Polymer-stabilized sialylated nanoparticles : synthesis, optimization, and differential binding to influenza hemagglutinins

During influenza infection, hemagglutinins (HAs) on the viral surface bind to sialic acids on the host cell's surface. While all HAs bind sialic acids, human influenza targets terminal α2,6 sialic acids and avian influenza targets α2,3 sialic acids. For interspecies transmission (zoonosis), HA must mutate to adapt to these differences. Here, multivalent gold nanoparticles bearing either α2,6- or α2,3-sialyllactosamine have been developed to interrogate a panel of HAs from pathogenic human, low pathogenic avian, and other species' influenza. This method exploits the benefits of multivalent glycan presentation compared to monovalent presentation to increase affinity and investigate how multivalency affects selectivity. Using a library-orientated approach, parameters including polymer coating and core diameter were optimized for maximal binding and specificity were probed using galactosylated particles and a panel of biophysical techniques [ultraviolet-visible spectroscopy, dynamic light scattering, and biolayer interferometry]. The optimized particles were then functionalized with sialyllactosamine and their binding analyzed against a panel of HAs derived from pathogenic influenza strains including low pathogenic avian strains. This showed significant specificity crossover, which is not observed in monovalent formats, with binding of avian HAs to human sialic acids and in agreement with alternate assay formats. These results demonstrate that precise multivalent presentation is essential to dissect the interactions of HAs and may aid the discovery of tools for disease and zoonosis transmission

Stock options and managers' incentives to cheat

This paper develops a continuous-time real options' pricing model to study managers' incentives to cheat in the presence of equity-based compensation plans. It shows that managers' incentives to cheat are strongly influenced by the efficiency of the justice. The model's main result is that managers have greater incentives to commit fraudulent actions under stock options than under common stocks based compensation plan

No-Regret Learning in Extensive-Form Games with Imperfect Recall

Counterfactual Regret Minimization (CFR) is an efficient no-regret learning algorithm for decision problems modeled as extensive games. CFR's regret bounds depend on the requirement of perfect recall: players always remember information that was revealed to them and the order in which it was revealed. In games without perfect recall, however, CFR's guarantees do not apply. In this paper, we present the first regret bound for CFR when applied to a general class of games with imperfect recall. In addition, we show that CFR applied to any abstraction belonging to our general class results in a regret bound not just for the abstract game, but for the full game as well. We verify our theory and show how imperfect recall can be used to trade a small increase in regret for a significant reduction in memory in three domains: die-roll poker, phantom tic-tac-toe, and Bluff.Comment: 21 pages, 4 figures, expanded version of article to appear in Proceedings of the Twenty-Ninth International Conference on Machine Learnin

Infinite alphabet passwords-a unified model for a class of authentication systems

In the paper we propose a formal model for class of authentication systems termed, “Infinite Alphabet Password Systems” (IAPs). We define such systems as those that use a character set for the construction of the authentication token that is theoretically infinite, only bound by practical implementation restrictions. We find that the IAP architecture can feasibly be adapted for use in many real world situations, and may be implemented using a number of system architectures and cryptographic protocols. A security analysis is conducted on an implementation of the model that utilizes images for its underlying alphabet. As a result of the analysis we find that IAPs can offer security benefits over traditional alphanumeric password schemes. In particular some of the significant problems concerning phishing, pharming, replay, dictionary and offline brute force attacks are mitigated

Cyber stalking is a social evil: from the Indian women's perspective

We discuss the causes and impacts of selected cyber stalking cases against women in India as evidenced from the literature and conducted interviews. We find that the prevailing social and cultural value system and norms in India can prevent women from approaching police or registering legal complaints. The few studies to-date in the Indian context, indicate the high prevalence and serious impacts cyber stalking has on the victims’ psychological and physical state. Our work further confirms this. Moreover, interviewees describe secondary victimizations experienced via the actions of friends and relatives. We observe this to be a form of social punishment stemming from gender-related beliefs and attitudes that seem to be normative in India. These secondary victimizations described had far reaching, long term implications, exacerbating the already high levels of distress typically experienced during cases of cyber stalking

The social, legal, technical perspective of cyber stalking in India

This paper explores the social, technical and legal perspectives of cyberstalking in India. With the growth of the Internet, cyberstalking as a potential cybercrime has achieved many fold growths in India over the last decade. Factors such as, poor social perception towards the crime, cultural conflict and ignorance, subjective characteristics and habits of the victims, freedom and remoteness of Internet technologies and inadequacy of cyber legislation in preventing and penalising the crime have facilitated the rapid growth and proliferation of cyberstalking in India. In addition to low levels of awareness on the part of the victim and law enforcement authorities, anecdotal evidence suggests there is a fear of secondary victimisation, both in victims and their relatives. This has become a major cause for the majority of stalking crimes to remain unregistered. In case of India, there is clear dearth of research in relation to the social, legal and technical perspectives of cyberstalking. None of the Indian studies have provided conclusive findings on these three perspectives. This paper recommends further comprehensive studies into cyberstalking in India

Update on Radiation Testing for Space Fission Power Systems

Radiation effects on materials and electronics is a major topic that needs to be addressed for a nuclear reactor flight demonstration of the Kilopower reactor. The Kilopower project team has taken steps towards developing a standardized radiation environment qualification program for components and materials. Candidate nuclear reactor facilities for both low fluence electronics and high fluence materials irradiations have been identified and approached. Collaborations are being pursued with both NASA and external experts to ensure that the results of the qualification testing are appropriate and relevant to nuclear fission power flight systems

Sandwich Core Heat-Pipe Radiator for Power and Propulsion Systems

Next-generation heat-pipe radiator technologies are being developed at the NASA Glenn Research Center to provide advancements in heat-rejection systems for space power and propulsion systems. All spacecraft power and propulsion systems require their waste heat to be rejected to space in order to function at their desired design conditions. The thermal efficiency of these heat-rejection systems, balanced with structural requirements, directly affect the total mass of the system. Terrestrially, this technology could be used for thermal control of structural systems. One potential use is radiant heating systems for residential and commercial applications. The thin cross section and efficient heat transportability could easily be applied to flooring and wall structures that could evenly heat large surface areas. Using this heat-pipe technology, the evaporator of the radiators could be heated using any household heat source (electric, gas, etc.), which would vaporize the internal working fluid and carry the heat to the condenser sections (walls and/or floors). The temperature could be easily controlled, providing a comfortable and affordable living environment. Investigating the appropriate materials and working fluids is needed to determine this application's potential success and usage

Kilowatt-Class Fission Power Systems for Science and Human Precursor Missions

Nuclear power provides an enabling capability for NASA missions that might otherwise be constrained by power availability, mission duration, or operational robustness. NASA and the Department of Energy (DOE) are developing fission power technology to serve a wide range of future space uses. Advantages include lower mass, longer life, and greater mission flexibility than competing power system options. Kilowatt-class fission systems, designated "Kilopower," were conceived to address the need for systems to fill the gap above the current 100-Wclass radioisotope power systems being developed for science missions and below the typical 100-kWe-class reactor power systems being developed for human exploration missions. This paper reviews the current fission technology project and examines some Kilopower concepts that could be used to support future science missions or human precursors