Vision-Based Autonomous Underwater Vehicle Navigation in Poor Visibility Conditions Using a Model-Free Robust Control

This paper presents a vision-based navigation system for an autonomous underwater vehicle in semistructured environments with poor visibility. In terrestrial and aerial applications, the use of visual systems mounted in robotic platforms as a control sensor feedback is commonplace. However, robotic vision-based tasks for underwater applications are still not widely considered as the images captured in this type of environments tend to be blurred and/or color depleted. To tackle this problem, we have adapted the lαβ color space to identify features of interest in underwater images even in extreme visibility conditions. To guarantee the stability of the vehicle at all times, a model-free robust control is used. We have validated the performance of our visual navigation system in real environments showing the feasibility of our approach

Cold-adaptation of a methacrylamide gelatin towards the expansion of the biomaterial toolbox for specialized functionalities in tissue engineering

© 2019 Elsevier B.V.Tissue regeneration is witnessing a significant surge in advanced medicine. It requires the interaction of scaffolds with different cell types for efficient tissue formation post-implantation. The presence of tissue subtypes in more complex organs demands the co-existence of different biomaterials showing different hydrolysis rate for specialized cell-dependent remodeling. To expand the available toolbox of biomaterials with sufficient mechanical strength and variable rate of enzymatic degradation, a cold-adapted methacrylamide gelatin was developed from salmon skin. Compared with mammalian methacrylamide gelatin (GelMA), hydrogels derived from salmon GelMA displayed similar mechanical properties than the former. Nevertheless, salmon gelatin and salmon GelMA-derived hydrogels presented characteristics common of cold-adaptation, such as reduced activation energy for collagenase, increased enzymatic hydrolysis turnover of hydrogels, increased interconnected polypepti

From outburst to quiescence: Spectroscopic evolution of V1838 Aql imbedded in a bow-shock nebula

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We analyse new optical spectroscopic, direct-image and X-ray observations of the recently discovered a high-proper motion cataclysmic variable V1838 Aql. The data were obtained during its 2013 superoutburst and its subsequent quiescent state. An extended emission around the source was observed up to 30 d after the peak of the superoutburst, interpreted it as a bow shock formed by a quasi-continuous outflow from the source in quiescence. The head of the bow shock is coincident with the high-proper motion vector of the source (v⊥ = 123 ± 5 km s-1) at a distance of d = 202 ± 7 pc. The object was detected as a weak X-ray source (0.015 ± 0.002 counts s-1) in the plateau of the superoutburst and its flux lowered by two times in quiescence (0.007 ± 0.002 counts s-1). Spectroscopic observations in quiescence we confirmed the orbital period value Porb = 0.0545 ± 0.0026 d, consistent with early-superhump estimates, and the following orbital parameters: γ = -21 ± 3 km s-1 and K1 = 53 ± 3 km s-1. The white dwarf is revealed as the system approaches quiescence, which enables us to infer the effective temperature of the primary Teff = 11 600 ± 400 K. The donor temperature is estimated ≲2200K and suggestive of a system approaching the period minimum. Doppler maps in quiescence show the presence of the hotspot in He I line at the expected accretion disc-stream shock position and an unusual structure of the accretion disc in Hα

From outburst to quiescence: Spectroscopic evolution of V1838 Aql imbedded in a bow-shock nebula

© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. We analyse new optical spectroscopic, direct-image and X-ray observations of the recently discovered a high-proper motion cataclysmic variable V1838 Aql. The data were obtained during its 2013 superoutburst and its subsequent quiescent state. An extended emission around the source was observed up to 30 d after the peak of the superoutburst, interpreted it as a bow shock formed by a quasi-continuous outflow from the source in quiescence. The head of the bow shock is coincident with the high-proper motion vector of the source (v⊥ = 123 ± 5 km s-1) at a distance of d = 202 ± 7 pc. The object was detected as a weak X-ray source (0.015 ± 0.002 counts s-1) in the plateau of the superoutburst and its flux lowered by two times in quiescence (0.007 ± 0.002 counts s-1). Spectroscopic observations in quiescence we confirmed the orbital period value Porb = 0.0545 ± 0.0026 d, consistent with early-superhump estimates, and the following orbital parameters: γ = -21 ± 3 km s-1 and K1 = 53 ± 3 km s-1. The white dwarf is revealed as the system approaches quiescence, which enables us to infer the effective temperature of the primary Teff = 11 600 ± 400 K. The donor temperature is estimated ≲2200K and suggestive of a system approaching the period minimum. Doppler maps in quiescence show the presence of the hotspot in He I line at the expected accretion disc-stream shock position and an unusual structure of the accretion disc in Hα

