Resource efficient redundancy using quorum-based cycle routing in optical networks

In this paper we propose a cycle redundancy technique that provides optical networks almost fault-tolerant point-to-point and multipoint-to-multipoint communications. The technique more importantly is shown to approximately halve the necessary light-trail resources in the network while maintaining the fault-tolerance and dependability expected from cycle-based routing. For efficiency and distributed control, it is common in distributed systems and algorithms to group nodes into intersecting sets referred to as quorum sets. Optimal communication quorum sets forming optical cycles based on light-trails have been shown to flexibly and efficiently route both point-to-point and multipoint-to-multipoint traffic requests. Commonly cycle routing techniques will use pairs of cycles to achieve both routing and fault-tolerance, which uses substantial resources and creates the potential for underutilization. Instead, we intentionally utilize redundancy within the quorum cycles for fault-tolerance such that almost every point-to-point communication occurs in more than one cycle. The result is a set of cycles with 96.60% - 99.37% fault coverage, while using 42.9% - 47.18% fewer resources.Comment: 17th International Conference on Transparent Optical Networks (ICTON), 5-9 July 2015. arXiv admin note: substantial text overlap with arXiv:1608.05172, arXiv:1608.0516

Unidirectional Quorum-based Cycle Planning for Efficient Resource Utilization and Fault-Tolerance

In this paper, we propose a greedy cycle direction heuristic to improve the generalized $\mathbf{R}$ redundancy quorum cycle technique. When applied using only single cycles rather than the standard paired cycles, the generalized $\mathbf{R}$ redundancy technique has been shown to almost halve the necessary light-trail resources in the network. Our greedy heuristic improves this cycle-based routing technique's fault-tolerance and dependability. For efficiency and distributed control, it is common in distributed systems and algorithms to group nodes into intersecting sets referred to as quorum sets. Optimal communication quorum sets forming optical cycles based on light-trails have been shown to flexibly and efficiently route both point-to-point and multipoint-to-multipoint traffic requests. Commonly cycle routing techniques will use pairs of cycles to achieve both routing and fault-tolerance, which uses substantial resources and creates the potential for underutilization. Instead, we use a single cycle and intentionally utilize $\mathbf{R}$ redundancy within the quorum cycles such that every point-to-point communication pairs occur in at least $\mathbf{R}$ cycles. Without the paired cycles the direction of the quorum cycles becomes critical to the fault tolerance performance. For this we developed a greedy cycle direction heuristic and our single fault network simulations show a reduction of missing pairs by greater than 30%, which translates to significant improvements in fault coverage.Comment: Computer Communication and Networks (ICCCN), 2016 25th International Conference on. arXiv admin note: substantial text overlap with arXiv:1608.05172, arXiv:1608.05168, arXiv:1608.0517

No COVID-19 Climate Silver Lining in the US Power Sector

Recent studies conclude that the global coronavirus (COVID-19) pandemic decreased power sector CO$_2$ emissions globally and in the United States. In this paper, we analyze the statistical significance of CO2 emissions reductions in the U.S. power sector from March through December 2020. We use Gaussian process (GP) regression to assess whether CO2 emissions reductions would have occurred with reasonable probability in the absence of COVID-19 considering uncertainty due to factors unrelated to the pandemic and adjusting for weather, seasonality, and recent emissions trends. We find that monthly CO2 emissions reductions are only statistically significant in April and May 2020 considering hypothesis tests at 5% significance levels. Separately, we consider the potential impact of COVID-19 on coal-fired power plant retirements through 2022. We find that only a small percentage of U.S. coal power plants are at risk of retirement due to a possible COVID-19-related sustained reduction in electricity demand and prices. We observe and anticipate a return to pre-COVID-19 CO2 emissions in the U.S. power sector.Comment: 13 pages, 6 figures, preprin

