OALib Journal期刊

ISSN: 2333-9721




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匹配條件: “Jan H. Mol” ,找到相關結果約163084條。
Soil Erosion from Agriculture and Mining: A Threat to Tropical Stream Ecosystems
Karl M. Wantzen,Jan H. Mol
Agriculture , 2013, DOI: 10.3390/agriculture3040660
Abstract: In tropical countries soil erosion is often increased due to high erodibility of geologically old and weathered soils; intensive rainfall; inappropriate soil management; removal of forest vegetation cover; and mining activities. Stream ecosystems draining agricultural or mining areas are often severely impacted by the high loads of eroded material entering the stream channel; increasing turbidity; covering instream habitat and affecting the riparian zone; and thereby modifying habitat and food web structures. The biodiversity is severely threatened by these negative effects as the aquatic and riparian fauna and flora are not adapted to cope with excessive rates of erosion and sedimentation. Eroded material may also be polluted by pesticides or heavy metals that have an aggravating effect on functions and ecosystem services. Loss of superficial material and deepening of erosion gullies impoverish the nutrient and carbon contents of the soils; and lower the water tables; causing a “lose-lose” situation for agricultural productivity and environmental integrity. Several examples show how to interrupt this vicious cycle by integrated catchment management and by combining “green” and “hard” engineering for habitat restoration. In this review; we summarize current findings on this issue from tropical countries with a focus on case studies from Suriname and Brazil.
The fish fauna of Brokopondo Reservoir, Suriname, during 40 years of impoundment
Mol, Jan H.;Mérona, Bernard de;Ouboter, Paul E.;Sahdew, Shamita;
Neotropical Ichthyology , 2007, DOI: 10.1590/S1679-62252007000300015
Abstract: we investigated long-term changes in the fish fauna of brokopondo reservoir, suriname, the first large reservoir (1560 km2) that was created in tropical rainforest. before closure of the dam in 1964, the fish fauna of suriname river had 172 species, high diversity and high evenness. the riverine fauna was dominated by small-sized species, but no single species was dominant in numbers. large catfishes were dominant in biomass. species were evenly distributed over riverine habitats: rapids, tributaries and main channel. four years after closure of the dam, only 62 fish species were collected from brokopondo reservoir, but the composition of the fish fauna was still changing. the reservoir fauna in 1978 was very similar to the reservoir fauna in 2005, indicating that a stable equilibrium had been reached 14 years after closure of the dam. the reservoir fauna had 41 species, low diversity and low evenness. most species of suriname river and its tributaries with strict habitat requirements did not survive in brokopondo reservoir. fish community structure was different among four habitats of brokopondo reservoir. the open-water habitat (10 species) was dominated by the piscivores serrasalmus rhombeus, acestrorhynchus microlepis and cichla ocellaris and their prey bryconops melanurus and two hemiodus species. b. melanurus fed on zooplankton, culicinae pupae and terrestrial invertebrates. hemiodus fed on fine flocculent detritus, demonstrating that the detritus-based food chain was still important in late stages of reservoir development. serrasalmus rhombeus also fed on peccaries that drowned when swimming across the large reservoir in rough weather. the shore community (27 species) was dominated by seven cichlids, but early stages and juveniles of the open-water species s. rhombeus and b. melanurus also occurred in the shore habitat. fish biomass in the shore habitat was 66.5±59.9 kg ha-1. the cichlid geophagus surinamensis and the characid b. melanurus had a lower biomass
Three-terminal graphene single-electron transistor fabricated using feedback-controlled electroburning
Pawe? Puczkarski,Pascal Gehring,Chit S. Lau,Junjie Liu,Arzhang Ardavan,Jamie H. Warner,G. Andrew D. Briggs,Jan A. Mol
Physics , 2015, DOI: 10.1063/1.4932133
Abstract: We report room-temperature Coulomb blockade in a single layer graphene three-terminal single-electron transistor (SET) fabricated using feedback-controlled electroburning. The small separation between the side gate electrode and the graphene quantum dot results in a gate coupling up to 3 times larger compared to the value found for the back gate electrode. This allows for an effective tuning between the conductive and Coulomb blocked state using a small side gate voltage of about 1V. The technique can potentially be used in the future to fabricate all-graphene based room temperature single-electron transistors or three terminal single molecule transistors with enhanced gate coupling.
