The mapping of the local contributions of Fermi and Coulomb correlation into intracule and extracule density distributions

The contributions of the correlated and uncorrelated components of the electron-pair density to atomic and molecular intracule I(r) and extracule E(R) densities and its Laplacian functions ∇2I(r) and ∇2E(R) are analyzed at the Hartree-Fock (HF) and configuration interaction (CI) levels of theory. The topologies of the uncorrelated components of these functions can be rationalized in terms of the corresponding one-electron densities. In contrast, by analyzing the correlated components of I(r) and E(R), namely, IC(r) and EC(R), the effect of electron Fermi and Coulomb correlation can be assessed at the HF and CI levels of theory. Moreover, the contribution of Coulomb correlation can be isolated by means of difference maps between IC(r) and EC(R) distributions calculated at the two levels of theory. As application examples, the He, Ne, and Ar atomic series, the C2-2, N2, O2+2 molecular series, and the C2H4 molecule have been investigated. For these atoms and molecules, it is found that Fermi correlation accounts for the main characteristics of IC(r) and EC(R), with Coulomb correlation increasing slightly the locality of these functions at the CI level of theory. Furthermore, IC(r), EC(R), and the associated Laplacian functions, reveal the short-ranged nature and high isotropy of Fermi and Coulomb correlation in atoms and molecules

Basis set and electron correlation effects on initial convergence for vibrational nonlinear optical properties of conjugated organic molecules

The level of ab initio theory which is necessary to compute reliable values for the static and dynamic (hyper)polarizabilities of three medium size π-conjugated organic nonlinear optical (NLO) molecules is investigated. With the employment of field-induced coordinates in combination with a finite field procedure, the calculations were made possible. It is stated that to obtain reasonable values for the various individual contributions to the (hyper)polarizability, it is necessary to include electron correlation. Based on the results, the convergence of the usual perturbation treatment for vibrational anharmonicity was examined

Multisensor change detection with nonlinear canonical correlation

The analysis of multi-modal and multi-sensor images is nowadays of paramount importance for Earth Observation (EO) applications. There exist a variety of methods that aim at fusing the different sources of information to obtain a compact representation of such datasets. However, for change detection existing methods are often unable to deal with heterogeneous image sources and very few consider possible nonlinearities in the data. Additionally, the availability of labeled information is very limited in change detection applications. For these reasons, we present the use of a semi-supervised kernel-based feature extraction technique. It incorporates a manifold regularization accounting for the geometric distribution and jointly addressing the small sample problem. An exhaustive example using Landsat 5 data illustrates the potential of the method for multi-sensor change detection.

Iterative image reconstruction techniques: cardiothoracic computed tomography applications.

Iterative image reconstruction algorithms provide significant improvements over traditional filtered back projection in computed tomography (CT). Clinically available through recent advances in modern CT technology, iterative reconstruction enhances image quality through cyclical image calculation, suppressing image noise and artifacts, particularly blooming artifacts. The advantages of iterative reconstruction are apparent in traditionally challenging cases-for example, in obese patients, those with significant artery calcification, or those with coronary artery stents. In addition, as clinical use of CT has grown, so have concerns over ionizing radiation associated with CT examinations. Through noise reduction, iterative reconstruction has been shown to permit radiation dose reduction while preserving diagnostic image quality. This approach is becoming increasingly attractive as the routine use of CT for pediatric and repeated follow-up evaluation grows ever more common. Cardiovascular CT in particular, with its focus on detailed structural and functional analyses, stands to benefit greatly from the promising iterative solutions that are readily available.

Techniques d'évaluation de la force des muscles respiratoires. [Techniques for assessing respiratory muscle strength.]

La faiblesse des muscles respiratoires peut entraîner une dyspnée, un encombrement bronchique et une insuffisance respiratoire potentiellement fatale. L'évaluation de la force musculaire respiratoire s'impose donc dans les affections neuro-musculaires, mais également dans les situations de dyspnée inexpliquée par une première évaluation cardiaque et pulmonaire. À la spirométrie, une faiblesse musculaire est suspectée sur la base de la boucle débit-volume montrant un débit de pointe émoussé et une fin prématurée de l'expiration. Une diminution importante de la capacité vitale en position couchée suggère une paralysie diaphragmatique. La force inspiratoire est mesurée par la pression inspiratoire maximale (PImax) contre une quasi-occlusion des voies aériennes. Ce test relativement difficile est d'interprétation délicate en cas de collaboration insuffisante. La mesure de la pression nasale sniff (SNIP) est une alternative utile, car elle élimine le problème des fuites autour de l'embout buccal et la réalisation du reniflement est facile. De même, la pression trans-diaphragmatique sniff mesure la force du diaphragme au moyen de sondes oesophagienne et gastrique. En cas de collaboration insuffisante, on peut recourir à la stimulation magnétique des nerfs phréniques qui induit une contraction non-volontaire du diaphragme. La force expiratoire est mesurée par la pression expiratoire maximale (PEmax) contre une quasi-occlusion. La force disponible pour tousser est mesurée par la pression gastrique à la toux, ou plus simplement par le débit de pointe à la toux. Chez les patients à risque, la mesure de la force des muscles respiratoires permet d'instaurer à temps une assistance ventilatoire ou à la toux.

