Dielectric susceptibility of the Coulomb-glass

We derive a microscopic expression for the dielectric susceptibility $\chi$ of a Coulomb glass, which corresponds to the definition used in classical electrodynamics, the derivative of the polarization with respect to the electric field. The fluctuation-dissipation theorem tells us that $\chi$ is a function of the thermal fluctuations of the dipole moment of the system. We calculate $\chi$ numerically for three-dimensional Coulomb glasses as a function of temperature and frequency

Quantum Conductance Steps in Solutions of Multiwalled Carbon Nanotubes

We have prepared solutions of multiwalled carbon nanotubes in Aroclor 1254, a mixture of polychlorinated biphenyls. The solutions are stable at room temperature. Transport measurements were performed using a scanning--tunneling probe on a sample prepared by spin--coating of the solution on gold substrates. Conductance steps were clearly seen. An histogram of a high number of traces shows maximum peaks at integer values of the conductance quantum $G_0 = 2e^2/h$, demonstrating ballistic transport at room temperature along the carbon nanotube over distances longer than $1.4\mu m$.Comment: 4 pages and 2 figure

High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263

We report high spatial resolution i' band imaging of the multiple T Tauri system LkH$\alpha$ 262/LkH$\alpha$ 263 obtained during the first commissioning period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel Telescope, using its Lucky Imaging mode. AOLI images have provided photometry for each of the two components LkH$\alpha$ 263 A and B (0.41 arcsec separation) and marginal evidence for an unresolved binary or a disc in LkH$\alpha$ 262. The AOLI data combined with previously available and newly obtained optical and infrared imaging show that the three components of LkH$\alpha$ 263 are co-moving, that there is orbital motion in the AB pair, and, remarkably, that LkH$\alpha$ 262-263 is a common proper motion system with less than 1 mas/yr relative motion. We argue that this is a likely five-component gravitationally bounded system. According to BT-settl models the mass of each of the five components is close to 0.4 M$_{\odot}$ and the age is in the range 1-2 Myr. The presence of discs in some of the components offers an interesting opportunity to investigate the formation and evolution of discs in the early stages of multiple very low-mass systems. In particular, we provide tentative evidence that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May

Commissioning and First Observations with Wide FastCam at the Telescopio Carlos S\'anchez

The FastCam instrument platform, jointly developed by the IAC and the UPCT, allows, in real-time, acquisition, selection and storage of images with a resolution that reaches the diffraction limit of medium-sized telescopes. FastCam incorporates a specially designed software package to analyse series of tens of thousands of images in parallel with the data acquisition at the telescope. Wide FastCam is a new instrument that, using the same software for data acquisition, does not look for lucky imaging but fast observations in a much larger field of view. Here we describe the commissioning process and first observations with Wide FastCam at the Telescopio Carlos S\'anchez (TCS) in the Observatorio del Teide.Comment: 7 pages, 8 figures, Proc. SPIE. 9908, Ground-based and Airborne Instrumentation for Astronomy VI, 99082O. (August 09, 2016

Numerical modeling of three-dimensional stratified tidal flow over Camarinal Sill, Strait of Gibraltar

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 116 (2011): C12026, doi:10.1029/2011JC007093.The baroclinic response to barotropic tidal forcing in the Camarinal Sill area, within the Strait of Gibraltar, is investigated with a three-dimensional, fully nonlinear, nonhydrostatic numerical model. The aim of numerical efforts was the assessment of three-dimensional effects, which are potentially significant in the area because of rather irregular bottom topography, variable background stratification, and complex structure of barotropic tides. Model results reveal a complex baroclinic response under relatively moderate flood tidal currents, which includes the formation of internal hydraulic jumps upstream of the sill, internal cross waves close to the channel walls, and a plunging pycnocline at the lee side of the sill crest. These structures exhibit significant cross-channel spatial dependence and may appear to be aligned together across the channel. This fact makes their identification difficult from the surface pattern captured by remote sensing images. Under strong barotropic forcing (spring tides) the upstream hydraulic jumps are shifted to the lee side of Camarinal Sill, where a single internal hydraulic jump is formed. Significant first- and second-mode hydraulic jumps are also generated near smaller secondary sills in Tangier basin, thus extending the occurrence of intense water mixing and energy dissipation to other zones of the strait.This work is a contribution to the Spanishfunded National Project INGRES-2 (CTM2006-02326). Partial financial support from Acción Complementaria CTM2009-05810/E (Spanish Ministry of Science and Innovation) and project P08-RNM-3738 from Plan Andaluz de Investigación (Andalucia regional government) is acknowledged.2012-06-1

