Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 63
Filtrar
Más filtros

Base de datos
País/Región como asunto
Tipo del documento
Intervalo de año de publicación
1.
Agric Water Manag ; 255: 107036, 2021 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-34483463

RESUMEN

Laser land levelling is expanding rapidly in the rice-wheat (RW) and maize-wheat (MW) systems of the Indo-Gangetic Plains of India and Pakistan. Current practice is to level to zero (0%) gradient, whereas a small gradient (e.g. 0.1%) is typically used in developed countries. Therefore, experiments were conducted in farmers' plots (~15 m x 40 m) in the Eastern Gangetic Plains to evaluate laser levelling with a 0.1% gradient in comparison with 0% and farmer levelling practice (FL). The study was conducted over two years in RW and MW systems. In the MW system, raised beds in plots lasered with 0% and 0.1% gradients were also evaluated. Laser levelling with 0% gradient significantly reduced irrigation amount and/or increased irrigation water productivity (WPi) in all crops/systems grown on the flat compared to FL except for wheat in the MW system. While there was a consistent trend for higher yield with a 0% gradient compared with FL, the differences were not significant in any crop/system. For the RW system, the results suggest no to marginal benefits in irrigation amount and WPi from levelling with a 0.1% gradient in comparison with 0% gradient. In that system, by far the bigger gains were from changing from FL to laser levelling with 0% gradient. This resulted in substantial reductions in irrigation amount, which greatly increased WPi in both crops (by ~40%), while yield was not affected. Rice grown with FL was not profitable, but lasering with 0% gradient significantly increased gross margin for rice, wheat and the total RW system. As for the RW system, levelling to 0% with a flat configuration significantly increased WPi of both crops in the MW system compared to FL, but by a lesser proportion. Raised beds significantly increased yield of maize by 8% (0.5 t ha-1), reduced irrigation amount by 20% (40 mm) and increased WPi by 34% (1.0 kg m-3) in comparison with the laser levelled flat plots. Gross margin of the MW system on beds was 17-20% higher than FL, and gross margin with beds on a 0.1% gradient was significantly higher than either gradient on the flat. The results suggest that the gains from levelling with a 0.1% gradient compared to 0% are marginal; however, this may change if the goal of consolidation of small farmer plots into larger fields becomes a reality provided there is a proportionate increase in irrigation flow rates, and ability to drain.

2.
J Adv Model Earth Syst ; 11(7): 2130-2162, 2019 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33101595

RESUMEN

Peatlands are poorly represented in global Earth system modeling frameworks. Here we add a peatland-specific land surface hydrology module (PEAT-CLSM) to the Catchment Land Surface Model (CLSM) of the NASA Goddard Earth Observing System (GEOS) framework. The amended TOPMODEL approach of the original CLSM that uses topography characteristics to model catchment processes is discarded, and a peatland-specific model concept is realized in its place. To facilitate its utilization in operational GEOS efforts, PEAT-CLSM uses the basic structure of CLSM and the same global input data. Parameters used in PEAT-CLSM are based on literature data. A suite of CLSM and PEAT-CLSM simulations for peatland areas between 40°N and 75°N is presented and evaluated against a newly compiled data set of groundwater table depth and eddy covariance observations of latent and sensible heat fluxes in natural and seminatural peatlands. CLSM's simulated groundwater tables are too deep and variable, whereas PEAT-CLSM simulates a mean groundwater table depth of -0.20 m (snow-free unfrozen period) with moderate temporal fluctuations (standard deviation of 0.10 m), in significantly better agreement with in situ observations. Relative to an operational CLSM version that simply includes peat as a soil class, the temporal correlation coefficient is increased on average by 0.16 and reaches 0.64 for bogs and 0.66 for fens when driven with global atmospheric forcing data. In PEAT-CLSM, runoff is increased on average by 38% and evapotranspiration is reduced by 19%. The evapotranspiration reduction constitutes a significant improvement relative to eddy covariance measurements.

3.
Astron Astrophys ; 6022017 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-29151605

RESUMEN

AIMS: Extragalactic observations of water emission can provide valuable insights into the excitation of the interstellar medium. In particular they allow us to investigate the excitation mechanisms in obscured nuclei, i.e. whether an active galactic nucleus or a starburst dominate. METHODS: We use sub-arcsecond resolution observations to tackle the nature of the water emission in Arp 220. ALMA Band 5 science verification observations of the 183 GHz H2O 313-220 line, in conjunction with new ALMA Band 7 H2O 515-422 data at 325 GHz, and supplementary 22 GHz H2O 616 - 523 VLA observations, are used to better constrain the parameter space in the excitation modelling of the water lines. RESULTS: We detect 183 GHz H2O and 325 GHz water emission towards the two compact nuclei at the center of Arp 220, being brighter in Arp 220 West. The emission at these two frequencies is compared to previous single-dish data and does not show evidence of variability. The 183 and 325 GHz lines show similar spectra and kinematics, but the 22 GHz profile is significantly different in both nuclei due to a blend with an NH3 absorption line. CONCLUSIONS: Our findings suggest that the most likely scenario to cause the observed water emission in Arp 220 is a large number of independent masers originating from numerous star-forming regions.

