Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Modeling of eating style and its effect on intake
    Boer, J.H.W. van den; Mars, M. - \ 2015
    Appetite 86 (2015). - ISSN 0195-6663 - p. 25 - 30.
    food-intake - social facilitation - behavior - humans - perception - duration - power - size
    Observational research has indicated that modeling of eating style might occur when eating in the presence of an eating companion. This experiment investigated the effect of bite frequency of a same-sex eating companion on bite frequency, meal size and meal duration. A total of 30 normal weight young adults (m/f¿=¿8/22, age: 21.2¿±¿1.9¿years, BMI: 21.2¿±¿1.6¿kg/m2) had three ad libitum meals together with a same-sex confederate (i.e. instructed eating companion). Confederates were instructed to eat at a slow (3¿bites/min), medium (5¿bites/min) or fast (7¿bites/min) bite frequency in randomized order. Eating style was assessed through video registration and weighing left-overs. It was found that the participants' bite frequency was similar during all three conditions, i.e. slow: 3.9¿±¿1.3, medium: 4.0¿±¿1.1, fast: 4.0¿±¿1.3¿bites/min (p¿=¿0.75), as was average bite size (11¿±¿2.6¿g). Time eaten of the participants was shorter in the medium (14.9¿±¿3.6¿min) and fast condition (14.4¿±¿3.7¿min) compared to the slow condition (16.8¿±¿4.8¿min) (post hoc in both cases p¿
    Korte verblijftijd haalbaar bij mestvergisting
    Timmerman, M. ; Eekert, M. ; Riel, J.W. van; Schuman, E. - \ 2013
    V-focus 10 (2013)6. - ISSN 1574-1575 - p. 42 - 43.
    veehouderij - mestvergisting - biogas - gasproductie - fermentatie - duur - glycerol - biobased economy - warmtekrachtkoppeling - livestock farming - manure fermentation - biogas - gas production - fermentation - duration - glycerol - biobased economy - cogeneration
    Vergisting van mest bij verblijftijden van korter dan 15 dagen is haalbaar, maar mestsoort en mestkwaliteit blijken een groot effect te hebben op de biogasproductie bij deze korte verblijftijden. Het is mogelijk om bij deze korte verblijftijd een kleine hoeveelheid (<5%) glycerine toe te voegen waardoor de biogasproductie sterk toeneemt, zodat er een 2 tot 3 keer zo grote WKK kan worden neergezet als bij pure mestvergisting. Maar de biogasproductie van de glycerine hangt wel af van de mestkwaliteit.
    Restricting access time at pasture and time of grazing allocation for Holstein dairy cows: Ingestive behaviour, dry matter intake and milk production
    Mattiauda, D.A. ; Tamminga, S. ; Gibb, M.J. ; Soca, P. ; Bentancur, O. ; Chilibroste, P. - \ 2013
    Livestock Science 152 (2013)1. - ISSN 1871-1413 - p. 53 - 62.
    herbage intake - intake rates - ruminants - cattle - sward - supplementation - fermentation - digestion - regrowth - duration
    The objective of this study was to assess the effects of restricting access time to pasture and time of grazing allocation on grazing behaviour, daily dry matter intake (DMI), rumen fermentation, milk production and composition in dairy cows. Twenty-one autumn-calving Holstein cows were assigned to one of the following 3 treatments: providing access to a daily strip of pasture for either 8 h between 07:00 and 15:00 h (T7–15), 4 h between 07:00 and 11:00 h (T7–11), or 4 h between 11:00 and 15:00 h (T11–15). The experimental period consisted of 3 weeks of adaptation and 6 weeks of measurements. Cows were offered a daily herbage allowance of 18 kg DM/cow to ground level, 6.1 kg DM/day of a ground sorghum grain-based supplement and 5.2 kg DM/day of maize silage. Milk yield was greater for cows with 8 h access time to the pasture (25.4 vs. 24.1 for 8 and 4 h access time, respectively). Milk yield was not different between cows that access early (T7–11) or late (T11–15) to the grazing session. Milk protein yield was greater for cows with 8 h access time (0.75 kg/d) vs. 4 h access time treatments (0.72 kg/d). Cows with late access time to grazing in the morning produce more protein (0.74 kg/d) than cows with early access to the pasture (0.70 kg/d). Duration of access had a significant effect on herbage DMI (8.3 vs. 6.6 kg/d, for 8 and 4 h access, respectively), but there was no significant effect of time of grazing allocation. Intakes of concentrate and maize silage DM did not differ between treatments. Pasture depletion rate was significantly slower when cows had access to the pasture for 8 h compared with 4 h (0.04 vs. 0.09 cm/h), but was not affected by allocation time in the 4-h treatments. Cows grazed for significantly longer in treatment T7–11 than T11–15, achieved significantly more biting and non-biting grazing jaw movements. However, because herbage DMI did not differ between treatments T7–11 and T11–15, it appears that cows grazed more efficiency on treatment T11–15. The present study showed that reducing the period of access to pasture from 8 to 4 h decreases DMI and milk production. Cows that started their 4-h grazing session later in the morning (T11–15) produced more protein than cows that started earlier (T7–11), probably as a consequence of a larger bite mass and a tendency for higher intake rate. Rumen pH of cows grazing on treatment T11–15 declined faster than in cows on T7–11, which is in accordance with the higher VFA and ammonia rumen concentrations observed after the grazing session started.
