The Enigma of the Dark Matter

One of the great scientific enigmas still unsolved, the existence of dark matter, is reviewed. Simple gravitational arguments imply that most of the mass in the Universe, at least 90%, is some (unknown) non-luminous matter. Some particle candidates for dark matter are discussed with particular emphasis on the neutralino, a particle predicted by the supersymmetric extension of the Standard Model of particle physics. Experiments searching for these relic particles, carried out by many groups around the world, are also discussed. These experiments are becoming more sensitive every year and in fact one of the collaborations claims that the first direct evidence for dark matter has already been observed.Comment: Invited review article for the journal Contemporary Physics. The level is suitable for researchers which are non-specialists in the subject, and also for students. Latex, 20 pages, 5 figure

Genes y variantes polimórficas asociadas a la enfermedad cardiovascular

ResumenLa aterosclerosis se considera como la principal causante de enfermedades cardiovasculares. Es una enfermedad multifactorial, caracterizada por procesos inflamatorios y la internalización continua de moléculas lipídicas al interior del vaso. Los estudios de genes candidato han proporcionado conocimiento acerca de la fisiopatología de esta enfermedad y han permitido la postulación de algunos polimorfismos como responsables de la susceptibilidad genética en diversas poblaciones. En particular, estos polimorfismos que modulan ciertas vías moleculares tales como el estrés oxidativo, el metabolismo lipídico y la trombogénesis se asocian con el desarrollo de las enfermedades cardiovasculares. Se han conducido varios estudios para identificar nuevas variantes asociadas con la enfermedad que han permitido el descubrimiento de nuevas vías de la enfermedad. Aunque el hallazgo de nuevos genes asociados a la enfermedad cardiovascular a través de enfoques como el escaneo global del genoma ha contribuido al entendimiento del desarrollo de esta condición, el conocimiento aún es limitado y poco concluyente. El objetivo de esta revisión es identificar los genes y las variantes polimórficas asociadas a la enfermedad cardiovascular, de acuerdo con los diferentes enfoques de análisis de asociación genética.AbstractAtherosclerosis is considered the main cause of cardiovascular diseases. This is a multifactorial disease, characterized by inflammatory processes and the continuous internalization of lipid molecules into the blood vessel. Candidate gene studies have provided knowledge on the pathophysiology of this disease and have allowed postulating some polymorphisms as responsible for the genetic susceptibility in several populations. In particular, these polymorphisms that modulate certain molecular pathways such as oxidative stress, lipid metabolism and thrombogenesis are associated to the development of cardiovascular diseases. Several studies have been used to identify new variants associated with the disease enabling the discovery of new disease pathways. Although the discovery of novel genes associated with cardiovascular disease through approaches such as global scan of the genome has contributed to understanding the development of this disease, knowledge is still limited and inconclusive. The aim of this review is to identify genes and polymorphic variants associated with cardiovascular disease, according to the different approaches of genetic association analysis

Intraspecific genomic divergence and minor structural variations in leishmania (Viannia) panamensis

Leishmania (Viannia) panamensis is one of the most important Leishmania species associated with cutaneous leishmaniasis (CL) in Latin America. Despite its wide geographic distribution and pathogenic potential in humans and animals, the genomic variability of this species is low compared with other Leishmania species circulating in the same geographical area. No studies have reported a detailed analysis of the whole genome of L. panamensis from clinical isolates using DNA highthroughput sequencing to clarify its intraspecific genomic variability or plausible divergence. Therefore, this study aimed to evaluate the intraspecific genomic variability of L. panamensis from Colombia and Panama. A total of 22 genomes were analyzed, 19 from Colombian patients with CL and three genomes from Panama obtained from public databases. The phylogenomic analysis revealed the potential existence of three well-supported clades as evidence of intraspecific divergence. Additionally, the whole-genome analysis showed low structural variations in terms of ploidy, copy number variations, and single-nucleotide polymorphisms (SNPs). SNPs shared among all clades were identified, revealing their importance in different biological processes of L. panamensis. The findings not only expand our knowledge of intraspecific genomic variability of one of the most important Leishmania species in South America but also highlights the possible existence of different clades/lineages/subpopulations across a geographic scale. © 2020 by the authors. Licensee MDPI, Basel, Switzerland

