A covert attention P300-based brain-computer interface: Geospell

The Farwell and Donchin P300 speller interface is one of the most widely used brain-computer interface (BCI) paradigms for writing text. Recent studies have shown that the recognition accuracy of the P300 speller decreases significantly when eye movement is impaired. This report introduces the GeoSpell interface (Geometric Speller), which implements a stimulation framework for a P300-based BCI that has been optimised for operation in covert visual attention. We compared the Geospell with the P300 speller interface under overt attention conditions with regard to effectiveness, efficiency and user satisfaction. Ten healthy subjects participated in the study. The performance of the GeoSpell interface in covert attention was comparable with that of the P300 speller in overt attention. As expected, the effectiveness of the spelling decreased with the new interface in covert attention. The NASA task load index (TLX) for workload assessment did not differ significantly between the two modalities. PRACTITIONER SUMMARY: This study introduces and evaluates a gaze-independent, P300-based brain-computer interface, the efficacy and user satisfaction of which were comparable with those off the classical P300 speller. Despite a decrease in effectiveness due to the use of covert attention, the performance of the GeoSpell far exceeded the threshold of accuracy with regard to effective spelling.     

Turning a Digital Camera into an Absolute 2D Tele‐Colorimeter

We present a simple and effective technique for absolute colorimetric camera characterization, invariant to changes in exposure/aperture and scene irradiance, suitable in a wide range of applications including image‐based reflectance measurements, spectral pre‐filtering and spectral upsampling for rendering, to improve colour accuracy in high dynamic range imaging. Our method requires a limited number of acquisitions, an off‐the‐shelf target and a commonly available projector, used as a controllable light source, other than the reflected radiance to be known. The characterized camera can be effectively used as a 2D tele‐colorimeter, providing the user with an accurate estimate of the distribution of luminance and chromaticity in a scene, without requiring explicit knowledge of the incident lighting power spectra. We validate the approach by comparing our estimated absolute tristimulus values (XYZ data in ) with the measurements of a professional 2D tele‐colorimeter, for a set of scenes with complex geometry, spatially varying reflectance and light sources with very different spectral power distribution.     

Change in the publishing regime in Latin America: from a local to universal journal,Archivos de investigación Médica/Archives of Medical Research (1970–2014)

This study addresses an early case of an association between a local journal and a commercial publisher in Latin America striving to improve quality. The two journals examined are Archivos de Investigación Médica (AIM), 1970–1991 and its continuation as Archives of Medical Research (AMR), 1992–2014. The aim is to characterize and compare the publishing policies and patterns of scientific communication and bibliometric indicators developed under the two different types of publication: AIM as a source of local dissemination and the commercially circulated AMR. Publishing policies, production, and citations were identified in accordance with coverage by the Web of Science and Scopus indexes. The papers and citations were grouped into three categories according to the author´s affiliation: local, regional, and external. This categorization resulted in different combinations of correlations between cited and citing papers, in addition to a distribution of collaborative production and citations by country organized by continent. The comparison of results reveals two successful publishing projects; however, editorial practices pose an irreconcilable situation between the AIM objectives as a regional journal and AMR objectives as a mainstream journal, according with dominant indicators of international competition. Some implications of this situation are discussed in the context of Latin American and Caribbean journals.     

Diverticula of the female urethra

OBJECTIVES: The contribution of ultrasonography to pretreatment morphological assessment of strictures of the anterior urethra and assessment of the risk of recurrence after internal urethrotomy. MATERIAL AND METHODS: 33 patients (16-89 years) operated by internal urethrotomy for stricture of the anterior urethra and followed for at least 6 months. Preoperative urethral ultrasonography, recording the number, length and degree of strictures and echostructure of the peristenotic fibrosis of the corpus spongiosium. RESULTS: Ultrasound visualization of all urethral strictures, with no false-positives and no false-negatives. 11 patients relapsed after a mean interval of 5.7 months (1-16 months), 22 patients did not present recurrence: mean interval: 15.5 months (6-36 months). Corpus spongiosum fibrosis associated with urethral stricture is isoechoic to the corpus spongiosum (19 cases) or hyperechoic to the corpus spongiosum (14 cases). No statistical correlation was observed between the echostructure of the fibrous tissue and the risk of recurrence after internal urethrotomy. CONCLUSION: Ultrasonography allows excellent analysis of the morphological characteristics of a stricture of the male anterior urethra. In our experience, and in contrast with the limited data of the literature, no correlation was observed between the echostructure of the peristenotic fibrosis and the risk of recurrence after internal urethrotomy.     

