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Asian Journal of Andrology 2010年第1期12卷 47-58页

作者： roelof Menkveld Andrology Laboratory Department of Obstetrics and Gynaecology Tygerberg Academic Hospital and University ofStellenbosch Tygerberg 7505 South Africa

The very low cut-off value for sperm morphology of 4% morphologically normal spermatozoa, as proposed in the new edition of the World Health Organization （WHO） manual on semen analysis, is in agreement with recently published values and reflects the trend of a decline in reported mean values for normal sperm morphology. The reduced value for morphologically normal spermatozoa over the years may be due to several factors. The first is the introduction of strict criteria for the evaluation of sperm morphology. Other reasons may include the introduction of additional criteria for sperm morphology abnormalities and the suggested decrease in semen parameters because of increasing negative environmental influences. Although on its own the newly proposed very low normal value may not provide the strong predictive value for a males＇ fertility potential, as originally reported for sperm morphology evaluated according to strict criteria, a good predictive value can still be obtained if the holistic, strict approach for sperm morphology evaluation is followed together with additional sperm morphology parameters now available, because certain morphology patterns and sperm abnormalities are now known to be of strong prognostic value. In addition, better international standardization of the technical methodology, consensus on the interpretation of sperm morphology evaluation criteria and standardized international external quality control （EQC） schemes, are of utmost importance to maintain the good predictive value of sperm morphology.

关键词： male fertility potential normal cut-offvalues semen analysis sperm morphology evaluation strict criteria WHO manual

Measurement and significance of sperm morphology

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Asian Journal of Andrology 2011年第1期13卷 59-68页

作者： roelof Menkveld Cas AG Holleboom Johann PT Rhemrev Andrology Laboratory Department of Obstetrics and Gynaecology Tygerberg Academic Hospital and University of Stellenbosch Tygerberg 7505 South Africa Department of Obstetrics and Gynecology Bronovo Hospital The Hague 2597AX The Netherlands

The measurement or evaluation and clinical significance of human sperm morphology has always been and still is a controversial aspect of the semen analysis for the determination of a male＇s fertility potential. In this review the background of the development of the evaluation criteria for sperm morphology will be discussed. Aspects of criticism on the strict criteria definition and use of the criteria for sperm morphology evaluation will be discussed as well as possible reasons for the decline in normal sperm morphology values and how we can compromise for this phenomenon resulting in the very low normal reference value as published in the 2010 WHO manual for the Examination and Processing of Human Semen. One of the possible solutions may be to give more attention to a limited number of abnormal sperm morphology categories and the inclusion of sperm morphology patterns. It is concluded in this review that if done correctly and with care and with strict application of existing guidelines as outlined in the 2010 WHO manual, sperm morphology measurement still has a very important role to play in the clinical evaluation of male fertility potential.

关键词： human sperm morphology male fertility potential strict criteria traditional or liberal criteria WHO manual for semen analysis

Design with Ultra Strong Polyethylene Fibers

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Materials Sciences and Applications 2011年第5期2卷 319-330页

作者： roelof Marissen 不详

Ultra strong polyethylene fibers can be made by gel-spinning of Ultra High Molecular Weight Polyethylene (UHMWPE). Such fibers exhibit extraordinary properties. They show very high tensile strength and stiffness and low density. On the other hand, the axial and transverse compression strength is low. This is a large difference with other advanced fibers like glass and carbon fibers. Additionally, the fibers are chemically inert and the bonding strength to other materials like resins is weak. Moreover, the coefficient of friction is very low, so the fiber is extremely slippery. Another property is viscoelasticity;the fiber elongates due to creep at higher loads or temperatures. This exceptional combination of properties explains why gel-spun UHMWPE fibers are not always applied in straight forward ways, e.g. like glass and carbon fibers in composites. On the other hand, weaknesses like the limited compression strength are related to very damage tolerant behavior on a micro scale. This opened application areas like providing of cut resistance. This paper describes some established applications and shows the relationship between the properties and the applications. Furthermore, some emerging applications are discussed and it is demonstrated how weaknesses can be turned into advantages.

关键词： Tensile Compression Friction Creep Density Impact

Olivine Weathering against Climate Change

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Natural Science 2017年第1期9卷 21-26页

作者： roelof Dirk Schuiling Faculty of Geosciences Utrecht University Utrecht Netherlands

One natural process has since the origin of the Earth removed almost all the CO2 that was ever produced by volcanism. That process is the reaction of CO2 and water with rocks, a process known as weathering. It is a logical choice to see if we can use the same process to remove also the vastly higher CO2 emissions caused by burning in a few hundred years the fossil fuels that have taken hundreds of millions of years for their formation. Many people claim that the rate of weathering of olivine is too slow to counter climate change, but they base this on experimental data in sterile laboratories, under exclusion of biotic and other environmental factors. As many conditions determine the weathering rate at each specific location, these laboratory conditions are irrelevant for the real world. Weathering models based on these laboratory data are off by orders of magnitude. Weathering experiments that use conditions closer to nature [1] show already much higher weathering rates. In this note I provide some data on the weathering of olivine in nature, which make clear that the weathering of olivine is fast enough to play an important role in the cycle of CO2 capture and its safe and sustainable storage as carbonate rocks. The CO2 released by volcanism has always been captured by the weathering of rocks since the origin of the Earth. Without this mechanism the Earth would be a lifeless planet with a CO2 atmosphere in the order of 100 bar, as our neighbor planet Venus demonstrates.

