Classification.

Back pain is classified in terms of duration of symptoms.

Causes.

There are many causes of back pain, including blood vessels, internal organs, infections, mechanical, and autoimmune causes. Approximately 90 percent of people with back pain are diagnosed with nonspecific acute back pain in which there is no serious underlying pathology. In approximately 10 percent of people, cause can be identified through diagnostic imaging. Less than 2 percent are attributed to secondary factors, with metastatic cancers and serious infections, such as spinal osteomyelitis and epidural abscesses, accounting for around 1 percent.

Nonspecific.

In as many as 90 percent of cases, no physiological causes or abnormalities on diagnostic tests can be found. Nonspecific back pain can be due to back strain/sprain. The cause is peripheral injury to muscle or ligaments. The patient may or may not recall the cause. The pain can present acutely but in some cases can persist, leading to chronic pain.  Chronic back pain in people with otherwise normal scans can result from central sensitization, where an initial injury causes a longer-lasting state of heightened sensitivity to pain. This persistent state maintains pain even after the initial injury has healed. Treatment of sensitization may involve low doses of anti-depressants and directed rehabilitation such as physical therapy.

Spinal disc disease.

Spinal disk disease occurs when the nucleus pulposus, a gel-like material in the inner core of the vertebral disc, ruptures. Rupturing of the nucleus pulposus can lead to compression of nerve roots. Symptoms may be unilateral or bilateral, and correlate to the region of the spine affected. The most common region for spinal disk disease is at L4-L5 or L5-S1. The risk for lumbar disc disease is increased in overweight individuals due to the increased compressive force on the nucleus pulposus.  Severe spinal cord compression is considered a surgical emergency and requires decompression to preserve motor and sensory function. Cauda equina syndrome refers to severe compression of the cauda equina and presents initially with pain followed by motor and sensory. Bladder incontinence is seen in later stages of the cauda equina syndrome.

Degenerative disease.

Spondylosis, or degenerative arthritis of the spine, occurs when the intervertebral disc undergoes degenerative changes, causing the disc to fail at cushioning the vertebrae. There is an association between intervertebral disc space narrowing and lumbar spine pain. The space between the vertebrae becomes more narrow, resulting in compression and irritation of the nerves.  Spondylolithesis is the anterior shift of one vertebra compared to the neighboring vertebra. It is associated with age-related degenerative changes as well as trauma and congenital anomalies.  Spinal stenosis can occur in cases of severe spondylosis, spondylotheisis and age associated thickening of the ligamentum flavum. Spinal stenosis involves narrowing of the spinal canal and typically presents in patients greater than 60 years of age. Neurogenic claudication can occur in cases of severe lumbar spinal stenosis and presents with symptoms of pain in the lower back, buttock or leg that is worsened by standing and relieved by sitting.  Vertebral compression fractures occurs in 4 percent of patients presenting to primary care with low back pain. Risk factors include age, female gender, history of osteoporosis, and chronic glucocorticoid use. Fractures can occur due to trauma but in many cases can be asymptomatic.

Infection.

Common infectious causes of back pain include osteomyelitis, septic diskitis, paraspinal abscess, and epidural abscess. Infectious causes that lead to back pain involve various structures surrounding the spine.  Osteomyelitis is the bacterial infection of the bone. Vertebral osteomyelitis is most commonly caused by staphylococci. Risk factors include skin infection, urinary tract infection, IV catheter use, IV drug use, previous endocarditis, and lung disease.  Spinal epidural abscess is also commonly caused by severe infection with bacteremia. Risk factors include recent epidural, IV drug use, or recent infection.

Cancer.

Spread of cancer to the bone or spinal cord can lead to back pain. Bone is one of the most common sites of metastatic lesions. Patients typically have a history of malignancy. Common types of cancer that present with back pain include multiple myeloma, lymphoma, leukemia, spinal cord tumors, primary vertebral tumors, and prostate cancer. Back pain is present in 29% of patients with systemic cancer. Unlike other causes of back pain which common affect the lumbar spine, the thoracic spine is most commonly affected. The pain can be associated with systemic symptoms such as weight loss, chills, fever, nausea and vomiting. Unlike other causes of back pain, neoplasm-associated back pain is constant, dull, poorly localized, and worst with rest. Metastasis to the bone also increases the risk of spinal cord compression or vertebral fractures which requires emergent surgical treatment.

Autoimmune.

Inflammatory arthritides such as ankylosing spondylitis, psoriatic arthritis, rheumatoid arthritis, and systemic lupus erythematosus can all cause varying levels of joint destruction. Among the inflammatory arthritides, ankylosing spondylitis is most closely associated with back pain due to the inflammatory destruction of the bony components of the spine. Ankylosing spondylitis is common in young men and presents with a range of possible symptoms such as uveitis, psoriasis, and inflammatory bowel disease.

Referred pain.

Back pain can also be due to referred pain from another source. Referred pain occurs when pain is felt at a location different from the source of the pain. Disease processes that can present with back pain include pancreatitis, kidney stones, severe urinary tract infections, and abdominal aortic aneurysms.

Risk factors.

Heavy lifting, obesity, sedentary lifestyle, and lack of exercise can increase a person's risk of back pain. People who smoke are more likely to experience back pain than others. Poor posture and weight gain in pregnancy are also risk factors for back pain. In general, fatigue can worsen pain.  A few studies suggest that psychosocial factors such as on-the-job stress and dysfunctional family relationships may correlate more closely with back pain than structural abnormalities revealed in X-rays and other medical imaging scans.

Diagnosis.

Initial assessment of back pain consists of a history and physical examination. Important characterizing features of the back pain include location, duration, severity, history of prior back pain, and possible trauma. Other important components of the patient history include age, physical trauma, prior history of cancer, fever, weight loss, urinary incontinence, progressive weakness, or expanding sensory changes, which can elicit red flags indicating a medical urgent condition.  Physical examination of the back should assess for posture and deformities. Pain elicited by palpating certain structures may be helpful in localizing the affected area. A neurologic exam is needed to assess for changes in gait, sensation, and motor function.  Determining if there are radicular symptoms, such as pain, numbness, or weakness that radiates down limbs, is important for differentiating between central and peripheral causes of back pain. The straight leg test is a maneuver used to determine the presence of lumbosacral radiculopathy. Radiculopathy occurs when there is irritation in the nerve root, causing neurologic symptoms, such as numbness and tingling. Non-radicular back pain is most commonly caused by injury to the spinal muscles or ligaments, degenerative spinal disease, or a herniated disk. Disk herniation and foraminal stenosis are the most common causes of radiculopathy.  Imaging of the spine and laboratory tests is not recommended during the acute phase. This assumes that there is no reason to expect that the person has an underlying problem. In most cases, the pain goes away naturally after a few weeks. Typically, people who do seek diagnosis through imaging are not likely to have a better outcome than those who wait for the condition to resolve.

Imaging.

