Demand Pressure Research Articles

Workload Measurement Using the Cardiovascular Load Method and Defense Research Agency Workload Scale

Workload is a collection of tasks set to be completed within a specific time. The workload can be broken down into "qualitative" (too much or too little) or "quantitative" (too much or too little), which occurs when people are unable to complete tasks or if they do not utilize the abilities they have in achieving a particular job. This study aimed to determine the workload of workers engaged in the sale of fresh or cut chicken meat. Cardiovascular Load is an estimate to determine the classification of workload based on the increase in work pulse compared to the maximum heart rate. The Defense Research Agency Workload Scale (DRAWS) method is a multidimensional technique that involves participants through subjective questions and assessments consisting of four workload dimensions: input demand, central demand, output demand, and time pressure. The results showed that the workload pulse using Cardiovascular Load, the level of fatigue based on workload obtained at the chicken slaughter station by worker 1 was 44.77%, and worker 2 was 41.11% with the category of improvement needed. At the chicken cleaning station, worker 1 was 44.13%, and worker 2 was 47.43%, with the category of needed improvement. At the chicken cutting station, worker 1 was 43.73%, and worker 2 was 45.85%, with the category of needed improvement. The study's DRAWS method results showed that at the chicken slaughtering station, worker 1 was 84.25%, and worker 2 was 87.05% with the overload category. At the chicken cleaning station, worker 1 was 86.75%, and worker 2 was 84.20% with the overload category. At the chicken cutting station, worker 1 was 85.75%, and worker 2 was 81.30%, with the overload category. This means that six respondents felt a high mental burden, so improvements are needed to reduce the impact of the cognitive workload of workers. The upgrades provided include the provision of chairs around the work area, especially at the chicken slaughtering station, so that workers can sit and rest for a moment to reduce the physical workload experienced by workers.

Optimization of an Urban Microgreen Space Distribution Based on the PS-ACO Algorithm: A Case Study of Shenyang, China

In this study, optimization of the microgreen space distribution through multistage regulation is investigated, with the goal of alleviating the imbalance between the supply and demand of green resources in the central urban area of Shenyang. An optimized evaluation model of green space supply and demand is employed to calculate the green space accessibility index at a 100-m grid scale and identify different levels of green space resource supply and demand. Priority is given to supplementing resources for the elderly population by balancing the green space supply in vulnerable areas. Particle swarm—ant colony optimization (PS-ACO) is used to select microgreen space sites within each priority level. On the basis of the “important-urgent” quadrant analysis, S1-priority residential areas account for 8.12% of the grid, S2-priority areas account for 67.01%, and S3-priority areas account for 24.87%. The PS-ACO algorithm outputs potential microgreen space sites within each priority level to accurately regulate the green space distribution in residential areas with different supply pressures and limited land availability. A spatial correlation analysis of the new sites reveals good spatial dispersion within service units, effectively alleviating demand pressures, and good aggregation at a regional scale to address imbalances in the supply of green space in a targeted manner. Thus, the optimized results of the PS-ACO algorithm are effective, providing reliable site-selection references for subsequent urban microgreen space distributions.

Synthesis and characterization of natural rosin-modified silica nanocomposite and its green multifunctional applications for drilling fluid

