教学课程资源库 更多>>

ISBN: (纸本)9787115572820

关键词： Blockchain   Insurance   Games   Contracts   Consensus protocol   Computer science   Bitcoin   Blockchain   sharding   cyber insurance   discouragement attack   Stackelberg game   contract theory  

摘要： Sharding is a promising solution to achieving scalability within the blockchain network. A sharded blockchain network consists of a beacon chain and several committees powered by the participants (i.e., validators) through the Proof-of-Stake (PoS) consensus protocol. Efficient and scalable as it can be, the sharded blockchain based on PoS is vulnerable to discouragement attack. A discouragement attack occurs when malicious validators censor messages to discourage validators from participating in the network. Furthermore, no rate-limiting validator rotation (enter/exit quickly) makes it more challenging to detect such an attack. In this paper, considering the undetermined rotation and the discouragement attack, we render the beacon chain an intermediary, allowing the beacon chain to interact with validators and the cyber-insurer, aiming to encourage the validators' stable rotation through insurance compensation. Specifically, we utilize a two-stage hierarchical game-based model to formulate the complicated interactions under the cyber insurance framework. In the first stage, the beacon chain develops compensatory strategies according to the insurer's profile. In the second stage, the beacon chain designs a series of contracts for validators, including insurance items, compensatory strategies, and rotation requirements. Consequently, the proposed scheme incentivizes validators to remain online by transferring risk to the cyber insurer and enables the sharded blockchain network to weaken the attack's impact through validators' stable rotation. This paper presents closed-form solutions for the proposed model, in which the beacon chain and the cyber insurer can gain maximized profits. The simulations demonstrate the feasibility and superiority of the proposed model.

关键词： Active Shooters   Criminological theory   Diversity training   Gun-control   Historical homicide rates   Human-analytics   Trauma Informed practices   Me Too   ANTIFA   Black Lives Matter   Cancel Culture  

摘要： This paper develops and applies a comprehensive theoretical synthesis to help explain the inverse relationship between General Homicide and Active Shooter rates over the past two decades. Organizing various micro, meso and macro criminological perspectives under the banner of the three Routine Activities Theory categories Motivation, Means and Opportunity, helps explain why over the past two decades the General Homicide rate has been decreasing, while Active Shootings have been rising. Possibly inadvertently contributing to this trend is the emergent synthesis of the "Me Too", ANTIFA and Black Lives Matter movements under the general political correctness ethos "Cancel Culture". Drawing upon the theoretical conclusions, we offer suggestions for how communities and organizations like schools and workplaces can mitigate risk through a tri-part approach that simultaneously addresses the Motivation, Means and Opportunity that enable Active Shooters.

关键词： Food quality   Fungal spoilage   Hot fill   Postprocessing contamination  

摘要： Black yeasts are a functional group that has caused spoilage in cold-filled and hot-filled beverages, as well as other water activity-controlled food products. We established quantitative thermoresistance parameters for the inactivation of 12 Aureobasidium and Exophiala isolates through isothermal experiments and a challenge study. Culture age (2 versus 28 days) variably affected the thermoresisitance among the black yeast strains. Variation in thermoresistance exists within each genus, but the two most resistant strains were the Exophiala isolates. The two most heat-resistant isolates were Exophiala phaeomuriformis FSL-E2-0572, with a D60-value of 7.69 +/- 0.63 min in 28-day culture and Exophiala dermatitidis YB-734, with a D60-value of 16.32 +/- 2.13 min in 28-day culture. Although these thermoresistance levels were, in some cases, greater than those for conidia and vegetative cells from other common food spoilage fungi, they were much more sensitive than the ascospores of heatresistant molds most associated with spoilage of hot-filled products. However, given that black yeasts have caused spoilage in hot-filled products, we hypothesized that this intermediate degree of thermoresistance may support survival following introduction during active cooling before package seals have formed. A challenge study was performed in an acidic (apple cider) and water activity-controlled (maple syrup) product to evaluate survival. When apple cider was hot filled at 828C, black yeast counts were reduced by 4.1 log CFU/mL 24 h after the heat treatment, but the survivors increased up to 6.7 log CFU/mL after 2 weeks. In comparison, the counts were below the detection limit after both 24 h and 14 days of shelf life in both products when filled at the boiling points. This suggests that ensuring water microbial quality in cooling tunnels and nozzle sanitation may be essential in mitigating the introduction of these fungi.