Magnetic resonance imaging is the preferred modality for the evaluation of back pain and visualize bone, soft tissue, nerves, and ligaments. X-rays are a less costly initial option offered to patients with a low clinical suspicion of infection or malignancy and is combined with laboratory studies for interpretation.  Imaging is not needed in the majority of individuals with back pain. In cases of acute back pain, MRI is recommended for individuals with major risk factors/clinical suspicion for cancer, spinal infection, or severe progressive neurological deficits. For patients with subacute to chronic back pain, MRI is recommended if there are minor risk factors for cancer, risk factors for ankylosing spondylitis, risk factors for vertebral compression fracture, significant trauma, or symptomatic spinal stenosis.  Early imaging studies during the acute phase do not improve care or prognosis in patients. Imaging findings are not correlated with severity or outcome.

Laboratory studies.

Laboratory studies are used to if there are suspicions for autoimmune causes, infection, or malignancy. Laboratory testing may include white blood cell (WBC) count, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP).

Red flags.

Imaging is not typically needed in the initial diagnosis or treatment of back pain. However, if there are certain "red flag" symptoms present plain radiographs (x-ray), CT scan, or magnetic resonance imaging (MRI) may be recommended. These red flags include:

Prevention.

There is moderate quality evidence that suggests the combination of education and exercise may reduce an individual's risk of developing an episode of low back pain. Lesser quality evidence points to exercise alone as a possible deterrent to the risk of the onset of this condition.

Management.

Nonspecific pain.

Patients with uncomplicated back pain should be encouraged to remain active and return to normal activities.  The management goals when treating back pain are to achieve maximal reduction in pain intensity as rapidly as possible, to restore the individual's ability to function in everyday activities, to help the patient cope with residual pain, to assess for side-effects of therapy, and to facilitate the patient's passage through the legal and socioeconomic impediments to recovery. For many, the goal is to keep the pain to a manageable level to progress with rehabilitation, which then can lead to long-term pain relief. Also, for some people the goal is to use non-surgical therapies to manage the pain and avoid major surgery, while for others surgery may be the quickest way to feel better.  Not all treatments work for all conditions or for all individuals with the same condition, and many find that they need to try several treatment options to determine what works best for them. The present stage of the condition (acute or chronic) is also a determining factor in the choice of treatment. Only a minority of people with back pain (most estimates are 1% - 10%) require surgery.

Non medical.

Back pain is generally treated with non-pharmacological therapy first, as it typically resolves without the use of medication. Superficial heat and massage, acupuncture, and spinal manipulation therapy may be recommended.

Medication.

If non-pharmacological measures are not effective, medications may be tried.

Surgery.

Surgery for back pain is typically used as a last resort, when serious neurological deficit is evident. A 2009 systematic review of back surgery studies found that, for certain diagnoses, surgery is moderately better than other common treatments, but the benefits of surgery often decline in the long term.  Surgery may sometimes be appropriate for people with severe myelopathy or cauda equina syndrome. Causes of neurological deficits can include spinal disc herniation, spinal stenosis, degenerative disc disease, tumor, infection, and spinal hematomas, all of which can impinge on the nerve roots around the spinal cord. There are multiple surgical options to treat back pain, and these options vary depending on the cause of the pain.  When a herniated disc is compressing the nerve roots, hemi- or partial- laminectomy or discectomy may be performed, in which the material compressing on the nerve is removed. A mutli-level laminectomy can be done to widen the spinal canal in the case of spinal stenosis. A foraminotomy or foraminectomy may also be necessary, if the vertebrae are causing significant nerve root compression. A discectomy is performed when the intervertebral disc has herniated or torn. It involves removing the protruding disc, either a portion of it or all of it, that is placing pressure on the nerve root. Total disc replacement can also be performed, in which the source of the pain (the damaged disc) is removed and replaced, while maintaining spinal mobility. When an entire disc is removed (as in discectomy), or when the vertebrae are unstable, spinal fusion surgery may be performed. Spinal fusion is a procedure in which bone grafts and metal hardware is used to fix together two or more vertebrae, thus preventing the bones of the spinal column from compressing on the spinal cord or nerve roots.  If infection, such as a spinal epidural abscess, is the source of the back pain, surgery may be indicated when a trial of antibiotics is ineffective. Surgical evacuation of spinal hematoma can also be attempted, if the blood products fail to break down on their own.

Pregnancy.

About 50% of women experience low back pain during pregnancy. Some studies have suggested women who have experienced back pain before pregnancy are at a higher risk of having back pain during pregnancy. It may be severe enough to cause significant pain and disability in up to a third of pregnant women. Back pain typically begins at around 18 weeks gestation, and peaks between 24 and 36 weeks gestation. Approximately 16% of women who experienced back pain during pregnancy report continued back pain years after pregnancy, indicating those with significant back pain are at greater risk of back pain following pregnancy.  Biomechanical factors of pregnancy shown to be associated with back pain include increased curvature of the lower back, or lumbar lordosis, to support the added weight on the abdomen. Also, a hormone called relaxin is released during pregnancy that softens the structural tissues in the pelvis and lower back to prepare for vaginal delivery. This softening and increased flexibility of the ligaments and joints in the lower back can result in pain. Back pain in pregnancy is often accompanied by radicular symptoms, suggested to be caused by the fetus pressing on the sacral plexus and lumbar plexus in the pelvis.  Typical factors aggravating the back pain of pregnancy include standing, sitting, forward bending, lifting, and walking. Back pain in pregnancy may also be characterized by pain radiating into the thigh and buttocks, night-time pain severe enough to wake the patient, pain that is increased during the night-time, or pain that is increased during the day-time.  Local heat, acetaminophen (paracetamol), and massage can be used to help relieve the pain. Avoiding standing for prolonged periods of time is also suggested.

Economics.

Although back pain does not typically cause permanent disability, it is a significant contributor to physician visits and missed work days in the United States, and is the single leading cause of disability worldwide. The American Academy of Orthopaedic Surgeons report approximately 12 million visits to doctor's offices each year are due to back pain. Missed work and disability related to low back pain costs over $50 billion each year in the United States. In the United Kingdom in 1998, approximately £1.6 billion per year was spent on expenses related to disability from back pain.

Back pain, also known as backache, is pain felt in the back. The back is divided into neck pain (cervical), middle back pain (thoracic), lower back pain (lumbar) or coccydynia (tailbone or sacral pain) based on the segment affected. The lumbar area is the most common area affected. Episodes of back pain may be acute, sub-acute, or chronic depending on the duration. The pain may be characterized as a dull ache, shooting or piercing pain, or a burning sensation. Discomfort can radiate into the arms and hands as well as the legs or feet, and may include numbness, or weakness in the legs and arms. The majority of back pain is nonspecific with no identifiable causes. Common underlying mechanisms include degenerative or traumatic changes to the discs and facets joints, which can then cause secondary pain in the muscles, and nerves, and referred pain to the bones, joints and extremities. Diseases and inflammation of the gallbladder, pancreas, aorta, and kidneys may also cause referred pain in the back. Tumors of the vertebrae, neural tissues and adjacent structures can also manifest as back pain. Back pain is common, with about nine out of ten adults experiencing it at some point in their life, and five out of ten working adults having it every year. Some estimate up to 95% of people will experience back pain at some point in their lifetime. It is the most common cause of chronic pain, and is a major contributor of missed work and disability. For most individuals, back pain is self-limiting. In most cases of herniated disks and stenosis, rest, injections or surgery have similar general pain resolution outcomes on average after one year. In the United States, acute low back pain is the fifth most common reason for physician visits and causes 40% of missed days off work. Additionally, it is the single leading cause of disability worldwide.

