Wednesday, November 12, 2008
Manicouagan Reservoir
Monday, November 03, 2008
Morphology
The term morphology in biology refers to the outward appearance (shape, structure, colour, pattern) of an organism or taxon and its component parts. This is in contrast to physiology, which deals primarily with function.
Also in use is the term "gross morphology", which refers to the prominent or principal aspects of an organism or taxon's morphology. A description of an organism's gross morphology would include, for example, its overall shape, overall colour, main markings etc. but not finer details.
Most taxa differ morphologically from other taxa. Typically, closely related taxa differ much less than more distantly related ones, but there are exceptions to this. Cryptic species are species which look very similar, or perhaps even outwardly identical, but are reproductively isolated. Conversely, sometimes unrelated taxa acquire similar appearance through convergent evolution or even through mimicry. A further problem with relying on morphological data is that what may appear, morphologically speaking, to be two distinct species, may in fact be shown by DNA analysis to be a single species.
Thursday, October 30, 2008
Brain tumors in infants and children
In 2000 approximately 2.76 children per 100,000 were affected by a CNS tumor in the United States. This rate has been increasing and by 2005 was 3.0 children per 100,000.[citation needed] This is approximately 2,500-3,000 pediatric brain tumors occurring each year in the US. The tumor incidence is increasing by about 2.7% per year. The CNS cancer survival rate in children is approximately 60%. However, this rate varies with the age of onset (younger has higher mortality) and cancer type.
In children under 2, about 70% of brain tumors are medulloblastoma, ependymoma, and low-grade glioma. Less commonly, and seen usually in infants, are teratoma and atypical teratoid rhabdoid tumor. Germ cell tumors, including teratoma, make up just 3% of pediatric primary brain tumors, but the worldwide incidence varies significantly.
Tuesday, October 21, 2008
Famine food
A famine food or poverty food is any inexpensive or readily-available foodstuff used to nourish people in times of extreme poverty or starvation, as during a war or famine. Quite often, the food is thereafter strongly associated with the hardship under which it was eaten, and is therefore socially downplayed or rejected as a food source in times of relative plenty.
Foods associated with famine need not be nutritionally deficient. A number of famine foods are quite nutritious—thus their use to nourish and ward off hunger. However, such foodstuffs usually offer limited variability, may tend toward the less savoury end of the spectrum, yet are still consumed in large amounts and for long periods of time because of the nutritional duress. As such, people often remain averse to them long after the immediate need to consume them has subsided. That remains the case even if such foodstuffs might otherwise constitute a healthy part of a more comprehensive diet.
Monday, October 13, 2008
W-CDMA
W-CDMA (Wideband Code Division Multiple Access) is a type of 3G cellular network. W-CDMA is the higher speed transmission protocol used in the Japanese FOMA system and in the UMTS system, a third generation follow-on to the 2G GSM networks deployed worldwide.
More technically, W-CDMA is a wideband spread-spectrum mobile air interface that utilizes the direct-sequence spread spectrum method of asynchronous code division multiple access to achieve higher speeds and support more users compared to the implementation of time division multiplexing (TDMA) used by 2G GSM networks.
Monday, September 29, 2008
Bluetooth 3.0
The next version of Bluetooth after v2.1, code-named Seattle (the version number of which is TBD) has many of the same features, but is most notable for plans to adopt ultra-wideband (UWB) radio technology. This will allow Bluetooth use over UWB radio, enabling very fast data transfers of up to 480 Mbit/s, while building on the very low-power idle modes of Bluetooth.
Tuesday, September 23, 2008
IP address
An Internet Protocol (IP) address is a numerical identification (logical address) that is assigned to devices participating in a computer network utilizing the Internet Protocol for communication between its nodes. Although IP addresses are stored as binary numbers, they are usually displayed in human-readable notations, such as 192.168.100.1 (for IPv4), and 2001:db8:0:1234:0:567:1:1 (for IPv6). The role of the IP address has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."
The original designers of TCP/IP defined an IP address as a 32-bit number and this system, now named Internet Protocol Version 4 (IPv4), is still in use today. However, due to the enormous growth of the Internet and the resulting depletion of the address space, a new addressing system (IPv6), using 128 bits for the address, was developed (RFC 1883).
The Internet Protocol also has the task of routing data packets between networks, and IP addresses specify the locations of the source and destination nodes in the topology of the routing system. For this purpose, some of the bits in an IP address are used to designate a subnetwork. (In CIDR notation, the number of bits used for the subnet follows the IP address. E.g. 192.168.100.1/16) An IP address can be private, for use on a LAN, or public, for use on the Internet or other WAN.
Early specifications intended IP addresses to be uniquely assigned to a particular computer or device.[citation needed] However, it was found that this was not always necessary as private networks developed and address space needed to be conserved (IPv4 address exhaustion). RFC 1918 specifies private address spaces that may be reused by anyone; today, such private networks typically access the Internet through Network Address Translation (NAT). In addition, technologies such as anycast addressing have been developed to allow multiple hosts at the same IP address but in different portions of the Internet to service requests by network clients.
The Internet Assigned Numbers Authority (IANA) manages the global IP address space. IANA works in cooperation with five Regional Internet Registries (RIRs) to allocate IP address blocks to Local Internet Registries (Internet service providers) and other entities.
Monday, September 08, 2008
Armour
Armour (or armor) is protective covering, most commonly manufactured from metals, to prevent damage from being inflicted to an individual or a vehicle through use of direct contact weapons or projectiles, usually during combat.
While early armour tended to be worn as clothing intended to defend its wearer during combat between armed forces, armour has been used throughout recorded history, manufactured from a variety of materials, non-metallic and metallic. For much of military history the manufacture of metal armour in Europe has dominated the technology and employment of armour. Its production has been influential in the evolving industrial revolution, and influenced commercial development of metallurgy and engineering.
Armour production was a cause of the development of many important technologies of the Ancient World, including wood lamination, mining, metal refining, vehicle manufacture (chariot), leather processing, and later decorative metal working.
Armour was commonly used to protect only soldiers, foot and mounted. Starting with the rudimentary leather protection, the personal armour evolved to mail and full plated suit of armour. Armour was the single most influential factor in the development of firearms that revolutionised warfare, and has returned in the shape of armoured fighting vehicles in the attempt to enable ground troops to breach field defences unscathed. Sailors and pilots have also benefited from use of armour, with armoured warships dominating naval warfare until the building of the aircraft carriers.
War animals such as elephants and war horses, have also benefited from armour, the application for the later called barding. Armour has also been produced for hunting dogs that hunt dangerous game, such as boars.