Vigor hibrido y habilidad combinatoria en variedades comerciales y líneas de arroz (oryza sativa l.) de colombia

Entre las variedades Cica-4, Cica-7, Oryzica-1, Oryzica-2 y las líneas experimentales 17396 y 11744, se realizó un cruzamiento dialélico, sin sus recíprocos. El diseño empleado fue bloques al azar con cuatro repeticiones. Una planta por sitio se trasplantó a los 29 y 30 días en parcelas de tres metros de longitud y 90 centímetros de ancho, con un total de 60 plantas. La distancia desiembra fue de 30x20 cm. El mayor valor heterótico respecto al promedio y mejor parental en rendimiento se presentaron en el híbridoOryzica-2 x Cica- 4 (144.12 Y 139.42 %), el cual rindió 8_5 t/ha. La heterosis para rendimiento fue mayor que la de sus componentes. El índice de área foliar y número de granos por panícula contribuyeron positiva y significativamente en el rendimiento de los híbridos; mientras que tallos efectivos por planta es el contribuyente principal en el rendimiento de los padres. En la variación entre genotipos para rendimiento, eso y número de granos por panicula participaron efectos de HCE y para peso de 1000 granos y tallos efectivos participaron efectos de HCG. La heterosis en rendimiento, granos por panícula y peso de 1000 granos se asociaron con efectos de HCE.A diallel cross without their reciprocals was made between varieties Cica-4, Cica- 7, Oryzica-l, Oryzica-2 and the experimental lines 17396 and 11744. The experimental design was the randomized block with four replications. A plant per site was transplanted at the 29-30 days in 3 meters by 90 centimeters plots with a total of 60 plants. The planting distances were 30 cm x 20 cm. The higher heterotic value with respect to the mid-parent and the better parent for yield was shOlM1by the hybrid Oryzica- 2 x Cica-4 (144.12 % and 139.42 olo), which yielded 8_5 t/ha. The heterosis for yield was greater thouse of there components. Leaf index and number of grains per panicle contribute positive and significantly at the yield of the hybrids while effective tillers per plant were the main contribute at the parents yield. In the variation between genotypes for yield, weight and number of grains per panicle sea effects participated and for weight 1000 grains and effective tillers gca effects participated The heterosis for yield, grains per panicle and weight 1000 grains showea association with sea effects

Tailoring Organic-Organic Poly(vinylpyrrolidone) Microparticles and Fibers with Multiwalled Carbon Nanotubes for Reinforced Composites

Polymeric-based microparticles and fibers are tailorable for a wide range of common industrial and biomedical applications, while multiwalled carbon nanotubes (MWCNTs) are among the most useful macromolecules based on their outstanding electronic, mechanical, and optical properties at the nanoscale. If one combines these nanostructures with various polymeric precursors, their range of potential applications becomes even greater. One of the simplest and most affordable methods for fabricating micro- and nanostructures is electrospinning. Herein we demonstrate how MWCNTs may be used to produce tailor-made organic-organic poly(vinylpyrrolidone) (PVP) microparticles and fibers via electrospinning by studying their structural, vibrational, rheological, and mechanical properties' dependence on their solvent (ethanol (EtOH) or dimethylformamide (DMF)) and resulting morphology. Specifically, we find clear differences in morphologies from perfectly spherical and isolated microparticles to fibers mats, or a combination of fibers with entangled beads, with solvent type and concentration. On the basis of our findings, we propose that the mechanism governing the shape and size of the particles is a competition between the solvent's surface tension, dielectric constant, and viscoelastic properties. We show, based on both our experimental results and density functional theory (DFT) calculations, that OH functionalization of the MWCNTs is essential for achieving high PVP coverages and promoting the stability of the resulting PVP/MWCNT nanocomposite. Finally, by fabricating PVP/MWCNT fiber mats, we demonstrate that low concentrations (0.01-0.1 wt %) of MWCNTs led to a qualitative improvement (â250%) in the resulting mechanical properties, i.e., a reinforced composite. These results show how by controlling the solvent's dielectric constant, surface tension, and polymer concentration, one may produce tailor-made polymeric nanomaterials in combination with other organic/inorganic nanoparticles, i.e., silver, gold, or carbon allotropes, for next-generation applications

