Geometrical codification for clustering mixed categorical and numerical databases

This paper presents an alternative to cluster mixed databases. The main idea is to propose a general method to cluster mixed data sets, which is not very complex and still can reach similar levels of performance of some good algorithms. The proposed approach is based on codifying the categorical attributes and use a numerical clustering algorithm on the resulting database. The codification proposed is based on polar or spherical coordinates, it is easy to understand and to apply, the increment in the length of the input matrix is not excessively large, and the codification error can be determined for each case. The proposed codification combined with the well known k-means algorithm showed a very good performance in different benchmarks and has been compared with both, other codifications and other mixed clustering algorithms, showing a better or comparable performance in all cases.     

Superconducting Sphere and Finite-Size Permanent Magnet: Force, Torque, and Alignment Effect Calculation

Using a local first-order interaction model, previously described, the force and torque between a superconducting sphere in the Meissner state and a finite-size permanent magnet are calculated. These findings are compared to results obtained by other models for the force based on the images method for a point magnetic dipole. It is demonstrated that the first-order calculation is a good approximation. Moreover, the torque between a superconducting sphere and a magnet in different positions and angular orientations is calculated for the first time. We describe the alignment effect that tends to align a magnet tangentially to the superconducting sphere surface. In addition, it is shown that the finiteness of the magnet reduces the magnitude of the repulsive force.     

Integrated Assessment of the European WFD Implementation in Extremely Overexploited Aquifers Through Participatory Modelling

Participatory methods provide an increasingly accepted path to integrated water assessment. This research describes an interdisciplinary exercise of scenario design and modelling, which provides a methodology to couple hard science numerical modelling approaches with the involvement of key water actors and socioeconomic issues. A decision support system based on probabilistic methods (Bayesian networks) is the tool chosen for dealing with the interdisciplinary issues involved in this aquifer. Given the long-standing conflicts in the area, modelling work largely focuses on carrying out an impact assessment produced by different scenarios established under the light of the mandatory objectives established by the European Union Water Framework Directive. This methodology is applied to a semi-arid aquifer located in SE Spain (Serral-Salinas) that represents an extreme case of intensive groundwater use. Irrigation has been a catalyst for welfare in the area for the past 40?years, despite the resulting large groundwater drawdown and continuous rise of groundwater pumping energy costs. Modelling results suggest that only a drastic change in the abstraction regime can produce a solution to long term sustainability of the aquifers. In addition, the impact assessment advises that such objectives are unlikely to be met due to the high economic costs of this action.     

Constructing a useful tool for characterizing amino acid conformers by means of quantum chemical and graph theory indices

The aim of this work is to construct a tool to assist in the prediction of peptidic properties resulting from the exchange of two amino acids in a proteic chain. In the past others have used experimental properties for this purpose. However, the nature of these data sets severely limits their access to important properties pertaining to secondary structure, and hence the indices used cannot characterize different backbone conformers like alpha helix and beta strands, or side-chain conformations like gauche +, gauche - and trans. In this study we explore the importance of backbone and side-chain angles with regard to conformer similarity measured with theoretical properties calculated in an ab initio manner. For each of the 20 genetically encoded amino acids, we studied five conformers that correspond to alpha helical and beta strand structures, with three different side chain conformations for each, defined solely by their angles phi, psi and chi1. This methodology allowed each of the 108 conformers to be represented by a mathematical object without ambiguity. The peptidic chain was emulated using two capping models to simulate the effect of nearest neighbors. These are OHC-Xaa-NH2 and Ala-Xaa-Ala, where Xaa is the conformer of interest. We then calculated 40 ab initio quantum chemical and graph theory indices for each backbone-side-chain conformer to obtain a characterization and classification scheme. We found that: (1) while backbone structure is very important to conformer similarity, side-chain conformations do not cluster together in a top-level manner; (2) amino acids with pi electrons group together independent of backbone conformation.     