背痛包括有肌肉、神经、骨骼、关节或与脊柱相关的其它方面的疼痛。背痛可以分为颈部疼痛、肩部疼痛、腰部疼痛和尾椎疼痛,又可分为急性或慢性、持续或间歇性、同一部位或多个部位的疼痛。麻木、刺痛或者是灼烧感都是常见的症状。背痛也可能会扩散到手臂、双手、肩部、或者腰部,甚至是下肢或者脚部。背痛是患者问诊最常见的原因之一。在美国,急性腰痛是第五大问诊的疾病,平均每10个成年人中有9人一生都至少会有一次背痛的经历,而每10个工人中有一半每年都会患有背痛。 脊柱是人体中结构复杂的中轴骨,连接丰富的神经、关节、肌肉、筋腱和韧带,而这些组织都会引起或触发疼痛。脊柱内的中枢神经连通到手臂和腿部,因此疼痛会转移到四肢。


Classification.

Turkmen is a member of the East Oghuz branch of the Turkic family of languages; its closest relatives being Turkish and Azerbaijani, with which it shares a relatively high degree of mutual intelligibility.  Turkmen has vowel harmony, is agglutinative and has no grammatical gender. Word order is subject–object–verb.  Written Turkmen today is based on the Teke (Tekke) dialect. The other dialects are Nohurly, Ýomud, Änewli, Hasarly, Nerezim, Gökleň, Salyr, Saryk, Ärsary and Çowdur. The Russian dialect is Trukhmen. The Teke dialect is sometimes (especially in Afghanistan) referred to as "Chagatai", but like all Turkmen dialects it reflects only a limited influence from classical Chagatai.

Writing system.

Officially, Turkmen is rendered in the "Täze Elipbiý" or "New Alphabet", which is based on the Latin alphabet. Many political parties in opposition to the authoritarian rule of President Saparmurat Niyazov continued to use the Cyrillic alphabet on websites and publications, most likely to distance themselves from the alphabet that Niyazov created.  Turkmen was written in an Arabic alphabet until 1 September 1928 when a Latin script was introduced. In 1940, Turkmen, like othere Soviet Republics, adopted Cyrillic. As a result of the fall of the Soviet Union, the Turkmen government abolished Cyrillic and intruduced Latin script in 1993.

Phonology.

The following phonemes are present in the Turkmen language:

Vowels.

Turkmen contains both short and long vowels. Doubling the duration of sound for a short vowel is generally how its long vowel counterpart is pronounced. Turkmen employs vowel harmony, a principle that is common in fellow Turkic languages. Vowels and their sounds are as follows:

Consonants.

Turkmen consonant phonemes (shown with the letters of the Turkmen alphabet used to represent them): Note that s/с and z/з represent and, which are not and, a unique feature among the Turkic languages (cf. "ceceo" in some Spanish dialects).

Vowel harmony.

Like other Turkic languages, Turkmen is characterized by vowel harmony. In general, words of native origin consist either entirely of front vowels (inçe çekimli sesler) or entirely of back vowels (ýogyn çekimli sesler). Prefixes and suffixes reflect this harmony, taking different forms depending on the word to which they are attached.  The infinitive form of a verb determines whether it will follow a front vowel harmony or back vowel harmony. Words of foreign origin, mainly Russian, Persian, or Arabic, do not follow vowel harmony.

Grammar.

Verbs.

Verbs are conjugated for singular and plural number and first, second, and third persons. There are 11 verb tenses: present comprehensive (long and short form), present perfect (regular and negative), future certain, future indefinite, conditional, past definite, obligatory, imperative, and intentional.  There are two types of verbs in Turkmen, distinguished by their infinitive forms: those ending in the suffix "-mak" and those ending in "-mek". -Mak verbs follow back vowel harmony, whereas -mek verbs follow front vowel harmony.

Evidentiality.

Evidentiality of a reported event is determined by four markers, affixed to the finite verb, roughly:  Here "Y" represents the close vowel conforming to vowel harmony. Some independent particles may be said to convey evidentiality: one such word is the particle "eken".

Negation.

One way to express negation in Turkmen is with the predicative adjective ýok, which indicates absence.  The phonetically similar suffix -ok is another option: it attaches to the verb which it negates. It comes after the stem and before the tense suffix. -Ok does not modify its form due to vowel harmony. In addition to -ok there is another suffix -me or -ma. It appears -mV is used when dealing with one event, -ok for more habitual or lasting states:  Speakers of Eastern dialects of Turkmen, influenced by Uzbek, are less likely to utilize the -ok suffix.  Yet another way of expressing negation is by the negative particle däl.  There is not an equivalent in Turkmen to the English prefix 'un-'. That is, one can't simply attach an affix to a verb to indicate the opposite action, as in wrap the present → unwrap the present.  It appears that different tenses use different forms of negation, as in the following sentences:

Turkmen case system.

Turkmen has six cases: Accusative, Dative, Genitive, Instrumental, Locative, and Nominative. Back Vowels: The noun sygyr "cow" declined in the six Turkmen cases, with Jenneta's examples of how it would be used for each:  Front Vowels: The proper noun Jeren (a woman's name) declined in the six Turkmen cases, with examples of how it would be used for each:

Suffixes.

Suffixes, or "goşulmalar", form a very important part of Turkmen. They can mark possession, or change a verb.  Suffixes reflect vowel harmony.

Literature.

The leading Turkmen poet is Magtymguly Pyragy, who wrote in the eighteenth century. His language represents a transitional stage between Chagatai and spoken Turkmen.

Vocabulary.

Numbers.

Note: Numbers are formed identically to other Turkic languages, such as Turkish. So, eleven (11) is "on bir" (ten-one). Two thousand seventeen (2017) is "iki müň on ýedi" (two-thousand-ten-seven).

"Türkmeniň".

Magtymguly's most famous poem among the 1.3 million Iranian Turkmen is "Türkmeniň" ("Of the Turkmen"). The poem concerns the geography of the Turkmen people, and it sings praise for their culture. The poem became a rallying cry for Turkmen independence during the Iranian Revolution. The poem can be read aloud or sung in groups. The Iranian Turkmen dialect is closer to Turkish, so they refer to the poet as "Mahtumkulu Firaki".

Turkmen (,,, or,,, ) is an Oghuz Turkic language spoken by the Turkmens of Central Asia and the official language of Turkmenistan. It has an estimated five million native speakers in Turkmenistan, a further 719,000 speakers in Northeastern Iran and 1.5 million people in Northwestern Afghanistan.

土库曼语(),是土库曼斯坦的官方语言,属于阿尔泰语系突厥语族乌古斯语支南支。土库曼语在土库曼斯坦约有 340 万人使用,另外在伊朗有200万使用者,阿富汗有约50万使用者。


Definition.

A steradian can be defined as the solid angle subtended at the center of a unit sphere by a unit area on its surface. For a general sphere of radius "r", any portion of its surface with area subtends one steradian at its center.  The solid angle is related to the area it cuts out of a sphere:  Because the surface area "A" of a sphere is 4"r", the definition implies that a sphere subtends 4 steradians (≈ 12.56637 sr) at its center. By the same argument, the maximum solid angle that can be subtended at any point is 4 sr.

