151 research outputs found
Factors controlling phytoplankton in tropical high-mountain drinking-water reservoirs
Hydraulic dynamics is one of the primary factors determining the structural and temporal changes in phytoplankton communities in reservoirs. There is little information on the factors that explain the temporal changes in biotic communities in the high-mountain reservoirs that provide water to the city of Bogotá (Colombia). Our objective was to identify the environmental factors controlling the biomass and composition of algal communities in four tropical high-mountain reservoirs. We hypothesised that hydraulic dynamics is the major determining factor in temporal changes in phytoplankton communities in tropical mountain reservoirs regardless of the nutrient concentration in the system. We studied the temporal changes in phytoplankton over five years in four reservoirs that exhibit different nutrient concentrations and hydraulic management regimes. The phytoplankton in all of the reservoirs were characterised by the dominance of Dinophyceae. Canonical correspondence analyses and Pearson's correlations showed that the water renewal rate primarily explains the phytoplankton composition, followed by total nitrogen, total phosphorous and silicates. The effect of the water renewal rate was different depending on the particular conditions in each system; thus, in reservoirs with greater hydraulic dynamics, the water renewal rate explained the selection of secondary species and dominant species adapted to a broad range of environmental conditions. In the reservoir with a higher physical stability, eventual changes in the water renewal rate shifted the dominant species, reduced diversity and altered phytoplankton succession. In the reservoir with the largest volume and lowest nutrient concentration, phytoplankton species were selected primarily based on chemical and physical variables related to climatic seasonality. Our results suggest that the model for hydraulic management of the reservoirs plays an important role: in highly dynamic reservoirs, there is a direct causal relationship between phytoplankton and physical variables such as stability and water renewal rate; in less dynamic environments, phytoplankton species growth responds primarily to water chemistry.La dinámica hidráulica es uno de los principales factores que determinan la estructura y los cambios temporales de las comunidades fitoplanctónicas en embalses. Información de los factores que explican los cambios temporales de las comunidades biológicas en los embalses de alta montaña que proveen de agua la ciudad de Bogotá es escasa. El objetivo de este trabajo fue identificar los factores ambientales que controlan la biomasa y la composición de las comunidades algales en cuatro embalses tropicales de alta montaña. La hipótesis de trabajo fue que la dinámica hidráulica es el factor que principalmente determina los cambios temporales en la comunidad fitoplanctónica, con respecto a la concentración de nutrientes del sistema. Durante cinco años se estudiaron los cambios temporales del fitoplancton en cuatro embalses que se caracterizan por presentar diferentes concentraciones de nutrientes y diferente manejo hidráulico. El fitoplancton de todos los embalses se caracterizó por la dominancia de Dinophyceae. Análisis de Correspondencia Canónica y correlaciones de Pearson mostraron que la tasa de renovación hídrica explicó primariamente el fitoplancton seguida por el nitrógeno total, el fósforo total y los silicatos. El efecto de la tasa de renovación hídrica sobre el fitoplancton fue diferente dependiendo de las condiciones particulares de cada sistema; así, en embalses con una alta dinámica hidráulica, la tasa de renovación explicó las especies secundarias y seleccionó especies dominantes adaptadas a un amplio rango de condiciones ambientales. En el embalse con alta estabilidad física, cambios eventuales en la tasa de renovación cambiaron las especies dominantes, redujeron la diversidad y modificaron la sucesión del fitoplancton. En el embalse de mayor volumen y más baja concentración de nutrientes, el fitoplancton es seleccionado principalmente por otras variables físicas y químicas relacionadas con la estacionalidad climática. Los resultados sugieren que el modelo de manejo hidráulico de los embalses juega un papel importante en embalses más dinámicos, al determinar una relación causal directa entre el fitoplancton y variables físicas como la estabilidad y la tasa de renovación hídrica, mientras en embalses menos dinámicos, el crecimiento de las especies respondió principalment a la química del agua
Morphological description of the southeastern Cyprus outer shelf and slope regions (eastern Mediterranean)
We present here the first results of the analysis and interpretation of the swath bathymetry and side scan sonar data collected along the southeastern outer shelf and upper slope regions of the Cyprus insular margin (offshore Cape Greco). The resultant bathymetric model and the derivatives (e.g.: slope, aspect, benthic position index) are presented and analyzed in order to describe the morphology of the seabed and the main geomorphological features through quantitative indicators including morphometric indexes and statistical descriptors. The presence of deep sea coral communities (Dendrophylia ramea) in a particular location of the surveyed area is also discussed and tentatively related to the landscape morphology where the colonies are settle
Ocean Circulation over North Atlantic underwater features in the path of the Mediterranean Outflow Water: Ormonde and Formigas seamounts, and the Gazul mud volcano
Seamounts constitute an obstacle to the ocean circulation, modifying it. As a result, a
variety of hydrodynamical processes and phenomena may take place over seamounts,
among others, flow intensification, current deflection, upwelling, Taylor caps, and
internal waves. These oceanographic effects may turn seamounts into very productive
ecosystems with high species diversity, and in some cases, are densely populated by
benthic organisms, such corals, gorgonians, and sponges. In this study, we describe the
oceanographic conditions over seamounts and other underwater features in the path of
the Mediterranean Outflow Water (MOW), where populations of benthic suspensions
feeders have been observed. Using CTD, LADPC and biochemical measurements
carried out in the Ormonde and Formigas seamounts and the Gazul mud volcano
(Northeast Atlantic), we show that Taylor caps were not observed in any of the sampled
features. However, we point out that the relatively high values of the Brunt–Väisälä
frequency in the MOW halocline, in conjunction with the slope of the seamount flanks,
set up conditions for the breakout of internal waves and amplification of the currents.
