Computerized analytical technique for design and analysis of a Sabatier reactor subsystem Final engineering report

Mathematical model for computerized evaluation of Sabatier reaction kinetics in oxygen recovery from carbon dioxid

Temperature-dependent dynamical nuclear polarization bistabilities in double quantum dots in the spin-blockade regime

The interplay of dynamical nuclear polarization (DNP) and leakage current through a double quantum dot in the spin-blockade regime is analyzed. A finite DNP is built up due to a competition between hyperfine (HF) spin-flip transitions and another inelastic escape mechanism from the triplets, which block transport. We focus on the temperature dependence of the DNP for zero energy-detuning (i.e. equal electrostatic energy of one electron in each dot and a singlet in the right dot). Our main result is the existence of a transition temperature, below which the DNP is bistable, so a hysteretic leakage current versus external magnetic field B appears. This is studied in two cases: (i) Close to the crossing of the three triplet energy levels near B=0, where spin-blockade is lifted due to the inhomogeneity of the effective magnetic field from the nuclei. (ii) At higher B-fields, where the two spin-polarized triplets simultaneously cross two different singlet energy levels. We develop simplified models leading to different transition temperatures T_TT and T_ST for the crossing of the triplet levels and the singlet-triplet level crossings, respectively. We find T_TT analytically to be given solely by the HF couplings, whereas T_ST depends on various parameters and T_ST>T_TT. The key idea behind the existence of the transition temperatures at zero energy-detuning is the suppression of energy absorption compared to emission in the inelastic HF transitions. Finally, by comparing the rate equation results with Monte Carlo simulations, we discuss the importance of having both HF interaction and another escape mechanism from the triplets to induce a finite DNP.Comment: 26 pages, 17 figure

Electron-electron interaction effects in quantum point contacts

We consider electron-electron interaction effects in quantum point contacts on the first quantization plateau, taking into account all scattering processes. We compute the low-temperature linear and nonlinear conductance, shot noise, and thermopower, by perturbation theory and a self-consistent nonperturbative method. On the conductance plateau, the low-temperature corrections are solely due to momentum-nonconserving processes that change the relative number of left- and right-moving electrons. This leads to a suppression of the conductance for increasing temperature or voltage. The size of the suppression is estimated for a realistic saddle-point potential, and is largest in the beginning of the conductance plateau. For large magnetic field, interaction effects are strongly suppressed by the Pauli principle, and hence the first spin-split conductance plateau has a much weaker interaction correction. For the nonperturbative calculations, we use a self-consistent nonequilibrium Green's function approach, which suggests that the conductance saturates at elevated temperatures. These results are consistent with many experimental observations related to the so-called 0.7 anomaly

Soybeans as a home-grown supplement for dairy cows

Soybeans, grown on the farm, give promise of providing many dairymen with a valuable protein supplement for their dairy herds which will make them independent of the purchase of high-priced protein feeds. Investigations at the Iowa Agricultural Experiment Station show that soybeans make a palatable dairy feed, that they give good results in milk production when fed in place of other protein supplements, and that pound for pound they are a third more valuable than oilmeal, with which direct comparison was made. A home-grown supplement of that kind would be especially valuable to Iowa dairy farms. These farms easily produce all of the roughages needed for the herds in both winter and summer, such as ensilage, clover, alfalfa hay and soiling crops. It is also relatively easy for them to provide the greater portion of the grain ration, as the home-grown corn and oats should form the basis of the concentrates fed. These two feeds, however, are relatively low in protein and so are the roughages, with the exception of the legume hays. It is necessary, therefore, to secure additional concentrates which will provide the extra protein needed, especially in the ration of heavy producing cows. This is one of the main problems of dairy farming today

Ab initio vibrations in nonequilibrium nanowires

We review recent results on electronic and thermal transport in two different quasi one-dimensional systems: Silicon nanowires (SiNW) and atomic gold chains. For SiNW's we compute the ballistic electronic and thermal transport properties on equal footing, allowing us to make quantitative predictions for the thermoelectric properties, while for the atomic gold chains we evaluate microscopically the damping of the vibrations, due to the coupling of the chain atoms to the modes in the bulk contacts. Both approaches are based on a combination of density-functional theory, and nonequilibrium Green's functions.Comment: 16 pages, to appear in Progress in Nonequilibrium Green's Functions IV (PNGF4), Eds. M. Bonitz and K. Baltzer, Glasgow, August 200

