Primary production and humanosphere--is energy sufficient for sustainable humanosphere?
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There is a growing concern about the sustainability of our humanosphere. Realizing that our consumption of natural resources is soon to exhaust available ones in this globe, we feel the need for more prudent ways to utilize them. In particular, the need would be greater in the ways for the use of the primary products as we are to continue to face the rapid increase in human population. On the contrary, however, we are rapidly losing the traditional customs of their many uses. For instance, rice straws were once a significant raw material for many manufactured products in Japan, while most of them are now simply burned in the paddy. Here I would like to review the current status of primary production on the Earth from the viewpoint of material cycling and to demonstrate that, unless we quickly turn around our ever-increasing demand for more material and more energy, the humanosphere would never enter a stable phase. At the year 2006 A.D., the energy demand of a possibly sustainable humanosphere surpasses the available energy through the global primary production. (+info)
Solar flair.
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Design innovations and government-sponsored financial incentives are making solar energy increasingly attractive to homeowners and institutional customers such as school districts. In particular, the passive solar design concept of daylighting is gaining favor among educators due to evidence of improved performance by students working in daylit classrooms. Electricity-generating photovoltaic systems are also becoming more popular, especially in states such as California that have high electric rates and frequent power shortages. To help spread the word about solar power, the U.S. Department of Energy staged its first-ever Solar Decathlon in October 2002. This event featured solar-savvy homes designed by 14 college teams. (+info)
Use of thermodynamic orientors to assess the efficiency of ecosystems: a case study in the lagoon of Venice.
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So-called orientors have been introduced at the interface between ecology and thermodynamics. Two have been chosen here to compare the characteristics of five ecological systems: exergy, which is related to the degree of organization of a system and represents the biogeochemical energy of a system, and emergy, which is defined as the total amount of solar energy directly or indirectly required to generate a product or a service. They represent two complementary aspects of a system: the actual state and the past work needed to reach that state. The ratio of exergy to the emergy flow indicates the efficiency of an ecosystem in producing or maintaining its organization. The main system under study is a portion of the Venice Lagoon, which is used as a fish farming basin. Four other aquatic ecosystems were considered for comparison. Results show that the ecosystem within the Venice Lagoon is the one with the highest efficiency in transforming the available inputs in organization of the system. This fact is due to human intervention, which is very limited but also very effective. (+info)
Biophysical properties of the pelt of a diurnal marsupial, the numbat (Myrmecobius fasciatus), and its role in thermoregulation.
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Numbats are unusual marsupials in being exclusively diurnal and termitivorous. They have a sparse (1921 hairs cm(-2)) and shallow (1.19 mm) pelt compared with other marsupials. Coat reflectivity is low (19%) for numbats compared with nocturnal marsupials, but absorptivity is similar to that of diurnal North American ground squirrels (72%), indicating that the coat of the numbat may be adapted for acquisition of solar heat. Numbat coat thermal resistance decreases significantly with wind speed from 45.9 s m(-1) (at 0.5 m s(-1)) to 29.8 s m(-1) (at 3 m s(-1)). Erecting the fur significantly increases pelt depth (6.5 mm) and coat resistance (79.2-64.2 s m(-1)) at wind speeds between 0.5 m s(-1) and 3 m s(-1). Numbat coat resistance is much lower than that of other marsupials, and wind speed has a greater influence on coat resistance for numbats than for other mammals, reflecting the low pelt density and thickness. Solar heat gain by numbats through the pelt to the level of the skin (60-63%) is similar to the highest value measured for any mammal. However the numbat's high solar heat gain is not associated with the same degree of reduction in coat resistance as seen for other mammals, suggesting that its pelt has structural and spectral characteristics that enhance both solar heat acquisition and endogenous heat conservation. Maximum solar heat gain is estimated to be 0.5-3.6 times resting metabolic heat production for the numbat at ambient temperatures of 15-32.5 degrees C, so radiative heat gain is probably an important aspect of thermoregulation for wild numbats. (+info)
Photoelectrochemical solar cell using extract of Eugenia jambolana Lam as a natural sensitizer.
