The Red Mangrove is distributed in costal ecosystems throughout the tropics. It forms a characteristic saline woodland habitat called a mangrove swamp, growing on aerial prop roots which arch above the water level giving stands of this tree a characteristic appearance.
Because they are well adapted to salt water, they thrive where many other plants fail and create their own ecosystems called mangals. The roots act as an ultra-filtration mechanism to exclude up to 97% of the salts from the costal saline water. Salt which does accumulate in the plant concentrates in old leaves which the plant then sheds.
Red mangroves absorb air through pneumatophores, specialised root-like structures which stick up out of the soil like straws for oxygen intake. These “breathing tubes” typically reach heights of up to thirty centimeters, and in other species, over three meters.
Mangroves protect coastal areas from erosion and storm surge during hurricanes. The mangrove’s massive root system is efficient at dissipating wave energy. They slow down tidal water enough that sediment is deposited as the tide comes in, leaving all except fine particles when the tide ebbs. Because of the uniqueness of mangrove ecosystems and the protection against erosion that they provide, they are often the object of conservation programs.
The Axis Mundi describes a point of connection between sky and earth where the four compass directions meet. The symbol originates as a perception that the spot one occupies stands at the center of the world. It is found in cultures utilizing shamanic practices, in major world religions, and in technologically advanced urban centers. Every inhabited region has an Axis Mundi, a place that is sacred above all.
The space serves as a microcosm of order because it is known and settled. Outside the boundaries of the Axis Mundi lie foreign realms that, because they are unfamiliar or not ordered, represent chaos, death or night. From the center one may venture in any of the four cardinal directions, make discoveries, and establish new centers as new realms become known and settled.
A universally told story is that of the healer traversing the Axis Mundi to bring back knowledge from the other world. It may be seen in stories from the Garden of Eden and Jacob’s Ladder to Jack and the Beanstalk and Rapunzel. The stories relate the hero’s descent and ascent through a series of structures that take him from the depths of hell to paradise.
Because the Axis Mundi is an idea that unites a number of concrete images, places and landmarks, no contradiction exists regarding multiple spots as the center. The symbol can operate in a number of locales at once. The ancient Greeks regarded several sites as places of centering, notably the oracle at Delphi, while still maintaining a belief in a cosmic world tree and in Mount Olympus.
The philosophy of biology is a subfield of philosophy of science, which deals with epistemological, metaphysical, and ethical issues in the biological and biomedical sciences. Although philosophers of science and philosophers generally have long been interested in biology, philosophy of biology emerged as an independent field of philosophy in the 1960s and 1970s.
During that time, philosophers of science began paying increasing attention to biology, from the rise of Neodarwinism in the 1930s and 1940s, to the discovery of the structure of DNA in 1953, and to more recent advances in genetic engineering. Other ideas such as the reduction of all life processes to biochemical reactions as well as the incorporation of psychology into a broader neuroscience were also addressed.
Biologists with philosophic interests responded, emphasising the dual nature of the living organism. On the one hand there was the genetic program; the genotype. On the other there was its extended body or soma; the phenotype. In accommodating the more probabilistic and non-universal nature of biological generalisations, it was a help that standard philosophy of science was in the process of accommodating similar aspects of 20th century physics.
Binary opposition is a pair of terms or concepts that are theoretical opposites. In structuralism, a binary opposition is seen as a fundamental organizer of human philosophy, culture, and language. It is one of several influential characteristics or tendencies of Western thought. Typically, one of two opposites assumes a role of dominance over the other. The categorization of binary oppositions is often value-laden and ethnocentric with an illusory order and superficial meaning.
An example of a binary opposition is the presence-absence dichotomy. In much of Western thought, distinguishing between presence and absence is a fundamental element of thought in many cultures. In addition, according to post-structuralist criticisms, presence occupies a position of dominance in Western thought over absence, because absence is traditionally seen as what you get when you take away presence. Had absence been dominant, presence might have been seen as what you get when you take away an absence.
Deconstruction is the event or moment at which a binary opposition is thought to contradict itself and undermine its own authority. Although deconstruction can not explain how a rational basis for defending itself can then be maintained, it has removed any objective basis in structuralism it may have had.
The correspondence between each of the dominant Western concepts such as rational vs. emotional, mind vs. body, thought vs. writing, are claimed to show a tendency of Western thought called logocentrism. The critique of binary oppositions is an important part of post-feminism, post-colonialism, post-anarchism, and critical race theory, which argue that the perceived binary dichotomy between man/woman, civilized/savage, and caucasian/non-caucasian have perpetuated and legitimized Western power structures favoring “civilized” white men.
Genetic testing involves direct examination of the DNA molecule to detemine a person’s ancestry or vulnerabilities to inherited diseases. Genetic testing can provide only limited information about an inherited condition. The test can not determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time.
The results of genetic tests are not always straightforward, which often makes them challenging to interpret and explain. Many of the risks associated with genetic testing involve the emotional, social, or financial consequences of the test results. The possibility of genetic discrimination in employment or insurance is also a concern. In the United States, the use of genetic information is governed by the Genetic Information Nondiscrimination Act.
Direct-to-Consumer genetic testing is a type of genetic test that is accessible directly to the consumer without having to go through a health care professional. Benefits of this type of testing are the accessibility of tests to consumers, promotion of proactive healthcare and the privacy of genetic information.
Some advertising for direct-to-consumer genetic testing has been criticized as conveying an exaggerated and inaccurate message about the connection between genetic information and disease risk, utilizing emotions as a selling factor. Consumers can potentially misinterpret genetic information, causing them to be deluded about their personal health.
