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Topic Review
Río Negro Province
Río Negro (Spanish pronunciation: [ˈri.o ˈneɣɾo], Black River) is a province of Argentina , located at the northern edge of Patagonia. Neighboring provinces are from the south clockwise Chubut, Neuquén, Mendoza, La Pampa and Buenos Aires. To the east lies the Atlantic Ocean. Its capital is Viedma, and its largest city is Bariloche. Other important cities include General Roca and Cipolletti.
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  • 14 Oct 2022
Topic Review
Climate Fiction
Climate fiction (sometimes shortened cli-fi) is literature that deals with climate change and global warming. Not necessarily speculative in nature, works may take place in the world as we know it or in the near future. University courses on literature and environmental issues may include climate change fiction in their syllabi. This body of literature has been discussed by a variety of publications, including The New York Times , The Guardian , and Dissent magazine, among other international media outlets.
  • 1.5K
  • 14 Oct 2022
Topic Review
Weichselian Glaciation
Weichselian glaciation[upper-alpha 1] refers to the last glacial period and its associated glaciation in northern parts of Europe. In the Alpine region it corresponds to the Würm glaciation. It was characterized by a large ice sheet (the Fenno-Scandian ice sheet) that spread out from the Scandinavian Mountains and extended as far as the east coast of Schleswig-Holstein, the March of Brandenburg and Northwest Russia. In Northern Europe it was the youngest of the glacials of the Pleistocene ice age. The preceding warm period in this region was the Eemian interglacial. The last cold period began about 115,000 years ago and ended 11,700 years ago. Its end corresponds with the end of the Pleistocene epoch and the start of the Holocene. The German geologist Konrad Keilhack (de) (1858-1944) named Weichselian glaciation using the German-language name (Weichsel) of the River Vistula (Polish: Wisła) in present-day Poland.
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  • 14 Oct 2022
Topic Review
Classical Plant Breeding
Classical plant breeding uses deliberate interbreeding (crossing) of closely or distantly related species to produce new crops with desirable properties. Plants are crossed to introduce traits/genes from a particular variety into a new genetic background. For example, a mildew resistant pea may be crossed with a high-yielding but susceptible pea, the goal of the cross being to introduce mildew resistance without losing the high-yield characteristics. Progeny from the cross would then be crossed with the high-yielding parent to ensure that the progeny were most like the high-yielding parent, (backcrossing), the progeny from that cross would be tested for yield and mildew resistance and high-yielding resistant plants would be further developed. Plants may also be crossed with themselves to produce inbred varieties for breeding. Germplasm resources from genebanks have invaluable for classical breeding. Classical breeding relies heavily on the naturally occuring plant life-cycle and homologous recombination to generate genetic diversity and to eliminate undesirable traits. It may also makes use of a variety of artificial laboratory procedures to overcome obstacles to introduction of useful traits from wild species that do not usually exchange genes with the domesticated line. These approaches include in vitro techniques such as protoplast fusion, embryo rescue or mutagenisis (see below) to generate genetic alterations and produce transgenic plants that would not exist in nature. Traits that breeders' have tried to incorporate into crop plants in the last 100 years include: Intraspecific hybridization within a plant species was demonstrated by Charles Darwin and Gregor Mendel, and was further developed by geneticists and plant breeders. In the early 20th century, plant breeders realized that Mendel's findings on the non-random nature of inheritance could be applied to seedling populations produced through deliberate pollinations to predict the frequencies of different types. In 1908, George Harrison Shull described heterosis, also known as hybrid vigor. Heterosis describes the tendency of the progeny of a specific cross to outperform both parents. The detection of the usefulness of heterosis for plant breeding has lead to the development of inbred lines that reveal a heterotic yield advantage when they are crossed. Maize was the first species where heterosis was widely used to produce hybrids. Heterosis made breeders aware of the broad practical value of many genes carried in plant chromosomes even when the identity and trait specified by the paticular genes is unknown - that is that diverse plant Germplasm is generally valuable to the breeder. By the 1920s, statistical methods were developed to analyze gene action and distinguish heritable variation from variation caused by environment. In 1933, another important breeding technique, cytoplasmic male sterility (CMS), developed in maize, was described by Marcus Morton Rhoades. CMS is a maternally inherited trait that makes the plant produce sterile pollen, enabling the production of hybrids and removing the need for detasseling maize plants. The scientific use of Transgenic plants in farming gained impetus in the 1930s when a transgenic wheat variety named Hope bred by E. S. McFadden with a transgene originating in a wild grass saved American wheat growers from devastating stem rust outbreaks. These early breeding techniques resulted in large yield increase in the United States in the early 20th century. Similar yield increases were not produced elsewhere until after World War II, the Green Revolution increased crop production in the developing world in the 1960s. Success stories like Hope and hybrid-vigor