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  • All of the experiments were

    2018-10-29

    All of the experiments were carried out under similar environmental conditions. The clean room in which the experiments were performed was maintained at 37°C. Table 4 represents the atmospheric conditions maintained within the laboratory across all experiments undertaken. During each dripping done, the column of blood in the syringe was maintained at 2.5cc with no air bubbles. In order to compare the drip stains formed, all stains were recorded on the same representative non-absorbent/non-porous, smooth paper target surface. Table 5 provides the specification of the target surface that scd1 has been used for the experiments. Blood is an integral component in the experiments undertaken. Blood from healthy pigs was used in dataset creation. Table 6 provides a summary of the properties of porcine blood that was used in the experiments. Only singular, non-overlapping, regular drip stains were included in the dataset. The samples created during the experiment were allowed to dry and hence photographed using a Nikon Coolpix L610 camera. The images were taken by placing horizontal and vertical scales with respect to the stain [6]. The camera lens was held parallel to the target surface on which the stains were formed [6]. The aspect ratio for each image was maintained. Fig. 2 represents how length, breadth, angle of impact and total number of spines were calculated for each stain pattern.
    Technical validation Each sample was carefully created. For each particular angle of impact at which the stains were created, the angle of impact was calculated from the static stains using the accepted formula, sin−1(breadth/length) [6]. To validate and also to minimize experimental error the following steps were undertaken. The standard deviation and standard error values for the measured parameters, such as length, breadth, total number of spines and calculated angle of impact for the 108 datapoints strong dataset was calculated. The standard error and variance of the samples created with Heparin was estimated. The paper on ‘2D Source area prediction based on physical characteristics of a regular, passive blood drip stain’ reports the length, breadth of stain created using fresh blood and Warfarin were found to follow normal distribution while the length and breadth of stains created with Heparin were found to follow a non-normal distribution [7]. Again, the distribution of the total number of spines for the stains created with Heparin, Warfarin and fresh blood was found to deviate from a normal distribution [7]. The length, breadth and total number of spines of the dataset of Heparin for dosage of 260I.U. mixed with 250ml of porcine blood consisting of 9 datapoints can be represented as a normal distribution by using the inverse of the square root of length value, inverse of the square of the breadth and logarithm of the total number of spines as a variable (refer Fig. 3) [8]. The transformed length, breadth and total number of spines for the nine datapoints were found to follow normal distribution with Shapiro Wilk value of 0.862(p=0.100>0.05), 0.909(p=0.310>0.05) and 0.901 (p=0.334>0.05) [df=7, as the number of spines for two of nine datapoints was recorded as zero] respectively. Blood drops were ejected from a 2.5cc subcutaneous syringe with needle filled to capacity with 250ml of porcine blood thoroughly admixed with 260I.U. of Heparin. The points that include 95% of the inverse of the square root of length observations are 0.9164 (mean)±1.96×0.25953(standard deviation), giving a range of 0.4077212 and 1.4250788 [9]. There stands only 5% chance that the population mean will lie outside the points defined by 0.9164±2.306×0.08651 (standard error) [tα/2,df= 2.306 (df=8)] [9], giving a range of 0.7169 and 1.1159. Similarly, only 5% of the inverse of the square of the breadth observations are expected to lie outside the range 2.4698±1.96×2.11568, defined by the points, −1.67693 and 6.61653. There is 95% chance that the mean of the breadth value of the population will lie in the range defined by the points 2.4698±2.306×0.70523, giving the range values of 0.84354 and 4.09606. The points that include 95% of the logarithm value of the total number of spines are 1.3157(mean)±1.96×1.17956(standard deviation), giving a lower limit value of −0.99624 and upper limit value of 3.62764. There exist only 0.05 probability that the mean of the population of the logarithmic value of the total number of spines will lie outside the range defined by the points 1.3157(mean)±2.306×0.44583 [Lower bound: 0.28762; Upper bound: 2.343784].