An SDN-Based Authentication Mechanism for Securing Neighbor Discovery Protocol in IPv6

The Neighbor Discovery Protocol (NDP) is one of the main protocols in the Internet Protocol version 6 (IPv6) suite, and it provides many basic functions for the normal operation of IPv6 in a local area network (LAN), such as address autoconfiguration and address resolution. However, it has many vulnerabilities that can be used by malicious nodes to launch attacks, because the NDP messages are easily spoofed without protection. Surrounding this problem, many solutions have been proposed for securing NDP, but these solutions either proposed new protocols that need to be supported by all nodes or built mechanisms that require the cooperation of all nodes, which is inevitable in the traditional distributed networks. Nevertheless, Software-Defined Networking (SDN) provides a new perspective to think about protecting NDP. In this paper, we proposed an SDN-based authentication mechanism to verify the identity of NDP packets transmitted in a LAN. Using the centralized control and programmability of SDN, it can effectively prevent the spoofing attacks and other derived attacks based on spoofing. In addition, this mechanism needs no additional protocol supporting or configuration at hosts and routers and does not introduce any dedicated devices

Genetic Evidence for Elevated Pathogenicity of Mitochondrial DNA Heteroplasmy in Autism Spectrum Disorder

Increasing clinical and biochemical evidence implicate mitochondrial dysfunction in the pathophysiology of Autism Spectrum Disorder (ASD), but little is known about the biological basis for this connection. A possible cause of ASD is the genetic variation in the mitochondrial DNA (mtDNA) sequence, which has yet to be thoroughly investigated in large genomic studies of ASD. Here we evaluated mtDNA variation, including the mixture of different mtDNA molecules in the same individual (i.e., heteroplasmy), using whole-exome sequencing data from mother-proband-sibling trios from simplex families (n = 903) where only one child is affected by ASD. We found that heteroplasmic mutations in autistic probands were enriched at non-polymorphic mtDNA sites (P = 0.0015), which were more likely to confer deleterious effects than heteroplasmies at polymorphic mtDNA sites. Accordingly, we observed a ~1.5-fold enrichment of nonsynonymous mutations (P = 0.0028) as well as a ~2.2-fold enrichment of predicted pathogenic mutations (P = 0.0016) in autistic probands compared to their non-autistic siblings. Both nonsynonymous and predicted pathogenic mutations private to probands conferred increased risk of ASD (Odds Ratio, OR[95% CI] = 1.87[1.14–3.11] and 2.55[1.26–5.51], respectively), and their influence on ASD was most pronounced in families with probands showing diminished IQ and/or impaired social behavior compared to their non-autistic siblings. We also showed that the genetic transmission pattern of mtDNA heteroplasmies with high pathogenic potential differed between mother-autistic proband pairs and mother-sibling pairs, implicating developmental and possibly in utero contributions. Taken together, our genetic findings substantiate pathogenic mtDNA mutations as a potential cause for ASD and synergize with recent work calling attention to their unique metabolic phenotypes for diagnosis and treatment of children with ASD

Sierra Nevada Journeys: Strategic Expansion Plan 2016

Sierra Nevada Journeys (SNJ) is an outdoor education organization that has grown substantially since its founding in 2006. The organization offers a variety of programs to students in California and Nevada, but currently lacks the infrastructure necessary to meet increased demand and provide optimal outdoor education experiences for its students. As the organization prepares to receive a large land donation from their parent organization, the Sierra Health Foundation, they reached out to the University of Michigan’s School of Natural Resources and Environment to receive guidance on how best to approach their expansion. Originally, the organization sought guidance in deciding how they should proceed with meeting increased demand, whether this should be completed through physical campus expansion or instead through curriculum expansion to host students throughout the year (later referred to as “winterization”). As the project evolved, the organization gained a better idea of its needs and available resources, including a future donation by Sierra Health Foundation of the land where Grizzly Creek Ranch (GCR), their 1,500-acre outdoor education learning center, is located. With this new information, they decided to proceed with a physical campus expansion that would allow them to better serve the students who attended programs at GCR and instructed us to explore this avenue for the expansion. In the new scenario, we aimed to provide a plan to enable SNJ to grow their programming through the addition of classroom space and curriculum, as well as an improved landscape design to match their educational needs. To begin shaping their recommendation, the team conducted background research to understand the history and trends in outdoor environmental education. After gaining in-depth knowledge of the area of interest, further research in the form of case studies and qualitative interviews were conducted with experts from best-in-class outdoor environmental education organizations from the United States and Canada. The results of this primary research included information on how environmental education center leaders utilized their classrooms, planned their expansions, embraced their mission, and implemented their curriculum. Pairing this newly acquired knowledge with our knowledge of SNJ’s needs and resources, we ultimately developed recommendations that included curriculum adjustments, landscape design to enhance environmental education programming, and types of structures that would not only meet their needs, but also help them to embrace their mission. The final recommendations provided by our team will propel the SNJ campus and the on-campus learning experience to the next level of outdoor education, and include 1) the addition of an indoor learning space (classroom) designed as a modular building with sustainability features and 2) a landscape design that includes the addition of physical features that both enhance current curriculum (e.g. forest ecology, pond ecology, water cycle) and also create opportunities for new curriculum (e.g. soil ecology, land forms, sustainability challenge, food cycle). We ultimately provided a design proposal that put SNJ’s mission of environmental education at the forefront. Each aspect of the recommendation puts SNJ’s mission first, offering a best case scenario without monetary or regulatory restrictions. Ultimately, the team was able to apply the perspective of their individual specialties (Landscape Architecture, Sustainable Systems, Behavior, Education and Communication) to provide a sustainability-driven solution to SNJ.Master of Science Master of Landscape ArchitectureNatural Resources and EnvironmentUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/117661/1/Sierra_Nevada_Journeys_MP.pd

