291 research outputs found
Structure of Fat Jets at the Tevatron and Beyond
Boosted resonances is a highly probable and enthusiastic scenario in any
process probing the electroweak scale. Such objects when decaying into jets can
easily blend with the cornucopia of jets from hard relative light QCD states.
We review jet observables and algorithms that can contribute to the
identification of highly boosted heavy jets and the possible searches that can
make use of such substructure information. We also review previous studies by
CDF on boosted jets and its measurements on specific jet shapes.Comment: invited review for a special "Top and flavour physics in the LHC era"
issue of The European Physical Journal C, we invite comments regarding
contents of the review; v2 added references and institutional preprint
number
EFEITO DA IDADE DA MATRIZ NO TEMPO DE ECLOSÃO, TEMPO DE PERMANÊNCIA DO NEONATO NO NASCEDOURO E O PESO DO PINTAINHO
Six hundred eggs from 32, 43 and 60 week-old Cobb-500® broiler breeder were incubated at 37,8°C and 60% of humidity. It was used a completely randomized design with three treatments (broiler breeder ages) and 200 repetitions (each embryo/chick was considered a repetition). Eggs were weighted at 1st and 19 th days, weight losses during the incubation were estimated, chicks were weighted at birth and when they were removed from hatchery and weight losses during this period were measured. Eggs and chicks from older broiler breeder were heavier. There were no differences in relation to egg weight losses, on chick weight percentages (chick weight/egg weight ratio), of incubation time (h) and on the weight losses during their hatchery remaining. Considering 32, 43 and 60 week-old broiler breeder, respectively, initial egg weight was highly and positively correlated with egg weight at 19 th day of incubation (0.75; 0.86 and 0.79), with birth chick weight (0.57, 0.72, 0.72) and with chick weight at hatchery removing (0.38, 0.41, 0.51); positive correlations (0.61,0.41 and 0.63) were observed between incubation time and chick weight. Negative correlations (-0.79, -0.96 and -0.76) were found between incubation time and chick weight losses during hatchery remaining. In conclusion, broiler breeder age affected egg and chick weight. Eggs from different broiler breeder ages might be incubated during the same period without affecting the quality of newborn in function of the time spends in hatchery.Utilizaram-se 600 ovos embrionados, provenientes de matrizes de 32, 43 e 60 semanas de idade, da linhagem Cobb – 500, incubados a 37,8°C e 60% de umidade. Foram analisados peso do ovo, peso dos ovos aos 19 dias de incubação, tempo de incubação, perda de peso do ovo durante a incubação, peso dos pintainhos no momento do nascimento e na retirada do nascedouro e perda de peso do pintainho no nascedouro. Foi utilizado um delineamento inteiramente ao acaso com 3 tratamentos (idade da matriz) e 200 repetições (cada ovo foi considerado uma repetição). Os resultados foram submetidos à análise de variância e Teste de Tukey (5%). Matrizes mais velhas produziram ovos mais pesados. Não houve diferença na perda de peso de ovos, no percentual de peso dos pintainhos, no tempo de incubação (h) e também na perda de peso do pintainho no nascedouro. Houve uma correlação positiva (0,75; 0,86; 0,79 respectivamente para matrizes de 32, 43 e 60 semanas) entre o peso inicial dos ovos e o peso dos ovos aos 19 dias de incubação, com o peso do pintainho, no momento do nascimento (0,57; 0,72; 0,72) e no momento da retirada do nascedouro (0,38; 0,41; 0,51). Também houve correlação (0,61; 0,41 e 0,63) entre o tempo de incubação e o peso do pintainho e com a perda de peso do pintainho no nascedouro (-0,79; -0,96; -0,76). Conclui-se que a idade da reprodutora afeta o peso do ovo e do pintainho. Ovos de matrizes de diferentes idades necessitam o mesmo tempo para incubação
Magnetic hyperthermia experiments with magnetic nanoparticles in clarified butter oil and paraffin: A thermodynamic analysis
In specific power absorption models for magnetic fluid hyperthermia (MFH) experiments, the magnetic relaxation time of nanoparticles (NPs) is known to be a fundamental descriptor of the heating mechanisms. The relaxation time is mainly determined by the interplay between the magnetic properties of NPs and the rheological properties of NPs’ environment. Although the role of magnetism in MFH has been extensively studied, the thermal properties of the NP medium and their changes during MFH experiments have been underrated so far. Herein, we show that ZnxFe3-xO4 NPs dispersed through different media with phase transition in the temperature range of experiment as clarified butter oil (CBO) and paraffin. These systems show nonlinear behavior of the heating rate within the temperature range of MFH experiments. For