The increasing energy demand and environmental pressure require the utilization of high-performance and eco-friendly drilling fluid materials for oil/gas exploration. Herein, a green nanocomposite involving the core structure of silica (SiO2), the resin shell structure of rosin dehydroabietic acid (DHAA) derivative [poly(DHAA-co-styrene) (PDS)], and the crown structure of hydrophilic layer [crosslinked poly(2-acrylamido-2-methyl-1-propanesulfonic acid-co-N, N-dimethylacrylamide) (CAD)] was prepared through semi-continuous emulsion polymerization and utilized as a high-performance and multifunctional additive for drilling fluid. The optimal composition of core, shell and crown was determined to be 0.3: 10: 2 in mass, and the DHAA component accounted for 50 wt% in the shell structure and the molar ratio of 2-acrylamido-2-methyl-1-propanesulfonic acid and N, N-dimethylacrylamide in the crown was 3:7. The core-shell-crown nanocomposite (SiO2-PDS-CAD) exhibited a well-organized multi-layered nanostructure with an effective encapsulation of PDS on nano-SiO2 and CAD on PDS, facilitating a uniform nano-dispersion of SiO2-PDS-CAD. The bulky copolymerized rosin-based segments coupled with nano-SiO2 resulted in high thermal stability of SiO2-PDS-CAD and broadened the softening point of raw rosin from 87°C to 141°C. Meanwhile, the environmental assessments of acute toxicity and biodegradability showed that SiO2-PDS-CAD was nontoxic and readily biodegradable, and the higher incorporation of rosin components enabled SiO2-PDS-CAD more biodegradable in contrast to the non-biodegradability of the analog without rosin. Moreover, SiO2-PDS-CAD showed versatile functions in bentonite-based drilling fluid by maintaining high yield points, lowering fluid loss and enhancing nano-porous plugging capacity (100–400 nm), especially at elevated temperatures (140–180°C). A maximum increment of 1200 % on yield point occurred after aging 170°C, and the highest improvement of approximately 72 %-75 % on fluid loss occurred at 150–180°C. It also could effectively inhibit clay swelling and decrease the lubrication coefficient. The enhancement mechanism was revealed to be the core-shell-crown synergistic effects, in which the hydrophilic crown contributed to the dispersion stability of SiO2-PDS-CAD and affinity with bentonite clay, and the rigid bridging of core and flexible deformation of rosin shell strengthened the interparticle interactions. The study highlighted a novel strategy for preparing high-value-added rosin-based biomass material for green multifunctional applications in water-based drilling fluids.

How does trauma secondary to unexpected extreme weather affect orthopaedic surgery departments? : An epidemiological study on the Filomena snowstorm

Trauma secondary to extreme weather events may heavily impact the normal activity of orthopaedic surgery departments, especially in places not prepared to deal with them. The Filomena snowstorm, which happened in January 2021, was one of the greatest snowstorms ever in Spain. During it, the constant influx of trauma patients caused Orthopaedic Emergencies Department (OED) to collapse. The primary objective of this study was to describe the orthopaedic injuries and changes in fracture's epidemiology observed during this exceptional period. Secondary objectives were to analyse the collected variables in order to minimize the future impact of these unexpected extreme weather events. A retrospective cohort study between patients that came to the OED during the snowstorm (Filomena group) and those who came on the same period of the previous year (Control group) was made. The following data were collected: age, sex, injury location, injury mechanism, diagnosis, AO/OTA fracture classification, treatment type (conservative vs surgical) and delay of surgical treatment. Atotal of 1237 patients were included, 655 patients from the Filomena group and 582 from the Control group. One in two patients in the Filomena group sustained afracture (50.7% vs 23.2%). The most frequent diagnosis on the Filomena group was distal radius fracture (16.2%), which was five times more frequent than in the Control group (3.4%). Asignificant increment was also observed in the incidence of ankle (21.7%) and proximal humerus (33%) fractures. In the Filomena group, surgically treated fractures increased by 168%, being more severe, as C‑type fractures were more prevalent (23% vs 13%). Mean delay to surgery was 6.78 days during the snowstorm. Unexpected snowstorms entail an exponential rise in orthopaedic care demand and OED pressures. Asignificant increment in orthopaedic trauma surgery, up to 168% more, particularly distal radius, proximal humerus and ankle fractures, is to be expected, which will imply elective surgery cancellation, hurting patients and increasing costs.

A hierarchical solution framework for dynamic and conflict-free AGV scheduling in an automated container terminal

Container terminals worldwide are experiencing their transitions into automated and intelligent terminals in the face of the ever increasing container handling demand and cost pressure. A key to cost-effective operations in automated container terminals is the efficient AGV scheduling algorithm that enables on-time fulfillment of container loading and discharging tasks. In this paper, we study an integrated task assignment and path planning problem for AGV scheduling in an automated container terminal. We propose a hierarchical solution framework to empower dynamic AGV scheduling, where the higher level employs a reinforcement learning algorithm for dynamic task assignment and the lower level makes use of a tailored path generation algorithm to generate low-cost and conflict-free paths for AGVs to serve the tasks. Additionally, we propose a container matching heuristic and a two-layer grid map to enhance the learning ability of the reinforcement learning algorithm. We compare the performance of the hierarchical solution framework against various benchmark methods on problem instances of practical scales. The results show that our approach is effective in reducing task delays and mitigating path conflicts, making the task assignment and path planning decisions more applicable for AGV scheduling in an automated container terminal.

