Econstudentlog

Wikipedia articles of interest

i. Planetary habitability (featured).

Planetary habitability is the measure of a planet‘s or a natural satellite‘s potential to develop and sustain life. Life may develop directly on a planet or satellite or be transferred to it from another body, a theoretical process known as panspermia. As the existence of life beyond Earth is currently uncertain, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favourable to life’s flourishing—in particular those factors that have sustained complex, multicellular organisms and not just simpler, unicellular creatures. Research and theory in this regard is a component of planetary science and the emerging discipline of astrobiology.

An absolute requirement for life is an energy source, and the notion of planetary habitability implies that many other geophysical, geochemical, and astrophysical criteria must be met before an astronomical body can support life. In its astrobiology roadmap, NASA has defined the principal habitability criteria as “extended regions of liquid water, conditions favourable for the assembly of complex organic molecules, and energy sources to sustain metabolism.”[1]

In determining the habitability potential of a body, studies focus on its bulk composition, orbital properties, atmosphere, and potential chemical interactions. Stellar characteristics of importance include mass and luminosity, stable variability, and high metallicity. Rocky, terrestrial-type planets and moons with the potential for Earth-like chemistry are a primary focus of astrobiological research, although more speculative habitability theories occasionally examine alternative biochemistries and other types of astronomical bodies.”

The article has a lot of stuff – if you’re the least bit interested (and if you are human and alive, as well as a complex enough lifeform to even conceptualize questions like these, why wouldn’t you be?) you should go have a look. When analyzing which factors might impact habitability of a system, some might say that we humans are rather constrained by our somewhat limited sample size of planetary systems known to support complex multicellular life, but this doesn’t mean we can’t say anything about this stuff. Even though extreme caution is naturally warranted when drawing conclusions here. Incidentally, although the Earth does support complex life now we would probably be well-advised to remember that this was not always the case, nor will it continue to be the case in the future – here’s one guess at what the Earth will look like in 7 billion years:

Red_Giant_Earth_warm

The image is from this article. Of course living organisms on Earth will be screwed long before this point is reached.

ii. Parity of zero (‘good article’).

Zero is an even number. Apparently a rather long wikipedia article can be written about this fact…

iii. 1907 Tiflis bank robbery (featured).

Not just any bank robbery – guns as well as bombs/grenades were used during the robbery, around 40 people died(!), and the list of names of the people behind the robbery includes the names Stalin and Lenin.

iv. Möbius Syndrome – what would your life be like if you were unable to make facial expressions and unable to move your eyes from side to side? If you want to know, you should ask these people. Or you could of course just start out by reading the article…

v. Book of the Dead (‘good article’).

800px-PinedjemIIBookOfTheDead-BritishMuseum-August21-08

“The Book of the Dead is an ancient Egyptian funerary text, used from the beginning of the New Kingdom (around 1550 BCE) to around 50 BCE.[1] The original Egyptian name for the text, transliterated rw nw prt m hrw[2] is translated as “Book of Coming Forth by Day”.[3] Another translation would be “Book of emerging forth into the Light”. The text consists of a number of magic spells intended to assist a dead person’s journey through the Duat, or underworld, and into the afterlife.

The Book of the Dead was part of a tradition of funerary texts which includes the earlier Pyramid Texts and Coffin Texts, which were painted onto objects, not papyrus. Some of the spells included were drawn from these older works and date to the 3rd millennium BCE. Other spells were composed later in Egyptian history, dating to the Third Intermediate Period (11th to 7th centuries BCE). A number of the spells which made up the Book continued to be inscribed on tomb walls and sarcophagi, as had always been the spells from which they originated. The Book of the Dead was placed in the coffin or burial chamber of the deceased.

There was no single or canonical Book of the Dead. The surviving papyri contain a varying selection of religious and magical texts and vary considerably in their illustration. Some people seem to have commissioned their own copies of the Book of the Dead, perhaps choosing the spells they thought most vital in their own progression to the afterlife. […]

A Book of the Dead papyrus was produced to order by scribes. They were commissioned by people in preparation for their own funeral, or by the relatives of someone recently deceased. They were expensive items; one source gives the price of a Book of the Dead scroll as one deben of silver,[50] perhaps half the annual pay of a labourer.[51] Papyrus itself was evidently costly, as there are many instances of its re-use in everyday documents, creating palimpsests. In one case, a Book of the Dead was written on second-hand papyrus.[52]

Most owners of the Book of the Dead were evidently part of the social elite; they were initially reserved for the royal family, but later papyri are found in the tombs of scribes, priests and officials. Most owners were men, and generally the vignettes included the owner’s wife as well. Towards the beginning of the history of the Book of the Dead, there are roughly 10 copies belonging to men for every one for a woman. However, during the Third Intermediate Period, 2/3 were for women; and women owned roughly a third of the hieratic paypri from the Late and Ptolemaic Periods.[53]

The dimensions of a Book of the Dead could vary widely; the longest is 40m long while some are as short as 1m. They are composed of sheets of papyrus joined together, the individual papyri varying in width from 15 cm to 45 cm.”

vi. Volcanic ash (‘good article’).

