A new image encryption scheme, based on a total shuffling and parallel encryption algorithm is proposed in this paper. Two chaotic systems have been used in the encryption algorithm to confuse the relationship between the plain-image and the cipherimage. To make the encryption procedure more confusing and complex, the plain-image is first divided into 4 sub-images and then the position of each subimage is changed pseudo-randomly according to a logistic map. Next, a total shuffling matrix is used to shuffle the position of pixels in the whole image and then sub-images are encrypted simultaneously in a parallel manner. The experimental results on USC data base demonstrate that the proposed encryption algorithm has a low time complexity and has the advantages of large key space and high security. Moreover, the robustness of this locally encryption method is much more in contrast with other encryption schemes and the distribution of gray values has a random-like behavior in the encrypted image.

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Background: Aggression is a complex behavior affected by different psychological, genetic, and biological factors. Nutrition is an important factor affecting aggressive behavior. Objectives: The aim of the present research was to study the effect of cold and hot nature food on students' mental health and aggressive behavior. Materials and Methods:In a quasi-experimental study, we recruited 61 normal students in Gonabad University of Medical Sciences during summer semester. The students were randomly allocated into three groups for three weeks, of which one group was served with food of normal nature, the second with hot food and the third group with food of cold nature. Students' mental health and aggressive behavior were measured by General Health Questionnaire (GHQ-28) and Buss and Perry Aggression Questionnaire before and after intervention. Results: There were no significant differences in demographic characteristics and physical examination among students of three groups (P > 0.05). There was no significant difference regarding mental health and its components after serving the students with normal, hot, or cold nature food (P > 0.05). No significant differences in aggressive behavior and associated factors were found among three groups of students before and after intervention (P > 0.05). Conclusions:The findings of this study showed that cold and hot nature of food had no effect on students' mental health and aggressive behavior.

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