Charge transport through image charged stabilized states in a single molecule single electron transistor device

The present paper gives an elaborate theoretical description of a new molecular charge transport mechanism applying to a single molecule trapped between two macroscopic electrodes in a solid state device. It is shown by a Hubbard type model of the electronic and electrostatic interactions, that the close proximity of metal electrodes may allow electrons to tunnel from the electrode directly into a very localized image charge stabilized states on the molecule. Due to this mechanism, an exceptionally large number of redox states may be visited within an energy scale which would normally not allow the molecular HOMO-LUMO gap to be transversed. With a reasonable set of parameters, a good fit to recent experimental values may be obtained. The theoretical model is furthermore used to search for the physical boundaries of this effect, and it is found that a rather narrow geometrical space is available for the new mechanism to be effective: In the specific case of oligophenylenevinylene molecules recently explored in such devices several atoms in the terminal benzene rings need to be at van der Waal's distance to the electrode in order for the mechanism to be effective. The model predicts, that chemisorption of the terminal benzene rings too gold electrodes will impede the image charge effect very significantly because the molecule is pushed away from the electrode by the covalent thiol-gold bond.Comment: 9 pages, 5 figue

Association Between APOL1 Genotypes and Risk of Cardiovascular Disease in MESA (Multi-Ethnic Study of Atherosclerosis).

BACKGROUND:APOL1 genetic variants confer an increased risk for kidney disease. Their associations with cardiovascular disease (CVD) are less certain. We aimed to compare the prevalence of subclinical CVD and incidence of atherosclerotic CVD and heart failure by APOL1 genotypes among self-identified black participants of MESA (Multi-Ethnic Study of Atherosclerosis). METHODS AND RESULTS:Cross-sectional associations of APOL1 genotypes (high-risk=2 alleles; low-risk=0 or 1 allele) with coronary artery calcification, carotid-intimal media thickness, and left ventricular mass were evaluated using logistic and linear regression. Longitudinal associations of APOL1 genotypes with incident myocardial infarction, stroke, coronary heart disease, and congestive heart failure were examined using Cox regression. We adjusted for African ancestry, age, and sex. We also evaluated whether hypertension or kidney function markers explained the observed associations. Among 1746 participants with APOL1 genotyping (mean age 62 years, 55% women, mean cystatin C-based estimated glomerular filtration rate 89 mL/min per 1.73 m2, 12% with albuminuria), 12% had the high-risk genotypes. We found no difference in prevalence or severity of coronary artery calcification, carotid-intimal media thickness, or left ventricular mass by APOL1 genotypes. The APOL1 high-risk group was 82% more likely to develop incident heart failure compared with the low-risk group (95% confidence interval, 1.01-3.28). Adjusting for hypertension (hazard ratio, 1.80; 95% confidence interval, 1.00-3.24) but not markers of kidney function (hazard ratio, 1.86; 95% confidence interval, 1.03-3.35) slightly attenuated this association. The APOL1 high-risk genotypes were not significantly associated with other clinical CVD outcomes. CONCLUSIONS:Among blacks without baseline CVD, the APOL1 high-risk variants may be associated with increased risk for incident heart failure but not subclinical CVD or incident clinical atherosclerotic CVD

Femoral Artery Atherosclerosis Is Associated With Physical Function Across the Spectrum of the Ankle-Brachial Index: The San Diego Population Study.

BackgroundThe ankle-brachial index (ABI) is inadequate to detect early-stage atherosclerotic disease, when interventions to prevent functional decline may be the most effective. We determined associations of femoral artery atherosclerosis with physical functioning, across the spectrum of the ABI, and within the normal ABI range.Methods and resultsIn 2007-2011, 1103 multiethnic men and women participated in the San Diego Population Study, and completed all components of the summary performance score. Using Doppler ultrasound, superficial and common femoral intima media thickness and plaques were ascertained. Logistic regression was used to assess associations of femoral atherosclerosis with the summary performance score and its individual components. Models were adjusted for demographics, lifestyle factors, comorbidities, lipids, and kidney function. In adjusted models, among participants with a normal-range ABI (1.00-1.30), the highest tertile of superficial intima media thickness was associated with lower odds of a perfect summary performance score of 12 (odds ratio=0.56 [0.36, 0.87], P=0.009), and lower odds of a 4-m walk score of 4 (0.34 [0.16, 0.73], P=0.006) and chair rise score of 4 (0.56 [0.34, 0.94], P=0.03). Plaque presence (0.53 [0.29, 0.99], P=0.04) and greater total plaque burden (0.61 [0.43, 0.87], P=0.006) were associated with worse 4-m walk performance in the normal-range ABI group. Higher superficial intima media thickness was associated with lower summary performance score in all individuals (P=0.02).ConclusionsFindings suggest that use of femoral artery atherosclerosis measures may be effective in individuals with a normal-range ABI, especially, for example, those with diabetes mellitus or a family history of peripheral artery disease, when detection can lead to earlier intervention to prevent functional declines and improve quality of life

Plasmonic modulator optimized by patterning of active layer and tuning permittivity

We study an ultra-compact plasmonic modulator that can be applied in photonic integrated circuits. The modulator is a metal-insulator-metal waveguide with an additional ultra-thin layer of indium tin oxide (ITO). Bias is applied to the multilayer core by means of metal plates that serve as electrodes. External field changes carrier density in the ultra-thin ITO layer, which influences the permittivity. The metal-insulator-metal system possesses a plasmon resonance, and it is strongly affected by changes in the permittivity of the active layer. To improve performance of the structure we propose several optimizations. We examine influence of the ITO permittivity on the modulator's performance and point out appropriate values. We analyze eigenmodes of the waveguide structure and specify the range for its efficient operation. We show that substituting the continuous active layer by a one-dimension periodic stripes increases transmittance through the device and keeps the modulator's performance at the same level. The dependence on the pattern size and filling factor of the active material is analyzed and optimum parameters are found. Patterned ITO layers allow us to design a Bragg grating inside the waveguide. The grating can be turned on and off, thus modulating reflection from the structure. The considered structure with electrical control possesses a high performance and can efficiently work as a plasmonic component in nanophotonic architectures.Comment: Optics Communications (2012

