1,370 research outputs found

    Spatial and temporal patterns of carabid activity-density in cereals do not explain levels of predation on weed seeds

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    Seed predation is an important component of seed mortality of weeds in agro-ecosystems, but the agronomic use and management of this natural weed suppression is hampered by a lack of insight in the underlying ecological processes. In this paper, we investigate whether and how spatial and temporal variation in activity-density of granivorous ground beetles (Coleoptera: Carabidae) results in a corresponding pattern of seed predation. Activity-density of carabids was measured by using pitfall traps in two organic winter wheat fields from March to July 2004. Predation of seeds (Capsella bursa-pastoris, Lamium amplexicaule, Poa annua and Stellaria media) was assessed using seed cards at the same sites and times. As measured by pitfall traps, carabids were the dominant group of insects that had access to the seed cards. In the field, predation of the four different species of seed was in the order: C. bursa-pastoris>P. annua>S. media>L. amplexicaule; and this order of preference was confirmed in the laboratory using the dominant species of carabid. On average, seed predation was higher in the field interior compared to the edge, whereas catches of carabids were highest near the edge. Weeks with elevated seed predation did not concur with high activity-density of carabids. Thus, patterns of spatial and temporal variation in seed predation were not matched by similar patterns in the abundance of granivorous carabid beetles. The lack of correspondence is ascribed to effects of confounding factors, such as weather, the background density of seeds, the composition of the carabid community, and the phenology and physiological state of the beetles. Our results show that differences in seed loss among weed species may be predicted from laboratory trials on preference. However, predator activity-density, as measured in pitfall traps, is an insufficient predictor of seed predation over time and space within a fiel

    Ecological agriculture in South-India : an agro-economic comparison and study of transition

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    This report describes two research programmes carried out on ecological agriculture in South-India. Experiences of twelve farmers in transition towards ecological agriculture are described and analysed. The comparative performance of seven farmer pairs, consisting of one ecological and one conventional reference farm, is analysed in relation to agronomic and economic performanc

    Was it worth it? Benefits of transcatheter aortic valve implantation from a patient's perspective:Benefits of transcatheter aortic valve implantation from a patient's perspective

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    OBJECTIVES: Transcatheter aortic valve implantation (TAVI) is an important treatment option for patients with severe aortic stenosis. To improve patient selection, shared decision‐making is recommended to elicit patients' treatment expectations and goals. We assessed patients' expectations and goals before TAVI treatment and whether these were met after treatment. Additionally, we evaluated how meeting these goals aligned with quality of life and functional recovery. DESIGN: A mixed method study. SETTING: An academic medical center. PARTICIPANTS: Seventy‐four patients undergoing TAVI between 2015 and 2017. MEASUREMENTS: Patients' expectations and goals were assessed qualitatively before treatment. Six to twelve months post procedure, quality of life was measured with the EuroQuol‐5D and any change in the number of dependencies in (instrumental) activities of daily living was assessed. RESULTS: Mean age of patients was 81.5 years, and 37.8% were male. Regaining the ability to engage in a specific hobby or activity was the most important treatment goal (33 patients, 54.1%), followed by reducing symptoms (19 patients 31.1%). 66.2% of patients stated that their treatment goal was met. Quality of life was higher in this group, as compared with patients who had not met their treatment goal. Twenty‐three patients (31.1%) showed functional improvement. CONCLUSION: TAVI patients were quite capable of eliciting treatment goals and a majority stated, after treatment, that these had been met patients' experience of treatment benefits regarding these goals had poor alignment with functional outcomes. This raises questions regarding relevant outcome measurements in this population, and could aid in improving shared decision‐making and patient selection for TAVI

    Delirium, functional decline and quality of life after transcatheter aortic valve implantation:An explorative study

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    Aim Transcatheter aortic valve implantation (TAVI) has become an important treatment option for older patients with severe aortic stenosis. However, not all patients benefit from this procedure in terms of functional outcome and quality of life. This complicates patient selection and shared decision-making. Postoperative delirium might negatively affect patient outcomes after TAVI. We therefore studied the potential relationship between postoperative delirium and functional outcome, and how this impacts quality of life after TAVI. Methods This was a prospective cohort study of 91 consecutive patients undergoing TAVI between 2015 and 2017 at an academic medical center. All patients underwent a Comprehensive Geriatric Assessment before TAVI. Delirium symptoms were assessed daily during hospitalization. Follow up was carried out between 6 and 12 months postprocedure. The primary outcome was functional decline or death at follow up. Secondarily, we measured quality of life at follow up. Results The incidence of postoperative delirium was 15.4%. In total, 38.5% of patients experienced functional decline, and 11.0% died during a median follow-up period of 7 months. Delirium resulted in a fourfold increased odds of the combined outcome of functional decline or death. Quality of life was lower in patients that experienced this outcome. Conclusion In a cohort of TAVI patients, functional decline or death was a frequent outcome in the first year postprocedure. Postoperative delirium increased the odds for this outcome substantially. This suggests that delirium risk should be an important factor to consider in shared decision-making for TAVI patients. Geriatr Gerontol Int 2020; center dot center dot: center dot center dot-center dot center dot

    The Rest-Frame Optical Luminosity Density, Color, and Stellar Mass Density of the Universe from z=0 to z=3

