Qstr Modeling For Qualitative And Quantitative Toxicity Prediction Of Diverse Chemical Pesticides In Honey Bee For Regulatory Purpose

2668 words - 11 pages

2.3 Selection of modeling approach for QSTR model development
Since, the experimental toxicity data considered here exhibited complex nonlinearities, it was appropriate to select nonlinear modeling approach for establishing the QSTR models for predicting the toxicities of pesticides in HB. Accordingly, we selected the nonlinear PNN and GRNN modeling approaches for development of QSTR models for qualitative (toxicity classes) and quantitative (endpoint toxicity values) prediction of toxicities of structurally diverse chemical pesticides in honey bee using a set of simple molecular descriptors. PNN and GRNN approaches have successfully been applied in computational toxicology earlier (Singh ...view middle of the document...

The node computes the distance d(s,x) from the test vector x to the training samples and output the value of the kernel function. The outcome of each of the layer one cell is added separately for the different classes by the connections to the output cells with weight one.
Figure 2a
2.3.2 GRNN-QSTR model
GRNN uses nonlinear Gaussian kernel regression and estimates any arbitrary function between the input and output vectors, drawing the function estimate directly from the training data and provide the optimal estimation of continuous variables implementing the statistical concepts of conditional probability (Du et al., 2008). It is a four-layered NN (Fig. 2b) consisting of an input layer, a pattern layer, a summation layer, and an output layer, and does not require any iterative training procedure to converge to the desired solution. The input layer provides input vector x to pattern layer, which consists of neurons for each training datum or for each cluster center. In this layer, the weighted squared Euclidean distance is calculated according to; D_i^2= (x-x^i )^(T ) (x-x^i), where xi refers to ith training vector. Any new input applied to network is first subtracted from pattern layer neuron values, then according to the distance function either squares or absolute values of subtracts are summed and applied to activation function. Results are transferred to summation layer. Neurons in summation layer add dot product of pattern layer outputs and weights. At output layer, multiplication of pattern layer outputs and training data output Y values (Yf(x)K) are divided by weighted outputs of the pattern layer (f(x)K) to estimate desired Y, the conditional mean of Y given x, as (Specht, 1991);
Y(x)= (∫_(-∞)^∞▒Yf(x,Y)dY)/(∫_(-∞)^∞▒f(x,Y)dY) (2)
where K is a constant associated with Parzen window and f (x,Y) represents the known joint continuous probability density function (PDF) of a vector random variable, x, and a scalar random variable, Y. Since, the density, f (x,Y) is not known and it is usually estimated from a sample of observations of x and Y, the probability estimator f(x,Y) is based on a sample value xi and Yi of the random variables x and Y, as;.
f ̂(x,Y)= 1/(〖n(2π)〗^█(((p-1))/2@ ) σ^((p+1)) ) ∑_(i=1)^n▒exp⁡〖[-((x-x^i )^(T ) (x-x^i))/〖2σ〗^2 〗 ] (3)
where n is the number of sample observations, p is the dimension of the vector variable x, σ is the smoothing parameter. The probability estimate, f(x,Y) assigns a sample probability of width σ for each sample xi and Yi, and the probability estimate is the sum of these sample probabilities. Now, supplementing the joint probability evaluation in Eq (3) into the conditional mean Eq (2) yields,
Y(x)= (∑_(j=1)^p▒〖y_j exp[(-D_j)/〖2σ〗^2 ] 〗)/(∑_(j=1)^p▒exp[(-D_j)/〖2σ〗^2 ] ) (4)
Here, Eq. (4) presents the exponentially weighted sum of each training pattern according to the smoothing parameter, σ and its Euclidean distance to the unknown pattern x. It is...

Find Another Essay On QSTR modeling for qualitative and quantitative toxicity prediction of diverse chemical pesticides in honey bee for regulatory purpose

Agricultural and Ecological Role of the Honey Bee

2264 words - 10 pages Honey bee foragers perform waggle dances to inform other foragers in the hive about the location, presence, and the odor of beneficial food sources and new hive sites. The aim of the study in review was to investigate how the characteristics of waggle dances for natural food sources and environmental factors affect dance follower behavior. Due to the assumption that food source profitability tends to decrease with increasing foraging distance, a

Characteristics of Qualitative and Quantitative Methods

937 words - 4 pages Qualitative and quantitative researcher’s exhibited conflicting ways of approaching a research. Some researchers prefer qualitative over quantitative and vice-versa. Also, it is common for qualitative and quantitative to be used together in a research. But, both methods when carried out correctly provide good research. Plus, both methods have their own unique differences and characteristics. In this paper I will define three of these

The Meaning of Quantitative and Qualitative Research

1227 words - 5 pages are different than the normal results. Researchers don’t use them in quantitative research because they are too complicated to account for and then put them in the research. The data is based off of the results falling into the normal category. Qualitative research’s main focus is to grasp an individual’s lived experiences, through their emotions, mental processes and behavior (Guts, 2014). Qualitative research studies subjective human

Bolivian History and Culture This report was assigned for the purpose of learning about Bolivia's complex history and diverse culture

