Cascade Delays Research Articles

Cascading Delays for the High-Speed Rail Network Under Different Emergencies: A Double Layer Network Approach

High-speed rail (HSR) has formed a networked operational scale in China. Any internal or external disturbance may deviate trains' operation from the planned schedules, resulting in primary delays or even cascading delays on a network scale. Studying the delay propagation mechanism could help to improve the timetable resilience in the planning stage and realize cooperative rescheduling for dispatchers. To quickly and effectively predict the spatial-temporal range of cascading delays, this paper proposes a max-plus algebra based delay propagation model considering trains' operation strategy and the systems' constraints. A double-layer network based breadth-first search algorithm based on the constraint network and the timetable network is further proposed to solve the delay propagation process for different kinds of emergencies. The proposed model could deal with the delay propagation problem when emergencies occur in sections or stations and is suitable for static emergencies and dynamic emergencies. Case studies show that the proposed algorithm can significantly improve the computational efficiency of the large-scale HSR network. Moreover, the real operational data of China HSR is adopted to verify the proposed model, and the results show that the cascading delays can be timely and accurately inferred, and the delay propagation characteristics under three kinds of emergencies are unfolded.

Cascading Delays in the Monsoon Rice Growing Season and Postmonsoon Agricultural Fires Likely Exacerbate Air Pollution in North India

AbstractOver the past two decades, smoke aerosols from crop residue burning have increasingly degraded postmonsoon (October‐November) air quality in north India. We use satellite data and atmospheric modeling to investigate whether cascading delays in monsoon rice growth and postmonsoon fires over 2003–2019 have exacerbated the already poor urban air quality downwind of the fires. Beginning in 2008, a government effort to combat groundwater depletion in Punjab mandated rice sowing until closer to the arrival of monsoon rains. We find evidence of district‐level delays in the timing of both monsoon rice growth and postmonsoon fires, which vary from 1 to 4 weeks with largely an east‐west gradient. These delays are correlated spatially (r = 0.51–0.77), with northern and western districts in Punjab, which rely less on groundwater for irrigation, tending to have the greatest delays. Had the delays in fire activity not occurred, we estimate that cities downwind and near the fire source would have consistently seen less smoke‐related fine particulate matter (PM2.5), on average ranging from 11% to 21% for New Delhi, Bathinda, and Jind during 2008–2019. This net benefit of earlier postmonsoon burning could have been even larger given that (a) a longer rice‐to‐wheat transition could incentivize farmers to find alternatives to burning crop residues; and (b) background PM2.5 is less abundant earlier in the season, decreasing the likelihood of extreme pollution episodes. Strategies aiming to mitigate air pollution while conserving groundwater may be more effective by promoting an earlier monsoon growing season in districts with less groundwater depletion.

Effect of COVID-19 lockdown on the pathway of care and treatment outcome among patients with tuberculosis in a rural part of northern India: a community-based study

Objectives: The coronavirus disease 2019 (COVID-19) pandemic affected routine healthcare services across all spectra, and tuberculosis (TB) care under the National Tuberculosis Elimination Program have been affected the most. However, evidence available at the community level is minimal. The clinical features, care cascade pathway, and treatment outcomes of TB patients pre- and during/post-COVID-19 pandemic lockdown in a rural community health block in northern India were assessed and compared.Materials and Methods: This was a retrospective cohort study that included all patients diagnosed with TB and initiated treatment under programmatic settings between January 1 and June 30, 2020, in a rural TB unit in northern India. The periods from January 1 to March 23 and March 24 to June 30 were marked as pre-lockdown and during/post-lockdown, respectively.Results: A total of 103 patients were diagnosed and treated for TB during the study period. A significantly higher proportion of pulmonary TB cases were reported during/post-lockdown (43, 82.7%) compared to that pre-lockdown (32, 62.7%), and a higher diagnostic delay was noted during/post-lockdown (35, 81.4%). Through adjusted analysis, patients diagnosed during/post-lockdown period (adjusted risk ratio [aRR], 0.85; 95% confidence interval [CI], 0.73–0.98) and previously treated (aRR, 0.77; 95% CI, 0.60–0.995) had significantly lower favorable treatment outcomes.Conclusions: The symptom and disease (pulmonary/extrapulmonary) pattern have changed during/post-lockdown. The care cascade delays are still high among TB patients, irrespective of the lockdown status. Lockdown had a significant adverse impact on the outcomes of TB treatment.

