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

The impact of confounding on the associations of different adiposity measures with the incidence of cardiovascular disease: a cohort study of 296 535 adults of white European descent

Aims: The data regarding the associations of body mass index (BMI) with cardiovascular (CVD) risk, especially for those at the low categories of BMI, are conflicting. The aim of our study was to examine the associations of body composition (assessed by five different measures) with incident CVD outcomes in healthy individuals. Methods and results: A total of 296 535 participants (57.8% women) of white European descent without CVD at baseline from the UK biobank were included. Exposures were five different measures of adiposity. Fatal and non-fatal CVD events were the primary outcome. Low BMI (≤18.5 kg m−2) was associated with higher incidence of CVD and the lowest CVD risk was exhibited at BMI of 22–23 kg m−2 beyond, which the risk of CVD increased. This J-shaped association attenuated substantially in subgroup analyses, when we excluded participants with comorbidities. In contrast, the associations for the remaining adiposity measures were more linear; 1 SD increase in waist circumference was associated with a hazard ratio of 1.16 [95% confidence interval (CI) 1.13–1.19] for women and 1.10 (95% CI 1.08–1.13) for men with similar magnitude of associations for 1 SD increase in waist-to-hip ratio, waist-to-height ratio, and percentage body fat mass. Conclusion: Increasing adiposity has a detrimental association with CVD health in middle-aged men and women. The association of BMI with CVD appears more susceptible to confounding due to pre-existing comorbidities when compared with other adiposity measures. Any public misconception of a potential ‘protective’ effect of fat on CVD risk should be challenged

Ranas del género Pipa (Anura: Pipidae) de la Orinoquia colombiana: nuevos registros y comentarios sobre su taxonomía, distribución e historia natural

Two sympatric species of aquatic frogs (Pipa pipa and Pipa snethlageae) are reported for the first time for the Bita and Orinoco rivers in the moriche palm swamp streams of the floodplain, in the department of Vichada, Colombia. Updated maps are provided with the extensions of the range of these two species, comments on their taxonomy and some aspects of their natural history are described.Se reportan por primera vez dos especies simpátricas de ranas acuáticas (Pipa pipa y Pipa snethlageae) para los ríos Bita y afluentes del río Orinoco en ambientes de morichal de la planicie inundable, departamento del Vichada, Colombia. Se proveen mapas actualizados con la ampliación del área de distribución de estas dos especies, se incluyen comentarios sobre la taxonomía y se describen algunos aspectos sobre su historia natural

Nuevo registro del cecílido Typhlonectes compressicauda (Duméril & Bibron 1841) (Gymnophiona: Typhlonectidae) en la Amazonia colombiana

The first voucher specimen in a reference collection of Typhlonectes compressicauda (Duméril y Bibron 1841) (Gymnophiona: Typhlonectidae), was obtained in the Colombian Amazon, confirming previous observations in the region. Additional information obtained provide additional knowledge about their life history and in particular physical and chemical habitat features.Se registra el primer ejemplar en colección de referencia de Typhlonectes compressicauda (Duméril y Bibron 1841) (Gymnophiona: Typhlonectidae), proveniente de la Amazonia colombiana, corroborando así observaciones previas en la región. Los datos obtenidos incorporan información adicional sobre la historia de vida, especialmente aspectos relacionados con características físicas y químicas del hábitat

Ranas del género Pipa (Anura: Pipidae) de la Orinoquia colombiana: nuevos registros y comentarios sobre su taxonomía, distribución e historia natural

Se reportan por primera vez dos especies simpátricas de ranas acuáticas (Pipa pipa y Pipa snethlageae) para los ríos Bita y afluentes del río Orinoco en ambientes de morichal de la planicie inundable, departamento del Vichada, Colombia. Se proveen mapas actualizados con la ampliación del área de distribución de estas dos especies, se incluyen comentarios sobre la taxonomía y se describen algunos aspectos sobre su historia natural

New record of the caecilian <em>Typhlonectes compressicauda<em> (Duméril & Bibron 1841) (Gymnophiona: Typhlonectidae) from the Colombian Amazon Basin

The first voucher specimen in a reference collection of Typhlonectes compressicauda (Duméril y Bibron 1841) (Gymnophiona: Typhlonectidae), was obtained in the Colombian Amazon, confirming previous observations in the region. Additional information obtained provide additional knowledge about their life history and in particular physical and chemical habitat features

Associations between diabetes and both cardiovascular disease and all-cause mortality are modified by grip strength: evidence from UK Biobank, a prospective population-based cohort study

OBJECTIVE Grip strength and diabetes are predictors of mortality and cardiovascular disease (CVD), but whether these risk factors interact to predispose to adverse health outcomes is unknown. This study determined the interactions between diabetes and grip strength and their association with health outcomes. RESEARCH DESIGN AND METHODS We undertook a prospective, general population cohort study by using UK Biobank. Cox proportional hazards models were used to explore the associations between both grip strength and diabetes and the outcomes of all-cause mortality and CVD incidence/mortality as well as to test for interactions between diabetes and grip strength. RESULTS 347,130 UK Biobank participants with full data available (mean age 55.9 years, BMI 27.2 kg/m2, 54.2% women) were included in the analysis, of which 13,373 (4.0%) had diabetes. Over a median follow-up of 4.9 years (range 3.3–7.8 years), 6,209 died (594 as a result of CVD), and 4,301 developed CVD. Participants with diabetes were at higher risk of all-cause and CVD mortality and CVD incidence. Significant interactions (P &lt; 0.05) existed whereby the risk of CVD mortality was higher in participants with diabetes with low (hazard ratio [HR] 4.05 [95% CI 2.72, 5.80]) versus high (HR 1.46 [0.87, 2.46]) grip strength. Similar results were observed for all-cause mortality and CVD incidence. CONCLUSIONS Risk of adverse health outcomes among people with diabetes is lower in those with high grip strength. Low grip strength may be useful to identify a higher-risk subgroup of patients with diabetes. Intervention studies are required to determine whether resistance exercise can reduce risk