The LOFAR Beam Former: Implementation and Performance Analysis
Jan David Mol,John W. Romein
Physics , 2011,
Abstract: Traditional radio telescopes use large, steel dishes to observe radio sources. The LOFAR radio telescope is different, and uses tens of thousands of fixed, non-movable antennas instead, a novel design that promises ground-breaking research in astronomy. The antennas observe omnidirectionally, and sky sources are observed by signal-processing techniques that combine the data from all antennas. Another new feature of LOFAR is the elaborate use of software to do signal processing in real time, where traditional telescopes use custom-built hardware. The use of software leads to an instrument that is inherently more flexible. However, the enormous data rate (198 Gb/s of input data) and processing requirements compel the use of a supercomputer: we use an IBM Blue Gene/P. This paper presents a collection of new processing pipelines, collectively called the beam-forming pipelines, that greatly enhance the functionality of the telescope. Where our first pipeline could only correlate data to create sky images, the new pipelines allow the discovery of unknown pulsars, observations of known pulsars, and (in the future), to observe cosmic rays and study transient events. Unlike traditional telescopes, we can observe in hundreds of directions simultaneously. This is useful, for example, to search the sky for new pulsars. The use of software allows us to quickly add new functionality and to adapt to new insights that fully exploit the novel features and the power of our unique instrument. We also describe our optimisations to use the Blue Gene/P at very high efficiencies, maximising the effectiveness of the entire telescope. A thorough performance study identifies the limits of our system.
Protocol for the value of urodynamics prior to stress incontinence surgery (VUSIS) study: a multicenter randomized controlled trial to assess the cost effectiveness of urodynamics in women with symptoms of stress urinary incontinence in whom surgical treatment is considered
Sanne AL van Leijsen, Kirsten B Kluivers, Ben Mol, Suzan R Broekhuis, Fred L Milani, C Huub Vaart, Jan-Paul WR Roovers, Marlies Y Bongers, Jan den Boon, Wilbert A Spaans, Jan de Leeuw, Viviane Dietz, Jan H Kleinjan, Hans AM Br?lmann, Eveline J Roos, Judith Schaafstra, John PFA Heesakkers, Mark E Vierhout
BMC Women's Health , 2009, DOI: 10.1186/1472-6874-9-22
Abstract: The Value of Urodynamics prior to Stress Incontinence Surgery (VUSIS) study evaluates the positive and negative effects with regard to outcome, as well as the costs of urodynamics, in women with symptoms of SUI in whom surgical treatment is considered.A multicentre diagnostic cohort study will be performed with an embedded randomized controlled trial among women presenting with symptoms of (predominant) SUI.Urinary incontinence has to be demonstrated on clinical examination and/or voiding diary. Physiotherapy must have failed and surgical treatment needs to be under consideration.Patients will be excluded in case of previous incontinence surgery, in case of pelvic organ prolapse more than 1 centimeter beyond the hymen and/or in case of residual bladder volume of more than 150 milliliter on ultrasound or catheterisation.Patients with discordant findings between the diagnosis based on urodynamic investigation and the diagnosis based on their history, clinical examination and/or micturition diary will be randomized to operative therapy or individually tailored therapy based on all available information.Patients will be followed for two years after treatment by their attending urologist or gynaecologist, in combination with the completion of questionnaires.Six hundred female patients will be recruited for registration from approximately twenty-seven hospitals in the Netherlands. We aspect that one hundred and two women with discordant findings will be randomized.The primary outcome of this study is clinical improvement of incontinence as measured with the validated Dutch version of the Urinary Distress Inventory (UDI). Secondary outcomes of this study include costs, cure of incontinence as measured by voiding diary parameters, complications related to the intervention, re-interventions, and generic quality of life changes.Clinical Trials NCT00814749.Stress urinary incontinence (SUI) is a frequently occurring problem. The Health Council of the Netherlands estimated that
Modelling effects of acid deposition and climate change on soil and run-off chemistry at Risdalsheia, Norway
J. P. Mol-Dijkstra,H. Kros
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2001,
Abstract: Elevated carbon dioxide levels, caused by anthropogenic emissions of carbon dioxide to the atmosphere, and higher temperature may lead to increased plant growth and uptake of nitrogen, but increased temperature may lead to increased nitrogen mineralisation causing enhanced nitrogen leaching. The overall result of both counteracting effects is largely unknown. To gain insight into the long-term effects, the geochemical model SMART2 was applied using data from the catchment-scale experiments of the RAIN and CLIMEX projects, conducted on boreal forest ecosystems at Risdalsheia, southern Norway. These unique experiments at the ecosystem scale provide information on the short-term effects and interactions of nitrogen deposition and increased temperature and carbon dioxide on carbon and nitrogen cycling and especially the run-off chemistry. To predict changes in soil processes in response to climate change, the model was extended by including the temperature effect on mineralisation, nitrification, denitrification, aluminium dissolution and mineral weathering. The extended model was tested on the two manipulated catchments at Risdalsheia and long-term effects were evaluated by performing long-time runs. The effects of climate change treatment, which resulted in increased nitrogen fluxes at both catchments, were slightly overestimated by SMART2. The temperature dependency of mineralisation was simulated adequately but the temperature effect on nitrification was slightly overestimated. Monitored changes in base cation concentrations and pH were quite well simulated with SMART2. The long-term simulations indicate that the increase in nitrogen run-off is only a temporary effect; in the long-term, no effect on total nitrogen leaching is predicted. At higher deposition levels the temporary increase in nitrogen leaching lasts longer than at low deposition. Contrary to nitrogen leaching, temperature increase leads to a permanent decrease in aluminium concentrations and pH. Keywords: elevated carbon dioxide, temperature, forest ecosystem, modelling, nitrogen run-off.