Experimental investigation of the turbulent cascade development by injection of single large-scale Fourier modes

The current work presents an experimental investigation of the dynamic interactions between flow scales caused by repeated actions of the nonlinear term of the Navier-Stokes equation. Injecting a narrow band oscillation, representing a single Fourier mode, into a round jet flow allows the measurement of the downstream generation and development of higher harmonic spectral components and to measure when these components are eventually absorbed into fully developed turbulence. Furthermore, the dynamic evolution of the measured power spectra observed corresponds well to the measured cascaded delays reported by others. Closely matching spectral development and cascade delays have also been derived directly from a one-dimensional solution of the Navier-Stokes equation described in a companion paper. The results in the current work provide vital information about how initial conditions influence development of the shape of the spectrum and about the extent of the time scales in the triad interaction process, which should be of significance to turbulence modelers.

Wound Healing and the Use of Medicinal Plants.

Cutaneous wound healing is the process by which skin repairs itself. It is generally accepted that cutaneous wound healing can be divided into 4 phases: haemostasis, inflammation, proliferation, and remodelling. In humans, keratinocytes re-form a functional epidermis (reepithelialization) as rapidly as possible, closing the wound and reestablishing tissue homeostasis. Dermal fibroblasts migrate into the wound bed and proliferate, creating “granulation tissue” rich in extracellular matrix proteins and supporting the growth of new blood vessels. Ultimately, this is remodelled over an extended period, returning the injured tissue to a state similar to that before injury. Dysregulation in any phase of the wound healing cascade delays healing and may result in various skin pathologies, including nonhealing, or chronic ulceration. Indigenous and traditional medicines make extensive use of natural products and derivatives of natural products and provide more than half of all medicines consumed today throughout the world. Recognising the important role traditional medicine continues to play, we have undertaken an extensive survey of literature reporting the use of medical plants and plant-based products for cutaneous wounds. We describe the active ingredients, bioactivities, clinical uses, formulations, methods of preparation, and clinical value of 36 medical plant species. Several species stand out, including Centella asiatica, Curcuma longa, and Paeonia suffruticosa, which are popular wound healing products used by several cultures and ethnic groups. The popularity and evidence of continued use clearly indicates that there are still lessons to be learned from traditional practices. Hidden in the myriad of natural products and derivatives from natural products are undescribed reagents, unexplored combinations, and adjunct compounds that could have a place in the contemporary therapeutic inventory.

Posterior Cingulate Cascading Delay Model for Timing Behavior

We present a novel model for timing behavior. This model is based on the firing property of neurons in the superficial layers of the posterior cingulate granular retrosplenial cortex (GRS) and does not require a unit-time clock. Suppose that event B occurs N seconds after event A and triggers behavior C. By our behavioral, physiological and anatomical experiments, we found the following facts. 1) Thalamic input carrying sensory information, A, is provided to the superficial layers of the GRS and delayed by the lateral cascading connection within the layers. 2) Hippocampal input (recall information, B) is provided to the deep layers of the GRS. 3) The GRS neurons show timing behavior that is dependent on the trial cycle. 4) Lesioning the GRS impaired the acquisition of trace fear memory and the production of fear-induced freezing behavior, C. Thus we would propose that neural circuits in the GRS play a crucial role in the animal behaviors requiring time discrimination. The question of whether Hebbian learning occurs at the convergent neurons that integrates thalamic and hippocampal information remains unanswered.

Control and optimization algorithms for air transportation systems

Modern air transportation systems are complex cyber-physical networks that are critical to global travel and commerce. As the demand for air transport has grown, so have congestion, flight delays, and the resultant environmental impacts. With further growth in demand expected, we need new control techniques, and perhaps even redesign of some parts of the system, in order to prevent cascading delays and excessive pollution.In this survey, we consider examples of how we can develop control and optimization algorithms for air transportation systems that are grounded in real-world data, implement them, and test them in both simulations and in field trials. These algorithms help us address several challenges, including resource allocation with multiple stakeholders, robustness in the presence of operational uncertainties, and developing decision-support tools that account for human operators and their behavior.

Canonical Wnt signaling in the oligodendroglial lineage--puzzles remain.