4.
Astron Astrophys ; 6052017 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-29142327

RESUMEN

CONTEXT: Recent observations at subarcsecond resolution, now possible also at submillimeter wavelengths, have shown intricate circumstellar structures around asymptotic giant branch (AGB) stars, mostly attributed to binary interaction. The results presented here are part of a larger project aimed at investigating the effects of a binary companion on the morphology of circumstellar envelopes (CSEs) of AGB stars. AIMS: AGB stars are characterized by intense stellar winds that build CSEs around the stars. Here, the CO(J = 3→2) emission from the CSE of the binary S-type AGB star W Aql has been observed at subarcsecond resolution using ALMA. The aim of this paper is to investigate the wind properties of the AGB star and to analyse how the known companion has shaped the CSE. METHODS: The average mass-loss rate during the creation of the detected CSE is estimated through modelling, using the ALMA brightness distribution and previously published single-dish measurements as observational constraints. The ALMA observations are presented and compared to the results from a 3D smoothed particle hydrodynamics (SPH) binary interaction model with the same properties as the W Aql system and with two different orbital eccentricities. Three-dimensional radiative transfer modelling is performed and the response of the interferometer is modelled and discussed. RESULTS: The estimated average mass-loss rate of W Aql is M = 3.0×10-6 M⊙ yr-1 and agrees with previous results based on single-dish CO line emission observations. The size of the emitting region is consistent with photodissociation models. The inner 10″ of the CSE is asymmetric with arc-like structures at separations of 2-3″ scattered across the denser sections. Further out, weaker spiral structures at greater separations are found, but this is at the limit of the sensitivity and field of view of the ALMA observations. CONCLUSIONS: The CO(J = 3→2) emission is dominated by a smooth component overlayed with two weak arc patterns with different separations. The larger pattern is predicted by the binary interaction model with separations of ~10″ and therefore likely due to the known companion. It is consistent with a binary orbit with low eccentricity. The smaller separation pattern is asymmetric and coincides with the dust distribution, but the separation timescale (200 yrs) is not consistent with any known process of the system. The separation of the known companions of the system is large enough to not have a very strong effect on the circumstellar morphology. The density contrast across the envelope of a binary with an even larger separation will not be easily detectable, even with ALMA, unless the orbit is strongly asymmetric or the AGB star has a much larger mass-loss rate.

5.
Oncogenesis ; 6(6): e346, 2017 Jun 12.
Artículo en Inglés | MEDLINE | ID: mdl-28604763

RESUMEN

Breast tumours progress from hyperplasia to ductal carcinoma in situ (DCIS) and invasive breast carcinoma (IBC). PRH/HHEX (proline-rich homeodomain/haematopoietically expressed homeobox) is a transcription factor that displays both tumour suppressor and oncogenic activity in different disease contexts; however, the role of PRH in breast cancer is poorly understood. Here we show that nuclear localization of the PRH protein is decreased in DCIS and IBC compared with normal breast. Our previous work has shown that PRH phosphorylation by protein kinase CK2 prevents PRH from binding to DNA and regulating the transcription of multiple genes encoding growth factors and growth factor receptors. Here we show that transcriptionally inactive phosphorylated PRH is elevated in DCIS and IBC compared with normal breast. To determine the consequences of PRH loss of function in breast cancer cells, we generated inducible PRH depletion in MCF-7 cells. We show that PRH depletion results in increased MCF-7 cell proliferation in part at least due to increased vascular endothelial growth factor signalling. Moreover, we demonstrate that PRH depletion increases the formation of breast cancer cells with cancer stem cell-like properties. Finally, and in keeping with these findings, we show that PRH overexpression inhibits the growth of mammary tumours in mice. Collectively, these data indicate that PRH plays a tumour suppressive role in the breast and they provide an explanation for the finding that low PRH mRNA levels are associated with a poor prognosis in breast cancer.

