microSlotted 1-Persistence Flooding in VANETs

Many Driver Support Systems in future vehicles will rely on wireless communication. This wireless communication can be divided into two categories: Vehicle-to-Vehicle (V2V) and Vehicle-to-Infrastructure (V2I). V2V is often used for vehicles to exchange information of a local nature, e.g. co-operative following or collision avoidance. V2I can be used as ’smart road signs’, access to back-end networks (e.g. Internet) or as simple repeaters. The term VANET is key to V2V and V2I communication: Vehicular Ad hoc Network. A Driver Support System described in [1] presents an interesting problem: a vehicle should be aware of the state of traffic on a road, up to several kilometers ahead. A system called the TraffiFilter has been proposed in [2] to provide this information

Providing over-the-horizon awareness to driver support systems

Vehicle-to-vehicle communications is a promising technique for driver support systems to increase traffic safety and efficiency. A proposed system is the Congestion Assistant [1], which aims at supporting drivers when approaching and driving in a traffic jam. Studies have shown great potential for the Congestion Assistant to reduce the impact of congestion, even at low penetration. However, these studies assumed complete and instantaneous availability of information regarding position and velocity of vehicles ahead. In this paper, we introduce a system where vehicles collaboratively build a so-called TrafficMap, providing over-the-horizon awareness. The idea is that this TrafficMap provides highly compressed information that is both essential and sufficient for the Congestion Assistant to operate. Moreover, this TrafficMap can be built in a distributed way, where only a limited subset of the vehicles have to alter it and/or forward it in the upstream direction. Initial simulation experiments show that our proposed system provides vehicles with a highly compressed view of the traffic ahead with only limited communication

Frame Capture in IEEE 802.11p Vehicular Networks

IEEE 802.11p is the new standard proposed by the IEEE for wireless connectivity in a vehicular context. It can be used by Advanced Driver Assistance Systems (ADAS) and Intelligent Transport Systems (ITS) to make vehicles aware of the traffic around them and increase vehicle safety with applications like cooperative cruise control, assisted merging and assisted lane switching. It is an amendment to the 802.11 standards family, with a physical layer based on Orthogonal Frequency Division Multiplexing (OFDM) similar to 802.11a. It is designed operate in a harsh environment. The increased degree of movement in a vehicular network creates Doppler shift, for example when vehicles connect to roadside units. Also, the cars on the road generate a significantcant amount of scattering and fast fading effects. This Doppler shift and other effects are accounted for in the design of the physical layer of 802.11p

Towards Scalable Beaconing in VANETs

Beaconing is envisioned to build a cooperative awareness in future intelligent vehicles, from which many ITS applications can draw their inputs. The problem of scalability has received ample attention over the past years and is primarily approached using power control methods. We reason power control alone will not be sufficient if we are to meet application requirements; the rate at which beacons are generated must also be controlled. Ultimately, adaptive approaches based on actual channel and traffic state can tune MAC and beaconing properties to optimal values in the dynamic VANET environment

Marine snow formation during oil spills: additional ecotoxicological consequences for the benthic ecosystem

