61 research outputs found
Satellite retrieved aerosol properties for battlespace characterization and sensor performance
No full textSea basing operations in coastal environments require a rapid and accurate description of the physical conditions in the region. Battlespace characterization and sensor performance assist in optimizing the efficiency and safety of operations, of which the detection of targets at low level above the sea surface is all-important. The environmental conditions of the marine boundary layer (MBL) – due to weather and atmospheric effects – change continuously in space and time, which certainly holds for the aerosol make-up. Models have been developed to describe the electrooptical propagation in the boundary layer as a function of meteorological parameters. EOSTAR is such an end-toend model suite for EO sensor performance in which the Advanced Navy Aerosol Model (ANAM) is embedded for computing the aerosol extinction. While ANAM provides favourable results in open ocean conditions, in coastal zones the model lacks accuracy due to the presence of aerosols from a variety of sources that need to be assessed. In offshore wind conditions continental aerosols of anthropogenic and natural origin mix with marine aerosols produced in the surf zone and by wave breaking further offshore. Radiometers on satellites can be used to retrieve the spatial variation over an extended area determined by the swath width, with a resolution determined by the radiometer pixel size. In this contribution we explore the potential of satellite measurements to provide information on the aerosol properties over the range of interest in order to correctly handle their influence on transmission characteristics in the coastal zone. Results from measurements of the multidisciplinary Maritime REA/Battlespace Preparation 2007 trial, held during 20 April and 5 May 2007 near the vicinity of the island Elba along the west coast of Italy, are presented in this analysis. For one particular day, the satellite retrieved aerosol optical thickness (AOT) is to be compared with hand-held sun photometer measurements for quality assessment. The AOT values are converted into aerosol extinction coefficients for a pre-defined path. For one visible wavelength channel the transmission loss is computed with these coefficients and is compared with the computed transmission loss for the path in case of a) a single extinction coefficient obtained from measurements and b) a modeled extinction coefficient obtained from ANAM
Methods for efficient drug development in neuropsychiatric diseases
No full textKlinisch onderzoek bij het ontwikkelen van nieuwe geneesmiddelen tegen neuropsychiatrische ziekten (zoals schizofrenie en depressie) is vaak niet optimaal en doorgaans moeilijk te verbeteren. Dit komt door een moeizame diagnose van ziektebeelden, die vrijwel altijd uit meerdere symptomen bestaan en waarvan de relatieve ernst lastig is te meten, zo schrijft Joep Schoemaker in zijn proefschrift, getiteld ‘Methods for efficient drug development in neuropsychiatric diseases’. De auteur, jarenlang werkzaam geweest als onderzoeksleider binnen de farmaceutische industrie, heeft in zijn proefschrift vier klinische studies opgenomen die vanuit verschillende invalshoeken waren opgezet om in een zo kort mogelijke tijd duidelijkheid te verkrijgen over de werking en verdraagbaarheid van nieuwe proefmedicijnen tegen symptomen van depressie en schizofrenie. Daarnaast heeft hij nader onderzocht waarom depressieve patiënten vaak goed reageren op een placebo (nepmiddel) en menig schizofrene patiënt vervroegd uit een studie stapt terwijl de medicatie vaak toch goed lijkt aan te slaan. Immers, wanneer veel patiënten verbeteren op placebo of vroeg wensen te stoppen met deelname aan een studie maakt dat de interpretatie van resultaten extra lastig, zo niet ondoenlijk. De rol van de patiënt De meetbaarheid van geneesmiddelwerking (en daarmee de efficiëntie van klinisch onderzoek) wordt in belangrijke mate bepaald door de mate waarin patiënten gemotiveerd zijn om aan dubbelblinde studies deel te nemen. Bijna 1500 patiënten met schizofrenie werden bereid gevonden om 12 tot 52 weken lang deel te nemen aan in het proefschrift beschreven klinische studies, waarbij hun oude medicatie kon blijven worden gebruikt of inname van het testmiddel bij succesvolle afronding van de hoofdstudie kon worden voortgezet. Twee maatregelen die voor veel patiënten aantrekkelijk zijn. Het belang van goede onderzoeksmethodes Zuivere metingen stellen vaak erg hoge eisen aan de onderzoeksopzet, die uiteindelijk in haar geheel als te kostbaar kan worden beschouwd. In het proefschrift worden twee voorbeelden gegeven van studie-bezuinigingen, die uiteindelijk kunnen leiden tot slecht interpreteerbare resultaten en de noodzaak tot kostbare herhaling van onderzoek. Zo werd verzuimd om in een Japanse studie een placebo-arm mee te nemen, waardoor de autoriteiten uiteindelijk onvoldoende waren overtuigd van de werking van het oorspronkelijk Europese antidepressivum om het tot de Japanse markt toe te laten. Een tweede voorbeeld betreft additionele metingen en analyses die meestal achterwege worden gelaten, maar het in een gerapporteerde studie mogelijk maakten om een zwakke verbetering op