Shot Noise with Interaction Effects in Single Walled Carbon Nanotubes

We have measured shot noise in single walled carbon nanotubes (SWNT) with good contacts at 4.2 K at low frequencies ($f=600 - 850$ MHz). We find a strong modulation of shot noise over the Fabry-Perot pattern; in terms of differential Fano factor the variation ranges over 0.4 - 1.2. The shot noise variation, in combination with differential conductance, is analyzed using two (spin-degenerate) modes with different, energy-dependent transmission coefficients. No power law dependence of shot noise, as expected for Luttinger liquids, was found in our measurements.Comment: 5 pages, 4 figure

Usefulness of a quantitative real-time PCR assay using serum samples to discriminate between inactive, serologically positive and active human brucellosis

AbstractDiagnosis of brucellosis can be difficult in certain scenarios where conventional microbiological techniques have important limitations. The aim of this study was to develop a LightCycler Quantitative PCR assay in serum samples to discriminate between active and past brucellosis. In total, 110 serum samples from 46 brucellosis patients and 64 controls, including persons who had recently been treated for brucellosis, asymptomatic persons exposed to brucellosis, and patients with febrile syndromes involving a differential diagnosis with brucellosis, were studied. Brucella spp.-specific sequences of the PCR primers and probe were selected from the gene encoding an immunogenic membrane protein of 31 kDa (BCSP31). The analytical sensitivity was 1 × 101 fg of Brucella DNA. The mean threshold cycles for brucellosis patients and controls were 31.8 ± 1.7 and 35.4 ± 1.1, respectively (p <0.001). The best cut-off for bacterial DNA load was 5 × 103 copies/mL. At this cut-off, the area under the receiver operating characteristic curves was 0.963 (95% CI 0.920–1.005), with a sensitivity of 93.5% and a specificity of 98.4%. Under the assay conditions, the LightCycler Quantitative PCR in serum samples seems to be highly reproducible, rapid, sensitive and specific. It is therefore a useful method for both the initial diagnosis and the differentiation between past and active brucellosis

Controlling supercurrents using single-walled carbon nanotube weak links

We have investigated proximity-induced supercurrents in single-walled carbon nanotubes. Phase diffusion is found to be present in the maximum measured supercurrent of 4.8 nA, which results in a minimum of 100Ω zero bias resistance in superconducting state. We also observe that the supercurrent is very sensitive to the measurement bandwidth and large phase fluctuations can even destroy the supercurrents. Our results shed light on the methods of how to improve the performance of high frequency superconducting single-walled nanotube devices.Peer reviewe

Measurements of shot noise in single walled carbon nanotubes

We have measured shot noise in single walled carbon nanotubes (SWNT) at 4.2K over frequencies f = 600 – 850 MHz. Here we report results obtained on shot noise without DC bias by applying an AC modulation at ω0 and recording the noise variation at 2ω0: the Fano factor is obtained by extrapolating down to zero excitation amplitude. We also discuss the applicability of this method in samples which have strongly non‐linear IV characteristics like carbon nanotubes. The obtained results are compared with regular differential noise measurements where both DC and AC bias are employed.Peer reviewe

Single-walled carbon nanotube weak links in Kondo regime with zero-field splitting

We have investigated proximity-induced supercurrents in single-walled carbon nanotubes in the Kondo regime and compared them with supercurrents obtained on the same tube with Fabry-Pérot resonances. Our data display a wide distribution of Kondo temperatures TK=1–14 K, and the measured critical current ICM vs TK displays two distinct branches; these branches, distinguished by zero-field splitting of the normal-state Kondo conductance peak, differ by an order of magnitude at large values of TK. Evidence for renormalization of Andreev levels in Kondo regime is also found.Peer reviewe

Rapid diagnosis of human brucellosis by SYBR Green I-based real-time PCR assay and melting curve analysis in serum samples

SUMMARYThe aim of this study was to develop a LightCycler-based real-time PCR (LC-PCR) assay and to evaluate its diagnostic use for the detection of Brucella DNA in serum samples. Following amplification of a 223-bp gene sequence encoding an immunogenetic membrane protein (BCSP31) specific for the Brucella genus, melting curve and DNA sequencing analysis was performed to verify the specificity of the PCR products. The intra- and inter-assay variation coefficients were 1.3% and 6.4%, respectively, and the detection limit was 5 fg of Brucella DNA (one genome equivalent). After optimisation of the PCR assay conditions, a standard curve was obtained with a linear range (correlation coefficient = 0.99) over seven orders of magnitude from 107 to 10 fg of Brucella DNA. The LC-PCR assay was found to be 91.9% sensitive and 95.4% specific when tested with 65 negative control samples and 62 serum samples from 60 consecutive patients with active brucellosis. The assay is reproducible, easily standardised, minimises the risk of infection in laboratory workers, and has a total processing time of < 2 h. It could therefore form a promising and practical approach for the rapid diagnosis of human brucellosis

