A Novel (k,n) Secret Sharing Scheme from Quadratic Residues for Grayscale Images

A new grayscale image encryption algorithm based on $(k,n)$ threshold secret sharing is proposed. The scheme allows a secret image to be transformed into $n$ shares, where any $k \le n$ shares can be used to reconstruct the secret image, while the knowledge of $k-1$ or fewer shares leaves no sufficient information about the secret image and it becomes hard to decrypt the transmitted image. In the proposed scheme, the pixels of the secret image are first permuted and then encrypted by using quadratic residues. In the final stage, the encrypted image is shared into n shadow images using polynomials of Shamir scheme. The proposed scheme is provably secure and the experimental results shows that the scheme performs well while maintaining high levels of quality in the reconstructed image

Prefrontal involvement in imitation learning of hand actions : effects of practice and expertise.

In this event-related fMRI study, we demonstrate the effects of a single session of practising configural hand actions (guitar chords) on cortical activations during observation, motor preparation, and imitative execution. During the observation of non-practised actions, the mirror neuron system (MNS), consisting of inferior parietal and ventral premotor areas, was more strongly activated than for the practised actions. This finding indicates a strong role of the MNS in the early stages of imitation learning. In addition, the dorsolateral prefrontal cortex (DLPFC) was selectively involved during observation and motor preparation of the non-practised chords. This finding confirms Buccino et al.’s (2004a) model of imitation learning: for actions that are not yet part of the observer’s motor repertoire, DLPFC engages in operations of selection and combination of existing, elementary representations in the MNS. The pattern of prefrontal activations further supports Shallice’s (2004) proposal of a dominant role of the left DLPFC in modulating lower-level systems, and of a dominant role of the right DLPFC in monitoring operations

Nano-porosity in GaSb induced by swift heavy ion irradiation

Nano-porous structures form in GaSb after ion irradiation with 185 MeV Au ions. The porous layer formation is governed by the dominant electronic energy loss at this energy regime. The porous layer morphology differs significantly from that previously reported for low-energy, ion-irradiated GaSb. Prior to the onset of porosity, positron annihilation lifetime spectroscopy indicates the formation of small vacancy clusters in single ion impacts, while transmission electron microscopy reveals fragmentation of the GaSb into nanocrystallites embedded in an amorphous matrix. Following this fragmentation process, macroscopic porosity forms, presumably within the amorphous phase.The authors thank the Australian Research Council for support and the staff at the ANU Heavy Ion Accelerator Facility for their continued technical assistance. R.C.E. acknowledges the support from the Office of Basic Energy Sciences of the U.S. DOE (Grant No. DE-FG02-97ER45656)

Generation of the millisecond electron beam at forevacuum

The possibility of generation of a quasicontinuous electron beam with pulse duration up to 4.2 ms from arc discharge plasma in the forevacuum pressure range is presented. It is shown, that the voltage-current characteristic of the forevacuum plasma electron source generating millisecond electron beam has a "classical" form for electron sources with a plasma cathode

Butterflyfishes (Chaetodontidae) from Abu Hashish fringing reefs, Port Sudan, Red Sea

Using Reef Check Programme butterflyfishes of Abu Hashish fringing reefs were recorded during 2003 and 2013. The results showed that the numbers of species declined from nine to seven. Chi square test revealed that the number of butterflyfishes significantly decreased (p<0.00001). This reduction was attributed to continuous construction and anthropogenic actives Keywords: Butterflyfishes, Abu Hashish, Port Suda

