1,497 research outputs found
Cumulative particle production as a rare event
The generalization of the Glauber formula for cumulative production events is
derived. On its basis the multiplicity distribution in such events is related
to the one in the minimum bias events. As compared to the rare events of type
, the formula involves a shift in the arguments determined by the
multiplicity from a collision with a cluster of several nucleons.Comment: 11 pages, LaTe
Melvin universe as a limit of the C-metric
It is demonstrated that the Melvin universe representing the spacetime with a
strong 'homogeneous' electric field can by obtained from the spacetime of two
accelerated charged black holes by a suitable limiting procedure. The behavior
of various invariantly defined geometrical quantities in this limit is also
studied.Comment: 5 pages, no figures [v2: two references added
Muscular function and functional mobility of faller and non-faller elderly women with osteoarthritis of the knee
Falls are a major concern in the elderly population with chronic joint disease. To compare muscular function and functional mobility among older women with knee osteoarthritis with and without a history of falls, 15 elderly women with a history of falls (74.20 ± 4.46 years) and 15 without a history of falls (71.73 ± 4.73 years) were studied. Muscular function, at the angular speed of 60, 120, and 180º/s, was evaluated using the Biodex Isokinetic Dynamometer. The sit-to-stand task was performed using the Balance Master System and the Timed Up and Go test was used to determine functional mobility. After collection of these data, the history of falls was investigated. A statistically significant difference was detected in the time taken to transfer the center of gravity during the sit-to-stand test (means ± SD; non-fallers: 0.35 ± 0.16 s; fallers: 0.55 ± 0.32 s; P = 0.049, Student t-test) and in the Timed Up and Go test (medians; non-fallers: 10.08 s; fallers: 11.59 s; P = 0.038, Mann-Whitney U-test). The results indicated that elderly osteoarthritic women with a history of falls presented altered functional mobility and needed more time to transfer the center of gravity in the sit-to-stand test. It is important to implement strategies to guarantee a better functional performance of elderly patients to reduce fall risks
Nitrogen mineralized during sorghum growth after soil incorporation of different winter cover crops
Growing catch crops during the autumn/winter period is a strategy of high ecological significance since it allows reducing the residual inorganic-N present in the soil after the summer season (Rodrigues et al., 2002). Thus, winter catch crops reduce the risk of denitrification and nitrate leaching associated to the excess of rain of the autumn/winter months. Incidentally, the evergreen systems confer several other additional benefits, including protection against soil erosion and increasing soil organic matter. In recent years, agronomists and soil scientists have studied the pros and cons of the introduction of cover crops/catch crops in different agro-ecological conditions and cropping systems. Some were focused in comparing the performance of different plant species when they were used as catch crops (Jensen, 1992; Chapot and Robin, 1994). In addition, since winter catch crops precedes summer cash crops, it is important to know the effect of the catch crop in the performance of the cash crop. As a general rule, the catch crop should present good growth rate in winter and improve soil fertility to promote the growth of the summer crop. Theoretically, lupine (Lupinus albus) seems to have both features. It is a species of high biomass production in autumn/winter period (Rodrigues et al., 2013) and, being a legume species with tissues of low C/N ratio, net nitrogen mineralization should occur early in the growing season of the crop that follows lupine in the rotation. In this work, results are presented of the effect of several winter cover crops in nitrogen availability in a soil cultivated with sorghum in the following summer season
Evaluation of the effect of Musa paradisiaca L. rhizome on Saccharomyces glucose absorption and DPPH free radical scavenging capacity
Introduction: Musa paradisiaca is a common edible plant used in traditional medical systems for its medicinal properties. In this study, in vitro anti-hyperglycaemic potential and in vitro antioxidant activity of M. paradisiaca rhizome were investigated. Methods: Dried rhizome of M. paradisiaca was sequentially extracted to hexane and dichloromethane using cold maceration technique. Stock concentrations of hexane extract (35.35 mg/mL) and dichloromethane extract (22.14 mg/mL) were diluted to prepare different concentrations and were used to evaluate the effects of plant extracts on glucose uptake potential by yeast cells and DPPH free radical scavenging capacity compared to metformin and ascorbic acid standards respectively. Results: The extracts improved the glucose uptake through yeast plasma membrane, since a linear relationship in glucose uptake by yeast cells wasobserved with gradual increase in concentration of the plant extract. In terms of glucose adsorption capacity, dichloromethane extract of plant possessed a significant (p<0.05) activity compared to the hexane extract at higher glucose concentrations, but this activity was significantly less compared to metformin standard (p<0.05). Further, dichloromethane extract demonstrated a higher level of glucose adsorption potential than hexane extract. Same extract had the highest DPPH radical scavenging potential in antioxidant assay. However, this activity was concentration-dependent, and both extracts showed lower radical scavenging potentials compared to the ascorbic acid standard. Conclusion: Dichloromethane extract of M. paradisiaca rhizome is more biologically active compared to its hexane extract in terms of in vitro glucose adsorption potential and antioxidant properties. However, both extracts showed significantly lower activity compared to metformin in glucose uptake assay while ascorbic acid showed the highest activity in free radical scavenging.