The straightforward concept that accentuated Wnt signaling via the Wnt-receptor-β-catenin-TCF/LEF cascade (also termed canonical Wnt signaling or Wnt/β-catenin signaling) delays or blocks oligodendrocyte differentiation is very appealing. According to this concept, canonical Wnt signaling is responsible for remyelination failure in multiple sclerosis and for persistent hypomyelination in periventricular leukomalacia. This has given rise to the hope that pharmacologically inhibiting this signaling will be of therapeutic potential in these disabling neurological disorders. But current studies suggest that Wnt/β-catenin signaling plays distinct roles in oligodendrogenesis, oligodendrocyte differentiation, and myelination in a context-dependent manner (central nervous system regions, developmental stages), and that Wnt/β-catenin signaling interplays with, and is subjected to regulation by, other central nervous system factors and signaling pathways. On this basis, we propose the more nuanced concept that endogenous Wnt/β-catenin activity is delicately and temporally regulated to ensure the seamless development of oligodendroglial lineage cells in different contexts. In this review, we discuss the role Wnt/β-catenin signaling in oligodendrocyte development, focusing on the interpretation of disparate results, and highlighting areas where important questions remain to be answered about oligodendroglial lineage Wnt/β-catenin signaling.

A new stability result for nonlinear cascade time-delay system and its application in chaos control

Based on the converse Lyapunov stability theorem and invariant set theory, this paper presents a new theorem for the nonlinear cascade delay system. With this new proposed method, a lot of coupled items can be taken as zero items. So the whole system can be converted to a very simple form. Also, a simple chaos control technique is proposed for the uncertain time-delay Lorenz chaotic system via this new method. The controller designed is linear and easy to be implemented. Simulation results for uncertain chaotic systems are provided to illustrate the effectiveness of the proposed scheme.

Action Research: Description of Perceptions and Attitudes toward Cafeteria Rules and Their Effects on Consistent Adherence

Reason: Lunchroom population density and limited opportunity to provide lunch services require a high rate of throughput; even minor disruptions create a cascade delays resulting in insufficient time for student nourishment, or infringement upon academic instruction time. Action research helps educators identify problems, formulate questions, collect and analyze data, then develop plans of action. Problem: This study describes perceptions and attitudes toward the cafeteria rules that may contribute to or detract from consistent adherence. It seeks to answer the following questions: What are students’ and adults’ perceptions of the rules, rule compliance, and impact of compliance/non-compliance? How do the perceptions of students, monitors, and intervening supervisors compare and contrast? Methodology: This is a non-randomized, cross-sectional, mixed methods sequential assessment of perceptions and attitudes toward published behavior rules for the cafeteria. A convenience sample of three data sources: students, lunchroom monitors, and intervening support staff (adults) were data sources. Quantitative data collection was followed by qualitative data collection from interviews with key intervening supervisory staff. Results: The questionnaire response rate for students (n=78) was 86.5%, and for adults (n=16) was 84.4%. Statistically significant differences between students and adults in perception of rule utility and adherence were observed. Interviews of seven intervening supervisory adults were obtained to explore strategies for closing perception gaps. Implications: Results indicate adults hold high expectations that students may not perceive themselves capable of meeting. Interview provided triangulation to strengthen analysis of findings, and suggest strategies for designing intervention to increase future compliance.

Multi-level Shunt Active Power Filter Using Modular Cascade H-bridge and Delay Firing

A novel design of a multi-level shunt active power filter using a modular cascade H-bridge is presented in this article. The proposed approach enables a modular approach in the design of a multi-level active power filter. As an illustration, a five-level H-bridge active power filter with a novel switching strategy has been implemented. The design is able to reduce the voltage stress across the filter inductor and to reduce the average switching frequency. Proportional plus integral controllers have been implemented for the current control loop, overall voltage control loop, and voltage balancing loop. A feedforward controller has also been added to the current control loop to improve the current tracking. By delaying the firing time of one of the H-bridges, five levels can be realized from a cascade H-bridge active power filter. The proposed switching strategy and the realization of the five-level switching scheme are presented. Experimental results are included to demonstrate the effectiveness of the proposed filter scheme.

Secure Interchange Routing

Locations that connect tracks from different rail-road companies—referred to as interchange points—ex- change crew, locomotives, and their associated consists. Because trains have a single degree of freedom in movement, that is, they can only operate along the tracks, any delay occurring at an interchange point causes cascading delays in connecting tracks. In addition, authentication and authorization that is expected to take place at interchanges in PTC controlled train movement may add extra delays due to mutual authentication between two security domains. In this paper we propose a model that can address safety and security con- cerns and their interrelationships that govern train movement through an interchange point. We show how a profile of safe operations can be computed for operating an interchange point.