When to Suspect Hidden Hypercortisolism in Type 2 Diabetes: A Meta-Analysis

Objective: To investigate whether the available literature helps to identify the characteristics of patients with type 2 diabetes (T2D) more frequently associated with hidden hypercortisolism (HidHyCo). Methods: A meta-analysis was performed using studies that assessed both the prevalence of HidHyCo in patients with T2D and the characteristics of these patients with and without HidHyCo. The DerSimonian and Laird (DSL) and Hartung-Knapp-Sidik-Jonkman (HKSJ) methods were utilized. Results: Among the 18 available studies, 6 provided the necessary data. The association between HidHyCo and advanced T2D (based on the patients’ description given in each study in the presence of microvascular/macrovascular complications or insulin treatment plus hypertension or hypertension treated with 2 or more drugs), hypertension, insulin treatment, and dyslipidemia was reported in 5 (2184 patients), 6 (2283 patients), 3 (1440 patients), and 3 (987 patients) studies, respectively. HidHyCo was associated with advanced T2D as assessed by both the DSL (odds ratio [OR], 3.4; 95% confidence interval [95% CI], 2.12-5.67) and HKSJ (OR, 3.60; 95% CI, 2.03-6.41) methods and with the prevalence of hypertension or insulin treatment as assessed by the DSL method (OR, 1.92; 95% CI, 1.05-3.50 and OR, 2.29; 95% CI, 1.07-4.91, respectively) but not as assessed by the HKSJ method. Conclusion: Patients with advanced T2D have a higher prevalence of HidHyCo. These data inform about the selection of patients with T2D for HidHyCo screening

Three-particle collisions in quantum wires: Corrections to thermopower and conductance

We consider the effect of electron-electron interaction on the electron transport through a finite length single-mode quantum wire with reflectionless contacts. The two-particle scattering events cannot alter the electric current and therefore we study the effect of three-particle collisions. Within the Boltzmann equation framework, we calculate corrections to the thermopower and conductance to the leading order in the interaction and in the length of wire $L$. We check explicitly that the three-particle collision rate is identically zero in the case of several integrable interaction potentials. In the general (non-integrable) case, we find a positive contribution to the thermopower to leading order in $L$. The processes giving rise to the correction involve electron states deep in the Fermi sea. Therefore the correction follows an activation law with the characteristic energy of the order of the Fermi energy for the electrons in the wire.Comment: 13 pages, 4 figure

Molecular basis of FIR-mediated c-myc transcriptional control

The far upstream element (FUSE) regulatory system promotes a peak in the concentration of c-Myc during cell cycle. First, the FBP transcriptional activator binds to the FUSE DNA element upstream of the c-myc promoter. Then, FBP recruits its specific repressor (FIR), which acts as an on/off transcriptional switch. Here we describe the molecular basis of FIR recruitment, showing that the tandem RNA recognition motifs of FIR provide a platform for independent FUSE DNA and FBP protein binding and explaining the structural basis of the reversibility of the FBP-FIR interaction. We also show that the physical coupling between FBP and FIR is modulated by a flexible linker positioned sequentially to the recruiting element. Our data explain how the FUSE system precisely regulates c-myc transcription and suggest that a small change in FBP-FIR affinity leads to a substantial effect on c-Myc concentration.MRC Grant-in-aid U11757455

Legumain in acute coronary syndromes: A substudy of the PLATO (Platelet Inhibition and Patient Outcomes) trial

Background The cysteine protease legumain is increased in patients with atherosclerosis, but its causal role in atherogenesis and cardiovascular disease is still unclear. The aim of the study was to investigate the association of legumain with clinical outcome in a large cohort of patients with acute coronary syndrome. Methods and Results Serum levels of legumain were analyzed in 4883 patients with acute coronary syndrome from a substudy of the PLATO (Platelet Inhibition and Patient Outcomes) trial. Levels were analyzed at admission and after 1 month follow‐up. Associations between legumain and a composite of cardiovascular death, spontaneous myocardial infarction or stroke, and its individual components were assessed by multivariable Cox regression analyses. At baseline, a 50% increase in legumain level was associated with a hazard ratio (HR) of 1.13 (95% CI, 1.04–1.21), P=0.0018, for the primary composite end point, adjusted for randomized treatment. The association remained significant after adjustment for important clinical and demographic variables (HR, 1.10; 95% CI, 1.02–1.19; P=0.013) but not in the fully adjusted model. Legumain levels at 1 month were not associated with the composite end point but were negatively associated with stroke (HR, 0.62; 95% CI, 0.44–0.88; P=0.0069), including in the fully adjusted model (HR, 0.57; 95% CI, 0.37–0.88; P=0.0114). Conclusions Baseline legumain was associated with the primary outcome in patients with acute coronary syndrome, but not in the fully adjusted model. The association between high levels of legumain at 1 month and decreased occurrence of stroke could be of interest from a mechanistic point of view, illustrating the potential dual role of legumain during atherogenesis and acute coronary syndrome. Registration URL: https://www.clini​caltr​ials.gov; Unique identifier: NCT00391872