Combination of fluorescence microscopy and nanomotion detection to characterize bacteria.

Antibiotic-resistant pathogens are a major health concern in everyday clinical practice. Because their detection by conventional microbial techniques requires minimally 24 h, some of us have recently introduced a nanomechanical sensor, which can reveal motion at the nanoscale. By monitoring the fluctuations of the sensor, this technique can evidence the presence of bacteria and their susceptibility to antibiotics in less than 1 h. Their amplitude correlates to the metabolism of the bacteria and is a powerful tool to characterize these microorganisms at low densities. This technique is new and calls for an effort to optimize its protocol and determine its limits. Indeed, many questions remain unanswered, such as the detection limits or the correlation between the bacterial distribution on the sensor and the detection's output. In this work, we couple fluorescence microscopy to the nanomotion investigation to determine the optimal experimental protocols and to highlight the effect of the different bacterial distributions on the sensor.

Analysis and evaluation of techniques for the extraction of classes in the ontology learning process

This paper analyzes and evaluates, in the context of Ontology learning, some techniques to identify and extract candidate terms to classes of a taxonomy. Besides, this work points out some inconsistencies that may be occurring in the preprocessing of text corpus, and proposes techniques to obtain good terms candidate to classes of a taxonomy.

Monitoring multiple angiogenesis-related molecules in the blood of cancer patients shows a correlation between VEGF-A and MMP-9 levels before treatment and divergent changes after surgical vs. conservative therapy.

Anti-angiogenic therapies are currently in cancer clinical trials, but to date there are no established tests for evaluating the angiogenic status of a patient. We measured 11 circulating angiogenesis-associated molecules in cancer patients before and after local treatment. The purpose of our study was to screen for possible relationships among the different molecules and between individual molecules and tumor burden. We measured VEGF-A, PlGF, SCF, MMP-9, EDB+ -fibronectin, sVEGFR-2, sVEGFR-1, salphaVbeta3, sTie-2, IL-8 and CRP in the blood of 22 healthy volunteers, 17 early breast, 17 early colorectal, and 8 advanced sarcoma/melanoma cancer patients. Breast cancer patients had elevated levels of VEGF-A and sTie-2, colorectal cancer patients of VEGF-A, MMP-9, sTie-2, IL-8 and CRP, and melanoma/sarcoma patients of sVEGFR-1. salphaVbeta3 was decreased in colorectal cancer patients. A correlation between VEGF-A and MMP-9 was found. After tumor removal, MMP-9 and salphaVbeta3 significantly decreased in breast and CRP in colorectal cancer, whereas sVEGFR-1 increased in colorectal cancer patients. In sarcoma/melanoma patients treated regionally with TNF and chemotherapy we observed a rise in VEGF-A, SCF, VEGFR-2, MMP-9, Tie-2 and CRP, a correlation between CRP and IL-8, and a decreased in sVEGFR-1 levels. In conclusion, among all factors measured, only VEGF-A and MMP-9 consistently correlated to each other, elevated CRP levels were associated with tumor burden, whereas sVEGF-R1 increased after tumor removal in colorectal cancer. Treatment with chemotherapy and TNF induced changes consistent with an angiogenic switch. These results warrant a prospective study to compare the effect of surgical tumor removal vs. chemotherapy on some of these markers and to evaluate their prognostic/predictive value.

Impact of antenna correlation on the capacity of multiantenna channels

This paper applies random matrix theory to obtain analytical characterizations of the capacity of correlated multiantenna channels. The analysis is not restricted to the popular separable correlation model, but rather it embraces a more general representation that subsumesmost of the channel models that have been treated in the literature. For arbitrary signal-to-noise ratios (SNR), the characterization is conducted in the regime of large numbers of antennas. For the low- and high-SNR regions, in turn, we uncover compact capacity expansions that are valid for arbitrary numbers of antennas and that shed insight on how antenna correlation impacts the tradeoffs between power, bandwidth and rate.

Correlation of diffusion tensor tractography and intraoperative macrostimulation during deep brain stimulation for Parkinson disease.

