1,678 research outputs found
Quantitative insights into the cyanobacterial cell economy
© Zavřel et al. Phototrophic microorganisms are promising resources for green biotechnology. Compared to heterotrophic microorganisms, however, the cellular economy of phototrophic growth is still insufficiently understood. We provide a quantitative analysis of light-limited, light-saturated, and light-inhibited growth of the cyanobacterium Synechocystis sp. PCC 6803 using a reproducible cultivation setup. We report key physiological parameters, including growth rate, cell size, and photosynthetic activity over a wide range of light intensities. Intracellular proteins were quantified to monitor proteome allocation as a function of growth rate. Among other physiological acclimations, we identify an upregulation of the translational machinery and downregulation of light harvesting components with increasing light intensity and growth rate. The resulting growth laws are discussed in the context of a coarse-grained model of phototrophic growth and available data obtained by a comprehensive literature search. Our insights into quantitative aspects of cyanobacterial acclimations to different growth rates have implications to understand and optimize photosynthetic productivity
A Monte Carlo simulation of ion transport at finite temperatures
We have developed a Monte Carlo simulation for ion transport in hot
background gases, which is an alternative way of solving the corresponding
Boltzmann equation that determines the distribution function of ions. We
consider the limit of low ion densities when the distribution function of the
background gas remains unchanged due to collision with ions. A special
attention has been paid to properly treat the thermal motion of the host gas
particles and their influence on ions, which is very important at low electric
fields, when the mean ion energy is comparable to the thermal energy of the
host gas. We found the conditional probability distribution of gas velocities
that correspond to an ion of specific velocity which collides with a gas
particle. Also, we have derived exact analytical formulas for piecewise
calculation of the collision frequency integrals. We address the cases when the
background gas is monocomponent and when it is a mixture of different gases.
The developed techniques described here are required for Monte Carlo
simulations of ion transport and for hybrid models of non-equilibrium plasmas.
The range of energies where it is necessary to apply the technique has been
defined. The results we obtained are in excellent agreement with the existing
ones obtained by complementary methods. Having verified our algorithm, we were
able to produce calculations for Ar ions in Ar and propose them as a new
benchmark for thermal effects. The developed method is widely applicable for
solving the Boltzmann equation that appears in many different contexts in
physics.Comment: 14 page
Field-based tests for the assessment of physical fitness in children and adolescents practicing sport: A systematic review within the ESA program
High levels of physical fitness (PF) can positively affect both health and cognitive function, thus monitoring its levels in youth can help increase health and quality of life in adult populations later on. This systematic review aims to identify PF field-based tests used in young European populations practicing sport to find tools that are adequate for the considered target involving a new battery within the Enriched Sport Activities (ESA) project. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement was followed. In the 83 identified articles, the main tests used were: vertical/horizontal jumps (for muscular strength/power); push-ups, running at maximum effort, sit-ups (for muscular strength/endurance); multistage non-intermittent and intermittent tests (for aerobic endurance); sit and reach (for flexibility); sprinting and agility T-tests (for speed and agility, respectively); 10 x 5 m shuttle run (SR) (for both speed and agility). Few studies assessed coordination, reaction time, power, and balance. Although the selected tests are widely used and validated, they do not determine all PF aspects and do not reflect sport-specific features. A final decision was made for the inclusion of the following tests: standing broad jump, seated medicine ball throw, 20 m SR test, 30 m sprint, Illinois test, and a new test, i.e., the crunning test, to assess different skill-related components at once. The use of this combination of tests allows for the assessment of all PF components and can help planning eective training programs and cultivate sporting talent
Plasmon excitations and 1D - 2D dimensional crossover in quantum crossbars
Spectrum of boson fields and two-point correlators are analyzed in quantum
crossbars (QCBs, a superlattice formed by m crossed interacting arrays of
quantum wires), with short range inter-wire capacitive interaction. Spectral
and correlation properties of double (m=2) and triple (m-3) QCBs are studied.
It is shown that the standard bosonization procedure is valid, and the system
behaves as a sliding Luttinger liquid in the infrared limit, but the high
frequency spectral and correlation characteristics have either 1D or 2D nature
depending on the direction of the wave vector in the 2D elementary cell of
reciprocal lattice. As a result, the crossover from 1D to 2D regime may be
experimentally observed. It manifests itself as appearance of additional peaks
of optical absorption, non-zero transverse space correlators and periodic
energy transfer between arrays ("Rabi oscillations")
Avaliação biométrica de laranjeiras utilizando o limoeiro cravo como porta-enxerto e espaçamento adensado no Semiárido cearense.
