The Evergreen Forests of Liberia: A Report on Investigations made in the West African Republic of Liberia by the Yale University School of Forestry in Cooperation with the Firestone Plantations Company

Liberia is a forested country and a large proportion of it is covered with what is popularly known as jungle. This is the region of abundant rainfall and the forests are evergreen. The term \u27evergreen\u27 refers to the fact that the forest appears in full leaf the year round and does not signify conifers, for in all the country there is not a Pine or Fir or Hemlock or Cedar, such as constitute the evergreen forests of the North. The West African forests are composed of broadleaf trees and palms

Potential of Demand Side Management to Reduce Carbon Dioxide Emissions Associated with the Operation of Heat Pumps

This work considers the potential reduction in the carbon dioxide emissions associated with the operation of Air Source Heat Pump which could be achieved by using demand side management. In order to achieve significant reductions in carbon dioxide emissions, it is widely envisioned that electrification of the heating sector will need to be combined with decarbonisation of the electrical supply. By influencing the times at when electric heat pumps operate such that they coincide more with electricity generation which has a low marginal carbon emissions factor, it has been suggested that these emissions could be reduced further. In order to investigate this possibility, models of the UK electrical grid based on scenarios for 2020 to 2050 have been combined with a dynamic model of an air source heat pump unit and thermal models of a population of dwellings. The performance and carbon dioxide emissions associated with the heat pumps are compared both with and without demand side management interventions intended to give preference to operation when the marginal emissions factor of the electricity being generated is low. It is found that these interventions are unlikely to be effective at achieving further reductions in emissions. A reduction of around 3% was observed in scenarios based around 2035 but in other scenarios the reduction was insignificant. In the scenarios with high wind generation (2050), the DSM scheme considered here tends to improve thermal comfort (with minimal increases in emissions) rather than achieving a decrease in emissions. The reasons for this are discussed and further recommendations are made

Enhanced normalisation of CD4/CD8 ratio with earlier antiretroviral therapy at Primary HIV Infection.

BACKGROUND: Total CD4 T-cell counts predict HIV disease progression, but do not necessarily reflect normalization of immune function. CD4/CD8 ratio is a marker of immune dysfunction, a prognostic indicator for non-AIDS mortality, and reflects viral reservoir size. Despite ART, recovery of CD4/CD8 ratio in chronic HIV infection is incomplete; we hypothesize enhanced CD4/CD8 ratio recovery with earlier treatment initiation in recently infected individuals. METHODS: CD4 count and CD4/CD8 ratio were analyzed using data from two cohorts: SPARTAC trial, and the UK HIV Seroconverters Cohort where Primary HIV infection (PHI) was defined as within 6 months from estimated date of infection. Using time-to-event methods and Cox proportional hazard models we examined the effect of CD4/CD8 ratio at seroconversion on disease progression (CD41.0). FINDINGS: Of 573 seroconverters, 482 (84%) had abnormal CD4/CD8 ratios at HIV seroconversion. Individuals with higher CD4/CD8 ratio at seroconversion were significantly less likely to reach the disease progression end point (aHR [95% CI] = 0.52 [0.32, 0.82], p=0.005). The longer the interval between seroconversion and ART initiation (HR [95% CI] =0.98 per month increase [0.97, 0.99], p<0.001) the less likely CD4/CD8 ratio normalization. ART initiation within 6 months from seroconversion was significantly more likely to normalize (HR [95% CI] =2.47 [1.67, 3.67], p<0.001) than those initiating later. INTERPRETATION: The majority of individuals presenting in PHI have abnormal CD4/CD8 ratios. The sooner ART is initiated in PHI the greater the probability of achieving normal CD4/CD8 ratio

Impact on energy requirements and emissions of heat pumps and micro-cogenerators participating in demand side management

Belgium Herbarium image of Meise Botanic Garden

Detailed simulation of electrical demands due to nationwide adoption of heat pumps, taking account of renewable generation and mitigation

This study quantifies the increase in the peak power demand, net of non-dispatchable generation, that may be required by widespread adoption of heat pumps. Electrification of heating could reduce emissions but also cause a challenging increase in peak power demand. This study expands on previous studies by quantifying the increase in greater detail; considering a wider range of scenarios, the characteristics of heat pumps and the interaction between wind generation and demand side management (DSM). A model was developed with dynamic simulations of individual heat pumps and dwellings. The increase in peak net-demand is highly sensitive to assumptions regarding the heat pumps, their installation, building fabric and the characteristics of the grid. If 80% of dwellings in the UK use heat pumps, peak net-demand could increase by around 100% (54 GW) but this increase could be mitigated to 30% (16 GW) by favourable conditions. DSM could reduce this increase to 20%, or 15% if used with extensive thermal storage. If 60% of dwellings use heat pumps, the increase in peak net-demand could be as low as 5.5 GW. High-performance heat pumps, appropriate installation and better insulated dwellings could make the increase in peak net-demand due to the electrification of heating more manageable

Potential of Demand Side Management to Reduce Carbon Dioxide Emissions Associated with the Operation of Heat Pumps

This work considers the potential reduction in the carbon dioxide emissions associated with the operation of Air Source Heat Pump which could be achieved by using demand side management. In order to achieve significant reductions in carbon dioxide emissions, it is widely envisioned that electrification of the heating sector will need to be combined with decarbonisation of the electrical supply. By influencing the times at when electric heat pumps operate such that they coincide more with electricity generation which has a low marginal carbon emissions factor, it has been suggested that these emissions could be reduced further. In order to investigate this possibility, models of the UK electrical grid based on scenarios for 2020 to 2050 have been combined with a dynamic model of an air source heat pump unit and thermal models of a population of dwellings. The performance and carbon dioxide emissions associated with the heat pumps are compared both with and without demand side management interventions intended to give preference to operation when the marginal emissions factor of the electricity being generated is low. It is found that these interventions are unlikely to be effective at achieving further reductions in emissions. A reduction of around 3% was observed in scenarios based around 2035 but in other scenarios the reduction was insignificant. In the scenarios with high wind generation (2050), the DSM scheme considered here tends to improve thermal comfort (with minimal increases in emissions) rather than achieving a decrease in emissions. The reasons for this are discussed and further recommendations are made

Single electron-spin memory with a semiconductor quantum dot

We show storage of the circular polarisation of an optical field, transferring it to the spin-state of an individual electron confined in a single semiconductor quantum dot. The state is subsequently readout through the electronically-triggered emission of a single photon. The emitted photon shares the same polarisation as the initial pulse but has a different energy, making the transfer of quantum information between different physical systems possible. With an applied magnetic field of 2 Tesla, spin memory is preserved for at least 1000 times more than the exciton's radiative lifetime.Comment: 7 pages, 4 figure