Abstract: Although the existence of higher order associations has been proved, interspecific association is generally treated as a pair-wise phenomenon. Its possible reason is that although pair-wise association is only an imperfect description of the relationships among species, its methods are simple and well known. Unfortunately, the complexity of vegetation can not be described by such simplex methods. This paper shows two methods which enable detailed analysis of higher-order associations: Juhász-Nagy’s information theory functions and the log-linear contingency table analysis. From mathematical point of view, the two methods are closely related (both methods measure the non-randomness in the multi-way contingency tables). On the other hand, their theoretical backgrounds are different. The log-linear contingency table analysis was developed by statisticians to solve general statistical problems, while Juhász-Nagy’s approach was developed by a biologist to solve biological problems. The aim of this paper is to show how these two approaches decompose the total association, to point at the similarities and differences between the two approaches, and by this way to facilitate the analysis of higher order associations.

Keywords: associatum, diversity of species combinations, pattern analysis, 3rd-order association

Abstract: An approach of building phylogenetic trees is to define a distance function based on amino acid sequences of distinct proteins. The aim of this approach is to determine a weighted tree topology that approximates the entire functional similarity relations between proteins, defined by a distance function. In this case – according to the definition - the similarity relation has a symmetric property. However, the assumption of symmetry is not always appropriate, because non-symmetric similarity relations between proteins might have a biological significance. This notion inspired us to define a novel, compressionbased, non-symmetric dissimilarity measure and to modify the ubiquitous ‘Unweighted Pair Group Method with Arithmetic Mean’ (UPGMA)-based tree-building algorithm so that the new measure can be applied.

Keywords: phylogenetic trees, non-symmetric dissimilarity measures, Unweighted Pair Group Method with Arithmetic Mean, compression–based similarity measure, hydrogenase proteins

Abstract: The Hungarian mortality rates were analyzed by autoregressive integrated moving average models and seasonal time series models examined the data of acute childhood lymphoid leukaemia. The mortality data may be analyzed by time series methods such as autoregressive integrated moving average (ARIMA) modelling. This method is demonstrated by two examples: analysis of the mortality rates of cerebrovascular diseases and analysis of the mortality rates of cancer of cervix. The relationships between time series of mortality rates were studied with ARIMA models. Calculations of confidence intervals for autoregressive parameters by tree methods: standard normal distribution as estimation and estimation of the White's theory and the continuous time case estimation. We present a new approach to analyzing the occurrence of acute childhood lymphoid leukaemia. We decompose time series into components. The periodicity of acute childhood lymphoid leukaemia in Hungary was examined using seasonal decomposition time series method. The seasonal components of the dates of diagnosis revealed that a higher percent of the peaks fell within the winter months than in the other seasons. This proves the seasonal occurrence of the childhood leukaemia in Hungary.

Keywords: time series analysis, autoregressive integrated moving average models, mortality rates, seasonal decomposition time series method, acute childhood lymphoid leukaemia

Abstract: In order to replace the rather complicated physico-chemical method, a mathematical technique related to the binding of phosphate ions was elaborated to determine the labile, and thus plant-available phosphate content of the soil. The technique is based on the analysis of the quantity of phosphate bound to the soil in the equilibrium state when soil samples are suspended in solutions containing various concentrations of phosphate. The majority of soils contain a certain amount of adsorbed phosphate, so negative adsorption is observed if the analysis is carried out with solutions containing little or no phosphate. The isotherm models generally used to describe adsorption processes do not assume the presence of any material originally bound on the adsorbent surface, so their starting point is a state with a zero quantity of adsorbed material on the adsorbent in a solution with an initial equilibrium concentration of zero. In the case of soil phosphate adsorption, however, different results are obtained, as the soil already contains adsorbed phosphate in its original state. For this reason the isotherm model was modified. The modified isotherm model was fitted to the measurement data using non-linear regression. The quantity of phosphate originally adsorbed on the soil can be calculated using a model parameter. The phosphate quantity calculated in this way exhibits a close correlation both with the isotopically exchangeable phosphate content, and with the results obtained with the best chemical extraction methods.

