Quantum interference through gated single-molecule junctions

We discuss the general form of the transmission spectrum through a molec- ular junction in terms of the Green function of the isolated molecule. By introducing a tight binding method, we are able to translate the Green func- tion properties into practical graphical rules for assessing beforehand the possible existence of antiresonances in an energy range for a given choice of connecting sites. The analysis is exemplified with a benzene molecule under a hypothetical local gate, which allows one to continuously tune the on-site energy of single atoms, for various connection topologies and gate positions.Comment: 17 pages, 5 figure

Quantum transport through single and multilayer icosahedral fullerenes

We use a tight-binding Hamiltonian and Green functions methods to calculate the quantum transmission through single-wall fullerenes and bilayered and trilayered onions of icosahedral symmetry attached to metallic leads. The electronic structure of the onion-like fullerenes takes into account the curvature and finite size of the fullerenes layers as well as the strength of the intershell interactions depending on to the number of interacting atom pairs belonging to adjacent shells. Misalignment of the symmetry axes of the concentric icosahedral shells produces breaking of the level degeneracies of the individual shells, giving rise some narrow quasi-continuum bands instead of the localized discrete peaks of the individual fullerenes. As a result, the transmission function for non symmetrical onions are rapidly varying functions of the Fermi energy. Furthermore, we found that most of the features of the transmission through the onions are due to the electronic structure of the outer shell with additional Fano-like antiresonances arising from coupling with or between the inner shells.Comment: 16 pages, 5 figur

Impurity Effects in Two-Electron Coupled Quantum Dots: Entanglement Modulation

We present a detailed analysis of the electronic and optical properties of two-electron quantum dots with a two-dimensional Gaussian confinement potential. We study the effects of Coulomb impurities and the possibility of manipulate the entanglement of the electrons by controlling the confinement potential parameters. The degree of entanglement becomes highly modulated by both the location and charge screening of the impurity atom, resulting two regimes: one of low entanglement and other of high entanglement, with both of them mainly determined by the magnitude of the charge. It is shown that the magnitude of the oscillator strength of the system could provide an indication of the presence and characteristics of impurities that could largely influence the degree of entanglement of the system.Comment: Regular Article (Journal of Physics B, in press), 9 pages, 10 figure

Transmission through a quantum dot molecule embedded in an Aharonov-Bohm interferometer

We study theoretically the transmission through a quantum dot molecule embedded in the arms of an Aharonov-Bohm four quantum dot ring threaded by a magnetic flux. The tunable molecular coupling provides a transmission pathway between the interferometer arms in addition to those along the arms. From a decomposition of the transmission in terms of contributions from paths, we show that antiresonances in the transmission arise from the interference of the self-energy along different paths and that application of a magnetic flux can produce the suppression of such antiresonances. The occurrence of a period of twice the quantum of flux arises to the opening of transmission pathway through the dot molecule. Two different connections of the device to the leads are considered and their spectra of conductance are compared as a function of the tunable parameters of the model.Comment: 8 pages, 5 figure

Laser-induced splittings in the nuclear magnetic resonance spectra of the rare gases

Circularly polarized laser field causes a shift in the nuclear magnetic resonance (NMR) spectra of all substances. The shift is proportional to the intensity of the laser beam and yields oppositely signed values for left- and right-circularly polarized light, CPL -/+, respectively. Rapid switching -- in the NMR time scale -- between CPL+ and CPL- gives rise to a splitting of the NMR resonance lines. We present uncorrelated and correlated quadratic response calculations of the splitting per unit of beam intensity in the NMR spectra of $^{21}$Ne, $^{83}$Kr, and $^{129}$Xe. We study both the regions far away from and near to optical resonance and predict off-resonance shifts of the order 0.01, 0.1, and $1\times 10^{-6}$ Hz for $^{21}$Ne, $^{83}$Kr, and $^{129}$Xe, respectively, for a beam intensity of 10 W/cm$^2$. Enhancement by several orders of magnitude is predicted as the beam frequency approaches resonance. Only then can the effect on guest $^{129}$Xe atoms be potentially useful as a probe of the properties of the host material.Comment: 5 pages, 1 figur

