Putting the Phytophthora infestans genome sequence at work: multiple novel avirulence and potato resistance gene candidates revealed

Individual variation in milk yield response to concentrate intake and milking interval length During the last century in the Netherlands milk production per cow has almost tripled. Accordingly, the amount of concentrates yearly fed per cow strongly increased. Furthermore, automation and robotisation has changed dairy management, especially by the introduction of automatic concentrate feeders and milking systems. A new management concept, emerging in the last decades, is Precision Livestock Farming (PLF). The objective of PLF is to optimize livestock production, by on-line monitoring and control of the production process, utilizing the technical possibilities of automation and robotisation. Nowadays, individual settings for daily concentrate supply and milking frequency are based on standards, ignoring individual variation in milk yield response on concentrate intake and milking frequency. This leads to the main hypothesis for this thesis research that profitability of dairy farming can be improved by utilizing information on individual variation in response. The first objective of this research was to quantify the individual variation in milk yield response to concentrate intake and milking interval length, in order to assess the economic prospects of applying individual optimal settings for concentrate supply and milking frequency. In the first observational study (Ch. 2), data from 299 cows on four farms in the first 3 weeks of the lactation were collected. Individual response in daily milk yield to concentrate intake was analysed by a random coefficient model. During the first three weeks of lactation, considerable variation in individual milk yield response to concentrate intake was found on all four farms. An economic simulation was carried out, based on the estimated parameter values in the observational study. Individual economically optimized settings for concentrate supply were compared with conventional strategies for concentrate supply based on averaged population response parameters. Applying individual economic optimal settings for concentrate supply during early lactation, potential economic gain ranges from 0.20 to 2.03 €/cow/day. In a second observational study (Ch.3), data of normal uninterrupted milkings during one week from 311 cows kept in 5 separate herds on one farm were collected. The data set consisted of 4,915 records and random coefficient models were fitted to estimate the individual effects of milking interval on daily milk yield and milking duration. Between individuals, considerable variation in milk yield and milking duration was found in response to milking interval. Based on the estimated individual response, a simulation was carried out in order to optimize the utilization of an AMS for different herd sizes and occupation rates. Applying optimal individual milking intervals for a herd of 60 cows and an AMS operating at an occupation rate of 64%, the average milking interval reduced from 0.421 day to 0.400 day, the daily milk yield at the herd level increased from 1,883 to 1,909 kg/day, and milk revenues increased from 498 to 507 €/day. In the actual situation, the herd consisted of 60 cows. A further increase of daily milk revenues per AMS was possible by increasing the operation rate and/or herd size. The conclusion is that between dairy cows there is a considerable variation in effects of concentrate intake and milking interval length on milk yield and, consequently, milking duration. A marked increase in economic profits of dairy production is possible by improvement of the concentrate allocation and/or the utilisation of an AMS, applying optimal individual settings based on the actual individual response in milk yield. Development of adaptive models The second objective was the development and testing of adaptive models for on-line estimation of the actual individual response in milk yield to concentrate intake and milking interval length. In Ch. 4 adaptive dynamic models for on-line estimation of the actual individual milk yield response to concentrate intake and milking interval length were evaluated. The parameters in these models may change over time and are updated through a Bayesian approach for on-line analysis of time series. Time series data of daily milk yield during the first 200 days of lactation from 17 cows were analysed with different adaptive dynamic models. Three models were evaluated: a model with linear terms for concentrate intake and length of milking interval, a model with linear and quadratic terms, and an enhanced model in order to obtain more stable parameter estimates. The linear model was only useful for forecasting milk production and the estimated parameters of the quadratic model turned out to be unstable. The parsimony of the enhanced model lead to far more stable parameter estimates. In Ch. 5 an adaptive dynamic model was used for time series analysis of herd mean daily milk yield, in order to quantify the impact of heat stress and to assess the potential for monitoring and control of milk production. Time series data of daily milk yield from 2003 to 2006 were collected on six experimental research farms in The Netherlands. The impact of heat stress was quantified in terms of critical temperature, duration and loss in milk yield. The estimated critical temperature was 17.8 oC, the duration was 5.5 days, and loss in milk yield 31.4 kg milk/cow/year, averaged over farms. Besides estimation of the impact of heat stress, level and trend, including a weekly cyclical pattern were estimated to evaluate the production process. The Bayesian approach for on-line analysis of time series comprises also a procedure for the detection of potential outliers and other deteriorations that might be promising for monitoring the production process. Outliers and other process deteriorations are adequately detected by this monitoring procedure. The conclusion is that on-line estimation of the actual individual response in milk yield and milking duration is possible following a Bayesian approach for time series using an adaptive dynamic model. Besides estimation of the actual response the Bayesian approach adequately detects process deteriorations. Therefore, adaptive dynamic models provide a useful tool for control and monitoring of the dairy production process. </p