Tuesday, September 02, 2008
Female Interest and Body Language
Women commonly display interest in men via sexual cues. These serve to entice men to approach them. Some of the cues to signal female interest include: the parade, echoing and mirroring, room encompassing glance, pointing, leg crossing, the pointing knee, neck touching, head tilt, shoulder shrugs, rotation of the pelvis, showing wrists, skirt hike, laughing and smiling, the tap, forehead bow, eye contact, touching, and childlike playfulness and proximity to name many.
Monday, August 25, 2008
Disk access and file systems
Access to files stored on disks is a central feature of all operating systems. Computers store data on disks using files, which are structured in specific ways in order to allow for faster access, higher reliability, and to make better use out of the drive's available space. The specific way files are stored on a disk is called a file system, and enables files to have names and attributes. It also allows them to be stored in a hierarchy of directories or folders arranged in a directory tree.
Early operating systems generally supported a single type of disk drive and only one kind of file system. Early file systems were limited in their capacity, speed, and in the kinds of file names and directory structures they could use. These limitations often reflected limitations in the operating systems they were designed for, making it very difficult for an operating system to support more than one file system.
While many simpler operating systems support a limited range of options for accessing storage systems, more modern operating systems like UNIX and Linux support a technology known as a virtual file system or VFS. A modern operating system like UNIX supports a wide array of storage devices, regardless of their design or file systems to be accessed through a common application programming interface (API). This makes it unnecessary for programs to have any knowledge about the device they are accessing. A VFS allows the operating system to provide programs with access to an unlimited number of devices with an infinite variety of file systems installed on them through the use of specific device drivers and file system drivers.
A connected storage device such as a hard drive will be accessed through a device driver. The device driver understands the specific language of the drive and is able to translate that language into a standard language used by the operating system to access all disk drives. On UNIX this is the language of block devices.
When the kernel has an appropriate device driver in place, it can then access the contents of the disk drive in raw format, which may contain one or more file systems. A file system driver is used to translate the commands used to access each specific file system into a standard set of commands that the operating system can use to talk to all file systems. Programs can then deal with these file systems on the basis of filenames, and directories/folders, contained within a hierarchical structure. They can create, delete, open, and close files, as well as gather various information about them, including access permissions, size, free space, and creation and modification dates.
Various differences between file systems make supporting all file systems difficult. Allowed characters in file names, case sensitivity, and the presence of various kinds of file attributes makes the implementation of a single interface for every file system a daunting task. While UNIX and Linux systems generally have support for a wide variety of file systems, proprietary operating systems such a Microsoft Windows tend to limit the user to using a single file system for each task. For example the Windows operating system can only be installed on FAT or NTFS, and CDs and DVDs can only be recorded using UDF or ISO 9660
Tuesday, August 19, 2008
Demographic profile
A demographic or demographic profile is a term used in marketing and broadcasting, to describe a demographic grouping or a market segment. This typically involves age bands (as teenagers do not wish to purchase denture fixant), social class bands (as the rich may want different products than middle and lower classes and may be willing to pay more) and gender (partially because different physical attributes require different hygiene and clothing products, and partially because of the male/female mindsets).
A demographic profile can be used to determine when and where advertising should be placed so as to achieve maximum results. In all such cases, it is important that the advertiser get the most results for their money, and so careful research is done to match the demographic profile of the target market to the demographic profile of the advertising medium.
A good way to figure out the intended demographic of a television show, TV channel, or magazine is to study the ads that accompany it. For example, in the United States the television program The Price is Right most frequently airs from 11 a.m. to Noon. The commercials on it (besides the use of product placement in the show itself) are often for things like arthritis pain relievers and diapers. This indicates that the target demographics are senior citizens and parents with young children, both of which would be home at that time of day and see that show. Another example would be MTV, for it has many ads with digital audio players indicating that the channel is targeted to young adults and teenagers and/or fans of music.
Monday, August 11, 2008
DivX
DivX is a brand name of products created by DivX, Inc. (formerly DivXNetworks, Inc.), including the DivX Codec which has become popular due to its ability to compress lengthy video segments into small sizes while maintaining relatively high visual quality. The DivX codec uses lossy MPEG-4 Part 2 compression, also known as MPEG-4 ASP, where quality is balanced against file size for utility. It is one of several codecs commonly associated with "ripping", whereby audio and video multimedia are transferred to a hard disk and transcoded. Many newer "DivX Certified" DVD players are able to play DivX encoded movies, although the Qpel and global motion compensation features are often omitted to reduce processing requirements. They are also excluded from the base DivX encoding profiles for compatibility reasons.
The "DivX" brand is distinct from "DIVX" (Digital Video Express), an unrelated attempt by the U.S. retailer Circuit City to develop a DVD rental system requiring special discs and players. The winking emoticon in the early "DivX ;-)" codec name was a tongue-in-cheek reference to the failed DIVX system. The DivX company then adopted the name of the popular DivX ;-) codec (which was not created by them), dropped the smiley and released DivX 4.0, which was actually the first DivX version (that is, DivX ;-) and DivX are two different things created by different people, the former is not an older version of the latter). The DivX name is its trademark. It is pronounced DIV-ex.
Monday, August 04, 2008
Sporophyte
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.
Monday, July 28, 2008
The notion of freedom
It was possible to detect human advances, as well as human regressions to an earlier state. In Hegel’s view, if something existed, it was rational. If it passed out of existence, that was because it had become irrational. This contained a very important idea, however poorly expressed, namely that history was not a fluke of fate (a kismet) but that it could be rationally understood ,’’ at least in principle.
Monday, July 21, 2008
Old Kingdom
The term itself was coined by nineteenth century historians and the distinction between the Old Kingdom and the Early Dynastic Period is not one which would have been recognized by Ancient Egyptians. Not only was the last king of the Early Dynastic Period related to the first two kings of the Old Kingdom, but the 'capital', the royal residence, remained at Ineb-Hedg, the Ancient Egyptian name for Memphis. The basic justification for a separation between the two periods is the revolutionary change in architecture accompanied by the effects on Egyptian society and economy of large-scale building projects.
The Old Kingdom is most commonly regarded as spanning the period of time when Egypt was ruled by the Third Dynasty through to the Sixth Dynasty (2686 BC – 2134 BC). Many Egyptologists also include the Memphite Seventh and Eighth Dynasties in the Old Kingdom as a continuation of the administration centralized at Memphis. The Old Kingdom was followed by a period of disunity and relative cultural decline referred to by Egyptologists as the First Intermediate Period.
The royal capital of Egypt during the Old Kingdom was located at Memphis, where Djoser established his court. The Old Kingdom is perhaps best known, however, for the large number of pyramids, which were constructed at this time as pharaonic burial places. For this reason, the Old Kingdom is frequently referred to as "the Age of the Pyramids."
