African trypanosomes are capable of both pyrimidine biosynthesis and salvage of preformed pyrimidines from the host. However, uptake of pyrimidines in bloodstream form trypanosomes has not been investigated, making it difficult to judge the relative importance of salvage and synthesis or to design a pyrimidine-based chemotherapy. Detailed characterization of pyrimidine transport activities in bloodstream form Trypanosoma brucei brucei found that these cells express a high-affinity uracil transporter (designated TbU3) that is clearly distinct from the procyclic pyrimidine transporters. This transporter had low affinity for uridine and 2′deoxyuridine and was the sole pyrimidine transporter expressed in these cells. In addition, thymidine was taken up inefficiently through a P1-type nucleoside transporter. Of importance, the anticancer drug 5-fluorouracil was an excellent substrate for TbU3, and several 5-fluoropyrimidine analogs were investigated for uptake and trypanocidal activity; 5F-orotic acid, 5F-2′deoxyuridine displayed activity in the low micromolar range. The metabolism and mode of action of these analogs was determined using metabolomic assessments of T. brucei clonal lines adapted to high levels of these pyrimidine analogs, and of the sensitive parental strains. The analysis showed that 5-fluorouracil is incorporated into a large number of metabolites but likely exerts toxicity through incorporation into RNA. 5F-2′dUrd and 5F-2′dCtd are not incorporated into nucleic acids but act as prodrugs by inhibiting thymidylate synthase as 5F-dUMP. We present the most complete model of pyrimidine salvage in T. brucei to date, supported by genome-wide profiling of the predicted pyrimidine biosynthesis and conversion enzymes.

The aim was to build an educational website to teach preschoolers aged 2-5 years old some skills; related to reading, writing and pronouncing alphabet, numbers, animal names, shapes and other common words. Also, assist parents and teachers by providing digital game-based learning environment to “edutainment” the children. The study illustrated the usability and usefulness of this educational game-based website and provided future insights for researchers and developers to take into account in future work.

one of the challenges recently occurred in the concept of hiding data is the

robustness of hiding data in the way that is difficult to access or detect. Most of the steganography

schemes are based commonly on embed data within images or video frames on their original form

(uncompressed domain).

This paper presents a new methodology for data hiding in MPEG-2 video standard. Data will be

embedding during the compression stage of the AVI-MPEG2 encoding. The BPCS algorithm has

been modified and used in all our experiments for embed data, and the DES (Data Encryption

Standard) algorithm has been used to encrypt data before hiding. It only embeds encrypted data

bits in the quantized AC coefficients (low-frequency AC coefficients) of Y components (Luminance)

for the I-Frame. The obtained results demonstrate that the proposed method has the considerable

advantage over previous steganography schemes with a good PSNR values for the embedded

With the development of the internet and multimedia technology digital video encryption has attracted a great deal of

research interest in the recent few years in applications. In this paper, we propose a method to encrypt video data. The proposed

algorithm is based on the MPEG video coding standard. It selectively encrypts some DCT coefficients in the I frame, B frame and P

frame in MPEG video compression by using chaotic systems. The key in this paper is chaotic sequence based on logistic mapping. It

can produce the pseudo-random sequences with good randomness. The experimental results based on chaotic maps prove the

effectiveness of the proposed method, showing advantages of large key space and high-level security. The proposed algorithm was

measured through a series of tests and achieved good results. The results indicate that the algorithm can be implemented for video

encryption efficiently and it provides considerable levels of security

This paper proposes an estimation method based on the reflection of the (manifest) explanatory variable to estimate the parameters of a simple linear regression model when both response and explanatory variables are subject to measurement error (ME). The reflection method (RM) uses all observed data points, and does not exclude or ignore part of the data or replace them by their ranks. The RM is straightforward, and easy to implement. We show that the RM is equivalent or asymptotically equivalent to the orthogonal regression (OR) method. Simulation studies show that the RM produces estimators that are nearly asymptotically unbiased and efficient under the assumption that the ratio of the error variances equals one. Moreover, it allows to define the sum of squares of errors uniquely, the same way as in the case of no measurement error. Simulation based numerical comparisons of the RM with the ordinary least square (OLS) and OR methods are also included.