Keywords: DPPH, Glucose adsorption, Musa paradisiaca rhizome, Saccharomyce
Elliptic flow from color strings
It is shown that the elliptic flow can be successfully described in the color
string picture with fusion and percolation provided anisotropy of particle
emission from the fused string is taken into account. Two possible sources of
this anisotropy are considered, propagation of the string in the transverse
plane and quenching of produced particles in the strong color field of the
string. Calculations show that the second source gives an overwhelming
contribution to the flow at accessible energies.Comment: 23 pages, 11 figure
On infinite walls in deformation quantization
We examine the deformation quantization of a single particle moving in one
dimension (i) in the presence of an infinite potential wall, (ii) confined by
an infinite square well, and (iii) bound by a delta function potential energy.
In deformation quantization, considered as an autonomous formulation of quantum
mechanics, the Wigner function of stationary states must be found by solving
the so-called \*-genvalue (``stargenvalue'') equation for the Hamiltonian.
For the cases considered here, this pseudo-differential equation is difficult
to solve directly, without an ad hoc modification of the potential. Here we
treat the infinite wall as the limit of a solvable exponential potential.
Before the limit is taken, the corresponding \*-genvalue equation involves
the Wigner function at momenta translated by imaginary amounts. We show that it
can be converted to a partial differential equation, however, with a
well-defined limit. We demonstrate that the Wigner functions calculated from
the standard Schr\"odinger wave functions satisfy the resulting new equation.
Finally, we show how our results may be adapted to allow for the presence of
another, non-singular part in the potential.Comment: 22 pages, to appear in Annals of Physic
The genus Huperzia (Lycopodiaceae) in the Azores and Madeira
The taxonomy and nomenclature of the genus Huperzia Bernh. in the Azores and Madeira have been reviewed.
Plants collected in the Azores and Madeira were characterized morphologically. The independence between two
endemic species common to Madeira and the Azores Islands – Huperzia suberecta (Lowe) Tardieu and Huperzia
dentata (Herter) Holub – is clearly shown. A clear-cut morphological separation between these taxa and Huperzia
selago (L.) Bernh. ex Schrank & Mart. of continental Europe is established
The genus Huperzia (Lycopodiaceae) in the Azores and Madeira
The taxonomy and nomenclature of the genus Huperzia Bernh. in the Azores and Madeira have been reviewed.
Plants collected in the Azores and Madeira were characterized morphologically. The independence between two
endemic species common to Madeira and the Azores Islands – Huperzia suberecta (Lowe) Tardieu and Huperzia
dentata (Herter) Holub – is clearly shown. A clear-cut morphological separation between these taxa and Huperzia
selago (L.) Bernh. ex Schrank & Mart. of continental Europe is established
Anisotropic flows from colour strings: Monte-Carlo simulations
By direct Monte-Carlo simulations it is shown that the anisotropic flows can
be successfully described in the colour string picture with fusion and
percolation provided anisotropy of particle emission from the fused string is
taken into account. Quenching of produced particles in the strong colour field
of the string is the basic mechanism for this anisotropy. The concrete
realization of this mechanism is borrowed from the QED. Due to dependence of
this mechanism on the external field strength the found flows grow with energy,
with values for at LHC energies greater by ~15% than at RHIC energies.Comment: New version with a non-static distribution of string
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