Current State and Future Potential of Energy Efficiency and Demand Side Management in the South African Context

This paper explores the current state and future potential of Energy Efficiency and Demand Side Management (EEDSM) in South Africa. With a heavy reliance on coal for electricity generation, South Africa faces significant environmental and sustainability challenges. Integrating renewable energy sources like wind, water, and solar (WWS) is crucial for reducing greenhouse gas emissions and ensuring energy security. The study highlights the importance of demand-side management in optimising energy consumption and mitigating peak demand pressures. The South African government has implemented various policies and regulatory frameworks to promote EEDSM, focusing on reducing energy consumption through technological innovations and strategic planning. Models such as the Five-Stage Model for Computer Technology Integration, the E-Capacity Model, and the Systemic Planning Model for ICT Integration provide structured approaches to integrating advanced technologies and practices into energy systems. The research includes a comprehensive analysis of South Africa's current energy mix, predominantly coal and nuclear, and projects a shift towards a diversified portfolio dominated by renewable sources by 2050. This transition is expected to create substantial employment opportunities and enhance energy efficiency. Case studies and success stories from both the public and private sectors underscore the economic and environmental benefits of EEDSM initiatives. South Africa can significantly improve its energy efficiency and sustainability by leveraging innovative energy technologies, such as smart grids and smart metering. The findings emphasise the need for continued investment in renewable energy and demand- side management to achieve a more resilient and efficient energy sector.

Methodological proposal to determine explosive tourism growth: a warning for unsustainable development?

ABSTRACT Sustainability is a crucial aspect of tourism growth and development. This paper suggests the adaptation of a methodology originally designed for analysing explosive behaviour in financial market time series to assess the explosive behaviour of demand pressure in tourist destinations. The proposed methodology could function as an early warning system for potential issues such as over-tourism by identifying further unsustainable growth in destinations. The methodology is exemplified by examining the long-term evolution of tourism pressure in both Spain as a whole, and in Barcelona, which is a destination frequently scrutinised in the literature and media due to perceived over-tourism. The findings suggest explosive behaviour in tourism pressure, especially in the case of Barcelona, from which valuable lessons can be learned and meaningful conclusions drawn.

A comprehensive framework for targeting the disturbance propagation path and debottleneck strategy of chemical process considering the topology and cascading effects

For the chemical processes, multiple fluctuations exist, and elucidating the system's dynamic changes is essential in improving its adaptability. With changes in reactor and separator operating conditions and cascading effects related to the system's topological structure considered, a comprehensive framework is established to target the disturbance propagation path and determine cost-effective debottlenecking strategies. Relations among distillation column parameters and the seasonal change in ambient temperature are deduced considering meteorological data, and the utility demand or column pressure under various conditions can be determined. All independent subsystems of the heat exchanger network and their heat surplus/deficit are identified based on the improved information flow diagram and output difference analysis, and the disturbance propagation path is determined. Correlations are deduced to clarify the heat transfer capacity requirement under fluctuating states, and the bottlenecks and cost-effective debottlenecking strategy without topology modification are identified at different stages. The proposed method is intuitive and efficient and can be applied in chemical processes' enhancement, retrofitting, and fault diagnosis. A benzene alkylation process is studied, with the total annual cost decreased by 3.4 %.

Increasing access to cataract surgery in Counties Manukau by optimising the clinical pathway: a quality improvement report.

To streamline the cataract surgery pathway to improve the time from first specialist assessment (FSA) to surgery, while reducing the clinical priority assessment criteria (CPAC) score from 55 to 50. A quality improvement project using Lean Six Sigma tools and the Model for Improvement. Most data were collected from the i.Patient Manager (iPM) system and analysed using statistical process control charts. Change interventions included combining FSA and pre-admission clinics (PAC); post-operative telephone review by non senior medical officers (SMO); and using our own surgeons in private theatres. The standard cataract pathway was reduced from 5 to 3 appointments. This removed 1,514 hours of appointments, released 113 SMO hours and saved patients NZ$156,000 in indirect costs over a year. The average waiting time from FSA to surgery decreased from 90 to 77 days (-13.5%). The number of overdue patients reduced from 127 to 44 (-35%). The average number of patients on the FSA waiting list dropped from 322 to 205 (-40%). There was no change to the proportions of surgeries or appointment attendance rates by ethnicity. Average monthly cataract surgeries increased from 192 to 215 (+12%), and the CPAC score threshold was decreased to 50 in February 2021. Despite significant demand pressures, and the disruptions of COVID-19, we were able to reduce the CPAC score for accessing cataract surgery by optimising the clinical pathway to better utilise staff capacity and maximise value for patients.