The GALEX/S4G UV-IR color-color diagram: Catching spiral galaxies away from the Blue Sequence

We obtained GALEX FUV, NUV, and Spitzer/IRAC 3.6$\mu$m photometry for > 2000 galaxies, available for 90% of the S4G sample. We find a very tight "GALEX Blue Sequence (GBS)" in the (FUV-NUV) versus (NUV-[3.6]) color-color diagram which is populated by irregular and spiral galaxies, and is mainly driven by changes in the formation timescale ($\tau$) and a degeneracy between $\tau$ and dust reddening. The tightness of the GBS provides an unprecedented way of identifying star-forming galaxies and objects that are just evolving to (or from) what we call the "GALEX Green Valley (GGV)". At the red end of the GBS, at (NUV-[3.6]) > 5, we find a wider "GALEX Red Sequence (GRS)" mostly populated by E/S0 galaxies that has a perpendicular slope to that of the GBS and of the optical red sequence. We find no such dichotomy in terms of stellar mass (measured by $\rm{M}_{[3.6]}$), since both massive ($M_{\star} > 10^{11} M_{\odot}$) blue and red sequence galaxies are identified. The type that is proportionally more often found in the GGV are the S0-Sa's and most of these are located in high-density environments. We discuss evolutionary models of galaxies that show a rapid transition from the blue to the red sequence on timescale of $10^{8}$years.Comment: 7 pages, 4 figures, 1 table. Accepted for publication in ApJ

Halpha Kinematics of S4G Spiral Galaxies - III. Inner rotation curves

We present a detailed study of the shape of the innermost part of the rotation curves of a sample of 29 nearby spiral galaxies, based on high angular and spectral resolution kinematic Halpha Fabry-Perot observations. In particular, we quantify the steepness of the rotation curve by measuring its slope dRvc(0). We explore the relationship between the inner slope and several galaxy parameters, such as stellar mass, maximum rotational velocity, central surface brightness ({\mu}0), bar strength and bulge-to-total ratio. Even with our limited dynamical range, we find a trend for low-mass galaxies to exhibit shallower rotation curve inner slopes than high-mass galaxies, whereas steep inner slopes are found exclusively in high-mass galaxies. This trend may arise from the relationship between the total stellar mass and the mass of the bulge, which are correlated among them. We find a correlation between the inner slope of the rotation curve and the morphological T-type, complementary to the scaling relation between dRvc(0) and {\mu}0 previously reported in the literature. Although we find that the inner slope increases with the Fourier amplitude A2 and decreases with the bar torque Qb, this may arise from the presence of the bulge implicit in both A2 and Qb. As previously noted in the literature, the more compact the mass in the central parts of a galaxy (more concretely, the presence of a bulge), the steeper the inner slopes. We conclude that the baryonic matter dominates the dynamics in the central parts of our sample galaxies.Comment: 11 pages, 11 figures, accepted for publication in MNRA

Comparación y manejo de los diferentes riesgos del agua, en los aspectos social, económico y de la Salud general