6.
Oncogenesis ; 6(1): e293, 2017 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-28134934

RESUMEN

PRH/HHEX (proline-rich homeodomain protein/haematopoietically expressed homeobox protein) is a transcription factor that controls cell proliferation, cell differentiation and cell migration. Our previous work has shown that in haematopoietic cells, Protein Kinase CK2-dependent phosphorylation of PRH results in the inhibition of PRH DNA-binding activity, increased cleavage of PRH by the proteasome and the misregulation of PRH target genes. Here we show that PRH and hyper-phosphorylated PRH are present in normal prostate epithelial cells, and that hyper-phosphorylated PRH levels are elevated in benign prostatic hyperplasia, prostatic adenocarcinoma, and prostate cancer cell lines. A reduction in PRH protein levels increases the motility of normal prostate epithelial cells and conversely, PRH over-expression inhibits prostate cancer cell migration and blocks the ability of these cells to invade an extracellular matrix. We show that CK2 over-expression blocks the repression of prostate cancer cell migration and invasion by PRH. In addition, we show that PRH knockdown in normal immortalised prostate cells results in an increase in the population of cells capable of colony formation in Matrigel, as well as increased cell invasion and decreased E-cadherin expression. Inhibition of CK2 reduces PRH phosphorylation and reduces prostate cell proliferation but the effects of CK2 inhibition on cell proliferation are abrogated in PRH knockdown cells. These data suggest that the increased phosphorylation of PRH in prostate cancer cells increases both cell proliferation and tumour cell migration/invasion.

7.
Field Crops Res ; 197: 83-96, 2016 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-27698532

RESUMEN

Machinery for sowing wheat directly into rice residues has become more common in the rice-wheat systems of the north-west Indo-Gangetic Plains of South Asia, with increasing numbers of farmers now potentially able to access the benefits of residue retention. However, surface residue retention affects soil water and temperature dynamics, thus the optimum sowing date and irrigation management for a mulched crop may vary from those of a traditional non-mulched crop. Furthermore, the effects of sowing date and irrigation management are likely to vary with soil type and seasonal conditions. Therefore, a simulation study was conducted using the APSIM model and 40 years of weather data to evaluate the effects of mulch, sowing date and irrigation management and their interactions on wheat grain yield, irrigation requirement (I) and water productivity with respect to irrigation (WPI) and evapotranspiration (WPET). The results suggest that the optimum wheat sowing date in central Punjab depends on both soil type and the presence or absence of mulch. On the sandy loam, with irrigation scheduled at 50% soil water deficit (SWD), the optimum sowing date was late October to early November for maximising yield, WPI and WPET. On the clay loam, the optimum date was about one week later. The effect of mulch on yield varied with seasonal conditions and sowing date. With irrigation at 50% SWD, mulching of wheat sown at the optimum time increased average yield by up to 0.5 t ha-1. The beneficial effect of mulch on yield increased to averages of 1.2-1.3 t ha-1 as sowing was advanced to 15 October. With irrigation at 50% SWD and 7 November sowing, mulch reduced the number of irrigations by one in almost 50% of years, a reduction of about 50 mm on the sandy loam and 60 mm on the clay loam. The reduction in irrigation amount was mainly due to reduced soil evaporation. Mulch reduced irrigation requirement by more as sowing was delayed, more so on the sandy loam than the clay loam soil. There was little effect of mulch on irrigation requirement for late October sowings. There were large trade-offs between irrigation input, yield, WPET and WPI on the sandy loam with regard to the optimum irrigation schedule. Maximum yield occurred with very frequent irrigation (10-20% SWD) which also had the greatest irrigation input, while WPI was highest with least frequent irrigation (70% SWD), and WPET was highest with irrigation at 40-50% SWD. This was the case with and without mulch. On the clay loam, the trade-offs were not so pronounced, as maximum yield was reached with irrigation at 50% SWD, with and without mulch. However, both WPET and WPI were maximum and irrigation input least at the lowest irrigation frequency (70% SWD). On both soils, maximum yield, WPET and WPI were higher with mulch, while irrigation input was slightly lower, but mulch had very little effect on the irrigation thresholds at which each parameter was maximised.

8.
Virchows Arch ; 468(5): 607-17, 2016 May.
Artículo en Inglés | MEDLINE | ID: mdl-26861919

RESUMEN

The prognostic value of phosphatase and tensin homolog (PTEN) loss in prostate cancer has primarily been evaluated by either fluorescence in situ hybridization (FISH) or immunohistochemistry (IHC). Previously, we found that PTEN loss by IHC was associated with increased risk of upgrading from biopsy (Gleason 3 + 3) to prostatectomy (Gleason 7+). Now, using an evaluable subset of 111 patients with adjacent biopsy sections, we analyzed the association between PTEN deletion in cancer and the odds of upgrading by a highly sensitive and specific four-color FISH assay. We also compared the concordance of PTEN loss by IHC and PTEN deletion by FISH. PTEN deletion was found in 27 % (12/45) of upgraded cases compared with 11 % (7/66) of controls (P = 0.03). Cancers with PTEN deletions were more likely to be upgraded than those without deletions (adjusting for age odds ratio = 3.40, 95 % confidence interval 1.14-10.11). With respect to concordance, of 93 biopsies with PTEN protein detected by IHC, 89 (96 %) had no PTEN deletion by FISH, and of 18 biopsies without PTEN protein by IHC, 15 had homozygous or hemizygous PTEN deletion by FISH. Only 4 biopsies of the 93 (4 %) with PTEN protein intact had PTEN deletion by FISH. When the regions of uncertainty in these biopsies were systematically studied by FISH, intra-tumoral variation of PTEN deletion was found, which could account for variation in immunoreactivity. Thus, FISH provides a different approach to determining PTEN loss when IHC is uncertain. Both FISH and IHC are concordant, showing consistent positive associations between PTEN loss and upgrading.