Study on Ecological Water Demand Pressure of Forest and Grass Vegetation Construction in Northwest Loess Plateau Based on Fitting Verification

In this paper, the minimum ecological water requirement of forest and grass vegetation in different types and regions and small basins in Pingliang City was analyzed and evaluated by using the quota of water consumption for ecological construction. The actual evapotranspiration water consumption of different types of vegetation was used as the quota to calculate the appropriate ecological water demand of vegetation, and the actual evapotranspiration water consumption of vegetation was used as the quota to calculate the appropriate ecological water consumption of vegetation in this region. At the same time, in order to make the calculation result more accurate, the water consumption per unit area after the actual evapotranspiration of different regions and different types of vegetation is used as the calculation quota. In addition, according to the principles of similar vegetation types, similar site conditions and similar climate environment, the research results of He Wentao et al., Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, on the ecological water requirement of forest in the whole Jinghe River basin (He Wentao et al. Determination and calculation of ecological water requirement of forest vegetation, Journal of Soil and Water Conservation, 2004, 18(6)) were selected and compared with this study. This study verifies the reliability of the calculation results of evapotranspiration water consumption of vegetation in this area. It should be noted that He Wentao et al. also evaluated the ecological water requirement of vegetation in the whole Jinghe River basin by calculating the evapotranspiration water consumption of vegetation, and analyzed the vegetation ecological water requirement deficit in 2020 by comparing the calculated minimum ecological water requirement of vegetation in the region, so as to reflect the ecological water demand pressure faced by vegetation construction in the region. It provides a basic basis for coordinating the relationship between vegetation construction and water resources in this region.

A Qualitative Inquiry Into the Occupational Challenges Faced by Home-Based Caregivers of People Living With HIV in South Africa’s Gauteng Province

Community home-based caregivers caring for people living with human immunodeficiency virus (PLWHIV) are instrumental in relieving the demand pressures experienced by healthcare service centers. Although their contributions to the healthcare system are essential, they do so under difficult conditions necessitating social work support. This study was conducted in the Gauteng province of South Africa in 2017 to explore the occupational challenges faced by community home-based care caregivers of PLWHIV. Following the qualitative research approach, eighteen caregivers were identified and sampled using purposive and snowball sampling techniques in semi-structured interviews. The data was manually analyzed according to Tesch’s eight steps of qualitative data analysis. This gave rise to four themes: reception by community members, uncooperative clients and families, unsupportive healthcare professionals, and working in unsafe conditions. Following relevant ethical principles such as informed consent, confidentiality, and anonymity throughout the study, trustworthiness was continuously upheld through the principles of prolonged engagement, triangulation, member checking, thick description, and audit trail. The need for psychosocial support programs for caregivers, community and family educational programs, and strengthening partnerships for caregivers, communities, and healthcare professionals is recommended, given the success of community home-based care (CHBC) services for PLWHIV.

High stress, high demand and high pressure: Experiences of social work and human services agencies during Melbourne's COVID‐19 lockdowns

AbstractThe COVID‐19 pandemic has created major challenges globally. The social work and human services profession has been required to rapidly respond to policy and social changes. This research aimed to understand how the pandemic has affected social work and human services staff within Melbourne, Victoria. In this paper, we analyse the practice and policy implications of these responses, and outline learning for the human services sector. We draw on interviews with social work and human services practitioners, exploring their experiences during the pandemic, including social and economic impacts on service users and agencies, and organisational and practice changes. Participants highlight compliance requirements, digitalisation of services, loss of social connection for service users and service impacts. In addition, participants highlight how people from low socioeconomic backgrounds were immensely affected throughout COVID‐19 lockdowns. However, this research also identifies service benefits, resulting from the rapid adjustments made by agencies that need further exploration for future practice. This article highlights how, despite the challenges posed by COVID‐19, agencies and workers developed innovative responses to this crisis. Drawing on these insights can help to understand how such initiatives can be implemented in the future. This article contributes to knowledge about innovation in a time of crisis.

