Albinism is a condition that cannot be "cured" per se, but small things can be done to improve the quality of life for those affected. Most importantly to improve vision, protect the eyes from bright lights, and avoid skin damage from sunlight. The extent and success rate of these measures depend on the type of albinism and severity of the symptoms; in particular, people with ocular albinism are likely to have normally-pigmented skin, and thus do not need to take special precautions against skin damage.
Surgical treatment
For the most part, treatment of the eye conditions consists of visual rehabilitation.[citation needed] Surgery is possible on the ocular muscles to decrease nystagmus, strabismus and common refractive errors like astigmatism. Strabismus surgery may improve the appearance of the eyes.[citation needed] Nystagmus-damping surgery can also be performed, to reduce the "shaking" of the eyes back and forth.The effectiveness of all these procedures varies greatly and depends on individual circumstances. More importantly, since surgery will not restore a normal RPE or foveae, surgery will not provide fine binocular vision.[citation needed] In the case of esotropia (the "crossed eyes" form of strabismus), surgery may help vision by expanding the visual field Vision aids.
Glasses and other vision aids, large-print materials and closed captioning, as well as bright but angled reading lights, can help individuals with albinism, even though their vision cannot be corrected completely. Some albinistic people do well using bifocals (with a strong reading lens), prescription reading glasses, and/or hand-held devices such as magnifiers or monoculars.
Contact lenses may be colored to block light transmission through the iris. Some use bioptics, glasses which have small telescopes mounted on, in, or behind their regular lenses, so that they can look through either the regular lens or the telescope. Newer designs of bioptics use smaller light-weight lenses. Some US states allow the use of bioptic telescopes for driving motor vehiclesAlthough still disputed among the experts,[who?] many ophthalmologists recommend the use of glasses from early childhood onward to allow the eyes the best development possible.
Optometrists or ophthalmologists who are experienced in working with low vision patients can recommend various optical aids. Some low-vision clinics provide these aids on trial loan, with instruction in their use.
Sun protection
It is vital that people with albinism use sunscreen when exposed to sunlight to prevent premature skin aging or skin cancer. This poses a problem for those who cannot afford sunscreen, especially in regions with high exposure to sunlight, as in Africa.
Use of sunglasses and hats with wide brims can make the glare outside bearable. Other things that can help people with albinism are avoiding sudden changes of the lighting situation (switching the light on in complete darkness), using dimmable switches and adding tint to car windows or blinds to normal windows. Lights should be yellowish rather than blue[citation needed] and not point towards the usual position of a person with albinism
Sunday, June 29, 2008
Sunday, June 22, 2008
Sporophyte
All land plants, and some algae, have life cycles in which a haploid gametophyte generation alternates with a diploid sporophyte, the generation of a plant or alga that has a double set of chromosomes. A multicellular sporophyte generation or phase is present in the life cycle of all land plants and in some green algae. For common flowering plants (Angiosperms), the sporophyte generation comprises almost their whole life cycle (i.e. whole green plant, roots etc), except phases of small reproductive structures (pollen and ovule).
The sporophyte produces spores (hence the name), by meiosis. These meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of homologous chromosomes. The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte. This cycle is known as alternation of generations or alternation of phases.
n the normal course of events, the zygote and sporophyte will have a full double set of chromosomes again. An exception is when a diploid and haploid gamete fuse, resulting in a triploid sporophyte, which will usually be sterile, as dividing three sets of chromosomes into two halves causes complications.
Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte stage on which the adult sporophyte is dependent on the gametophyte for nutrition. The embryo of the sporophyte develops from the zygote within the female sex organ or archegonium, and in its early development is therefore nurtured by the gametophyte. Because this embryo-nurturing feature of the life cycle is common to all land plants they are known collectively as the Embryophytes.
Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar (isomorphic). An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms (flowering plants) that have survived to the present day. Early land plants had sporophytes that produced identical spores (isosporous or homosporous) but the ancestors of the gymnosperms evolved complex heterosporous life cycles in which the spores producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores.
During the Devonian period several plant groups independently evolved heterospory and subsequently the habit of endospory, in which single megaspores were retained within the sporangia of the parent sporophyte, instead of being freely liberated into the environment as in ancestral exosporous plants. These endosporic megaspores contained within them a miniature multicellular female gametophyte complete with female sex organs or archegonia containing oocytes which were fertilised by free-swimming sperm produced by windborne miniatuarised male gametophytes in the form of pre-pollen. The resulting zygote developed into the next sporophyte generation while still retained within the pre-ovule, the single large female meiospore or megaspore contained in the modified sporangium or nucellus of the parent sporophyte. The evolution of heterospory and endospory were among the earliest steps in the evolution of seeds of the kind produced by gymnosperms and angiosperms today.
