246 research outputs found
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Zero to sixty hertz : electrifying the transportation sector and enhancing the reliability of the bulk power system
textA revolution is underway in the energy sector. Traditional approaches for managing a bulk power system are beginning to give way to a "smart grid" world, in which controllers may have bidirectional communications, with engaged users. At the same time a second transformation has been underway and growing in strength, namely the transition from petroleum as a transportation fuel source towards natural gas for large fleet vehicles, and electricity for consumer vehicles. This thesis focuses primarily on the synergy between the "smart grid" and vehicle electrification transitions. Moving the transportation sector to electricity as a fuel source, at least in Texas, has a myriad of benefits: Charging an electric vehicle without significant growth in renewable or lower-emitting SOFC technologies leads to very significant (80% per mile, 58% per neighborhood) reductions in CO₂ emissions, as well as significant reductions in NO[subscript X] (41% per mile, 17% per neighborhood), PM₁₀ (73% / 62%), PM₂.₅ and UFPM (62% / 55%). SO[subscript X] levels rose by 37%, but could be mitigated with controlled EV charging strategies. Vehicle charging strategies also significantly improved the neighborhood's total emissions profile. Adding in distributed energy resources, microgrid generation and intelligent charging, when optimally allocated, can further reduce these emissions. Vehicle charging schemes that respond dynamically to distributed renewable generation can even be thought of as having zero emissions due to the continual balance of PV generation and EV load on the low side of the distribution transformer. This thesis argues that there may be additionally significant societal benefits by shifting vehicle transportation to electricity, likely far in excess of what could be achieved by controlling power plant emissions alone. Based on an analysis of the ERCOT region, this shift would be expected to produce significant cost reductions for overall energy, improve health (due primarily to the relocation of UFPM far away from major population centers), and lower societal costs. Further gains can be considered as electric vehicles are significantly more energy efficient than their ICE counterparts. Also, on a larger scale, it’s generally easier to reduce emissions from hundreds of fixed power plants than millions of moving ICE vehicles.Electrical and Computer Engineerin
North Atlantic air-sea interactions driven by atmospheric and oceanic stochastic forcing in a simple box model
Thesis (M.S.) University of Alaska Fairbanks, 2010"North Atlantic (NA) variability has wide-spread implications locally and globally. This study investigates mechanisms driving NA variability using a simple box model incorporating time evolution of interacting upper ocean temperature anomalies, horizontal (Gyre) and vertical (meridional overturning circulation, or MOC) circulation, driven by surface air temperature, wind, and Labrador Sea temperature forcings. Simulated upper ocean responses to external atmospheric forcing result in solutions with redder spectra than solutions by white noise atmospheric forcing, implying that the ocean acts as a low-pass filter to this external forcing. Simulated ocean dynamic response may be viewed as a response to a cumulative atmospheric forcing over an interval defined by system damping properties. A strong anti-correlation links simulated MOC and Gyre circulation intensity suggesting a mechanism, in which system heat balance is maintained via communication between the dynamic components, (e.g. excess of heat supply from a stronger Gyre circulation would be balanced by lack of heat from a weaker MOC circulation and vise versa). Wind was the dominant forcing for NA upper ocean temperature anomalies and the intensity of MOC and Gyre circulations. Further investigations of NA variability mechanisms are important as they have serious implications on global heat transport"--Leaf iii.1. Introduction -- 1.1. General overview of the North Atlantic Ocean -- 1.2. North Atlantic water masses -- 2. North Atlantic variability -- 2.1. North Atlantic atmospheric variability -- 2.2. North Atlantic oceanic variability -- 2.3. Mechanisms governing North Atlantic atmospheric variability -- 2.4. Mechanisms governing North Atlantic oceanic variability -- 2.5. Global and local impacts of North Atlantic variability -- 3. Model description -- 3.1. Governing equations -- 3.2. External stochastic forcings -- 3.2.1. Original observational time series -- 3.2.2. Stochastic forcing development -- 3.3. Numerical solutions of the governing equations -- 3.4. Model experimental design -- 4. Results of model experiments -- 4.1. Results of wind experiments -- 4.2. Results of SAT experiments -- 4.3. Results of labrador experiment -- 4.4. Results of general experiments -- 5. Conclusions -- 5.1. Summary -- 5.2. Main results and future work -- References -- Appendix A. Box model stability tests -- A.1. Numerical and analytical solutions for "MOC" experiment -- A.2. Numerical and analytical solutions for "Gyre" experiment -- A.3. Numerical and analytical solutions for "Ekman" experiment -- A.4. Numerical and analytical solutions for combined forcings -- Appendix B. Wind experiment -- Appendix C. SAT experiment -- Appendix D. Labrador experiment
