Prospects of a virtual power plant to control a cluster of Distributed Generation and Renewable Energy Sources

The integration of distributed generation (DG) and renewable energy sources (RES) in the passive controlled distribution networks leads in present situation to an expansion of the network capacity and thus to excessive investments. If no measures will be taken these expenditures will increase in proportion to the growth of DG&RES. The virtual power plant (VPP) anticipates these challenges and in addition facilitates better dispatching of power and energy from centralized generation to the DG&RES. The VPP offers a concept for the control and management system of DG&RES that responds to the regulatory and socio-economical constraints beside technical challenges. While most VPP concepts are based on active distribution networks, this work uses the VPP concept to transit the present passive distribution networks to the active networks in the future. For that purpose three transition stages are developed after laying of the foundations for a definition of the VPP with the Dutch situation as an example. To anticipate future developments in the electricity infrastructures, the capability of the VPP to combine with the common known control and management concepts is investigate

Influence of Effective Microorganisms on Qualities of Tomatoes (Lycopersicon esculentum) Grown on Tropical Loam Soil

The use of Effective Microorganism (EM) consortium along with compost may overcome the harmful effects caused by chemical fertilizer while improving the nutritional quality of crops. The study aimed to determining the influence of compost inoculated with EM on the nutritional qualities of tomatoes (Lycopersicon esculentum) grown in tropical loam soil.  Four sets of treated loamy soils was experimented. The treatments were the compost without EM (C); compost containing effective microorganisms (EM); compost containing effective microorganisms with chicken manure (CEM) and urea as mineral fertilizer (M). Tomatoes were harvested randomly after matured and kept in plastic bag and immediately transferred to the laboratory for analysis of beta-carotene, vitamin C and brix contents.  The results shows that tomatoes planted with EM inoculated compost have relatively higher level of β-Carotene (7.76µg/100g), Brix (4.9%), and vitamin C (77.55mg/100g) compared with those from mineral 4.01µg/100g, 4.8%, and 3.83mg/100g respectively. This is likely reflect the efficiency of organic nature decomposition of EM compost over mineral fertilizers. We may therefore conclude that EM compost can be applied to supersede chemical fertilizer to promote sustainable and environmentally friendly tomatoes agriculture. Keywords: Beta-carotene, Brix, Compost, Effective microorganisms, Vitamin C

Basis for treatment of tuberculosis among HIV-infected patients in Tanzania: the role of chest x-ray and sputum culture

BACKGROUND: Active tuberculosis (TB) is common among HIV-infected persons living in tuberculosis endemic countries, and screening for tuberculosis (TB) is recommended routinely. We sought to determine the role of chest x-ray and sputum culture in the decision to treat for presumptive TB using active case finding in a large cohort of HIV-infected patients. METHODS: Ambulatory HIV-positive subjects with CD4 counts ≥ 200/mm3 entering a Phase III TB vaccine study in Tanzania were screened for TB with a physical examination, standard interview, CD4 count, chest x-ray (CXR), blood culture for TB, and three sputum samples for acid fast bacillus (AFB) smear and culture. RESULTS: Among 1176 subjects 136 (12%) were treated for presumptive TB. These patients were more frequently male than those without treatment (34% vs. 25%, respectively; p = 0.049) and had lower median CD4 counts (319/μL vs. 425/μL, respectively; p < .0001). Among the 136 patients treated for TB, 38 (28%) had microbiologic confirmation, including 13 (10%) who had a normal CXR and no symptoms. There were 58 (43%) treated patients in whom the only positive finding was an abnormal CXR. Blood cultures were negative in all patients. CONCLUSION: Many ambulatory HIV-infected patients with CD4 counts ≥ 200/mm3 are treated for presumptive TB. Our data suggest that optimal detection requires comprehensive evaluation, including CXR and sputum culture on both symptomatic and asymptomatic subjects.National Institutes of Health (A1 45407); Fogarty International Center (D43-TW006807

Intensive Case Finding and Isoniazid Preventative Therapy in HIV Infected Individuals in Africa: Economic Model and Value of Information Analysis

Background: Tuberculosis (TB) accounts of much of the morbidity and mortality associated with HIV. We evaluate the costeffectiveness of different strategies to actively screen for TB disease in HIV positive individuals, where isoniazid preventative therapy (IPT) is given to those screening negative, and use value of information analysis (VOI) to identify future research priorities. Methodology / Principal Findings: We built an individual sampling model to investigate the costs (2010 US Dollars) and consequences of screening for TB, and providing TB treatment or IPT in adults testing HIV positive in Sub-Saharan Africa. A systematic review and meta-analysis was conducted to assess performance of the nine different TB screening strategies evaluated. Probabilistic sensitivity analysis was conducted to incorporate decision uncertainty, and expected value of perfect information for the entire model and for groups of parameters was calculated. Screening all HIV infected individuals with sputum microscopy was the least costly strategy, with other strategies not cost-effective at WHO recommended thresholds. Screening those with TB symptoms with sputum microscopy and CXR would be cost-effective at a threshold ICER of $7,800 per quality-adjusted life year (QALY), but associated with significant uncertainty. VOI analysis suggests further information would be of value. Conclusions / Significance: Resource-constrained countries in sub-Saharan Africa wishing to scale up TB preventativ