    The effect of reduced loading density on pig welfare during long distance transport
    Gerritzen, M.A. ; Hindle, V.A. ; Steinkamp, K. ; Reimert, H.G.M. ; Werf, J.T.N. van der; Marahrens, M.A. - \ 2013
    Animal 7 (2013)11. - ISSN 1751-7311 - p. 1849 - 1857.
    slaughter pigs - ventilation - parameters - duration - behavior
    Transport of animals is a stressful procedure often resulting in significant losses for the slaughter plant. This study aimed to determine whether or not pigs would benefit from a loading density (low density (LD)) (179 kg/m2) below the normal EU standard loading density (normal density (ND)) (235 kg/m2). Eight similar, 550-km-long road journeys, were followed in which fattening pigs were transported across Germany from farm to slaughter plant. During each journey all pigs were transported at LD (n=4) or ND (n=4). Twelve female pigs per journey (total n=96) were randomly selected for measurement and monitoring of body temperature, behaviour, heart rate and blood parameters. Throughout the journeys, LD pigs displayed more resting behaviour than ND pigs. Average body temperature was lower (P
    Probabilistic analysis of hydrological drought characteristics using meteorological drought
    Wong, G. ; Lanen, H.A.J. van; Torfs, P.J.J.F. - \ 2013
    Hydrological Sciences Journal 58 (2013)2. - ISSN 0262-6667 - p. 253 - 270.
    frequency-analysis - streamflow droughts - severity - copulas - duration - europe - river - propagation - groundwater - risk
    Droughts are an inevitable consequence of climate variability and are pervasive across many regions. Their effects can vary on an extensive scale, depending on the type of drought and people’s vulnerability. Crucial characteristics of both hydrological (groundwater, streamflow) and meteorological (precipitation) droughts are related to their durations and severities, and these characteristics are typically correlated. While many studies have addressed the dependencies between these characteristics for either the meteorological or hydrological drought, the cross-dependence between meteorological and hydrological drought characteristics is barely investigated. The development of meteorological drought characteristics to hydrological drought characteristics is often hard to model and their connection is not definitively established. In order to better understand and explain this relationship, this study seeks to apply statistical tools and models. Drought characteristics data from areas in Europe with different climates are analysed. Two approaches of identifying related meteorological and hydrological drought are explored and compared. Classical linear correlation techniques do not provide promising results, indicating that any statistic of a hydrological drought is not a straightforward function of a preceding meteorological drought. Subsequently, the application of the concept of copulas to explore this dependence between meteorological and hydrological drought characteristics is investigated. The more comprehensive approach of copulas shows that the meteorological drought contains probability information of the successive hydrological drought.
    Nieuw belichtingsmodel geeft een meer evenwichtige plantbelasting (interview met Arie de Gelder)
    Bouwman-van Velden, P. ; Gelder, A. de - \ 2012
    Onder Glas 9 (2012)5. - p. 59 - 59.
    glastuinbouw - glasgroenten - belichting - duur - modellen - plantenontwikkeling - gebruikswaarde - groenten - greenhouse horticulture - greenhouse vegetables - illumination - duration - models - plant development - use value - vegetables
    Afgelopen winter is bij het onderzoek met LED en SON-T belichting in tomaten ook gekeken naar wisselende belichtingsduur. Wageningen UR glastuinbouw ontwikkelde een belichtingsmodel dat eerder werd ingezet bij de gerbera. Het lijkt er op dat de plantbelasting rond de kortste dag beter is te sturen.