关键词： Climatic Change Olivine Rate of Weathering Biotic Effects

Climate Change and CO<sub>2</sub>Removal from the Atmosphere

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Natural Science 2014年第9期6卷 659-663页

作者： roelof Dirk Schuiling Institute of Geosciences Utrecht University Utrecht The Netherlands

Several methods have been proposed in recent years to counteract climate change and ocean acidification by removing CO2 from the atmosphere (Carbon Dioxide Removal). The most versatile and widely applicable of these methods is enhanced weathering of olivine, which is capable of removing billions of tons of CO2 from the atmosphere at moderate cost compared to the high cost of Carbon Capture and Storage (CCS). Despite its disadvantages, CCS is still the favored solution of many governments. Many misunderstandings of the potential of enhanced weathering persist. This paper addresses some of these misunderstandings, mainly caused by models which ignore established facts.

关键词： Mineral Carbonation Olivine Concept Failing Models

Troodos: A Giant Serpentinite Diapir

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International Journal of Geosciences 2011年第2期2卷 98-101页

作者： roelof Dirk Schuiling Institute of Geosciences

Troodos is a classical ophiolite complex. It is proposed that the serpentinized harzburgites that now form the top of the mountain and represent the originally lowest part of the ophiolite sequence rose as a diapir. This diapiric rise is caused by the pervasive serpentinization of a suboceanic harzburgite, due to rock-sea water interaction. The serpentinization caused a 44% expansion of the rocks. Contrary to salt diapirism, the driving force for this diapiric rise is not so much the difference in density, but the volume increase asscociated with the transformation of harzburgite into serpentinite. The overlying gabbros, sheeted dike complex and pillow lavas were pierced by this serpentinite diapir but barely deformed. Their interaction with sea water was li- mited to some pyroxenes in the gabbros being transformed to amphiboles, and epidotisation of some of the dikes in the sheeted dike complex. The location of steep faults in the Troodos massif is determined by the contrasting expansion behavior of different rock-types on both sides of the fault.

关键词： Ophiolites Seawater Interaction Serpentinization (Lack of) Deformation Cyprus Olympic Flame

Design Considerations on a Flexible Membrane Tsunami Flood Barrier

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Materials Sciences and Applications 2013年第12期4卷 846-855页

作者： roelof Marissen Julio Suarez Mulder Dietrich Wienke Otto Bergsma Delft University of Technology Faculty of Aerospace Engineering Delft The Netherlands Delft University of Technology Faculty of Aerospace Engineering Delft The Netherlands DSM Dyneema Urmond The Netherlands DSM Dyneema Urmond The Netherlands

Temporary high water floods may cause considerable damage. Protection against such flooding may be achieved with high dikes or walls. However, such rigid permanent structures may spoil the local architectures and views and may be quite expensive. Temporary collapsible structures do not have such disadvantages. This paper proposes such a temporary structure, consisting of a strong membrane made out of strong UHMWPE fibers (Dyneema?), a floating body and mooring cables. A two dimensional calculation scheme is presented and the calculation results are used for design considerations regarding the approximation of optimal configurations.

关键词： Flood Protection: Stress Pressure Fibers Buoyancy Floater Membrane Thickness

Nurses Opinions Regarding Delirium Care in the Older General Hospital Population and in Older Cardiac Surgery Patients Specifically: A Multicentre Survey among Dutch Nurses

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International Journal of Clinical Medicine 2014年第21期5卷 1352-1364页

作者： roelof Ettema Dianne van Harten Jita Hoogerduijn Tjitze Hoekstra Marieke Schuurmans Nursing and Paramedical Care for People with Chronic Illnesses Faculty of Health Care University of Applied Science Utrecht Utrecht The Netherlands Julius Center for Health Sciences and Primary Care University Medical Center Utrecht Utrecht The Netherlands Department of Surgery and Orthopedics R&oumlpcke Zweers Hospital Hardenberg The Netherlands Heart and Lung Department St. Antonius Hospital Nieuwegein The Netherlands

Background: Delirium is a high prevalent postoperative complication in older cardiac surgery patients and can have drastic consequence for the patient. Preventive interventions, diagnosis and treatment of delirium require specialized knowledge and skills. Objective: To gain insight in the current opinion and beliefs of nurses in hospitals concerning prevention, diagnosis and treatment of delirium in older hospital patients in general and specifically in older cardiac surgery patients. Methods: In a cross-sectional study from February to July 2010, we distributed a survey on beliefs on delirium care among 368 nurses in three hospitals in the Netherlands, in one hospital in all wards with older patients and in two hospitals in the cardiac surgery wards only. Results: Although in literature incidence rates up to 54.9% in cardiac surgery patients in hospitals are reported, with a response rate of 68% (250), half of the nurses believe that the incidence of delirium is not even 10%. Two thirds think that delirium in patients is preventable. Although, the Delirium Observation Scale is most often used for screening delirium, nearly all nurses do not routinely screen patients for delirium. Opinions on delirium of nurses working in cardiac surgery wards did not differ from nurses caring for older patients in other hospital wards. Conclusions: Nurses do have knowledge on delirium care, but there is a gap between the reported incidence in literature and the estimation of the occurrence of delirium by nurses. A two-way causal relationship emerges: because nurses underestimate the occurrence, they do not screen patients on a routine basis. And because they do not screen patients on a routine basis they underestimate the incidence.

关键词： Frailty Older People General Hospital Cardiac Surgery Delirium

Discovering Mathematics with Maple: An interactive exploration for mathematicians, engineers and econometricians 1

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