Hylomorphism is the theory that all things are a combination of matter and form. Aristotle was one of the first writers to approach the subject of life in a scientific way. Biology was one of his main interests, and there is extensive biological material in his writings. He believed that while matter can exist without form, form cannot exist without matter, and therefore the soul cannot exist without the body.
According to Aristotle, all things in the material universe have both matter and form. The form of a living thing is its soul. There are three kinds of souls: the vegetative soul of plants, which causes them to grow and decay and nourish themselves, but does not cause motion and sensation; the ‘animal soul’ which causes animals to move and feel; and the rational soul which is the source of consciousness and reasoning which Aristotle believed is found only in man.
A properly organized body is already alive simply by virtue of its structure. However, the property of life or soul is something in addition to the body’s structure. The analogy of a car can be used to explain this interpretation. A running car is running not only because of its structure but also because of the activity in its engine. Likewise, a living body is alive not only because of its structure but also because of an additional property. The soul is this additional property, which a properly-organized body needs in order to be alive.
English Ivy is a species native to most of Europe and western Asia. It is an evergreen climbing plant, growing to 100 feet high where suitable surfaces such as trees, cliffs or walls are available. It climbs by means of aerial rootlets which cling to the substrate.
Recent research has used new imaging techniques to analyse the attachment process of English Ivy in detail. It was found that the plant makes initial contact with the object it will climb, which then triggers the second phase, when the plant’s roots change shape to fit the surface of the structure they will climb.
The roots alter their arrangement to increase their area of contact with the surface, then small structures called root hairs grow out from the root, coming into contact with the climbing surface. The plant then excretes a glue to anchor it to the substrate. Finally, the tiny root hairs fit into tiny cavities within the climbing surface. There, they dry out, scrunching into a spiral shape that locks the root hair into place.
English Ivy is considered an invasive species in a number of areas to which it has been introduced. Like other invasive vines, such as kudzu, it can grow to choke out other plants and create “ivy deserts”. State and county sponsored efforts are encouraging the destruction of ivy in forests of the Pacific Northwest. Its sale or import is banned in Oregon. In its mature form, dense ivy can destroy habitat for native wildlife and creates large sections of solid ivy where no other plants can develop.
Alstroemeria, commonly called the Peruvian Lily, is a South American genus of about 50 species of flowering plants. Almost all of the species are restricted to one of two distinct centers of diversity, one in central Chile, the other in eastern Brazil. All are long-lived perennials.
The plants are distinctive vegetatively, with a rootstock consisting of a slender rhizome. Storage roots consist of sausage-like water storing structures suspended from the rhizome by major roots. Each year up to 80 new shoots are produced from the rootstock and each terminates in up to 10 or so flowers.
An interesting morphological trait of Alstroemeria and its relatives is the fact that the leaves are resupinate, that is, they twist from the base so that what appears to be the upper leaf surface is in fact the lower leaf surface. This very unusual botanical feature is easily observed in the leaves on cut flowers from the florist.
The most popular hybrids commonly grown today result from crosses between species from Chile (winter-growing) with species from Brazil (summer-growing). This strategy has overcome the problem of seasonal dormancy and resulted in plants that are evergreen and flower for most of the year.
Bushtits are small birds common in shrubby and woodland habitats. They are a year round resident of the western United States, and do not seem to mind residential areas. Its high pitch twittering contact call is first heard followed by the appearance of a flock ranging up to fifty birds. Members of the group constantly make contact calls to each other that can be described as a short “tsit”.
They typically swoop into an area en mass, bustle around noisily while eating and socializing, and then depart for more insect rich patches of greenery. They glean the vegetation for insects often hanging upside down in their search, gradually moving through the area.
Bushtits build elaborate pendulous nests made up of soft plant material, cobwebs, and man made items like threads and string. They are one of the first birds described to have helpers at the nest, a term used in behavioural ecology and evolutionary biology to describe a social structure in which juveniles and sexually mature adolescents, of either one or both sexes, remain in association with their parents and help them raise subsequent broods or litters.
The birds successfully petitioned for a change-of name when it was brought to their attention that the word “common” had unsavory connotations, a circumstance made particularly agregious by the fact they already had a reputation as noisy little tits. Despite its name, the Bushtit is not a well-endowed member of a prominent American political family.
Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside in globular clusters. Spiral galaxies make up approximately 60% of galaxies in the local Universe. They are mostly found in low-density regions and are rare in the centers of galaxy clusters.
Spiral galaxies are named for the spiral structures that extend from the center into the disk. The spiral arms are sites of ongoing star formation and are brighter than the surrounding disk because of the hot, massive stars that inhabit them. Spiral arms contain a great many young, blue stars, which make the arms so remarkable. Roughly half of all spirals are observed to have an additional component in the form of a bar-like structure, extending from the central bulge, at the ends of which the spiral arms begin.
Our own Milky Way has recently been confirmed to be a barred spiral, although the bar itself is difficult to observe from our position within the Galactic disk. The most convincing evidence for its existence comes from a recent survey, performed by the Spitzer Space Telescope, of stars in the Galactic center.
Bertil Lindblad proposed that the arms represent regions of enhanced density waves that rotate more slowly than the galaxy’s stars and gas. As gas enters a density wave, it gets squeezed and makes new stars, some of which are short-lived blue stars that light the arms.
This idea was developed into density wave theory by C. C. Lin and Frank Shu in 1964. They suggested that the spiral arms were manifestations of spiral density waves, attempting to explain the large-scale structure of spirals in terms of a small-amplitude wave propagating with fixed angular velocity, that revolves around the galaxy at a speed different from that of the galaxy’s gas and stars.