Asunto(s)
Biomarcadores de Tumor/análisis , Hibridación Fluorescente in Situ , Fosfohidrolasa PTEN/metabolismo , Neoplasias de la Próstata/química , Neoplasias de la Próstata/patología , Anciano , Biopsia con Aguja , Humanos , Inmunohistoquímica/métodos , Hibridación Fluorescente in Situ/métodos , Masculino , Persona de Mediana Edad , Prostatectomía/métodos
9.
Nature ; 515(7526): 253-6, 2014 Nov 13.
Artículo en Inglés | MEDLINE | ID: mdl-25391963

RESUMEN

Whereas subduction recycling of oceanic lithosphere is one of the central themes of plate tectonics, the recycling of continental lithosphere appears to be far more complicated and less well understood. Delamination and convective downwelling are two widely recognized processes invoked to explain the removal of lithospheric mantle under or adjacent to orogenic belts. Here we relate oceanic plate subduction to removal of adjacent continental lithosphere in certain plate tectonic settings. We have developed teleseismic body wave images from dense broadband seismic experiments that show higher than expected volumes of anomalously fast mantle associated with the subducted Atlantic slab under northeastern South America and the Alboran slab beneath the Gibraltar arc region; the anomalies are under, and are aligned with, the continental margins at depths greater than 200 kilometres. Rayleigh wave analysis finds that the lithospheric mantle under the continental margins is significantly thinner than expected, and that thin lithosphere extends from the orogens adjacent to the subduction zones inland to the edges of nearby cratonic cores. Taking these data together, here we describe a process that can lead to the loss of continental lithosphere adjacent to a subduction zone. Subducting oceanic plates can viscously entrain and remove the bottom of the continental thermal boundary layer lithosphere from adjacent continental margins. This drives surface tectonics and pre-conditions the margins for further deformation by creating topography along the lithosphere-asthenosphere boundary. This can lead to development of secondary downwellings under the continental interior, probably under both South America and the Gibraltar arc, and to delamination of the entire lithospheric mantle, as around the Gibraltar arc. This process reconciles numerous, sometimes mutually exclusive, geodynamic models proposed to explain the complex oceanic-continental tectonics of these subduction zones.

10.
Am J Transplant ; 13(7): 1688-702, 2013 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-23750746

RESUMEN

Biliary epithelial cells (BEC) are important targets in some liver diseases, including acute allograft rejection. Although some injured BEC die, many can survive in function compromised states of senescence or phenotypic de-differentiation. This study was performed to examine changes in the phenotype of BEC during acute liver allograft rejection and the mechanism driving these changes. Liver allograft sections showed a positive correlation (p < 0.0013) between increasing T cell mediated acute rejection and the number of BEC expressing the senescence marker p21(WAF1/Cip) or the mesenchymal marker S100A4. This was modeled in vitro by examination of primary or immortalized BEC after acute oxidative stress. During the first 48 h, the expression of p21(WAF1/Cip) was increased transiently before returning to baseline. After this time BEC showed increased expression of mesenchymal proteins with a decrease in epithelial markers. Analysis of TGF-ß expression at mRNA and protein levels also showed a rapid increase in TGF-ß2 (p < 0.006) following oxidative stress. The epithelial de-differentiation observed in vitro was abrogated by pharmacological blockade of the ALK-5 component of the TGF-ß receptor. These data suggest that stress induced production of TGF-ß2 by BEC can modify liver allograft function by enhancing the de-differentiation of local epithelial cells.