Met hagel op aardappels schieten

Op 20 juni 2011 promoveerde Hendrik Rietman aan Wageningen University (WUR) op zijn proefschrift getiteld: “Putting the Phytophthora infestans genome sequence at work; multiple novel avirulence and potato resistance gene candidates revealed”. Zijn promotor, Prof. Dr. Richard G. F. Visser, en co-promotor, Dr. Ir. Vivianne G. A. A. Vleeshouwers, zijn beiden verbonden aan de leerstoelgroep Plantenveredeling van de WUR, waar ook het onderzoek werd uitgevoerd. Tevens is er samengewerkt met de leerstoelgroep Fytopathologie (WUR), het Sainsbury Lab en het James Hutton Instituut (beiden gevestigd in het Verenigd Koninkrijk). Financiering was afkomstig van het ‘Parapluplan Phytophthora’ en WUR Plantenveredeling

Feasibility of a second iteration wrist and hand supported training system for self-administered training at home in chronic stroke

Telerehabilitation allows continued rehabilitation at home after discharge. The use of rehabilitation technology supporting wrist and hand movements within a motivational gaming environment could enable patients to train independently and ultimately serve as a way to increase the dosage of practice. This has been previously examined in the European SCRIPT project using a first prototype, showing potential feasibility, although several usability issues needed further attention. The current study examined feasibility and clinical changes of a second iteration training system, involving an updated wrist and hand supporting orthosis and larger variety of games with respect to the first iteration. Nine chronic stroke patients with impaired arm and hand function were recruited to use the training system at home for six weeks. Evaluation of feasibility and arm and hand function were assessed before and after training. Median weekly training duration was 113 minutes. Participants accepted the six weeks of training (median Intrinsic Motivation Inventory = 4.4 points and median System Usability Scale = 73%). After training, significant improvements were found for the Fugl Meyer assessment, Action Research Arm Test and self-perceived amount of arm and hand use in daily life. These findings indicate that technology-supported arm and hand training can be a promising tool for self-administered practice at home after stroke.Final Accepted Versio

The feasability of reflexive control in transfemoral prostheses

The feasibility of reflexive control in transfemoral prosthesis is assessed using a model of the lower extremity. The artificial triggering of reflexes, the processing of the central nervous system, the EMG detection and the control input to the prosthetic knee all take time. A model was used to assess what time delay is acceptable in such a closed loop system for it to be of additional value

Iterative solvers in forming process simulations

The use of iterative solvers in implicit forming process simulations is studied. The time and memory requirements are compared with direct solvers and assessed in relation with the rest of the Newton-Raphson iteration process. It is shown that conjugate gradient{like solvers with a proper preconditioning can signicantly improve the overall time performance of a forming process simulation as compared to the use of direct solvers. For the presented examples the time spent in the solver is not dominating the total solution time anymor

Design and characterization of dielectric filled TM110_{110} microwave cavities for ultrafast electron microscopy

Microwave cavities oscillating in the TM$_{110}$ mode can be used as dynamic electron-optical elements inside an electron microscope. By filling the cavity with a dielectric material it becomes more compact and power efficient, facilitating the implementation in an electron microscope. However, the incorporation of the dielectric material makes the manufacturing process more difficult. Presented here are the steps taken to characterize the dielectric material, and to reproducibly fabricate dielectric filled cavities. Also presented are two versions with improved capabilities. The first, called a dual-mode cavity, is designed to support two modes simultaneously. The second has been optimized for low power consumption. With this optimized cavity a magnetic field strength of 2.84 $\pm$ 0.07 mT was generated at an input power of 14.2 $\pm$ 0.2 W. Due to the low input powers and small dimensions, these dielectric cavities are ideal as electron-optical elements for electron microscopy setups

A mixed elastoplastic / rigid-plastic material model

A new integration algorithm is described for large strain plastic deformations. The algorithm degenerates to the Euler forward elastoplastic{plastic model for small strain increments and to the rigid{plastic model for large strain increments. The model benets from the advantages of both models: accuracy and fast convergence over a large range of strain increments

Six-month effects of early or delayed provision of an ankle-foot orthosis in patients with (sub)acute stroke:A randomized controlled trial

Objective: To study the six-month clinical effects of providing ankle-foot orthoses at different moments (early or delayed) in (sub)acute stroke; this is a follow-up to a published trial. Design: Randomized controlled trial. Setting: Rehabilitation centre. Subjects: Unilateral hemiparetic stroke subjects maximal six weeks post-stroke with indication for ankle-foot orthosis use. Interventions: Subjects were randomly assigned to early (at inclusion; week 1) or delayed provision (eight weeks later; week 9). Outcome measures: Functional tests assessing balance and mobility were performed bi-weekly for 17 weeks and at week 26. Results: In all, 33 subjects were randomized. No differences at week 26 were found between both groups for any of the outcome measures. However, results suggest that early provision leads to better outcomes in the first 11–13 weeks. Berg Balance Scale (P= 0.006), Functional Ambulation Categories (P=0.033) and 6-minute walk test (P<0.001) showed significantly different patterns over time. Clinically relevant but statistically non-significant differences of 4–10 weeks in reaching independent walking with higher balance levels were found, favouring early provision. Conclusion: No six-month differences in functional outcomes of providing ankle-foot orthoses at different moments in the early rehabilitation after stroke were found. Results suggest that there is a period of 11–13 weeks in which early provision may be beneficial, possibly resulting in early independent and safe walking. However, our study was underpowered. Further research including larger numbers of subjects is warranted