Other properties.

If, it corresponds to the area of a spherical cap () (where "h" stands for the "height" of the cap) and the relationship holds. Therefore, in this case, one steradian corresponds to the plane (i.e. radian) angle of the cross-section of a simple cone subtending the plane angle 2"θ", with "θ" given by:  This angle corresponds to the plane aperture angle of 2"θ" ≈ 1.144 rad or 65.54°.  A steradian is also equal to the spherical area of a polygon having an angle excess of 1 radian, to of a complete sphere, or to ≈ 3282.80635 square degrees.  The solid angle of a cone whose cross-section subtends the angle 2"θ" is:

SI multiples.

Millisteradians (msr) and microsteradians (μsr) are occasionally used to describe light and particle beams. Other multiples are rarely used.

The steradian (symbol: sr) or square radian is the SI unit of solid angle. It is used in three-dimensional geometry, and is analogous to the radian, which quantifies planar angles. Whereas an angle in radians, projected onto a circle, gives a "length" on the circumference, a solid angle in steradians, projected onto a sphere, gives an "area" on the surface. The name is derived from the Greek'solid' + radian.

球面度(steradian,符号:sr)是立体角的国际单位。它可算是三维的弧度。其英文字是希腊语「立体」(stereos)和弧度(radian)的混合,另一常见的中文翻译为立弪。


Early life and work.

Ede Teller was born on January 15, 1908, in Budapest, Austria-Hungary, into a Jewish family. His parents were Ilona, a pianist, and Max Teller, an attorney. He was educated at the Fasori Lutheran Gymnasium, then in the Minta (Model) Gymnasium in Budapest. Jewish of origin, later in life Teller became an agnostic Jew. "Religion was not an issue in my family", he later wrote, "indeed, it was never discussed. My only religious training came because the Minta required that all students take classes in their respective religions. My family celebrated one holiday, the Day of Atonement, when we all fasted. Yet my father said prayers for his parents on Saturdays and on all the Jewish holidays. The idea of God that I absorbed was that it would be wonderful if He existed: We needed Him desperately but had not seen Him in many thousands of years." Like Albert Einstein and Richard Feynman, Teller was a late talker. He developed the ability to speak later than most children, but became very interested in numbers, and would calculate large numbers in his head for fun. Teller left Hungary for Germany in 1926, partly due to the discriminatory "numerus clausus" rule under Miklós Horthy's regime. The political climate and revolutions in Hungary during his youth instilled a lingering animosity for both Communism and Fascism in Teller.  From 1926 to 1928, Teller studied mathematics and chemistry at the University of Karlsruhe, where he graduated with a degree in chemical engineering. He has stated that the person who was responsible for him becoming a physicist is Herman Mark, who was a visiting professor, after hearing lectures on molecular spectroscopy where Mark made it clear to him that it was new ideas in physics that were radically changing the frontier of chemistry. Mark was an expert in polymer chemistry, a field which is essential to understanding biochemistry, and Mark taught him about the leading breakthroughs in quantum physics made by Louis de Broglie, among others. It was this exposure which he had gotten from Mark's lectures which is what motivated Teller to switch to physics. After informing his father of his intent to switch, his father was so concerned that he traveled to visit him and speak with his professors at the school. While a degree in chemical engineering was a sure path to a well-paying job at chemical

Manhattan Project.

Los Alamos Laboratory.

In 1942, Teller was invited to be part of Robert Oppenheimer's summer planning seminar, at the University of California, Berkeley for the origins of the Manhattan Project, the Allied effort to develop the first nuclear weapons. A few weeks earlier, Teller had been meeting with his friend and colleague Enrico Fermi about the prospects of atomic warfare, and Fermi had nonchalantly suggested that perhaps a weapon based on nuclear fission could be used to set off an even larger nuclear fusion reaction. Even though he initially explained to Fermi why he thought the idea would not work, Teller was fascinated by the possibility and was quickly bored with the idea of

Decision to drop the bombs.

In the days before and after the first demonstration of a nuclear weapon, the Trinity test in July 1945, his fellow Hungarian Leo Szilard circulated the Szilard petition, which argued that a demonstration to the Japanese of the new weapon should occur prior to actual use on Japan, and with that hopefully the weapons would never be used on people. In response to Szilard's petition, Teller consulted his friend Robert Oppenheimer. Teller believed that Oppenheimer was a natural leader and could help him with such a formidable political problem. Oppenheimer reassured Teller that the nation's fate should be left to the sensible politicians in Washington. Bolstered by Oppenheimer's influence, he decided to not sign the petition.  Teller therefore penned a letter in response to Szilard that read:  On reflection on this letter years later when he was writing his memoirs, Teller wrote:  Unknown to Teller at

Hydrogen bomb.

Despite an offer from Norris Bradbury, who had replaced Oppenheimer as the director of Los Alamos in November 1945, to become the head of the Theoretical (T) Division, Teller left Los Alamos on February 1, 1946, to return to the University of Chicago as a professor and close associate of Fermi and Goeppert-Mayer. Mayer's work on the internal structure of the elements would earn her the Nobel Prize in Physics in 1963. On April 18–20, 1946, Teller participated in a conference at Los Alamos to review the wartime work on the Super. The properties of thermonuclear fuels such as deuterium and the possible design of a hydrogen bomb were discussed. It was concluded that Teller's assessment of a hydrogen bomb had been too favourable, and that both the quantity of deuterium needed, as well as the radiation losses during deuterium burning, would shed doubt on its workability. Addition of expensive tritium to the thermonuclear mixture would likely lower its ignition temperature, but even so, nobody knew at that time how much tritium would be needed, and whether even tritium addition would encourage heat propagation.  At the end of the conference, in spite of opposition by some members such as Robert Serber, Teller submitted an optimistic report in which he said that a hydrogen bomb was feasible, and that further work should be encouraged on its development. Fuchs also participated in this conference, and transmitted this information to Moscow. With John von Neumann, he contributed an idea of using implosion to ignite the Super. The model of Teller's "classical Super" was so uncertain that Oppenheimer would later say that he wished the Russians were building their own hydrogen bomb based on that design, so that it would almost certainly retard their progress on it.  By 1949, Soviet-backed governments had already begun seizing control throughout Eastern Europe, forming such puppet states as the Hungarian People's Republic in Teller's homeland of Hungary, where much of his family still lived, on August 20, 1949. Following the Soviet Union's first test detonation of an atomic bomb on August 29, 1949, President Harry Truman announced a crash development program for a hydrogen bomb.  Teller returned to Los Alamos in 1950 to work on the project. He insisted on involving more theorists. but many of Teller's prominent colleagues, like Fermi and Oppenheimer, were sure that the project of the H-bomb was technically infeasible and politically undesirable. None of the available designs were yet workable. However Soviet scientists who had worked on their own hydrogen bomb have claimed that they developed it independently.  In 1950, calculations by the Polish mathematician Stanislaw Ulam and his collaborator Cornelius Everett, along with confirmations by Fermi, had shown that not only was Teller's earlier estimate of the quantity of tritium needed for the H-bomb a low one, but that even with higher amounts of tritium, the energy loss in the fusion process would be too great to enable the fusion reaction to propagate. However, in 1951 Teller and Ulam made a breakthrough, and invented a new design, proposed in a classified March 1951 paper, "On Heterocatalytic Detonations I: Hydrodynamic Lenses and Radiation Mirrors", for a practical megaton-range H-bomb. The exact contribution provided respectively from Ulam and Teller to what became known as the Teller–Ulam design is not definitively known in the public domain, and the exact contributions of each and how the final idea was arrived upon has been a point of dispute in both public and

Oppenheimer controversy.