The Deepwater Horizon (DWH) oil spill in the Gulf of Mexico in 2010 was one of the largest oil spills in history. For three months, oil leaked from the Macondo well at 1,500 m depth into the Gulf. As one of the spill responses, an unprecedented amount of dispersants were applied, both at the sea surface and, for the first time ever, directly injected into the wellhead. During the spill, unusually large amounts of marine snow, including Extracellular Polymeric Substances (EPS), were formed. Oil-contaminated marine snow aggregates were formed by aggregation of EPS with suspended solids, phytoplankton cells due to the spring bloom, and the dispersed oil droplets. The marine snow sank through the water column and settled on the ocean floor. This process was named MOSSFA: Marine Oil Snow Sedimentation and Flocculent Accumulation. MOSSFA was an important pathway of transferring oil to the deep-sea, and 14-21% of the total discharged oil is estimated to have settled on the sediment, where it impacted the benthic ecosystem. This thesis focused first on the mechanism of EPS snow formation, and then more in depth on the additional ecotoxicological consequences of marine snow formation during oil spills for the benthic ecosystem. Chapter 2 describes the role of chemical dispersants in the presence of phytoplankton in the formation of EPS, one of the main ingredients of marine snow. Results show that phytoplankton-associated bacteria were responsible for the EPS formation, and the symbiosis between the phytoplankton and its associated bacterial community provided the bacteria with energy to produce the EPS. The microcosm experiment in Chapter 3 investigated the effect of marine snow on oil biodegradation in microcosms without benthic macroinvertebrates. Results showed that marine snow hampers oil biodegradation: the presence of marine snow reduced the depletion of oil alkanes by 40%, most likely due to the high biodegradability of marine snow organics compared to the oil. Biodegradation of marine snow resulted in anaerobic conditions in the top of the sediment layer. This reduced the oil biodegradation. Marine snow thus prolongs the residence time of oil in the benthic ecosystem. The next microcosm experiment, described in Chapter 4, investigated the effects of oil-contaminated marine snow on benthic macroinvertebrates, and the effect of macroinvertebrates on oil biodegradation. Bioturbation by the invertebrates increased the oxygenated top layer of the sediment and partly counterbalanced the inhibition of oil biodegradation due to oxygen consumption by marine snow. Survival of three benthic invertebrate species was reduced by (oil-contaminated) marine snow. Oxygen depletion near the sediment surface seemed to be the main reason for the observed adverse effects of the marine snow. In addition, indications were found that some species used the marine snow as food source, even when it was oil-contaminated. In the last microcosm experiment, described in Chapter 5, two benthic invertebrate species were monitored over a period of 42 days after which new animals were introduced and observed for an additional period of 22 days. Marine snow degradation again resulted in lower dissolved oxygen concentrations in the water column, which inhibited oil biodegradation on the sediment compared to oil in combination with clay. The oxygenated top layer of the sediment disappeared, and recovered after ~20 days. At the end of the experiment, mudsnails from the treatments with oiled marine snow had higher PAH concentrations in their tissues than the animals from the treatments with the same amount of oil in clay only, confirming the use of marine snow as food source. Overall, oil-contaminated marine snow on the ocean sediment can negatively affect benthic ecosystems, and can hamper oil biodegradation and ecosystem recovery. The additional consequences of MOSSFA during oil spills and spill responses should be taken into account in oil spill response planning.</p

Mechanical shock during egg de-adhesion and post-ovulatory ageing contribute to spontaneous autopolyploidy in white sturgeon culture (Acipenser transmontanus)

Spontaneous autopolyploidy, a 1.5x increase in genome size resulting from second polar body retention after fertilization, has been documented in cultured sturgeons, with the proportion of spontaneous autopolyploid progeny ranging widely among maternal families. Sturgeon farms wish to reduce the number of spontaneous autopolyploids because their progeny, when crossed with a normal ploidy parent, exhibit intermediate ploidies, resulting in reproductive abnormalities. However, there is limited knowledge of the causes of the second polar body retention in sturgeon culture. In this study, we report the results of experiments performed from 2015 to 2019 aimed at identifying the sources of spontaneous autopolyploidy in white sturgeon (Acipenser transmontanus) culture. In collaboration with several sturgeon farms, we tested whether post-ovulatory ageing, mechanical shock during egg de-adhesion, and the combined effects of both factors increased spontaneous autopolyploidy. To test the effect of post-ovulatory ageing, eggs were collected from females and either fertilized at the industry normative time (2–5 h post-oviposition) or stored in ovarian fluid at 15 °C for 6–8 h before fertilization. To test the effect of mechanical shock, eggs were collected, fertilized 2–5 h post-oviposition and exposed to either gentle or vigorous mixing during the 60 min de-adhesion treatment. Results from this work reveal that post-ovulatory ageing does increase the incidence of spontaneous autopolyploidy in some females, but overall the proportions produced were low (range 0–15%). Proportions of spontaneous autopolyploids in eggs exposed to vigorous mixing were also variable (1–92%) but significantly higher in 75% of the females when compared to their respective controls or gentle mixing treatments, indicating that mechanical shock during egg de-adhesion is likely the primary cause of spontaneous autopolyploidy. To our knowledge this is the first study to document mechanical shock to eggs during de-adhesion as a cause of abnormal ploidy in cultured fishes. We observed high variability in egg quality among females and a significant relationship between embryo mortality and the incidence of spontaneous autopolyploidy when eggs were exposed to mechanical shock. Repeated spawning of a female that produced a high proportion of spontaneous autopolyploids provided preliminary evidence that genetic background may influence the likelihood that a female's eggs will be prone to second polar body retention when subjected to mechanical shock. Although spontaneous autopolyploidy in sturgeon culture will likely never be eliminated entirely, we provide practical recommendations to sturgeon producers to reduce its incidence in a production setting

Gene editing: Breeding or GMO?