Asunto(s)
Conductos Biliares Intrahepáticos/patología , Senescencia Celular , Células Epiteliales/patología , Rechazo de Injerto/patología , Trasplante de Hígado/patología , Enfermedad Aguda , Conductos Biliares Intrahepáticos/metabolismo , Biopsia , Western Blotting , Células Cultivadas , Densitometría , Ensayo de Inmunoadsorción Enzimática , Células Epiteliales/metabolismo , Regulación de la Expresión Génica , Rechazo de Injerto/genética , Rechazo de Injerto/metabolismo , Humanos , Inmunohistoquímica , Estrés Oxidativo/genética , ARN/genética , Reacción en Cadena en Tiempo Real de la Polimerasa , Factor de Crecimiento Transformador beta2/biosíntesis , Factor de Crecimiento Transformador beta2/genética , Trasplante Homólogo
11.
Nature ; 490(7419): 232-4, 2012 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-23060194

RESUMEN

The asymptotic-giant-branch star R Sculptoris is surrounded by a detached shell of dust and gas. The shell originates from a thermal pulse during which the star underwent a brief period of increased mass loss. It has hitherto been impossible to constrain observationally the timescales and mass-loss properties during and after a thermal pulse--parameters that determine the lifetime of the asymptotic giant branch and the amount of elements returned by the star. Here we report observations of CO emission from the circumstellar envelope and shell around R Sculptoris with an angular resolution of 1.3″. What was previously thought to be only a thin, spherical shell with a clumpy structure is revealed to also contain a spiral structure. Spiral structures associated with circumstellar envelopes have been previously seen, leading to the conclusion that the systems must be binaries. Combining the observational data with hydrodynamic simulations, we conclude that R Sculptoris is a binary system that underwent a thermal pulse about 1,800 years ago, lasting approximately 200 years. About 3 × 10(-3) solar masses of material were ejected at a velocity of 14.3 km s(-1) and at a rate around 30 times higher than the pre-pulse mass-loss rate. This shows that about three times more mass was returned to the interstellar medium during and immediately after the pulse than previously thought.

12.
Nature ; 472(7344): 461-5, 2011 Apr 28.
Artículo en Inglés | MEDLINE | ID: mdl-21525930

RESUMEN

The Colorado plateau is a large, tectonically intact, physiographic province in the southwestern North American Cordillera that stands at ∼1,800-2,000 m elevation and has long been thought to be in isostatic equilibrium. The origin of these high elevations is unclear because unlike the surrounding provinces, which have undergone significant Cretaceous-Palaeogene compressional deformation followed by Neogene extensional deformation, the Colorado plateau is largely internally undeformed. Here we combine new seismic tomography and receiver function images to resolve a vertical high-seismic-velocity anomaly beneath the west-central plateau that extends more than 200 km in depth. The upper surface of this anomaly is seismically defined by a dipping interface extending from the lower crust to depths of 70-90 km. The base of the continental crust above the anomaly has a similar shape, with an elevated Moho. We interpret these seismic structures as a continuing regional, delamination-style foundering of lower crust and continental lithosphere. This implies that Pliocene (2.6-5.3 Myr ago) uplift of the plateau and the magmatism on its margins are intimately tied to continuing deep lithospheric processes. Petrologic and geochemical observations indicate that late Cretaceous-Palaeogene (∼90-40 Myr ago) low-angle subduction hydrated and probably weakened much of the Proterozoic tectospheric mantle beneath the Colorado plateau. We suggest that mid-Cenozoic (∼35-25 Myr ago) to Recent magmatic infiltration subsequently imparted negative compositional buoyancy to the base and sides of the Colorado plateau upper mantle, triggering downwelling. The patterns of magmatic activity suggest that previous such events have progressively removed the Colorado plateau lithosphere inward from its margins, and have driven uplift. Using Grand Canyon incision rates and Pliocene basaltic volcanism patterns, we suggest that this particular event has been active over the past ∼6 Myr.

13.
Clin Genet ; 76(4): 326-31, 2009 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-19917019

RESUMEN

The purpose of this study was to examine the mental health needs of individuals at risk for adult onset hereditary disorder (AOHD) from the perspective of their genetic service providers, as it is unknown to what extent psychosocial services are required and being met. A mail-out survey was sent to 281 providers on the membership lists of the Canadian Association of Genetic Counsellors and the Canadian College of Medical Geneticists. The survey assessed psychosocial issues that were most commonly observed by geneticists, genetic counsellors (GCs), and nurses as well as availability and types of psychosocial services offered. Of the 129 respondents, half of genetic service providers reported observing signs of depression and anxiety, while 44% noted patients' concerns regarding relationships with family and friends. In terms of providing counselling to patients, as the level of psychological risk increased, confidence in dealing with these issues decreased. In addition, significantly more GCs reported that further training in psychosocial issues would be most beneficial to them if resources were available. As a feature of patient care, it is recommended that gene-based predictive testing include an integrative model of psychosocial services as well as training for genetic service providers in specific areas of AOHD mental health.