Teller became controversial in 1954 when he testified against Oppenheimer at Oppenheimer's security clearance hearing. Teller had clashed with Oppenheimer many times at Los Alamos over issues relating both to fission and fusion research, and during Oppenheimer's trial he was the only member of the scientific community to state that Oppenheimer should not be granted security clearance. Asked at the hearing by Atomic Energy Commission (AEC) attorney Roger Robb whether he was planning "to suggest that Dr. Oppenheimer is disloyal to the United States", Teller replied that:I do not want to suggest anything of the kind. I know Oppenheimer as an intellectually most alert and a very complicated person, and I think it would be presumptuous and wrong on my part if I would try in any way to analyze his motives. But I have always assumed, and I now assume that he is loyal to the United States. I believe this, and I shall believe it until I see very conclusive proof to the opposite.He was immediately asked whether he believed that Oppenheimer was a "security risk", to which he testified: Teller also testified that Oppenheimer's opinion about the thermonuclear program seemed to be based more on the scientific feasibility of the weapon than anything else. He additionally testified that Oppenheimer's direction of Los Alamos was "a very outstanding achievement" both as a scientist and an administrator, lauding his "very quick mind" and that he made "just a most wonderful and excellent director."  After this, however, he detailed ways in which he felt that Oppenheimer had

US government work and political advocacy.

After the Oppenheimer controversy, Teller became ostracized by much of the scientific community, but was still quite welcome in the government and military science circles. Along with his traditional advocacy for nuclear energy development, a strong nuclear arsenal, and a vigorous nuclear testing program, he had helped to develop nuclear reactor safety standards as the chair of the Reactor Safeguard Committee of the AEC in the late 1940s, and in the late 1950s headed an effort at General Atomics which designed research reactors in which a nuclear meltdown would be impossible. The TRIGA ("Training, Research, Isotopes, General Atomic") has been built and used in hundreds of hospitals and universities worldwide for medical isotope production and research.  Teller promoted increased defense spending to counter the perceived Soviet missile threat. He was a signatory to the 1958 report by the military sub-panel of the Rockefeller Brothers funded Special Studies Project, which called for a $3 billion annual increase in America's military budget.  In 1956 he attended the Project Nobska anti-submarine warfare conference, where discussion ranged from oceanography to nuclear weapons. In the course of discussing a small nuclear warhead for the Mark 45 torpedo, he

Global climate change.

Teller was one of the first prominent people to raise the danger of climate change, driven by the burning of fossil fuels. At an address to the membership of the American Chemical Society in December 1957, Teller warned that the large amount of carbon-based fuel that had been burnt since the mid-19th century was increasing the

Operation Plowshare and Project Chariot.

Teller was one of the strongest and best-known advocates for investigating non-military uses of nuclear explosives, which the United States explored under Operation Plowshare. One of the most controversial projects he proposed was a plan to use a multi-megaton hydrogen bomb to dig a deep-water harbor more than a mile long and half a mile wide to use for shipment of resources from coal and oil fields through Point Hope, Alaska. The Atomic Energy Commission accepted Teller's proposal in 1958 and it was designated Project Chariot. While the AEC was scouting out the Alaskan site, and having withdrawn the land from the public domain, Teller publicly advocated the economic benefits of the plan, but

Nuclear technology and Israel.

For some twenty years, Teller advised Israel on nuclear matters in general, and on the building of a hydrogen bomb in particular. In 1952, Teller and Oppenheimer had a long meeting with David Ben-Gurion in Tel Aviv, telling him that the best way to accumulate plutonium was to burn natural uranium in a nuclear reactor. Starting in 1964, a connection between Teller and Israel was made by the physicist Yuval Ne'eman, who had similar political views. Between 1964 and 1967, Teller visited Israel six times, lecturing at Tel Aviv University, and advising the chiefs of Israel's scientific-security circle as well as prime ministers and cabinet members.  In 1967 when the Israeli nuclear program was nearing completion, Teller informed Neeman that he was going to tell the CIA that Israel had

Three Mile Island.

Teller suffered a heart attack in 1979, and blamed it on Jane Fonda, who had starred in "The China Syndrome", which depicted a fictional reactor accident and was released less than two weeks before the Three Mile Island accident. She spoke out

Strategic Defense Initiative.

In the 1980s, Teller began a strong campaign for what was later called the Strategic Defense Initiative (SDI), derided by critics as "Star Wars," the concept of using ground and satellite-based lasers, particle beams and missiles to destroy incoming Soviet ICBMs. Teller lobbied with government agencies—and got the approval of President Ronald Reagan—for a plan to develop a system using elaborate satellites which used atomic weapons to fire X-ray lasers at incoming missiles—as part of a broader scientific research program into defenses against nuclear weapons.  Scandal erupted when Teller (and his associate Lowell Wood) were accused of deliberately overselling the program and perhaps encouraging the dismissal of

Asteroid impact avoidance.

Following the 1994 Shoemaker-Levy 9 comet impacts with Jupiter, Teller proposed to a collective of U.S. and Russian ex-Cold War weapons designers in a 1995 planetary defense workshop at Lawrence Livermore National Laboratory, that they collaborate to design a 1 gigaton nuclear explosive device, which would be equivalent to the kinetic energy of a 1 km diameter asteroid. In order to safeguard the earth, the theoretical 1 Gt device would weigh

Death and legacy.

