Universidad del Norte, Colombia

About: Universidad del Norte, Colombia is a education organization based out in Barranquilla, Colombia. It is known for research contribution in the topics: Population & Context (language use). The organization has 3562 authors who have published 4355 publications receiving 37861 citations. The organization is also known as: University of the North, Colombia & Uninorte.

A Shadowing Mitigation Approach for Sea State Parameters Estimation Using X-Band Remotely Sensing Radar Data in Coastal Areas

Abstract: A novel procedure based on filtering and interpolation approaches is proposed to estimate the sea state parameters, including significant wave height, peak wave direction, peak period, peak wavenumber, and peak wavelength in shallow waters using the X-band marine radars. The method compensates the distortions introduced by the radar acquisition process and the power decay of the radar signal along the distance applying image-enhancement techniques instead of empirical and semiempirical calibration methods that use signal-to-noise ratio and in situ measurements as external references. To determine the threshold value for the interpolation approach, the influence of the antenna height on shadowing modulation effects is examined through performing an analysis of variance (ANOVA) that uses data from two X-band radars deployed at 10 and 20 m above MSL. ANOVA results reveal that it is possible to explain the increment of intensities affected by shadowing throughout the distance using an adaptive threshold retrieved from a third-order polynomial function of the mean radar cross section (RCS). Finally, an X-band radar is installed at 13 m above MSL to test the proposed technique. During measurements, the wind and wave conditions varied, and the antenna-look direction remained constant. Errors for $H_{s}$ , $\theta _{p}$ , and $T_{p}$ calculated as the difference between estimated and true data show a mean bias and a relative value of 0.05 m (2.72%), 1.52° (5.94%), and 0.15 s (1.67%), respectively. The directional and wave energy spectra derived from radar estimates, acoustic wave and current, ADVs record, as well as JONSWAP formulation are presented to illustrate the improvement resulting from the proposed method over the frequency domain.

Characterization of treatment failure in HIV positive patients in the Colombian Caribbean region.

Abstract: Objectives: Treatment failure in patients receiving antiretroviral therapy against human immunodeficiency virus (HIV) is always a concern. The major aim of the present work was to examine the correlates associated with treatment failure in patients living in the Colombian Caribbean city of Barranquilla, an aspect that was poorly studied in this region. Methods: Treatment failure was evaluated in a cross-sectional study from virological, immunological and clinical standpoints. Results: It was established that 29.5% of patients under highly active antiretroviral therapy (HAART) could be considered in treatment failure. Among those, virological failure was most frequent (20.9%), followed by immunological- (14.0%) and clinical failure (4.7%). In patients showing lack of adherence to the treatment, the likelihood of suffering from treatment- and virogical-failure were respectively increased by 6.67-fold and 12.19-fold, compared with patients showing good adherence. Although there was no statistically significant association, treatment failure tended to be more frequent in young adults and in patients with low income or low level of education. When antiretroviral therapies (ART) regimens were compared, there was no apparent difference in treatment failure between regimens based on non-nucleoside reverse transcriptase inhibitors and those based on protease inhibitors. This is very important in the context of recent ART strategies, such as early-initiated ART, aimed at achieving long-term infection control. Conclusions: The current study confirms the importance of treatment adherence to avoid treatment failure and further highlights the importance of educating HIV-infected patients in all parts of the world, especially those individuals with a lower socio-economic status.

Use of synthetic peptides to represent surface-exposed epitopes defined by neutralizing dengue complex- and flavivirus group-reactive monoclonal antibodies on the native dengue type-2 virus envelope glycoprotein.

Abstract: The reactions of neutralizing monoclonal antibodies (mAbs) that defined dengue virus (DENV) complex, flavivirus subgroup or group neutralizing epitopes were tested against synthetic peptide sequences from domains I, II and III of the envelope (E) glycoproteins of different DENV-2 genotypes/strains. The DENV complex-reactive mAb identified the surface-exposed 304-GKFKV/IVKEIA-313 peptides and the DENV complex-conserved 393-KKGSSIGQ/KM-401 peptides in domain III, which were located adjacently in the native glycoprotein. Both flavivirus group-reactive mAbs reacted most strongly with fusion sequence peptides from domain II when they contained a cysteine (C) by glycine (G) substitution (underlined) (101-WGNGGGLFG-109) to represent the native rotated C side chain. The 393–401 sequence represents a newly identified epitope, present as a highly flexible coil located between the 385 and 393 cell-binding sequence and the 401 and 413 sequence involved in the E glycoprotein homo-trimer formation. The 101–109 sequence containing 105-C by G substitution and the 393–401 sequence are good candidates for diagnostic assays and cross-protection experiments.