The discrete-time parabolic Anderson model with heavy-tailed potential

We consider a discrete-time version of the parabolic Anderson model. This may be described as a model for a directed (1+d)-dimensional polymer interacting with a random potential, which is constant in the deterministic direction and i.i.d. in the d orthogonal directions. The potential at each site is a positive random variable with a polynomial tail at infinity. We show that, as the size of the system diverges, the polymer extremity is localized almost surely at one single point which grows ballistically. We give an explicit characterization of the localization point and of the typical paths of the model.Comment: 32 page

First results of a GNSS-R experiment from a stratospheric balloon over boreal forests

The empirical results of a global navigation satellite systems reflectometry (GNSS-R) experiment onboard the Balloon EXperiments for University Students (BEXUS) 17 stratospheric balloon performed north of Sweden over boreal forests show that the power of the reflected signals is nearly independent of the platform height for a high coherent integration time T-c = 20 ms. This experimental evidence shows a strong coherent component in the forward scattered signal, as compared with the incoherent component, that allows to be tracked. The bistatic coherent reflectivity is also evaluated as a function of the elevation angle, showing a decrease of similar to 6 dB when the elevation angle increases from 35. to 70 degrees. The received power presents a clearly multimodal behavior, which also suggests that the coherent scattering component may be taking place in different forest elements, i.e., soil, canopy, and through multiple reflections canopy-soil and soil-trunk. This experiment has provided the first GNSS-R data set over boreal forests. The evaluation of these results can be useful for the feasibility study of this technique to perform biomass monitoring that is a key factor to analyze the carbon cycle.Peer ReviewedPostprint (author's final draft

Impact of monotherapy on HIV-1 reservoir, immune activation, and co-infection with Epstein-Barr virus

Abstract Objectives Although monotherapy (mART) effectiveness in maintaining viral suppression and CD4 cell count has been extensively examined in HIV-1-infected patients, its impact on HIV-1 reservoir, immune activation, microbial translocation and co-infection with Epstein-Barr Virus (EBV) is unclear. Methods This retrospective study involved 32 patients who switched to mART; patients were studied at baseline, 48 and 96 weeks after mART initiation. Thirty-two patients who continued combined antiretroviral therapy (cART) over the same period of time were included in the study. Markers of HIV-1 reservoir (HIV-1 DNA and intracellular HIV-1 RNA) were quantified by real-time PCR. Markers of T-(CD3(+)CD8(+)CD38(+)) and B-(CD19(+)CD80/86(+) and CD19(+)CD10-CD21(low)CD27(+)) cell activation were evaluated by flow cytometry. Plasma levels of microbial translocation markers were quantified by real-time PCR (16S ribosomal DNA and mitochondrial [mt] DNA) or by ELISA (LPS and sCD14). EBV was typed and quantified by multiplex real-time PCR. Results At baseline, no differences were found between mART and cART groups. Three (10%) mART-treated patients had a virological failure vs none in the cART group. Levels of HIV-1 DNA, intracellular HIV-1 RNA and EBV-DNA remained stable in the mART group, while decreased significantly in the cART group. Percentages of T-and B-activated cells significantly increased in the mART-treated patients, while remained at low levels in the cART-treated ones (p = 0.014 and p<0.001, respectively). Notably, levels of mtDNA remained stable in the cART group, but significantly rose in the mART one (p<0.001). Conclusions Long-term mART is associated with higher levels of T-and B-cell activation and, conversely to cART, does not reduce the size of HIV-1 reservoir and EBV co-infection

MERITXELL: the Multifrequency Experimental Radiometer with Interference Tracking for Experiments over Land and Littoral—instrument description, calibration and performance

MERITXELL is a ground-based multisensor instrument that includes a multiband dual-polarization radiometer, a GNSS reflectometer, and several optical sensors. Its main goals are twofold: to test data fusion techniques, and to develop Radio-Frequency Interference (RFI) detection, localization and mitigation techniques. The former is necessary to retrieve complementary data useful to develop geophysical models with improved accuracy, whereas the latter aims at solving one of the most important problems of microwave radiometry. This paper describes the hardware design, the instrument control architecture, the calibration of the radiometer, and several captures of RFI signals taken with MERITXELL in urban environment. The multiband radiometer has a dual linear polarization total-power radiometer topology, and it covers the L-, S-, C-, X-, K-, Ka-, and W-band. Its back-end stage is based on a spectrum analyzer structure which allows to perform real-time signal processing, while the rest of the sensors are controlled by a host computer where the off-line processing takes place. The calibration of the radiometer is performed using the hot-cold load procedure, together with the tipping curves technique in the case of the five upper frequency bands. Finally, some captures of RFI signals are shown for most of the radiometric bands under analysis, which evidence the problem of RFI in microwave radiometry, and the limitations they impose in external calibration.Peer ReviewedPostprint (published version

Immune senescence and immune activation in elderly colorectal cancer patients

In our previous study, we found that low thymic output and short telomere length were associated with a higher risk of tumor in elderly cancer patients. Here, we aimed to examine in depth the impact of immunological and biological senescence and immune activation on disease outcome in elderly patients with colorectal cancer (CRC).Peripheral blood samples from 81 CRC patients were studied for immune activation, immune senescence and recent thymic emigrant (RTE) CD4 and CD8 cells by flow cytometry. T-cell receptor rearrangement excision circle (TREC) levels and telomere lengths were measured by real-time PCR. Plasma levels of microbial translocation markers, LPS and sCD14, were quantified by ELISA. While TREC levels and telomere length were not prognostic of disease outcome, high percentages of immune senescent and immune activated CD8 cells were associated with a higher risk of a negative event (relapse, progression, or death) in all studied patients and disease relapse in I-Ill staged patients. Levels of sCD14 and LPS were higher in patients who will experience a negative event than in patients who will not. In conclusion, in elderly CRC patients higher immunological senescence and immune activation negatively impact the disease outcome; how these characteristics influence the antineoplastic treatments remains to be investigated

The critical equation of state of the three-dimensional O(N) universality class: N>4

We determine the scaling equation of state of the three-dimensional O(N) universality class, for N=5, 6, 32, 64. The N=5 model is relevant for the SO(5) theory of high-T_c superconductivity, while the N=6 model is relevant for the chiral phase transition in two-color QCD with two flavors. We first obtain the critical exponents and the small-field, high-temperature, expansion of the effective potential (Helmholtz free energy) by analyzing the available perturbative series, in both fixed-dimension and epsilon-expansion schemes. Then, we determine the critical equation of state by using a systematic approximation scheme, based on polynomial representations valid in the whole critical region, which satisfy the known analytical properties of the equation of state, take into account the Goldstone singularities at the coexistence curve and match the small-field, high-temperature, expansion of the effective potential. This allows us also to determine several universal amplitude ratios. We also compare our approximate solutions with those obtained in the large-N expansion, up to order 1/N, finding good agreement for N\gtrsim 32.Comment: 27 pages, 8 figures. v2: Improved presentation, updated references. Nucl. Phys. B in pres