2,422 research outputs found
Wind speed statistics for Goldstone, California, anemometer sites
An exploratory wind survey at an antenna complex was summarized statistically for application to future windmill designs. Data were collected at six locations from a total of 10 anemometers. Statistics include means, standard deviations, cubes, pattern factors, correlation coefficients, and exponents for power law profile of wind speed. Curves presented include: mean monthly wind speeds, moving averages, and diurnal variation patterns. It is concluded that three of the locations have sufficiently strong winds to justify consideration for windmill sites
Using Entropy-Based Methods to Study General Constrained Parameter Optimization Problems
In this letter we propose the use of physics techniques for entropy
determination on constrained parameter optimization problems. The main feature
of such techniques, the construction of an unbiased walk on energy space,
suggests their use on the quest for optimal solutions of an optimization
problem. Moreover, the entropy, and its associated density of states, give us
information concerning the feasibility of solutions.Comment: 10 pages, 3 figures, references correcte
Thermodynamic restrictions on evolutionary optimization of transcription factor proteins
Conformational fluctuations are believed to play an important role in the
process by which transcription factor proteins locate and bind their target
site on the genome of a bacterium. Using a simple model, we show that the
binding time can be minimized, under selective pressure, by adjusting the
spectrum of conformational states so that the fraction of time spent in more
mobile conformations is matched with the target recognition rate. The
associated optimal binding time is then within an order of magnitude of the
limiting binding time imposed by thermodynamics, corresponding to an idealized
protein with instant target recognition. Numerical estimates suggest that
typical bacteria operate in this regime of optimized conformational
fluctuations
Coevolution of agents and networks: Opinion spreading and community disconnection
We study a stochastic model for the coevolution of a process of opinion
formation in a population of agents and the network which underlies their
interaction. Interaction links can break when agents fail to reach an opinion
agreement. The structure of the network and the distribution of opinions over
the population evolve towards a state where the population is divided into
disconnected communities whose agents share the same opinion. The statistical
properties of this final state vary considerably as the model parameters are
changed. Community sizes and their internal connectivity are the quantities
used to characterize such variations.Comment: To appear in Phys. Lett.
Implicit theories of a desire for fame
The aim of the present studies was to generate implicit theories of a desire for fame among the general population. In Study 1, we were able to develop a nine-factor analytic
model of conceptions of the desire to be famous that initially comprised nine separate factors; ambition, meaning derived through comparison with others, psychologically vulnerable, attention seeking, conceitedness, social access, altruistic, positive affect, and glamour. Analysis that sought to examine replicability among these factors suggested that three factors (altruistic, positive affect, and glamour) neither display factor congruence nor display adequate internal reliability. A second study examined the validity of these factors in predicting profiles of individuals who may desire fame. The findings from this study suggested that two of the nine factors (positive affect and
altruism) could not be considered strong factors within the model. Overall, the findings suggest that implicit theories of a desire for fame comprise six factors. The discussion
focuses on how an implicit model of a desire for fame might progress into formal theories of a desire for fame
Kinetics of protein-DNA interaction: facilitated target location in sequence-dependent potential
Recognition and binding of specific sites on DNA by proteins is central for
many cellular functions such as transcription, replication, and recombination.
In the process of recognition, a protein rapidly searches for its specific site
on a long DNA molecule and then strongly binds this site. Here we aim to find a
mechanism that can provide both a fast search (1-10 sec) and high stability of
the specific protein-DNA complex ( M).
Earlier studies have suggested that rapid search involves the sliding of a
protein along the DNA. Here we consider sliding as a one-dimensional (1D)
diffusion in a sequence-dependent rough energy landscape. We demonstrate that,
in spite of the landscape's roughness, rapid search can be achieved if 1D
sliding is accompanied by 3D diffusion. We estimate the range of the specific
and non-specific DNA-binding energy required for rapid search and suggest
experiments that can test our mechanism. We show that optimal search requires a
protein to spend half of time sliding along the DNA and half diffusing in 3D.
We also establish that, paradoxically, realistic energy functions cannot
provide both rapid search and strong binding of a rigid protein. To reconcile
these two fundamental requirements we propose a search-and-fold mechanism that
involves the coupling of protein binding and partial protein folding.
Proposed mechanism has several important biological implications for search
in the presence of other proteins and nucleosomes, simultaneous search by
several proteins etc. Proposed mechanism also provides a new framework for
interpretation of experimental and structural data on protein-DNA interactions
Thermodynamics of aggregation of two proteins
We investigate aggregation mechanism of two proteins in a thermodynamically
unambiguous manner by considering the finite size effect of free energy
landscape of HP lattice protein model. Multi-Self-Overlap-Ensemble Monte Carlo
method is used for numerical calculations. We find that a dimer can be formed
spontaneously as a thermodynamically stable state when the system is small
enough. It implies the possibility that the aggregation of proteins in a cell
is triggered when they are confined in a small region by, for example, being
surrounded by other macromolecules.We also find that the dimer exhibits a
transition between unstable state and metastable state in the infinite system.Comment: jpsj2.cls, 7 pages, 14 figures; misconfigurations of Fig.Nos.
correcte
Методологія визначення оптимальних технологічних параметрів транспортної інфраструктури при обслуговуванні зернових вантажопотоків
Комплексно проаналізовано на прикладі функціонування багатоканальної динамічної системи з кінцевим числом степенів свободи можливість покращення економічних показників транспортної системи при узгодженні інфраструктурних параметрів для обслуговування підприємств елеваторно-складського господарства. Охарактеризована залежність числового значення логістичних витрат в системі з двома вузлами обслуговування.Комплексно проанализирована на примере функционирования многоканальной динамической системы с конечным числом степеней свободы возможность улучшения экономических показателей транспортной системы при согласовании инфраструктурных параметров для обслуживания предприятий элеваторно-складского хазяйства. Охарактеризована зависимость числового значения логистических расходов в системе с двумя узлами обслуживания.In possibility of improving the economic indicators of a transport system is fully analyzed in the concordance of infrastructural parameters for maintenance of elevator-store enterprises with using, as an example, functioning of a multichannel dynamic system with the finite number of degrees of freedom. The numerical value of logistic charges for the system with two knots is described
Normohomocysteinaemia and vitamin-treated hyperhomocysteinaemia are associated with similiar risks of cardiovascular events in patients with premature peripheral arterial occlusive disease. A prospective cohort study
Objectives. Mild hyperhomocysteinaemia (HHC), fasting or after methionine loading, is associated with an increased risk and severity of atherosclerotic vascular disease. Post-methionine and fasting HHC are responsive to treatment with vitamin
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