Tuesday, July 15, 2008
Phenotypic variation
The interaction between genotype and phenotype has often been conceptualized by the following relationship:
genotype + environment → phenotype
A slightly more nuanced version of the relationships is:
genotype + environment + random-variation → phenotype
Genotypes often have great flexibility in the modification and expression of phenotypes, in many organisms these phenotypes are very different under varying environmental conditions. The plant Hieracium umbellatum is found growing in two different habitats in Sweden. One habitat is rocky, sea-side cliffs, where the plants are bushy with broad leaves and expanded inflorescences; the other is among sand dunes where the plants grow prostrate with narrow leaves and compact inflorescences. These habitats alternate along the coast of Sweden and the habitat that the seeds of Hieracium umbellatum land in, determine the phenotype that grows.[4]
An example of random variation in Drosophila flies is the number of ommatidia, which may vary (randomly) between left and right eyes in a single individual as much as they do between different genotypes overall, or between clones raised in different environments.
A phenotype is any detectable characteristic of an organism (i.e., structural, biochemical, physiological, and behavioral) determined by an interaction between its genotype and environment (of this distinction).
According to the autopoietic notion of living systems by Humberto Maturana, the phenotype is epigenetically being constructed throughout ontogeny, and we as observers make the distinctions that define any particular trait at any particular state of the organism's life cycle.
The idea of the phenotype has been generalized by Richard Dawkins in The Extended Phenotype to mean all the effects a gene has on the outside world that may influence its chances of being replicated. These can be effects on the organism in which the gene resides, the environment, or other organisms. For instance, a beaver dam might be considered a phenotype of beaver genes, the same way beaver's powerful incisor teeth are phenotype expressions of their genes. Dawkins also cites the effect of an organism on the behaviour of another organism, such as the devoted nurturing of a cuckoo by a parent clearly of a different species as an example of the extended phenotype.
The concept of phenotype can be extended to variations below the level of the gene that affect an organism's fitness. For example, silent mutations that do not change the corresponding amino acid sequence of a gene may change the frequency of guanine-cytosine base pairs (GC content). These base pairs have a higher thermal stability (melting point, see also DNA-DNA hybridization) than adenine-thymine, a property that might convey, among organisms living in high-temperature environments, a selective advantage on variants enriched in GC content.
Sunday, July 06, 2008
Oldowan
Sometimes Oldowan tools are called "core tools," "pebble tools," or "choppers." These terms have generally been abandoned because they are not accurate or apply to more than one tradition. Oldowan tools are not necessarily cores, pebbles, or bifaces, and comprise more than hand-axes; moreover, those terms could apply equally to Acheulean tools, whereas "Oldowan" is more specific.
Oldowan tool use is estimated to have begun about 2.5 million years ago (mya), lasting to as late as 0.5 mya. For about 1 million years exclusively Oldowan sites are found. After 1.5 mya. Acheulean sites make their appearance in the archaeological record, but this does not mean Oldowan sites are no longer found. It is thought that Oldowan tools were produced by several species of hominins ranging from Australopithecus to early Homo.
"Oldowan" therefore does not properly refer to a culture, but to a very simple tradition of tool manufacture that was in use for a long time.
Sunday, June 29, 2008
Gene
Colloquially, the term gene is often used to refer to an inheritable trait which is usually accompanied by a phenotype as in ("tall genes" or "bad genes") -- the proper scientific term for this is allele.
In cells, genes consist of a long strand of DNA that contains a promoter, which controls the activity of a gene, and coding and non-coding sequence. Coding sequence determines what the gene produces, while non-coding sequence can regulate the conditions of gene expression. When a gene is active, the coding and non-coding sequence is copied in a process called transcription, producing an RNA copy of the gene's information. This RNA can then direct the synthesis of proteins via the genetic code. But some RNAs are used directly, for example as part of the ribosome. These molecules resulting from gene expression, whether RNA or protein, are known as gene products.
Genes often contain regions that do not encode products, but regulate gene expression. The genes of eukaryotic organisms can contain regions called introns that are removed from the messenger RNA in a process called splicing. The regions encoding gene products are called exons. In eukaryotes, a single gene can encode multiple proteins, which are produced through the creation of different arrangements of exons through alternative splicing. In prokaryotes (bacteria and archaea), introns are less common and genes often contain a single uninterrupted stretch of DNA, called a cistron, that codes for a product. Prokaryotic genes are often arranged in groups called operons with promoter and operator sequences that regulate transcription of a single long RNA. This RNA contains multiple coding sequences. Each coding sequence is preceded by a Shine-Dalgarno sequence that ribosomes recognize.
The total set of genes in an organism is known as its genome. An organism's genome size is generally lower in prokaryotes, both in number of base pairs and number of genes, than even single-celled eukaryotes. However, there is no clear relationship between genome sizes and complexity in eukaryotic organisms. One of the largest known genomes belongs to the single-celled amoeba Amoeba dubia, with over 670 billion base pairs, some 200 times larger than the human genome. The estimated number of genes in the human genome has been repeatedly revised downward since the completion of the Human Genome Project; current estimates place the human genome at just under 3 billion base pairs and about 20,000–25,000 protein-coding genes, with a article from 2007 giving a number of 20,488 plus perhaps 100 more yet to be discovered. The gene density of a genome is a measure of the number of genes per million base pairs (called a megabase, Mb); prokaryotic genomes have much higher gene densities than eukaryotes. The gene density of the human genome is roughly 12–15 genes per megabase pair.
Albinism
Sunday, June 22, 2008
Embryophyte
Embryophytes developed from complex green algae (Chlorophyta) during the Paleozoic era. The Charales or stoneworts appear to be the best living illustration of that developmental step. These alga-like plants undergo an alternation between haploid and diploid generations (respectively called gametophytes and sporophytes). In the first embryophytes, however, the sporophytes became very different in structure and function, remaining small and dependent on the parent for their entire brief life. Such plants are informally called 'bryophytes'. They include three surviving groups:
- Bryophyta (mosses)
- Anthocerotophyta (hornworts)
- Marchantiophyta (liverworts)
All of the above 'bryophytes' are relatively small and are usually confined to moist environments, relying on water to disperse their spores. Other plants, better adapted to terrestrial conditions, appeared during the Silurian period. During the Devonian period, they diversified and spread to many different land environments, becoming the vascular plants or tracheophytes. Tracheophyta have vascular tissues or tracheids, which transport water throughout the body, and an outer layer or cuticle that resists drying out. In most vascular plants, the sporophyte is the dominant individual, and develops true leaves, stems, and roots, while the gametophyte remains very small.