Teller died in Stanford, California on September 9, 2003, at the age of 95. He had suffered a stroke two days before and had long been suffering from a number of conditions related to his advanced age.  A wish for his 100th birthday, made around the time of his 90th, was for Lawrence Livermore's scientists to give him "excellent predictions—calculations and experiments—about the interiors of the planets".  In his early career, Teller made contributions to nuclear and molecular physics, spectroscopy (the Jahn–Teller and Renner–Teller effects), and surface physics. His extension of Fermi's theory of beta decay (in the form of the so-called Gamow–Teller transitions) provided an important stepping stone in the applications of this theory. The Jahn–Teller effect and the BET theory have retained their original formulation and are still mainstays in physics and chemistry. Teller also made contributions to Thomas–Fermi theory, the precursor of density functional theory, a standard modern tool in the quantum mechanical treatment of complex molecules.  Teller's vigorous advocacy for strength through nuclear weapons, especially when so many of his wartime colleagues later expressed regret about the arms race, made him an easy target for the "mad scientist" stereotype. In 1991 he was awarded one of the first Ig Nobel Prizes for Peace in recognition of his "lifelong efforts to change the meaning of peace as we know it". He was also rumored to be one of the inspirations for the character of Dr. Strangelove in Stanley Kubrick's 1964 satirical film of the same name (others speculated to be RAND theorist Herman Kahn, mathematician John von Neumann, rocket scientist Wernher von Braun, and Secretary of Defense Robert McNamara). In the aforementioned "Scientific American" interview from 1999, he was reported as having bristled at the question: "My name is not Strangelove. I don't know about Strangelove. I'm not interested in Strangelove. What else can I say?... Look. Say it three times more, and I throw you out of this office." In one episode of "Mission Hill" (1999), a character appears to be inspired by Edward Teller. The character is very old, has pictures of himself and other scientists in his home office and is known as the father of the nuclear bomb.  Nobel Prize winning physicist Isidor I. Rabi once suggested that "It would have been a better world without Teller." In addition, Teller's false claims that Stanislaw Ulam made no significant contribution to the development of the hydrogen bomb (despite Ulam's key insights of using compression and staging elements to generate the thermonuclear reaction) and his personal attacks on Oppenheimer caused great animosity towards Teller within the general physics community.  In 1981, Teller became a founding member of the World Cultural Council.  In 1986, he was awarded the United States Military Academy's Sylvanus Thayer Award. He was elected a member of the U.S. National Academy of Sciences in 1948. He was a fellow of the American Academy of Arts and Sciences, the American Association for the Advancement of Science, and the American Nuclear Society. Among the honors he received were the Albert Einstein Award in 1958, the Golden Plate Award of the American Academy of Achievement in 1961, the Enrico Fermi Award in 1962, the Eringen Medal in 1980, the Harvey Prize in 1975, the National Medal of Science in 1983, the Presidential Citizens Medal in 1989, and the in 2001. He was also named as part of the group of "U.S. Scientists" who were "Time" magazine's People of the Year in 1960, and an asteroid, 5006 Teller, is named after him. He was awarded with the Presidential Medal of Freedom by President George W. Bush in 2003, less than two months before his death.  His final paper, published posthumously, advocated the construction of a prototype liquid fluoride thorium reactor. The genesis and impetus for this last paper, was recounted by the co-author Ralph Moir in 2007.

Edward Teller (; January 15, 1908 – September 9, 2003) was a Hungarian-American theoretical physicist who is known colloquially as "the father of the hydrogen bomb" (see the Teller–Ulam design), although he did not care for the title, and was only part of a team who developed the technology. Throughout his life, Teller was known both for his scientific ability and for his difficult interpersonal relations and volatile personality.

爱德华·泰勒(英语:Edward Teller,原匈牙利名为Teller Ede,1908年-1月15日-2003年-9月9日),出生于匈牙利的犹太裔理论物理学家,被誉为「氢弹之父」(见泰勒-乌拉姆构型),但他本人并不喜欢此称号。除氢弹之外,他对物理学多个领域都有相当的贡献。


History.

The Teutonic Knights were called to Koblenz by the Trier archbishop Theoderich von Wied in 1216 and vested with the estates around the Basilica of St. Castor located directly at the confluence of Mosel and Rhine. Serving mainly in nursing care, the knights soon after established a commandry ("Deutschordenskommende") here, which became the administrative seat of the Koblenz bailiwick directly subordinate to the Grand Master. The premises centred around the "Deutschherrenhaus" building were erected from 1279 onwards and became known as "Deutsches Eck".  About 1600, the Koblenz commander relocated his seat down the Rhine to Cologne. In 1794 the Left Bank of the Rhine was conquered by French revolutionary troops and the ecclesiastical estates secularised from 1802 onwards. The Order's premises were refurbished as part of the Prussian Koblenz Fortress. Later in the 19th century, the area was linked by a pier with a downstream sandbank creating the present-day headland.

Imperial iconography.

After the death of Emperor William I in 1888, his grandson William II wished to spark a nationalist cult around the "founder of the German Reich". In the following years the privately funded Kyffhäuser Monument was erected and an Emperor William Monument was inaugurated in Porta Westfalica, both designed by the Leipzig architect Bruno Schmitz. Several other cities had also applied as installation sites and in 1891 William II decided upon the confluence of the Rhine and Mosel rivers at Koblenz.  After further landfills at the site and a large-scale collection campaign, the official "Emperor William Monument of the Rhine Province" was erected and solemnly inaugurated in the presence of the emperor on 31 August 1897. Bruno Schmitz again had drawn up the plans for a giant, over high monument installed at the tip of the "Deutsches Eck", bearing an inscription quoting a verse by the Koblenz poet Max von Schenkendorf: "Nimmer wird das Reich zerstöret, wenn ihr einig seid und treu" ("Never will the Empire be destroyed, so long as you are united and loyal"). Another inscription could be found at the statue dedicating it to "Wilhelm der Große" ("William the Great"). The equestrian statue itself, in height, presented William I in a general's uniform, reminiscent of the Prussian victories in the "German Wars of Unification". His horse is roped by a winged female genius bearing a laurel wreath and the Imperial Crown.  After World War I under the terms of the Treaty of Versailles, the Rhine Province was occupied by Allied forces. When in November 1929 the area was finally cleared according to the Young Plan, tens of thousands gathered at the "Deutsches Eck" to celebrate the "liberation of the Rhineland". On 22 July 1930 Reich President Paul von Hindenburg celebrated the completion of his triumphal journey through the Rhenish lands here with a festive banquet and a firework display. Later in the same evening, 38 people were killed when a pontoon bridge across the Mosel collapsed under the weight of the crowds.

Demolition.

While the inner city of Koblenz was hit hard by Allied strategic bombing during World War II, the "Deutsches Eck" remained largely unscathed. On 16 March 1945, however, the statue was badly damaged by an American artillery shell. The Third US Army 87th Artillery unit led by Sergeant Loyd Watson fired upon it after the forward observer saw a German soldier depart from it. They assumed it was a base of operations and it was hit after three attempts. Soon afterwards it was completely taken down. The French military government planned to replace the old memorial with a monument for peace and understanding among nations, but that concept was never realized. After the formation of the Federal Republic of Germany and the German Democratic Republic in 1949, the country was divided into a capitalist west and a communist east. In order to express the deep wish for a united Germany, President Theodor Heuss turned the German Corner into a monument to German unity. As a result, the coats of arms of all German "Länder" (states), including those of former German territories such as Silesia, East Prussia and Pomerania, were installed. Replacing the destroyed equestrian statue, a German flag flew over the plaza.  After the Berlin Wall came down in November 1989, three concrete parts of the actual wall were installed next to the monument. On 3 October 1990, the emblems of the new federal states were added.

Reinstallation.

With German Reunification in 1990, the German Corner no longer served as a symbol of the aspiration for a united Germany. Thus, a discussion arose regarding a remodelling of the plaza. Critics considered the reinstallation of the equestrian statue of Wilhelm I as anachronistic and improper, whereas promoters saw the opportunity for tourist benefits. As the owner of the site, any decision to reinstall a statue of Wilhelm I rested with the government of the Rhineland-Palatinate. However, the state government transferred its rights to the city of Koblenz. When, a former newspaper publisher from Koblenz, and his wife Anneliese, announced that they would bear all costs for a reconstruction of the statue, the decision was made to proceed.  The Düsseldorf sculptor, Raymond Kittl, was commissioned to produce a replica of the original sculpture and the remodelled statue was created from durable bronze cast unlike the original which had been made from copper plates. In May 1992, the parts of the statue were brought to Koblenz on board the MS Futura. The assembly work was completed at the port and on 2 September 1993 a mobile lattice boom crane lifted the statue onto the base. The installation took place on Sedan Day, which although no longer officially recognized, was the day on which the German victory in the Battle of Sedan was commemorated. On 25 September 1993, the new statue was inaugurated.  Today, a big national flag and the flags of the 16 "Länder" are flying at the German Corner as a reminder of German unity. In addition the flag of the United States of America is displayed as a sign of support for the victims of the September 11 attacks. The three parts of the Berlin Wall are now dedicated to the "victims of the division".