This may enhance the vertical mixing, resuspending the organic material deposited
on the seafloor and, therefore, increasing the food availability for the communities
dominated by benthic suspension feeders. Thus, we hypothesize that internal waves
could be improving the conditions for benthic suspension feeders to grow on the slope
of seamounts.En prens
The Effect of a Physical Activity Program on the Total Number of Primary Care Visits in Inactive Patients: A 15-Month Randomized Controlled Trial
Abstract
Background: Effective promotion of exercise could result in substantial savings in healthcare cost expenses in terms of
direct medical costs, such as the number of medical appointments. However, this is hampered by our limited knowledge of
how to achieve sustained increases in physical activity.
Objectives: To assess the effectiveness of a Primary Health Care (PHC) based physical activity program in reducing the total
number of visits to the healthcare center among inactive patients, over a 15-month period.
Research Design: Randomized controlled trial.
Subjects: Three hundred and sixty-two (n = 362) inactive patients suffering from at least one chronic condition were
included. One hundred and eighty-three patients (n = 183; mean (SD); 68.3 (8.8) years; 118 women) were randomly allocated
to the physical activity program (IG). One hundred and seventy-nine patients (n = 179; 67.2 (9.1) years; 106 women) were
allocated to the control group (CG). The IG went through a three-month standardized physical activity program led by
physical activity specialists and linked to community resources.
Measures: The total number of medical appointments to the PHC, during twelve months before and after the program, was
registered. Self-reported health status (SF-12 version 2) was assessed at baseline (month 0), at the end of the intervention
(month 3), and at 12 months follow-up after the end of the intervention (month 15).
Results: The IG had a significantly reduced number of visits during the 12 months after the intervention: 14.8 (8.5). The CG
remained about the same: 18.2 (11.1) (P = .002).
Conclusions: Our findings indicate that a 3-month physical activity program linked to community resources is a shortduration,
effective and sustainable intervention in inactive patients to decrease rates of PHC visits.