Many vascular plants, however, still disperse using spores. They include two extant groups:
- Lycopodiophyta (clubmosses)
- Pteridophyta (ferns, whisk ferns, and horsetails)
Other groups, which first appeared towards the end of the Paleozoic era, reproduce using desiccation-resistant capsules called seeds. These groups are accordingly called spermatophytes or seed plants. In these forms, the gametophyte is completely reduced, taking the form of single-celled pollen and ova, while the sporophyte begins its life enclosed within the seed. Some seed plants may even survive in extremely arid conditions, unlike their more water-bound precursors. The seed plants include the following extant groups:
- Cycadophyta (cycads)
- Ginkgophyta (ginkgo)
- Pinophyta (conifers)
- Gnetophyta (gnetae)
- Magnoliophyta (flowering plants)
The first four groups are referred to as gymnosperms, since the embryonic sporophyte is not enclosed until after pollination. In contrast, among the flowering plants or angiosperms, the pollen has to grow a tube to penetrate the seed coat. Angiosperms were the last major group of plants to appear, developing from gymnosperms during the Jurassic period, and then spreading rapidly during the Cretaceous. They are the predominant group of plants in most terrestrial biomes today.
Note that the higher-level classification of plants varies considerably. Some authors have restricted the kingdom Plantae to include only embryophytes, others have given them various names and ranks. The groups listed here are often considered divisions or phyla, but have also been treated as classes, and they are occasionally compressed into as few as two divisions. Some classifications, indeed, consider the term Embryophyta at the superphylum (superdivision) level, and include Land Plants and some Charophyceae in a subkingdom named Streptophyta.
On a microscopic level, embryophyte cells remain very similar to those of green algae. They are eukaryotic, with a cell wall composed of cellulose and plastids surrounded by two membranes. These usually take the form of chloroplasts, which conduct photosynthesis and store food in the form of starch, and characteristically are pigmented with chlorophylls a and b, generally giving them a bright green color. Embryophytes also generally have an enlarged central vacuole or tonoplast, which maintains cell turgor and keeps the plant rigid. They lack flagella and centrioles except in certain gametes.
Sunday, June 15, 2008
Application-specific integrated circuit
In contrast, the 7400 series and 4000 series integrated circuits are logic building blocks that can be wired together for use in many different applications. Intermediate between ASICs and standard products are application specific standard products (ASSPs).
As feature sizes have shrunk and design tools improved over the years, the maximum complexity (and hence functionality) possible in an ASIC has grown from 5,000 gates to over 100 million. Modern ASICs often include entire 32-bit processors, memory blocks including ROM, RAM, EEPROM, Flash and other large building blocks. Such an ASIC is often termed a SoC (System-on-a-chip). Designers of digital ASICs use a hardware description language (HDL), such as Verilog or VHDL, to describe the functionality of ASICs.
Field-programmable gate arrays (FPGA) are the modern day equivalent of 7400 series logic and a breadboard, containing programmable logic blocks and programmable interconnects that allow the same FPGA to be used in many different applications. For smaller designs and/or lower production volumes, FPGAs may be more cost effective than an ASIC design. The Non-recurring engineering cost (the cost to set up the factory to produce a particular ASIC) can run into the millions of dollars.
The general term application specific integrated circuit includes FPGAs, but most designers use ASIC only for non field programmable devices (e.g. standard cell or sea of gates) and make a distinction between ASIC and FPGAs.
Sunday, June 08, 2008
Breakbeat
Breakbeat (sometimes breakbeats or breaks) is a term used to describe a collection of sub-genres of electronic music, usually characterized by the use of a non-straightened 4/4 drum pattern (as opposed to the steady beat of house or trance). These rhythms may be characterised by their intensive use of syncopation and polyrhythms.
In the late 1960s and early 1970s, hip-hop DJs (starting with Kool DJ Herc) began using several breaks (the part of a funk or jazz song in which the music "breaks" to let the rhythm section play unaccompanied) in a row to use as the rhythmic basis for hip-hop songs. Kool DJ Herc's breakbeat style was to play the same record on two turntables and play the break repeatedly by alternating between the two records (letting one play while spinning the second record back to the beginning of the break). This style was copied and improved upon by early hip hop DJs Afrika Bambaataa and Grand Wizard Theodore.[1] This style was extremely popular in clubs and dance halls because the extended breakbeat was the perfect backdrop for breakdancers to show their skills.
Monday, June 02, 2008
Human Systemic circulation
Wednesday, May 28, 2008
Precursors
Ivan Sutherland developed a pointer-based system called Sketchpad in 1963. It used a light-pen to guide the creation and manipulation of objects in engineering drawings.
Tuesday, May 27, 2008
Understanding the Context
* Some activities take place in real-time while others allow for a delayed reply.
* Discussion areas may be public or exist for a particular group of people.
* Information can either be broadcast or targeted at a particular user.
As the technology develops, and users and providers become more proficient, the boundaries between the different Internet services are blurred. For example, email is used in chat rooms, web pages include discussion areas and newsgroups can have files attached.
Each Internet service has its own educational value, risks, and recommended ways of dealing with problems, and these are detailed in the following pages. They are not exhaustive and many apply across Internet services. Schools should consider the sum of the advice in these guidelines across all areas.
Thursday, May 22, 2008
Overview of the Click Thinking Pack
At the same time, the media tends to focus on the rare occasions when use of the Internet causes distress. The Scottish Executive believes that young people need to be protected and informed; and that those responsible for them, whether teachers, parents or other careers, should be aware of the issues involved.
Previous Scottish Executive Education Department (SEED) publications in this area have dealt with the need to protect pupils from misuse of computers (Information Ethics) and to understand copyright implications (Copyright and Ethics in a Digital Age).
This booklet focuses on personal safety and wellbeing. It attempts to clarify potential risks and to empower Internet users in schools so that they can keep themselves safe. Those who manage Scottish schools, and all teachers, whether responsible for a primary class or for teaching a subject, will find policy guidelines and background information which will prepare our pupils to take their safe and well-earned place in the Digital Age.
Much of the advice in these guidelines will be relevant to other Local Authority staff responsible for overseeing young people's use of the Internet (e.g. managers and staff in community education centers, residential homes for young people, libraries and other settings). These groups should take account of the messages about personal safety, and put into place the recommendations suitable for their setting.
Wednesday, May 07, 2008
BACK TO SCHOOL SAFETY ALERT:
CPSC Document #5002
Each year about 800 bicyclists are killed and more than half a million are treated in hospital emergency rooms. In recent years, almost two-thirds of the deaths and one-third of the injuries involved head and face injury. About one-half the injuries to children under the age of 10 involved the head or face. Helmets may reduce the risk of head injury to bicyclists by as much as 85 percent. Yet, only about 50 percent of bicyclists wear helmets.
