Noise at a Fermi-edge singularity

We present noise measurements of self-assembled InAs quantum dots at high magnetic fields. In comparison to I-V characteristics at zero magnetic field we notice a strong current overshoot which is due to a Fermi-edge singularity. We observe an enhanced suppression in the shot noise power simultaneous to the current overshoot which is attributed to the electron-electron interaction in the Fermi-edge singularity

Wage Dispersion and Decentralization of Wage Bargaining

This paper studies how decentralization of wage bargaining from sector to firm-level influences wage levels and wage dispersion. We use detailed panel data covering a period of decentralization in the Danish labor market. The decentralization process provides variation in the individual worker's wage-setting system that facilitates identification of the effects of decentralization. We find a wage premium associated with firm-level bargaining relative to sector-level bargaining, and that the return to skills is higher under the more decentralized wage-setting systems. Using quantile regression, we also find that wages are more dispersed under firm-level bargaining compared to more centralized wage-setting systems.wage bargaining, decentralization, wage dispersion

Wage Dispersion and Decentralization of Wage Bargaining

This paper studies how decentralization of wage bargaining from sector to firm level influences wage levels and wage dispersion. We use a detailed panel data set covering a period of decentralization in the Danish labor market. The decentralization process provides exogenous variation in the individual worker's wage-setting system that facilitates identification of the effects of decentralization. Consistent with predictions we find that wages are more dispersed under firm-level bargaining compared to more centralized wage-setting systems. However, the differences across wage-setting systems are reduced substantially when controlling for unobserved individual level heterogeneity.Wage bargaining; decentralization; panel data quantile regression

Enhanced Shot Noise in Tunneling through a Stack of Coupled Quantum Dots

We have investigated the noise properties of the tunneling current through vertically coupled self-assembled InAs quantum dots. We observe super-Poissonian shot noise at low temperatures. For increased temperature this effect is suppressed. The super-Poissonian noise is explained by capacitive coupling between different stacks of quantum dots

Posturographic pattern of patients with chronic subjective dizziness before and after vestibular rehabilitation.

Chronic subjective dizziness (CSD) is frequently encountered in neurotology clinics. This diagnosis is mainly clinical, but computerized dynamic posturography (CDP) could be a helpful instrumental tool in the identification of these patients and validation of the treatment. This study was aimed to look for a specific posturographic pattern among patients diagnosed with CSD, and to eventually visualize improvement after vestibular rehabilitation. Single center, retrospective review from 2009 to 2014. We included patients diagnosed with CSD who underwent CDP in their neurotologic assessment. For those patients who benefited from vestibular rehabilitation, we compared their pre- and post-rehabilitation posturographies. We included 114 patients, of whom 74% had known anxiety disorders and 33% a history of past vestibular disorder. 62% of the assessment posturographies were abnormal. The most affected sub-items were limit of stability, composite score of sensory organization tests and condition 5 in respectively 34%, 23% and 20% of the cases. In univariate analysis, only pathologic videonystagmography and history of unilateral vestibular dysfunction were significantly related to abnormal posturography. In the 42 patients who had vestibular rehabilitation and a post rehabilitation posturography, the proportion of abnormal posturography significantly dropped from 79% to 33% (p < 0.001). When it was assessed, 79% of the patients reported a subjective improvement. Patients with CSD have a high rate of abnormal posturography, but without a specific pattern. Vestibular rehabilitation is an effective tool in the therapeutic armamentarium

Bioengineered Nisin A Derivatives with Enhanced Activity against Both Gram Positive and Gram Negative Pathogens