Keywords: soil, phosphate, adsorption, model

Abstract: A number of C3 temperate dry grassland species and winter wheat plants were grown in open top chambers either at 365 μmol mol-1 (AC) or at 700 μmol mol-1 (EC) air CO2 concentrations. Gas exchange measurements were made at several air CO2 concentrations. When measured at higher CO2 concentrations, net photosynthetic rate was higher in plants grown at EC than at AC. The widely accepted Farquhar net photosynthesis model was parameterized and tested using several observed data. After parameterization the test results corresponded satisfactorily with observed values under several environmental conditions.

Keywords: temperate grasses, winter wheat, photosynthesis, modelling

Abstract: The aim of the present work was to determine the applicability of the AFRCWHEAT2 wheat growth model under Hungarian conditions. The Farquhar model, which, when properly calibrated, gives a satisfactory description of the net photosynthesis of Hungarian winter wheat varieties at various atmospheric CO2 concentrations, temperatures and light conditions, was incorporated into the model. Both the original AFRCWHEAT2 model and the modified AF2MOD model were tested on long-term yield and climatic data series from Győr-Moson-Sopron County. It was observed that the average yield over the period 1980-1990 was well simulated by both models, but the AF2MOD simulated the annual fluctuations much better: the determination coefficients describing the correlation between the actual wheat yield in Győr-Moson-Sopron county over the whole period and the values generated using the models were r² = 0.32 for the AFRCWHEAT2 model and r² = 0.86 for AF2MOD. A comparison of the results simulated using the AFRCWHEAT2 and AF2MOD models demonstrated that detailed physiological submodels are required for the mathematical description of plant growth if yields are to be accurately estimated and the effects of environmental changes adequately described. A good example of this is the description of the effect of atmospheric CO2 concentration on simulated yield figures, which depended on the climate of the given year in the AF2MOD model, but was described by a simple linear function in the AFRCWHEAT2 model.

Keywords: winter wheat, modelling, calibration, elevated CO2 concentration

Abstract: In high-dimensional spaces classification methods could be more effective using various feature selection methods. The training procedure could be speeded up by decreasing the dimension of the feature space, and the classification method could be improved by removing noisy or irrelevant features. In this paper we present a new method which weights the features according to their importance instead of removing the negligible ones via kernel functions. It could be applied to a range of real-world problems. We tested it on several biological datasets like a small part of the UCI Learning Repository and SCOP and the Leukaemia AML-ALL databases, and obtained a significantly better classification performance than that using the usual unweighted method.

Keywords: Support Vector Machines (SVMs), classification, kernel functions, feature ranking algorithms

Abstract: There is an increased interest in the use of spatial explicit modelling techniques in ecological research. One of the strength of this technique is the possibility to explicitly study the effect of environmental heterogeneity on the dynamics of populations or whole communities. Most of these studies focused on aspects of spatial heterogeneity, and studies focusing on environmental change employed other modelling techniques. Only recently were these two aspects of heterogeneity coupled within the same framework. The paper aims to review algorithms for generating spatially and temporarily heterogeneous landscapes that can be used in studies of population dynamics. These models have the potential to give new insight into the dynamics of populations living in a fragmented and changing environment.

Keywords: Cellular automata, percolation map, heterogeneous landscape, dynamic landscape, habitat fragmentation

Abstract: Climate change affects on insect populations in many ways: it can cause a shift in geographical spread, abundance, or diversity, it can change the location, the timing and the magnitude of outbreaks of pests and it can define the phenological or even the genetic properties of the species. Long-time investigations of special insect populations, simulation models and scenario studies give us very important information about the response of the insects far away and near to our century. Getting to know the potential responses of insect populations to climate change makes us possible to evaluate the adaptation of pest management alternatives as well as to formulate our future management policy. In this paper we apply two simple models, in order to introduce a complex case study for a Sycamore lace bug population. We test how the model works in case the whether conditions are very different from those in our days. Thus, besides we can understand the processes that happen in present, we can analyze the effects of a possible climate change, as well.