The classic problem for a logistically evolving single species population being harvested involves three parameters: rate constant, carrying capacity and harvesting rate, which are taken to be positive constants. However, in real world situations, these parameters may vary with time. This paper considers the situation where these vary on a time scale much longer than that intrinsic to the population evolution itself. Application of a multiple time scale approach gives approximate explicit closed form expressions for the changing population, that compare favorably with those generated from numerical solutions.

Given the pressing need for new antiprotozoal drugs without cross-resistance with current (failing) chemotherapy, we have explored 3-tridecylpyridinium alkaloids (3TPAs), derivatives of viscosamine, as antiparasitic agents. We have developed a simple synthetic route toward viscosamine and related cyclic and linear monomers and oligomers. Evaluation for cytotoxicity on the protozoan parasites Trypanosoma brucei, Leishmania spp., and Plasmodium falciparum revealed several 3TPAs with antiprotozoal activity in the nanomolar range. Their promising selectivity index in vitro prompted us to study the dynamics of cytotoxicity on trypanosomes in more detail. Parasites were killed relatively slowly at therapeutically safe concentrations, in a process that did not target the cell cycle. Clearance of T. brucei cultures was observed at drug concentrations of 1–10 μM.

Digital video steganography has attracted a great deal of research interest in the recent few years in applications. In this paper, we propose a method to embed and encrypt messages into video sequences by using steganography technique Based on the H.264 video coding standard. The system implemented in this work provides robust H.264 video compression constant, without significantly affecting the overall bit rate and quality of the video stream. The results indicate that the algorithm can be implemented steganography fast and efficiently and effect vision and peak signal to noise ratio (PSNR) of video sequences are almost unaffected after decoding.

Steganography is the idea of embedding a secret data in different media and has become an important regulation of methods of data integration. Although the still images are generally applied in the past, is very popular in recent years for the video. The techniques of video data hiding in recent year’s emphasis on the features generated by the video compression standard, a safer method for steganography uses MPEG-4/H.264 Bit Plane Complexity Segmentation (BPCS) algorithm is proposed in this approach. The reason for choosing such a video coverage is the enormous amount of data that can be hidden in each frame of MPEG-4 video. In other words, MPEG-4 has three types of images: I-frame, B, and P frames. Unlike other techniques used to hide data, such as the LSB algorithm, PBCS can achieve better results in both mathematics expression and human vision. In this paper, data is embedded in the videos of the I-frame until the BPCS can reach high levels of integration with low distortion based on the theory that regions of low noise-levels as in a picture can be replaced by noise without a significant loss of image quality. This approach invents data hidden in high-security environments. Experimental results show the success of hidden data in the selected and extracted data from the sequence of frames and also indicate the effectiveness of the implementation plan of steganography compressed video with high security features.

Few studies have systematically addressed evolutionary changes in olfactory neuron assemblies, either by genetic drift or as an

adaptation to specific odor environments. We have studied the sense of olfaction in 2 congeneric scarab beetles, Pachnoda

interrupta Olivier and Pachnoda marginata Drury (Coleoptera: Scarabaeidae: Cetoniinae), which are both opportunistic

polyphages, feeding mainly on fruit and flowers. The 2 species occur in dissimilar habitats: P. interrupta is found in dry

savannah, and P. marginata in tropical parts of equatorial Africa. To study how these species may have adapted their sense of

olfaction to their odor environments, we utilized single-unit electrophysiology on olfactory sensilla with a wide selection of

food-related compounds. Despite the differences in habitat, we found that the species shared most of the physiological types

of olfactory receptor neurons (ORNs) encountered, although their proportions frequently varied between the species. The high

degree of conservation in olfaction between the species implies that a similar sensory strategy is efficient for food search in

both habitats. However, shifts in proportions of receptor neuron classes, and slight shifts in response profiles and/or presence

of some ORN classes unique to either species, may reflect adaptation to a different set of hosts.

Key words: comparative study, electrophysiology, olfaction, polyphagous herbivore, single sensillum recordings