The sporophyte produces spores (hence the name), by meiosis. These meiospores develop into a gametophyte. Both the spores and the resulting gametophyte are haploid, meaning they only have one set of homologous chromosomes. The mature gametophyte produces male or female gametes (or both) by mitosis. The fusion of male and female gametes produces a diploid zygote which develops into a new sporophyte. This cycle is known as alternation of generations or alternation of phases.
n the normal course of events, the zygote and sporophyte will have a full double set of chromosomes again. An exception is when a diploid and haploid gamete fuse, resulting in a triploid sporophyte, which will usually be sterile, as dividing three sets of chromosomes into two halves causes complications.
Bryophytes (mosses, liverworts and hornworts) have a dominant gametophyte stage on which the adult sporophyte is dependent on the gametophyte for nutrition. The embryo of the sporophyte develops from the zygote within the female sex organ or archegonium, and in its early development is therefore nurtured by the gametophyte. Because this embryo-nurturing feature of the life cycle is common to all land plants they are known collectively as the Embryophytes.
Most algae have dominant gametophyte generations, but in some species the gametophytes and sporophytes are morphologically similar (isomorphic). An independent sporophyte is the dominant form in all clubmosses, horsetails, ferns, gymnosperms, and angiosperms (flowering plants) that have survived to the present day. Early land plants had sporophytes that produced identical spores (isosporous or homosporous) but the ancestors of the gymnosperms evolved complex heterosporous life cycles in which the spores producing male and female gametophytes were of different sizes, the female megaspores tending to be larger, and fewer in number, than the male microspores.
During the Devonian period several plant groups independently evolved heterospory and subsequently the habit of endospory, in which single megaspores were retained within the sporangia of the parent sporophyte, instead of being freely liberated into the environment as in ancestral exosporous plants. These endosporic megaspores contained within them a miniature multicellular female gametophyte complete with female sex organs or archegonia containing oocytes which were fertilised by free-swimming sperm produced by windborne miniatuarised male gametophytes in the form of pre-pollen. The resulting zygote developed into the next sporophyte generation while still retained within the pre-ovule, the single large female meiospore or megaspore contained in the modified sporangium or nucellus of the parent sporophyte. The evolution of heterospory and endospory were among the earliest steps in the evolution of seeds of the kind produced by gymnosperms and angiosperms today.
Sunday, June 15, 2008
Field-programmable gate array
A field-programmable gate array is a semiconductor device containing programmable logic components called "logic blocks", and programmable interconnects. Logic blocks can be programmed to perform the function of basic logic gates such as AND, and XOR, or more complex combinational functions such as decoders or mathematical functions. In most FPGAs, the logic blocks also include memory elements, which may be simple flip-flops or more complete blocks of memory.
A hierarchy of programmable interconnects allows logic blocks to be interconnected as needed by the system designer, somewhat like a one-chip programmable breadboard. Logic blocks and interconnects can be programmed by the customer or designer, after the FPGA is manufactured, to implement any logical function—hence the name "field-programmable".
FPGAs are usually slower than their application-specific integrated circuit (ASIC) counterparts, cannot handle as complex a design, and draw more power (for any given semiconductor process). But their advantages include a shorter time to market, ability to re-program in the field to fix bugs, and lower non-recurring engineering costs. Vendors can sell cheaper, less flexible versions of their FPGAs which cannot be modified after the design is committed. The designs are developed on regular FPGAs and then migrated into a fixed version that more resembles an ASIC.
"Complex Programmable Logic Device" (CPLDs) are an alternative for simpler designs. They also retain their programming over powerdowns.
To configure ("program") an FPGA or CPLD you specify how you want the chip to work with a logic circuit diagram or a source code using a hardware description language (HDL). The HDL form might be easier to work with when handling large structures because it's possible to just specify them numerically rather than having to draw every piece by hand. On the other hand, schematic entry might allow for a more tight specification of what you want.
Going from schematic/HDL source files to actual configuration: The source files are fed to a software suite from the FPGA/CPLD vendor that through different steps will produce a file. This file is then transferred to the FPGA/CPLD via a serial interface (JTAG) interface or to external memory device like an EEPROM.
A hierarchy of programmable interconnects allows logic blocks to be interconnected as needed by the system designer, somewhat like a one-chip programmable breadboard. Logic blocks and interconnects can be programmed by the customer or designer, after the FPGA is manufactured, to implement any logical function—hence the name "field-programmable".