made it clear that genetic divesity present in wild-species was of great potential value to plant breeders, and eventially lead to the establisment of Germplasm collections consisting of seed-banks devoted to preservation of potentially useful uncharacterised traits for posterity. Following World War II a number of techniques were developed that allowed plant breeders to hybridize distantly related species, and artificially induce genetic diversity. When distantly related species are crossed, plant breeders make use of a number of plant tissue culture techniques to produce progeny from other wise fruitless mating. Interspecific and intergeneric hybrids are produced from a cross of related species or genera that do not normally sexually reproduce with each other. These crosses are referred to as Wide crosses. The cereal triticale is a wheat and rye hybrid. The first generation created from the cross was sterile, so the cell division inhibitor colchicine was used to double the number of chromosomes in the cell. Cells with an uneven number of chromosomes are sterile. Failure to produce a hybrid may be due to pre- or post-fertilization incompatibility. If fertilization is possible between two species or genera, the hybrid embryo may abort before maturation. If this does occur the embryo resulting from an interspecific or intergeneric cross can sometimes be rescued and cultured to produce a whole plant. Such a method is referred to as Embryo Rescue. This technique has been used to produce new rice for Africa, an interspecific cross of Asian rice (Oryza sativa) and African rice (Oryza glaberrima). Hybrids may also be produced by a technique called protoplast fusion. In this case protoplasts are fused, usually in an electric field. Viable recombinants can be regenerated in culture. Chemical mutagens like EMS and DMSO, radiation and transposons are used to generate mutants with desirable traits to be bred with other cultivars. Classical plant breeders also generate genetic diversity within a species by exploiting a process called somaclonal variation, which occurs in plants produced from tissue culture, particularly plants derived from callus. Induced polyploidy, and the addition or removal of chromosomes using a technique called chromosome engineering also found uses. When a desirable trait has been bred into a species, a number of crosses to the favoured parent are made to make the new plant as similar as the parent as possible. Returning to the example of the mildew resistant pea being crossed with a high-yielding but susceptible pea, to make the mildew resistant progeny of the cross most like the high-yielding parent, the progeny will be crossed back to that parent for several generations (See backcrossing ). This process removes most of the genetic contribution of the mildew resistant parent. Classical breeding is therefore a cyclical process. It should be noted that with classical breeding techniques, the breeder does not know exactly what genes have been introduced to the new cultivars. Some scientists therefore argue that plants produced by classical breeding methods should undergo the same safety testing regime as genetically modified plants. There have been instances where plants bred using classical techniques have been unsuitable for human consumption, for example the poison solanine was accidentally re-introduced into varieties of potato through plant breeding.
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  • 14 Oct 2022
Topic Review
Desert Island
A deserted island or uninhabited island is an island that is not permanently populated by humans. Uninhabited islands are often used in movies or stories about shipwrecked people, and are also used as stereotypes for the idea of "paradise". Some uninhabited islands are protected as nature reserves and some are privately owned. Devon Island in Canada is claimed to be the largest uninhabited island in the world. Small coral atolls or islands usually have no source of fresh water, but at times a fresh water lens (Ghyben–Herzberg lens) can be reached with a well.
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  • 14 Oct 2022
Topic Review
Ordnance Survey
Ordnance Survey (OS) is the national mapping agency for Great Britain. The agency's name indicates its original military purpose (see ordnance and surveying), which was to map Scotland in the wake of the Jacobite rising of 1745. There was also a more general and nationwide need in light of the potential threat of invasion during the Napoleonic Wars. Since 1 April 2015 Ordnance Survey has operated as Ordnance Survey Ltd, a government-owned company, 100% in public ownership. The Ordnance Survey Board remains accountable to the Secretary of State for Business, Energy and Industrial Strategy. It was also a member of the Public Data Group. Paper maps for walkers represent only 5% of OS' annual revenue. They produce digital map data, online route planning and sharing services and mobile apps, plus many other location-based products for business, government and consumers. Ordnance Survey mapping is usually classified as either "large-scale" (in other words, more detailed) or "small-scale". The Survey's large-scale mapping comprises 1:2,500 maps for urban areas and 1:10,000 more generally. (The latter superseded the 1:10,560 "six inches to the mile" scale in the 1950s.) These large scale maps are typically used in professional land-use contexts and were available as sheets until the 1980s, when they were digitised. Small-scale mapping for leisure use includes the 1:25,000 "Explorer" series, the 1:50,000 "Landranger" series and the 1:250,000 road maps. These are still available in traditional sheet form. Ordnance Survey maps remain in copyright for fifty years after their publication. Some of the Copyright Libraries hold complete or near-complete collections of pre-digital OS mapping.