    Assessing the welfare impact of foot disorders in dairy cattle by a modeling approach
    Bruijnis, M.R.N. ; Beerda, B. ; Hogeveen, H. ; Stassen, E.N. - \ 2012
    Animal 6 (2012)6. - ISSN 1751-7311 - p. 962 - 970.
    animal-welfare - holstein cows - digital dermatitis - lameness - locomotion - prevalence - lesions - pain - associations - duration
    Foot disorders are the main cause of dairy cow lameness and are considered to have a major impact on the welfare of dairy cattle. This study adopts a modeling approach, using a dynamic stochastic model, to provide more insight into the welfare impact of different types of foot disorders, both clinical and subclinical. The impact of specific foot disorders on welfare was assessed by simulating the incidence and duration of foot disorders and the pain associated with them. Pain assessment was based on locomotion scores, with underlying knowledge obtained from scientific literature and experts. The results demonstrated the seriousness of the welfare impact of foot disorders. The negative welfare impact was measured on a scale from 0 to 60, where the maximum outcome represents a cow having very severe pain during the whole year. On average, each cow achieves a welfare impact score of 12, which is 20% of the maximum welfare impact score. This welfare score equals having severe pain for a period of 3 months, indicating a serious impact on welfare. On average, digital dermatitis impacts most on welfare, which is caused by a high incidence of the painful clinical stage, followed by sole hemorrhages (SoH) and interdigital dermatitis and heel horn erosion (IDHE). The combination of a high incidence and long duration of SoH and IDHE causes this relatively high welfare impact of foot disorders that occur mostly subclinically. On average, over 1 year, 46% of the welfare impact due to foot disorders is caused by clinical foot disorders. The fact that subclinical foot disorders contribute more or less equally to the effects on welfare as clinical ones, indicates that farmers may readily underestimate the welfare impact by a factor two. Modeling welfare impact at cow level, individual cases of foot disorders, stresses the importance of pain intensity, indicating the importance of clinical foot disorders. This study demonstrated the serious welfare impact of foot disorders in dairy cattle and pointed out the considerable impact of subclinical foot disorders. Furthermore, the approach of welfare assessment, for example herd v. cow level, influenced the ranking of foot disorders for their impact on animal welfare. Potentially, this leads to different prioritization of specific solution strategies for dairy farmers, for example, focusing on cow comfort, hygiene or preventive medical treatments, foot trimming and/or health monitoring. The findings in this study support in raising awareness about this welfare issue.
    Extreme value modeling of areal rainfall from weather radar
    Overeem, A. ; Buishand, T.A. ; Holleman, I. ; Uijlenhoet, R. - \ 2010
    Water Resources Research 46 (2010). - ISSN 0043-1397
    neerslag - frequentieverdeling - duur - meteorologische waarnemingen - radar - precipitation - frequency distribution - duration - meteorological observations - radar - precipitation annual maxima - frequency estimation - reduction factors - intervals - curves - sites
    An 11 year high-quality radar rainfall data set is used to abstract annual maximum rainfall depths for durations of 15 min to 24 h and area sizes of 6 to 1.7 × 103 km2 for the Netherlands. Generalized extreme value (GEV) distributions are fitted to the annual maxima. A new method is presented to describe the distribution of extreme areal rainfall depths by modeling GEV parameters as a function of both duration and area size. This leads to a semiempirical expression from which quantiles of extreme rainfall depths can be obtained for a chosen duration, area size, and return period. The uncertainties in these quantiles are calculated using the bootstrap method. Radar-based areal reduction factors (ARFs) are derived. These ARFs are comparable to those based on high-density rain gauge networks derived from the literature. It is concluded that radar data, after careful quality control, are suitable to estimate extreme areal rainfall depths
    A quantitative approach to characterize sink-source relationships during grain filling in contrasting wheat genotypes
    Yin, X. ; Guo, W. ; Spiertz, J.H.J. - \ 2009
    Field Crops Research 114 (2009)1. - ISSN 0378-4290 - p. 119 - 126.