Object The purpose of this study was to investigate whether diffusion tensor imaging (DTI) of the corticospinal tract (CST) is a reliable surrogate for intraoperative macrostimulation through the deep brain stimulation (DBS) leads. The authors hypothesized that the distance on MRI from the DBS lead to the CST as determined by DTI would correlate with intraoperative motor thresholds from macrostimulations through the same DBS lead. Methods The authors retrospectively reviewed pre- and postoperative MRI studies and intraoperative macrostimulation recordings in 17 patients with Parkinson disease (PD) treated by DBS stimulation. Preoperative DTI tractography of the CST was coregistered with postoperative MRI studies showing the position of the DBS leads. The shortest distance and the angle from each contact of each DBS lead to the CST was automatically calculated using software-based analysis. The distance measurements calculated for each contact were evaluated with respect to the intraoperative voltage thresholds that elicited a motor response at each contact. Results There was a nonsignificant trend for voltage thresholds to increase when the distances between the DBS leads and the CST increased. There was a significant correlation between the angle and the voltage, but the correlation was weak (coefficient of correlation [R] = 0.36). Conclusions Caution needs to be exercised when using DTI tractography information to guide DBS lead placement in patients with PD. Further studies are needed to compare DTI tractography measurements with other approaches such as microelectrode recordings and conventional intraoperative MRI-guided placement of DBS leads.

Investigation into Improved Pavement Curing Materials and Techniques: Part 2 - Phase III, March 2003

Appropriate curing is important for concrete to obtain the designed properties. This research was conducted to evaluate the curing effects of different curing materials and methods on pavement properties. At present the sprayed curing compound is a common used method for pavement and other concrete structure construction. Three curing compounds were selected for testing. Two different application rates were employed for the white-pigmented liquid curing compounds. The concrete properties of temperature, moisture content, conductivity, and permeability were examined at several test locations. It was found, in this project, that the concrete properties varied with the depth. Of the tests conducted (maturity, sorptivity, permeability, and conductivity), conductivity appears to be the best method to evaluate the curing effects in the field and bears potential for field application. The results indicated that currently approved curing materials in Iowa, when spread uniformly in a single or double application, provide adequate curing protection and meet the goals of the Iowa Department of Transportation. Experimental curing methods can be compared to this method through the use of conductivity testing to determine their application in the field.

Investgiation into Improved Pavement Curing Materials and Techniques: Part 1 - Phases I and II, April 2002

Concrete curing is closely related to cement hydration, microstructure development, and concrete performance. Application of a liquid membrane-forming curing compound is among the most widely used curing methods for concrete pavements and bridge decks. Curing compounds are economical, easy to apply, and maintenance free. However, limited research has been done to investigate the effectiveness of different curing compounds and their application technologies. No reliable standard testing method is available to evaluate the effectiveness of curing, especially of the field concrete curing. The present research investigates the effects of curing compound materials and application technologies on concrete properties, especially on the properties of surface concrete. This report presents a literature review of curing technology, with an emphasis on curing compounds, and the experimental results from the first part of this research—lab investigation. In the lab investigation, three curing compounds were selected and applied to mortar specimens at three different times after casting. Two application methods, single- and double-layer applications, were employed. Moisture content, conductivity, sorptivity, and degree of hydration were measured at different depths of the specimens. Flexural and compressive strength of the specimens were also tested. Statistical analysis was conducted to examine the relationships between these material properties. The research results indicate that application of a curing compound significantly increased moisture content and degree of cement hydration and reduced sorptivity of the near-surface-area concrete. For given concrete materials and mix proportions, optimal application time of curing compounds depended primarily upon the weather condition. If a sufficient amount of a high-efficiency-index curing compound was uniformly applied, no double-layer application was necessary. Among all test methods applied, the sorptivity test is the most sensitive one to provide good indication for the subtle changes in microstructure of the near-surface-area concrete caused by different curing materials and application methods. Sorptivity measurement has a close relation with moisture content and degree of hydration. The research results have established a baseline for and provided insight into the further development of testing procedures for evaluation of curing compounds in field. Recommendations are provided for further field study.

Parallel Research, Multiple Intellectual Property Right Protection Instruments, and the Correlation among R&D Projects, September 2005

The choice of a research path in attacking scientific and technological problems is a significant component of firms’ R&D strategy. One of the findings of the patent races literature is that, in a competitive market setting, firms’ noncooperative choices of research projects display an excessive degree of correlation, as compared to the socially optimal level. The paper revisits this question in a context in which firms have access to trade secrets, in addition to patents, to assert intellectual property rights (IPR) over their discoveries. We find that the availability of multiple IPR protection instruments can move the paths chosen by firms engaged in an R&D race toward the social optimum.