A fuzzy logic model for competitive assessment of airline service quality

The purpose of this paper is to develop an operational performance model with direct applicability to the post-9/11 US airline industry. The premise is to come as close as possible to ideal performance goals for five operational parameters i.e., on-time arrival, turnaround time, cascade delay percentage, taxi-out time, and taxi in time, based on length of haul. Since airline-operating performance depends upon several factors that cannot be described in crisp terms, these data fit within fuzzy logic set descriptors and theory. A database of numerical scores is transformed into a fuzzy database, and then fuzzy probabilities are used to assess the belief that the scores fall within the desired range for each criterion. Industry data are used to compare individual airline carrier performance measurements to anticipated industry operational goals. Application potential for the model is not restricted, however, to this industry.

Disruption of the complement cascade delays retinal ganglion cell death following retinal ischemia-reperfusion

Recent reports have indicated that components of the complement cascade are synthesized during the degeneration of retinal ganglion cells (RGC) in glaucoma. While complement deposition in the retina may simply serve to aid phagocytosis of damaged RGC, activation of the complement cascade can also contribute to neuronal loss in neurodegenerative diseases. This study was designed to determine if disruption of the complement cascade affects RGC survival in a murine model of retinal ischemia-reperfusion (I/R) injury. We induced retinal ischemia in the eyes of normal mice and mice with a targeted disruption of the complement component 3 (C3) gene. Tissue was harvested 7 and 21 days after induction of I/R and retinal complement synthesis was determined by quantitative PCR and immunohistochemical methods. RGC death and associated axon loss was evaluated through histological examination of the optic nerve and retina. Our data show that retinal I/R induces the expression and deposition of complement components. C3 deficient mice clearly exhibited reduced optic nerve damage and substantial preservation of RGC 1 week after I/R when compared to normal animals ( p = 0.005). Three weeks after the ischemic event C3 deficient mice retained more RGC cell bodies although the degree of optic nerve damage was similar between both groups. These findings demonstrate that inhibition of the complement cascade delays optic nerve axonal and RGC degeneration in retinal I/R. It appears that injured RGC are targeted and actively destroyed through complement mediated processes. These results may have implications for the pathophysiology and clinical management of ischemic retinal conditions.

Cascading delay line time-to-digital converter with 75 ps resolution and a reduced number of delay cells

A time-to-digital converter (TDC) is described, integrated on a single field-programmable gate array device with 75 ps single-shot resolution (LSB). Multiple-shot measurement statistically improves resolution to about 5 ps. The circuit is based on a counter and a two-step cascading delay line method that uses only 24 delay cells to provide 128 LSBs in the interpolator that resolves the time interval within the reference clock cycle. The relevant calibration method is also presented to obtain the time parameters of the TDC at the current temperature and voltage. This TDC can measure time intervals from 0 to 1.3 ms and the maximum range is only limited by the range of the counter. The temperature dependence is 0.1 ps/°C.

Maximizing Operating Reliability in Design of Long Single-Track Light Rail Transit Lines

At 79 km, the proposed Southeastern Pennsylvania Transportation Authority Cross County Metro would be the longest light rail transit (LRT) line in North America. The system would use an existing single track constructed on embankment, and adding a second LRT track over the entire distance would be prohibitively expensive. However, operating a single-track line of this length at 15-min headways would pose an unprecedented operational challenge using conventional approaches to siding location. The longer the line, the greater the likelihood that a late train will delay opposing trains and cause further delays. A methodology for locating passing sidings on single-track lines to mitigate the problem of cascading delays, even on long lines, is proposed. Unlike the conventional practice of locating sidings at the midpoint of scheduled meets, the sidings near the outer ends of the line are located off-center relative to the meet point, and are longer than those in the middle of the line. This tailors the length of siding cushion on either side of the meet point to match the risk of delay, and maximizes the effectiveness of the full length of each siding. Simulation results indicate that long single-track lines can be designed successfully to avoid delay propagation. However, the siding location methodology leaves little room for compromise. In addition, the resulting sidings are forever wedded to a specific operating plan. Station stopping patterns and operating speed cannot be changed once the sidings are in place, with headways only in multiples of the design headway.

Initial bremsstrahlung conversion

Electromagnetic cascades arising from a primary electron pair have been studied in emulsions exposed to 300-GeV protons, and also in emulsions exposed to 200-GeV negative pions. Cascade development is examined through the occurrence of initial bremsstrahlung conversion along some hundreds of primary-pair-member tracks of path length > 10 mm and energy > 3 GeV. Cascades associated with pion-nucleus collisions evidently develop in accord with theory, while those from proton-nucleus collisions show cascading delay \ensuremath{\sim}${10}^{\ensuremath{-}11}$ sec. A check on cascades generated by 400-GeV proton-nucleus collisions also shows this delayed cascading. After close consideration of error sources, an explanation is sought in assumptions about the electromagnetic field.