Asunto(s)
Servicios Genéticos , Servicios de Salud Mental/provisión & distribución , Ansiedad/genética , Ansiedad/terapia , Canadá , Consejo , Recolección de Datos , Trastorno Depresivo/genética , Trastorno Depresivo/terapia , Accesibilidad a los Servicios de Salud , Necesidades y Demandas de Servicios de Salud , Humanos , Trastornos Mentales/genética , Trastornos Mentales/terapia , Servicios de Salud Mental/estadística & datos numéricos
14.
Int Arch Med ; 2(1): 20, 2009 Jul 24.
Artículo en Inglés | MEDLINE | ID: mdl-19630960

RESUMEN

BACKGROUND: Physical trauma is an important cause of childhood morbidity and mortality in Africa. There are however, few community-based reports on the subject on the continent. The present study was conducted to explore school children's experience of physical trauma in a disadvantaged periurban area of Blantyre, in Malawi. METHODS: A cross sectional questionnaire study was carried out among school children in Ndirande-Blantyre, Malawi in 2004. Data were obtained to describe the following aspects of trauma experience: being a victim or observer of motor vehicular accidents involving pedestrians; history of falls from heights; and knowledge about road safety. Sex differences were determined for some of the variables in order to gain insights as to whether there is a difference in trauma experience between boys and girls. RESULTS: A total of 217 school children, 99 (45.6%) boys and 118 (54.4%) girls participated in the study. Eight of them reported to have ever been hit by a motor vehicle, 87 (40.1%) had witnessed a road accident where a pedestrian had been hit and 83 (38.2%) had witnessed a pedestrian they knew having been hit by a motor vehicle. Of those that reported to have ever been hit by motor vehicle, 2 (25%) reported that they had been hospitalized as a result of injury. With regard to falling from heights, 86 reported to have ever fallen from tree, 44 of these (51.2%) were injured from the fall and 14 (16.3%) were hospitalized as a result of injury sustained from the fall. Girls were more likely to fall from trees and getting injured as compared to males (p = 0.04 for both situations). Just under half (41.9%) of the study participants were able to report the correct procedure of crossing the road despite the fact that the majority (80%) reported having been taught road safety at home or school. CONCLUSION: Many school children in Blantyre, Malawi have been exposed to trauma either involving themselves or someone they observed. Prevention, including education, supervision and management of trauma must receive the necessary attention they deserve in terms of resources, surveillance and impact mitigation.

15.
J Anim Ecol ; 78(4): 880-9, 2009 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-19426254

RESUMEN

1. Movement patterns of predators should allow them to detect and respond to prey patches at different spatial scales, particularly through the adoption of area-restricted search (ARS) behaviour. Here we use fine-scale movement and activity data combined with first-passage time (FPT) analysis to examine the foraging strategy of northern gannets Morus bassanus in the western North Sea, and to test the following hypotheses: (i) birds adopt a hierarchical foraging strategy characterized by nested ARS behaviour; (ii) the locations and characteristics of ARS zones are strongly influenced by physical oceanography; (iii) the initiation of ARS behaviour is triggered by the detection and pursuit of prey; (iv) ARS behaviour is strongly linked to increased foraging effort, particularly within nested ARS areas. 2. Birds on 13 of 15 foraging trips adopted ARS behaviour at a scale of 9.1 +/- 1.9 km, and birds on 10 of these 13 trips adopted a second, nested ARS scale of 1.5 +/- 0.8 km, supporting hypothesis 1 above. ARS zones were located 117 +/- 55 km from the colony and over half were within 5 km of a tidal mixing front ~50 km offshore, supporting hypothesis 2 above. 3. The initiation of ARS behaviour was usually followed after only a short time interval (typically ~5 min) by the commencement of diving. Gannets do not dive until after they have located prey, and so this pattern strongly suggests that ARS behaviour was triggered by prey detection, supporting hypothesis 3 above. However, ~33% of dives in mixed coastal water and 16% of dives in stratified water were not associated with any detectable ARS behaviour. Hence, while ARS behaviour resulted from the detection and pursuit of prey, encounters with prey species did not inevitably induce ARS behaviour. 4. Following the initiation of ARS behaviour, dive rates were almost four times higher within ARS zones than elsewhere and almost three times higher in zones with nested ARS behaviour than in those without, supporting hypothesis 4 above and suggesting that the foraging success of birds was linked to their ability to match the hierarchical distribution of prey.