The purpose of a helmet is to absorb the energy of an impact to minimize or prevent a head injury. Crushable, expanded polystyrene foam generally is used for this purpose.
A bicycle helmet should have a snug but comfortable fit on the rider's head. Some helmets are available with several different thicknesses of internal padding to custom fit the helmet to the user. If a parent is buying a helmet for a child, the CPSC recommends that the child accompany the parent so that the helmet can be tested for a good fit.
For a helmet to provide protection during impact, it must have a chin strap and buckle that will stay securely fastened. No combination of twisting or pulling should remove the helmet from the head or loosen the buckle on the strap. Children should be instructed to always wear the helmet level on the forehead, not tilted back. The chin strap should be adjusted correctly and firmly buckled.
Helmets manufactured after March 1999, are required by federal law to meet the CPSC standard. When purchasing a helmet, consumers are urged to examine the helmet and accompanying instructions and safety literature carefully. Consumers should also look for a label stating conformance with the CPSC standard.
Bicyclists should avoid riding at night. If you must ride at night, install and use front and rear lights on the bicycle and wear clothing with reflective tape or markings. These precautions are in addition to the reflectors that the CPSC requires to be on the front, rear, pedals, and wheels of bicycles.
Many bicycle-car crashes can be avoided by applying the rules of the road and by increasing attentiveness of cyclists and motorists. Bicyclists have a legal right to share the road, but they are often not noticed in traffic. Drivers should always keep an eye out for bicyclists, especially when turning, merging, changing lanes, or entering intersections.
Monday, April 28, 2008
All-Terrain Vehicle Safety
An estimated 740 people died in 2003* in incidents associated with ATVs. In addition, in 2004* there were an estimated 136,100 emergency room treated injuries associated with ATVs. About a third of all deaths and injuries involved victims under 16 years old. CPSC also reported that ridership has continued to grow, with 6.2 million 4-wheeled ATVs in use in 2003*.
The major ATV manufacturers agreed in Consent Decrees in 1988 and in subsequent voluntary action plans that they would not manufacture three-wheel ATVs; they would place engine size restrictions on ATVs sold for use by children under 16; and they would offer driver-training programs.
Children and young people under the age of 16 should not ride adult ATVs.
All ATV users should take a hands-on safety training course.
Always wear a helmet and safety gear such as boots and gloves while on an ATV.
Never drive an ATV on paved roads.
Never drive while under the influence of drugs or alcohol.
Never drive a youth or single-rider adult ATV with a passenger, and never ride these vehicles as a passenger.
There are some ATVs that are designed for two riders. Passengers on tandem ATVs should be at least 12 years old.
Monday, April 21, 2008
J-Hook Shaped Stake style (Anchor Types)
Monday, April 14, 2008
Anchoring/Securing/Counterweighing Guidelines
Sunday, March 30, 2008
B.C.-Canada Place officially closes doors
Over the course of the 2006 Olympic and Paralympic Winter Games, British Columbia-Canada Place drew more than 100,000 visitors and journalists. These visitors were able to experience first hand the province’s culture, heritage, natural beauty and bustling cities. Also, more than 80 British Columbia businesses were able to connect with an international audience and showcase some of B.C.’s best products and services.
B.C.-Canada Place will be a legacy to the people of Torino. The official transfer took place in a ceremony yesterday, with Torino Mayor Sergio Chiamparino accepting a ceremonial key to the building.
“This generous gift from British Columbia will be a constant reminder of our friends in Canada and the celebrations that took place in our city during the 2006 Winter Games,” says Mayor Chiamparino. “We are honored to have this permanent B.C. presence in our city.”
Monday, March 24, 2008
Kent Kickin' Mini-Scooters
Kent has received four reports of the handles coming out, resulting in four children suffering injuries, including broken arms, a broken wrist, bruises, abrasions and a cracked tooth.
These are Kickin' Mini-Scooters made of chrome-plated steel. A vertical decal on the steering column reads "KICKIN' MINI SCOOTER." The scooter's black plastic platform measures about 15 inches long, and it has 4-inch translucent in-line style wheels. "KENT" and "MADE IN CHINA" are written on the lower part of the steering column. The scooters were sold with black backpacks embroidered in white with the word "Kickin."
Toys R us stores nationwide sold the Kent scooters from May 2000 through September 2000 for about $60.
Consumers should stop riding these Kent scooters immediately, and call Kent International to receive a free replacement handlebar with pins to secure the handlebars. For more information, call Kent International at (800) 451-KENT (5368) between 8 a.m. and 5 p.m. ET Monday through Friday.
Kent has sold other models to Toys R Us such as the Street Craze, the Street Racer and Scoot that are NOT part of this recall. Scooters that Kent sold to Wal Mart, Meijer's, Target and AAFES are also NOT part of this recall.
Monday, March 17, 2008
Trampoline Safety Alert
* Colliding with another person on the trampoline.
* Landing improperly while jumping or doing stunts on the trampoline.
* Falling or jumping off the trampoline.
* Falling on the trampoline springs or frame.
Most of the trampolines associated with injuries were at private homes.
Here are the steps you can take to help prevent serious trampoline injuries, especially paralysis, fractures, sprains, and bruises:
* Allow only one person on the trampoline at a time.
* Do not attempt or allow somersaults because landing on the head or neck can cause paralysis.
* Do not use the trampoline without shock-absorbing pads that completely cover its springs, hooks, and frame.
* Place the trampoline away from structures, trees, and other play areas.
* No child under 6 years of age should use a full-size trampoline. Do not use a ladder with the trampoline because it provides unsupervised access by small children.
* Always supervise children who use a trampoline.
* Trampoline enclosures can help prevent injuries from falls off trampolines.
Monday, March 10, 2008
Accumulator
In a computer CPU, an accumulator is a register in which intermediary arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation (addition, multiplication, shift, etc.) to main memory, possibly only to be read right back again for use in the next operation. Access to main memory is slower than access to a register like the accumulator because the technology used for the huge main memory is slower (but cheaper) than that used for a register.
The canonical example for accumulator use is adding a list of numbers. The accumulator is initially set to zero, then each number in spin is added to the value in the accumulator. Only when all numbers have been added is the result seized in the accumulator written to main memory or to another, non-accumulator, CPU register.