800px-MountRedoubtEruption

Volcanic ash consists of fragments of pulverized rock, minerals and volcanic glass, created during volcanic eruptions, less than 2 mm (0.079 in) in diameter.[1] The term volcanic ash is also often loosely used to refer to all explosive eruption products (correctly referred to as tephra), including particles larger than 2mm. Volcanic ash is formed during explosive volcanic eruptions when dissolved gases in magma expand and escape violently into the atmosphere. The force of the escaping gas shatters the magma and propels it into the atmosphere where it solidifies into fragments of volcanic rock and glass. Ash is also produced when magma comes into contact with water during phreatomagmatic eruptions, causing the water to explosively flash to steam leading to shattering of magma. Once in the air, ash is transported by wind up to thousands of kilometers away. […]

Physical and chemical characteristics of volcanic ash are primarily controlled by the style of volcanic eruption.[8] Volcanoes display a range of eruption styles which are controlled by magma chemistry, crystal content, temperature and dissolved gases of the erupting magma and can be classified using the Volcanic Explosivity Index (VEI). Effusive eruptions (VEI 1) of basaltic composition produce <105 m3 of ejecta, whereas extremely explosive eruptions (VEI 5+) of rhyolitic and dacitic composition can inject large quantities (>109 m3) of ejecta into the atmosphere. Another parameter controlling the amount of ash produced is the duration of the eruption: the longer the eruption is sustained, the more ash will be produced. […]

The types of minerals present in volcanic ash are dependent on the chemistry of the magma from which it was erupted. Considering that the most abundant elements found in magma are silica (SiO2) and oxygen, the various types of magma (and therefore ash) produced during volcanic eruptions are most commonly explained in terms of their silica content. Low energy eruptions of basalt produce a characteristically dark coloured ash containing ~45 – 55% silica that is generally rich in iron (Fe) and magnesium (Mg). The most explosive rhyolite eruptions produce a felsic ash that is high in silica (>69%) while other types of ash with an intermediate composition (e.g. andesite or dacite) have a silica content between 55-69%.

The principal gases released during volcanic activity are water, carbon dioxide, sulfur dioxide, hydrogen, hydrogen sulfide, carbon monoxide and hydrogen chloride.[9] These sulfur and halogen gases and metals are removed from the atmosphere by processes of chemical reaction, dry and wet deposition, and by adsorption onto the surface of volcanic ash. […]

Ash particles are incorporated into eruption columns as they are ejected from the vent at high velocity. The initial momentum from the eruption propels the column upwards. As air is drawn into the column, the bulk density decreases and it starts to rise buoyantly into the atmosphere.[6] At a point where the bulk density of the column is the same as the surrounding atmosphere, the column will cease rising and start moving laterally. Lateral dispersion is controlled by prevailing winds and the ash may be deposited hundreds to thousands of kilometres from the volcano, depending on eruption column height, particle size of the ash and climatic conditions (especially wind direction and strength and humidity).[25]

Ash fallout occurs immediately after the eruption and is controlled by particle density. Initially, coarse particles fall out close to source. This is followed by fallout of accretionary lapilli, which is the result of particle agglomeration within the column.[26] Ash fallout is less concentrated during the final stages as the column moves downwind. This results in an ash fall deposit which generally decreases in thickness and grain size exponentially with increasing distance from the volcano.[27] Fine ash particles may remain in the atmosphere for days to weeks and be dispersed by high-altitude winds.”

If you’re interested in this kind of stuff (the first parts of the article), Press’ and Siever’s textbook Earth, which I read last summer (here’s one relevant post), is pretty good. There’s a lot of stuff in the article about how this stuff impacts humans and human infrastructure though I decided against including any of that stuff here – if you’re curious, go have a look.

vii. Kingdom of Mysore (featured).