Improved quadrature formulas for boundary integral equations with conducting or dielectric edge singularities

In this paper we derive new two-dimensional (2-D) quadrature formulas for the discretization of boundary integral equations in the presence of conducting or dielectric edges. The proposed formulas allow us to exactly integrate polynomials of degree less than or equal to five, multiplied by an algebraic singular factor that diverges along one side of the triangular integration domain. This is the kind of singularity that occurs when physical edges are present in both conducting and dielectric bodies. Numerical tests are performed on the presented formulas, in order to validate the achieved improvement in accuracy, and examples are given of their application to the determination of radar cross-section of 3-D metallic objects.     

Reflections on the institutionalization process of scientific research in Latin America: the case of Cinvestav

Scientometrics - Consolidation of the scientific activity in Latin American research centers has been a matter of serious concern in recent years. In the present study we use a data set of the WoS...     

Bacterial lipopolysaccharide increases interleukin-6 and prostaglandin release in rat cortical type I astrocytes by different mechanisms: role of anti-inflammatory agents

LPS stimulated IL-6 release in a concentration-dependent manner from rat cortical type I astrocytes. This stimulatory action was completely abolished by Dexamethasone (DEX), but was not affected by indomethacin (IND), a 5-cyclooxigenase inhibitor. LPS-induced IL-6 release was partially inhibited by BW 4AC, a 5-lipoxygenase inhibitor. LPS concentration-dependently increased the release of PGE2 from type I astrocytes, an effect completely inhibited by IND. To rule out the possibility that DEX was inhibiting LPS-induced IL-6 release by blocking IL-6 gene expression, we tested the effect of DEX on interleukin 1beta(IL-1)-induced IL-6 release. DEX slightly inhibited IL-1-induced IL-6 release, while IL-1 releasing action on IL-6 was significantly reduced by IND. The involvement of nitric oxide (NO) generation on LPS-induced IL-6 release was also studied. We found that L-NO-arginine, an inhibitor of nitric oxide synthase, concentration-dependently reduced LPS-induced IL-6 release in astrocytes. In conclusion, we provide evidence that LPS action on IL-6 and PGE2 release can be ascribed to the activation of different transduction mechanisms, which can be pharmacologically dissected with the aid of anti-inflammatory drugs.     

Color space transformations for digital photography exploiting information about the illuminant estimation process

The color reproduction accuracy is a key factor to the overall perceived image quality in digital photography. In this framework, both the illuminant estimation process and the color correction matrix concur in the formation of the overall perceived image quality. To the best of our knowledge, the two processes have always been studied separately, thus ignoring the interactions between them. We investigate here these interactions, showing how the color correction transform amplifies the illuminant estimation errors. We demonstrate that incorporating knowledge about the illuminant estimation behavior in the optimization of the color correction matrix makes it possible to alleviate the error amplification. Different strategies to improve color accuracy under both perfect and imperfect white point estimations are investigated, and the experimental results obtained with a digital camera simulator are reported.     

Opposite roles of apolipoprotein E in normal brains and in Alzheimer's disease

We have characterized the interaction between apolipoprotein E (apoE) and amyloid beta peptide (Abeta) in the soluble fraction of the cerebral cortex of Alzheimer's disease (AD) and control subjects. Western blot analysis with specific antibodies identified in both groups a complex composed of the full-length apoE and Abeta peptides ending at residues 40 and 42. The apoE-Abeta soluble aggregate is less stable in AD brains than in controls, when treated with the anionic detergent SDS. The complex is present in significantly higher quantity in control than in AD brains, whereas in the insoluble fraction an inverse correlation has previously been reported. Moreover, in the AD subjects the Abeta bound to apoE is more sensitive to protease digestion than is the unbound Abeta. Taken together, our results indicate that in normal brains apoE efficiently binds and sequesters Abeta, preventing its aggregation. In AD, the impaired apoE-Abeta binding leads to the critical accumulation of Abeta, facilitating plaque formation.