CBO, a fast increase at ~306 K is associated with changes in the viscosity (¿(T)) and specific heat (cp(T)) of the medium at its melting temperature. This increment in the heating rate takes place around 318 K for paraffin. The magnetic and morphological characterization of NPs together with the observed agglomeration of NPs above 306 and 318 K for CBO and paraffin, respectively, indicate that the fast increase in MFH curves could not be associated with the change in the magnetic relaxation mechanism, with Neél relaxation being dominant. In fact, successive experimental runs performed up to temperatures below and above the CBO and paraffin melting points resulted in different MFH curves due to agglomeration of NPs driven by magnetic field inhomogeneity during the experiments. Our results highlight the relevance of the thermodynamic properties of the system NP-medium for an accurate measurement of the heating efficiency for in vitro and in vivo environments, where the thermal properties are largely variable within the temperature window of MFH experiments
Multiscale magnetic underdense regions on the solar surface: Granular and Mesogranular scales
The Sun is a non-equilibrium dissipative system subjected to an energy flow
which originates in its core. Convective overshooting motions create
temperature and velocity structures which show a temporal and spatial
evolution. As a result, photospheric structures are generally considered to be
the direct manifestation of convective plasma motions. The plasma flows on the
photosphere govern the motion of single magnetic elements. These elements are
arranged in typical patterns which are observed as a variety of multiscale
magnetic patterns. High resolution magnetograms of quiet solar surface revealed
the presence of magnetic underdense regions in the solar photosphere, commonly
called voids, which may be considered a signature of the underlying convective
structure. The analysis of such patterns paves the way for the investigation of
all turbulent convective scales from granular to global. In order to address
the question of magnetic structures driven by turbulent convection at granular
and mesogranular scales we used a "voids" detection method. The computed voids
distribution shows an exponential behavior at scales between 2 and 10 Mm and
the absence of features at 5-10 Mm mesogranular scales. The absence of
preferred scales of organization in the 2-10 Mm range supports the multiscale
nature of flows on the solar surface and the absence of a mesogranular
convective scale
Effects of Zn Substitution in the Magnetic and Morphological Properties of Fe-Oxide-Based Core-Shell Nanoparticles Produced in a Single Chemical Synthesis
Magnetic, compositional, and morphological properties of Zn-Fe-oxide core-shell bimagnetic nanoparticles were studied for three samples with 0.00, 0.06, and 0.10 Zn/Fe ratios, as obtained from particle-induced X-ray emission analysis. The bimagnetic nanoparticles were produced in a one-step synthesis by the thermal decomposition of the respective acetylacetonates. The nanoparticles present an average particle size between 25 and 30 nm as inferred from transmission electron microscopy (TEM). High-resolution TEM images clearly show core-shell morphology for the particles in all samples. The core is composed by an antiferromagnetic (AFM) phase with a Wüstite (Fe1-yO) structure, whereas the shell is composed by a ZnxFe3-xO4 ferrimagnetic (FiM) spinel phase. Despite the low solubility of Zn in the Wüstite, electron energy-loss spectroscopy analysis indicates that Zn is distributed almost homogeneously in the whole nanoparticle. This result gives information on the formation mechanisms of the particle, indicating that the Wüstite is formed first, and the superficial oxidation results in the FiM ferrite phase with similar Zn concentration than the core. Magnetization and in-field Mössbauer spectroscopy of the Zn-richest nanoparticles indicate that the AFM phase is strongly coupled to the FiM structure of the ferrite shell, resulting in a bias field (HEB) appearing below TNFeO, with HEB values that depend on the core-shell relative proportion. Magnetic characterization also indicates a strong magnetic frustration for the samples with higher Zn concentration, even at low temperatures
VFISV: Very Fast Inversion of the Stokes Vector for the Helioseismic and Magnetic Imager
In this paper we describe in detail the implementation and main properties of
a new inversion code for the polarized radiative transfer equation (VFISV: Very
Fast inversion of the Stokes vector). VFISV will routinely analyze pipeline
data from the Helioseismic and Magnetic Imager (HMI) on-board of the Solar
Dynamics Observatory (SDO). It will provide full-disk maps (40964096
pixels) of the magnetic field vector on the Solar Photosphere every 10 minutes.