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    We present the evolution of the rest-frame optical luminosity density, of the integrated rest-frame optical color, and of the stellar mass density for a sample of Ks-band selected galaxies in the HDF-S. We derived the luminosity density in the rest-frame U, B, and V-bands and found that the luminosity density increases by a factor of 1.9+-0.4, 2.9+-0.6, and 4.9+-1.0 in the V, B, and U rest-frame bands respectively between a redshift of 0.1 and 3.2. We derived the luminosity weighted mean cosmic (U-B)_rest and (B-V)_rest colors as a function of redshift. The colors bluen almost monotonically with increasing redshift; at z=0.1, the (U-B)_rest and (B-V)_rest colors are 0.16 and 0.75 respectively, while at z=2.8 they are -0.39 and 0.29 respectively. We derived the luminosity weighted mean M/LV using the correlation between (U-V)_rest and log_{10} M/LV which exists for a range in smooth SFHs and moderate extinctions. We have shown that the mean of individual M/LV estimates can overpredict the true value by ~70% while our method overpredicts the true values by only ~35%. We find that the universe at z~3 had ~10 times lower stellar mass density than it does today in galaxies with LV>1.4 \times 10^{10} h_{70}^-2 Lsol. 50% of the stellar mass of the universe was formed by $z~1-1.5. The rate of increase in the stellar mass density with decreasing redshift is similar to but above that for independent estimates from the HDF-N, but is slightly less than that predicted by the integral of the SFR(z) curve.Comment: 19 pages, 12 figures, Accepted for Publication in the Dec. 20, 2003 edition of the Astrophysical Journal. Minor changes made to match the accepted version including short discussions on the effects of clustering and on possible systematic effects resulting from photometric redshift error

    On the discontinuous nature of the Mozambique Current

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    The concept of a spatially continuous western boundary current in the Mozambique Channel has historically been based on erroneous interpretations of ships' drift. Recent observations have demonstrated that the circulation in the Channel is instead dominated by anti-cyclonic eddies drifting poleward. It has therefore been suggested that no coherent Mozambique Current exists at any time. However, satellite and other observations indicate that a continuous current - not necessarily an inherent part of Mozambique Eddies - may at times be found along the full Mozambican shelf break. Using a high-resolution, numerical model we have demonstrated how such a feature may come about. In the model, a continuous current is a highly irregularly occurring event, occurring about once per year, with an average duration of only 9 days and with a vertical extent of about 800 m. Surface speeds may vary from 0.5 m/s to 1.5 m/s and the volume flux involved is about 10 Sv. The continuous current may occasionally be important for the transport of biota along the continental shelf and slope

    Huisartsgeneeskundige zorg in het verzorgingshuis

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    Een deel van de Nederlandse huisartsenzorg bestaat uit zorg voor ouderen in verzorgingshuizen. We vergelijken de huisartsenzorg aan patiënten in deze verzorgingshuizen met die aan leeftijdsgenoten die zelfstandig, buiten het verzorgingshuis, wonen. Omdat mensen langer zelfstandig wonen en de indicatiestelling voor plaatsing in een verzorgingshuis op basis van slecht functioneren in ADL gebeurt, verwachtten we een groep ouderen te vinden in het verzorgingshuis die meer complexe zorg behoeft van de huisarts. Het onderzoek is een ‘matched case-control’-studie in 3 Nederlandse huisartspraktijken in de periode 1/1/1998 tot 1/7/2004. De belangrijkste resultaten zijn dat de prevalentie van cognitieve problemen twee keer zo hoog en de prevalentie van depressie drie keer zo hoog is in de groep verzorgingshuisbewoners vergeleken met hun zelfstandig wonende leeftijdsgenoten. Problemen van het bewegingsapparaat worden ook veel gezien in de verzorgingshuizen. Chronische longproblemen, hart- en vaatziekten (excl. CVA) en urineweginfecties komen meer voor, maar CVA, diabetes en kanker komen juist evenveel voor binnen en buiten het verzorgingshuis. Geïnstitutionaliseerde ouderen gebruiken gemiddeld meer medicamenten tegelijkertijd. De conclusie is dat de huisarts in het verzorgingshuis te maken heeft met een specifieke kwetsbare groep ouderen waarbij de zorg niet beperkt is tot de behandeling van chronische aandoeningen, maar meer gericht is op het complexe samenspel van ziekte, afnemende functionele en cognitieve status en het levensperspectief van kwetsbare ouderen in het verzorgingshuis

    HI Narrow Line Absorption in Dark Clouds

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    We have used the Arecibo telescope to carry out an survey of 31 dark clouds in the Taurus/Perseus region for narrow absorption features in HI (λ\lambda 21cm) and OH (1667 and 1665 MHz) emission. We detected HI narrow self--absorption (HINSA) in 77% of the clouds that we observed. HINSA and OH emission, observed simultaneously are remarkably well correlated. Spectrally, they have the same nonthermal line width and the same line centroid velocity. Spatially, they both peak at the optically--selected central position of each cloud, and both fall off toward the cloud edges. Sources with clear HINSA feature have also been observed in transitions of CO, \13co, \c18o, and CI. HINSA exhibits better correlation with molecular tracers than with CI. The line width of the absorption feature, together with analyses of the relevant radiative transfer provide upper limits to the kinetic temperature of the gas producing the HINSA. Some sources must have a temperature close to or lower than 10 K. The correlation of column densities and line widths of HINSA with those characteristics of molecular tracers suggest that a significant fraction of the atomic hydrogen is located in the cold, well--shielded portions of molecular clouds, and is mixed with the molecular gas. The average number density ratio [HI]/[\h2] is 1.5×10−31.5\times10^{-3}. The inferred HI density appears consistent with but is slightly higher than the value expected in steady state equilibrium between formation of HI via cosmic ray destruction of H2_2 and destruction via formation of H2_2 on grain surfaces. The distribution and abundance of atomic hydrogen in molecular clouds is a critical test of dark cloud chemistry and structure, including the issues of grain surface reaction rates, PDRs, circulation, and turbulent diffusion.Comment: 40 pages, 10 figures, accepted by Ap
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