Comments on ＂How to repair the Hill cipher＂

A modification of the Hill cipher algorithm was recently proposed by Ismail et al.（2006）, who claimed that their new scheme could offer more security than the original one due to an extra non-linearity layer introduced via an elaborated key generation mechanism. That mechanism produces one different encryption key for each one of the plaintext blocks. Nevertheless, we show in this paper that their method still has severe security flaws whose weaknesses are essentially the same as that already found in the original Hill cipher scheme.     

每个孩子都是童画家

正艺术教育,听起来似乎很遥远,但实际,它就散播在生活的每个角落里。一个18岁时就被誉为是高级画师,工作后设计的作品被惠普公司永久收藏的S老师;一个自称是中国传统美学教育的典型失败案例的摄影爱好者F老师。他们义无反顾地投身于孩子的艺术     

Perceptual completion in newborn human infants

Despite decades of studies of human infants, a still open question concerns the role of visual experience in the development of the ability to perceive complete shapes over partial occlusion. Previous studies show that newborns fail to manifest this ability, either because they lack the visual experience required for perceptual completion or because they fail to detect the pattern of motion. To distinguish these possibilities, newborns' perception of a center-occluded object was tested, using stroboscopic motion. Infants (mean age of 72 hr) perceived the object as a connected unit, providing the first evidence that the newborn is capable of filling in gaps in the visible surface layout when the relevant visual information can be detected by his or her immature visual system.     

Can the punishment fit the crime when suspects confess child sexual abuse?

OBJECTIVE: To determine significant predictors of severity of sentencing of sex offenders of minors in a jurisdiction which obtains many confessions. METHOD: Data were abstracted from 323 criminal court case records of sexually abused minors over 11 years in a county which places a high priority on sexual abuse prosecution. The sample used in this analysis consisted of 218 men who received a sentence for a sex offense. Multiple regression analysis was used to examine what factors predicted severity of sentences. Specifically this study explores whether, in a county which is very successful in obtaining confessions to sexual abuse of children, the severity of sentence is explained by the seriousness of the crime (more severe type of sexual abuse, younger age of the victim, prior conviction of a sex offense, and abusing more than one child), or by factors unrelated to the seriousness of the offense, offender confession and/or having a court-appointed attorney. RESULTS: Factors that predicted the severity of the sentence were the seriousness of the sex crime, prior conviction of a sex crime, and young age of the victim. CONCLUSIONS: This community, with a high confession rate and a high conviction rate, imposed sentences that were consistent with the crimes, with more severe sentences for more serious crimes. Convenience factors, such as the fact the offender confessed, and systemic factors, such as having a court-appointed attorney, did not result in more severe sentences.     

Surveillance of viral contamination of invasive medical instruments in dentistry

Objective： To investigate the viral contamination of invasive medical instruments in dentistry and to provide health administrative institutions with surveillance data. Methods： Sterilized samples were randomly collected from the department of dentistry to detect HBV-DNA, HCV-RNA, HIV-RNA and HBsAg. Results： Of the invasive medical instruments that were sterilized with 2% glutaraldehyde, one of the samples was positive for HBV-DNA, and another sample was positive for HBsAg. Conclusion： Though massive virus contamination of invasive medical instruments in dentistry has been reduced to a low level, the occurrence of contamination still remains.