    high-temperature - spring wheat - durum-wheat - yield - nitrogen - growth - number - cultivars - duration - stress
    We present a simple generic framework to quantify source–sink relationships during grain filling, by using a determinate growth function which has a unique property, namely being able of explicitly describing the time for the end of a growth process. This model framework was applied to analyze these relationships in plants of six wheat (Triticum aestivum L.) genotypes grown in pots in climate-controlled greenhouses under two temperature regimes (day/night: 20/15 and 25/20 °C). The function accurately described the sigmoid pattern of grain growth (sink activity), as its modified form did for the reversed sigmoid shape of flag-leaf area (source capacity), during grain filling. The six genotypes differed significantly in grain number as well as in grain yield, ranging from 54 to 81 grains and from 2.67 to 4.52 g DM per culm, respectively, when grown at 20/15 °C. Biomass and grain yield were significantly reduced by a rise of 5 °C. Grain nitrogen contents raised from 2.1 to 2.6% as a consequence of less carbon accumulation resulting in lower grain weights at the high temperature. On average, a rise of 5 °C in temperature reduced the duration of grain growth by 12 days (>30%), and increased the growth rate from 1.32 to 1.67 mg grain-1 d-1 (20%). Genotypic differences in grain-filling duration were also larger than in rate of grain growth. The genetic variation in the flag-leaf area duration (a proxy for the capacity for intercepting radiation and photosynthesis) was positively associated with sink size. Model analysis showed that whether or not the timing for the cessation of grain filling and for the end of post-anthesis source activity was synchronized depended on temperature. The quantitative approach yielded parameters that characterize genotypic differences of post-anthesis source and sink capacity in responding to environmental variables
    Chicken lines selected for their primary antibody response to sheep red blood cells show differential hypothalamic-pituitary-adrenal axis responsiveness to mild stressors
    Adriaansen-Tennekes, R. ; Decuypere, E. ; Parmentier, H.K. ; Savelkoul, H.F.J. - \ 2009
    Poultry Science 88 (2009)9. - ISSN 0032-5791 - p. 1879 - 1882.
    individual variation - laying hens - corticosterone concentration - immune-responses - serum - resistance - duration
    The interaction between the neuroendocrine system and the immune system is well established and supports their mutually affecting relationship. Many animal selection lines have been created according to individual behavioral or neuroendocrine responses to stress. Here we present 2 chicken lines selected for 25 generations for their primary antibody response to immunization with SRBC, as well as the control line from the same parental strain. In the first experiment, the blood-sampling procedure caused a mild stress response, with the expected increase in plasma corticosterone levels. In a second experiment, group housing caused the expected increase in corticosterone levels. In both experiments, the hens of the low line showed the greatest increase in corticosterone levels to our 2 mild stressors. Our results show that birds selected throughout 25 generations for an immune parameter show different HPA axis responsiveness
    Malnutrition and mealtime ambiance in nursing homes
    Nijs, K.A.N.D. ; Graaf, C. de; Staveren, W.A. van; Groot, C.P.G.M. de - \ 2009
    Journal of the American Medical Directors Association 10 (2009)4. - ISSN 1525-8610 - p. 226 - 229.
    quality-of-life - food-intake - social facilitation - residents - weight - duration - choice - care
    Inadequate nutritional intake is the predominant cause of malnutrition in older persons. It is one of the most common and devastating conditions in nursing home residents. It is multifactorial and treatment or nutrition care plans should try to address the main causes. Such plans often include means to stimulate appetite to prevent or treat anorexia. One important stimulus, which can be modulated easily, is the meal ambiance. This article deals with the theory or mechanism behind this meal ambiance stimulus, discusses some study results, and makes practical recommendations.