How prior knowledge of LGB identities alters the effects of workplace disclosure

© 2017 Elsevier Inc. Decisions to reveal one\u27s sexual orientation are assumed to be a volitional choice. Prior research has shown, however, that people often learn about the lesbian, gay, or bisexual (LGB) identities of others through indirect means, such as gossip and stereotypical cues (Ambady, Hallahan, & Conner, 1999; Colgan, Creegan, McKearney, & Wright, 2007). We conduct two studies to determine the effects of these forms of prior identity-related knowledge on disclosure outcomes. First, a pre-test of study assumptions demonstrates that recipients of minority sexual orientation disclosures often have prior knowledge of those identities. Second, a survey study examining the target\u27s perspective finds that LGB people often suspect when others have prior knowledge of their identities, and this expected prior knowledge moderates the relationship between identity-management and subsequent experiences of discrimination. Lastly, a lab experiment manipulating the level of prior identity-related knowledge establishes that this information directly influences interpersonal workplace outcomes of disclosures through perceptions of awkwardness but not through liking. Together, these studies demonstrate support for our model of prior identity-related knowledge and highlight the importance of examining both prior identity-related knowledge as well as identity management strategies in predicting LGB workplace experiences

Predictors of HIV prevention knowledge and sexual behaviors among students at Makerere University Kampala, Uganda

Background: Prior reviews argue that unsafe sexual behaviors and poor HIV knowledge significantly increase the probability of acquiring HIV infections among adolescents. This study assessed the predictors of HIV prevention knowledge and sexual behaviors among Makerere university students in Uganda.   Methods: We performed a cross-sectional survey. We performed a normality test using Shapiro Wilk test on knowledge score. Results revealed that knowledge score was not normally distributed. The study used two sample Wilcoxon Rank Sum and Kruskal Wallis Rank tests to assess the effect of HIV knowledge on demographic characteristics and sexual behaviors. Post-hoc tests were conducted using Bonferroni correction. Spearman rank correlation test was used for continuous variables while Chi-square and Fisher’s tests were used for categorical variables to assess the relationship between demographic characteristics and sexual behaviors.     Results: We report results for 1337 students. The mean age was 21.2SD (1.6) and more than half 700(52.4%) were male students. The median HIV prevention knowledge score of students was 13 IQR (11-15) in the range of 0 to 18. Males significantly scored higher than females (13.0 IQR (12-15) vs. 12.0 IQR (10-14) p=0.000), an increase in age was associated with higher knowledge scores (Rho = 0.101, p = 0.000).   Students in the third year of study significantly scored higher than those in the first year, and government-sponsored students scored higher than the privately sponsored students. HIV knowledge was also significantly associated with sexual experience, and condom use at univariate level but insignificant at multiple level analysis. Males were more likely to have ever had sex (31.7% vs. 12.7%) and ever used a condom (63% vs. 55%) than females respectively   Conclusion: Our findings suggest that Makerere University students possessed good knowledge on HIV. There is evidence of an association between student’s knowledge, and demographic characteristics and a few sexual behaviors. Future behavioral and educational programs that target both sexually and non-sexually experienced students should address the gender differences

Altered processing of sensory stimuli in patients with migraine

Migraine is a cyclic disorder, in which functional and morphological brain changes fluctuate over time, culminating periodically in an attack. In the migrainous brain, temporal processing of external stimuli and sequential recruitment of neuronal networks are often dysfunctional. These changes reflect complex CNS dysfunction patterns. Assessment of multimodal evoked potentials and nociceptive reflex responses can reveal altered patterns of the brain's electrophysiological activity, thereby aiding our understanding of the pathophysiology of migraine. In this Review, we summarize the most important findings on temporal processing of evoked and reflex responses in migraine. Considering these data, we propose that thalamocortical dysrhythmia may be responsible for the altered synchronicity in migraine. To test this hypothesis in future research, electrophysiological recordings should be combined with neuroimaging studies so that the temporal patterns of sensory processing in patients with migraine can be correlated with the accompanying anatomical and functional changes

Latent ion tracks in amorphous silicon

We present experimental evidence for the formation of ion tracks in amorphous Si induced by swift heavy-ion irradiation. An underlying core-shell structure consistent with remnants of a high-density liquid structure was revealed by small-angle x-ray scattering and molecular dynamics simulations. Ion track dimensions differ for as-implanted and relaxed Si as attributed to differentmicrostructures andmelting temperatures. The identification and characterization of ion tracks in amorphous Si yields new insight into mechanisms of damage formation due to swift heavy-ion irradiation in amorphous semiconductors