266 research outputs found
Biomass yield of silage maize, fertilizers efficiency, and soil properties under different soil-climate conditions and fertilizer treatments
We evaluated the efficiency (the netto agronomic efficiency – NAE, the physiological
efficiency – PE, and the apparent recovery efficiency – ARE) of farmyard manure (FYM) applied
alone, and together with mineral N (FYM+N), and NPK (FYM+NPK), on the biomass production
of silage maize at three localities (Caslav, Ivanovice, Lukavec) in the Czech Republic,
characterised by different soil-climate conditions. The effect of fertilizer treatment on soil
chemical properties was also analyzed. After four years of evaluation, the application of FYM
resulted in comparable biomass production as in the FYM+N, and FYM+NPK treatments,
showing the good ability of the mineralized FYM to provide enough nutrients during the growing
season. Increasing doses of applied nutrients were connected with higher biomass production.
However, no significant differences were recorded between fertilizer treatments. The efficiency
of applied nutrients was higher on soils of worst quality (sandy loamy Cambisol – Lukavec),
while lower on naturally fertile loamy degraded Chernozem (Ivanovice). But again, no significant
differences between the selected parameters were recorded. Although the application of mineral
fertilizers has not increased maize biomass yield significantly, they positively affected soil
chemical properties, mainly the soil concentration of P, K, Mg, and soil organic carbon content.
This shows the beneficial effect of the application of mineral fertilizers, especially in the Czech
Republic, where the application of mineral P and K decreased drastically during the last thirty
years
The response of a small stream in the Lesni potok forested catchment, central Czech Republic, to a short-term in-stream acidification
International audienceLesni Potok stream drains a forested headwater catchment in the central Czech Republic. It was artificially acidified with hydrochloric acid (HC1) for four hours to assess the role of stream substrate in acid-neutralisation and recovery. The pH was lowered from 4.7 to 3.2. Desorption of Ca and Mg and desorption or solution of Al dominated acid-neutralisation; Al mobilisation was more important later. The stream substrate released 4,542 meq Ca, 1,184 meq Mg, and 2,329 meq Al over a 45 m long and 1 m wide stream segment; smaller amounts of Be, Cd, Fe, and Mn were released. Adsorption of SO42- and desorption of F? occurred during the acidification phase of the experiment. The exchange reactions were rapidly reversible for Ca, Mg and SO42-; but not symmetric as the substrate resorbed 1083, 790 and 0 meq Ca, Mg, and Al, respectively, in a 4-hour recovery period. Desorption of SO42-; occurred during the resorption of Ca and Mg. These exchange and dissolution reactions delay acidification, diminish the pH depression and retard recovery from episodic acidification. The behaviour of the stream substrate-water interaction resembles that for soil?soil water interactions. A mathematical dynamic mass-balance based model, MASS (Modelling Acidification of Stream pediments), was developed which simulates the adsorption and desorption of base cations during the experiment and was successfully calibrated to the experimental data. Keywords: Al, Ca, Mg, base cations, acid-neutralisation, stream acidification, recovery, stream sediment, experiment, modelling, adsorption, desorption, adsorption, Czech Republic, Lesni Poto
Missing covariate data within cancer prognostic studies: a review of current reporting and proposed guidelines
Prognostic models play a crucial role in the clinical decision-making process. Unfortunately, missing covariate data impede the construction of valid and reliable models, potentially introducing bias, if handled inappropriately. The extent of missing covariate data within reported cancer prognostic studies, the current handling and the quality of reporting this missing covariate data are unknown. Therefore, a review was conducted of 100 articles reporting multivariate survival analyses to assess potential prognostic factors, published within seven cancer journals in 2002. Missing covariate data is a common occurrence in studies performing multivariate survival analyses, being apparent in 81 of the 100 articles reviewed. The percentage of eligible cases with complete data was obtainable in 39 articles, and was <90% in 17 of these articles. The methods used to handle incomplete covariates were obtainable in 32 of the 81 articles with known missing data and the most commonly reported approaches were complete case and available case analysis. This review has highlighted deficiencies in the reporting of missing covariate data. Guidelines for presenting prognostic studies with missing covariate data are proposed, which if followed should clarify and standardise the reporting in future articles
Dose-response relationship between ambulatory load magnitude and load-induced changes in COMP in young healthy adults
To determine the dose-response relationship between ambulatory load magnitude during a walking stress test and load-induced changes in serum concentration of cartilage oligomeric matrix protein (sCOMP) in healthy subjects.; sCOMP was assessed before and after a 30-min walking stress test performed on three test days by 24 healthy volunteers. In each walking stress test, one of three ambulatory loads was applied in a block randomized crossover design: normal body weight (BW) (100%BW = normal load); reduced BW (80%BW = reduced load); increased BW (120%BW = increased load). Knee kinematics and ground reaction force (GRF) were measured using an inertial sensor gait analysis system and a pressure plate embedded in the treadmill.; Load-induced increases in sCOMP rose with increasing ambulatory load magnitude. Mean sCOMP levels increased immediately after the walking stress test by 26.8 ± 12.8%, 28.0 ± 13.3% and 37.3 ± 18.3% for the reduced, normal or increased load condition, respectively. Lower extremity kinematics did not differ between conditions.; The results of this study provide important evidence of a dose-response relationship between ambulatory load magnitude and load-induced changes in sCOMP. Our data suggests that in normal weight persons sCOMP levels are more sensitive to increased than to reduced load. The experimental framework presented here may form the basis for studying the relevance of the dose-response relationship between ambulatory load magnitude and load-induced changes in biomarkers involved in metabolism of healthy articular cartilage and after injury
