Summary Recognition of the need for evidence-based interventions to help to improve the effectiveness and efficiency of humanitarian responses has been increasing. However, little is known about the ...breadth and quality of evidence on health interventions in humanitarian crises. We describe the findings of a systematic review with the aim of examining the quantity and quality of evidence on public health interventions in humanitarian crises to identify key research gaps. We identified 345 studies published between 1980 and 2014 that met our inclusion criteria. The quantity of evidence varied substantially by health topic, from communicable diseases (n=131), nutrition (n=77), to non-communicable diseases (n=8), and water, sanitation, and hygiene (n=6). We observed common study design and weaknesses in the methods, which substantially reduced the ability to determine causation and attribution of the interventions. Considering the major increase in health-related humanitarian activities in the past three decades and calls for a stronger evidence base, this paper highlights the limited quantity and quality of health intervention research in humanitarian contexts and supports calls to scale up this research.
Risk perception has been found to be a crucial factor explaining inconsistent or non-use of HIV prevention interventions. Considerations of risk need to expand beyond risk of infection to also ...include the personal, social, emotional, and economic risks associated with prevention intervention use.
This systematic review of qualitative peer-reviewed literature from sub-Saharan Africa examines perceptions of risk associated with HIV infection and HIV prevention intervention use.
We searched Medline, Embase, PsychInfo, Africa Wide Info, CINAHL, and Global Health for publications and screened them for relevance.
Peer-reviewed qualitative studies published since 2003 were eligible for inclusion if they examined risk perception or uncertainty in the context of a medically regulated intervention. Only studies focusing on adults were included.
Included publications were quality assessed using the Hawker method and coded thematically.
10318 unique papers were identified, of which 29 are included. Among the themes identified, a particularly salient one was the potential of HIV prevention interventions to threaten the stability of a relationship and impact on how and when people may-or may not-choose to use prevention interventions.
This literature review excludes grey-literature, which may have distinct valuable insights. We also excluded quantitative studies that may have challenged or triangulated our findings.
When considering the risk of HIV acquisition, it is insufficient to examine biological risk in isolation from the personal, relational and economic costs associated with intervention use. This loss of emotional, physical, or material support may be perceived as more consequential than the prevention of a potential infection.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Solar Water Splitting Cells Walter, Michael G; Warren, Emily L; McKone, James R ...
Chemical reviews,
11/2010, Letnik:
110, Številka:
11
Journal Article
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Solar water splitting cells that were developed to split water on the surface of semiconductors are discussed. A photoelectrolysis cell design is also described.
•UA may improve dietary diversity in developing and transitional economies.•Evidence suggests that UA may be associated with improved food security.•Poor quality and weak study designs hinder ...interpretation and assessing causation.
This literature review seeks to examine the evidence for the association between urban agriculture (UA) and food security, dietary diversity, and nutritional status and clarify the evidence base for its effectiveness at ameliorating some food security challenges faced by urban residents.
We searched five databases, five grey literature libraries, and hand-searched reference lists to identify all potentially relevant sources. To be included a paper needed to quantify the impact of UA on food security, dietary diversity, or nutrition status. Papers were screened and quality assessed and data were extracted in duplicate.
Developing and transitional economies.
Urban farmers, their households, and communities.
We identified 11,192 potentially relevant studies and included 13 papers from 12 unique studies. Studies identified both positive and no associations with UA and food security, and in one study’s sub-analysis, negative associations were detected. Weak study designs and methods, incomparable measures, compounded with the finding that food insecure households are more likely to engage in UA, all make interpretations difficult. All studies that measured dietary diversity found a positive association. Most studies found a positive association between engagement in UA and food consumption. Findings for nutritional status were mixed, some showing positive associations for stunting.
Poor quality and weak study designs made interpretation difficult and the assignment of causation impossible. The evidence base for UA needs to be strengthened before it can be confidently recommended as a strategy to improve urban food security. We did not however, find any evidence to discourage its use.
The dark electrocatalytic and light photocathodic hydrogen evolution properties of Ni, Ni-Mo alloys, and Pt on Si electrodes have been measured, to assess the viability of earth-abundant ...electrocatalysts for integrated, semiconductor coupled fuel formation. In the dark, the activities of these catalysts deposited on degenerately doped p+-Si electrodes increased in the order Ni Ni-Mo less-than-or-equal Pt. Ni-Mo deposited on degenerately doped Si microwires exhibited activity that was very similar to that of Pt deposited by metal evaporation on planar Si electrodes. Under 100 mW cm-2 of Air Mass 1.5 solar simulation, the energy conversion efficiencies of p-type Si/catalyst photoelectrodes ranged from 0.2-1%, and increased in the order Ni approximate Ni-Mo Pt, due to somewhat lower photovoltages and photocurrents for p-Si/Ni-Mo relative to p-Si/Ni and p-Si/Pt photoelectrodes. Deposition of the catalysts onto microwire arrays resulted in higher apparent catalytic activities and similar photoelectrode efficiencies than were observed on planar p-Si photocathodes, despite lower light absorption by p-Si in the microwire structures.