“The Kingdom of Mysore was a kingdom of southern India, traditionally believed to have been founded in 1399 in the vicinity of the modern city of Mysore. The kingdom, which was ruled by the Wodeyar family, initially served as a vassal state of the Vijayanagara Empire. With the decline of the Vijayanagara Empire (c.1565), the kingdom became independent. The 17th century saw a steady expansion of its territory and, under Narasaraja Wodeyar I and Chikka Devaraja Wodeyar, the kingdom annexed large expanses of what is now southern Karnataka and parts of Tamil Nadu to become a powerful state in the southern Deccan.

The kingdom reached the height of its military power and dominion in the latter half of the 18th century under the de facto ruler Haider Ali and his son Tipu Sultan. During this time, it came into conflict with the Marathas, the British and the Nizam of Hyderabad, which culminated in the four Anglo-Mysore wars. Success in the first two Anglo-Mysore wars was followed by defeat in the third and fourth. Following Tipu’s death in the fourth war of 1799, large parts of his kingdom were annexed by the British, which signalled the end of a period of Mysorean hegemony over southern Deccan. The British restored the Wodeyars to their throne by way of a subsidiary alliance and the diminished Mysore was transformed into a princely state. The Wodeyars continued to rule the state until Indian independence in 1947, when Mysore acceded to the Union of India. […]

The vast majority of the people lived in villages and agriculture was their main occupation. The economy of the kingdom was based on agriculture. Grains, pulses, vegetables and flowers were cultivated. Commercial crops included sugarcane and cotton. The agrarian population consisted of landlords (gavunda, zamindar, heggadde) who tilled the land by employing a number of landless labourers, usually paying them in grain. Minor cultivators were also willing to hire themselves out as labourers if the need arose.[73] It was due to the availability of these landless labourers that kings and landlords were able to execute major projects such as palaces, temples, mosques, anicuts (dams) and tanks.[74] Because land was abundant and the population relatively sparse, no rent was charged on land ownership. Instead, landowners paid tax for cultivation, which amounted to up to one-half of all harvested produce.[74]

Tipu Sultan is credited to have founded state trading depots in various locations of his kingdom. In addition, he founded depots in foreign locations such as Karachi, Jeddah and Muscat, where Mysore products were sold.[75] During Tipu’s rule French technology was used for the first time in carpentry and smithy, Chinese technology was used for sugar production, and technology from Bengal helped improve the sericulture industry.[76] State factories were established in Kanakapura and Taramandelpeth for producing cannons and gunpowder respectively. The state held the monopoly in the production of essentials such as sugar, salt, iron, pepper, cardamom, betel nut, tobacco and sandalwood, as well as the extraction of incense oil from sandalwood and the mining of silver, gold and precious stones. Sandalwood was exported to China and the Persian Gulf countries and sericulture was developed in twenty-one centres within the kingdom.[77]

This system changed under the British, when tax payments were made in cash, and were used for the maintenance of the army, police and other civil and public establishments. A portion of the tax was transferred to England as the “Indian tribute”.[78] Unhappy with the loss of their traditional revenue system and the problems they faced, peasants rose in rebellion in many parts of south India.[79] […]

Prior to the 18th century, the society of the kingdom followed age-old and deeply established norms of social interaction between people. Accounts by contemporaneous travellers indicate the widespread practice of the Hindu caste system and of animal sacrifices during the nine day celebrations (called Mahanavami).[101] Later, fundamental changes occurred due to the struggle between native and foreign powers. Though wars between the Hindu kingdoms and the Sultanates continued, the battles between native rulers (including Muslims) and the newly arrived British took centre stage.[61] The spread of English education, the introduction of the printing press and the criticism of the prevailing social system by Christian missionaries helped make the society more open and flexible. The rise of modern nationalism throughout India also had its impact on Mysore.[102]

With the advent of British power, English education gained prominence in addition to traditional education in local languages. These changes were orchestrated by Lord Elphinstone, the governor of the Madras Presidency. […]

Social reforms aimed at removing practices such as sati and social discrimination based upon untouchability, as well as demands for the emancipation of the lower classes, swept across India and influenced Mysore territory.[106] In 1894, the kingdom passed laws to abolish the marriage of girls below the age of eight. Remarriage of widowed women and marriage of destitute women was encouraged, and in 1923, some women were granted the permission to exercise their franchise in elections.[107] There were, however, uprisings against British authority in the Mysore territory, notably the Kodagu uprising in 1835 (after the British dethroned the local ruler Chikkaviraraja) and the Kanara uprising of 1837.”

Not from wikipedia, but a link to this recent post by Razib Khan seems relevant to include here.

July 14, 2013 - Posted by | astronomy, biology, Geology, history, mathematics, medicine, wikipedia

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