxies to measure the RM of MIGHTEE-POL
sources as a function of the impact parameter from the intervening galaxy. We
then repeat this procedure using a deeper galaxy catalog with photometric
redshifts. For the spectroscopic star-forming sample we find a
redshift-corrected |RM| excess of 5.6 +/- 2.3 rad m-2 which corresponds to a
2.5 sigma significance around galaxies with a median redshift of z = 0.46 for
impact parameters below 130 kpc only selecting the intervenor with the smallest
impact parameter. Making use of a photometric galaxy catalog and taking into
account all intervenors with Mg < -13.6 mag, the signal disappears. We find no
indication for a correlation between redshift and RM, nor do we find a
connection between the total number of intervenors to the total |RM| . We have
presented tentative evidence that the CGM of star-forming galaxies is permeated
by coherent magnetic fields within the virial radius. We conclude that mostly
bright, star-forming galaxies with impact parameters less than 130 kpc
significantly contribute to the RM of the background radio source.Comment: 11 pages, 8 figures, accepted for publication in A&
Behavioral and physiological indicators of stress coping styles in larval zebrafish
Animal science
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