Effect of remote ischemic conditioning on atrial fibrillation and outcome after coronary artery bypass grafting (RICO-trial)
Daniel Brevoord, Markus W Hollmann, Stefan G De Hert, Eric HPA van Dongen, Bram GADH Heijnen, Anton de Bruin, Noortje Tolenaar, Wolfgang S Schlack, Nina C Weber, Marcel GW Dijkgraaf, Joris R de Groot, Bas AJM de Mol, Antoine HG Driessen, Mona Momeni, Patrick Wouters, Stefaan Bouchez, Jan Hofland, Christan Lüthen, Tanja A Meijer-Treschan, Benedikt H Pannen, Benedikt Preckel
BMC Anesthesiology , 2011, DOI: 10.1186/1471-2253-11-11
Abstract: This study is a randomized, controlled, patient and investigator blinded multicenter trial. Elective CABG patients are randomized to one of the following four groups: 1) control, 2) remote ischemic preconditioning, 3) remote ischemic postconditioning, or 4) remote ischemic pre- and postconditioning. Remote conditioning is applied at the arm by 3 cycles of 5 minutes of ischemia and reperfusion. Primary endpoint is the incidence AF in the first 72 hours after surgery, detected using a Holter-monitor. Secondary endpoints include length-of-stay on the intensive care unit and in-hospital, and the occurrence of major adverse cardiovascular events at 30 days, 3 months and 1 year.Based on an expected incidence in the control group of 27%, 195 patients per group are needed to detect with 80% power a reduction by 45% following either pre- or postconditioning, while allowing for a 10% dropout and at an alpha of 0.05. With the combined intervention expected to be stronger, we need 75 patients in this group to detect a reduction in incidence of AF of 60%.The RICO-trial (the effect of Remote Ischemic Conditioning on atrial fibrillation and Outcome) is a randomized controlled multicenter trial, designed to investigate whether remote ischemic pre- and/or post-conditioning of the arm reduce the incidence of AF following CABG surgery.ClinicalTrials.gov under NCT01107184.It has been demonstrated previously that an organ can develop tolerance against ischemic stress by different interventions. In experimental studies, short periods (e.g., 3-5 minutes) of myocardial ischemia before the sustained ischemic period significantly reduced infarct size (early and late preconditioning) [1-3]. In addition, there is a significant amount of tissue that is damaged during early reperfusion, and it has been shown that staged reperfusion or short periods of ischemia (seconds to minutes) at the start of reperfusion, limits tissue damage (postconditioning) [4-6].Besides periods of ischemia, several drug
Induction of labour versus expectant monitoring in women with pregnancy induced hypertension or mild preeclampsia at term: the HYPITAT trial
Corine M Koopmans, Denise Bijlenga, Jan G Aarnoudse, Erik van Beek, Dick J Bekedam, Paul P van den Berg, Jan M Burggraaff, Erwin Birnie, Kitty WM Bloemenkamp, Addi P Drogtrop, Arie Franx, Christianne JM de Groot, Anjoke JM Huisjes, Anneke Kwee, Saskia le Cessie, Aren J van Loon, Ben WJ Mol, Joris AM van der Post, Frans JME Roumen, Hubertina CJ Scheepers, Marc EA Spaanderman, Rob H Stigter, Christine Willekes, Maria G van Pampus
BMC Pregnancy and Childbirth , 2007, DOI: 10.1186/1471-2393-7-14
Abstract: Women with a pregnancy complicated by pregnancy induced hypertension or mild preeclampsia at a gestational age between 36+0 and 41+0 weeks will be asked to participate in a multi-centre randomised controlled trial. Women will be randomised to either induction of labour or expectant management for spontaneous delivery. The primary outcome of this study is severe maternal morbidity, which can be complicated by maternal mortality in rare cases. Secondary outcome measures are neonatal mortality and morbidity, caesarean and vaginal instrumental delivery rates, maternal quality of life and costs. Analysis will be by intention to treat. In total, 720 pregnant women have to be randomised to show a reduction in severe maternal complications of hypertensive disease from 12 to 6%.This trial will provide evidence as to whether or not induction of labour in women with pregnancy induced hypertension or mild preeclampsia (nearly) at term is an effective treatment to prevent severe maternal complications.The protocol is registered in the clinical trial register number ISRCTN08132825.Pregnancy induced hypertension and preeclampsia are common complications of pregnancy [1]. In many cases, the clinical presentation is mild, consisting only of mild hypertension and/or mild proteinuria at term. In other cases however, severe maternal and fetal complications such as eclampsia, abruptio placentae, preterm delivery, the Hemolysis Elevated Liver enzymes and Low Platelet count syndrome (HELLP), fetal growth restriction or even intra-uterine fetal death may occur. Hypertensive disorders in pregnancy make a major contribution to maternal and neonatal mortality. In the Netherlands, hypertensive disorders in pregnancy are the largest single cause of maternal mortality [2].Approximately 10% to 15% of all pregnancies are complicated by hypertensive disorders. The vast majority of these cases occur after 32 weeks. The only causal treatment of the disease is delivery. In case of preterm pregnancies