Promotion of couples' voluntary counselling and testing for HIV through influential networks in two African capital cities

<p>Abstract</p> <p>Background</p> <p>Most new HIV infections in Africa are acquired from cohabiting heterosexual partners. Couples' Voluntary Counselling and Testing (CVCT) is an effective prevention strategy for this group. We present our experience with a community-based program for the promotion of CVCT in Kigali, Rwanda and Lusaka, Zambia.</p> <p>Methods</p> <p>Influence Network Agents (INAs) from the health, religious, non-governmental, and private sectors were trained to invite couples for CVCT. Predictors of successful promotion were identified using a multi-level hierarchical analysis.</p> <p>Results</p> <p>In 4 months, 9,900 invitations were distributed by 61 INAs, with 1,411 (14.3%) couples requesting CVCT. INAs in Rwanda distributed fewer invitations (2,680 vs. 7,220) and had higher response rates (26.9% vs. 9.6%), than INAs in Zambia. Context of the invitation event, including a discreet location such as the INA's home (OR 3.3–3.4), delivery of the invitation to both partners in the couple (OR 1.6–1.7) or to someone known to the INA (OR 1.7–1.8), and use of public endorsement (OR 1.7–1.8) were stronger predictors of success than INA or couple-level characteristics.</p> <p>Conclusion</p> <p>Predictors of successful CVCT promotion included strategies that can be easily implemented in Africa. As new resources become available for Africans with HIV, CVCT should be broadly implemented as a point of entry for prevention, care and support.</p

Polyantigenic Interferon-γ Responses Are Associated with Protection from TB among HIV-Infected Adults with Childhood BCG Immunization

Surrogate immunologic markers for natural and vaccine-mediated protection against tuberculosis (TB) have not been identified. HIV-infected adults with childhood BCG immunization entering the placebo arm of the DarDar TB vaccine trial in Dar es Salaam, Tanzania, were assessed for interferon gamma (IFN-γ) responses to three mycobacterial antigen preparations--secreted Mycobacterium tuberculosis antigens 85 (Ag85), early secretory antigenic target 6 (ESAT-6) and polyantigenic whole cell lysate (WCL). We investigated the association between the number of detectable IFN-γ responses at baseline and the subsequent risk of HIV-associated TB. During a median follow-up of 3.3 years, 92 (9.4%) of 979 placebo recipients developed TB. The incidence of TB was 14% in subjects with no detectable baseline IFN-γ responses vs. 8% in subjects with response to polyantigenic WCL (P = 0.028). Concomitant responses to secreted antigens were associated with further reduction in the incidence of HIV-associated TB. Overall the percentage of subjects with 0, 1, 2 and 3 baseline IFN-γ responses to mycobacterial preparations who developed HIV-associated TB was 14%, 8%, 7% and 4%, respectively (P = 0.004). In a multivariate Cox regression model, the hazard of developing HIV-associated TB was 46% lower with each increment in the number of detectable baseline IFN-γ responses (P<0.001). Among HIV-infected adults who received BCG in childhood and live in a TB-endemic country, polyantigenic IFN-γ responses are associated with decreased risk of subsequent HIV-associated TB. ClinicalTrials.gov NCT0052195

Facilitating sustainability through smart network design in combination with virtual power plant operation

While smart grids are considered as an outcome to integrate a high penetration level of dispersed generation (DG) in the power system, most distribution networks are still passive controlled. To accelerate the transition towards smart grids network operators can take two important steps: 1. developing active distribution network through smart network design; and 2. facilitating active control of dispersed generation through virtual power plant (VPP) system. The role of the network operators with respect to the development of VPPs in the Netherlands is in the first place facilitating rather than operating the VPP system since they are prohibited by law from managing DG&amp;RES. On the other hand, their position in the unbundled electricity chain makes the network operators eligible to initiate the VPP systems in their own region. In addition, the development of an ICT infrastructure is necessary for the transition from passive to active controlled distribution network. Combining the ICT control systems of both VPP and distribution network will prevent excessive costs and benefit the involved operators and prosumers. In the distribution network of Liander, a network operator in the Netherlands, an active controlled backbone infrastructure is emerging as a first step towards smart grids. During the transition period the development of active networks and VPP systems is dependent on the increasing number of prosumers

Fitting distributed generation in future power markets through virtual power plants

This paper describes the development of a scalable virtual power plant system that fits in the deregulated power markets while benefiting from the Systems Engineering methodology. As this system facilitates energy trade, balancing and network support, it complies with the requirements of future active distribution grids and interests of the emerging active power users and producers. The technical conditions to embed large concentrations of distributed energy resources and other functions of this system are discussed while focusing on the benefits for the system stakeholders. This paper ends up with the business case of the virtual power plant and an overview of relevant conclusions