Asunto(s)
Charadriiformes/fisiología , Conducta Alimentaria/fisiología , Animales , Buceo , Telemetría
16.
Int Arch Med ; 2(1): 6, 2009 Mar 26.
Artículo en Inglés | MEDLINE | ID: mdl-19323817

RESUMEN

BACKGROUND: Pain is a leading symptom which influences patients to seek medical attention. The management of pain among patients attending in-patient care in southern African countries has been little described. Information regarding the prevalence of pain and the quality of its management may be useful in guiding clinical decisions, training of health workers and health care quality improvements. METHODS: A hospital-based audit was conducted to estimate the prevalence of pain and examine the quality of its management among patients admitted to adult medical wards at Queen Elizabeth Central Hospital (QECH), Blantyre, Malawi in 2004. Data were abstracted from ward charts of consecutive patients' who had been either been discharged or had died within a specified period. Characteristics of interest included; socio-demographic data, presence or absence of pain at admission, characterization or description of pain when present, and drug treatment given. Data were analyzed to obtain frequencies and proportions of the characteristics and assess the prevalence of pain and quality of care. RESULTS: A total of 121 patients' case notes were reviewed and the prevalence of pain was recorded for 91 (75.2%) of the patients. Clinicians had recorded pertinent information regarding pain management with the following frequency: pain severity or intensity 5/91 (5.5%), alleviating factors 5 (5.5%), pain radiation 7 (7.7%), exacerbating factors in 9 (9.9%) and periodicity in 43 (47.3%) of the cases. Males with pain were more than 3 times more likely to receive analgesic as compared to females, p < 0.01. Paracetamol was the commonest analgesic prescribed. CONCLUSION: Inadequate management of pain among patients attending medical wards at QECH was found. There is need for prospective studies to further characterize pain management and identify pain management gaps in Malawi. Interviews of clinicians and documentation of observations within clinical practice are likely to be of value.

17.
Malawi Med J ; 20(3): 80-5, 2008 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-19537404

RESUMEN

OBJECTIVES: We aimed to evaluate socio-demographic factors associated with HIV and syphilis seroreactivity in pregnant Malawians presenting for antenatal care in late third trimester of pregnancy. METHODS: Between December 2000 and March 2004 at Queen Elizabeth Central Hospital Blantyre, Malawi, we collected cross-sectional clinical and socioeconomic data from consenting women. HIV-1 status was determined using rapid HIV antibody tests and syphilis seroreactivity was determined using Rapid Plasma Reagin (RPR) and confirmed with Treponema pallidum hemagglutination assay (TPHA). RESULTS: Of 3,824 women screened for HIV, 1156 (30%) were HIV seropositive and 198 (5%) were RPR and TPHA seroreactive. In the multivariate analysis, HIV infection was positively associated with elevated socio-economic status, being formerly married, and age, but not with education level. HIV prevalence was lower in women of Yao ethnicity than in other women (OR: 0.78, 95%CI: 0.64-0.95). Increased maternal education was negatively associated with syphilis seroreactivity. CONCLUSIONS: The seroprevalence of HIV and syphilis among women attending the antenatal ward in Blantyre remains unacceptably high. Demographic correlates of HIV and syphilis infections were different. Our results demonstrate the need for better strategies to prevent HIV and syphilis in women and calls for optimizing antenatal syphilis screening and treatment in Malawi.


Asunto(s)
Infecciones por VIH/epidemiología , Seropositividad para VIH/epidemiología , Complicaciones Infecciosas del Embarazo/epidemiología , Sífilis/epidemiología , Adulto , Distribución por Edad , Demografía , Femenino , Infecciones por VIH/complicaciones , Infecciones por VIH/diagnóstico , Seropositividad para VIH/complicaciones , Seropositividad para VIH/diagnóstico , Seroprevalencia de VIH , VIH-1/inmunología , Pruebas de Hemaglutinación , Humanos , Malaui/epidemiología , Análisis Multivariante , Embarazo , Complicaciones Infecciosas del Embarazo/diagnóstico , Prevalencia , Factores de Riesgo , Factores Socioeconómicos , Encuestas y Cuestionarios , Sífilis/complicaciones , Sífilis/diagnóstico , Serodiagnóstico de la Sífilis , Adulto Joven
18.
Cochrane Database Syst Rev ; (4): CD006517, 2007 Oct 17.
Artículo en Inglés | MEDLINE | ID: mdl-17943914

RESUMEN

BACKGROUND: Highly active antiretroviral therapy has reduced the morbidity and mortality of patients with HIV/AIDS. A common first-line ART regimen includes a non-nucleoside reverse transcriptase inhibitor (NNRTI) and two nucleoside reverse transcriptase inhibitors (NRTIs). If treatment failure occurs, a change to second-line therapy is necessary. OBJECTIVES: This meta-analysis aimed to assess the optimum antiretroviral regimen for patients with HIV who fail first-line therapy (ART-naive) with d4T+3TC+NVP; d4T+3TC+EFV; ZDV+3TC+NVP; and ZDV+3TC+EFV. SEARCH STRATEGY: Electronic databases and conference proceedings were searched with relevant search terms without limits to language. SELECTION CRITERIA: Randomised controlled trials of HIV-infected adult patients administered second-line ART after virologic failure of a first-line regimen were included. The primary outcome measure included the proportion of patients achieving undetectable plasma HIV RNA concentration (viral load). Secondary outcome measures included change in mean CD4 cell count, clinical resolution of symptoms, rate of adverse events, rate of change in therapy for failure, rate of change in therapy for toxicity, and mortality. DATA COLLECTION AND ANALYSIS: Two authors assessed each reference for inclusion and exclusion criteria established a priori. Data were abstracted independently using a standardised abstraction form. MAIN RESULTS: Twenty-one records were identified in total, 6 of which were duplicates. None of the records met inclusion criteria. AUTHORS' CONCLUSIONS: There is insufficient evidence to evaluate second-line therapies in patients with HIV who fail first-line treatment with d4T+3TC+NVP; d4T+3TC+EFV; ZDV+3TC+NVP; and ZDV+3TC+EFV. Current recommendations are based on available resources and results from individualised treatment decisions based on resistance testing and clinician choice.