The hidden toll of the pandemic: Excess mortality in non-COVID-19 hospital patients

Seasonal infectious diseases can cause demand and supply pressures that reduce the ability of healthcare systems to provide high-quality care. This may generate negative spillover effects on the health outcomes of patients seeking medical help for unrelated reasons. Separating these indirect burdens from the direct consequences for infected patients is usually impossible due to a lack of suitable data and an absence of population testing. However, this paper finds robust empirical evidence of excess mortality among non-COVID-19 patients in an integrated public healthcare system: the English National Health Service (NHS). Analysing the forecast error in the NHS’ model for predicted mortality, we find at least one additional excess death among patients who sought medical help for reasons unrelated to COVID-19 for every 42 COVID-19-related deaths in the population. We identify COVID-19 pressures as a key driver of non-COVID-19 excess mortality in NHS hospitals during the pandemic, and characterize the hospital populations and medical conditions that were disproportionately affected. Our findings have substantive relevance in shaping our understanding of the wider burden of COVID-19, and other seasonal diseases more generally, and can contribute to debates on optimal public health policy.

An uncoupled approach for estimating seismic-induced pore water pressures in liquefiable sandy soils

Proper evaluation of seismic-induced excess pore water pressures in saturated sandy soils is still an open issue, which can be tackled with fully coupled to uncoupled approaches. The former are more accurate but computationally onerous, while the latter require seismic demand and pore pressure build-up to be computed in two successive steps, typically employing simple constitutive assumptions.Starting from the work by Seed et al. (1975), this paper presents a novel uncoupled procedure to compute excess water pressures developing in a 1D soil column under partially drained conditions, when subjected to horizontal seismic excitations. Fundamental modifications are introduced to account for: non-uniform distribution of equivalent loading cycles; soil stiffness degradation; and modification of the frequency content of ground motion due to pore pressure build-up.The approach was implemented in Matlab via the Finite Difference Method and validated against both fully-coupled Finite Element analyses and one centrifuge test. An extensive parametric study was also performed for a two-layer soil column, by varying the thickness and hydraulic conductivity of the shallow layer, as well as the seismic input. The good agreement with both numerical and experimental data demonstrates that key features of liquefaction are well-captured by the proposed uncoupled approach.

Aboveground hydrogen storage – Assessment of the potential market relevance in a Carbon-Neutral European energy system

Hydrogen storage is expected to play a crucial role in the comprehensive defossilization of energy systems. In this context, the focus is typically on underground hydrogen storage (e.g., in salt caverns). However, aboveground storage, which is independent of geological conditions and might offer other technical advantages, could provide systemic benefits and, thereby, gain shares in the hydrogen storage market. Against this background, this paper examines the market relevance of aboveground compared to underground hydrogen storage. Using the open-source energy system model and optimization framework of Europe, PyPSA-Eur, the influence of geological independence, storage cost relations, and technical storage characteristics (i.e., efficiencies) on mentioned market relevance of aboveground hydrogen storage are investigated. Further, the expectable market relevance based on current cost projections for the future is assessed. The studies show that in terms of hydrogen capacities, aboveground hydrogen storage plays a considerably smaller role compared to underground hydrogen storage. Even when assuming comparatively low aboveground storage cost, it will not exceed 1.7% (1.9TWhH2,LHV) of total hydrogen storage capacities in a cost-optimal European energy system. Regarding the amounts of annually stored hydrogen, aboveground storage could play a larger role, reaching a maximum share of 32.5% (168TWhH2,LHVa-1) of total stored hydrogen throughout Europe. However, these shares are only achievable for low cost storage in particularly suited energy system supply configurations. For higher aboveground storage costs or lower efficiencies, shares drop below 10% sharply. The analysis identifies some especially influential factors for achieving higher market relevance. Besides storage costs, the demand-orientation of a particular aboveground storage system (e.g., hydrogen storage at demand pressure levels) plays an essential role in market relevance. Further, overall efficiency can be a beneficial factor. Still, current projections of future techno-economic characteristics show that aboveground hydrogen storage is too expensive or too inefficient compared to underground storage. Therefore, to achieve notable market relevance, rather drastic cost reductions beyond current expectations would be needed for all assessed aboveground hydrogen storage technologies.

The Overlooked Potential of Sulfated Zirconia: Reexamining Solid Superacidity Toward the Controlled Depolymerization of Polyolefins.