FPGAs are usually slower than their application-specific integrated circuit (ASIC) counterparts, cannot handle as complex a design, and draw more power (for any given semiconductor process). But their advantages include a shorter time to market, ability to re-program in the field to fix bugs, and lower non-recurring engineering costs. Vendors can sell cheaper, less flexible versions of their FPGAs which cannot be modified after the design is committed. The designs are developed on regular FPGAs and then migrated into a fixed version that more resembles an ASIC.
"Complex Programmable Logic Device" (CPLDs) are an alternative for simpler designs. They also retain their programming over powerdowns.
To configure ("program") an FPGA or CPLD you specify how you want the chip to work with a logic circuit diagram or a source code using a hardware description language (HDL). The HDL form might be easier to work with when handling large structures because it's possible to just specify them numerically rather than having to draw every piece by hand. On the other hand, schematic entry might allow for a more tight specification of what you want.
Going from schematic/HDL source files to actual configuration: The source files are fed to a software suite from the FPGA/CPLD vendor that through different steps will produce a file. This file is then transferred to the FPGA/CPLD via a serial interface (JTAG) interface or to external memory device like an EEPROM.
Sunday, June 08, 2008
Ultra Music Festival
Ultra Music Festival is an outdoor electronic music event held annually in Miami, Florida during the Winter Music Conference which occurs annually during the month of March. It is a 2-day event (although it was a 1-day event until 2007) that takes place across 12 different stages featuring over 200 artists, DJs, producers and promoters.
From 2001 to 2005, UMF was held outdoors in Bayfront Park, Miami. The first two UMFs (1999, & 2000) were actually held on South Beach in Miami Beach, however UMF attendance exceeded the possible beach permits and was subsequently moved to the venue of Bayfront Park. The top DJs and artists of the evening perform in the amphitheater designed to hold thousands of attendees. There is a second main stage (called the 'Sound stage') and 10 other specialized music areas scattered throughout the park featuring Drum and Bass, House, Techno, Electro, Breakbeats, Trance, and other various styles of electronic music.
In 2005 the concert was so popular that it sold out. With the festival growing so big, in 2006 the Miami event had been moved to an even bigger venue, Bicentennial Park, next door to its past home. In 2007, with Winter Music Conference in full swing, Ultra Music Festival had its first 2-Day Event held at Bicentennial Park with a record breaking 50,000+ electronic music fans. Ultra Music Festival celebrated its 10th anniversary on Friday, March 28th and Saturday March 29th, 2008, where an announcement was made that the festival had set a new City of Miami record for the number of tickets sold at a single event.
Ultra Music Festival, in association with Ultra Records, produces an event in New York City's Central Park called ULTRA:NY, which also sold out in 2005. The success has brought Ultra:NY back for a second year.
From 2001 to 2005, UMF was held outdoors in Bayfront Park, Miami. The first two UMFs (1999, & 2000) were actually held on South Beach in Miami Beach, however UMF attendance exceeded the possible beach permits and was subsequently moved to the venue of Bayfront Park. The top DJs and artists of the evening perform in the amphitheater designed to hold thousands of attendees. There is a second main stage (called the 'Sound stage') and 10 other specialized music areas scattered throughout the park featuring Drum and Bass, House, Techno, Electro, Breakbeats, Trance, and other various styles of electronic music.
In 2005 the concert was so popular that it sold out. With the festival growing so big, in 2006 the Miami event had been moved to an even bigger venue, Bicentennial Park, next door to its past home. In 2007, with Winter Music Conference in full swing, Ultra Music Festival had its first 2-Day Event held at Bicentennial Park with a record breaking 50,000+ electronic music fans. Ultra Music Festival celebrated its 10th anniversary on Friday, March 28th and Saturday March 29th, 2008, where an announcement was made that the festival had set a new City of Miami record for the number of tickets sold at a single event.
Ultra Music Festival, in association with Ultra Records, produces an event in New York City's Central Park called ULTRA:NY, which also sold out in 2005. The success has brought Ultra:NY back for a second year.
Monday, June 02, 2008
Human circulatory system
The main components of the human circulatory system are the heart, the blood, and the blood vessels. The circulatory system includes: the pulmonary circulation, a "loop" through the lungs where blood is oxygenated; and the systemic circulation, a "loop" through the rest of the body to provide oxygenated blood. An average adult contains five to six quarts (roughly 4.7 to 5.7 liters) of blood, which consists of plasma that contains red blood cells, white blood cells, and platelets.
Two types of fluids move through the circulatory system: blood and lymph. The blood, heart, and blood vessels form the cardiovascular system. The lymph, lymph nodes, and lymph vessels form the lymphatic system. The cardiovascular system and the lymphatic system collectively make up the circulatory system.
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