Antioxidant, antibacterial, and anti-SARS-CoV Activity of Commercial Products of \u3cem\u3eXylopia\u3c/em\u3e (\u3cem\u3eXylopia aethiopica\u3c/em\u3e)

Xylopia aethiopica (Annonaceae) is a spice and medicinal plant that grows wild in many West African countries (from Liberia to Nigeria) and is locally known as Guinea pepper, grains of Selim, hwentia and uda. The dried fruits are used as a flavoring for soups and traditionally in decoctions as an analgesic and anti-inflammatory, as well as a treatment for infections. The medicinal properties of the fruits are associated with the presence of phenolics and essential oil constituents. We studied the total phenols, total flavonoids, and antioxidant activity in different X. aethiopica extracts using spectrophotometry. We found variation in total phenolic and flavonoids and antioxidant capacity between different samples and different extraction solvents. Antibacterial activity against Escherichia coli and Bacillus subtilis were evaluated using a spectrophotometric assay and Kirby-Bauer test. Additionally, a pseudoviral cell-based assay was used to test the antiviral activity against severe acute respiratory syndrome coronaviruses (SARS-CoV-1 and SARS-CoV-2). High total phenolic and flavonoid content was correlated with high antioxidant capacity. Results of antibacterial tests indicated that one Xylopia extract potentially has strong antibacterial activity against gram-positive bacteria B. subtilis. The pseudoviral assay showed moderate antiviral activity against SARS-CoV-1 and SARS-CoV-2

Treatment outcomes 24 months after initiating short, all-oral bedaquiline-containing or injectable-containing rifampicin-resistant tuberculosis treatment regimens in South Africa : a retrospective cohort study

DATA SHARING : The data used for this analysis in the form of deidentified participant data and a data dictionary will be made available after publication. Investigators wishing to access these data will need to have an approved research proposal and complete a data access agreement. All inquiries should be sent to the corresponding author ([email protected] or [email protected]).SUPPLEMENTARY MATERIAL 1 : French translation of the abstract. SUPPLEMENTARY MATERIAL 2 : Appendices.BACKGROUND : There is a need for short and safe all-oral treatment of rifampicin-resistant tuberculosis. We compared outcomes up to 24 months after treatment initiation for patients with rifampicin-resistant tuberculosis in South Africa treated with a short, all-oral bedaquiline-containing regimen (bedaquiline group), or a short, injectable-containing regimen (injectable group). METHODS : Patients with rifampicin-resistant tuberculosis, aged 18 years or older, eligible for a short regimen starting treatment between Jan 1 and Dec 31, 2017, with a bedaquiline-containing or WHO recommended injectable-containing treatment regimen of 9–12 months, registered in the drug-resistant tuberculosis database (EDRWeb), and with known age, sex, HIV status, and national identification number were eligible for study inclusion; patients receiving linezolid, carbapenems, terizidone or cycloserine, delamanid, or para-aminosalicylic acid were excluded. Bedaquiline was given at a dose of 400 mg once daily for two weeks followed by 200 mg three times a week for 22 weeks. To compare regimens, patients were exactly matched on HIV and ART status, previous tuberculosis treatment history, and baseline acid-fast bacilli smear and culture result, while propensity score matched on age, sex, province of treatment, and isoniazid-susceptibility status. We did binomial linear regression to estimate adjusted risk differences (aRD) and 95% CIs for 24-month outcomes, which included: treatment success (ie, cure or treatment completion without evidence of recurrence) versus all other outcomes, survival versus death, disease free survival versus survival with treatment failure or recurrence, and loss to follow-up versus all other outcomes. FINDINGS : Overall, 1387 (14%) of 10152 patients with rifampicin-resistant tuberculosis treated during 2017 met inclusion criteria; 688 in the bedaquiline group and 699 in the injectable group. Four patients (1%) had treatment failure or recurrence, 44 (6%) were lost to follow-up, and 162 (24%) died in the bedaquiline group, compared with 17 (2%), 87 (12%), and 199 (28%), respectively, in the injectable group. In adjusted analyses, treatment success was 14% (95% CI 8–20) higher in the bedaquiline group than in the injectable group (70% vs 57%); loss to follow-up was 4% (1–8) lower in the bedaquiline group (6% vs 12%); and disease-free survival was 2% (0–5) higher in the bedaquiline group (99% vs 97%). The bedaquiline group had 8% (4–11) lower risk of mortality during treatment (17·0% vs 22·4%), but there was no difference in mortality post-treatment. INTERPRETATION : Patients in the bedaquiline group experienced significantly higher rates of treatment success at 24 months. This finding supports the use of short bedaquiline-containing regimens in eligible patients.WHO Global TB Programme.http://www.thelancet.com/infectionhj2023Medical Microbiolog

