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Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Climate change, scenarios and their impact on potato diseases
No full textSince 1970 s Europe has warmed rapidly, more than observed globally. The warming may partially result from inherent variation of climate but its rate and geographical distribution fits the expected pattern of global climate change. The observed rate of warming is comparable to the expected rate in the next decades. Over the 21st century climate is expected to become gradually milder and more humid in Northern Europe and hotter and more arid in the South; Central Europe is becoming warmer with more extreme weather events; CO2 concentration continues to rise steadily. Global climate scenarios suggest that warming until mid-century is already largely determined and only after mid-century the outcome of climate change could be significantly affected by policy decisions and economic development. In some areas in Europe the warming in the past 30 years is so large that trends of seasonal temperature parameters are discernible. If statistics on pest occurrence or multiplication rate exist in these areas, it may be possible to attribute statistically part or all of the changes in pest dynamics to the observed climatic changes. Regional climate scenarios extend knowledge of the climate to future decades and provide daily weather data for modelling pest dynamics in future conditions. Repeating model runs over years gives an estimate of a probability distribution of pest risk. If pest risk is cumulative over years or shows lag after a climate threshold has been crossed, each of individual runs requires special consideration in setting initial values or climate data over several years. It is possible to generate hourly weather data for any particular site and period in future, which allows simulation of future local epidemics. However, these data represent only one possible set of climate conditions and it is difficult to explore the entire range of climate conditions. Another way of representing climate is to compute the combined distribution of climate parameters e.g. number of rain days, daily minimum temperature, and daily temperature range in future by extrapolating statistically from past climate data or from the daily output of regional climate models. If observed pest response to climate can be related to these parameters, the model can be used for deriving estimates of change of pest risk as climate changes. All predictions of future pest risk are conditional to the assumption that pest response to climate and interactions with host, soil, and surrounding environment are stable. Knowing that this assumption cannot always be true it seems useless to extend pest risk predictions beyond a few decades. Yet, over a few decades climatic variation can be larger than the general warming trend in any particular region. This makes it difficult to reach results that would be valuable for potato industry and supporting research. The value of studying the effect of climate change on potato pests lies in detecting ongoing changes of pest risks and understanding their origin, which is useful for planning pest control under the current climate.vokMyynti MTT Tietopalvelut 31600 Jokioine
Impact of global warming on potato late blight: risk, yield loss and control
No full textIlmaston lämpenemisen vaikutusta perunaruton aiheuttamaan satotappioon ja ruton torjuntatarpeeseen tutkittiin rakentamalla malli ruttoepidemian ajoittamiseen ja malli perunan kasvusta ruton rajoittamana. Perunan istutus- ja taimettumisaika ennustetaan tehoisan lämpösumman kertymisellä ja ruttoepidemian alkamisaika tehoisan lämpösumman kertymisellä sadepäivinä. Kasvumallin parametrit arvioitiin perunan kasvun mittauksista, jotka tehtiin normaalissa ja kohotetussa (+3 °C) lämpötilassa 1993-1995. Perunan ennustetaan taimettuvan, kun yli 0 °C laskettu lämpösumma saavuttaa 631 astepäivää. Lämpösumman laskeminen aloitetaan keväällä 16 vrk:n keskilämpötilan noustessa yli 0 °C. Ruttoepidemian ennustetaan alkavan, kun taimettumisesta alkaen laskettu sadepäivien (sade ÿ 0,1 mm) lämpösumma saavuttaa 156 astepäivää. Lämpösumman päivittäinen kertymä ruton ennustamisessa on korkeintaan 10 °C. Jokioisten säähavaintoja käyttäen tehtiin alustava herkkyyskoe 1-3 °C suuruisen lämpötilan nousun vaikutuksesta ruttoon ja perunan kasvuun. Aika, jolloin peruna täytyy suojata rutolta fungisidiruiskutuksella, pitenee 10-20 päivää l °C lämpenemistä kohti. Ilmaston lämpenemisen aiheuttama satotappioitten kasvu rutolta suojaamattomissa kasvustoissa on samaa suuruusluokkaa kuin satopotentiaalin kasvu: noin 2 t/ha kuiva-ainetta l °C lämpenemistä kohti.The impact of climate warming on yield losses caused by potato late blight and on the need for disease control was studied by constructing models for timing late blight epidemics and a model of potato growth constrained by late blight. Empirical models predicting the date of planting and emergence of potato were based on thermal time, and a model predicting the date of late blight outbreak was based on thermal time on rainy days. Experiments were conducted over 3 years under ambient and elevated (+3°C) temperatures to obtain parameter values for the growth model. Potato emergence is predicted to occur at 631 degree days accumulated above 0°C after the 16-day running mean temperature in spring exceeds 0°C. A blight outbreak is predicted to occur when the effective temperature sum accumulated above 8°C after potato emergence, on days with at least 0.1 mm of precipitation, achieves 156 degree days. In the prediction of the outbreak the maximum daily accumulation of temperature is limited to 10 degree days. A preliminary sensitivity study carried out at one site in southern Finland suggests that over a range of 1 to 3°C warming, the period during which late blight needs to be controlled by fungicide applications would be 10-20 days longer per 1°C of warming. The increase in yield loss of unprotected crops would be of the same magnitude as the increase in yield potential, around 2 t/ha of dry matter per 1°C of warming.vokIlmaston lämpenemisen vaikutus perunaruttoo
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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