Venous thromboembolism (VTE) in post-prostatectomy patients

Radical prostatectomy (RP) is one of the recommended treatments to achieve oncological outcomes in localized prostate cancer. However, a radical prostatectomy is a major abdominopelvic surgery. Venous thromboembolism (VTE) is a well-known complication associated with surgical procedures, including RP. There is a lack of consensus regarding VTE prophylaxis in urological procedures. The aim of this systematic review and meta-analysis was to investigate different aspects of VTE in post-radical prostatectomy patients. A comprehensive literature search was performed, and relevant data were extracted. The primary aim was to perform a systematic review and meta-analysis (wherever possible) of VTE occurrence in post-RP patients in relation to surgical approach, pelvic lymph node dissection, and type of prophylaxis (mechanical or combined prophylaxis). The secondary aim was to investigate the incidence and other risk factors of VTE in post-RP patients. A total of 16 studies were included for quantitative analysis. Statistical methods for analysis included the DerSimonian–Laird random effects. We were able to conclude that the overall incidence of VTE in post-radical prostatectomy is 1% (95% CI) and minimally invasive procedures (MIS), including laparoscopic, as well as robotic procedures for radical prostatectomy and RP without pelvic lymph node dissection (PLND), are associated with less risk of developing VTE. Additional pharmacological prophylaxis to mechanical methods may not be necessary in all cases and should be considered in high-risk patients only

Heliophysics Event Knowledgebase for the Solar Dynamics Observatory and Beyond

The immense volume of data generated by the suite of instruments on SDO requires new tools for efficient identifying and accessing data that is most relevant to research investigations. We have developed the Heliophysics Events Knowledgebase (HEK) to fill this need. The HEK system combines automated data mining using feature-detection methods and high-performance visualization systems for data markup. In addition, web services and clients are provided for searching the resulting metadata, reviewing results, and efficiently accessing the data. We review these components and present examples of their use with SDO data.Comment: 17 pages, 4 figure

Anesthesia Duration as an Independent Risk Factor for Early Postoperative Complications in Adults Undergoing Elective ACDF.

Study Design: Retrospective study. Objective: To determine the presence of any potential associations between anesthesia time with postoperative outcome and complications following elective anterior cervical discectomy and fusion (ACDF). Methods: Patients who underwent elective ACDF were identified in the American College of Surgeons National Quality Improvement Program database. Patient demographics, medical comorbidities, and perioperative and postoperative complications up to 30 days were analyzed by univariate and multivariate analysis. Results: A total of 3801 patients undergoing elective ACDF were identified. Patients were subdivided into quintiles of anesthesia time: Group 1, 48 to 129 minutes (n = 761, 20%); Group 2, 129 to 156 minutes (n = 760, 20%); Group 3, 156 to 190 minutes (n = 760, 20%); Group 4, 190 to 245 minutes (n = 760, 20%); and Group 5, 245 to 1025 minutes (n = 760, 20%). Univariate analysis showed significantly higher rates of any complication ( Conclusion: Prolonged anesthesia duration is associated with increased odds of complication, venous thromboembolism, increased length of stay, and return to the operating room

Process Optimisation of Steam Explosion Parameters on Multiple Lignocellulosic Biomass using Taguchi Method:A Critical Appraisal

Xylitol is a low calorie sweetener that can be produced through a bioconversion approach from lignocellulosic biomass that requires pretreatment prior to the bioconversion of xylose to xylitol. Steam explosion (SE) is an industrially scalable pretreatment (PT) process with the potential to liberate xylose monomers, however SE-PT has not been optimised for xylose release from multiple feedstock. The effect of pressure, substrate weight, phosphoric acid loading concentration and residence time on four feedstock (wheat straw (WS), corn stover (CS), Miscanthus (M), and willow (W)) for xylose release and minimal fermentation inhibitor productions (furfural and 5-hydroxymethylfurfural (HMF)) was investigated using the Taguchi methodology for design of experiment (DoE) with variation at four levels (44). An L16 orthogonal array design was utilised and all factors indicated influence on xylose release and inhibitor formation and the resulting xylose rich hydrolysate assessed for bioconversion to xylitol.. The L16 DoE gave hydrolysates containing 75-95% of xylose content in the original biomass, whilst retaining cellulose and lignin components in the fibre. The level of inhibitors were within boundary limits to enable microbial fermentation of the hydrolysates to xylitol. Fine tuning of the overall evaluation criteria (OEC) model imbibing 1.5 kg feedstock in 1.2% w/v orthophosphoric acid, 12 bar(g) and 6 minutes residence time resulted in 90% xylose recovery and production of >1000 L of wheat straw hydrolysate for bioconversion to xylitol. The advantages and limitations of the Taguchi OEC model and further improvements to this process are discussed in a biorefining contextpublishersversionPeer reviewe