Expanding the recombinant protein quality in Lactococcus lactis

Background: Escherichia coli has been a main host for the production of recombinant proteins of biomedical interest, but conformational stress responses impose severe bottlenecks that impair the production of soluble, proteolytically stable versions of many protein species. In this context, emerging Generally Recognized As Safe (GRAS) bacterial hosts provide alternatives as cell factories for recombinant protein production, in which limitations associated to the use of Gram-negative microorganisms might result minimized. Among them, Lactic Acid Bacteria and specially Lactococcus lactis are Gram-positive GRAS organisms in which recombinant protein solubility is generically higher and downstream facilitated, when compared to E. coli. However, deep analyses of recombinant protein quality in this system are still required to completely evaluate its performance and potential for improvement. - Results : we have explored here the conformational quality (through specific fluorescence emission) and solubility of an aggregation-prone GFP variant (VP1GFP) produced in L. lactis. In this context, our results show that parameters such as production time, culture conditions and growth temperature have a dramatic impact not only on protein yield, but also on protein solubility and conformational quality, that are particularly favored under fermentative metabolism. - Conclusions: metabolic regime and cultivation temperature greatly influence solubility and conformational quality of an aggregation-prone protein in L. lactis. Specifically, the present study proves that anaerobic growth is the optimal condition for recombinant protein production purposes. Besides, growth temperature plays an important role regulating both protein solubility and conformational quality. Additionally, our results also prove the great versatility for the manipulation of this bacterial system regarding the improvement of functionality, yield and quality of recombinant proteins in this species. These findings not only confirm L. lactis as an excellent producer of recombinant proteins but also reveal room for significant improvement by the exploitation of external protein quality modulators

Relationship between Salmonella infection, shedding and serology in fattening pigs in low–moderate prevalence areas

Salmonella is a major foodborne pathogen causing important zoonosis worldwide. Pigs asymptomatically infected in mesenteric lymph nodes (MLN) can be intermittent shedders of the pathogen through faeces, being considered a major source of human infections. European baseline studies of fattening pig salmonellosis are based on Salmonella detection in MLN. This work studies the relationship between Salmonella infection in MLN and intestinal content (IC) shedding at slaughter and the relationship between the presence of the pathogen and the serologic status at farm level. Mean Salmonella prevalence in the selected pigs (vertically integrated production system of Navarra, Spain) was 7.2% in MLN, 8.4% in IC and 9.6% in serum samples. In this low–moderate prevalence context, poor concordance was found between MLN infection and shedding at slaughter and between bacteriology and serology. In fact, most of shedders were found uninfected in MLN (83%) or carrying different Salmonella strains in MLN and in IC (90%). The most prevalent Salmonellae were Typhimurium resistant to ACSSuT ± Nx or ASSuT antibiotic families, more frequently found invading the MLN (70%) than in IC (33.9%). Multivariable analysis revealed that risk factors associated with the presence of Salmonella in MLN or in IC were different, mainly related either to good hygiene practices or to water and feed control, respectively. Overall, in this prevalence context, detection of Salmonella in MLN is an unreliable predictor of faecal shedding at abattoir, indicating that subclinical infections in fattening pigs MLN could have limited relevance in the IC shedding.info:eu-repo/semantics/acceptedVersio