peer-reviewedNisin is a bacteriocin widely utilized in more than 50 countries as a safe and natural antibacterial food preservative. It is the most extensively studied bacteriocin, having undergone decades of bioengineering with a view to improving function and physicochemical properties. The discovery of novel nisin variants with enhanced activity against clinical and foodborne pathogens has recently been described. We screened a randomized bank of nisin A producers and identified a variant with a serine to glycine change at position 29 (S29G), with enhanced efficacy against S. aureus SA113. Using a site-saturation mutagenesis approach we generated three more derivatives (S29A, S29D and S29E) with enhanced activity against a range of Gram positive drug resistant clinical, veterinary and food pathogens. In addition, a number of the nisin S29 derivatives displayed superior antimicrobial activity to nisin A when assessed against a range of Gram negative food-associated pathogens, including E. coli, Salmonella enterica serovar Typhimurium and Cronobacter sakazakii. This is the first report of derivatives of nisin, or indeed any lantibiotic, with enhanced antimicrobial activity against both Gram positive and Gram negative bacteria.This work was supported by the Irish Government under the National Development Plan, through Science Foundation Ireland Investigator awards (10/IN.1/B3027) and (06/IN.1/B98) (http://www.sfi.ie)

Long-term denudation rates from the Central Andes (Chile) estimated from a digital elevation model using the black top hat function and inverse distance weighting : implications for the neogene climate of the Atacama Desert

A methodology for determining long-term denudation rates from morphologic markers in a Digital Elevation Model (DEM) is checked by a comparative study of two drainage basins in the Precordillera of the Central Andes. In both cases the initial configuration of an incised pediment surface has been restored by using two different methods: the Black Top Hat (BTH) function and the Inverse Distance Weighting (IDW) interpolation. Where vertical incision and hillslope erosion are recorded, the 1DW appears to be the most adequate to reconstitute the pediment surfaces. Conversely, where only vertical incision is observed, the BTH describes more precisely the former pediment surfaces and it is easier to solve. By subtracting the DEM from the reconstructed marker we calculated an eroded volume, and estimated its uncertainty by considering Root Mean Square Error (RMSE) and DEM grid error. For the last similar to 10 Myr we obtained long-term denudation rates of 7.33 +/- 1.6 m/Myr in the San Andres drainage basin and 13.59 +/- 1.9 m/Myr in the El Salado drainage basin. These estimations are largely in agreement with other reported estimates of long-term denudation rates in the Atacama Desert. Comparison with long-term denudation rates reported in a wide range of climatic regimes suggests that our estimates cannot be explained by the current rainfall in the Precordillera. However they could be explained by a rainfall similar to that reported 40 km to the east in the Puna. This suggests that during the time span concerned the geomorphologic evolution of the study area, this evolution is dominated by an orographically controlled rainfall pattern. The preserved pediment surface and the small long term denudation rates determined in this study also indicate that the Precordillera was never reached by humid tropical air masses and precipitation as currently observed in the Altiplano during the summer months

Search for cool giant exoplanets around young and nearby stars - VLT/NaCo near-infrared phase-coronagraphic and differential imaging

[Abridged] Context. Spectral differential imaging (SDI) is part of the observing strategy of current and future high-contrast imaging instruments. It aims to reduce the stellar speckles that prevent the detection of cool planets by using in/out methane-band images. It attenuates the signature of off-axis companions to the star, such as angular differential imaging (ADI). However, this attenuation depends on the spectral properties of the low-mass companions we are searching for. The implications of this particularity on estimating the detection limits have been poorly explored so far. Aims. We perform an imaging survey to search for cool (Teff<1000-1300 K) giant planets at separations as close as 5-10 AU. We also aim to assess the sensitivity limits in SDI data taking the photometric bias into account. This will lead to a better view of the SDI performance. Methods. We observed a selected sample of 16 stars (age < 200 Myr, d < 25 pc) with the phase-mask coronagraph, SDI, and ADI modes of VLT/NaCo. Results. We do not detect any companions. As for the sensitivity limits, we argue that the SDI residual noise cannot be converted into mass limits because it represents a differential flux, unlike the case of single-band images. This results in degeneracies for the mass limits, which may be removed with the use of single-band constraints. We instead employ a method of directly determining the mass limits. The survey is sensitive to cool giant planets beyond 10 AU for 65% and 30 AU for 100% of the sample. Conclusions. For close-in separations, the optimal regime for SDI corresponds to SDI flux ratios >2. According to the BT-Settl model, this translates into Teff<800 K. The methods described here can be applied to the data interpretation of SPHERE. We expect better performance with the dual-band imager IRDIS, thanks to more suitable filter characteristics and better image quality.Comment: 19 pages, 16 figures, accepted for publication in A&A, version including language editin