LVQ and HOG based speed limit traffic signs detection and categorization

This conference paper was presented in the International Conference on Informatics, Electronics and Vision, ICIEV 2014; Dhaka; Bangladesh; 23 May 2014 through 24 May 2014 [© 2014 IEEE] The conference paper's definite version is available at: http://dx.doi.org/10.1109/ICIEV.2014.6850741The proper identification of the traffic signs can ensure driving safety and can play a very important role in reducing the number of road accidents significantly. This paper represents a uniform way to detect the speed limit traffic signs and to confirm it by recognizing the sign's speed number. In this system, firstly the red color objects are segmented from an image using LVQ. Secondly, detected circular part is extracted from the color segmented image using bounding box and then Histogram Oriented Gradient (HOG) is used to collect the feature of the extracted part of circular object and finally SVM classifier is applied to train the HOG features of each speed no. into their corresponding classes. In general, the system detects the prohibitory traffic sign in the first place, specifies whether the detected sign is a speed limit sign, and then determines the allowed speed in case the detected sign is a speed limit sign. The SVM classifier was trained with 200 images which were collected in different light conditions. To check the robustness of this system, it was tested against 381 images which contain 361 Speed Limit traffic sign and 30 Non- Speed Limit signs. It was found that the accuracy of recognition was 92.75% which indicates clearly the high robustness targeted by this system.Publishe

Sorting of LPXTG Peptides by Archetypal Sortase A: Role of Invariant Substrate Residues in Modulating the Enzyme Dynamics and Conformational Signature of a Productive Substrate

Transpeptidase sortase catalyzes the covalent anchoring of surface proteins to the cell wall in Gram-positive bacteria. Sortase A (SrtA) of <i>Staphylococcus aureus</i> is a prototype enzyme and considered a bona fide drug target because several substrate proteins are virulence-related and implicated in pathogenesis. Besides, SrtA also works as a versatile tool in protein engineering. Surface proteins destined for cell wall anchoring contain a LPXTG sequence located in their C-terminus which serves as a substrate recognition motif for SrtA. Recent studies have implicated substrate-induced conformational dynamics in SrtA. In the present work, we have explored the roles of invariant Leu and Pro residues of the substrate in modulating the enzyme dynamics with a view to understand the selection process of a catalytically competent substrate. Overall results of molecular dynamics simulations and experiments carried out with noncanonical substrates and site-directed mutagenesis reveal that the kinked conformation due to Pro in LPXTG is obligatory for productive binding but does not per se control the enzyme dynamics. The Leu residue of the substrate appears to play the crucial role of an anchor to the beta6–beta7 loop directing the conformational transition of the enzyme from an “open” to a “closed” state subsequent to which the Pro residue facilitates the consummation of binding through predominant engagement of the loop and catalytic motif residues in hydrophobic interactions. Collectively, our study provides insights about specificity, tolerance, and conformational sorting of substrate by SrtA. These results have important implications in designing newer substrates and inhibitors for this multifaceted enzyme

Crystallization and preliminary X-ray diffraction studies of sortase A from Streptococcus pneumoniae

Sortases are cell-membrane-anchored cysteine transpeptidases that are essential for the assembly and anchoring of cell-surface adhesins in Gram-positive bacteria. Thus, they play critical roles in virulence, infection and colonization by pathogens. Sortases have been classified into four types based on their primary sequence and the target-protein motifs that they recognize. All Gram-positive bacteria express a class A housekeeping sortase (SrtA). Sortase A from Streptococcus pneumoniae (NP_358691) has been crystallized in two crystal forms. Diamond-shaped crystals of Delta N(59)SrtA diffracted to 4.0 angstrom resolution and belonged to a tetragonal system with unit-cell parameters a = b = 122.8, c = 86.5 angstrom, alpha = beta = gamma = 90 degrees, while rod-shaped crystals of Delta N(81)SrtA diffracted to 2.91 angstrom resolution and belonged to the monoclinic space group P2(1) with unit-cell parameters a = 66.8, b = 103.47, c = 74.79 angstrom, alpha = gamma = 90, beta = 115.65 degrees. The Matthews coefficient (V(M) = 2.77 angstrom(3) Da(-1)) with similar to 56% solvent content suggested the presence of four molecules in the asymmetric unit for Delta N(81)SrtA. Also, a multi-copy search using a monomer as a probe in the molecular-replacement method resulted in the successful location of four sortase molecules in the asymmetric unit, with statistics R = 41.61, R(free) = 46.44, correlation coefficient (CC) = 64.31, CC(free) = 57.67

Effect of different temperatures on developmental periods and reproduction of fruit fly (Bactrocera cucurbitae)

Considering the economic value of cucurbits and the crop losses due to fruit fly infestation, the current experiment was carried out in controlled laboratory conditions to investigate the effects of temperature on the growing durations and reproduction of fruit fly as a response to climate change. At first, the culture of cucurbit fruit fly (infested bitter gourd fruits) was collected from the experimental field of the Department of Entomology, Bangabandhu Sheikh Mujibur Rahman Agricultural University and then the emerged larvae were artificially reared on bitter gourd slices under laboratory conditions at 25°C, 30°C and 35°C. Differences among the three tested temperatures for different developmental periods were significant, but the differences in male-female ratio at different temperatures were not statistically significant. The duration of life stages was significantly shorter when reared at high temperature (35°C) than when reared at low temperature (25°C). The incubation period and the durations of larval and pupal development of the insect decreased from 17.07±0.09 hours to 15.87±0.03 hours, 5.31±0.03 days to 3.40±0.08 days and 8.83±0.01 days to 8.08±0.04 days, respectively due to the increase of temperature from 25°C to 35°C. The mating duration, fecundity, hatching percentages were maximum at 25°C (3.54±0.01 days, 74.93±0.07 and 86.67±0.03%, respectively). Although some reproductive parameters were favored at 25°C, the results clearly indicate that an increase in temperature in the context of climate change would benefit the insect with more females and more generations per year due to having a short life cyc