3,804 research outputs found
The dynamical transition in proteins and non-Gaussian behavior of low frequency modes in Self Consistent Normal Mode Analysis
Self Consistent Normal Mode Analysis (SCNMA) is applied to heme c type
cytochrome f to study temperature dependent protein motion. Classical Normal
Mode Analysis (NMA) assumes harmonic behavior and the protein Mean Square
Displacement (MSD) has a linear dependence on temperature. This is only
consistent with low temperature experimental results. To connect the protein
vibrational motions between low temperature and physiological temperature, we
have incorporated a fitted set of anharmonic potentials into SCNMA. In
addition, Quantum Harmonic Oscillator (QHO) theory has been used to calculate
the displacement distribution for individual vibrational modes. We find that
the modes involving soft bonds exhibit significant non-Gaussian dynamics at
physiological temperature, which suggests it may be the cause of the
non-Gaussian behavior of the protein motions probed by Elastic Incoherent
Neutron Scattering (EINS). The combined theory displays a dynamical transition
caused by the softening of few "torsional" modes in the low frequency regime (<
50cm-1or 0.6ps). These modes change from Gaussian to a classical
distribution upon heating. Our theory provides an alternative way to understand
the microscopic origin of the protein dynamical transition.Comment: 17 pages, 6 figures, 1 tabl
Succulent feeds for dairy cows in summer
Profits in dairy operations are determined largely by the roughages available on a dairy farm. Successful dairymen plan feeding practices according to the roughages they have at hand. The kind and amount of grain they feed depends upon the roughage, being employed largely to supplement any possible deficiency in the roughages
Allelomimesis as universal clustering mechanism for complex adaptive systems
Animal and human clusters are complex adaptive systems and many are organized
in cluster sizes that obey the frequency-distribution . Exponent describes the relative abundance of the cluster
sizes in a given system. Data analyses have revealed that real-world clusters
exhibit a broad spectrum of -values, . We show that allelomimesis is a
fundamental mechanism for adaptation that accurately explains why a broad
spectrum of -values is observed in animate, human and inanimate cluster
systems. Previous mathematical models could not account for the phenomenon.
They are hampered by details and apply only to specific systems such as cities,
business firms or gene family sizes. Allelomimesis is the tendency of an
individual to imitate the actions of its neighbors and two cluster systems
yield different values if their component agents display different
allelomimetic tendencies. We demonstrate that allelomimetic adaptation are of
three general types: blind copying, information-use copying, and non-copying.
Allelomimetic adaptation also points to the existence of a stable cluster size
consisting of three interacting individuals.Comment: 8 pages, 5 figures, 2 table
Heat generation during overcharge of Ni/H2 cells
Information is given in viewgraph form on the heat generation during overcharge of nickel hydrogen cells. The heat dissipated during various rates of charge and overcharge was measured, using a radiative type calorimeter. Measurements made during the charging of the cell indicated that the total heat was greatest for C/10 charge, compared with C/2 or C/4. The endothermic to exothermic transition occurred at 1.43 V for C/10 charge, and increased to 1.467 V at C/2 charge. The magnitude of the endothermic heat was only 3.7 percent of the total heat generated during charging. Experimentally measured values were compared against those calculated using a thermoneutral potential of 1.51 V. Although there was general agreement between the calculated and measured values, a significant difference existed in the instantaneous heat values for the initial stages of cell discharge. Heat dissipated during self-discharge appears to depend on the charge rate preceding open circuit stand
Semileptonic Hyperon Decays and CKM Unitarity
Using a technique that is not subject to first-order SU(3) symmetry breaking
effects, we determine the element of the CKM matrix from data on
semileptonic hyperon decays. We obtain =0.2250(27). This value is of
similar precision to the one derived from , but higher and in better
agreement with the unitarity requirement, .Comment: 3 pages, 1 tabl
Conformal Radiotherapy Facilitates the Delivery of Concurrent Chemotherapy and Radiotherapy: A Case of Primitive Neuroectodermal Tumour of the Chest Wall
We illustrate the principle of conformal radiotherapy by discussing the case of a patient with a primitive neuroectodermal
tumour of the chest wall. Recent advances in radiotherapy planning enable precise localization of the planning target volume
(PTV) and normal organs at risk of irradiation. Customized blocks are subsequently designed to produce a treatment field
that ‘conforms’ to the PTV. The use of conformal radiotherapy (CRT) in this case facilitated the delivery of concurrent
chemotherapy and radiotherapy by significantly reducing the volume of red marrow irradiated.The lack of acute and late
toxicities was attributed to optimal exclusion of normal tissues from the treatment field, made possible by CRT
MLS antenna locations for the deHaviland DASH 7 aircraft
Several proposed aircraft antenna locations were investigated to determine their potential for satisfying the microwave landing system antenna coverage requirements. The results of this investigation are presented and antenna locations are recommended for the deHavilland DASH 7 aircraft
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