关键词： Digital forensics   Cybersecurity   Computer science   Education   Curriculum  

摘要： We present a comprehensive review of digital forensics programs offered by universities across the United States (U.S.). While numerous studies on digital forensics standards and curriculum exist, few, if any, have examined digital forensics courses offered across the nation. Since digital forensics courses vary from university to university, online course catalogs for academic institutions were evaluated to curate a dataset. Universities were selected based on online searches, similar to those that would be made by prospective students. Ninety-seven (n = 97) degree programs in the U.S. were evaluated. Overall, results showed that advanced technical courses are missing from curricula. We conclude that most degree programs evaluated offer legal/cyber law & ethics, investigative processes, and lab & forensic operations courses. The courses offered the least were memory forensics, Internet of Things (loT) forensics, and program & software forensics. The data shows that some universities with the Forensic Science Education Programs Accreditation Commission (FEPAC) accreditation are lacking instruction in timely digital forensics topics such as memory forensics (0%), hardware security (0%), program & software forensics (0%), and ethical hacking (0%). Investigative processes (100%), network forensics (100%), lab & forensic operations (100%), and a senior design/capstone project (100%) are offered at all FEPAC accredited universities in digital forensics and digital evidence. Undergraduate degree programs with the National Centers of Digital Forensics Academic Excellence (CDFAE) designation had over a 50% offering rate for 11 out of the 22 courses we evaluated. However, memory forensics (0%) and loT forensics (12.5%) were largely underrepresented. Our work provides an overview of the current state of digital forensics programs and discusses the importance of these courses to educate the next digital forensics workforce. (C) 2021 The Author(s). Published by Elsevier Ltd.

摘要： Brian Mitzman, MD Central Message The education of cardiothoracic trainees has been drastically impacted by the COVID-19 pandemic. We must assess their current skillset and supplement missing experiences with increased simulation. See Article page...

ISBN: (纸本)9787115570703

关键词： Navigation   Silicon compounds   Robot kinematics   Biological system modeling   System recovery   IEEE transactions   Computer science   multi agent systems   navigation   multi agent coordination  

摘要： Multi-agent navigation in restricted environments presents significant challenges, since agents need to move to their goals in an efficient manner while avoiding collisions with both static and dynamic obstacles. Previously, C-Nav was proposed as a method that can effectively coordinate groups of agents in very restricted environments. In this work, we propose and evaluate three alternative communications models for C-Nav, that intend to provide more flexibility to the original method. The results of our experiments show that each of our proposed methods can lead to significant improvements over C-Nav in specific types of restricted environments.

关键词： COVID-19   Emergency remote teaching   Online education   Students’ experience   Survey study  

摘要： In the first 6 months of 2020, the COVID-19 pandemic forced numerous universities across the globe to quickly transfer all their courses online, a response known as Emergency Remote Teaching. Courses initially designed for face to face delivery had to be quickly adapted to a new online format. In this paper, we study the perception of the transition to remote teaching in a group of computer science students. Despite the advantage given by an average higher computer literacy, the results of this study suggest that students found the transition challenging, especially regarding tasks such as asking questions during video lectures and interacting with instructors. The transition seems to have had a greater impact on students of lower level courses. Differences were found also across race and residence status (but not gender). The initial format of the course was also relevant: students fared better if their course relied on online tools before the transition. © 2021, The Author(s), under exclusive licence to Springer Nature Singapore Pte Ltd.

关键词： Biomedical measurement   Fuzzy logic   Automata   Computer science   Probabilistic logic   Discrete-event systems   Current measurement   Fuzzy automata   fuzzy discrete event systems (DESs)   fuzzy logic   opacity measures  

摘要： Opacity, as an important security property, has been well investigated in crisp discrete event systems. However, in some practical systems, the general behaviors, secret and nonsecret behaviors obtained by the intruder need to be expressed as fuzzy sets rather than crisp sets. Under this situation, the intruder makes inferences by fuzzy logic rather than classic logic, thus the notions of the fuzzy opacity measures are desired to be established. First, by means of the basic laws of fuzzy logic, a general fuzzy opacity measure, as a template, is presented, in this article, for the given generalized characterizations of secret and nonsecret behaviors. Moreover, a specific measure, called as fuzzy initial-final opacity (FIFO) measure, is investigated under the assumption that the secrets and nonsecrets can be coded into the initial-final state-pairs. In addition, two variants of FIFO measure are also proposed under the assumptions that the secrets and nonsecrets are only related to the initial-states or final-states. With these fuzzy opacity measures, the system designers can evaluate the opacity degree of the systems to be designed. To show the applicability of the fuzzy opacity measures to practical systems, we finally present an illustrative example of evaluating the location privacy protection systems in location-based services by means of the fuzzy opacity measures.