Trial Registration: ClinicalTrials.gov NCT0071483
Dimensionality-driven metal-insulator transition in spin-orbit-coupled IrO_2
A metal-insulator transition is observed in spin-orbit-coupled IrO_2 thin films upon reduction of the film thickness. In the epitaxially grown samples, the critical thickness (t similar to 1.5-2.2 nm) is found to depend on growth orientation (001), (100) or (110). Interestingly from the applied point of view, the insulating behavior is found even in polycrystalline ultrathin films. By analyzing the experimental electrical response with various theoretical models, we find good fits to the Efros-Shklovskii-VRH and the Arrhenius-type behaviors, which suggests an important role of electron correlations in determining the electrical properties of IrO_2. Our magnetic measurements also point to a significant role of magnetic order. Altogether, our results would point to a mixed Slater- and Mott-type of insulator
Immune and spermatogenesis-related loci are involved in the development of extreme patterns of male infertility
We conducted a genome-wide association study in a large population of infertile men due to unexplained spermatogenic failure (SPGF). More than seven million genetic variants were analysed in 1,274 SPGF cases and 1,951 unaffected controls from two independent European cohorts. Two genomic regions were associated with the most severe histological pattern of SPGF, defined by Sertoli cell-only (SCO) phenotype, namely the MHC class II gene HLA-DRB1 (rs1136759, P = 1.32E-08, OR = 1.80) and an upstream locus of VRK1 (rs115054029, P = 4.24E-08, OR = 3.14), which encodes a protein kinase involved in the regulation of spermatogenesis. The SCO-associated rs1136759 allele (G) determines a serine in the position 13 of the HLA-DR beta 1 molecule located in the antigen-binding pocket. Overall, our data support the notion of unexplained SPGF as a complex trait influenced by common variation in the genome, with the SCO phenotype likely representing an immune-mediated condition. A GWAS in a large case-control cohort of European ancestry identifies two genomic regions, the MHC class II gene HLA-DRB1 and an upstream locus of VRK1, that are associated with the most severe phenotype of spermatogenic failure
Cruise Summary Report - MEDWAVES survey. MEDiterranean out flow WAter and Vulnerable EcosystemS (MEDWAVES)
The MEDWAVES (MEDiterranean out flow WAter and Vulnerable EcosystemS) cruise targeted areas under the potential influence of the MOW within the Mediterranean and Atlantic realms. These include seamounts where Cold-water corals (CWCs) have been reported but that are still poorly known, and which may act as essential “stepping stones” connecting fauna of seamounts in the Mediterranean with those of the continental shelf of Portugal, the Azores and the Mid-Atlantic Ridge. During MEDWAVES sampling has been conducted in two of the case studies of ATLAS: Case study 7 (Gulf of Cádiz-Strait of Gibraltar-Alboran Sea) and Case study 8 (Azores).
The initially targeted areas in the Atlantic were: the Gazul Mud volcano, in the Gulf of Cádiz (GoC) area, included in the case study 7, and the Atlantic seamounts Ormonde (Portuguese shelf) and Formigas (by Azores), both part of the case study 8. In the Mediterranean the targeted areas were The Guadiaro submarine canyon and the Seco de los Olivos (also known as Chella Bank) seamount. Unfortunately it was not possible to sample in Guadiaro due to time constraints originated by adverse meteorological conditions which obligate us to reduce the time at sea focusing only in 4 of the 5 initially planned areas.
MEDWAVES was structured in two legs; the first leg took place from the 21st September (departure from Cádiz harbour in Spain) to the 13th October 2016 (arrival in Ponta Delgada, São Miguel, Azores, Portugal took place the 8th of October due to the meteorological conditions that obligated to conclude the first leg earlier as planned). during the Leg 1 sampling was carried out in Gazul, Ormonde and Formigas. The second leg started the 14th October (departure from Ponta Delgada) and finished the 26th October (arrival in Málaga harbour, Spain). MEDWAVES had a total of 30 effective sampling days, being 6 days not operative due to the adverse meteorological conditions experienced during the first leg which forced us to stay in Ponta Delgada from the 08th to the 13th October.
During MEDWAVES the daily routine followed a similar scheme, depending of course on the weather and sea conditions. The main activity during the day, starting early in the morning (around 08:00 AM, once the night activities were finished), was the ROV deployment. Generally a single ROV dive of around 8 hours was performed, however in several occasions two dives were carried out in the same day (see General station list, Appendix II). After the ROV (and sometimes between two dives) the Box Corer and/or Van Veen Grab and/or Multicore was deployed. After these activities, during the night CTD-Rosette deployments and MB was conducted. Accordingly to this schema the scientific personnel worked in the day or in the night watch.
A total of 215 sampling stations have been covered in MEDWAVES, using the following sampling gears: Multibeam echosounder, CTD-Rosette, LADCP, Box Corer, Van Veen Grab, Multicorer and a Remotely Operated Vehicle (ROV). Table 1 sumamrised the number of sampling stations conducted with each gear in each sampling zone. Additionally MB surveys have been conducted during the transits between area
Immune and spermatogenesis-related loci are involved in the development of extreme patterns of male infertility.