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The extract of Jambol o (java plum), Eugenia jambolana Lam, was used as a natural sensitizer of a wide band-gap semiconductor (TiO2) in photoelectrochemical solar cells. The natural dye, adsorbed onto the semiconductor surface, absorbs visible light and promotes electron transfer across the dye/semiconductor interface. Photogenerated current and voltage as high as 2.3 mA and 711 mV, respectively, were obtained and effective conversion of visible light into electricity was achieved. The use of a natural product as the semiconductor sensitizer enables a faster and simpler production of cheaper and environmentally friendly solar cells. (+info)
Applying a nutribusiness approach to increase animal source food consumption in local communities.
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Animal source foods (ASF) in the diets of schoolchildren are beneficial for supporting optimal physical and cognitive development. Nevertheless, behavioral change and economic development are needed to increase and sustain adequate meat product consumption by schoolchildren in developing countries. A NutriBusiness enterprise may be one way for local communities to promote economic development while increasing the availability of meat for children. This work evaluates the feasibility of a NutriBusiness enterprise involving the production of rabbits and the manufacture of solar dried snack food. Some rabbits would be kept for home use, whereas others would be used in the manufacture of a rabbit-sweet potato dried snack food that could be fed to children or sold for income. The NutriBusiness enterprise would be composed of participants from the community contributing to a cooperative effort for setting up a manufacturing facility and organizing production, manufacturing and marketing functions. A unit operation for rabbit-sweet potato Chiparoos, based on full-capacity operation of a single solar drier would involve up to 110 shareholder families, each producing 240 rabbits/y with 120 used at home and 120 sold for Chiparoos manufacture. Participation in the enterprise would increase the availability to children of iron, zinc and vitamin B-12, and other nutrients, and provide approximately 350 dollars/y additional income for the family. (+info)
Disinfection of contaminated water by using solar irradiation.
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Contaminated water causes an estimated 6 to 60 billion cases of gastrointestinal illness annually. The majority of these cases occur in rural areas of developing nations where the water supply remains polluted and adequate sanitation is unavailable. A portable, low-cost, and low-maintenance solar unit to disinfect unpotable water has been designed and tested. The solar disinfection unit was tested with both river water and partially processed water from two wastewater treatment plants. In less than 30 min in midday sunlight, the unit eradicated more than 4 log10 U (99.99%) of bacteria contained in highly contaminated water samples. The solar disinfection unit has been field tested by Centro Panamericano de Ingenieria Sanitaria y Ciencias del Ambiente in Lima, Peru. At moderate light intensity, the solar disinfection unit was capable of reducing the bacterial load in a controlled contaminated water sample by 4 log10 U and disinfected approximately 1 liter of water in 30 min. (+info)
Is rangeland agriculture sustainable?
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The objective of this paper is to examine the sustainability of rangeland agriculture (i.e., managed grazing) on a world-wide basis, with a focus on North America. Sustainability is addressed on three fronts: 1) ecological, 2) economic, and 3) social acceptance. Based on previous and on-going research, we suggest that employment of science-based rangeland grazing management strategies and tactics can ensure ecological sustainability. The formidable challenge in employing such technology centers around the need to balance efficiency of solar energy capture and subsequent harvest efficiencies across an array of highly spatially and temporally variable vegetation growing conditions using animals that graze selectively. Failure to meet this fundamental challenge often accelerates rangeland desertification processes, and in some instances, enhances rate and extent of the invasion of noxious weeds. We also suggest that the fundamental reason that ecologically sound grazing management technologies are often not employed in the management of grazed ecological systems is because social values drive management decisions more so than ecological science issues. This is true in both well-developed societies with substantial economic resources and in less-developed societies with few economic resources. However, the social issues driving management are often entirely different, ranging from multiple-use issues in developed countries to human day-to-day survival issues in poorly developed countries. We conclude that the long-term sustainability of rangeland agriculture in 1) developed societies depends on the ability of rangeland agriculturalists to continually respond in a dynamic, positive, proactive manner to ever-changing social values and 2) less-developed societies on their ability to address the ecological and social consequences arising from unsustainable human populations before the adoption of science-based sustainable rangeland management technologies. (+info)