Generations UNAB No.4

Esta cuarta edición de la revista Generaciones UNAB, gira en torno a la celebración de los 40 años de inicio de labores de la Facultad de Derecho, cuyo primeros 25 graduados obtuvieron su título en 1978; así como a la celebración de los primeros 30 años de inicio de labores de la Facultad de Comunicación Social que graduó a sus primeros 17 estudiantes en 1987. Hoy, cuatro y tres décadas después del inicio de labores respectivamente, y atendiendo al compromiso institucional con la región, ña Universidad ha permitido que Santander, Colombia y el mundo cuenten con 3.104 abogados y 1.647 comunicadores sociales que se destacan por su compromiso con la sociedad, su trabajo en equipo, ética y valores en el ejercicio profesional.Editorial; Por Marcela Peralta Bautista…03 Columnista invitado, Facultades bien dirigidas; Por Alfonso Gómez Gómez…06 40 años de la Facultad de Derecho…08 Cuatro décadas formando futuro; Por José Manuel Arias Carrizosa…09 Una facultad de libertadores; Por Jaime Gutiérrez Rivero…10 Defendiendo la libertad del conocimiento; Por Sergio Rangel Consuegra…11 La cara humana del derecho; Por Jorge González Aranda…13 La decanatura marcó mi vida; Por Gabriel Burgos Mantilla…14 La unión hace la fuerza; Por Jorge Castillo Rugeles…16 Mis estudiantes son lo más importante; Por Rodolfo Mantilla Jácome…18 La hermenéutica jurídica como sello diferenciador; Por Juan Carlos Acuña Gutiérrez...20 Equipo de trabajo y apoyo directivo; Por Jorge Eduardo Lamo Gómez…22 30 años de la Facultad de Comunicación Social…25 Haciendo el sueño realidad; Por Carlos H. Gómez…26 Un compromiso de vida; Por Maria Isabel León Carreño…28 Construir debatiendo; Por Rodrigo Velasco Ortiz…30 La importancia de potenciar capacidades; Por Luz Amalia Camacho Velásquez...32 Una propuesta académica única; Por Iván Darío Montoya Osorio…34 Graduados Destacando…37 Docente en la Facultad de Derecho UNAB…38 Comunicación Social-Periodista de la UNAB; Por Sonia Díaz…39 Emprendedores UNAB “Apps.com”; Por Marcela Peralta Bautista…40 Instigación “Trata de personas”; Por Lya Fernández de Mantilla, Johana Marcela Reyes…42 Encuentros…45This fourth edition of the magazine Generaciones UNAB, revolves around the celebration of 40 years of beginning of work of the Faculty of Law, whose first 25 graduates obtained their degree in 1978; as well as the celebration of the first 30 years of beginning of work of the Faculty of Social Communication that graduated its first 17 students in 1987. Today, four and three decades after the start of work respectively, and in response to the institutional commitment to the region, ña University has allowed Santander, Colombia and the world to have 3,104 lawyers and 1,647 social communicators who stand out for their commitment to society , their teamwork, ethics and values ​​in professional practice