Chris J. Mitchell

Bio: Chris J. Mitchell is an academic researcher from Royal Holloway, University of London. The author has contributed to research in topics: Authentication & Cryptography. The author has an hindex of 48, co-authored 397 publications receiving 10982 citations. Previous affiliations of Chris J. Mitchell include Johns Hopkins University & University of Portland.

Glucose Homeostasis in Mice Is Transglutaminase 2 Independent

Abstract: Transglutaminase type 2 (TG2) has been reported to be a candidate gene for maturity onset diabetes of the young (MODY) because three different mutations that impair TG2 transamidase activity have been found in 3 families with MODY. TG2 null (TG2−/−) mice have been reported to be glucose intolerant and have impaired glucose-stimulated insulin secretion (GSIS). Here we rigorously evaluated the role of TG2 in glucose metabolism using independently generated murine models of genetic TG2 disruption, which show no compensatory enhanced expression of other TGs in pancreatic islets or other tissues. First, we subjected chow- or fat-fed congenic SV129 or C57BL/6 wild type (WT) and TG2−/− littermates, to oral glucose gavage. Blood glucose and serum insulin levels were similar for both genotypes. Pancreatic islets isolated from these animals and analysed in vitro for GSIS and cholinergic potentiation of GSIS, showed no significant difference between genotypes. Results from intraperitoneal glucose tolerance tests (GTTs) and insulin tolerance tests (ITTs) were similar for both genotypes. Second, we directly investigated the role of TG2 transamidase activity in insulin secretion using a coisogenic model that expresses a mutant form of TG2 (TG2R579A), which is constitutively active for transamidase activity. Intraperitoneal GTTs and ITTs revealed no significant differences between WT and TG2R579A/R579A mice. Given that neither deletion nor constitutive activation of TG2 transamidase activity altered basal responses, or responses to a glucose or insulin challenge, our data indicate that glucose homeostasis in mice is TG2 independent, and question a link between TG2 and diabetes.

Remote user authentication using public information

Abstract: A method for remote user authentication is proposed that requires only public information to be stored at the verifying host. Like the S/KEY scheme, the new technique uses only symmetric cryptography and is resistant to eavesdropping, but, unlike S/KEY, it is resistant to host impersonation attacks. The avoidance of asymmetric cryptographic techniques makes the scheme appropriate for low cost user authentication devices.

Attention and relative novelty in human perceptual learning.

Abstract: Four experiments examined the role of attention in human perceptual learning. In Experiment 1, participants were preexposed to a pair of visual (checkerboard) stimuli AX and BX, with common elements X and unique features A and B. A same-different task was then used to assess discrimination of AX and BX and a pair of control stimuli, CY and DY. In addition, participants' eye movements were recorded to assess the role of attentional processes. The results showed that preexposure enhanced discrimination between AX and BX. Furthermore, participants showed greater attention to the preexposed unique features A and B than to the novel unique features C and D, as measured by the eye gaze monitor. Experiments 2 and 3 examined the prediction that perceptual learning is due to the relative familiarity of the common and unique stimulus features. Experiment 4 replicated the intermixed-blocked effect and showed that the way in which AX and BX are presented is also important for perceptual learning. The results generally support the idea that intermixed preexposure to AX and BX increases attention to the unique stimulus features A and B. Some aspects of the results are consistent with a relative novelty account, whereas others implicate a high-level attentional process that is not driven by stimulus novelty.

The propositional basis of cue-controlled reward seeking

Abstract: Two experiments examined the role of propositional and automatic (ideomotor) processes in cue-elicited responding for rewarding outcomes (beer and chocolate). In a training phase, participants earned either chocolate or beer points by making one of two button-press responses. Rewards were indicated by the presentation of chocolate and beer pictures. On test, each trial began with a picture of beer or chocolate, or a blank screen, and choice of the beer versus chocolate response was assessed in the presence of these three pictures. Participants tended to choose the beer and chocolate response in the presence of the beer and chocolate pictures, respectively. In Experiment 1, instructions signalling that the pictures did not indicate which response would be rewarded significantly reduced the priming effect. In Experiment 2, instructions indicating that the pictures signified which response would not be rewarded resulted in a reversed priming effect. Finally, in both experiments, the priming effect correlated...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

Handbook of Applied Cryptography

Abstract: From the Publisher: A valuable reference for the novice as well as for the expert who needs a wider scope of coverage within the area of cryptography, this book provides easy and rapid access of information and includes more than 200 algorithms and protocols; more than 200 tables and figures; more than 1,000 numbered definitions, facts, examples, notes, and remarks; and over 1,250 significant references, including brief comments on each paper.

Tissue-based map of the human proteome

Abstract: Resolving the molecular details of proteome variation in the different tissues and organs of the human body will greatly increase our knowledge of human biology and disease. Here, we present a map of the human tissue proteome based on an integrated omics approach that involves quantitative transcriptomics at the tissue and organ level, combined with tissue microarray-based immunohistochemistry, to achieve spatial localization of proteins down to the single-cell level. Our tissue-based analysis detected more than 90% of the putative protein-coding genes. We used this approach to explore the human secretome, the membrane proteome, the druggable proteome, the cancer proteome, and the metabolic functions in 32 different tissues and organs. All the data are integrated in an interactive Web-based database that allows exploration of individual proteins, as well as navigation of global expression patterns, in all major tissues and organs in the human body.

Differential Power Analysis

Abstract: Cryptosystem designers frequently assume that secrets will be manipulated in closed, reliable computing environments. Unfortunately, actual computers and microchips leak information about the operations they process. This paper examines specific methods for analyzing power consumption measurements to find secret keys from tamper resistant devices. We also discuss approaches for building cryptosystems that can operate securely in existing hardware that leaks information.