Closed-loop recycling via an efficient chemical process can help alleviate the global plastic waste crisis. However, conventional depolymerization methods for polyolefins, which compose more than 50% of plastics, demand high temperatures and pressures, employ precious noble metals, and/or yield complex mixtures of products limited to single-use fuels or oils. Superacidic forms of sulfated zirconia (SZrO) with Hammet Acidity Functions (H0) ≤ - 12 (i.e., stronger than 100% H2SO4) are industrially deployed heterogeneous catalysts capable of activating hydrocarbons under mild conditions and are shown to decompose polyolefins at temperatures near 200 °C and ambient pressure. Additionally, confinement of active sites in porous supports is known to radically increase selectivity, coking and sintering resistance, and acid site activity, presenting a possible approach to low-energy polyolefin depolymerization. However, a critical examination of the literature on SZrO led us to a surprising conclusion: despite 40 years of catalytic study, engineering, and industrial use, the surface chemistry of SZrO is poorly understood. Ostensibly spurred by SZrO's impressive catalytic activity, the application-driven study of SZrO has resulted in deleterious ambiguity in requisite synthetic conditions for superacidity and insufficient characterization of acidity, porosity, and active site structure. This ambiguity has produced significant knowledge gaps surrounding the synthesis, structure, and mechanisms of hydrocarbon activation for optimized SZrO, stunting the potential of this catalyst in olefin cracking and other industrially relevant reactions, such as isomerization, esterification, and alkylation. Toward mitigating these long extant issues, we herein identify and highlight these current shortcomings and knowledge gaps, propose explicit guidelines for characterization of and reporting on characterization of solid acidity, and discuss the potential of pore-confined superacids in the efficient and selective depolymerization of polyolefins.

The role of intermediaries in derivatives markets: Evidence from VIX options

Consistent with models of intermediaries who absorb demand pressure from end-users and respond by changing prices, net option demand is positively related to option prices in the market for VIX puts and calls. VIX and SPX option markets are integrated: market-makers absorb end-users’ net long volatility positions and net demand affects prices across markets. Net demand changes in the most liquid markets result in spillover effects between the VIX and SPX markets. A dynamic characterization of prices and net demand suggests that VIX option markets and the SPX put market are integrated, while the SPX call market is more segregated.

The green corporate bond issuance premium

We study a global panel of green and conventional corporate bonds to assess the borrowing cost advantage at issuance for green bond issuers. We find that, on average, green corporate bonds have a yield spread that is between 3 and 8 basis points lower relative to conventional bonds, depending on the regression specification. We link this borrowing cost advantage, or “greenium,” to demand pressure at issuance, highlighting a key mechanism through which the greenium is allocated. We find that a significant greenium emerges only as of 2019, coinciding with the growth of the sustainable asset management industry following EU regulation. While green bond governance and external review appear to matter for the greenium, the credibility of the underlying projects has little impact. Instead, the greenium is unevenly distributed to large, investment-grade issuers, primarily within the banking sector and developed economies. These findings have implications for the role of green bonds in incentivizing meaningful green investments throughout the global economy.

Environmental Risks and Agricultural Commodities

As natural disasters are expected to increase both in severity and frequency, their impact on agricultural commodities and the food supply chain is likely to rise in tandem. We use a unique data set of natural disasters that occurred globally between 1970 and 2015 and study their impact on the price and price volatility of eight globally traded agricultural commodities that account for more than 75% of the food supply in the world. Our results show that price and the price volatility of commodities are impacted around the occurrence of a natural disaster in producing countries. In addition, we find that the affected country’s production shares, the total damage caused by a natural disaster relative to the affected country’s GDP, and the demand pressure for the commodity have an impact on the magnitude of price and price volatility changes of a given commodity around the occurrence of a natural disaster.

Modeling cerebrovascular responses to assess the impact of the collateral circulation following middle cerebral artery occlusion.

An improved understanding of the role of the leptomeningeal collateral circulation in blood flow compensation following middle cerebral artery (MCA) occlusion can contribute to more effective treatment development for ischemic stroke. The present study introduces a model of the cerebral circulation to predict cerebral blood flow and tissue oxygenation following MCA occlusion. The model incorporates flow regulation mechanisms based on changes in pressure, shear stress, and metabolic demand. Oxygen saturation in cerebral vessels and tissue is calculated using a Krogh cylinder model. The model is used to assess the effects of changes in oxygen demand and arterial pressure on cerebral blood flow and oxygenation after MCA occlusion. An increase from five to 11 leptomeningeal collateral vessels was shown to increase the oxygen saturation in the region distal to the occlusion by nearly 100%. Post-occlusion, the model also predicted a loss of autoregulation and a decrease in flow to the ischemic territory as oxygen demand was increased; these results were consistent with data from experiments that induced cerebral ischemia. This study highlights the importance of leptomeningeal collaterals following MCA occlusion and reinforces the idea that lower oxygen demand and higher arterial pressure improve conditions of flow and oxygenation.