    Invulling lichteisen EU-welzijnsrichtlijn voor vleeskuikens, vier lichtschema's vergeleken = Comparison of four light schedules according to EU directive 2007/43 for broilers
    Harn, J. van - \ 2009
    Lelystad : Animal Sciences Group, Wageningen UR (Rapport / Animal Sciences Group 172) - 45
    pluimveehouderij - kuikens - vleesproductie - huisvesting van kippen - verlichting - lichtsterkte - duur - dierenwelzijn - vleeskuikens - poultry farming - chicks - meat production - chicken housing - lighting - light intensity - duration - animal welfare - broilers
    Four different light schedules according to EC Directive 2007/43 for broilers were compared. This study was done with five different broilers strains
    Probabilistic forecasts of the onset of the North Australian wet season
    Lo, F. ; Wheeler, M.C. ; Meinke, H.B. ; Donald, A. - \ 2007
    Monthly Weather Review 135 (2007)10. - ISSN 0027-0644 - p. 3506 - 3520.
    rainfall - variability - prediction - duration - quality - systems - darwin
    The amount and timing of early wet-season rainfall are important for the management of many agricultural industries in north Australia. With this in mind, a wet-season onset date is defined based on the accumulation of rainfall to a predefined threshold, starting from 1 September, for each square of a 1° gridded analysis of daily rainfall across the region. Consistent with earlier studies, the interannual variability of the onset dates is shown to be well related to the immediately preceding July¿August Southern Oscillation index (SOI). Based on this relationship, a forecast method using logistic regression is developed to predict the probability that onset will occur later than the climatological mean date. This method is expanded to also predict the probabilities that onset will be later than any of a range of threshold dates around the climatological mean. When assessed using cross-validated hindcasts, the skill of the predictions exceeds that of climatological forecasts in the majority of locations in north Australia, especially in the Top End region, Cape York, and central Queensland. At times of strong anomalies in the July¿August SOI, the forecasts are reliably emphatic. Furthermore, predictions using tropical Pacific sea surface temperatures (SSTs) as the predictor are also tested. While short-lead (July¿August predictor) forecasts are more skillful using the SOI, long-lead (May¿June predictor) forecasts are more skillful using Pacific SSTs, indicative of the longer-term memory present in the ocean.
    The acute effect of bull presence on plasma profiles of luteinizing hormone in postpartum, anoestrous dairy cows
    Roelofs, J.B. ; Soede, N.M. ; Dieleman, S.J. ; Voskamp-Harkema, W. ; Kemp, B. - \ 2007
    Theriogenology 68 (2007)6. - ISSN 0093-691X - p. 902 - 907.
    suckled beef-cows - mature bulls - estrus - interval - ovarian - lh - progesterone - resumption - ovulation - duration
    The objective of this study was to investigate whether bull exposure affects LH profiles in postpartum, anoestrous dairy cows. Eight cows between 10 and 17 days after parturition were used. On Day 1, blood samples were taken at 10 min intervals for 8 h. On Day 2, blood sampling continued at 10 min intervals and after 2 h a bull was introduced behind a fence, and blood sampling continued for another 8 h. Time of resumption of luteal activity was between 25 and more than 80 days after parturition for these animals and was not related (P > 0.1) with frequency of LH pulses, amplitude of pulses and basal LH concentration on either Day 1 or Day 2. In 6 of the 8 cows, average and basal LH concentration were greater (P <0.001) during the 8 h of bull presence (0.56 ± 0.33 and 0.39 ± 0.26 ng/ml, respectively) compared to the 8 h without a bull (0.50 ± 0.30 and 0.35 ± 0.24 ng/ml, respectively). Pulse amplitude did not differ (P = 0.85) between Day 2 (0.45 ± 0.24 ng/ml) or Day 1 (0.45 ± 0.14 ng/ml). LH pulse frequency was greater (P <0.1) on Day 2 (5.3 pulses/8 h) compared to the Day 1 (4.6 pulses/8 h). In conclusion, fenceline bull exposure early postpartum seems to have an acute effect on LH-release in anoestrous dairy cows. Whether sustained bull exposure can hasten first ovulation after calving through an effect on LH release in dairy cows is an interesting area of research.
    Investment patterns in Dutch glasshouse horticulture
    Goncharova, N. - \ 2007
    Wageningen University. Promotor(en): Arie Oskam. - [S.l.] : S.n. - ISBN 9789085046684 - 180
    investering - besluitvorming - onzekerheid - tuinbouw - kassen - nederland - akkerbouw- en tuinbouwbedrijven - tuinbouwbedrijven - duur - bedrijfsbeëindiging in de landbouw - econometrische modellen - investment - decision making - uncertainty - horticulture - greenhouses - netherlands - crop enterprises - market gardens - duration - farm closures - econometric models

    Keywords: investment, uncertainty, investment spikes, entry, exit, duration model, GMM dynamic panel data estimator, Negative Binomial model, Heckman selection model, moving window ARIMA, Principal Component analysis, horticulture

    This thesis focuses on the analysis of investment decision-making in order to better understand the variables that influence a firm's profit-maximizing strategy. The goal of a firm is to continue to exist, which can be achieved through the maximization of profit. Thus, the investment decision is considered as a realization of the firm's profit-maximizing objective.