Vascular grading of angiogenesis: prognostic significance in breast cancer
The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11 years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers was moderately reproduced (κ = 0.59). Vascular grade was significantly associated with axillary node involvement, tumour size, malignancy grade, oestrogen receptor status and histological type. In univariate analyses vascular grade significantly predicted recurrence free survival and overall survival for all patients (P< 0.0001), node-negative patients (P< 0.0001) and node-positive patients (P< 0.0001). Cox multivariate regression analysis showed that vascular grading contributed with independent prognostic value in all patients (P< 0.0001). A prognostic index including the vascular grade had clinical impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer. © 2000 Cancer Research Campaig
Comparison of techniques for handling missing covariate data within prognostic modelling studies: a simulation study
Background: There is no consensus on the most appropriate approach to handle missing covariate data within prognostic modelling studies. Therefore a simulation study was performed to assess the effects of different missing data techniques on the performance of a prognostic model.
Methods: Datasets were generated to resemble the skewed distributions seen in a motivating breast cancer example. Multivariate missing data were imposed on four covariates using four different mechanisms; missing completely at random (MCAR), missing at random (MAR), missing not at random (MNAR) and a combination of all three mechanisms. Five amounts of incomplete cases from 5% to 75% were considered. Complete case analysis (CC), single imputation (SI) and five multiple imputation (MI) techniques available within the R statistical software were investigated: a) data augmentation (DA) approach assuming a multivariate normal distribution, b) DA assuming a general location model, c) regression switching imputation, d) regression switching with predictive mean matching (MICE-PMM) and e) flexible additive imputation models. A Cox proportional hazards model was fitted and appropriate estimates for the regression coefficients and model performance measures were obtained.
Results: Performing a CC analysis produced unbiased regression estimates, but inflated standard errors, which affected the significance of the covariates in the model with 25% or more missingness. Using SI, underestimated the variability; resulting in poor coverage even with 10% missingness. Of the MI approaches, applying MICE-PMM produced, in general, the least biased estimates and better coverage for the incomplete covariates and better model performance for all mechanisms. However, this MI approach still produced biased regression coefficient estimates for the incomplete skewed continuous covariates when 50% or more cases had missing data imposed with a MCAR, MAR or combined mechanism. When the missingness depended on the incomplete covariates, i.e. MNAR, estimates were biased with more than 10% incomplete cases for all MI approaches.
Conclusion: The results from this simulation study suggest that performing MICE-PMM may be the preferred MI approach provided that less than 50% of the cases have missing data and the missing data are not MNAR
The impact of post-procedural complications on reimbursement, length of stay and mechanical ventilation among patients undergoing transcatheter aortic valve implantation in Germany
BACKGROUND: The impact of various post-procedural complications after transcatheter aortic valve implantation (TAVI) on resource use and their consequences in the German reimbursement system has still not been properly quantified. METHODS: In a retrospective observational study, we use data from the German DRG statistic on patient characteristics and in-hospital outcomes of all isolated TAVI procedures in 2013 (N = 9147). The impact of post-procedural complications on reimbursement, length of stay and mechanical ventilation was analyzed using both unadjusted and risk-adjusted linear and logistic regression analyses. RESULTS: A total of 235 (2.57%) strokes, 583 (6.37%) bleeding events, 474 (5.18%) cases of acute kidney injury and 1428 (15.61%) pacemaker implantations were documented. The predicted reimbursement of an uncomplicated TAVI procedure was €33,272, and bleeding events were associated with highest additional reimbursement (€12,839, p 48 h: OR 6.93, p 48 h: OR 5.73, p < 0.001). Pacemaker implantations, in contrast, were associated with comparably small increases in reimbursement (€662, p = 0.006) and length of stay (3.54 days, p = 0.006) and no impaired likelihood of mechanical ventilation more than 48 h (OR 1.22, p = 0.156). Interestingly, these complication-related consequences remain mostly unchanged after baseline risk-adjustment. CONCLUSIONS: Post procedural complications such as bleeding events, acute kidney injuries and strokes are associated with increased resource use and substantial amounts of additional reimbursement in Germany, which has important implications for decision making outside of the usual clinical sphere
Inter-rater agreement and reliability of the COSMIN (COnsensus-based Standards for the selection of health status Measurement Instruments) Checklist