Image gallery.

The Deutsches Eck is also a place on Germany's inland waterway system where great skill is needed when making a turn, as the following animation makes clear.

Deutsches Eck (, "German Corner") is the name of a headland in Koblenz, Germany, where the Mosel river joins the Rhine. Named after a local commandry of the Teutonic Order ("Deutscher Orden"), it became known for a monumental equestrian statue of William I, first German Emperor, erected in 1897 in appreciation for his role in the unification of Germany. One of many Emperor William monuments raised in the Prussian Rhine Province, it was destroyed in World War II and only the plinth was preserved as a memorial. Following German reunification, a replica of the statue was erected on the pedestal after controversial discussions in 1993. It is today a Koblenz landmark and a popular tourist destination.

德意志之角,又称德意志角或德国之角(德语:),是位于德国科布伦茨市摩泽尔河和莱茵河交汇处的一块陆地,建有一座宏伟的德意志帝国首任皇帝威廉一世铜制骑马雕塑。


History.

The fundamental principles of electricity generation were discovered in the 1820s and early 1830s by British scientist Michael Faraday. His method, still used today, is for electricity to be generated by the movement of a loop of wire, or Faraday disc, between the poles of a magnet. Central power stations became economically practical with the development of alternating current (AC) power transmission, using power transformers to transmit power at high voltage and with low loss.  Commercial electricity production started in 1870 with the coupling of the dynamo to the hydraulic turbine. The mechanical production of electric power began the Second Industrial Revolution and made possible several inventions using electricity, with the major contributors being Thomas Alva Edison and Nikola Tesla. Previously the only way to produce electricity was by chemical reactions or using battery cells, and the only practical use of electricity was for the telegraph.  Electricity generation at central power stations started in 1882, when a steam engine driving a dynamo at Pearl Street Station produced a DC current that powered public lighting on Pearl Street, New York. The new technology was quickly adopted by many cities around the world, which adapted their gas-fueled street lights to electric power. Soon after electric lights would be used in public buildings, in businesses, and to power public transport, such as trams and trains.  The first power plants used water power or coal. Today a variety of energy sources are used, such as coal, nuclear, natural gas, hydroelectric, wind, and oil, as well as solar energy, tidal power, and geothermal sources.

Methods of generation.

Several fundamental methods exist to convert other forms of energy into electrical energy. Utility-scale generation is achieved by rotating electric generators or by photovoltaic systems. A small proportion of electric power distributed by utilities is provided by batteries. Other forms of electricity generation used in niche applications include the triboelectric effect, the piezoelectric effect, the thermoelectric effect, and betavoltaics.

Generators.

Electric generators transform kinetic energy into electricity. This is the most used form for generating electricity and is based on Faraday's law. It can be seen experimentally by rotating a magnet within closed loops of conducting material (e.g. copper wire). Almost all commercial electrical generation is done using electromagnetic induction, in which mechanical energy forces a generator to rotate:

Electrochemistry.

Electrochemistry is the direct transformation of chemical energy into electricity, as in a battery. Electrochemical electricity generation is important in portable and mobile applications. Currently, most electrochemical power comes from batteries. Primary cells, such as the common zinc–carbon batteries, act as power sources directly, but secondary cells (i.e. rechargeable batteries) are used for storage systems rather than primary generation systems. Open electrochemical systems, known as fuel cells, can be used to extract power either from natural fuels or from synthesized fuels. Osmotic power is a possibility at places where salt and fresh water merge.

Photovoltaic effect.

The photovoltaic effect is the transformation of light into electrical energy, as in solar cells. Photovoltaic panels convert sunlight directly to DC electricity. Power inverters can then convert that to AC electricity if needed. Although sunlight is free and abundant, solar power electricity is still usually more expensive to produce than large-scale mechanically generated power due to the cost of the panels. Low-efficiency silicon solar cells have been decreasing in cost and multijunction cells with close to 30% conversion efficiency are now commercially available. Over 40% efficiency has been demonstrated in experimental systems. Until recently, photovoltaics were most commonly used in remote sites where there is no access to a commercial power grid, or as a supplemental electricity source for individual homes and businesses. Recent advances in manufacturing efficiency and photovoltaic technology, combined with subsidies driven by environmental concerns, have dramatically accelerated the deployment of solar panels. Installed capacity is growing by 40% per year led by increases in Germany, Japan, United States, China, and India.

Economics.

The selection of electricity production modes and their economic viability varies in accordance with demand and region. The economics vary considerably around the world, resulting in widespread residential selling prices, e.g. the price in Iceland is 5.54 cents per kWh while in some island nations it is 40 cents per kWh. Hydroelectric plants, nuclear power plants, thermal power plants and renewable sources have their own pros and cons, and selection is based upon the local power requirement and the fluctuations in demand. All power grids have varying loads on them but the daily minimum is the base load, often supplied by plants which run continuously. Nuclear, coal, oil, gas and some hydro plants can supply base load. If well construction costs for natural gas are below $10 per MWh, generating electricity from natural gas is cheaper than generating power by burning coal.  Thermal energy may be economical in areas of high industrial density, as the high demand cannot be met by local renewable sources. The effect of localized pollution is also minimized as industries are usually located away from residential areas. These plants can also withstand variation in load and consumption by adding more units or temporarily decreasing the production of some units. Nuclear power plants can produce a huge amount of power from a single unit. However, disasters in Japan have raised concerns over the safety of nuclear power, and the capital cost of nuclear plants is very high. Hydroelectric power plants are located in areas where the potential energy from falling water can be harnessed for moving turbines and the generation of power. It may not be an economically viable single source of production where the ability to store the flow of water is limited and the load varies too much during the annual production cycle.  Due to advancements in technology, and with mass production, renewable sources other than hydroelectricity (solar power, wind energy, tidal power, etc.) experienced decreases in cost of production, and the energy is now in many cases cost-comparative with fossil fuels. Many governments around the world provide subsidies to offset the higher cost of any new power production, and to make the installation of renewable energy systems economically feasible. However, their use is frequently limited by their intermittent nature; sometimes less than demand, sometimes more than transmission constraints allow, in which case their production may be curtailed.

Generating equipment.

Electric generators were known in simple forms from the discovery of electromagnetic induction in the 1830s. In general, some form of prime mover such as an engine or the turbines described above, drives a rotating magnetic field past stationary coils of wire thereby turning mechanical energy into electricity. The only commercial scale electricity production that does not employ a generator is solar PV.

Turbines.