Exploring novel designs of NLP solvers: Architecture and Implementation of WORHP

Mathematical Optimization in general and Nonlinear Programming in particular, are applied by many scientific disciplines, such as the automotive sector, the aerospace industry, or the space agencies. With some established NLP solvers having been available for decades, and with the mathematical community being rather conservative in this respect, many of their programming standards are severely outdated. It is safe to assume that such usability shortcomings impede the wider use of NLP methods; a representative example is the use of static workspaces by legacy FORTRAN codes. This dissertation gives an account of the construction of the European NLP solver WORHP by using and combining software standards and techniques that have not previously been applied to mathematical software to this extent. Examples include automatic code generation, a consistent reverse communication architecture and the elimination of static workspaces. The result is a novel, industrial-grade NLP solver that overcomes many technical weaknesses of established NLP solvers and other mathematical software

Rhythmic Auditory Stimulation and its Effects on Gait Asymmetries and Function in a Patient with Young-Onset Parkinson’s Disease: A Case Report with 2-month Follow up

Award Winne

Electro-thermal modelling for plasmonic structures in the TLM Method

This paper presents a coupled electromagnetic-thermal model for modelling temperature evolution in nano-size plasmonic heat sources. Both electromagnetic and thermal models are based on the Transmission Line Modelling (TLM) method and are coupled through a nonlinear and dispersive plasma material model. The stability and accuracy of the coupled EM-thermal model is analysed in the context of a nano-tip plasmonic heat source example

Caractérisation de l'activité antibactérienne et de l'implication de certains métabolites de l'oxytétracycline dans le développement de la résistance aux antimicrobiens chez Escherichia coli pathogènes aviaires (APEC)

Le phénomène de la résistance aux antimicrobiens est étroitement associé à l’usage inapproprié des antimicrobiens. Diverses approches alternatives aux antimicrobiens ont été appliquées en production animale, particulièrement dans les filières avicoles, dans le but de préserver l’efficacité de l’arsenal thérapeutique actuel. Cependant, l’activité antibactérienne des produits de dégradation d’antimicrobiens couramment utilisés en aviculture, comme les tétracyclines, reste peu étudiée comme source prometteuse de nouvelles molécules antibactériennes. Ainsi, cette étude avait pour objectifs d’évaluer, in vitro, l’activité antibactérienne de trois produits de dégradation de l’oxytétracycline (OTC) (4-α-épi-OTC (4-EOTC), α-apo-OTC et β-apo-OTC), de déterminer si des souches d’E. coli d’origine aviaire adoptent les mêmes mécanismes de résistance contre l’OTC et ses produits de dégradation, et de caractériser la formation de ces produits dans une simulation du gésier. Pour répondre à ces objectifs, nous avons utilisé la méthode de microdilution, la conjugaison bactérienne et la chromatographie liquide haute performance couplée à la spectrométrie de masse en tandem (HPLC-MS/MS). Nos résultats ont démontré que seule la 4-EOTC était associée à une activité antibactérienne, et la combinaison OTC-4ETOC avait augmentée l’activité antibactérienne de l’OTC. Les expériences de conjugaison ont confirmé que, chez E. coli, les mêmes gènes confèrent une résistance à la fois à l’OTC et à ses produits de dégradation. Dans la simulation du gésier, l’OTC est restée stable, suggérant une biotransformation intestinale ou hépatique, et n’a pas perdu son activité antibactérienne. L’activité antibactérienne confirmée du 4-EOTC constitue un résultat original de notre étude et mérite des investigations complémentaires afin de caractériser de manière exhaustive son spectre d’activité et d’explorer son potentiel pour de futures applications thérapeutiques.Selection and spread of antimicrobial resistant bacteria is closely associated with the inappropriate use of antimicrobials in various sectors. Diverse alternatives to antimicrobials have been used in animal production, particularly in poultry, with the aim of preserving the effectiveness of the current therapeutic arsenal. However, the antibacterial activity of degradation products of commonly used antimicrobials in poultry production, such as tetracyclines, remains poorly investigated as a potential source of therapeutic alternatives. This study therefore aimed to (i) assess in vitro the antibacterial activity of three oxytetracycline (OTC) degradation products—4-α-epi-OTC (4-EOTC), α-apo-OTC, and β-apo-OTC; (ii) determine whether E. coli employs the same resistance mechanisms against OTC and its degradation products; and (iii) characterize the formation of these products in a gizzard simulated conditions. Broth microdilution, bacterial conjugation assay, and high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) were employed to address the objectives of the current study. Our results demonstrated that only 4-EOTC exhibited antibacterial activity, and that the OTC–4-EOTC combination enhanced the antibacterial activity of OTC. Conjugation experiments confirmed that, in E. coli, the same genes confer to resistance to both OTC and its degradation products. In the gizzard simulation, OTC remained stable, suggesting intestinal or hepatic biotransformation, and retained its antibacterial activity. The confirmed antibacterial activity of 4-EOTC represents an original finding of the present study and warrants further investigations to fully characterize its antibacterial activity spectrum and explore its potential for future therapeutic applications