Optimization of laser-firing processes for silicon-heterojunction solar-cell back contacts

One of the key steps to achieve high efficiencies in amorphous/crystalline silicon photovoltaic structures is to design low-ohmic-resistance backcontacts with good passivation in the rear part of the cell. A well known approach to achieve this goal is to use laser-fired contact (LFC) processes in which a metal layer is fired through the dielectric to define good contacts with the semiconductor. However, and despite the fact that this approach has demonstrated to be extremely successful, there is still enough room for process improvement with an appropriate optimization. In this paper, a study focused on the optimal adjustment of the irradiation parameters to produce laser-fired contacts in a-Si:H/c-Si heterojunctionsolarcells is presented. We used samples consisting of crystalline-silicon (c-Si) wafers together with a passivation layer of intrinsic hydrogenated amorphous silicon (a-Si:H(i)) deposited by plasma-enhanced chemical deposition (PECVD). Then, an aluminum layer was evaporated on both sides, the thickness of this layer varied from 0.2 to 1 μm in order to identify the optimal amount of Al required to create an appropriate contact. A q-switched Nd:YVO4laser source, λ = 532 nm, was used to locally fire the aluminum through the thin a-Si:H(i)-layers to form the LFC. The effects of laser fluences were analyzed using a comprehensive morphological and electrical characterization

Identification of vaginal microbiome associated with IVF pregnancy

The factors that cause a preterm birth (PTB) are not completely understood up to date. Moreover, PTB is more common in pregnancies achieved by in-vitro fertilization (IVF) than in spontaneous pregnancies. Our aim was to compare the composition of vaginal microbiome at 12 weeks of gestation between women who conceived naturally or through IVF in order to study whether IVF PTB-risk could be related to vaginal microbiome composition. We performed an observational, prospective and multicentre study among two public hospitals and a fertility private clinic in Spain. Vaginal swabs from 64 pregnant women at 12 weeks of gestation were collected to analyse the microbiome composition by sequencing the V3–V4 region of the 16S rRNA. Our results showed that the vaginal microbiome signature at 12 weeks of pregnancy was different from women who conceived naturally or through IVF. The beta diversity and the genus composition were different between both cohorts. Gardnerella, Neisseria, Prevotella, and Staphylococcus genus were enriched genus in the vaginal microbiome from the IVF group, allowing us to create a balance model to predict both cohorts. Moreover, at species level the L. iners abundance was higher and L. gasseri was lower in the IVF group. As a conclusion, our findings were consistent with a proposed framework in which IVF pregnancy are related to risk for preterm birth (PTB) suggesting vaginal microbiome could be the reason to the relation between IVF pregnancy and risk for PTB

Associations of grip strength with cardiovascular, respiratory, and cancer outcomes and all cause mortality: prospective cohort study of half a million UK Biobank participants

Objective: To investigate the association of grip strength with disease specific incidence and mortality and whether grip strength enhances the prediction ability of an established office based risk score. Design: Prospective population based study. Setting: UK Biobank. Participants: 502 293 participants (54% women) aged 40-69 years. Main outcome measures: All cause mortality as well as incidence of and mortality from cardiovascular disease, respiratory disease, chronic obstructive pulmonary disease, and cancer (all cancer, colorectal, lung, breast, and prostate). Results: Of the participants included in analyses, 13 322 (2.7%) died over a mean of 7.1 (range 5.3-9.9) years’ follow-up. In women and men, respectively, hazard ratios per 5 kg lower grip strength were higher (all at P&lt;0.05) for all cause mortality (1.20, 95% confidence interval 1.17 to 1.23, and 1.16, 1.15 to 1.17) and cause specific mortality from cardiovascular disease (1.19, 1.13 to 1.25, and 1.22, 1.18 to 1.26), all respiratory disease (1.31, 1.22 to 1.40, and 1.24, 1.20 to 1.28), chronic obstructive pulmonary disease (1.24, 1.05 to 1.47, and 1.19, 1.09 to 1.30), all cancer (1.17, 1.13 to 1.21, 1.10, 1.07 to 1.13), colorectal cancer (1.17, 1.04 to 1.32, and 1.18, 1.09 to 1.27), lung cancer (1.17, 1.07 to 1.27, and 1.08, 1.03 to 1.13), and breast cancer (1.24, 1.10 to 1.39) but not prostate cancer (1.05, 0.96 to 1.15). Several of these relations had higher hazard ratios in the younger age group. Muscle weakness (defined as grip strength &lt;26 kg for men and &lt;16 kg for women) was associated with a higher hazard for all health outcomes, except colon cancer in women and prostate cancer and lung cancer in both men and women. The addition of handgrip strength improved the prediction ability, based on C index change, of an office based risk score (age, sex, diabetes diagnosed, body mass index, systolic blood pressure, and smoking) for all cause (0.013) and cardiovascular mortality (0.012) and incidence of cardiovascular disease (0.009). Conclusion: Higher grip strength was associated with a range of health outcomes and improved prediction of an office based risk score. Further work on the use of grip strength in risk scores or risk screening is needed to establish its potential clinical utility