Recycling random numbers in the stochastic simulation algorithm

The stochastic simulation algorithm (SSA) was introduced by Gillespie and in a different form by Kurtz. Since its original formulation there have been several attempts at improving the efficiency and hence the speed of the algorithm. We briefly discuss some of these methods before outlining our own simple improvement, the recycling direct method (RDM), and demonstrating that it is capable of increasing the speed of most stochastic simulations. The RDM involves the statistically acceptable recycling of random numbers in order to reduce the computational cost associated with their generation and is compatible with several of the pre-existing improvements on the original SSA. Our improvement is also sufficiently simple (one additional line of code) that we hope will be adopted by both trained mathematical modelers and experimentalists wishing to simulate their model systems

Effects of Process Variables and Size Scale on Solidification Microstructure in Laser-Based Solid Freeform Fabrication of Ti-6Al-4V

Mechanical Engineerin

Sensor Fusion Algorithm and Calibration for a Gyroscope-free IMU

AbstractThis paper presents a gyroscope-free inertial measurement unit (IMU) that only consists of linear acceleration sensors. Only a simple matrix multiplication has to be performed in order to calculate the complete relative movement of a body. However, the precise positions and orientations of the sensors within the body frame have to be known in order to calculate the exact movement of the body. A simple and effective calibration algorithm developed in this paper can be applied to determine these parameters entirely even without any previous knowledge. Measurements on a 3D-rotation table were carried out to demonstrate the accuracy improvements after the calibration. Thereby, the RMS error of the angular rate was reduced by a factor of 2.8

Resolution of diaschisis contributes to early recovery from post-stroke aphasia

Diaschisis is a phenomenon observed in stroke that is defined as neuronal dysfunction in regions spared by the infarction but connected to the lesion site. We combined lesion network mapping and task-based functional MRI in 71 patients with post-stroke aphasia to investigate, whether diaschisis and its resolution contribute to early loss and recovery of language functions. Language activation acquired in the acute, subacute and chronic phase was analyzed in compartments with high and low normative resting-state functional connectivity to the lesion site on an individual basis. Regions with high compared to regions with low lesion connectivity showed a steeper increase in language reactivation from the acute to the subacute phase. This finding is compatible with the assumption of resolution of diaschisis. Additionally, language performance in the subacute phase and improvement from the subacute to the chronic phase significantly correlated with the diaschisis effect and its resolution, respectively, suggesting a behavioral relevance of this effect. We therefore assume that undamaged but functionally connected regions become dysfunctional due to missing input from the lesion contributing to the aphasic deficit. Since these regions are structurally intact, dysfunction resolves over time contributing to the rapid early behavioral improvement observed in aphasic stroke patients. Our results demonstrate that diaschisis and its resolution might be a relevant mechanism of early loss and recovery of language function in acute stroke patients

Evaluation of an Intimate Partner Violence Curriculum in a Pediatric Hospital

OBJECTIVE. Intimate partner violence harms victims as well as families and communities. Many barriers account for limited intimate partner violence screening by nurses. The purpose of this study was to measure how participation in a curriculum about screening parents for intimate partner violence, at a pediatric hospital, affects a nurse\u27s knowledge, attitudes, behaviors, and self-efficacy for intimate partner violence screening. METHODS. In this interventional, longitudinal study, data were collected before participation in an intimate partner violence screening curriculum, after participation, and 3 months later. The measurement tool was adapted from Maiuro\u27s (2000) Self-efficacy for Screening for Intimate Partner Violence Questionnaire. RESULTS. Sixty-eight pediatric nurses completed all aspects of the study. At baseline, 18 (27%) nurses self-reported seeing a parent with an injury, and of those only 7 (39%) followed up with intimate partner violence screening. Factor analysis was performed on the baseline Self-efficacy for Screening for Intimate Partner Violence Questionnaire by using varimax rotation. Five factors were identified: conflict, fear of offending parent, self-confidence, appropriateness, and attitude. Only fear of offending parent was significantly different from times 1 to 3, indicating that nurses were less fearful after the training. Cronbach\u27s α value for the total questionnaire at baseline was .85. Nurses reported significant improvement (baseline to 3-month follow-up) in several self-efficacy items. CONCLUSIONS. Participation in a 30-minute curriculum on intimate partner violence screening was associated with improvements in self-efficacy and significantly lower fear of offending parents 3 months after training. Nurses also showed improvement in the perception of resources available for nurses to manage intimate partner violence. Thirty-minute hospital-based curriculums that include victim testimonial video and practice role-playing to simulate parent interactions are recommended