Asunto(s)
Fármacos Anti-VIH/uso terapéutico , Infecciones por VIH/tratamiento farmacológico , Inhibidores de la Transcriptasa Inversa/uso terapéutico , Quimioterapia Combinada , Humanos , Insuficiencia del Tratamiento
19.
Tree Physiol ; 27(1): 115-31, 2007 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-17169913

RESUMEN

We hypothesized that changes in net ecosystem productivity (NEP) during aging of coastal Douglas-fir (Pseudotsuga menziesii Mirb. Franco) stands could be explained by (1) changing nutrient uptake caused by different time scales for decomposition of fine, non-woody and coarse woody litter left after harvesting, (2) declines in canopy water status with lengthening of the water uptake pathway during bole and branch growth, and (3) increases in the ratio of autotrophic respiration (R (a)) to gross primary productivity (GPP) with phytomass accumulation. These hypotheses were implemented and tested in the mathematical model ecosys against eddy covariance (EC) measurements of forest CO(2) and energy exchange in a post-clearcut Douglas-fir chronosequence. Hypothesis 1 explained how (a) an initial rise in GPP observed during the first 3 years after clearcutting could be caused by nutrient mineralization from rapid decomposition of fine, non-woody litter with lower C:N ratios (assart effect), (b) a slower rise in GPP during the next 20 years could be caused by immobilization during later decomposition of coarse woody litter, and (c) a rapid rise in GPP between 20 and 40 years after clearcutting could be caused by nutrient mineralization with further decomposition of coarse woody litter and of its decomposition products. During periods (a) and (b), heterotrophic respiration (R (h)) from decomposition of fine and coarse litter greatly exceeded net primary productivity (NPP = GPP - R (a)) so that Douglas-fir stands were large sources of CO(2). During period (c), NPP exceeded R (h) so that these stands became large sinks for CO(2). Hypothesis 2 explained how declines in NPP during later growth in period (c) could be caused by lower hydraulic conductances in taller trees that would force lower canopy water potentials and hence greater sensitivity of stomatal conductances and CO(2) uptake to vapor pressure deficits. Enhanced sensitivity to vapor pressure deficits was also apparent in the EC measurements over the post-clearcut chronosequence. Hypothesis 3 did not contribute to the explanation of forest age effects on NEP.


Asunto(s)
Abies/fisiología , Ecosistema , Agricultura Forestal/métodos , Modelos Biológicos , Árboles/fisiología , Simulación por Computador , Nitrógeno/metabolismo , Temperatura , Factores de Tiempo , Agua/metabolismo
20.
Nature ; 438(7069): 842-5, 2005 Dec 08.
Artículo en Inglés | MEDLINE | ID: mdl-16341011

RESUMEN

Flood basalts appear to form during the initiation of hotspot magmatism. The Columbia River basalts (CRB) represent the largest volume of flood basalts associated with the Yellowstone hotspot, yet their source appears to be in the vicinity of the Wallowa Mountains, about 500 km north of the projected hotspot track. These mountains are composed of a large granitic pluton intruded into a region of oceanic lithosphere affinity. The elevation of the interface between Columbia River basalts and other geological formations indicates that mild pre-eruptive subsidence took place in the Wallowa Mountains, followed by syn-eruptive uplift of several hundred metres and a long-term uplift of about 2 km. The mapped surface uplift mimics regional topography, with the Wallowa Mountains in the centre of a 'bull's eye' pattern of valleys and low-elevation mountains. Here we present the seismic velocity structure of the mantle underlying this region and erosion-corrected elevation maps of lava flows, and show that an area of reduced mantle melt content coincides with the 200-km-wide topographic uplift. We conclude that convective downwelling and detachment of a compositionally dense plutonic root can explain the timing and magnitude of Columbia River basalt magmatism, as well as the surface uplift and existence of the observed melt-depleted mantle.

SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA