Surveying Persons with Disabilities: A Source Guide (Version 1)

As a collaborator with the Cornell Rehabilitation Research and Training Center on Disability Demographics and Statistics, Mathematica Policy Research, Inc. has been working on a project that identifies the strengths and limitations in existing disability data collection in both content and data collection methodology. The intended outcomes of this project include expanding and synthesizing knowledge of best practices and the extent existing data use those practices, informing the development of data enhancement options, and contributing to a more informed use of existing data. In an effort to provide the public with an up-to-date and easily accessible source of research on the methodological issues associated with surveying persons with disabilities, MPR has prepared a Source Guide of material related to this topic. The Source Guide contains 150 abstracts, summaries, and references, followed by a Subject Index, which cross references the sources from the Reference List under various subjects. The Source Guide is viewed as a “living document,” and will be periodically updated

Optimal binning of X-ray spectra and response matrix design

A theoretical framework is developed to estimate the optimal binning of X-ray spectra. We derived expressions for the optimal bin size for model spectra as well as for observed data using different levels of sophistication. It is shown that by taking into account both the number of photons in a given spectral model bin and their average energy over the bin size, the number of model energy bins and the size of the response matrix can be reduced by a factor of $10-100$. The response matrix should then contain the response at the bin centre as well as its derivative with respect to the incoming photon energy. We provide practical guidelines for how to construct optimal energy grids as well as how to structure the response matrix. A few examples are presented to illustrate the present methods.Comment: 16 pages, 7 figures, accepted for publication in Astronomy and Astrophysic

Perspectives of Anaerobic Soil Disinfestation

Biological soil disinfestation is an environmentally friendly method to disinfest soil. From now on we refer to it as anaerobic soil disinfestation (ASD). With ASD a green manure crop (40 t/ha) is homogeneously incorporated into the topsoil (0-30 cm) after which the field is lightly compacted and irrigated. Subsequently the field is mechanically covered with air tight virtually impermeable film (VIF) to restrict oxygen supply to the topsoil. The soil is left covered for six weeks in the summer. In this period anaerobic conditions develop rapidly in which toxic fermentation products are formed. These conditions are responsible for elimination of fungal and bacterial pathogens as well as parasitic nematodes, insects and weeds. In the Netherlands since 2004 anaerobic soil disinfestation (ASD) was applied on approximately 70 ha mainly for asparagus and strawberry runners production. When the asparagus crop was replanted ASD proved to be profitable for many years by controlling Fusarium oxysporum. Although highly effective against soilborne pathogens and pests ASD is not applied widely in the Netherlands due to the high costs of about € 4000 per ha. Apart from the costs this technique needs special attention to prevent plastic damage. Moreover the mechanism behind ASD is not well defined which makes recommendations for growers complex. A new and promising development in ASD is the application of defined products on a basis of mixtures of carbon hydrates and proteins. The mechanism of ASD will be studied in the next few years with some of these products by measuring gases and fatty acids and microbial shifts in relation to efficacy. Chemical soil disinfestation with fumigants is restricted more and more and a non-chemical approach of soil disinfestation like ASD is urgently neede

Inzet RTK-GPS in de teelt van een gewas : met RTK-GPS schoffelen in cichorei na zaaien met RTK-GPS

In juni 2008 werd op het proefbedrijf van PPO in Lelystad onderzoek gedaan naar de invloed van RTK-GPS stuursystemen op de rechtgeleiding van een werktuig. Met RTK-GPS (RTK staat voor Real Time Kinetic) kan op centimeters nauwkeurig gereden worden. De vraag die beantwoord moest worden was: is de afwijking die de fabrikant aangeeft haalbaar

Schoffel Robrocrop ruimt onkruid in de rij op

De in de plantrij werkende schoffel van Franse Sarl Radis probeert in Nederland al enkele jaren vaste voet aan de grond te krijgen. Dat dat tot op heden niet lukt, komt vooral door de beperkte werksnelheid van de machine. De heen en weer gaande beweging van de schoffelelementen om het onkruid in de gewasrij weg te hakken kost relatief veel tijd. Dat drukt de capaciteit. De Robocrop-schoffel, vorige week op de open dagen van zaadbedrijf Bejo in Warmenhuizen, heeft roterende schoffelelementen. Spiraalvormige bewegingen makend, beweegt elk hakmes steeds in de rij en vervolgens erbuiten. Daarmee is een rijsnelheid mogelijk van twee planten per seconde. Bij een afstand in de rij van 50 centimeter is dat 3,6 kilometer per uur. De werkdiepte is 2 centimeter. Een camera bekijkt het gewas voor de schoffel in een vlak van 2 vierkante meter. De software stelt vast waar de planten exact staan, en past op basis daarvan de rotatiesnelheid van elk schoffelmes aan. Staan de planten dichter op elkaar dan de bedoeling, dan draait het schoffelmes sneller, zo de verblijftijd in de rij verkortend. Omgekeerd draait het schoffelmes evenredig langzamer. De afstand in de rij mag maximaal 30 procent afwijken van de ingestelde afstand, aldus Garford. De machine houdt ook rekening met een instelbare `vrije zone¿ rond elke plant, om te voorkomen dat de (pers)pot of breed uitgroeiend blad door het schoffelmes wordt geraakt. Stuurschijven houden het apparaat automatisch op koers. De cameratechniek en software is volgens Garford gelijk aan die op de zelfsturende schoffels van Steketee/Ecodan. De schoffelaandrijving gaat met hydromotoren. Voor een vierrijer volstaat een olieopbrengst van 30 liter bij 150 bar. Een vierrijer kost 5.500 euro (met 1 camera), een negenrijer, (met 3 camera¿s) komt op 9.500 euro

Adaptive radiotherapy for preoperative gastric cancer

Preoperative radiotherapy for gastric cancer is a novel treatment approach, aiming to precisely irradiate the target while sparing the surrounding healthy tissue to limit potential adverse side effects. However, the stomach's inherent motion and deformation, as well as its proximity to vital organs, pose challenges for precise irradiation. A promising solution is adaptive radiotherapy, which adjusts the treatment plan to match daily anatomical variations. One such approach is a Library of Plans (LoP), where multiple treatment plans covering various anatomical variations are created, and the most suitable plan is selected daily. This thesis explored a CBCT-guided adaptive strategy for preoperative gastric cancer radiotherapy. The observed substantial stomach motion and deformation highlights the need for an adaptive strategy. The feasibility of a CBCT-guided LoP was demonstrated through observer evaluations, showing that a range of observers can consistently select the most appropriate treatment plan. Furthermore, using a gastric deformation model, stomach shape was predicted from stomach volumes. A dosimetric comparison between the LoP and a single-plan approach showed that the LoP reduces the average irradiated volume and the dose to organs at risk while maintaining equal target coverage. Hence, this research underscores the benefit of an adaptive strategy for preoperative gastric cancer radiotherapy and contributes to understanding the challenges and potential solutions in this field