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Search Results: 1 - 10 of 35129 matches for " van der Fels-Klerx "
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Modeling cadmium in the feed chain and cattle organs
van der Fels-Klerx, I.,R?mkens, P.,Franz, E.,van Raamsdonk, L.
Biotechnologie, Agronomie, Société et Environnement , 2011,
Abstract: The objectives of this study were to estimate cadmium contamination levels in different scenarios related to soil characteristics and assumptions regarding cadmium accumulation in the animal tissues, using quantitative supply chain modeling. The model takes into account soil cadmium levels, soil pH, soil-to-plant transfer, animal consumption patterns, and transfer into animal organs (liver and kidneys). The model was applied to cattle up to the age of six years which were fed roughage (maize and grass) and compound feed. Cadmium content in roughage and cadmium intake by cattle were calculated for six different (soil) scenarios varying in soil cadmium levels and soil pH. For each of the six scenarios, the carry-over of cadmium from intake into the cattle organs was estimated applying two model assumptions, i.e., linear accumulation and a steady state situation. The results showed that only in the most extreme soil scenario (cadmium level 2.5 mg.kg-1, pH 4.5), cadmium exceeded the EC maximum tolerated level in roughage. Assuming linear accumulation, cadmium levels in organs of cattle up to six years of age, ranged from 0.37-4.03 mg.kg-1 of fresh weight for kidneys and from 0.07 to 0.77 mg.kg-1 of fresh weight for livers. The maximum tolerated levels in one or both organs were exceeded in several scenarios. When considering organ excretion of cadmium, internal cadmium levels in organs were approximately one order of magnitude lower as compared to the results of the linear accumulation model. In this case only in the most extreme soil scenario, the maximum tolerated level in the kidney was exceeded. It was concluded that the difference between the two assumptions (linear model versus a steady state situation to estimate cadmium carry-over in cattle) is negligible in the animal's first five years of life, but will become relevant at higher ages. For the current case, the linear approach is a good descriptor for worst case situations. Furthermore, this study showed that quantitative supply chain modeling is an effective tool in assessing whether or not a specific combination of soil properties would lead to unacceptable contaminant levels in feedstuffs and animal products in the view of animal and human health.
Impact of Climate Change Effects on Contamination of Cereal Grains with Deoxynivalenol
H. J. Van der Fels-Klerx, Esther D. van Asselt, Marianne S. Madsen, J?rgen E. Olesen
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0073602
Abstract: Climate change is expected to aggravate feed and food safety problems of crops; however, quantitative estimates are scarce. This study aimed to estimate impacts of climate change effects on deoxynivalenol contamination of wheat and maize grown in the Netherlands by 2040. Quantitative modelling was applied, considering both direct effects of changing climate on toxin contamination and indirect effects via shifts in crop phenology. Climate change projections for the IPCC A1B emission scenario were used for the scenario period 2031-2050 relative to the baseline period of 1975-1994. Climatic data from two different global and regional climate model combinations were used. A weather generator was applied for downscaling climate data to local conditions. Crop phenology models and prediction models for DON contamination used, each for winter wheat and grain maize. Results showed that flowering and full maturity of both wheat and maize will advance with future climate. Flowering advanced on average 5 and 11 days for wheat, and 7 and 14 days for maize (two climate model combinations). Full maturity was on average 10 and 17 days earlier for wheat, and 19 and 36 days earlier for maize. On the country level, contamination of wheat with deoxynivalenol decreased slightly, but not significantly. Variability between regions was large, and individual regions showed a significant increase in deoxynivalenol concentrations. For maize, an overall decrease in deoxynivalenol contamination was projected, which was significant for one climate model combination, but not significant for the other one. In general, results disagree with previous reported expectations of increased feed and food safety hazards under climate change. This study illustrated the relevance of using quantitative models to estimate the impacts of climate change effects on food safety, and of considering both direct and indirect effects when assessing climate change impacts on crops and related food safety hazards.
Additional Arguments for a Correction of the Debye-Hückel, Maxwell-Boltzmann Equations for Dilute Electrolyte Equilibria  [PDF]
Peter van der Weg
American Journal of Analytical Chemistry (AJAC) , 2018, DOI: 10.4236/ajac.2018.99032
Abstract: Peter Debye and Erich Hückel had developed a theory for the ionic activity coefficients in dilute solutions of strong electrolytes some 95 years ago [1]. Their limiting law still stands and is confirmed as close to reality in many experiments. In a previous article [2], it is shown that these limiting activity coefficients arise because the electrical contribution in the electrochemical potential of ionic species is overestimated traditionally with a factor 2. The smaller value removes inconsistencies in the models and complies better with the basic electrostatic principles. In this article further evidence is given in support of this alternative description. As consequence the dilute activity coefficients become unity, e.g. are removed, which means that the electrochemical potential of ions in dilute solutions is expressed directly in concentration, instead of activity, which simplifies modelling in such dilute solutions.