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An experimental and analytical method for assessing the integration of electric vehicles into the bulk power system
In recent years, several trends are indicating a move towards a very different bulk power system. Increased integration of renewables, energy storage, synchrophasors, microgrids, Internet of Things devices, and electric vehicles are increasing the complexity of the system. While these changes have the potential to lead to significant reductions in environmental impact and peak demand growth, they also require significantly stronger, granular, and faster-moving controls to ensure reliability and resiliency. Previous research shows that electric vehicles have the potential to significantly reduce global (e.g., CO2), and regional (e.g., particulate) emissions associated with transportation. As fast-responding flexible loads, it was hypothesized that electric vehicles could participate in reliability-centric markets. To study the integration of these vehicles into the bulk power system, this project involved building an experimental charging system for electric vehicles with bulk modeling of the electric grid. This research test bed was developed in Taylor, Texas, to analyze real-world behavior of EVs in response to control signals. The diverse group of participating vehicles provided rapid response between 1/6 and 1/2 second, suggesting a strong capacity for providing grid reliability services. Successful real-world tests of primary frequency response and dispatched load control highlight the scalability of this approach. Vehicle charging patterns (as measured by load ramp and current waveform at peak) were observed to be clustered by vehicle make, indicating predictive value of high-resolution waveform measurement at the beginning of a charging session. Simulation of a network with intermittent renewables shows that inclusion of these rapidly responding EVs can strengthen system stability in normal, black start, and islanded situations. It shows that controlled EV charging can provide reliable means for improved renewables integration. The aggregation of electric vehicle charging can certainly provide fast-responding services that provide frequency support, congestion management, synthetic inertia, and many other useful services of significant value to the reliability of the bulk power systemElectrical and Computer Engineerin
Levamisole tainted cocaine causing severe neutropenia in Alberta and British Columbia
<p>Abstract</p> <p>Background</p> <p>Five cases of severe neutropenia (neutrophil counts < 0.5 per 10<sup>9 </sup>cells/L) associated with exposure to cocaine and levamisole, an antihelimithic agent no longer available in Canada, were identified in Alberta in 2008. Alberta and British Columbia (BC) public health officials issued an advisory and urged health care professionals to report cases to public health. This paper presents the findings of the public health investigations.</p> <p>Methods</p> <p>Cases were identified prospectively through reporting by clinicians and a retrospective review of laboratory and medical examiners data from January 1, 2006 to March 31, 2009. Cases were categorized as confirmed, probable or suspect. Only the confirmed and probable cases are included in this paper.</p> <p>Results</p> <p>We compare cases of severe neutropenia associated with tainted cocaine (NATC) identified in Alberta and BC between January 1, 2008 to March 31, 2009. Of the 42 NATC cases: 23(55%) were from Alberta; 19(45%) were from British Columbia; 57% of these cases reported crack cocaine use (93% of those who identified type of cocaine used); 7% reported using cocaine powder; and the main route of cocaine administration was from smoking (72%). Fifty percent of the NATC cases had multiple episodes of neutropenia associated with cocaine use. Cases typically presented with bacterial/fungal infections and fever. One Alberta NATC case produced anti-neutrophil antibodies, and four were positive for anti-neutrophil cytoplasmic antibody (ANCA). Analysis of two crack pipes and one drug sample obtained from NATC cases confirmed the presence of both cocaine and levamisole. A further 18 cases were identified through the retrospective review of laboratory and medical examiner data in Alberta</p> <p>Interpretation</p> <p>Our findings support a link between neutropenia and levamisole tainted cocaine; particularly from smoking the crack form of cocaine. Some patients may be genetically predisposed to develop levamisole-related neutropenia. Awareness of the differential diagnosis will assist clinicians with case timely detection and appropriate management.</p