Germicidal UV Sensitivity of Bacteria in Aerosols and on Contaminated Surfaces

We compared the UV sensitivity of Bacillus atrophaeus (a surrogate for B. anthracis), Pantoea agglomerans (a bacterial simulant frequently used in biodefense studies), and Yersinia ruckeri (a surrogate for Yersinia pestis) either airborne or deposited on a semisolid (wet) agar surface. Bacterial vegetative cells were aerosolized into an exposure chamber and exposed for various lengths of time to an ultraviolet (UV) light source emitting at 254 nanometer (nm) (in the UVC region also known as UVGI). Aerosols were collected onto gelatin filters, which were dissolved, diluted, plated, and incubated to enumerate colony formation. In darkness (with the UV light switched off), it took between 170 and 330 s airborne (depending on the bacterial species) to decrease by 90% of the original load (i.e., by 1 Log₁₀) the number of viable organisms originally present. The fluence of UVC required to inactivate 90% (F_{–1 Log10}) of bacteria aerosolized into an atmosphere with 80–90% relative humidity corresponded to 70.3 J.m^?2, 73.3 J.m^?2 and 18.3 J.m^?2 for vegetative cells of B. atrophaeus, P. agglomerans, and Y. ruckeri cells, respectively. Additionally, the UV sensitivity of bacteria deposited directly on agar nutrient plates was determined after exposure to 254-nm UV with the F_–1Log10 for the same bacteria on surfaces corresponding to 128 J.m^?2, 28.1 J.m^?2, and 16.3 J.m^?2, respectively. These comparative results among different bacterial species, either airborne or on contaminated surfaces, should assist in predicting the survival of bacterial cells after transmission from infected patients or after an intentional release into the environment.     

On the Use of AMl and PM3 Methods on Energetic Compounds

Stewart's new semi-empirical method MNDO-PM3 (PM3) is compared with the well known Dewar's AMl method in the study of nitrosubstituted compounds, and some energetic materials. PM3 method shows better performances than the AMl one. Adjacent lone pair/lone pair repulsion are better described at PM3 level and the known systematic correction of about −9 kcal/mol for each C-NO₂ group of the AMl method becomes +3.5 kcal/mol at PM3 level. PM3 results for N-NO₂ containing compounds are directly comparable with experimental gas phase data.     

Structure and Tautomerism of ANTA (aminonitrotriazole)

Energy and dipole moment calculations show 3-nitro-5- amino-1,2,4-triazole is the most stable tautomer of ANTA either in the gas phase and polar solvents, in agreement with X-ray findings. Our calculations predict that the 5-nitro-3-amino-1,2,4-triazole tautomer is more sensitive to shock or impact. Some discrepancies between semiempirical (AMI and PM3) calculations and ab initio (up to 6-31G*//6-31G) are studied.     

Method to Determine the Number of Bacterial Spores Within Aerosol Particles

We describe methodology to reveal the number of microbial spores within aerosol particles. The procedure involves visualization under differential- interference-contrast microscopy enhanced by high-resolution photography and further analysis by computer-assisted imaging. The method was used to analyze spore of Bacillus globigii in aerosols generated by a small (pressured metered-dose inhaler type) generator. Particles consisting in 1 or 2 spores accounted for 85% of all generated particles. This percentage rose to 91% when the same aerosol was collected on an Andersen cascade impactor that collected particles larger than 0.65 μm and was even higher (96%) when particles larger than 3.3 μm were also eliminated. These results demonstrate that the imaging analysis of aerosol particles collected on glass slides is sensitive to even relatively small changes in aerosol particle composition. The accuracy of the enhanced microscopic method described herein (differences between visual and computer analysis were approximately 3% of the total particle counts) seems adequate to determine the spore composition of aerosols of interest in biodefense.     

Activated carbon cloth as support for mesenchymal stem cell growth and differentiation to osteocytes

Activated carbon cloth was shown to be a good support for the growth and differentiation of mesenchymal stem cells (MSCs). By using this approach, we improved the cell culture procedure and reduced the laboratory time required to obtain a very large number of MSCs suitable for utilization or differentiation.     

COINS: COalitions and INcentiveS for effective Peer-to-Peer downloads

Although the proportion of Peer-to-Peer (P2P) traffic has declined in recent years in favor of video streaming and one-click hosting, P2P traffic is predicted to increase in the years to come. Moreover, P2P principles can be applied to improve both, video streaming and one-click hosting, so, P2P is going to continue to be an active research area. This paper presents COINS, a new coalition-formation and incentive mechanism based on game theory. This mechanism encourages cooperative behavior, since contributing peers receive in return a better quality of service, whilst preventing the free-riding problem. To achieve this, we define a “Responsiveness bonus” that reflects the overall contribution of the peer to the system, and we use the game theory utility concept to calculate it. Empirical results, obtained through simulations, show the ability of the coalitions to effectively stop free-riding and promote contribution, increasing the performance of the P2P network and obtaining an improvement in download time. In addition, we prove that users that pursue self-interested strategies, and that contribute, benefit the system.