1492 words - 6 pages (Weil, 135).The culture of Bolivia is very diverse and complex. The various social classes each have their own beliefs and values resulting in little or no understanding or respect for each other. The predominantly Indian population has its own distinction of culture among the thirty-six different sects. There is very little common ground to bridge the difference between the aristocratic whites of Spanish decent and the indigenous, subsistence

Quantitative and Qualitative methods

983 words - 4 pages mainly focuses on gathering this data and generalising it across groups of people. Qualitative Methods 3.1 Qualitative methods are used in collecting data which are used with describing meaning unlike quantitative data which is used for statistical data like charts etc. like I have mentioned this is done by using case studies interviews questionnaires these are a bigger more in depth research to produce for example you would not use this if you

Qualitative and Quantitative Research

1648 words - 7 pages Introduction This essay aims to cover two main focus points. The first section of this essay will take an in depth look at the major differences between two research methods – Qualitative and Quantitative. I will explore when and why they are used for specific types of research and how they apply to some types of work more effectively. The second area for this essay will be based around the research question- what factors contribute to you

Research Qualitative and Quantitative

1231 words - 5 pages conclusion has becomes more effective, leading to stronger possibilities for the community.Qualitative and Quantitative ResearchQualitative research is when, "concepts are viewed as sensitizing ideas or terms that enhance our understanding" (Hagan,2006). When the researcher is researching to understand the why in a subject, qualitative research is most adequate due to the processes used in qualitative research. The research could begin with in

Quantitative and Qualitative Methods

1119 words - 4 pages (b) Data Collection Mixed methods research was conducted, where both qualitative and quantitative research were conducted. Such a method is beneficial as both methods can complement each other and fill the gaps that may be present if only one method had been used, thus allowing for a better grasp of the situation present. Despite its advantages, concerns have been raised about the possible dilution of research effort as resources have to be

Qualitative Tests for Carbonyls: Aldehydes vs. Ketones. Various chemical tests identifying ketones and aldehydes are used in this experiment in order to identify an unknown carbonyl compound.

1040 words - 4 pages orange to blue-green.The Schiff's Test is a chemical test for the detection of aldehydes. When the sample is added to the decolorized Schiff reagent in the presence of an aldehyde, a bright purple color develops. Ketones do not react.The last test, called the Iodoform Test, identifies the presence of a methyl ketone functional group via a halogenations reaction. A yellow precipitate tells us we have a methyl ketone.2Materials and Hazards3 Name MW

quantitative and qualitative research approach

1217 words - 5 pages been used as research approach recently. (What is the purpose of this para??)(Combine with the first para?) As Fred Kerlinger (1999) has mentioned about quantitative research, “There's no such thing as qualitative data. Everything is either 1 or 0”, quantitative research approach is an approach which researchers using scientific method such as questionnaires and experiment to collect numeric data to analysis their research statistically. It has

Advantages And Disadvantages Of Qualitative Research And Briefly Quantitative Research

1169 words - 5 pages within the clinical practice area; and discuss whether the results are beneficial to the nursing profession. The implications for care delivery will be addressed and finally a conclusion will be given which will include recommendations for future practice through research.There are two forms of research methods and these are qualitative and quantitative; there are many advantages and disadvantages for using them to gather information; yet depending on

Similar Essays

Qstr Modeling For Qualitative And Quantitative Toxicity Prediction Of Diverse Chemical Pesticides In Honey Bee For Regulatory Purpose

2506 words - 11 pages %), geometrical (74.57 %) and topological (45.61 % - 65.12%). A wide variability in molecular properties of the considered pesticides reveals the importance of the selected descriptors for proposed QSTR modeling studies. 3.1 Qualitative QSTR modeling A qualitative QSTR model was constructed to categorize the pesticides among toxic and non-toxic (two-categories) as well as among highly toxic, moderate toxic, slightly toxic, and non-toxic (four

Qsar Modeling For Predicting Aquatic Toxicity Of Chemicals

3908 words - 16 pages different time durations. Moreover, most of these studies considered complex descriptors and in several of these, prediction accuracies were not satisfactory, thus limiting the applicability of these models for acute toxicity prediction purpose. The EL-based QSAR modeling approaches in the present study considering the large dataset of structurally diverse chemicals yielded the best prediction accuracy in complete data of different test species of

Differences In Qualitative And Quantitative Research Methods For Business

662 words - 3 pages There are two different methods for collecting data. There is Qualitative Research and Quantitative Research. Let's come up with some ideas on how to perform each method and brainstorm on different tools we can use. We will need to be aware of the pros and cons attached to each method as well. To get the conversation started here are my ideas and suggestions.First, I wanted to point out the differences in these methods. Qualitative research is

Statement Of Purpose For Chemical Engineering

826 words - 3 pages have been challenging subjects for the past two years and all of which have given me skills and influenced me in my decision to pursue a degree in chemical engineering. After attending open days at several university campuses many phrases such as hard work and determination had summarised the qualities that are needed to study chemical engineering, all of which are attributes that I have gained from the years A-level subjects. During my time