Anharmonic quantum contribution to vibrational dephasing

Based on a quantum Langevin equation and its corresponding Hamiltonian within a c-number formalism we calculate the vibrational dephasing rate of a cubic oscillator. It is shown that leading order quantum correction due to anharmonicity of the potential makes a significant contribution to the rate and the frequency shift. We compare our theoretical estimates with those obtained from experiments for small diatomics $N_2$, $O_2$ and $CO$.Comment: 21 pages, 1 figure and 1 tabl

Defying Dementia: An Exploration of Recovery

Exploring the human side of dementia helps put a face on this fast-growing affliction. This study reflects one elderly woman’s story of recovery from dementia that arose following a stroke. Painting a portrait of life with dementia can help us conceptualize the experience, how people live and how they would like to live. The woman is Marcia, my mom, and this is a qualitative inquiry with a collaborative narrative design to explore her experiences and to document my own. This study may help dementia patients and their support teams better understand the process of living with dementia and can perhaps lead to a more informed and supportive environment to optimize recovery for all concerned

Evolutionary determination of experimental parameters for ptychographical imaging

The Ptychographical Iterative Engine (PIE) algorithm is a recently developed novel method of Coherent Diffractive Imaging (CDI) that uses multiple overlapping diffraction patterns to reconstruct an image. This method has successfully produced high quality reconstructions at both optical and X-ray wavelengths but the need for accurate knowledge of the probe positions is currently a limiting factor in the production of high resolution reconstructions at electron wavelengths. This paper examines the shape of the search landscape for producing optimal image reconstructions in the specific case of electron microscopy and then shows how evolutionary search methods can be used to reliably determine experimental parameters in the electron microscopy case (such as the spherical aberration in the probe and the probe positions)

Multiobjective synchronization of coupled systems

Copyright @ 2011 American Institute of PhysicsSynchronization of coupled chaotic systems has been a subject of great interest and importance, in theory but also various fields of application, such as secure communication and neuroscience. Recently, based on stability theory, synchronization of coupled chaotic systems by designing appropriate coupling has been widely investigated. However, almost all the available results have been focusing on ensuring the synchronization of coupled chaotic systems with as small coupling strengths as possible. In this contribution, we study multiobjective synchronization of coupled chaotic systems by considering two objectives in parallel, i. e., minimizing optimization of coupling strength and convergence speed. The coupling form and coupling strength are optimized by an improved multiobjective evolutionary approach. The constraints on the coupling form are also investigated by formulating the problem into a multiobjective constraint problem. We find that the proposed evolutionary method can outperform conventional adaptive strategy in several respects. The results presented in this paper can be extended into nonlinear time-series analysis, synchronization of complex networks and have various applications

Unexpected impact of D waves in low-energy neutral pion photoproduction from the proton and the extraction of multipoles

Contributions of $D$ waves to physical observables for neutral pion photoproduction from the proton in the near-threshold region are studied and means to isolate them are proposed. Various approaches to describe the multipoles are employed --a phenomenological one, a unitary one, and heavy baryon chiral perturbation theory. The results of these approaches are compared and found to yield essentially the same answers. $D$ waves are seen to enter together with $S$ waves in a way that any means which attempt to obtain the $E_{0+}$ multipole accurately must rely on knowledge of $D$ waves and that consequently the latter cannot be dismissed in analyses of low-energy pion photoproduction. It is shown that $D$ waves have a significant impact on double-polarization observables that can be measured. This importance of $D$ waves is due to the soft nature of the $S$ wave and is a direct consequence of chiral symmetry and the Nambu--Goldstone nature of the pion. $F$-wave contributions are shown to be negligible in the near-threshold region.Comment: 38 pages, 13 figures, 19 tables. Version to be published in Physical Review

A simple method for estimating the influence of eroding soil profiles on atmospheric CO2