Pharmacy study of natural health product adverse reactions (SONAR): a cross-sectional study using active surveillance in community pharmacies to detect adverse events associated with natural health products and assess causality
OBJECTIVES: To investigate the rates and causality of adverse event(s) (AE) associated with natural health product (NHP) use, prescription drug use and concurrent NHP-drug use through active surveillance in community pharmacies. DESIGN: Cross-sectional study of screened patients. SETTING: 10 community pharmacies across Alberta and British Columbia, Canada from 14 January to 30 July 2011. PARTICIPANTS: The participating pharmacy staff screened consecutive patients, or agents of patients, who were dropping or picking up prescription medications.PRIMARY OUTCOME MEASURES: Patients were screened to determine the proportions of them using prescription drugs and/or NHPs, as well as their respective AE rates. All AEs reported by the screened patients who took a NHP, consented to, and were available for, a detailed telephone interview (14%) were adjudicated fully to assess for causality.RESULTS: Over a total of 105 pharmacy weeks and 1118 patients screened, 410 patients reported taking prescription drugs only (36.7%; 95% CI 33.9% to 39.5%), 37 reported taking NHPs only (3.3%; 95% CI 2.4% to 4.5%) and 657 reported taking prescription drugs and NHPs concurrently (58.8%; 95% CI 55.9% to 61.6%). In total, 54 patients reported an AE, representing 1.2% (95% CI 0.51% to 2.9%), 2.7% (95% CI 0.4% to 16.9%) and 7.3% (95% CI 5.6% to 9.6%) of each population, respectively. Compared with patients who reported using prescription drugs, the patients who reported using prescription drugs and NHPs concurrently were 6.4 times more likely to experience an AE (OR; 95% CI 2.52 to 16.17; p<0.001). Combined with data from Ontario, Canada, a national proportion was calculated, which found that 45.4% (95% CI 43.8% to 47.0%) of Canadians who visit community pharmacies take NHPs and prescription drugs concurrently, and of those, 7.4% (95% CI 6.3% to 8.8%) report an AE.CONCLUSIONS: A substantial proportion of community pharmacy patients use prescription drugs and NHPs concurrently; these patients are at a greater risk of experiencing an AE. Active surveillance provides a means of detecting such AEs and collecting high-quality data on which causality assessment can be based
P04.51. Study of natural health product adverse reactions (SONAR): active surveillance in community pharmacies
Study of Natural Health Product Adverse Reactions (SONAR): Active Surveillance of Adverse Events Following Concurrent Natural Health product and Prescription Drug Use in Community Pharmacies
Background: Many consumers use natural health products (NHPs) concurrently with prescription medications. As NHP-related harms are under-reported through passive surveillance, the safety of concurrent NHP-drug use remains unknown. To conduct active surveillance in participating community pharmacies to identify adverse events related to concurrent NHP-prescription drug use. Methodology/Principal Findings: Participating pharmacists asked individuals collecting prescription medications about (i) concurrent NHP/drug use in the previous three months and (ii) experiences of adverse events. If an adverse event was identified and if the patient provided written consent, a research pharmacist conducted a guided telephone interview to gather additional information after obtaining additional verbal consent and documenting so within the interview form. Over a total of 112 pharmacy weeks, 2615 patients were screened, of which 1037 (39.7%; 95% CI: 37.8% to 41.5%) reported concurrent NHP and prescription medication use. A total of 77 patients reported a possible AE (2.94%; 95% CI: 2.4% to 3.7%), which represents 7.4% of those using NHPs and prescription medications concurrently (95%CI: 6.0% to 9.2%). Of 15 patients available for an interview, 4 (26.7%: 95% CI: 4.3% to 49.0%) reported an AE that was determined to be “probably” due to NHP use. Conclusions/Significance: Active surveillance markedly improves identification and reporting of adverse events associated with concurrent NHP-drug use. Although not without challenges, active surveillance is feasible and can generate adverse event data of sufficient quality to allow for meaningful adjudication to assess potential harms
Effects of Deliberate Ingestion of Organophosphate or Paraquat on Brain Stem Auditory-Evoked Potentials