    To understand the investment decision, investments in fixed capital in Dutch glasshouse horticulture were studied. Because an investment decision is dynamic by nature, investment patterns were analysed during the period 1975-1999, thereby providing a longer term overview. The salient characteristic of Dutch glasshouse horticulture firms is that they remain small-scale family firms with respect to labour and land, but are highly capital-intensive. Moreover, in recent decades, the sector has experienced many transformations in the fields of evolution and adaptation to new technologies, consumer preferences, and market and environmental requirements. This makes the Dutch glasshouse horticulture sector an attractive case for studying investment patterns. This is done by considering an investment decision as having three components: decisions about participation, about level, and about time. These components are a tangible part of investment decision-making; they reflect the latent factors of: investment thresholds, adjustment costs, irreversibility, and risk and uncertainty, all of which predetermine investments.

    Results from this research show the relevance of separating the participation and level decisions since the set of significant variables differ (e.g. energy- and land prices are not significant for the level decision), and some of the variables exhibited contrasting signs (e.g. debts, revenue, labour cost). The impact of thresholds is tested on different types of entry and exit, which are considered as investment or disinvestment decisions. The raising of a threshold discourages firms from action; they prefer to delay any decision that can be related to the irreversibility of an investment. The results of this study do not provide strong support for the Real Option theory, which postulates that the effect of the uncertainty can be observed through the changes in investment threshold. While the model based onMarshalliantrigger points, which suggests the direct impact of the sector-characterizing variables (such as expectation of output prices, interest rate and uncertainty), explains the participation investment decision better.

    A phenomenon that has not been studied in any depth is the effect of uncertainty on investment, which is considered in many studies as ambiguous. This study argues that risk and uncertainty should be distinguished from each other. The estimation leads to the conclusion concerning the difference in their effects on the level of investment, which sometimes contrast with each other. Moreover, the asymmetry in the effect of uncertainty is confirmed.

    The timing of investment addresses the phenomenon of lumpy and intermittent patterns of investment, as estimated by a duration model. The timing of investments can be explained by the irreversibility of investment, with the lumpiness suggesting the fixed component in adjustment costs. A 6-year investment cycle was revealed at firm level and confirmed at average level. This implies that new policy instruments for increasing the adoption of new technologies will not necessarily lead to an immediate increase in investments, but will depend on, amongst others, factors associated with the degree of vintage of the installed technologies.
    Contribution of dew to the water budget of a grassland area in the Netherlands
    Jacobs, A.F.G. ; Heusinkveld, B.G. ; Wichink Kruit, R.J. ; Berkowicz, S.M. - \ 2006
    Water Resources Research 42 (2006). - ISSN 0043-1397 - 8 p.
    surface-energy balance - eddy-correlation - negev desert - heat-flux - moisture - soil - fog - ecosystem - duration - systems
    The annual amount of dew input to the water budget in the midlatitudes is mostly neglected, possibly because direct dew measurements are very difficult and time-consuming. As the Netherlands has a very high frequency of dew events, a grassland area was selected to determine whether dew input could be significant. The study site is situated within the Wageningen University meteorological station. Dew measurement experiments were carried out in 2004. Data were used to verify a surface energy dew model, which was then applied to an 11-year data set. A mean annual dew amount of 37 mm was obtained with a standard deviation of 8 mm, while the mean annual precipitation was 830 mm with a standard deviation of 200 mm. Dew contributed about 4.5% of the mean annual precipitation. The average number of dew nights per year was 250 (70%) with a standard deviation of 25 nights. This frequency significantly affects leaf wetness and possible vegetation diseases.