A method to study the effect of bronchodilators on smoke retention in COPD patients: study protocol for a randomized controlled trial
WD van Dijk, PTJ Scheepers, R Cremers, JWM Lenders, W Klerx, C van Weel, TRJ Schermer, Y Heijdra
Trials , 2011, DOI: 10.1186/1745-6215-12-37
Abstract: The design consists of a double-blinded, placebo-controlled, randomised crossover trial, in which 40 COPD patients smoke cigarettes during both undilated and maximal bronchodilated conditions. Our primary outcome is the retention of cigarette smoke, expressed as tar and nicotine weight. The inhaled tar weights are calculated from the correlated extracted nicotine weights in cigarette filters, whereas the exhaled weights are collected on Cambridge filters. We established the inhaled weight calculations by a pilot study, that included paired measurements from several smoking regimes. Our study protocol is approved by the local accredited medical review ethics committee.Our study is currently in progress. The pilot study revealed valid equations for inhaled tar and nicotine, with an R2 of 0.82 and 0.74 (p < 0.01), respectively. We developed a method to study pulmonary smoke retentions in COPD patients under the influence of bronchodilation which may affect smoking-related disease. This trial will provide fundamental knowledge about the (cardiovascular) safety of bronchodilators in patients with COPD who persist in their habit of cigarette smoking.ClinicalTrials.gov: NCT00981851Chronic obstructive pulmonary disease (COPD) is a common chronic disease, characterised by poorly reversible and progressive airflow obstruction. A substantial fraction of COPD-related mortality and morbidity is due to cardiovascular disease [1-3]. Both diseases share an important risk factor: smoking. Cigarette smoking causes over 80% of COPD, whereas 20% of cardiovascular mortality is attributable to smoking [4,3,6]. Cessation of cigarette smoking is an important prognostic factor in patients with COPD and cardiovascular disease. Besides, smoking cessation is essential in preventing development of cardiovascular disease in all people, including COPD patients. However, half of COPD patients are persistent smokers [7,4,9,5].Meanwhile, the cornerstone of pharmaceutical treatment of COPD symptoms i
Chest Wall Reconstruction with Precontoured Locking Plate Proof of Concept  [PDF]
Elmer Lodder, Maarten van der Elst
Journal of Cancer Therapy (JCT) , 2010, DOI: 10.4236/jct.2010.13021
Abstract: Complications after chest wall resection are common and are reported to occur in approximately 40% of patients. The most frequent complications are respiratory or wound complications. Restoring rib continuity after a resection is likely to prevent respiratory complications. However many patients remain painful after a reconstruction. This article describes a new technique using a titanium alloy precontoured locking plate and locking screws to reconstruct the chest wall after resection of the 7th rib on the left.
Diminishing demandingness of parents; children with recurrent infections  [PDF]
Ellen van der Gaag, Miriam Münow
Health (Health) , 2012, DOI: 10.4236/health.2012.48077
Abstract: Background and Method: Parenting and parenting styles are in favor of authoritative parents compared with non-authoritative parents. These parents display higher levels of both responsiveness and demandingness. We studied the aspect of demandingness using a questionnaire aimed at children aged between 1 and 4 years. 82 Children with recurrent respiratory infections (RRI) and 399 control children were included. Results: Parents of RRI children regulated the quantitative dietary intake of their child less; likewise they gave less stimulation to their children to eat. They also taught their children less on what they can or cannot touch and they argued more with their children (all p < 0.05). However, when it comes to simple rules like watching television or not, the parents of RRI children were very clear. There were however no differences in rules about television watching, computer time or bedtimes. Conclusions: Our study shows that parents of children with RRI are less demanding in complex pedagogic situations that ask for creativity from the parents. However, they are demanding with respect to simple rules. We found no child factors that could explain why children give their parents a hard time. We hypothesize that the parents of RRI children could be less capable of handling complex pedagogic situations (even more complicated by the infections) instead of being unwilling.