Organophosphate (OP) and paraquat (PQ) ingestion is a serious health problem. A common pathology behind OP or PQ poisoning is the generation of reactive oxygen species (ROS) which is known to cause ototoxicity. The aim of the study was to identify the effects of deliberate ingestion of OP or PQ on brain stem auditory-evoked potentials (BAEPs). Consecutive patients with deliberate self-poisoning with OP or PQ who were admitted to a secondary and a tertiary care hospital in the Southern province of Sri Lanka and matched controls were recruited. BAEPs were performed at 1 week (first assessment) and 6 weeks (second assessment) after the exposure. Interpeak latencies of I–III, III–V, and I–V were measured. There were 70 and 28 patients in the OP and PQ arms with the mean age of 32 ± 12 and 29 ± 12 years, respectively. There were 70 controls and their mean age was 33 ± 12 years. In OP and PQ poisoning, 53/70 and 18/28 came for the second assessment, respectively. The interpeak latency was not statistically different in the controls vs the first assessment, controls vs the second assessment, and the first vs the second assessment. There were no significant lesions in the auditory pathway in OP or PQ poisoned patients. The generation of ROS within the perilymphatic space following the ingestion of OP or PQ may not be sufficient to cause lesions in the auditory pathway. Further studies with the assessment of auditory threshold are needed
Noise Correlations Have Little Influence on the Coding of Selective Attention in Area V1
Neurons in the visual primary cortex (area V1) do not only code simple features but also whether image elements are attended or not. These attentional signals are weaker than the feature-selective responses, and their reliability may therefore be limited by the noisiness of neuronal responses. Here we show that it is possible to decode the locus of attention on a single trial from the activity of a small population of neurons in area V1. Previous studies suggested that correlations between the activities of neurons that are part of a population limit the information gain, but here we report that the impact of these noise correlations depends on the relative position of the neurons' receptive fields. Correlations reduce the benefit of pooling neuronal responses evoked by the same object but actually enhance the advantage of pooling responses evoked by different objects. These opposing effects cancelled each other at the population level, so that the net effect of the noise correlations was negligible and attention could be decoded reliably. Our results suggest that noise correlations are caused by large-scale fluctuations in cortical excitability, which can be removed by a comparison of the response strengths evoked by different objects
Auditory brain-stem evoked potentials in cat after kainic acid induced neuronal loss. I. Superior olivary complex
Auditory brain-stem potentials (ABRs) were studied in cats for up to 45 days after kainic acid had been injected unilaterally or bilaterally into the superior olivary complex (SOC) to produce neuronal destruction while sparing fibers of passage and the terminals of axons of extrinsic origin connecting to SOC neurons. The components of the ABR in cat were labeled by their polarity at the vertex (P, for positive) and their order of appearance (the arabic numerals 1, 2, etc.). Component P1 can be further subdivided into 2 subcomponents labeled P1a and P1b. The correspondences we have assumed between the ABR components in cat and man are indicated by providing a Roman numeral designation for the human component in parentheses following the feline notation, e.g., P4 (V). With bilateral SOC destruction, there was a significant and marked attenuation of waves P2 (III), P3 (IV), P4 (V), P5 (VI), and the sustained potential shift (SPS) amounting to as much as 80% of preoperative values. Following unilateral SOC destruction the attenuation of many of these same ABR components, in response to stimulation of either ear, was up to 50%. No component of the ABR was totally abolished even when the SOC was lesioned 100% bilaterally. In unilaterally lesioned cats with extensive neuronal loss (greater than 75%) the latencies of the components beginning at P3 (IV) were delayed to stimulation of the ear ipsilateral to the injection site but not to stimulation of the ear contralateral to the injection. Binaural interaction components of the ABR were affected in proportion to the attenuation of the ABR. These results are compatible with multiple brain regions contributing to the generation of the components of the ABR beginning with P2 (III) and that components P3 (IV), P4 (V), and P5 (VI) and the sustained potential shift depend particularly on the integrity of the neurons of the SOC bilaterally. The neurons of the lateral subdivision (LSO) and the medial nucleus of the trapezoid body (MNTB) of the SOC have a major role in generating waves P3 (IV) and P4 (V)
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