Cross-talk of nitric oxide and reactive oxygen species in plant programed cell death

In plants, programed cell death (PCD) is an important mechanism to regulate multiple aspects of growth and development, as well as to remove damaged or infected cells during responses to environmental stresses and pathogen attacks. Under biotic and abiotic stresses, plant cells exhibit a rapid synthesis of nitric oxide (NO) and a parallel accumulation of reactive oxygen species (ROS). Frequently, these responses trigger a PCD process leading to an intrinsic execution of plant cells. The accumulating evidence suggests that both NO and ROS play key roles in PCD. These redox active small molecules can trigger cell death either independently or synergistically. Here we summarize the recent progress on the cross-talk of NO and ROS signals in the hypersensitive response (HR), leaf senescence and other kinds of plant PCD caused by diverse cues

Note on the Persistence of a Nonautonomous Lotka-Volterra Competitive System with Infinite Delay and Feedback Controls

We study a nonautonomous Lotka-Volterra competitive system with infinite delay and feedback controls. We establish a series of criteria under which a part of n-species of the systems is driven to extinction while the remaining part of the species is persistent. Particularly, as a special case, a series of new sufficient conditions on the persistence for all species of system are obtained. Several examples together with their numerical simulations show the feasibility of our main results

306-321 GHz Wideband Channel Measurement and Analysis in an Indoor Lobby

The Terahertz (0.1-10 THz) band has been envisioned as one of the promising spectrum bands to support ultra-broadband sixth-generation (6G) and beyond communications. In this paper, a wideband channel measurement campaign in an indoor lobby at 306-321 GHz is presented. The measurement system consists of a vector network analyzer (VNA)-based channel sounder, and a directional antenna equipped at the receiver to resolve multi-path components (MPCs) in the angular domain. In particular, 21 positions and 3780 channel impulse responses (CIRs) are measured in the lobby, including the line-of-sight (LoS), non-line-of-sight (NLoS) and obstructed-line-of-sight (OLoS) cases. Multi-path propagation is elaborated in terms of clustering results, and the effect of typical scatterers in the indoor lobby scenario in the THz band is explored. Moreover, indoor THz channel characteristics are analyzed in depth. Specifically, best direction and omni-directional path losses are analyzed by invoking close-in and alpha-beta path loss models. The most clusters are observed in the OLoS case, followed by NLoS and then LoS cases. On average, the power dispersion of MPCs is smaller in the LoS case in both temporal and angular domains, compared with the NLoS and OLoS counterparts.Comment: 6 pages, 15 figure

Channel Measurement and Characterization with Modified SAGE Algorithm in an Indoor Corridor at 300 GHz

The much higher frequencies in the Terahertz (THz) band prevent the effective utilization of channel models dedicated for microwave or millimeter-wave frequency bands. In this paper, a measurement campaign is conducted in an indoor corridor scenario at 306-321 GHz with a frequency-domain Vector Network Analyzer (VNA)-based sounder. To realize high-resolution multipath component (MPC) extraction for the direction-scan measurement campaigns in the THz band, a novel modified space-alternating generalized expectation-maximization (SAGE) algorithm is further proposed. Moreover, critical channel characteristics, including the path loss, shadow fading, K-factor, delay spread, angular spreads, cluster parameters, and cross correlations are calculated and analyzed in the LoS case. Besides, two contrasted measurement campaigns in the NLoS case are conducted, with and without additional reflective foils on walls to serve as effective scatterers. Comparison results indicate that the reflective foils are useful to improve the channel conditions in the NLoS case by nearly 6 dB, which is potential to be utilized as alternative of intelligent reflecting surfaces (IRS) to enhance the coverage ability of THz communications.Comment: 12 pages, 8 figure

300 GHz Channel Measurement and Characterization in the Atrium of a Building

With abundant bandwidth resource, the Terahertz band (0.1~THz to 10~THz) is envisioned as a key technology to realize ultra-high data rates in the 6G and beyond mobile communication systems. However, moving to the THz band, existing channel models dedicated for microwave or millimeter-wave bands are ineffective. To fill this research gap, extensive channel measurement campaigns and characterizations are necessary. In this paper, using a frequency-domain Vector Network Analyzer (VNA)-based sounder, a measurement campaign is conducted in the outdoor atrium of a building in 306-321 GHz band. The measured data are further processed to obtain the channel transfer functions (CTFs), parameters of multipath components (MPCs), as well as clustering results. Based on the MPC parameters, the channel characteristics, such as path loss, shadow fading, K-factor, etc., are calculated and analyzed. The extracted channel characteristics and numerology are helpful to study channel modeling and guide system design for THz communications.Comment: 5 pages, 2 figures. arXiv admin note: text overlap with arXiv:2203.16745 by other author