O objetivo deste trabalho é realizar a avaliação biométrica de copas de laranjeiras sobre o limoeiro Cravo no Semiárido cearense
Multiwavelength Observations of Supersonic Plasma Blob Triggered by Reconnection Generated Velocity Pulse in AR10808
Using multi-wavelength observations of Solar and Heliospheric Observatory
(SoHO)/Michelson Doppler Imager (MDI), Transition Region and Coronal Explorer
(TRACE) 171 \AA, and H from Culgoora Solar Observatory at Narrabri,
Australia, we present a unique observational signature of a propagating
supersonic plasma blob before an M6.2 class solar flare in AR10808 on 9th
September 2005. The blob was observed between 05:27 UT to 05:32 UT with almost
a constant shape for the first 2-3 minutes, and thereafter it quickly vanished
in the corona. The observed lower bound speed of the blob is estimated as
215 km s in its dynamical phase. The evidence of the blob with
almost similar shape and velocity concurrent in H and TRACE 171 \AA\
supports its formation by multi-temperature plasma. The energy release by a
recurrent 3-D reconnection process via the separator dome below the magnetic
null point, between the emerging flux and pre-existing field lines in the lower
solar atmosphere, is found to be the driver of a radial velocity pulse outwards
that accelerates this plasma blob in the solar atmosphere. In support of
identification of the possible driver of the observed eruption, we solve the
two-dimensional ideal magnetohydrodynamic equations numerically to simulate the
observed supersonic plasma blob. The numerical modelling closely match the
observed velocity, evolution of multi-temperature plasma, and quick vanishing
of the blob found in the observations. Under typical coronal conditions, such
blobs may also carry an energy flux of 7.0 ergs cm
s to re-balance the coronal losses above active regions.Comment: Solar Physics; 22 Pages; 8 Figure
Technology-assisted stroke rehabilitation in Mexico: a pilot randomized trial comparing traditional therapy to circuit training in a Robot/technology-assisted therapy gym
Background Stroke rehabilitation in low- and middle-income countries, such as Mexico, is often hampered by lack of clinical resources and funding. To provide a cost-effective solution for comprehensive post-stroke rehabilitation that can alleviate the need for one-on-one physical or occupational therapy, in lower and upper extremities, we proposed and implemented a technology-assisted rehabilitation gymnasium in Chihuahua, Mexico. The Gymnasium for Robotic Rehabilitation (Robot Gym) consisted of low- and high-tech systems for upper and lower limb rehabilitation. Our hypothesis is that the Robot Gym can provide a cost- and labor-efficient alternative for post-stroke rehabilitation, while being more or as effective as traditional physical and occupational therapy approaches. Methods A typical group of stroke patients was randomly allocated to an intervention (n = 10) or a control group (n = 10). The intervention group received rehabilitation using the devices in the Robot Gym, whereas the control group (n = 10) received time-matched standard care. All of the study subjects were subjected to 24 two-hour therapy sessions over a period of 6 to 8 weeks. Several clinical assessments tests for upper and lower extremities were used to evaluate motor function pre- and post-intervention. A cost analysis was done to compare the cost effectiveness for both therapies. Results No significant differences were observed when comparing the results of the pre-intervention Mini-mental, Brunnstrom Test, and Geriatric Depression Scale Test, showing that both groups were functionally similar prior to the intervention. Although, both training groups were functionally equivalent, they had a significant age difference. The results of all of the upper extremity tests showed an improvement in function in both groups with no statistically significant differences between the groups. The Fugl-Meyer and the 10 Meters Walk lower extremity tests showed greater improvement in the intervention group compared to the control group. On the Time Up and Go Test, no statistically significant differences were observed pre- and post-intervention when comparing the control and the intervention groups. For the 6 Minute Walk Test, both groups presented a statistically significant difference pre- and post-intervention, showing progress in their performance. The robot gym therapy was more cost-effective than the traditional one-to-one therapy used during this study in that it enabled therapist to train up to 1.5 to 6 times more patients for the approximately same cost in the long term. Conclusions The results of this study showed that the patients that received therapy using the Robot Gym had enhanced functionality in the upper extremity tests similar to patients in the control group. In the lower extremity tests, the intervention patients showed more improvement than those subjected to traditional therapy. These results support that the Robot Gym can be as effective as traditional therapy for stroke patients, presenting a more cost- and labor-efficient option for countries with scarce clinical resources and funding. Trial registration ISRCTN98578807
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Genetic Circuitry of Survival Motor Neuron, the Gene Underlying Spinal Muscular Atrophy
The clinical severity of the neurodegenerative disorder spinal muscular atrophy (SMA) is dependent on the levels of functional Survival Motor Neuron (SMN) protein. Consequently, current strategies for developing treatments for SMA generally focus on augmenting SMN levels. To identify additional potential therapeutic avenues and achieve a greater understanding of SMN, we applied in vivo, in vitro, and in silico approaches to identify genetic and biochemical interactors of the Drosophila SMN homolog. We identified more than 300 candidate genes that alter an Smn-dependent phenotype in vivo. Integrating the results from our genetic screens, large-scale protein interaction studies, and bioinformatic analysis, we define a unique interactome for SMN that provides a knowledge base for a better understanding of SMA.Stem Cell and Regenerative Biolog
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