1,388,078 research outputs found
Three Sources of Errors in The Ehrenfest Treatment of Inelastic Scattering and Possible Ways of Resolving Them
In order to identify the origin of possible errors in the mixed quantum/classical approach to inelastic scattering [A. Semenov and D. Babikov, J. Chem. Phys. 140, 044306 (2014) and A. Semenov, M.-L. Dubernet, and D. Babikov, J. Chem. Phys. 141, 114304 (2014)], a simplified model is considered that consists of one intermolecular degree of freedom and two intramolecular states, coupled by a simple potential. For this system, analytic derivations are carried out to determine (i) the exact quantum mechanical solutionof the inelastic scattering problem, (ii) a simplified version of it with all oscillatory terms neglected, and (iii) the Ehrenfest solution in which the translational motion is described by the mean-field trajectory while the internal molecular motion is treated by the time-dependent Schrodinger equation. It is shown that the appropriate choice of velocity for the mean-fieldtrajectory permits to enforce microscopic reversibility and gives results in excellent agreement with full-quantum results. The average velocity method of Billing is rigorously derived as a limiting case (of this more general approach), when reversibility is enforced locally, at the initial moment of time only. It is demonstrated that errors of state-to-state transition probabilities in the Ehrenfest approach occur at lower values of total energy E if the magnitudes of excitation energy ΔE, potential energy difference between the two states ΔV, and coupling of two states V12 are large. Possible ways of applying this concept to rotational transitions in real molecules are explored, using examples from CO + CO inelastic scattering
Addition of silicon improves oxidation resistance of nickel based superalloys
Specific weight changes of nickel-base superalloy B-1900 and B-1900 + 1% Si specimens were tested at 1273 K. B-1900 was losing weight at an increasing rate due to spalling of oxide scale while B-1900 + 1% Si was still gaining weight at low, nearly constant rate. Similar comparison in weight change was observed for specimens tested at 1373 K
Attitudes Toward Updated Genetic Testing Among Patients with Unexplained Mismatch Repair Deficiency
Individuals who have colorectal cancer (CRC) or endometrial cancer (EC) displaying loss of immunohistochemical (IHC) staining of one or more mismatch repair (MMR) proteins without a causative germline mutation are said to have unexplained mismatch repair deficiency (UMMRD, also known as mutation-negative Lynch syndrome). Comprehensive genetic testing that could potentially further clarify Lynch syndrome (LS) carrier status is essential to provide tailored screening guidelines to affected individuals and their family members; however, patient understanding of the potential impact of updated genetic testing for LS is unclear. This study aimed to evaluate the interest in and perceived impact of updated genetic testing among individuals with UMMRD at a tertiary academic center. A survey evaluating interest in updated genetic testing was mailed to 98 potential participants, and an electronic health record review was completed for the 31 individuals who returned the survey. Results indicate that this population is highly interested in updated genetic testing, and their perceived impact is primarily for family members to have appropriate testing and screening options. Updated risk assessment and genetic counseling, along with a discussion of the benefits and limitations of genetic testing, is essential as the understanding of potential causes of UMMRD evolves. Updated genetic counseling may allow patients with UMMRD to better understand the interpretation of their tumor and germline testing, as well as the impact of comprehensive genetic testing for themselves and their family members
Complex Philosophy
As science, knowledge, and ideas evolve and are increased and refined, the branches
of philosophy in charge of describing them should also be increased and refined. In this work
we try to expand some ideas as a response to the recent approach from several sciences to
complex systems. Because of their novelty, some of these ideas might require further
refinement and may seem unfinished, but we need to start with something. Only with their
propagation and feedback from critics they might be improved.
We make a brief introduction to complex systems, for then defining <em>abstraction levels</em>.
Abstraction levels represent simplicities and regularities in nature. We make an ontological
distinction of absolute being and relative being, and then discuss issues on causality,
metaphysics, and determinism
The De Rossett Farm (41HE75) and Quate Place (41HE81) Sites in the Cobb Creek Valley in the Upper Neches River Basin, Henderson County, Texas
The De Rossett Farm and Quate Place sites were among the earliest East Texas archaeological sites to be investigated by professional archaeologists at The University of Texas (UT), which began under the direction of Dr. J. E. Pearce between 1918-1920. According to Pearce, UT began work in this part of the state under the auspices of the Bureau of American Ethnology, and that work “had led me to suppose that I should find this part of the State rich in archeological material of a high order.”
The two sites were investigated in August 1920. They are on Cobb Creek, a small and eastward-flowing tributary to the Neches River, nor far to the northeast of the town of Frankston, Texas; the sites are across the valley from each other. The De Rossett Farm site is on an upland slope on the north side of the valley, while the Quate Place site is on an upland slope on the south side of the Cobb Creek valley, about 2 km west of the Neches River, and slightly southeast from the De Rossett Farm. Both sites have domestic Caddo archaeological deposits, and there was an ancestral Caddo cemetery of an unknown extent and character at the De Rossett Farm
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