The development of highly stable and efficient wide-bandgap (WBG) perovskite solar cells (PSCs) based on bromine-iodine (Br-I) mixed-halide perovskite (with Br greater than 20%) is critical to create ...tandem solar cells. However, issues with Br-I phase segregation under solar cell operational conditions (such as light and heat) limit the device voltage and operational stability. This challenge is often exacerbated by the ready defect formation associated with the rapid crystallization of Br-rich perovskite chemistry with antisolvent processes. We combined the rapid Br crystallization with a gentle gas-quench method to prepare highly textured columnar 1.75-electron volt Br-I mixed WBG perovskite films with reduced defect density. With this approach, we obtained 1.75-electron volt WBG PSCs with greater than 20% power conversion efficiency, approximately 1.33-volt open-circuit voltage (
), and excellent operational stability (less than 5% degradation over 1100 hours of operation under 1.2 sun at 65°C). When further integrated with 1.25-electron volt narrow-bandgap PSC, we obtained a 27.1% efficient, all-perovskite, two-terminal tandem device with a high
of 2.2 volts.
Si wire arrays are a promising architecture for solar-energy-harvesting applications, and may offer a mechanically flexible alternative to Si wafers for photovoltaics. To achieve competitive ...conversion efficiencies, the wires must absorb sunlight over a broad range of wavelengths and incidence angles, despite occupying only a modest fraction of the array's volume. Here, we show that arrays having less than 5% areal fraction of wires can achieve up to 96% peak absorption, and that they can absorb up to 85% of day-integrated, above-bandgap direct sunlight. In fact, these arrays show enhanced near-infrared absorption, which allows their overall sunlight absorption to exceed the ray-optics light-trapping absorption limit for an equivalent volume of randomly textured planar Si, over a broad range of incidence angles. We furthermore demonstrate that the light absorbed by Si wire arrays can be collected with a peak external quantum efficiency of 0.89, and that they show broadband, near-unity internal quantum efficiency for carrier collection through a radial semiconductor/liquid junction at the surface of each wire. The observed absorption enhancement and collection efficiency enable a cell geometry that not only uses 1/100th the material of traditional wafer-based devices, but also may offer increased photovoltaic efficiency owing to an effective optical concentration of up to 20 times.
While it is well documented that families involved in Child Protective Services (CPS) are likely to experience housing insecurity, the mechanisms that may account for the association between housing ...insecurity and child maltreatment remain unclear. We use data from the Fragile Families and Child Well-Being Study (FFCW) to examine associations between housing insecurity and child maltreatment risk. We assess three explanations for associations between housing insecurity and child abuse and neglect risk: a spurious association that is fully explained by economic factors, a direct association, and an indirect association that is mediated by maternal stress. Our results suggest that housing insecurity is directly associated with neglect risk and influences abuse and neglect risk through maternal stress. Our findings highlight the need for a more equitable housing assistance program that serves more low-income families that are at risk of maltreatment, as well as increased attention to housing insecurity by child welfare agencies as a point of intervention.
Terawatt-scale photovoltaics: Transform global energy Haegel, Nancy M; Atwater, Jr, Harry; Barnes, Teresa ...
Science (American Association for the Advancement of Science),
05/2019, Letnik:
364, Številka:
6443
Journal Article
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Improving costs and scale reflect looming opportunities
Solar energy has the potential to play a central role in the future global energy system because of the scale of the solar resource, its ...predictability, and its ubiquitous nature. Global installed solar photovoltaic (PV) capacity exceeded 500 GW at the end of 2018, and an estimated additional 500 GW of PV capacity is projected to be installed by 2022–2023, bringing us into the era of TW-scale PV. Given the speed of change in the PV industry, both in terms of continued dramatic cost decreases and manufacturing-scale increases, the growth toward TW-scale PV has caught many observers, including many of us (
1
), by surprise. Two years ago, we focused on the challenges of achieving 3 to 10 TW of PV by 2030. Here, we envision a future with ∼10 TW of PV by 2030 and 30 to 70 TW by 2050, providing a majority of global energy. PV would be not just a key contributor to electricity generation but also a central contributor to all segments of the global energy system. We discuss ramifications and challenges for complementary technologies (e.g., energy storage, power to gas/liquid fuels/chemicals, grid integration, and multiple sector electrification) and summarize what is needed in research in PV performance, reliability, manufacturing, and recycling.
Silicon wire arrays, though attractive materials for use in photovoltaics and as photocathodes for hydrogen generation, have to date exhibited poor performance. Using a copper-catalyzed, ...vapor-liquid-solid-growth process, SiCl₄ and BCl₃ were used to grow ordered arrays of crystalline p-type silicon (p-Si) microwires on p⁺-Si(111) substrates. When these wire arrays were used as photocathodes in contact with an aqueous methyl viologen²⁺/⁺ electrolyte, energy-conversion efficiencies of up to 3% were observed for monochromatic 808-nanometer light at fluxes comparable to solar illumination, despite an external quantum yield at short circuit of only 0.2. Internal quantum yields were at least 0.7, demonstrating that the measured photocurrents were limited by light absorption in the wire arrays, which filled only 4% of the incident optical plane in our test devices. The inherent performance of these wires thus conceptually allows the development of efficient photovoltaic and photoelectrochemical energy-conversion devices based on a radial junction platform.
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