Monday, February 25, 2008
Semiconductor
Sunday, February 17, 2008
Professional engineer
As BME is an emerging field, professional certifications are not as standard and uniform as they are for other engineering fields. For example, the Fundamentals of Engineering exam in the U.S. does not include a biomedical engineering section, though it does cover biology. Biomedical engineers often simply possess a university degree as their qualification. However, some countries, such as Australia, do regulate biomedical engineers, however registration is typically only recommended and not required.
Wednesday, November 14, 2007
A general view on Mainframe computer
The word originated during the near the beginning 1970s with the introduction of smaller, less difficult computers for example the DEC PDP-8 and PDP-11 series, which became recognized as minicomputers or just minis. The industry/users then coined the word "mainframe" to describe bigger, earlier types (before known simply as "computers").
Mainframes often maintain thousands of simultaneous users who gain right of entry through "dumb" terminals or terminal emulation. Early mainframes either supported this timesharing mode or operated in batch mode where users had no straight access to the computing service, it exclusively providing back office functions. At this time mainframes were so called for the reason that of their very substantial size and requirements for specialized HVAC and electrical power. Nowadays mainframes support right of entry via any user interface, including the Web. Blade servers rather than mainframes are currently increasingly requiring "exotic" cooling technologies.
Sunday, November 04, 2007
Types of Boxes
Numerous types of boxes are used in eternal installations. Some types are designed to be for the time being inhabited by workers.
Permanent boxes include the following:
Equipment boxes - Fuse box
Compartments - Luxury box , Mailbox
Shelters or booths - Police box , Signal box , Telephone box
Permanent boxes
Numerous types of boxes are used in stable installations. Some types are designed to be provisionally inhabited by workers.
Sunday, October 28, 2007
The real facts about Uranus
Like the other gas planets, Uranus has bands of clouds that carry around rapidly. But they are very faint, visible only with radical image improvement of the Voyager 2 pictures (right). Recent observations with HST (left) show bigger and more pronounced streaks. Additional HST observations show even more activity. Uranus is no longer the ordinary boring planet that Voyager saw! It now seems understandable that the differences are due to seasonal effects since the Sun is now at lesser Uranian latitude which may because more pronounced day/night weather effects. By 2007 the Sun will be unswervingly over Uranus's equator.
Like the additional gas planets, Uranus has rings. Like Jupiter's, they are extremely dark but like Saturn's they are composed of quite large particles ranging up to 10 meters in diameter additionally to fine dust. There are 11 recognized rings, all very faint; the brightest is identified as the Epsilon ring. The Uranian rings were the first after Saturn's to be discovered. This was of great importance since we now know that rings are a common feature of planets, not a peculiarity of Saturn alone. Uranus' fascinating field is odd in that it is not centered on the center of the planet and is tilted almost 60 degrees with respect to the axis of rotary motion. It is almost certainly generated by motion at relatively shallow depths within Uranus.
Friday, October 26, 2007
The real facts about Neptune
Neptune's blue color is mainly the result of absorption of red light by methane in the atmosphere but there is a number of additional as-yet-unidentified chromophore which gives the clouds their rich blue tint. Like Jupiter and Saturn, Neptune has an inner heat source -- it radiates more than, twice as much energy as it receives from the Sun.
Neptune also has rings. Earth-based observations showed just faint arcs rather than complete rings, but Voyager 2's images showed them to be entire rings with bright clumps. One of the rings looks to have a curious twisted structure (right). Like Uranus and Jupiter, Neptune's rings are extremely dark but their composition is unknown.
Neptune's rings have been noted names: the outermost is Adams (which contains three important arcs now named Liberty, Equality and Fraternity), next is an unnamed ring co-orbital with Galatea, then Leverrier (whose outer extensions are called Lassell and Arago), and lastly the faint but broad Galle. Neptune's magnetic field is, like Uranus', oddly oriented and most likely generated by motions of conductive material (probably water) in its middle layers.
Tuesday, October 16, 2007
Cookie
Cookies can be baked until crisp or just long enough that they stay soft. Depending on the kind of cookie, some cookies are not cooked at all. Cookies are made in a broad variety of styles, using an array of ingredients including sugars, spices, chocolate, butter, peanut butter, nuts or dried fruits. The smoothness of the cookie may depend on how long it is baked.
Monday, October 08, 2007
Mainframes
The term originated during the early 1970s with the introduction of smaller, fewer complex computers such as the DEC PDP-8 and PDP-11 series, which became known as minicomputers or just minis. The industry/users then coined the term "mainframe" to describe bigger, earlier types (previously known simply as "computers").
Sunday, September 23, 2007
Traffic Light
Thursday, September 13, 2007
Goshawk
It is an extensive species all through the moderate parts of the northern hemisphere. In North America it is named as the Northern Goshawk. It is typically inhabitant, but birds from colder regions of north Asia and Canada journey south for the winter.
Goshawk in flight this species nests in trees, building a new nest each year. It hunts birds and mammals in woodland, relying on revelation as it flies from a perch or hedge-hops to catch its quarry ignorant. Animals as large as hares and Pheasant are taken. Its call is a ferocious screech. Many older goshawks reject to attack hares, if it was earlier seriously kicked by a hare which it tried to catch.
This bird is a raptor with short large wings and a long tail, both adaptations to maneuvering through trees. The male is blue-grey above and banned grey below, 49-56 cm long with a 93-105 cm wingspan. The much larger female is 58-64 cm long with a 108-127 cm wingspan, slate grey above grey below. The youthful is brown above and barred brown below. The flight is a characteristic "slow flap – slow flap – straight glide".
In Eurasia, the male is confusable with a female Sparrow hawk, but is superior, much bulkier and has moderately longer wings. In spring, he has an impressive roller-coaster display, and this is the best time to see this enigmatic forest bird.
Goshawk
It is an extensive species all through the moderate parts of the northern hemisphere. In North America it is named as the Northern Goshawk. It is typically inhabitant, but birds from colder regions of north Asia and Canada journey south for the winter.
Goshawk in flight this species nests in trees, building a new nest each year. It hunts birds and mammals in woodland, relying on revelation as it flies from a perch or hedge-hops to catch its quarry ignorant. Animals as large as hares and Pheasant are taken. Its call is a ferocious screech. Many older goshawks reject to attack hares, if it was earlier seriously kicked by a hare which it tried to catch.
This bird is a raptor with short large wings and a long tail, both adaptations to maneuvering through trees. The male is blue-grey above and banned grey below, 49-56 cm long with a 93-105 cm wingspan. The much larger female is 58-64 cm long with a 108-127 cm wingspan, slate grey above grey below. The youthful is brown above and barred brown below. The flight is a characteristic "slow flap – slow flap – straight glide".
