Average transmission probability of a random stack

The transmission through a stack of identical slabs that are separated by gaps with random widths is usually treated by calculating the average of the logarithm of the transmission probability. We show how to calculate the average of the transmission probability itself with the aid of a recurrence relation and derive analytical upper and lower bounds. The upper bound, when used as an approximation for the transmission probability, is unreasonably good and we conjecture that it is asymptotically exact.Comment: 10 pages, 6 figure

Mild and General Conditions for Negishi Cross-Coupling Enabled by the Use of Palladacycle Precatalysts

A wide range of biaryls were synthesized by palladium-catalyzed Negishi cross-couplings at ambient temperature or with low catalyst loading. This protocol features the use of a recently reported aminobiphenyl palladacycle precatalyst to generate the catalytically active XPhosPd[superscript 0] species. Significantly, a wide range of challenging heterocyclic and polyfluorinated aromatic substrates can be employed to give products in excellent yields.National Institutes of Health (U.S.) (GM46059

Atom chips on direct bonded copper substrates

We present the use of direct bonded copper (DBC) for the straightforward fabrication of high power atom chips. Atom chips using DBC have several benefits: excellent copper/substrate adhesion, high purity, thick (> 100 microns) copper layers, high substrate thermal conductivity, high aspect ratio wires, the potential for rapid (< 8 hr) fabrication, and three dimensional atom chip structures. Two mask options for DBC atom chip fabrication are presented, as well as two methods for etching wire patterns into the copper layer. The wire aspect ratio that optimizes the magnetic field gradient as a function of power dissipation is determined to be 0.84:1 (height:width). The optimal wire thickness as a function of magnetic trapping height is also determined. A test chip, able to support 100 A of current for 2 s without failing, is used to determine the thermal impedance of the DBC. An assembly using two DBC atom chips to provide magnetic confinement is also shown.Comment: 8 pages, 5 figure

Saying Hello World with GReTL - A Solution to the TTC 2011 Instructive Case

This paper discusses the GReTL solution of the TTC 2011 Hello World case. The submitted solution covers all tasks including the optional ones.Comment: In Proceedings TTC 2011, arXiv:1111.440

S.O.S.

The concept that type 2 diabetes mellitus (T2DM) can be reversed with an intestinal operation is counterintuitive. How could our costliest disease be forced into full, durable, and safe remission with the bypass of a few inches of intestine? Counterintuitive or not, it’s true. Accordingly, we take notice when Sjöström and colleagues (1) in the Swedish Obese Subjects (SOS) study, the longest and most complete bariatric surgery outcome study in the world, document in this issue that bariatric surgery reduces the incidence of heart attacks. The SOS is a prospective, nonrandomized, controlled interventional trial on the effect of bariatric surgery on mortality and morbidity compared with conventional treatment that enrolled 4,047 obese individuals from 1 September 1987 to 31 January 2001. Of these, 2,010 underwent bariatric surgery, and a contemporary matched group of 2,037 did not. The current report compared the 345 diabetic patients who underwent bariatric surgery with the 262 who did not. The authors found that “bariatric surgery was associated with a reduced myocardial infarction incidence� (38/345 [11.0%] in the surgery vs. control group 43/262 [16.4%] [P = 0.017]). The effect was stronger in individuals with higher serum cholesterol and triglycerides at baseline. Not surprising, since the bariatric surgery was associated with significant decreases in body weight, blood glucose, serum triglycerides, systolic and diastolic blood pressure, and an increase in HDL-cholesterol

Adjustable microchip ring trap for cold atoms and molecules

We describe the design and function of a circular magnetic waveguide produced from wires on a microchip for atom interferometry using deBroglie waves. The guide is a two-dimensional magnetic minimum for trapping weak-field seeking states of atoms or molecules with a magnetic dipole moment. The design consists of seven circular wires sharing a common radius. We describe the design, the time-dependent currents of the wires and show that it is possible to form a circular waveguide with adjustable height and gradient while minimizing perturbation resulting from leads or wire crossings. This maximal area geometry is suited for rotation sensing with atom interferometry via the Sagnac effect using either cold atoms, molecules and Bose-condensed systems

Model-based myocardial T1 mapping with sparsity constraints using single-shot inversion-recovery radial FLASH cardiovascular magnetic resonance.