lage doses van het testmiddel als toevallig resultaat af te doen en verdere ontwikkeling stop te zetten. Aan de hand van uitgebreid literatuuronderzoek en post-hoc analyses konden uiteindelijk geen patiënt- of studiekarakteristieken worden aangewezen die verband houden met placebo respons in depressie of het besluit van schizofreniepatiënten om voortijdig uit een studie te stappen. Conclusies Placebo-gecontroleerd onderzoek blijft de norm voor het aantonen van de werkzaamheid van nieuwe geneesmiddelen. Bij de opzet van dubbelblinde studies dient te worden gecompenseerd voor respons op placebo en voortijdige patiënt-uitval door middel van een verhoogde steekproefgrootte. Tijdens de vroege klinische fase is het wenselijk om iedere vorm van ruis weg te nemen door middel van verscherpte meettechnieken. Grootschalige, naturalistische studies kunnen een overtuigend beeld geven van de toegevoegde waarde van een nieuw geneesmiddel. Dubbelblinde verleng-studies laten toe om de effectiviteit van een proefmedicijn op lange termijn in kaart te brengen. De bereidwilligheid van farmaceutische bedrijven om alle onderzoeksgegevens publiekelijk toegankelijk te maken kan verder bijdragen tot een verbetering van onderzoeksmethoden in neuropsychiatrische aandoeningen
Ambachtsschool Mosveld
No full textOntwerp van een ambachtsschool aan het Mosveld in Amsterdam Noord.Interiors, Buildings and CitiesArchitectureArchitectur
Flood Risk Assessment & Investment Framework: A framework for flood risk reduction strategies in the Hollandsche IJssel
No full textThe Hollandsche IJssel is a river between Rotterdam and Gouda and is protected from the main river system in the Netherlands by a storm surge barrier. The Hollandsche IJssel experiences several problems: the storm surge barrier dates from 1958 and has a relatively low closure reliability; three quarters of the dikes have been rejected according to the safety standards due to macrostabilty; subsidence of the dikes is approximately 90cm per century; there is limited space available to reinforce the dikes because of the dense housing next to the dikes. To determine the current flood probability and risk, the use of fragility curves is applied. They represent the state of the dikes and can be combined with a probability density function of water levels, which represents the state of the storm surge barrier. This will return the flood probability. By combining them with damage curves, the flood risk can be assessed. To determine cost-optimal flood risk reduction strategies, the use of equivalent annual cost is applied. The equivalent annual cost is defined as the net present value of a project devided by the present value of annuity. It can be seen as an interest weighted average annual cash flow. By keeping the equivalent annual cost as continuously as low as possible, flood risk reduction strategies can be determined which after manual post-processing proved to be cost-optimal. This proved to result in three strategies for the Hollandsche IJssel: the dike reinforcement strategy, the double barrier strategy and the canalization strategy. The dike reinforcement strategy gradually reinforces the dikes and keeps the current storm surge barrier until no longer possible after which it is replaced by a similar one (likely around 2060). The double barrier strategy suggests the construction of a second storm surge barrier to increase closure reliability. This leads to a postponement of dike reinforcements, which are still required due to subsidence. Eventually, because of the limited amount of space that is available due to the dense housing: both lead to inevitability of canalization somewhere after 2100 (with the used schematization around 2120). Because of this inevitability, the recommended strategy is the third strategy: implement canalization immediately.Hydraulic Structures & Flood RiskHydraulic EngineeringCivil Engineering and Geoscience
Genome-wide association study of anti-Müllerian hormone levels in pre-menopausal women of late reproductive age and relationship with genetic determinants of reproductive lifespan
No full textThis is the author accepted manuscript. The final version is available from Oxford University Press via the DOI in this record.Anti-Müllerian hormone (AMH) is required for sexual differentiation in the fetus, and in adult females AMH is produced by growing ovarian follicles. Consequently, AMH levels are correlated with ovarian reserve, declining towards menopause when the oocyte pool is exhausted. A previous genome-wide association study identified three genetic variants in and around the AMH gene that explained 25% of variation in AMH levels in adolescent males but did not identify any genetic associations reaching genome-wide significance in adolescent females. To explore the role of genetic variation in determining AMH levels in women of late reproductive age, we carried out a genome-wide meta-analysis in 3,344 pre-menopausal women from five cohorts (median age 44–48 years at blood draw). A single genetic variant, rs16991615, previously associated with age at menopause, reached genome-wide significance at P=3.48×10-10, with a per allele difference in age-adjusted inverse normal AMH of 0.26 SD (95% CI [0.18,0.34]). We investigated whether genetic determinants of female reproductive lifespan were more generally associated with pre-menopausal AMH levels. Genetically-predicted age at menarche had no robust association but genetically-predicted age at menopause was associated with lower AMH levels by 0.18 SD (95% CI [0.14,0.21]) in age-adjusted inverse normal AMH per one-year earlier age at menopause. Our findings provide genetic support for the well-established use of AMH as a marker of ovarian reserve.Breast Cancer NowInstitute of Cancer Researc