<p>Abstract</p> <p>Background</p> <p>The COSMIN checklist is a tool for evaluating the methodological quality of studies on measurement properties of health-related patient-reported outcomes. The aim of this study is to determine the inter-rater agreement and reliability of each item score of the COSMIN checklist (n = 114).</p> <p>Methods</p> <p>75 articles evaluating measurement properties were randomly selected from the bibliographic database compiled by the Patient-Reported Outcome Measurement Group, Oxford, UK. Raters were asked to assess the methodological quality of three articles, using the COSMIN checklist. In a one-way design, percentage agreement and intraclass kappa coefficients or quadratic-weighted kappa coefficients were calculated for each item.</p> <p>Results</p> <p>88 raters participated. Of the 75 selected articles, 26 articles were rated by four to six participants, and 49 by two or three participants. Overall, percentage agreement was appropriate (68% was above 80% agreement), and the kappa coefficients for the COSMIN items were low (61% was below 0.40, 6% was above 0.75). Reasons for low inter-rater agreement were need for subjective judgement, and accustom to different standards, terminology and definitions.</p> <p>Conclusions</p> <p>Results indicated that raters often choose the same response option, but that it is difficult on item level to distinguish between articles. When using the COSMIN checklist in a systematic review, we recommend getting some training and experience, completing it by two independent raters, and reaching consensus on one final rating. Instructions for using the checklist are improved.</p
Test-retest repeatability of child's respiratory symptoms and perceived indoor air quality - comparing self-and parent-administered questionnaires
Background: Questionnaires can be used to assess perceived indoor air quality and symptoms in schools. Questionnaires for primary school aged children have traditionally been parent-administered, but self-administered questionnaires would be easier to administer and may yield as good, if not better, information. Our aim was to compare the repeatability of self- and parent-administered indoor air questionnaires designed for primary school aged pupils. Methods: Indoor air questionnaire with questions on child's symptoms and perceived indoor air quality in schools was sent to parents of pupils aged 7-12 years in two schools and again after two weeks. Slightly modified version of the questionnaire was administered to pupils aged 9-12 years in another two schools and repeated after a week. 351 (52%) parents and 319 pupils (86%) answered both the first and the second questionnaire. Test-retest repeatability was assessed with intra-class correlation (ICC) and Cohen's kappa coefficients (k). Results: Test-retest repeatability was generally between 0.4-0.7 (ICC; k) in both self-and parent-administered questionnaire. In majority of the questions on symptoms and perceived indoor air quality test-retest repeatability was at the same level or slightly better in self-administered compared to parent-administered questionnaire. Agreement of self-and parent administered questionnaires was generally <0.4 (ICC; k) in reported symptoms and 0.4-0.6 (ICC; k) in perceived indoor air quality. Conclusions: Children aged 9-12 years can give as, or even more, repeatable information about their respiratory symptoms and perceived indoor air quality than their parents. Therefore, it may be possible to use self-administered questionnaires in future studies also with children.Peer reviewe
Assessing the information desire of patients with advanced cancer by providing information with a decision aid, which is evaluated in a randomized trial: a study protocol
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95653.pdf (publisher's version ) (Open Access)BACKGROUND: There is a continuing debate on the desirability of informing patients with cancer and thereby involving them in treatment decisions. On the one hand, information uptake may be hampered, and additional stress could be inflicted by involving these patients. On the other hand, even patients with advanced cancer desire information on risks and prognosis. To settle the debate, a decision aid will be developed and presented to patients with advanced disease at the point of decision making. The aid is used to assess the amount of information desired. Factors related to information desire are explored, as well as the ability of the medical oncologist to judge the patient's information desire. The effects of the information on patient well-being are assessed by comparing the decision aid group with a usual care group. METHODS/DESIGN: This study is a randomized controlled trial of patients with advanced colorectal, breast, or ovarian cancer who have started treatment with first-line palliative chemotherapy. The trial will consist of 100 patients in the decision aid group and 70 patients in the usual care group. To collect complete data of 170 patients, 246 patients will be approached for the study. Patients will complete a baseline questionnaire on sociodemographic data, well-being measures, and psychological measures, believed to predict information desire. The medical oncologist will judge the patient's information desire. After disease progression is diagnosed, the medical oncologist offers the choice between second-line palliative chemotherapy plus best supportive care (BSC) and BSC alone. Randomization will take place to determine whether patients will receive usual care (n = 70) or usual care and the decision aid (n = 100). The aid offers information about the potential risks and benefits of both treatment options, in terms of adverse events, tumour response, and survival. Patients decide for each item whether they desire the information or not. Two follow-up questionnaires will evaluate the effect of the decision aid. DISCUSSION: This study attempts to settle the debate on the desirability of informing patients with cancer. In contrast to several earlier studies, we will actually deliver information on treatment options to patients at the point of decision making
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