BACKGROUND: This study develops a model-based myocardial T1 mapping technique with sparsity constraints which employs a single-shot inversion-recovery (IR) radial fast low angle shot (FLASH) cardiovascular magnetic resonance (CMR) acquisition. The method should offer high resolution, accuracy, precision and reproducibility. METHODS: The proposed reconstruction estimates myocardial parameter maps directly from undersampled k-space which is continuously measured by IR radial FLASH with a 4 s breathhold and retrospectively sorted based on a cardiac trigger signal. Joint sparsity constraints are imposed on the parameter maps to further improve T1 precision. Validations involved studies of an experimental phantom and 8 healthy adult subjects. RESULTS: In comparison to an IR spin-echo reference method, phantom experiments with T1 values ranging from 300 to 1500 ms revealed good accuracy and precision at simulated heart rates between 40 and 100 bpm. In vivo T1 maps achieved better precision and qualitatively better preservation of image features for the proposed method than a real-time CMR approach followed by pixelwise fitting. Apart from good inter-observer reproducibility (0.6% of the mean), in vivo results confirmed good intra-subject reproducibility (1.05% of the mean for intra-scan and 1.17, 1.51% of the means for the two inter-scans, respectively) of the proposed method. CONCLUSION: Model-based reconstructions with sparsity constraints allow for single-shot myocardial T1 maps with high spatial resolution, accuracy, precision and reproducibility within a 4 s breathhold. Clinical trials are warranted

Absence of a consistent classical equation of motion for a mass-renormalized point charge

The restrictions of analyticity, relativistic (Born) rigidity, and negligible O(a) terms involved in the evaluation of the self electromagnetic force on an extended charged sphere of radius "a" are explicitly revealed and taken into account in order to obtain a classical equation of motion of the extended charge that is both causal and conserves momentum-energy. Because the power-series expansion used in the evaluation of the self force becomes invalid during transition time intervals immediately following the application and termination of an otherwise analytic externally applied force, transition forces must be included during these transition time intervals to remove the noncausal pre-acceleration and pre-deceleration from the solutions to the equation of motion without the transition forces. For the extended charged sphere, the transition forces can be chosen to maintain conservation of momentum-energy in the causal solutions to the equation of motion within the restrictions of relativistic rigidity and negligible O(a) terms under which the equation of motion is derived. However, it is shown that renormalization of the electrostatic mass to a finite value as the radius of the charge approaches zero introduces a violation of momentum-energy conservation into the causal solutions to the equation of motion of the point charge if the magnitude of the external force becomes too large. That is, the causal classical equation of motion of a point charge with renormalized mass experiences a high acceleration catastrophe.Comment: 13 pages, No figure

Survey of Services for Adult Students and Faculty at the University Center at Tulsa

This study was focused on three major areas: (1) a study of the adult college students' utilization of existing student services and the usefulness of these services; (2) a study of the services needed, but currently not provided, and (3) a study of the faculty's perception of needs and usefulness of the sertices. The main objective was to research the students and faculty for needs data which can be used to assist in resolution of problems and development of an effective learning environment for students and faculty at the University Center at Tulsa (UCT).Occupational and Adult Educatio

Isotopic constraints on nitrogen transformation rates in the deep sedimentary marine biosphere

Author Posting. © American Geophysical Union,2018. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Isotopic constraints on nitrogen transformation rates in the deep sedimentary marine biosphere. Global Biogeochemical Cycles, 32, (2018):1688–1702., doi: 10.1029/2018GB005948.Little is known about the nature of microbial community activity contributing to the cycling of nitrogen in organic-poor sediments underlying the expansive oligotrophic ocean gyres. Here we use pore water concentrations and stable N and O isotope measurements of nitrate and nitrite to constrain rates of nitrogen cycling processes over a 34-m profile from the deep North Atlantic spanning fully oxic to anoxic conditions. Using a 1-D reaction-diffusion model to predict the distribution of nitrogen cycling rates, results converge on two distinct scenarios: (1) an exceptionally high degree of coupling between nitrite oxidation and nitrate reduction near the top of the anoxic zone or (2) an unusually large N isotope effect (~60‰) for nitrate reduction that is decoupled from the corresponding O isotope effect, which is possibly explained by enzyme-level interconversion between nitrite and nitrate.Samples analyzed for this study were collected during the final expedition of the RV Knorr, KN223. The expedition would not have been possible without the captain and crew of the RV Knorr and the efforts of the shipboard science party. We would like to acknowledge Robert Pockalny for planning and facilitating the expedition. Inorganic geochemistry sample collection, processing, and analysis were performed shipboard by Arthur Spivack,Dennis Graham, Chloe Anderson, Emily Estes, Kira Homola, Claire McKinley, Theodore Present, and Justine Sauvage. Coring capabilities were provided by the Oregon State University and Woods Hole Oceanographic Institute Coring Facilities, directed and funded by the U. S. National Science Foundation (NSF) Ship Facilities Program. The cored materials and discrete samples from the expedition are curated and stored by the Marine Geological Samples Laboratory at the University of Rhode Island, codirected by Rebecca Robinson and Katherine Kelly and funded by the NSF Ocean Sciences Division. The nutrient and isotope data from pore waters in this study will be available at The Biological and Chemical Data Management Office (https://www.bcodmo.org/project/567401). This project was partially funded by an NSF CDEBI postdoctoral fellowship to C. Buchwald. Portions of this material are based upon work supported while R. W. M. was serving at the National Science Foundation.2019-04-1