In Eurasia, the male is confusable with a female Sparrow hawk, but is superior, much bulkier and has moderately longer wings. In spring, he has an impressive roller-coaster display, and this is the best time to see this enigmatic forest bird.
Wednesday, September 05, 2007
Tumor
Neoplastic tumors are caused by mutations in DNA of cells, which interfere with a cell's capability to regulate and limit cell division. An accumulation of mutations is needed for a tumor to emerge. Mutations that activate oncogenes or repress tumor suppressor genes can eventually lead to tumors. Cells have mechanisms that repair DNA and other mechanisms that cause the cell to destroy itself by apoptosis if DNA damage gets too severe. Mutations that repress the genes for these mechanisms can also ultimately guide to cancer. A mutation in one oncogene or one tumor repressor gene is usually not enough for a tumor to occur. A combination of a number of mutations is essential.
Tuesday, August 21, 2007
Microcomputer
Monday, August 13, 2007
Salad
Monday, July 30, 2007
Traffic Claming
Sunday, July 22, 2007
Lighthouse of Alexandria
With a height variously estimated at between 115 and 150 meters (383 - 450 ft) it was among the tallest man-made structures on Earth for many centuries, and was recognized as one of the Seven Wonders of the World by Antipater of Sidon. It was the third tallest building after the two Great Pyramids (of Khufu and Khafra) for its whole life. Some scientists approximate a much taller height exceeding 180 metres that would make the tower the tallest building up to the 14th century.
Sunday, July 15, 2007
Bay of Bengal
The
The
Monday, July 09, 2007
Marketing
Thursday, July 05, 2007
CPU Socket
Most CPU sockets and processors in use today are built around the pin grid array (PGA) architecture, in which the pins on the base of the processor are inserted into the socket. To aid installation, zero insertion force (ZIF) sockets are usually used, allowing the processor to be inserted without any confrontation, while gripping the pins firmly once the processor is in place to ensure a reliable contact. In contrast to CPU sockets, slot-based processors and CPUs use a single-edged connection rather than a socket, and slot into the motherboard on their side. Slot architectures are not often used today
Sunday, July 01, 2007
Swan
Swans typically mate for life, though "divorce" does sometimes occur, mainly following nesting failure. The number of eggs in each clutch is between 3–8.
The word is derived from Old English swan, akin to German Schwan, in turn derived from Indo-European root *swen (to sound, to sing), whence Latin derives sonus (sound). Young swans are known as cygnets, from the Latin word for swan, cygnus. An adult male is a cob, from Middle English cobbe; an adult female is a pen .
Wednesday, June 27, 2007
RISC (reduced instruction set computer)
The first commercial design was released by MIPS Technologies, the 32-bit R2000. The R3000 made the design truly practical, and the R4000 introduced the world's first 64-bit design. Opposing projects would result in the IBM POWER and Sun SPARC systems, respectively. Soon every major vendor was releasing a RISC design, including the AT&T CRISP, AMD 29000, Intel i860 and Intel i960, Motorola 88000, DEC Alpha and the HP-PA.
Market forces have "weeded out" many of these designs, leaving the PowerPC as the main desktop RISC processor, with the SPARC being used in Sun designs only. MIPS continue to supply some SGI systems, but are first and foremost used as an embedded design, notably in Cisco routers. The rest of the original crop of designs have either disappeared, or are about to. Other companies have attacked niches in the market, notably ARM, originally intended for home computer use but since focused at the embedded processor market. Today RISC designs based on the MIPS, ARM or PowerPC core are the vast majority of computing devices.
Sunday, June 24, 2007
Neem cake
Tuesday, June 19, 2007
Tide
The changing tide produced at a given location is the result of the changing positions of the Moon and Sun relative to the Earth coupled with the effects of Earth rotation and the local bathymetry.Sea level measured by coastal tide gauges may also be strongly affected by wind. More generally, tidal phenomena can occur in other systems besides the ocean, whenever a gravitational field that varies in time and space is present
Friday, June 15, 2007
Canoe
Canoe
Monday, June 11, 2007
Krill fishery
Krill are rich in protein (40% or more of dry weight) and lipids . Their exoskeleton amounts to some 2% of dry weight of chitin. They also contain traces of a wide array of hydrolytic enzymes such as proteases, carbohydrases, nucleases and phospholipases, which are intense in the digestive gland in the cephalothorax of the krill.
Most krill is used as aquaculture feed and fish bait; other uses comprise livestock or pet foods. Only a small percentage is prepared for human consumption. Their enzymes are interesting for medical applications, an expanding sector since the early 1990s.
Thursday, June 07, 2007
Deadheading
Deadheading is beneficial to most herbaceous ornamental plants. It can get better overall look of a plant, give a fresh new look to an otherwise finished or even distracting item, and can promote vegetative and root increase rather than seed production and help retain the plant's healthy appearance.
Friday, June 01, 2007
Fire
Monday, May 28, 2007
JAR
* WAR (file format) (Web Application aRchive) files are also Java archives which store XML files, java classes, Java Server Pages and other objects for Web Applications.
* EAR (file format) (Enterprise ARchive) files are also Java archives which store XML files, java classes and other objects for Enterprise Applications.
* RAR (file format) (Resource Adapter aRchive) files are also Java archives which store XML files, java classes and other objects for J2EE Connector Architecture (JCA) applications.
JAR files can be created and extracted using the "jar" command that comes with the JDK. It can be done using zip tools, but as WinZip has a habit of renaming all-uppercase directories and files in lower case, this can raise support calls with whoever shaped the JAR or the tool authors themselves. WinRAR, on the other hand, retains the original case of filenames.
A JAR file has a manifest file located in the path META-INF/MANIFEST.MF. The entries in the manifest file determine how the JAR file will be used. JAR files which are intended to be executed as standalone programs will have one of their classes specified as the "main" class. The manifest file would have an entry such as
Main-Class: myPrograms.MyClass
Such JAR files are typically started with a command similar to
java -jar foo.jar
These files can also include a Classpath entry, which identifies other JAR files to be loaded with the JAR. This entry consists of a list of absolute or relative paths to other JAR files. Although intended to simplify JAR use, in practice, it turns out to be notoriously brittle as it depends on all the relevant JARs being in the exact locations specified when the entry-point JAR was built. To change versions or locations of libraries, a new manifest is needed.
Thursday, May 24, 2007
Nutrition
Between extremes of optimal health and death from starvation or malnutrition, there is an array of disease states that can be caused or alleviated by changes in diet. Deficiencies, excesses and imbalances in diet can produce negative impacts on health, which may lead to diseases such as scurvy, obesity or osteoporosis, as well as mental and behavioral problems. Moreover, excessive ingestion of elements that have no apparent role in health, (e.g. lead, mercury, PCBs, dioxins), may incur toxic and potentially lethal belongings, depending on the dose. The science of nutrition attempts to understand how and why exact dietary aspects influence health.