Keywords: climate change, insects, pest management, simulation, agriculture

Abstract: The growth requirements of Trichoderma fungi that are wide spread saprotrophic soil microorganisms, are quite similar, therefore it is essential to define the environmental factor(s) along which they divide the available ecological niches. For this reason, we determined chemical and physical properties of 24 soil samples from different localities of Hungary, the presence of Trichoderma species and the relationships between two groups of data were analyzed with different statistical methods. The coexistence of 13 identified Trichoderma spp. proved to be a general phenomenon, which provided a good opportunity to explore the dividing environmental factors. Only redundancy analysis gave a reasonable model from 26 abiotic soil parameters. However, the number of variables was two times higher than that of species, thus the model was built in step-by-step process during which the explanation power of parameters was assessed with Monte Carlo permutation test. The best possible model of 13 soil properties explained 66.19 % of variance in the occurrence of Trichoderma species. Their positions in the triplots showed the separation of their niches along some of the investigated abiotic environmental variables. The available Zn-content had the highest explaining power however the in vitro zinc tolerance test did not justify its importance.

Keywords: Trichoderma spp., coexistence, edaphic parameters, redundancy analysis, niche separation

Abstract: Inhibitory effect of 21 commercial and 6 experimental fungicides was assessed in model experiments against pearl millet downy mildew disease. Chemicals differed strongly by their anti-mildew activity, however neither the pathogen nor the host plant showed complete tolerance to any of compounds tested. Nevertheless, the plants outgrew depressant effect of compounds observed in germling stage and this activity did not significantly influence the yield. There was a significant correlation between yield performance and disease inhibitory effects assessed either in vitro or in vivo tests. The response of pathogen to investigated compounds varied during ontogeny, where zoosporangium formation was found to be the most sensitive ontogenetic event. When comparing responses of pathogen and host with fungicides by means of principal component analysis, the presence of two independent components has been demonstrated accounting for 86% of the total variation to which responses of host and pathogen contributed differently. The antisporulant activity of compounds evaluated on detached leaf segments and their positive effect on yield significantly correlated allowing to predict the expectable grain yield significantly (p>0.05). Beside acylanilides andoprim, drazoxolon and efosit offered efficacy on the level requested. Metalaxyl and tridemorph as well as andoprim and cymoxanil acted synergistically against S. graminicola.

Keywords: ontogeny, fungicide screening, yield performance, synergy

Abstract: The statistical analysis monthly Hungarian (1967-2001) and Austrian (1989-2003) rabies and Hungarian bovine tuberculosis (1950-1979) cases were statistically analyzed. There were eradication campaigns against both diseases, which gave us the unique opportunity to observe how the statistical properties of the time series changed due to the eradication program. The fluctuations around the trend were got by removing the 12 month moving averages from the time series. In order to characterize the structure of the contacts among the individuals exposed to the diseases and the underlying processes governing the behavior of the epidemics, the fluctuations were analyzed before and after eradication separately. It turned out that the tails of the complementary cumulative distribution functions differ in the rabies cases, and do not differ in the case of tuberculosis. In each case the tail of the distribution follows an Inverse Power Law (IPL) function and describes the distribution of extreme events. It is possible to make conclusions about the dimensions of the processes from the fitted exponents. These dimensions are not related necessarily to the spatial dimensions, but to the possible connections. The knowledge about the distributions give us the opportunity to asses the risk of epidemic outbreaks.