Gene expression profiling of canine osteosarcoma reveals genes associated with short and long survival times
Gayathri T Selvarajah, Jolle Kirpensteijn, Monique E van Wolferen, Nagesha AS Rao, Hille Fieten, Jan A Mol
Molecular Cancer , 2009, DOI: 10.1186/1476-4598-8-72
Abstract: The 32 tumors were classified into two prognostic groups based on survival time (ST). They were defined as short survivors (dogs with poor prognosis: surviving fewer than 6 months) and long survivors (dogs with better prognosis: surviving 6 months or longer). Fifty-one transcripts were found to be differentially expressed, with common upregulation of these genes in the short survivors. The overexpressed genes in short survivors are associated with possible roles in proliferation, drug resistance or metastasis. Several deregulated pathways identified in the present study, including Wnt signaling, Integrin signaling and Chemokine/cytokine signaling are comparable to the pathway analysis conducted on human OS gene profiles, emphasizing the value of the dog as an excellent model for humans.A molecular-based method for discrimination of outcome for short and long survivors is useful for future prognostic stratification at initial diagnosis, where genes and pathways associated with cell cycle/proliferation, drug resistance and metastasis could be potential targets for diagnosis and therapy. The similarities between human and canine OS makes the dog a suitable pre-clinical model for future 'novel' therapeutic approaches where the current research has provided new insights on prognostic genes, molecular pathways and mechanisms involved in OS pathogenesis and disease progression.Naturally occurring cancer in the dog has been repeatedly emphasized as an excellent model for humans, because similarities in histology, tumor biology, disease progression and response to conventional therapies offer a unique translational opportunity in the broader prospect of cancer research. Since the release of the canine genome in 2005, dog spontaneous tumors have been in the spotlight for 'state-of-the-art' linkage to preclinical human cancer research, where strong similarities in cancer associated gene families were found when comparing the humans to dog [1]. Among the tumors of the dog, oste
Phenotypic plasticity in fish life-history traits in two neotropical reservoirs: Petit-Saut Reservoir in French Guiana and Brokopondo Reservoir in Suriname
Mérona, Bernard de;Mol, Jan;Vigouroux, Régis;Chaves, Paulo de Tarso;
Neotropical Ichthyology , 2009, DOI: 10.1590/S1679-62252009000400018
Abstract: fish species are known for their large phenotypic plasticity in life-history traits in relation to environmental characteristics. plasticity allows species to increase their fitness in a given environment. here we examined the life-history response of fish species after an abrupt change in their environment caused by the damming of rivers. two reservoirs of different age, both situated on the guiana shield, were investigated: the young petit-saut reservoir in french guiana (14 years) and the much older brokopondo reservoir in suriname (44 years). six life-history traits in 14 fish species were studied and compared to their value in the sinnamary river prior to the completion of petit-saut reservoir. the traits analyzed were maximum length, absolute and relative length at first maturation, proportion of mature oocytes in ripe gonad, batch fecundity and mean size of mature oocytes. the results revealed a general increase of reproductive effort. all species showed a decrease in maximum length. compared to the values observed before the dam constructions, eight species had larger oocytes and three species showed an increased batch fecundity. these observed changes suggest a trend towards a pioneer strategy. the changes observed in petit-saut reservoir also seemed to apply to the 30 years older brokopondo reservoir suggesting that these reservoirs remain in a state of immaturity for a long time.

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