    A dynamic model of commutes
    Rouwendal, J. ; Vlist, A.J. van der - \ 2005
    Environment and Planning A 37 (2005)12. - ISSN 0308-518X - p. 2209 - 2232.
    search - duration - jobs - distances - mobility
    This paper studies the interaction between commuting, job mobility, and housing mobility. Many conventional models assume that the employment location has priority over the residential location and that the latter is adapted to the former. This implies that commutes which start with a job change will often be short lived because of a change in residential location that soon follows. It is also often supposed that the change in residential location is made with the intention to avoid long commutes. In this paper we test the empirical validity of these hypotheses. Our data are a sample of Dutch workers who report changes on the housing and labor market between 1990 and 1998. It appears from these data that both job mobility and housing mobility are often followed by repeat mobility on the same market, but also on the other market. Job mobility indeed triggers residential mobility, but the effect of residential mobility on job changes is of comparable magnitude. Moreover, both types of mobility lead to substantial repeat mobility. We specify duration models that focus on the time during which employment ¿ housing arrangements (hence, commutes) remain unchanged. Estimation results for these models confirm that commutes which start with housing mobility and those which start with job mobility have similar characteristics with respect to induced future mobility. We are unable to find evidence supporting the hypothesis that long commutes resulting from a job change induce additional residential mobility. Another result of the analysis is that workers belonging to dual-earner households are more mobile on both markets than other workers
    Comparison times are longer for hedonic than for intensity judgements of taste stimuli
    Veldhuizen, M.G. ; Vessaz, M.N. ; Kroeze, J.H.A. - \ 2005
    Physiology and Behavior 84 (2005)3. - ISSN 0031-9384 - p. 489 - 495.
    gustatory reaction-time - orbitofrontal cortex - human adults - responses - duration - monkey - preference - capacity - neurons - humans
    Response times of intensity and hedonic comparisons were determined in a within-subjects experimental design. Forced-choice paired comparisons of orange lemonades with various concentrations of added quinine sulfate were made by 48 subjects. Depending on experimental condition, the subjects had to focus either on intensity or on pleasantness and give their responses as fast as possible. The data showed shorter response times for intensity comparisons than for pleasantness comparisons. Although taste processing may be partially serial and partially parallel, the larger part of the response times and the differences between them may be due to cognitive processing
    Spatial heternogeneity and the persistence of infectious diseases
    Hagenaars, T.H.J. ; Donelly, C.A. ; Ferguson, N.M. - \ 2004
    Journal of Theoretical Biology 229 (2004)3. - ISSN 0022-5193 - p. 349 - 359.
    stochastic epidemics - extinction times - community size - endemic period - metapopulation - dynamics - measles - models - transmission - duration
    The endemic persistence of infectious diseases can often not be understood without taking into account the relevant heterogeneities of host mixing. Here, we consider spatial heterogeneity, defined as `patchiness¿ of the host population. After briefly reviewing how disease persistence is influenced by population size, reproduction number and infectious period, we explore its dependence on the level of spatial heterogeneity. Analysis and simulation of disease transmission in a symmetric meta-population suggest that disease persistence typically becomes worse as spatial heterogeneity increases, although local persistence optima can occur for infections with oscillatory population dynamics. We obtain insight into the dynamics that underlie the observed persistence patterns by studying the infection prevalence correlation between patches and by comparing full-model simulations to results obtained using simplified patch-level descriptions of the interplay between local extinctions and between-patch transmissions. The observed patterns are interpreted in terms of rescue effects for strong spatial heterogeneity and in terms of between-patch coherence and synchronization effects at intermediate and weak levels of heterogeneity.
    Service Encounters as a Sequence of Events: The Importance of Peak Experiences
    Antonides, G. ; Verhoef, P.C. ; Hoog, A.N. de - \ 2004
    Journal of Service Research 7 (2004)1. - ISSN 1094-6705 - p. 53 - 64.
    retrospective evaluations - satisfaction - choice - regression - duration - model - time
    A service encounter can be considered as a sequence of events. In the early service literature, it was assumed that firms should deliver a consistent performance during a service encounter However research in psychology states that this is not necessarily true. In addition to the average performance, the peaks in the performance are important. Likewise, some service researchers have stressed the importance of a happy ending. The authors test a model on how events contribute to the overall evaluation of a sequence of events. They show that the average performance during the encounter is important. However their results also stress the importance of peak experiences for satisfaction formation. Thus, managers of service encounters should not only manage the overall performance of a service encounter To further elevate satisfaction, they could also provide some positive peak experiences.
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