Global regulatory frameworks will soon be challenged by recent scientific developments in methods for generating genetically modified animals, particularly gene editing techniques. It is unclear whether animals produced using such technologies will fall under or outside of the regulations developed for genetically engineered (GE) animals produced using recombinant DNA (rDNA) techniques. Many gene editing applications will result in animals that carry induced mutations in target genes or desirable alleles or sequences that originated in other breeds or individuals from within that species. As such, there will be no rDNA or transgenic construct in the animal, and no novel combination of genetic material that has been altered in a way that could not be achieved by natural mating or techniques used in traditional breeding and selection. The current regulatory approach to GE animals has had a stifling effect on the use of this technology in animal breeding programs, and to date no GE animal has yet been sold for food purposes anywhere in the world. Given the importance of improved genetics to the overall environmental footprint of food production, precluding breeder access to safe innovations for use in genetic improvement programs has a large opportunity cost. If genome editing is going to have an opportunity to impact global animal breeding programs its oversight should ideally be proportional to risk based on the novelty of the trait, consider and evaluate both benefits and risks, and fit for purpose, meaning that the reduction in risk obtained by regulatory oversight is greater than the costs of compliance.Regulatory frameworks for genetically modified animals are concurrently being formulated in many countries in concert with rapidly advancing technologies for creating such animals including gene editing and approaches to generate targeted gene knockouts in livestock species. These new animal breeding techniques result in genetically modified organisms (GMOs) that do not fit the classic definition of “transgenic” or genetically engineered (GE), although they are produced through human intervention using recombinant DNA (rDNA) techniques. Some groups have argued that because these genetic modifications are, for at least part of the procedure, produced outside the organism by people using in vitro techniques this alone should be the trigger for regulation (1). However, this seems to disregard the plethora of in vitro techniques that are commonly utilized in conventional animal breeding programs (2). If risk is the main rationale for regulating genetic modification methods, there does not appear to be a clear rationale for regulating only traits and DNA sequences produced using rDNA techniques. If human intervention using in vitro techniques in breeding programs is the trigger for regulation, this would seem to apply equally to many of the breeding methods used in the production of modern broiler chickens and high-producing milk cows which are clearly genetically modified animals relative to their wild ancestors the jungle fowl and auroch, respectively

A comparison of methods for determining ploidy in white sturgeon (Acipenser transmontanus)

Release of sturgeon with abnormal ploidy into the wild may result in reduced fitness due to lowered fertility in the F2 and subsequent generations. Further, there is evidence that ploidy affects reproductive development and caviar yield. Therefore, the ability to accurately characterize the ploidy of white sturgeon (Acipenser transmontanus)is essential for both commercial and conservation aquaculture. This study compares nuclear volume and whole erythrocyte long-axis lengths obtained using Coulter counter and blood smears, respectively, from captive white sturgeon from populations originating in California and Idaho. We examine which method provides the most accurate, time efficient and cost-effective characterization of ploidy in this species. Results from Coulter counter and blood smears were compared to results from flow cytometry, the gold standard for genome size analysis. Previous work suggests that blood smears can distinguish between 8N (diploid)and 12N (triploid)sturgeon, but further analysis is required to see if this method can also be used to identify 10N fish and to provide robust evidence of its utility in 8N and 12N fish across populations. In this study, we demonstrated that the Coulter counter had 100% agreement with flow cytometry in ploidy assignment, while blood smears vary in their accuracy based on population. Blood smears showed a high degree of overlap in erythrocyte long-axis length between 8N and 10N individuals as well as some overlap between 10N and 12N individuals in the California fish, and a high degree of overlap between 8N and 12N individuals in the Idaho fish. Although blood smears are time-intensive and vary in their ploidy assignment accuracy, they are a low-cost technique and as such may have some utility for caviar farms attempting to identify 12N individuals in a small number of broodstock. By comparing the accuracy, efficiency and cost of these three methods, sturgeon farmers and conservation hatcheries will be able to choose the best method for their needs in determining the ploidy of their fish. We determined that Coulter counter is equally accurate to flow cytometry and is also the most time efficient method for ploidy determination in white sturgeon

