1,223 research outputs found
Quantização de Laços no Modelo BF 2+1 Dimensional com Campos de Matéria.
O objetivo deste trabalho Ă© explorar as simetrias e desenvolver a dinâmica associada a um modelo do tipo BF com campos escalares acoplados, tanto a nĂvel clássico quanto a nĂvel quântico. Para tal, desenvolvem-se ferramentas matemáticas apropriadas para se tratar
em geral uma teoria de calibre topológica do tipo Yang-Mills, para formular uma ação covariante e estudar suas simetrias via o método de quantização canônica de Dirac, também conhecido como método hamiltoniano vinculado. Este método é desenvolvido extensamente
para os casos abeliano e não-abeliano do nosso modelo, e em seguida quantiza-se o caso abeliano via laços para analisar o desenvolvimento da mecânica quântica nestas teorias
de calibre descrevendo a base para nossos funcionais de estado, chamada de rede de
cargas, bem como o c´alculo de alguns observ´aveis associados a nossos estados cinem´aticos
e f´ısicos
Desempenho Produtivo de Ovinos Barriga Negra em Roraima: 2017/2018.
bitstream/item/199615/1/COT-86-Barriga-negra.pd
Molecular genetics and pathophysiology of 17 beta-hydroxysteroid dehydrogenase 3 deficiency.
Autosomal recessive mutations in the 17 beta-hydroxysteroid dehydrogenase 3 gene impair the formation of testosterone in the fetal testis and give rise to genetic males with female external genitalia. Such individuals are usually raised as females, but virilize at the time of expected puberty as the result of increases in serum testosterone. Here we describe mutations in 12 additional subjects/families with this disorder. The 14 mutations characterized to date include 10 missense mutations, 3 splice junction abnormalities, and 1 small deletion that results in a frame shift. Three of these mutations have occurred in more than 1 family. Complementary DNAs incorporating 9 of the 10 missense mutations have been constructed and expressed in reporter cells; 8 of the 9 missense mutations cause almost complete loss of enzymatic activity. In 2 subjects with loss of function, missense mutations testosterone levels in testicular venous blood were very low. Considered together, these findings strongly suggest that the common mechanism for testosterone formation in postpubertal subjects with this disorder is the conversion of circulating androstenedione to testosterone by one or more of the unaffected 17 beta-hydroxysteroid dehydrogenase isoenzymes
Regolith behavior under asteroid-level gravity conditions: Low-velocity impacts into mm- and cm-sized grain targets
In situ observations of small asteroids show that surfaces covered by
boulders and coarse terrain are frequent on such bodies. Regolith grain sizes
have distributions on approximately mm and cm scales, and the behavior of such
large grains in the very low-gravity environments of small body surfaces
dictates their morphology and evolution. In order to support the understanding
of natural processes (e.g., the recapturing of impact ejecta) or
spacecraft-induced interactions (e.g., the fate of a small lander), we aim to
experimentally investigate the response of coarse-grained target surfaces to
very-low-speed impacts (below 2 m/s). We present the outcome of 86 low-speed
impacts of a cm-sized spherical projectile into a bed of simulated regolith,
composed of irregular mm- and cm-sized grains. These impacts were performed
under vacuum and microgravity conditions. Our results include measurements for
the projectile coefficient of restitution and penetration depth, as well as
ejecta production, speed, and mass estimation. We find that impact outcomes
include the frequent occurrence of projectile bouncing and tangential rolling
on the target surface upon impact. Ejecta is produced for impact speeds higher
than about 12 cm/s, and ejecta speeds scale with the projectile to target the
grain size ratio and the impact speed. Ejected mass estimations indicate that
ejecta is increasingly difficult to produce for increasing grain sizes.
Coefficients of restitution of rebounding projectiles do not display a
dependency on the target grain size, unlike their maximum penetration depth,
which can be scaled with the projectile to target grain size ratio. Finally, we
compare our experimental measurements to spacecraft data and numerical work on
Hayabusa 2's MASCOT landing on the surface of the asteroid Ryugu
Nonlinear electrodynamics and the Pioneer 10/11 spacecraft anomaly
The occurrence of the phenomenon known as photon acceleration is a natural
prediction of nonlinear electrodynamics (NLED). This would appear as an
anomalous frequency shift in any modeling of the electromagnetic field that
only takes into account the classical Maxwell theory. Thus, it is tempting to
address the unresolved anomalous, steady; but time-dependent, blueshift of the
Pioneer 10/11 spacecrafts within the framework of NLED. Here we show that
astrophysical data on the strength of the magnetic field in both the Galaxy and
the local (super)cluster of galaxies support the view on the major Pioneer
anomaly as a consequence of the phenomenon of photon acceleration. If
confirmed, through further observations or lab experiments, the reality of this
phenomenon should prompt to take it into account in any forthcoming research on
both cosmological evolution and origin and dynamical effects of primordial
magnetic fields, whose seeds are estimated to be very weak.Comment: Final version accepted for publication in Europhysics Letters, uses
EPL style, 7 page
Wheat cultivation: Identification and estimation of areas using LANDSAT data
The feasibility of using automatically processed multispectral data obtained from LANDSAT to identify wheat and estimate the areas planted with this grain was investigated. Three 20 km by 40 km segments in a wheat growing region of Rio Grande do Sul were aerially photographed using type 2443 Aerochrome film. Three maps corresponding to each segment were obtained from the analysis of the photographs which identified wheat, barley, fallow land, prepared soil, forests, and reforested land. Using basic information about the fields and maps made from the photographed areas, an automatic classification of wheat was made using MSS data from two different periods: July to September and July to October 1979. Results show that orbital data is not only useful in characterizing the growth of wheat, but also provides information of the intensity and extent of adverse climate which affects cultivation. The temporal and spatial characteristics of LANDSAR data are also demonstrated
Knockdown of the DNA repair and redox signaling protein Ape1/ Ref-1 blocks ovarian cancer cell and tumor growth
Apurinic endonuclease 1/redox effector factor-1 (Ape1/Ref-1 or Ape1) is an essential protein with two distinct functions. It is a DNA repair enzyme in the base excision repair (BER) pathway and a reduction–oxidation (redox) signaling factor maintaining transcription factors in an active reduced state. Our laboratory previously demonstrated that Ape1 is overexpressed in ovarian cancer and potentially contributes to resistance. Therefore, we utilized siRNA technology to knockdown protein levels of Ape1 in ovarian cancer cell line, SKOV-3x. Knocking Ape1 down had dramatic effects on cell growth in vitro but was not due to an increase in apoptosis and at least partially due to an extension in transit time through S-phase. Similarly, human ovarian tumor xenografts with reduced levels of Ape1 protein demonstrated a dramatic reduction in tumor volume (p < 0.01) and also statistically significant (p = 0.02) differences in 18F-fluorodeoxyglucose (FDG) uptake indicating reduced glucose metabolism and cellular proliferation. Ape1's role in DNA repair and redox signaling is important to our basic understanding of ovarian cancer cell growth and these findings strongly support Ape1 as a therapeutic target
Equações para estimar a composição corporal em caprinos Saanen na fase inicial de crescimento.
- …