Low complexity method for large-scale self-consistent ab initio electronic-structure calculations without localization

A novel low complexity method to perform self-consistent electronic-structure calculations using the Kohn-Sham formalism of density functional theory is presented. Localization constraints are neither imposed nor required thereby allowing direct comparison with conventional cubically scaling algorithms. The method has, to date, the lowest complexity of any algorithm for an exact calculation. A simple one-dimensional model system is used to thoroughly test the numerical stability of the algorithm and results for a real physical system are also given

Empirical studies of upper atmospheric species

The first month of spin-scan ozone imaging (SOI) data (October 1981) was processed and compared with total ozone mapping spectrometer and ground based data. Short term variations in the ozone field have been revealed using animated sequences of SOI data. High correlations were observed between SOI ozone and upper tropospheric meteorological data. The relationship between ozone and temperature in the stratosphere was investigated by examining Nimbus 4 backscattered ultraviolet ozone and selective chopper radiometer temperature measurements as well as solar Nimbus 7 solar backscattered ultraviolet ozone and stratospheric and mesospheric sounder temperature measurements. Results from these ozone temperature studies were compared with calculations from theoretical 2-D models. All of the lims infrared monitor of the stratosphere data was processed at 10 pressure levels and correlations between various species have been performed. The Venus Atmospheric Drag model was modified taking into account recent investigations on the Venus thermosphere and the resulting model was considered for incorporation into the Venus International Reference Atmosphere

Insulin resistance for glucose metabolism in disused soleus muscle of mice

Results of this study on mice provide the first direct evidence of insulin resistance for glucose metabolism in skeletal muscle that has undergone a previous period of reduced muscle usage. This lack of responsiveness to insulin developed in one day and in the presence of hypoinsulinemia. Future studies will utilize the model of hindlimb immobilization to determine the causes of these changes

A spatio-temporal entropy-based approach for the analysis of cyber attacks (demo paper)

Computer networks are ubiquitous systems growing exponentially with a predicted 50 billion devices connected by 2050. This dramatically increases the potential attack surface of Internet networks. A key issue in cyber defense is to detect, categorize and identify these attacks, the way they are propagated and their potential impacts on the systems affected. The research presented in this paper models cyber attacks at large by considering the Internet as a complex system in which attacks are propagated over a network. We model an attack as a path from a source to a target, and where each attack is categorized according to its intention. We setup an experimental testbed with the concept of honeypot that evaluates the spatiotemporal distribution of these Internet attacks. The preliminary results show a series of patterns in space and time that illustrate the potential of the approach, and how cyber attacks can be categorized according to the concept and measure of entropy

Direct and Heterodyne Detection of Microwaves in a Metallic Single Wall Carbon Nanotube

This letter reports measurements of microwave (up to 4.5 GHz) detection in metallic single-walled carbon nanotubes. The measured voltage responsivity was found to be 114 V/W at 77K. We also demonstrated heterodyne detection at 1 GHz. The detection mechanism can be explained based on standard microwave detector theory and the nonlinearity of the DC IV-curve. We discuss the possible causes of this nonlinearity. While the frequency response is limited by circuit parasitics in this measurement, we discuss evidence that indicates that the effect is much faster and that applications of carbon nanotubes as terahertz detectors are feasible