Robust Simulation of a TaO Memristor Model

This work presents a continuous and differentiable approximation of a Tantalum oxide memristor model which is suited for robust numerical simulations in software. The original model was recently developed at Hewlett Packard labs on the basis of experiments carried out on a memristor manufactured in house. The Hewlett Packard model of the nano-scale device is accurate and may be taken as reference for a deep investigation of the capabilities of the memristor based on Tantalum oxide. However, the model contains discontinuous and piecewise differentiable functions respectively in state equation and Ohm's based law. Numerical integration of the differential algebraic equation set may be significantly facilitated under substitution of these functions with appropriate continuous and differentiable approximations. A detailed investigation of classes of possible continuous and differentiable kernels for the approximation of the discontinuous and piecewise differentiable functions in the original model led to the choice of near optimal candidates. The resulting continuous and differentiable DAE set captures accurately the dynamics of the original model, delivers well-behaved numerical solutions in software, and may be integrated into a commercially-available circuit simulator

On identifying the neutron star that was born in the supernova that placed 60Fe onto the Earth

Recently, 60Fe was found in the Earth crust formed in a nearby recent supernova (SN). If the distance to the SN and mass of the progenitor of that SN was known, then one could constrain SN models. Knowing the positions, proper motions, and distances of dozens of young nearby neutron stars, we can determine their past flight paths and possible kinematic origin. Once the birth place of a neutron star in a SN is found, we would have determined the distance of the SN and the mass of the SN progenitor star.Comment: refereed NPA5 conference proceedings, in pres

Deterministic networks for probabilistic computing

Neural-network models of high-level brain functions such as memory recall and reasoning often rely on the presence of stochasticity. The majority of these models assumes that each neuron in the functional network is equipped with its own private source of randomness, often in the form of uncorrelated external noise. However, both in vivo and in silico, the number of noise sources is limited due to space and bandwidth constraints. Hence, neurons in large networks usually need to share noise sources. Here, we show that the resulting shared-noise correlations can significantly impair the performance of stochastic network models. We demonstrate that this problem can be overcome by using deterministic recurrent neural networks as sources of uncorrelated noise, exploiting the decorrelating effect of inhibitory feedback. Consequently, even a single recurrent network of a few hundred neurons can serve as a natural noise source for large ensembles of functional networks, each comprising thousands of units. We successfully apply the proposed framework to a diverse set of binary-unit networks with different dimensionalities and entropies, as well as to a network reproducing handwritten digits with distinct predefined frequencies. Finally, we show that the same design transfers to functional networks of spiking neurons.Comment: 22 pages, 11 figure

On the Use of StorAge Selection Functions to Assess Time‐Variant Travel Times in Lakes

Funding Information ERC. Grant Number: GA 335910 VeWaPeer reviewedPublisher PD

Review and Analysis of an Energy Efficiency Incentive Program for Commercial Buildings

A program with 13 participants provided reimbursement for improvements to decrease energy use largely in commercial and not-for-profit buildings but also in two government buildings. Electricity and natural gas savings were determined by modeling the energy use by accounting for changes in weather for the 12 months previous to the improvements, and then predicting energy use for the 12 months immediately after the improvements using the same model. The threshold for verifiable energy savings resulting from building improvements was a maximum uncertainty of 50% at the 68% confidence level. Improvements involving original furnace or air conditioner replacement resulted in significant and verifiable reductions in energy use. Energy savings due to lighting improvements were verified for only one of seven buildings in which lighting was upgraded. Verifiable results were obtained in buildings with constant usage patterns, hours of operation, and equipment. Significant changes not related to weather, and improvements resulting in less than 10% savings of the total energy measured at the meter led to non-verifiable results. Other benefits of the program not related to energy cost savings included increasing illumination while maintaining the same electricity use, and improving comfort and noise reduction with additional insulation. The program was very successful in leveraging significant private investment for building improvements. In addition, the program inspired business owners to make further improvements voluntarily after the program ended and also increased interest in similar future programs

Contribution of capecitabine for therapy of patients with gastroesophageal cancer: an update of recent phase III results

Putao Cen, Eric D Tetzlaff, Jaffer A AjaniDepartment of Gastrointestinal Medical Oncology in the Division of Cancer Medicine at the University of Texas MD Anderson Cancer Center, Houston, TX, USABackground: Capecitabine, an orally administered fluoropyrimidines, is widely used in the treatment of multiple malignancies. It has been extensively evaluated in patients with gastroesophageal carcinoma. Since recent reviews have discussed phase I/II trials (Cancer 107:221–231, 2006; Drugs 67:601–610, 2007), we focus on the impact of the results of the most current phase III trials using capectiabine in the treatment of advanced gastroesophageal cancers, primarily in the first-line setting.Methods: To find published phase III trials, Medline was searched for English-language clinical trials published from 1996 through June 2007 along with relevant abstracts presented at the American Society of Clinical Oncology, and meetings of the European Cancer Conference and European Society of Medical Oncology. Only representative trials were chosen for this manuscript.Results: The most frequently investigated combinations are capecitabine with taxanes, platinols, and camptothecins. Recent results of a large phase III trial (REAL-2) in untreated patients with gastroesophageal cancer suggest that capecitabine is a non-inferior substitute for intravenous 5-fluorouracil. These results of REAL-2 trial are substantiated by a smaller phase III trial. Previous analysis of multiple trials had suggested that capecitabine, when combined in doses lower than 1250 mg/m2 twice daily, consistently resulted in lower frequency of Grade 3 or 4 toxic effects.Conclusions: Capecitabine provides much needed convenience to patients with gastroesophageal cancer. The recent data derived from two phase III trials confirm that capecitabine is a suitable substitute for intravenous 5-fluorouracil in patients whose swallowing is not greatly affected. Capecitabine remains a subject of further investigations in this group of patients with interest.Keywords: capecitabine, gastroesophageal cancer, oral fluoropyrimidine