El agua en exceso o déficit es perjudicial para los seres vivos y para el desarrollo social y económico de las comunidades. Desastres naturales relacionados con el agua, como las inundaciones y los maremotos son dos ejemplos claros de catástrofes relacionadas con el agua que pueden afectar seriamente el desarrollo integral de ciudades y países, en cualquier esfera productiva. Además de los daños en la actividad económica o en el aspecto social y habitacional, el agua presenta un gran riesgo para las comunidades desde el punto de vista de la salud en general. El agua no potable, la cual desafortunadamente se consume en muchas naciones del mundo, es causante de gran cantidad de enfermedades en pacientes de todas las edades, viéndose más afectada la comunidad infantil de los países en vías de desarrollo. Considerando que en contra del agua y los desastres naturales la fortaleza humana es débil; sí se debe tener claro que hay muchas otras instancias y acciones que las comunidades pueden ejecutar con el objetivo de mitigar daños que tengan relación con el agua, la salud general y el desarrollo de las poblaciones. El manejo e identificación de las posibilidades para mejorarlas anteriores situaciones negativas deben ser producto de la acción y trabajo en conjunto de las administraciones, la academia y los sectores privados, en busca de un beneficio general e integral. ABSTRACTExcess or deficit of water affects living beings, as well as social and economical development inof communities. Natural disasters related to water, such as flooding and tsunamis are two clear examples of risks catastrophes to influencing integral development of cities and countries at any productivity level. Besides the damage to economical, social or constructing aspects, water threatens general health in different communities, from the general health point of view. Non-potable water, which unfortunately is drank in many countries, causes great variety of diseases in patients of all ages, drastically affectingmore drastically infants in underdeveloped countries. Considering that against water and natural disasters, humans men is are not strong enough, ; it is necessary to highlight that in other cases there are many actions communities can undertake to diminish water -related damage, health risks and general development. Identifying and managing different possibilities to improve these  egative situations is must be the result of a joint effort that includes public administration, the academic area and all private institutions in order aware of the need and aiming to achieve a general and integral benefit. El agua en exceso o déficit es perjudicial para los seres vivos y para el desarrollo social y económico de las comunidades. Desastres naturales relacionados con el agua, como las inundaciones y los maremotos son dos ejemplos claros de catástrofes relacionadas con el agua que pueden afectar seriamente el desarrollo integral de ciudades y países, en cualquier esfera productiva. Además de los daños en la actividad económica o en el aspecto social y habitacional, el agua presenta un gran riesgo para las comunidades desde el punto de vista de la salud en general. El agua no potable, la cual desafortunadamente se consume en muchas naciones del mundo, es causante de gran cantidad de enfermedades en pacientes de todas las edades, viéndose más afectada la comunidad infantil de los países en vías de desarrollo. Considerando que en contra del agua y los desastres naturales la fortaleza humana es débil; sí se debe tener claro que hay muchas otras instancias y acciones que las comunidades pueden ejecutar con el objetivo de mitigar daños que tengan relación con el agua, la salud general y el desarrollo de las poblaciones. El manejo e identificación de las posibilidades para mejorarlas anteriores situaciones negativas deben ser producto de la acción y trabajo en conjunto de las administraciones, la academia y los sectores privados, en busca de un beneficio general e integral. ABSTRACTExcess or deficit of water affects living beings, as well as social and economical development inof communities. Natural disasters related to water, such as flooding and tsunamis are two clear examples of risks catastrophes to influencing integral development of cities and countries at any productivity level. Besides the damage to economical, social or constructing aspects, water threatens general health in different communities, from the general health point of view. Non-potable water, which unfortunately is drank in many countries, causes great variety of diseases in patients of all ages, drastically affectingmore drastically infants in underdeveloped countries. Considering that against water and natural disasters, humans men is are not strong enough, ; it is necessary to highlight that in other cases there are many actions communities can undertake to diminish water -related damage, health risks and general development. Identifying and managing different possibilities to improve these  egative situations is must be the result of a joint effort that includes public administration, the academic area and all private institutions in order aware of the need and aiming to achieve a general and integral benefit.

Structural mechanism for regulation of the AAA-ATPases RUVBL1-RUVBL2 in the R2TP co-chaperone revealed by cryo-EM

The human R2TP complex (RUVBL1-RUVBL2-RPAP3-PIH1D1) is an HSP90 co-chaperone required for the maturation of several essential multiprotein complexes, including RNA polymerase II, small nucleolar ribonucleoproteins, and PIKK complexes such as mTORC1 and ATR-ATRIP. RUVBL1-RUVBL2 AAA-ATPases are also primary components of other essential complexes such as INO80 and Tip60 remodelers. Despite recent efforts, the molecular mechanisms regulating RUVBL1-RUVBL2 in these complexes remain elusive. Here, we report cryo-EM structures of R2TP and show how access to the nucleotide-binding site of RUVBL2 is coupled to binding of the client recruitment component of R2TP (PIH1D1) to its DII domain. This interaction induces conformational rearrangements that lead to the destabilization of an N-terminal segment of RUVBL2 that acts as a gatekeeper to nucleotide exchange. This mechanism couples protein-induced motions of the DII domains with accessibility of the nucleotide-binding site in RUVBL1-RUVBL2, and it is likely a general mechanism shared with other RUVBL1-RUVBL2-containing complexes