Interactive impacts of meteorological and hydrological conditions on the physical and biogeochemical structure of a coastal system

The German Bight was exposed to record high riverine discharges in June 2013, as a result of flooding of the Elbe and Weser rivers. Several anomalous observations suggested that the hydrodynamical and biogeochemical states of the system were impacted by this event. In this study, we developed a biogeochemical model and coupled it with a previously introduced high-resolution hydrodynamical model of the southern North Sea in order to better characterize these impacts and gain insight into the underlying processes. Performance of the model was assessed using an extensive set of in situ measurements for the period 2011–2014. We first improved the realism of the hydrodynamic model with regard to the representation of cross-shore gradients, mainly through inclusion of flow-dependent horizontal mixing. Among other characteristic features of the system, the coupled model system can reproduce the low salinities, high nutrient concentrations and low oxygen concentrations in the bottom layers observed within the German Bight following the flood event. Through a scenario analysis, we examined the sensitivity of the patterns observed during July 2013 to the hydrological and meteorological forcing in isolation. Within the region of freshwater influence (ROFI) of the Elbe–Weser rivers, the flood event clearly dominated the changes in salinity and nutrient concentrations, as expected. However, our findings point to the relevance of the peculiarities in the meteorological conditions in 2013 as well: a combination of low wind speeds, warm air temperatures and cold bottom-water temperatures resulted in a strong thermal stratification in the outer regions and limited vertical nutrient transport to the surface layers. Within the central region, the thermal and haline dynamics interactively resulted in an intense density stratification. This intense stratification, in turn, led to enhanced primary production within the central region enriched by nutrients due to the flood but led to reduction within the nutrient-limited outer region, and it caused a widespread oxygen depletion in bottom waters. Our results further point to the enhancement of the current velocities at the surface as a result of haline stratification and to intensification of the thermohaline estuarine-like circulation in the Wadden Sea, both driven by the flood event

Allosteric inhibition of carnosinase (CN1) by inducing a conformational shift

In humans, low serum carnosinase (CN1) activity protects patients with type 2 diabetes from diabetic nephropathy. We now characterized the interaction of thiol-containing compounds with CN1 cysteine residue at position 102, which is important for CN1 activity. Reduced glutathione (GSH), N-acetylcysteine and cysteine (3.2 \uc2\ub1 0.4, 2.0 \uc2\ub1 0.3, 1.6 \uc2\ub1 0.2 \uc2\ub5mol/mg/h/mM; p <.05) lowered dose-dependently recombinant CN1 (rCN1) efficiency (5.2 \uc2\ub1 0.2 \uc2\ub5mol/mg/h/mM) and normalized increased CN1 activity renal tissue samples of diabetic mice. Inhibition was allosteric. Substitution of rCN1 cysteine residues at position 102 (Mut1C102S) and 229 (Mut2C229S) revealed that only cysteine-102 is influenced by cysteinylation. Molecular dynamic simulation confirmed a conformational rearrangement of negatively charged residues surrounding the zinc ions causing a partial shift of the carnosine ammonium head and resulting in a less effective pose of the substrate within the catalytic cavity and decreased activity. Cysteine-compounds influence the dynamic behaviour of CN1 and therefore present a promising option for the treatment of diabetes