Keywords: epidemiology, immunization, rabies, time series analysis, IPL distribution

Abstract: Colour vision is a physiological phenomenon, and rays are not coloured (Newton, Wright). While counting hues of solar spectrum is a solved problem, the exact number of colours is unknown. Existing colour systems do not provide automatically colour census methods. This work addressed only to the 24 bit RGB-colour system. This complete colour space itself is countable. Discovering principles for ordering colours is a prerequisite of any efficient census algorithm. Colours (r, g, b) we define, as a partition of total n = r + g + b amount of intensity into 3 parts also with r/g and g/b ratios fixed. Partition spectra are the lexicographically sorted list of these partitions. Such and also geometrically defined sub-domains of RGB-cube can be transformed into 1D colour spectra by reshuffling according to their HSV-hue-angles in order to bring similar colours into close neighbourhood. These we call pseudo-solar colour spectra. Our estimation for subjectively discriminated RGB-colours is no more than 202583.

Keywords: partition-colour-spectra, RGB-cube, HSV-space, ordering colours , reshuffling by hues

Abstract: This paper focuses on regression with binomial response data. In these cases logit regression is the most used model. An example is a retrospective biomedical problem, where multicollinearity occurs, thus the variances of the estimated parameters are large. In this paper we propose to apply the ridge method to the maximum likelihood estimation of the logit model parameters. The efficiency of the proposed technique was investigated using a biomedical data set. A random sampling technique was used to study the effect of sample size on the ML and the logistic ML estimation.

Keywords: logit, multicollinearity, bootstrap, restless legs

Abstract: An agro-ecosystem is directed by the interactions among the populations living in it and depending on many abiotic factors. It is needed to investigate as many factors as possible. People are also interested in the effects of predicted climate change, experienced climate variability and frequently present extremal weather conditions nowadays. Elements of the system have direct and indirect influence on each other. Indirect or hidden types of interactions can not be expressed as different kinds of material flow. It would be also nice to combine the optimalisation of the proficiency and environmental protection together with the forecast risk, damages and profit. When extending the already existing models, they become more complex and immense, so simulation and monitoring are not enough for examining and describing the whole interaction process. Application of graph theory - using well known graph theory theorems and having the help of computers - is especially powerful for controlling huge systems that are difficult to survey by other existing methods. Using informatics and electronics agricultural production can be controlled through a complex system, which integrates biological, technological and economical factors.

Keywords: agriculture, climate, ecosystem, food web, graph, model

Abstract: Some phenomenons are modelled most naturally by two probabilities, because use of a single combined measure would result in an undesirable loss of information. E.g. diagnostic tests are obligatorily characterized by their sensitivity and specificity, risk of disease is often reported for two subpopulations e.g. males and females rather than for the whole population, etc. Here we present a statistical test and a related method to construct simultaneous two-dimensional confidence sets for two probabilities estimated from independent samples. We also describe a computer algorithm for these calculations.

Keywords: diagnostic test, confidence, statistics

Abstract: In our days attention has been focused on the analysis of the effects of electromagnetic fields both in human and veterinary medicine. The significance of analyses has been underlined by both therapeutic and noxions effects of magnetic field therapies to the living organism. Due to the fact that modern technical devices are widely used, the phenomena and data observed in connection with their use urge exact evaluation and analysis. The exact effect mechanism of electromagnetic field therapies is not quite clear. The oxygen uptake of cells is supposedly increased by the induced magnetic field [18]. Electromagnetic field therapies in human and veterinary medicine are primarily used for treating soft tissue lesions [8], and bone and joint disorders [9]. There are some new investigations trying to explain the effects of the treatments for positive and negative stress sensibility. In the first part of our study the therapeutic and noxious effects observed in human and veterinary biology are summarised without aiming at completeness. In the second part the effect of magnetic field therapy in horses is thoroughly examined. The local effects of electromagnetic field treatments as well as the biological effects of electromagnetic therapy using magnetic blanket on blood gas and biochemical parameters are tested. Paired t-test was applied in the course of biometric evaluations. The description of blood gas and acid-base parameters may it possible to apply magnetic field therapies for healing purpose as well as prevent stress-related diseases in race horses. The results of our investigation might lead to the conclusion that they are adaptable in human medicine as well.

Keywords: magnetic protection of the environment magnetic field therapy, electrosmog, blood gas parameters, paired t-test, error of first kind