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This paper analyses the causal relationship between Foreign Portfolio Investment (FPI), Equities Market Volatility, Exchange Rate and Inflation in Zimbabwe using a monthly time series data between October 2018 and November 2021. The granger causality model was used to present the link between the variables, and EGARCH was used to account for volatility and asymmetric effects on the variables. To incorporate innovations and responses into the Granger model, impulse response functions were used. Links between exchange rate and foreign portfolio investments were found. This only suggests that exchange rate volatility will vary when overseas investors purchase and sell financial securities on the Zimbabwe Stock Exchange (ZSE). In contrast, foreign investors sell local financial securities when local stock market returns are negative, leading to a significant outflow of foreign portfolio investment thereby reducing demand for currency. A significant causal relationship was found between the volatility of the exchange rate and stock market returns. It is assumed that stock market returns, and foreign portfolio investments are caused by fluctuating currency rates. The relationship between exchange rate and ZSE returns, and inflation was found based on Granger causality. This implies that stocks are not suitable for long-term investments that compensate investors for their diminished purchasing power. Policy makers should advise the Zimbabwe Stock Exchange to recommend a reduction in capital gains tax and withholding tax and this encourages investors to hold local equities for a long time.

Hydrogen is a zero-carbon energy carrier with potential to decarbonize industrial and transportation sectors, but its life-cycle greenhouse gas (GHG) emissions depend on its energy supply chain and carbon management measures (e.g., carbon capture and storage). Global support for clean hydrogen production and use has recently intensified. In the United States, Congress passed several laws that incentivize the production and use of renewable and low-carbon hydrogen, such as the Bipartisan Infrastructure Law (BIL) in 2021 and the Inflation Reduction Act (IRA) in 2022, which provides tax credits of up to $3/kg depending on the carbon intensity of the produced hydrogen. A comprehensive life-cycle accounting of GHG emissions associated with hydrogen production is needed to determine the carbon intensity of hydrogen throughout its value chain. In the United States, Argonne’s R&D GREET® (Greenhouse Gases, Regulated emissions, and Energy use in Technologies) model has been widely used for hydrogen carbon intensity calculations. This paper describes the major hydrogen technology pathways considered in the United States and provides data sources and carbon intensity results for each of the hydrogen production and delivery pathways using consistent system boundaries and most recent technology performance and supply chain data.

In air-cooled data centers, hot aisle containment is used to separate hot and cold air from mixing to improve cooling effectiveness. However, this creates a significant pressure imbalance between the cold and hot aisles, with the latter being high. The hot aisle high pressure creates bac pressure that pushes against the server-unit fan system, which subsequently results in hot recirculation and insufficient server-unit cooling. This study examines the application of series-configured server fans with the intention of increasing the system pressure head to overcome the hot aisle containment back pressure and eliminate server hot air recirculation. A detailed computational fluid dynamics model for the Dell 2950 2U server is calibrated and validated using existing experimental test results. Furthermore, the impact of changing the server fan system to a series configuration by adding four or more server fans is investigated under different hot-aisle pressure conditions. It was found that changing the server fan system configuration from parallel to series arrangement positively improved the available system static pressure, but it did not result in the elimination of hot air recirculation. The server with the series-configured fan system experienced an average inlet air temperature increase of 9% when compared to the original server under similar conditions. This study serves as a base for integrating liquid and air-cooling systems to form hybrid cooling systems for high-density racks in legacy data centers.

In air-cooled data centers, hot aisle containment is used to separate hot and cold air from mixing to improve cooling effectiveness. However, this creates a significant pressure imbalance between the cold and hot aisles, with the latter being high. The hot aisle high pressure creates bac pressure that pushes against the server-unit fan system, which subsequently results in hot recirculation and insufficient server-unit cooling. This study examines the application of series-configured server fans with the intention of increasing the system pressure head to overcome the hot aisle containment back pressure and eliminate server hot air recirculation. A detailed computational fluid dynamics model for the Dell 2950 2U server is calibrated and validated using existing experimental test results. Furthermore, the impact of changing the server fan system to a series configuration by adding four or more server fans is investigated under different hot-aisle pressure conditions. It was found that changing the server fan system configuration from parallel to series arrangement positively improved the available system static pressure, but it did not result in the elimination of hot air recirculation. The server with the series-configured fan system experienced an average inlet air temperature increase of 9% when compared to the original server under similar conditions. This study serves as a base for integrating liquid and air-cooling systems to form hybrid cooling systems for high-density racks in legacy data centers. [ABSTRACT FROM AUTHOR]

In Africa, antiretroviral therapy (ART) is delivered with limited laboratory monitoring, often none. In 2003-2004, investigators in the Development of Antiretroviral Therapy in Africa (DART) Trial randomized persons initiating ART in Uganda and Zimbabwe to either laboratory and clinical monitoring (LCM) or clinically driven monitoring (CDM). CD4 cell counts were measured every 12 weeks in both groups but were only returned to treating clinicians for management in the LCM group. Follow-up continued through 2008. In observational analyses, dynamic marginal structural models on pooled randomized groups were used to estimate survival under different monitoring-frequency and clinical/immunological switching strategies. Assumptions included no direct effect of randomized group on mortality or confounders and no unmeasured confounders which influenced treatment switch and mortality or treatment switch and time-dependent covariates. After 48 weeks of first-line ART, 2,946 individuals contributed 11,351 person-years of follow-up, 625 switches, and 179 deaths. The estimated survival probability after a further 240 weeks for post-48-week switch at the first CD4 cell count less than 100 cells/mm(3) or non-Candida World Health Organization stage 4 event (with CD4 count