Prevalencia de candidiasis vaginal en una población obstétrica de bajo riesgo en Santander

ObjetivoConocer la prevalencia de candidiasis vaginal en embarazadas controladas desde atención primaria y ver si está aumentando con el paso del tiempo.DiseñoEstudio descriptivo, retrospectivo del universo de mujeres embarazadas.EmplazamientoZona Básica de Salud Cazoña (34.783 habitantes).SujetosToda la población obstétrica controlada en nuestro centro de salud desde 1992 a 1997, ambos inclusive.Mediciones y resultadosEstudio retrospectivo de las historias clínicas de todas las mujeres embarazadas captadas en nuestro centro de salud (878 embarazos). Descartados los derivados a tocólogo, abortos y partos prematuros, se han valorado 549 embarazos (62,30% del total) normales, de bajo riesgo, controlados hasta el final por atención primaria, con un rango de edad de 16-40 años. La prevalencia media de candidiasis es de un 18% (IC, 15,0-21,6). Su frecuencia aumenta a medida que se incrementa el número de gestaciones y disminuye a medida que aumenta la edad de la embarazada.ConclusionesLa prevalencia encontrada en nuestro estudio es de un 18%, y no está aumentando a medida que pasan los años.ObjectivesTo find the prevalence of vaginal candidiasis in pregnant women monitored through primary care and to see whether it is on the increase.DesignDescriptive and retrospective study of pregnant women.SettingCazoña Health District (34783 inhabitants).SubjectsThe entire obstetric population monitored by our health centre between 1992 and 1997 inclusive.Measurements and resultsRetrospective study of clinical histories of all the pregnant women seen at our health centre (878 pregnancies). After discounting those referred to obstetricians, abortions/ miscarriages and premature births, 549 normal low-risk pregnancies (62.30% of the total) were monitored to completion in primary care. The women's age range was 16 to 40. The mean prevalence of candidiasis was 18% (CI, 15.0-21.6). Its frequency increased as the number of pregnancies increased and dropped as the age of the pregnant women increased.ConclusionsPrevalence found in our study was 18% and did not increase as the years passed

Spatial and temporal distribution of Mycobacterium tuberculosis complex infection in Eurasian badger (Meles meles) and cattle in Asturias, Spain

Trabajo presentado al: 69th Wildlife Disease Association and 14th European Wildlife Disease Association Conference. Cuenca, Spain. p. 66. 31 agosto-2 septiembre

Selenium and impaired physical function in US and Spanish older adults

Background: Selenium (Se) is a trace element with a narrow safety margin. Objectives: To evaluate the cross-sectional and longitudinal dose-response association between Se exposure and measures of impaired physical function and disability in older adults. Design: NHANES 2011–2014 cross-sectional (US, n = 1733, age ≥60 years) and Seniors-ENRICA-2 2017–2019 cross-sectional and longitudinal (Spain, n = 2548 and 1741, respectively, age ≥65 years) data were analyzed. Whole blood and serum Se levels were measured using inductively coupled plasma-mass spectrometry. Lowerextremity performance was assessed with the Short Physical Performance Battery, and muscle weakness with a dynamometer. Incident mobility and agility limitations, and disability in instrumental activities of daily living (IADL) were ascertained with standardized questionnaires. Analyses were adjusted for relevant confounders, including physical activity. Results across studies were pooled using random-effects meta-analysis. Results: Meta-analyzed odds ratios (95% confidence interval) per log2 increase in whole blood Se were 0.54 (0.32; 0.76) for weakness, 0.59 (0.34; 0.83) for impaired lower-extremity performance, 0.48 (0.31; 0.68) for mobility limitations, 0.71 (0.45; 0.97) for agility limitations, and 0.34 (0.12; 0.56) for disability in at least one IADL. Analyses for serum Se in NHANES showed similar results. Findings suggest the inverse association with grip strength is progressive below 140 μg/L (p-value for non-linear trend in the Seniors-ENRICA-2 study = 0.13), and above 140 μg/L (p-value for non-linear trend in NHANES = 0.11). In the Seniors-ENRICA-2 cohort, with a 2.2 year follow-up period, a doubling in baseline Se levels were associated with a lower incidence of weakness [odds ratio (95% confidence interval): 0.45 (0.22; 0.91)], impaired lower-extremity performance [0.63 (0.32; 1.23)], mobility [0.43 (0.21; 0.91)] and agility [0.38 (0.18; 0.78)] limitations. Discussion: In US and Spanish older adults, Se concentrations were inversely associated with physical function limitations. Further studies are needed to elucidate underlying mechanisms.Instituto de Salud Carlos III European Commission PI18/287 16/609State Secretary of R + D + I PID2019-108973RB-C21/C22European Social Fund (ESF) European Commissio