This published article is © American Geophysical Union and can found on the publisher's website at http://dx.doi.org/10.1029/2009GB003560Although soil erosion has often been considered a net source of atmospheric carbon (C), several recent studies suggest that erosion serves as a net C sink. We have developed a spreadsheet‐based model of soil organic C dynamics within an eroding profile (Soil Organic Carbon, Erosion, Replacement, and Oxidation (SOrCERO)) that calculates effects of soil organic carbon (SOC) erosion and altered SOC oxidation and production on the net exchange of C between the eroding profile and atmosphere. SOrCERO suggests that erosion can induce a net C sink or source, depending on management practices, the extent to which SOC oxidation and production characteristics change with erosion, and the fate of eroded SOC. Varying these parameters generated a wide range of C source and sink estimates (maximum net source and sink of 1.1/3.1 Pg C yr−1 respectively, applying results globally), highlighting research needs to constrain model estimates. We invite others to download SOrCERO (http://www.kbs.ku.edu/people/staff_www/billings/index.html) to test conceptual models and eroding soil profiles of interest in a consistent, comparable fashion

Primary Small Bowel Liposarcoma (Atypical Lipomatous Tumour) with Myogenic Differentiation

Primary small intestinal liposarcomas originating in the small bowel are uncommon with a generally poor prognosis due to the advanced stage at the time of diagnosis. We describe a case of primary small bowel dedifferentiated liposarcoma presenting as a solid mass in the right iliac fossa. The current case is unusual as the tumour seemingly originated from the bowel and the well-differentiated component was seen extensively infiltrating the bowel wall including the small bowel submucosa

Mass Spectrometric Analysis of Ehrlichia chaffeensis Tandem Repeat Proteins Reveals Evidence of Phosphorylation and Absence of Glycosylation

Ehrlichia chaffeensis has a small subset of immunoreactive secreted, acidic (pI approximately 4), tandem repeat (TR)-containing proteins (TRPs), which exhibit abnormally large electrophoretic masses that have been associated with glycosylation of the TR domain.In this study, we examined the extent and nature of posttranslational modifications on the native TRP47 and TRP32 using mass spectrometry. Matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) demonstrated that the mass of native TRP47 (33,104.5 Da) and TRP32 (22,736.8 Da) were slightly larger (179- and 288-Da, respectively) than their predicted masses. The anomalous migration of native and recombinant TRP47, and the recombinant TR domain (C-terminal region) were normalized by 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) modification of negatively charged carboxylates to neutral amides. Exhaustive tandem mass spectrometric analysis (92% coverage) performed on trypsin and Asp-N digested native TRP47 identified peptides consistent with their predicted masses. Two TRP47 peptides not identified were located in the normally migrating amino (N)-terminal region of TRP47 and contained predicted phosphorylation sites (tyrosine and serine residues). Moreover, native TRP47 was immunoprecipitated from E. chaffeensis-infected cell lysate with anti-phosphotyrosine (anti-pTyr) antibody.TRP47 and TRP32 are not modified by glycans and the substantial net negative charge of the ehrlichial TRPs, and particularly the highly acidic TRs present within the ehrlichial TRPs, is responsible for larger-than-predicted masses. Furthermore, this study provides evidence that the N-terminal region of the TRP47 is tyrosine phosphorylated

The mercury photosensitized reaction of dimethyl ether

The mercury photosensitized reaction of dimethyl ether has been investigated at pressures between 28 and 500 mm and at temperatures between 25°C and 292°C. At 25°C the products consist almost entirely of hydrogen and 1,2-dimethoxyethane, and the initial step has been shown to be the abstraction of a hydrogen atom.At higher temperatures CH2O, CH4, C2H6 and probably CH3OC2H5 become important products. They are derived from the decomposition of the methoxy methyl radical followed by subsequent radical recombination reactions. Carbon monoxide is produced in the later stages from the decomposition of formaldehyde.By varying the light intensity and pressure it has been shown that ethane and dimethoxyethane are produced by second order recombination of methyl and methoxy methyl radicals respectively. The activation energies of the following reactions have been estimated: CH3+CH3OCH3→CH4+CH3OCH2 E=9.0 kcal. CH3OCH2→CH3+CH2O E=19 kcal., the only assumption being that methyl and methoxy methyl radicals recombine with zero activation energy