Sunday, May 20, 2007
Organization in sociology
An organization is defined by the rudiments that are part of it, its communication, its independence and its rules of action compared to outside events. By coordinated and planned cooperation of the elements, the organization is able to solve tasks that lie beyond the abilities of the single elements. The price paid by the elements is the restriction of the degrees of freedom of the elements. Advantages of organizations are enhancement, addition, and extension. Disadvantages are inertness and loss of interaction.
Tuesday, May 15, 2007
Stamp Collecting
Collecting is not the similar as philately, which is the study of stamps. A philatelist often does, but need not, collect the objects of study, nor is it required to closely study what one collects. Many informal collectors enjoy accumulating stamps without worrying about the tiny details, but the creation of a large or wide-ranging collection generally requires some philatelic knowledge.
History
The primary postage stamp, the One Penny Black, was issued by Britain in 1840. It pictured a young Queen Victoria, was formed without perforations, and accordingly had to be cut from the sheet with scissors in order to be used. While unused examples of the "Penny Black" are quite scarce, used examples are common, and may be purchased for $25 to $150, depending upon state.
Queen Victoria's outline was a staple on 19th century stamps of the British Empire; here on a half-penny of the Falkland Islands, 1891.During the late 1800s many of those collectors, now adults, began to systematically study the available postage stamps and published research works on their manufacture, plate flaws, etc.
Friday, May 11, 2007
Paint
Paint is used to protect, decorate (such as adding color), or add functionality to an object or outside by covering it with a pigmented coating. An example of protection is to retard corrosion of metal. An example of decoration is to add festive trim to a room interior. An example of added functionality is to alter light reflection or heat radiation of a surface.
As a verb, painting is the application of paint. Someone who paints creatively is usually called a painter, while someone who paints commercially is often referred to as a painter and decorator, or house painter.
Paint can be applied to almost any kind of object. It is used, among many other uses, in the production of art, in industrial coating, as a driving aid, or as a barrier to prevent corrosion or water damage. Paint is a semifinished product, as the final product is the painted article itself.
Monday, May 07, 2007
Belt (clothing)
Wednesday, May 02, 2007
Speed limit
Design speed
Speed limits are only peripherally interrelated to the design speed of the road.
In the United States, the design speed is "a selected speed used to establish the various geometric design features of the roadway" according to the 2001 AASHTO Green Book, the highway design manual. It has been changed from previous versions which considered it the "highest safe speed that can be maintained over a specific section of highway when conditions are so positive that the design facial appearance of the highway governs."
The design speed has largely been discredited as a sole basis for establishing a speed limit. Current U.S. standards for design speed derive from outdated, less-capable automotive technology. Also, the design speed of a given roadway is the theoretical maximum safe speed of the roadway's worst feature .The design speed usually underestimates the highest safe speed for a roadway and is therefore considered only a very conservative "first guess" at a limit.
85th percentile rule
An automobile dashboard viewing the speedometer with primary markings in miles per hour.Since the 1950s, United States traffic engineers have been taught the 85th Percentile Rule. The idea is that the speed limit should be set to the speed below which 85% of vehicles are traveling. The 85th percentile closely corresponds to one normal deviation above the mean of a normal distribution.
Every state in the United States statutorily or administratively picks a particular speed for a speed limit cap, meaning that no speed limit in that state may be set higher than the cap. A practical effect of this cap is that nearly every rural roadway in the U.S. has a speed limit that is well below the 85th percentile speed.
Sunday, April 29, 2007
Lighting rod
A lightning conductor,
A lightning arrester, or
A lightning discharger.
However, these terms really refer to lightning guard systems in general or specific mechanism within them.
Lightning rod dissipaters make a structure less nice-looking by which charges can flow to the air around it. This then reduces the voltage between the point and the storm cloud, making a strike less likely. The most common charge dissipaters appear as slightly-blunted metal spikes sticking out in all information from a metal ball. These are mounted on short metal arms at the very top of a radio antenna or tower, the area by far most likely to be struck. These devices diminish, but do not eradicate, the risk of lightning strikes.
Monday, April 23, 2007
American Robin
The American Robin is 25-28 cm (10-11 in) long. It has gray upperparts and head, and orange underparts, typically brighter in the male; the similarity between this coloring and that of the smaller and unrelated European Robin led to its common name. There are seven races, but only T . m. confinus in the southwest is mainly distinctive, with pale gray-brown underparts
During the breeding season, the adult males grow distinctive black feathers on their heads; after the breeding season they lose this eye-catching plumage.
This bird breeds all through Canada and the United States. While Robins infrequently overwinter in the northern part of the United States and southern Canada, most winter in the southern parts of the breeding range and beyond, from the southern USA to Guatemala. Most depart south by the end of August and begin to return north in March. This species is a very rare vagrant to western Europe. In autumn 2003, migration was displaced eastwards leading to massive movements through the eastern USA. most probably this is what led to no less than three American Robins being found in Great Britain, with two attempting to overwinter in 2003-4, one eventually being taken by a Sparrowhawk
Wednesday, April 18, 2007
Auto racing
Monday, April 09, 2007
"Wireless" factories and vacuum tubes
The next great invention was the vacuum tube detector, invented by a team of Westinghouse engineers. On Christmas Eve, 1906, Reginald Fessenden ransmitted the first radio audio broadcast in history from Brant Rock, Massachusetts. Ships at sea heard a broadcast that included Fessenden playing O Holy Night on the violin and reading a passage from the Bible. The world's first radio news program was broadcast August 31, 1920 by station 8MK in Detroit, Michigan. The world's first regular wireless broadcasts for entertainment commenced in 1922 from the Marconi Research Centre at Writtle near Chelmsford, England.
Thursday, April 05, 2007
Space missions
The first such mission was the Sputnik I mission, launched October 4, 1957. Some missions are more appropriate for unmanned missions rather than manned space missions, due to lower cost and lower risk factors.
Since the early 1970s, most unmanned space missions have been based on space probes with built-in mission computers, and as such may be classified as embedded systems.
Most American unmanned missions have been synchronized by the Jet Propulsion Laboratory, and European missions by the European Space Operations Centre, part of ESA (the European Space Agency).
ESA has conducted comparatively few space exploration missions. ESA has, however, launched a variety of spacecraft to carry out astronomy, and is a collaborator with NASA on the Hubble Space Telescope.
There has been a large number of very successful Russian space missions. There were also a few Japanese and Chinese missions.