For this reason VFISV is optimized to achieve an inversion speed that will
allow it to invert 16 million pixels every 10 minutes with a modest number
(approx. 50) of CPUs. Here we focus on describing a number of important
details, simplifications and tweaks that have allowed us to significantly speed
up the inversion process. We also give details on tests performed with data
from the spectropolarimeter on-board of the Hinode spacecraft.Comment: 23 pages, 9 figures (2 color). Submitted for publication to Solar
Physic
The reaction in ion-ion collisions
We study the threshold -meson production in the process , which appears as a possible important mechanism in high energy
nuclei-nuclei collisions. The isotopic invariance of the strong interaction and
the selection rules due to P-parity and total angular momentum result in a
general and model independent parametrization of the spin structure of the
matrix element in terms of three partial amplitudes. In the framework of
one-pion exchange model these amplitudes can be derived in terms of the two
threshold partial amplitudes for the process . We predict the
ratio of cross sections for meson production in - and -collisions and the polarization properties of the -meson, in
, as a function of a single parameter, which
characterizes the relative role of transversal and longitudinal -meson
polarizations in the process .Comment: 10 pages 3 figure
Vision-based portuguese sign language recognition system
Vision-based hand gesture recognition is an area of active current research in computer vision and machine learning. Being a natural way of human interaction, it is an area where many researchers are working on, with the goal of making human computer interaction (HCI) easier and natural, without the need for any extra devices. So, the primary goal of gesture recognition research is to create systems, which can identify specific human gestures and use them, for example, to convey information. For that, vision-based hand gesture interfaces require fast and extremely robust hand detection, and gesture recognition in real time. Hand gestures are a powerful human communication modality with lots of potential applications and in this context we have sign language recognition, the communication method of deaf people. Sign lan- guages are not standard and universal and the grammars differ from country to coun- try. In this paper, a real-time system able to interpret the Portuguese Sign Language is presented and described. Experiments showed that the system was able to reliably recognize the vowels in real-time, with an accuracy of 99.4% with one dataset of fea- tures and an accuracy of 99.6% with a second dataset of features. Although the im- plemented solution was only trained to recognize the vowels, it is easily extended to recognize the rest of the alphabet, being a solid foundation for the development of any vision-based sign language recognition user interface system
Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
The chromosphere is a thin layer of the solar atmosphere that bridges the
relatively cool photosphere and the intensely heated transition region and
corona. Compressible and incompressible waves propagating through the
chromosphere can supply significant amounts of energy to the interface region
and corona. In recent years an abundance of high-resolution observations from
state-of-the-art facilities have provided new and exciting ways of
disentangling the characteristics of oscillatory phenomena propagating through
the dynamic chromosphere. Coupled with rapid advancements in
magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly
investigate the role waves play in supplying energy to sustain chromospheric
and coronal heating. Here, we review the recent progress made in
characterising, categorising and interpreting oscillations manifesting in the
solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review
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