Over-the-Horizon Awareness for Advanced Driver Assistance Systems: the TrafficFilter and microSlotted 1-Persistence Flooding

Vehicle-to-vehicle communications (V2V) is a promising technique for Advanced Driver Assistance Systems to increase traffic safety and efficiency. A proposed system is the Congestion Assistant, which supports drivers when approaching and driving in traffic congestion. Studies have shown great potential for such systems to reduce the impact of congestion, even at low penetration. However, these studies assumed complete and instantaneous knowledge regarding position and velocity of vehicles ahead. This paper refines and analyses the TrafficFilter, designed to supply the required information to the Congestion Assistant. Vehicles collaboratively build a so-called TrafficMap, providing over-the-horizon awareness. To this end, an improvement to the Slotted 1-Persistence Flooding called microSlotted 1-Persistence Flooding is proposed and evaluated. In a simulation study the TrafficFilter is found to be a viable system to build over-the-horizon awareness for future Advanced Driver Assistance Systems like the Congestion Assistant, without triggering the phenomenon known as Broadcast Storm

Development of a novel clinical scoring system for on-farm diagnosis of bovine respiratory disease in pre-weaned dairy calves.

Several clinical scoring systems for diagnosis of bovine respiratory disease (BRD) in calves have been proposed. However, such systems were based on subjective judgment, rather than statistical methods, to weight scores. Data from a pair-matched case-control study on a California calf raising facility was used to develop three novel scoring systems to diagnose BRD in preweaned dairy calves. Disease status was assigned using both clinical signs and diagnostic test results for BRD-associated pathogens. Regression coefficients were used to weight score values. The systems presented use nasal and ocular discharge, rectal temperature, ear and head carriage, coughing, and respiratory quality as predictors. The systems developed in this research utilize fewer severity categories of clinical signs, require less calf handling, and had excellent agreement (Kappa &gt; 0.8) when compared to an earlier scoring system. The first scoring system dichotomized all clinical predictors but required inducing a cough. The second scoring system removed induced cough as a clinical abnormality but required distinguishing between three levels of nasal discharge severity. The third system removed induced cough and forced a dichotomized variable for nasal discharge. The first system presented in this study used the following predictors and assigned values: coughing (induced or spontaneous coughing, 2 points), nasal discharge (any discharge, 3 points), ocular discharge (any discharge, 2 points), ear and head carriage (ear droop or head tilt, 5 points), fever (≥39.2°C or 102.5°F, 2 points), and respiratory quality (abnormal respiration, 2 points). Calves were categorized "BRD positive" if their total score was ≥4. This system correctly classified 95.4% cases and 88.6% controls. The second presented system categorized the predictors and assigned weights as follows: coughing (spontaneous only, 2 points), mild nasal discharge (unilateral, serous, or watery discharge, 3 points), moderate to severe nasal discharge (bilateral, cloudy, mucoid, mucopurlent, or copious discharge, 5 points), ocular discharge (any discharge, 1 point), ear and head carriage (ear droop or head tilt, 5 points), fever (≥39.2°C, 2 points), and respiratory quality (abnormal respiration, 2 points). Calves were categorized "BRD positive" if their total score was ≥4. This system correctly classified 89.3% cases and 92.8% controls. The third presented system used the following predictors and scores: coughing (spontaneous only, 2 points), nasal discharge (any, 4 points), ocular discharge (any, 2 points), ear and head carriage (ear droop or head tilt, 5 points), fever (≥39.2°C, 2 points), and respiratory quality (abnormal respiration, 2 points). Calves were categorized "BRD positive" if their total score was ≥5. This system correctly classified 89.4% cases and 90.8% controls. Each of the proposed systems offer few levels of clinical signs and data-based weights for on-farm diagnosis of BRD in dairy calves