We conducted a genome-wide association study in a large population of infertile men due to unexplained spermatogenic failure (SPGF). More than seven million genetic variants were analysed in 1,274 SPGF cases and 1,951 unaffected controls from two independent European cohorts. Two genomic regions were associated with the most severe histological pattern of SPGF, defined by Sertoli cell-only (SCO) phenotype, namely the MHC class II gene HLA-DRB1 (rs1136759, P = 1.32E-08, OR = 1.80) and an upstream locus of VRK1 (rs115054029, P = 4.24E-08, OR = 3.14), which encodes a protein kinase involved in the regulation of spermatogenesis. The SCO-associated rs1136759 allele (G) determines a serine in the position 13 of the HLA-DRβ1 molecule located in the antigen-binding pocket. Overall, our data support the notion of unexplained SPGF as a complex trait influenced by common variation in the genome, with the SCO phenotype likely representing an immune-mediated condition.We thank the National DNA Bank Carlos III (University of Salamanca, Spain) for supplying part of the control DNA samples from Spain and all the participants for their essential collaboration. This work was supported by the Spanish Ministry of Science through the Spanish National Plan for Scientific and Technical Research and Innovation (refs. SAF2016-78722-R and PID2020-120157RB-I00), the Andalusian Plan for Research and Innovation (PAIDI 2020) (ref. PY20_00212), and the R+D+i Projects of the FEDER Operational Programme 2020 (ref. B-CTS-584-UGR20). F.D.C. was supported by the “Ramón y Cajal” programme (ref. RYC-2014-16458), and L.B.C. was supported by the Spanish Ministry of Economy and Competitiveness through the “Juan de la Cierva Incorporación” programme (ref. IJC2018-038026-I, funded by MCIN/AEI /10.13039/501100011033), all of them including FEDER funds. A.G.J. was funded by MCIN/AEI /10.13039/501100011033 and FSE “El FSE invierte en tu futuro” (ref. FPU20/02926). IPATIMUP integrates the i3S Research Unit, which is partially supported by the Portuguese Foundation for Science and Technology (FCT), financed by the European Social Funds (COMPETE-FEDER) and National Funds (projects PEstC/SAU/LA0003/2013 and POCI-01-0145-FEDER-007274). A.M.L. is funded by the Portuguese Government through FCT (IF/01262/2014). P.I.M. is supported by the FCT post-doctoral fellowship (SFRH/BPD/120777/2016), financed from the Portuguese State Budget of the Ministry for Science, Technology and High Education and from the European Social Fund, available through the Programa Operacional do Capital Humano. ToxOmics—Centre for Toxicogenomics and Human Health, Genetics, Oncology and Human Toxicology, Nova Medical School, Lisbon, is also partially supported by FCT (Projects: UID/BIM/00009/2013 and UIDB/UIDP/00009/2020). SLarriba received support from “Instituto de Salud Carlos III” (grant DTS18/00101], co-funded by FEDER funds/European Regional Development Fund (ERDF)—a way to build Europe), and from “Generalitat de Catalunya” (grant 2017SGR191). SLarriba is sponsored by the “Researchers Consolidation Programme” from the SNS-Departament de Salut Generalitat de Catalunya (Exp. CES09/020). The German cohort was recruited within the Male Reproductive Genomics (MERGE) study and supported by the German Research Foundation Clinical Research Unit ‘Male Germ Cells’ (DFG CRU326, grants to F.T. and J.G.). This article is related to the Ph.D. Doctoral Thesis of Miriam Cerván-Martín (grant ref. BES-2017-081222 funded by MCIN/AEI/10.13039/501100011033 and FSE “El FSE invierte en tu futuro”)
Symbol Digit Modalities Test: Normative data for Spanish-speaking pediatric population
OBJECTIVE: To generate normative data for the Symbol Digit Modalities Test (SDMT) in Spanish-speaking pediatric populations. METHOD: The sample consisted of 4,373 healthy children from nine countries in Latin America (Chile, Cuba, Ecuador, Guatemala, Honduras, Mexico, Paraguay, Peru, and Puerto Rico) and Spain. Each participant was administered the SDMT as part of a larger neuropsychological battery. SDMT scores were normed using multiple linear regressions and standard deviations of residual values. Age, age2, sex, and mean level of parental education (MLPE) were included as predictors in the analyses. RESULTS: The final multiple linear regression models showed main effects for age in all countries, such that score increased linearly as a function of age. In addition, age2 had a significant effect in all countries, except in Honduras and Puerto Rico. Models indicated that children whose parent(s) had a MLPE >12 years of education obtained higher score compared to children whose parent(s) had a MLPE ≤12 years for Chile, Guatemala, Mexico, and Spain. Sex affected SDMT score for Paraguay and Spain. CONCLUSIONS: This is the largest Spanish-speaking pediatric normative study in the world, and it will allow neuropsychologists from these countries to have a more accurate interpretation of the SDMT with pediatric populations
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