Trends in hydraulics laboratory research in the Netherlands
No full textScope and aims in model techniques, instrumental aids for hydraulic model studies,investigations of structures for flow control, river studies, model investigations on local scour, problems connected with flows due to differences in density, from Spaarndam to Veersche Gat, hydraulic refinement of engineering structures, wave action on structures, the collecting of field data, navigation in small-scale models, the use of digital computers in hydraulic research, developments in model investigations of coasts and harbours.Hydraulic EngineeringCivil Engineering and Geoscience
The use of equivalent annual cost for cost benefit analyses in flood risk reduction strategies
No full textIn many parts of the world, flooding is a big risk. There are numerous strategies to reduce flood risk. The amount of flood risk reduction strategies grows exponentially with the amount of possible measures that can be implemented and possible timings when measures can be implemented. In this paper, the use of a financial method called “equivalent annual cost” (EAC) is assessed to reduce that number of strategies and evaluate cost-optimal strategies. The use of EAC allows the comparison between short-term and long-term measures by expressing them into an annual interest weighted expected expenditure. As soon as a measure has to be implemented (i.e. the annual risk becomes too large or the safety standards are exceeded), the EAC for all combinations of measures is determined and the combination is implemented with the lowest EAC. This almost leads to cost-optimal flood risk reduction strategies that, by manual optimization, can be improved further. A case study has also been performed in the Hollandsche IJssel which proved the use of EAC. Here it has led to cost-optimal flood risk reduction strategies. The method is tested in one case and it is recommended to apply and test it in other cases as well.Integral Design & ManagementHydraulic Structures and Flood Ris
Meta-analyses identify 13 loci associated with age at menopause and highlight DNA repair and immune pathways
No full textTo newly identify loci for age at natural menopause, we carried out a meta-analysis of 22 genome-wide association studies (GWAS) in 38,968 women of European descent, with replication in up to 14,435 women. In addition to four known loci, we identified 13 loci newly associated with age at natural menopause (at P < 5 × 10(-8)). Candidate genes located at these newly associated loci include genes implicated in DNA repair (EXO1, HELQ, UIMC1, FAM175A, FANCI, TLK1, POLG and PRIM1) and immune function (IL11, NLRP11 and PRRC2A (also known as BAT2)). Gene-set enrichment pathway analyses using the full GWAS data set identified exoDNase, NF-κB signaling and mitochondrial dysfunction as biological processes related to timing of menopause
Accelerating MRO procedures for composite materials using innovative detection techniques
No full textThe development of large commercial aircraft such as the Airbus A350 and the Boeing 787, together with military aircraft such as the Lockheed Martin F35, with a large share of composite components of up to 50%, make it necessary for attention to be focussed on the development of new and effective maintenance strategies. In this paper, we address the development of ultrasonic measurement techniques, with a focus on structural health monitoring (SHM) techniques that are able to quickly inspect large structural parts of the aircraft. The combination of real-time SHM techniques, together with the parallel development of automated repair techniques for bonded structures, will make it possible to operate the aircraft at lower costs and for longer periods of time, thereby increasing the economic life of these aircraft structures.Aerospace Structures and MaterialsAerospace Engineerin
Segmentation and wake removal of seafaring vessels in optical satellite images
No full textThis paper aims at the segmentation of seafaring vessels in optical satellite images, which allows an accurate length estimation. In maritime situation awareness, vessel length is an important parameter to classify a vessel. The proposed segmentation system consists of robust foreground-background separation, wake detection and ship-wake separation, simultaneous position and profile clustering and a special module for small vessel segmentation. We compared our system with a baseline implementation on 53 vessels that were observed with GeoEye-1. The results show that the relative L1 error in the length estimation is reduced from 3.9 to 0.5, which is an improvement of 87%. We learned that the wake removal is an important element for the accurate segmentation and length estimation of ships
- …