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Topic Review
Thai Highlands
The Thai highlands or Hills of northern Thailand is a mountainous natural region in the north of Thailand. Its mountain ranges are part of the system of hills extending through Laos, Burma, and China and linking to the Himalayas, of which they may be considered foothills. The highlands in the north of Thailand are characterized by a pattern of generally steep hill ranges, intermontane basins and alluvial gorges. Elevations are generally moderate, little above 2,000 metres (6,600 ft) for the highest summits. There is a wide range of elevations though, with floors ranging between 200 and 500 metres (660 and 1,640 ft) above sea level. Towards the Lao border, the divide to the Mekong basin becomes higher with peaks occasionally rising above 1,500 metres (4,900 ft) and streams flowing in narrow steep valleys. The climate is typical of tropical mountains with clearly delineated wet and dry seasons. Winter temperatures can be cool with frosts occurring most years at higher elevations, but no snow even on the highest peaks. The region of the Thai Highlands encompasses the nine administrative provinces of northern Thailand, based on the six-region system, as well as parts of Tak and Sukhothai Provinces. Some areas of the highlands are sparsely populated.
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  • 14 Oct 2022
Topic Review
Yana, India
Yana is a village located in forests of the Sirsi and Kumta Uttara Kannada district of Karnataka, India which is known for the unusual karst rock formations. It is located in the Sahyadri mountain range of the Western Ghats, about 60 kilometres (37 mi) from Karwar port, 39 kilometres (24 mi) from Sirsi, and 31 kilometres (19 mi) from Kumta. Yana is one of the wettest villages in the world. It is the cleanest village in Karnataka, and the second cleanest village in India . The two unique rock outcrops near the village are a tourist attraction and easily approachable by a small trek through 0.5 kilometres (0.31 mi) of thick forests from the nearest road head. Yana is famous for these two massive rock outcrops known as the Bhairaveshwara Shikhara and the Mohini Shikhara ("Shikhara" means "hill"). The huge rocks are composed of solid black, crystalline karst limestone. Bhairaveshwara Shikhara is 120 metres (390 ft) in height, while the Mohini Shikhara, which is smaller, is 90 metres (300 ft) in height. Yana is also well known as a pilgrimage centre because of the cave temple below the Bhairaveshwara Shikhara where a Swayambhu ("self manifested", or "that which is created by its own accord") linga has been formed. Water drips from the roof over the linga, adding to the sanctity of the place. During Shivaratri here, a car festival is held, along with other festivities. The place and its surrounding hillocks are also known for their evergreen scenic forests.
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  • 14 Oct 2022
Topic Review
An Appeal to Reason
An Appeal to Reason: A Cool Look at Global Warming is a 2008 book by Nigel Lawson. In it, Lawson argues that global warming is happening, but that the science is far from settled. He opposes the scientific consensus as summarized by the IPCC. He also argues that warming will bring both benefits and negative consequences, and that the impact of these changes will be relatively moderate rather than apocalyptic. The book has been rejected by climatologists, including IPCC authors Jean Palutikof and Robert Watson as unscientific. The book was published in the UK and the USA in 2008. It appeared in Spanish translation the following year, published by Gota a gota, the imprint of the think tank FAES.
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  • 14 Oct 2022
Topic Review
Progesterone on Plant Growth and Development
Progesterone is a steroid hormone that is synthesized in the ovaries, placenta, and adrenal glands. The regulation of progesterone on plant growth is concentration-dependent. For example, low progesterone concentrations (0.01–1 μM) stimulate hypocotyl elongation, while high concentrations (100 μM) inhibit hypocotyl growth in Arabidopsis.
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