From outburst to quiescence:spectroscopic evolution of V1838 Aql imbedded in a bow-shock nebula

We analyse new optical spectroscopic, direct-image and X-ray observations of the recently discovered a high-proper motion cataclysmic variable V1838 Aql. The data were obtained during its 2013 superoutburst and its subsequent quiescent state. An extended emission around the source was observed up to 30 d after the peak of the superoutburst, interpreted it as a bow shock formed by a quasi-continuous outflow from the source in quiescence. The head of the bow shock is coincident with the high-proper motion vector of the source (v⊥ = 123 ± 5 km s−1) at a distance of d = 202 ± 7 pc. The object was detected as a weak X-ray source (0.015 ± 0.002 counts s−1) in the plateau of the superoutburst and its flux lowered by two times in quiescence (0.007 ± 0.002 count s-1). Spectroscopic observations in quiescence we confirmed the orbital period value Porb = 0.0545 ± 0.0026 d, consistent with early-superhump estimates, and the following orbital parameters: γ = −21 ± 3 km s−1 and K1 = 53 ± 3 km s−1. The white dwarf is revealed as the system approaches quiescence, which enables us to infer the effective temperature of the primary Teff = 11 600 ± 400 K. The donor temperature is estimated ≲2200 K and suggestive of a system approaching the period minimum. Doppler maps in quiescence show the presence of the hotspot in He i line at the expected accretion disc-stream shock position and an unusual structure of the accretion disc in Hα

From outburst to quiescence:spectroscopic evolution of V1838 Aql imbedded in a bow-shock nebula

Abstract We analyse new optical spectroscopic, direct-image and X-ray observations of the recently discovered a high-proper motion cataclysmic variable V1838 Aql. The data were obtained during its 2013 superoutburst and its subsequent quiescent state. An extended emission around the source was observed up to 30 d after the peak of the superoutburst, interpreted it as a bow shock formed by a quasi-continuous outflow from the source in quiescence. The head of the bow shock is coincident with the high-proper motion vector of the source (v⊥ = 123 ± 5 km s⁻¹) at a distance of d = 202 ± 7 pc. The object was detected as a weak X-ray source (0.015 ± 0.002 counts s⁻¹) in the plateau of the superoutburst and its flux lowered by two times in quiescence (0.007 ± 0.002 counts s⁻¹). Spectroscopic observations in quiescence we confirmed the orbital period value Porb = 0.0545 ± 0.0026 d, consistent with early-superhump estimates, and the following orbital parameters: γ = −21 ± 3 km s−1 and K₁ = 53 ± 3 km s⁻¹. The white dwarf is revealed as the system approaches quiescence, which enables us to infer the effective temperature of the primary Teff = 11 600 ± 400 K. The donor temperature is estimated ≲2200 K and suggestive of a system approaching the period minimum. Doppler maps in quiescence show the presence of the hotspot in He i line at the expected accretion disc-stream shock position and an unusual structure of the accretion disc in Hα

New Findings in eNOS gene and Thalidomide Embryopathy Suggest pre-transcriptional effect variants as susceptibility factors

Antiangiogenic properties of thalidomide have created an interest in the use of the drug in treatment of cancer. However, thalidomide is responsible for thalidomide embryopathy (TE). A lack of knowledge regarding the mechanisms of thalidomide teratogenesis acts as a barrier in the aim to synthesize a safer analogue of thalidomide. Recently, our group detected a higher frequency of alleles that impair the pro-angiogenic mechanisms of endothelial nitric oxide synthase (eNOS), coded by the NOS3 gene. In this study we evaluated variable number tandem repeats (VNTR) functional polymorphism in intron 4 of NOS3 in individuals with TE (38) and Brazilians without congenital anomalies (136). Haplotypes were estimated for this VNTR with previously analyzed polymorphisms, rs2070744 (−786C > T) and rs1799983 (894T > G), in promoter region and exon 7, respectively. Haplotypic distribution was different between the groups (p = 0.007). Alleles −786C (rs2070744) and 4b (VNTR), associated with decreased NOS3 expression, presented in higher frequency in TE individuals (p = 0.018; OR = 2.57; IC = 1.2–5.8). This association was not identified with polymorphism 894T > G (p = 0.079), which influences eNOS enzymatic activity. These results suggest variants in NOS3, with pre-transcriptional effects as susceptibility factors, influencing the risk TE development. This finding generates insight for a new approach to research that pursues a safer analogue