Classification of Toxic Cyanobacterial Blooms by Fourier-Transform Infrared Technology (FTIR)  [PDF]
Gabriel Kenne, Deon van der Merwe
Advances in Microbiology (AiM) , 2013, DOI: 10.4236/aim.2013.36A001
Abstract: Cyanobacteria are gram-negative photosynthetic bacteria capable of producing toxins responsible for morbidity and mortality in humans and domestic animals. They are capable of forming concentrated blooms, referred to as harmful algal blooms (HABs). Characterization of HABs is necessary to reduce risks from human and animal exposures to toxins. Current methods used to classify cyanobacteria and cyanotoxins have limitations related to time, analyst skills, and cost. Fourier-Transform Infrared Spectroscopy (FTIR) is a potential tool for rapid, robust cyanobacterial classification that is not limited by these factors. To examine the practicality of this method, library screening with default software algorithms was performed on HAB samples, followed by principle component cluster analyses and dendrogram analysis of samples meeting minimum quality requirements. Two tested spectrometers and software packages were successful at distinguishing cyanobacteria from green algae. Principle component cluster analysis and dendrogram analysis also resulted in clear differentiation between cyanobacteria and green algae. While these methods cannot be used independently to fully characterize HABs, they show the potential and practicality of FTIR as a screening tool.
Tortuguero National Park, Costa Rica: Baseline CO2 Emissions from Boat Tours into the Channels System  [PDF]
Irene Alvarado-Van der Laat
Low Carbon Economy (LCE) , 2014, DOI: 10.4236/lce.2014.51003

Tortuguero National Park located on the Caribbean coast of Costa Rica is only accessible by boat or air and attracts an average of 130,000 visitors yearly. The main activity of the park is the turtle nesting and hatching along the beaches as well as the observation of wildlife in the channel sys- tem. This makes it important to study the CO2 emitted by the tours operating in the park. To cal- culate these emissions researchers gathered data on engine type, horsepower and duration of idle while boats waited to buy tickets at the park entrance. The study found that tour operators emit- ted a minimum of 5.5 tons of CO2 per year into the atmosphere and water. It is likely that the park is more polluted than immediately evident.

Hospitalization Can Correct Behavioral Feeding Disorders in Children by Resetting the Pedagogic Climate  [PDF]
Ellen van der Gaag, Miriam Münow
Open Journal of Pediatrics (OJPed) , 2014, DOI: 10.4236/ojped.2014.42019

Background: Behavioral feeding disorders are common among children, which sometimes become progressive, and consequently, children may refuse to eat anything. Parents have lots of difficulties to reset such a disturbed eating pattern. The aim of this study was to perform an analysis of clinical intervention in behavioral feeding disorders in young children. Methods: We conducted a retrospective analysis of data of 28 children aged 1 - 9 years with behavioral feeding disorders. A pediatrician and pediatric social worker conducted the training in two groups: outpatient or inpatient setting. Both groups were treated with parental education and guidance. The inpatient group also had a temporarily (2 weeks) resetting of the pedagogic climate in a pediatric ward of a general hospital under guidance of a pediatric social worker. Results: Almost all parents were inconsistent in applying appropriate behavioral contingencies during meals. Eleven patients followed 8 months of outpatient treatment and 25 patients followed 2 weeks of inpatient treatment. The overall success rate of outpatient treatment after 2 weeks was 18%, and that of inpatient treatment after 8 months was 88%. The corrected relapse rates are 18% and 56% respectively after 6 months. Conclusion: Short clinical intervention in a structured pedagogic environment is a successful treatment in behavioral feeding disorders. Herewith, pediatricians have a powerful tool for treating behavioral feeding disorders by temporarily resetting and changing the pedagogic climate.

A Single Center Retrospective Analysis of Kraske’s Transsacral Approach: A Review  [PDF]
Cédric Bouts, Kurt Van der Speeten
Surgical Science (SS) , 2014, DOI: 10.4236/ss.2014.510070
Abstract: Aim: Presacral lesions are uncommon and represent a diagnostic and surgical challenge. The aim of this study is to present our experience with Kraske’s transsacral resection and to review current literature. Methods: Seven patients who had a transsacral resection between 2001 and 2013 were reviewed retrospectively. Results: Two men and five women with a mean age of 39 (range 17 - 60) years were diagnosed with a presacral lesion. The clinical presentation was nonspecific; pain was the most common symptom. All lesions were palpable on digital rectal examination. Magnetic resonance imaging (MRI) was necessary to assess the tumor’s extent, biological behavior and relationship to adjacent structures. MRI predicted malignancy with 100% accuracy. All lesions were located below S3 and underwent a transsacral resection. Pathological examination revealed four tailgut cysts, two epidermoid cysts and one chordoma. Postoperative complications included wound infections (two cases) and spasms of the gluteus muscle (one case). We reported no recurrence or mortality. Conclusion: Clinical awareness, the use of MRI in the routine work-up and avoidance of an incisional biopsy result in a good outcome after surgical resection of presacral lesions. Kraske’s approach can be used for presacral lesions below S3, resulting in low morbidity, no recurrence and no mortality.
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