Almost all commercial electrical power on Earth is generated with a turbine, driven by wind, water, steam or burning gas. The turbine drives a generator, thus transforming its mechanical energy into electrical energy by electromagnetic induction. There are many different methods of developing mechanical energy, including heat engines, hydro, wind and tidal power. Most electric generation is driven by heat engines. The combustion of fossil fuels supplies most of the energy to these engines, with a significant fraction from nuclear fission and some from renewable sources. The modern steam turbine (invented by Sir Charles Parsons in 1884) currently generates about 80% of the electric power in the world using a variety of heat sources. Turbine types include: Although turbines are most common in commercial power generation, smaller generators can be powered by gasoline or diesel engines. These may used for backup generation or as a prime source of power within isolated villages.

Production.

Total worldwide gross production of electricity in 2016 was 25,082 TWh. Sources of electricity were coal and peat 38.3%, natural gas 23.1%, hydroelectric 16.6%, nuclear power 10.4%, oil 3.7%, solar/wind/geothermal/tidal/other 5.6%, biomass and waste 2.3%.  Total energy consumed at all power plants for the generation of electricity was which was 36% of the total for primary energy sources (TPES) of 2008. Electricity output (gross) was, efficiency was 39%, and the balance of 61% was generated heat. A small part, or about 3% of the input total, of the heat was utilized at co-generation heat and power plants. The in-house consumption of electricity and power transmission losses were. The amount supplied to the final consumer was which was 33% of the total energy consumed at power plants and heat and power co-generation (CHP) plants.

Historical results of production of electricity.

Note that the vertical axes of these two charts are not to the same scale.

Production by country.

The United States has long been the largest producer and consumer of electricity, with a global share in 2005 of at least 25%, followed by China, Japan, Russia, and India. In 2011, China overtook the United States to become the largest producer of electricity.

List of countries with source of electricity 2005.

Data source of values (electric power generated) is IEA/OECD. Listed countries are top 20 by population or top 20 by GDP (PPP) and Saudi Arabia based on CIA World Factbook 2009.  Solar PV* is Photovoltaics Bio other* = 198 TWh (Biomass) + 69 TWh (Waste) + 4 TWh (other)

Environmental concerns.

Variations between countries generating electrical power affect concerns about the environment. In France only 10% of electricity is generated from fossil fuels, the US is higher at 70% and China is at 80%. The cleanliness of electricity depends on its source. Most scientists agree that emissions of pollutants and greenhouse gases from fossil fuel-based electricity generation account for a significant portion of world greenhouse gas emissions; in the United States, electricity generation accounts for nearly 40% of emissions, the largest of any source. Transportation emissions are close behind, contributing about one-third of U.S. production of carbon dioxide. In the United States, fossil fuel combustion for electric power generation is responsible for 65% of all emissions of sulfur dioxide, the main component of acid rain. Electricity generation is the fourth highest combined source of NOx, carbon monoxide, and particulate matter in the US. In July 2011, the UK parliament tabled a motion that "levels of (carbon) emissions from nuclear power were approximately three times lower per kilowatt hour than those of solar, four times lower than clean coal and 36 times lower than conventional coal".

Electricity generation is the process of generating electric power from sources of primary energy. For utilities in the electric power industry, it is the stage prior to its delivery to end users (transmission, distribution, etc.) or its storage (using, for example, the pumped-storage method).

发电(),泛指从其它种类的能源转换为电力的过程。 现今主要使用的发电基本原理,于公元1820～1830年间,由英国科学家麦可·法拉第所发现。法拉第电磁感应定律,借由一组以上的线圈在磁场中进行旋转运动,借以产生感应电流。


Earlier personifications.

The earliest known personification of the United States was as a woman named Columbia, who first appeared in 1738 (pre-USA) and sometimes was associated with another female personification, Lady Liberty. With the American Revolutionary War came Brother Jonathan, a male personification, and Uncle Sam finally appeared after the War of 1812. Columbia appeared with either Brother Jonathan or Uncle Sam, but her use declined as a national personification in favor of Liberty, and she was effectively abandoned once she became the mascot of Columbia Pictures in the 1920s.  According to an article in the 1893 "The Lutheran Witness", Uncle Sam was simply another name for Brother Jonathan:  When we meet him in politics we call him Uncle Sam; when we meet him in society we call him Brother Jonathan. Here of late Uncle Sam "alias" Brother Jonathan has been doing a powerful lot of complaining, hardly doing anything else. [sic]  A March 24, 1810 journal entry by Isaac Mayo (a midshipman in the United States Navy) states: weighed anchor stood down the harbour, passed Sandy Hook, where there are two light-houses, and put to sea, first and second day out most deadly seasick, oh could I have got on shore in the hight [sic] of it, I swear that uncle Sam, as they call him, would certainly forever have lost the services of at least one sailor.

Evolution.

The precise origin of the Uncle Sam character is unclear, but a popular legend is that the name "Uncle Sam" was derived from Samuel Wilson, a meatpacker from Troy, New York who supplied rations for American soldiers during the War of 1812. There was a requirement at the time for contractors to stamp their name and where the rations came from onto the food they were sending. Wilson's packages were labeled "E.A – US." When someone asked what that stood for, a co-worker jokingly said, "Elbert Anderson [the contractor] and Uncle Sam," referring to Wilson, though the "US" actually stood for United States. Doubts have been raised as to the authenticity of this story, as the claim did not appear in print until 1842. Additionally, the earliest known mention definitely referring to the metaphorical Uncle Sam is from 1810, predating Wilson's contract with the government. As early as 1835, Brother Jonathan made a reference to Uncle Sam, implying that they symbolized different things: Brother Jonathan was the country itself, while Uncle Sam was the government and its power.  By the 1850s, the names Brother Jonathan and Uncle Sam were being used nearly interchangeably, to the point that images of what had previously been called "Brother Jonathan" were being called "Uncle Sam". Similarly, the appearance of both personifications varied wildly. For example, one depiction of Uncle Sam in 1860 showed him looking like Benjamin Franklin, while a contemporaneous depiction of Brother Jonathan looks more like the modern version of Uncle Sam, though without a goatee.  Uncle Sam did not get a standard appearance, even with the effective abandonment of Brother Jonathan near the end of the American Civil War, until the well-known "recruitment" image of Uncle Sam was first created by James Montgomery Flagg during World War I. The image was inspired by a British recruitment poster showing Lord Kitchener in a similar pose. It is this image more than any other that has influenced the modern appearance of Uncle Sam: an elderly white man with white hair and a goatee, wearing a white top hat with white stars on a blue band, a blue tail coat, and red-and-white-striped trousers.  Flagg's depiction of Uncle Sam was shown publicly for the first time, according to some, on the cover of the magazine "Leslie's Weekly" on July 6, 1916, with the caption "What Are You Doing for Preparedness?" More than four million copies of this image were printed between 1917 and 1918. Flagg's image was also used extensively during World War II, during which the U.S. was codenamed "Samland" by the German intelligence agency Abwehr. The term was central in the song "The Yankee Doodle Boy", which was featured in 1942 in the musical "Yankee Doodle Dandy".  There are two memorials to Uncle Sam, both of which commemorate the life of Samuel Wilson: the Uncle Sam Memorial Statue in Arlington, Massachusetts, his birthplace; and a memorial near his long-term residence in Riverfront Park, Troy, New York. Wilson's boyhood home can still be visited in Mason, New Hampshire. Samuel Wilson died on July 31, 1854, aged 87, and is buried in Oakwood Cemetery, Troy, New York.  In 1989, "Uncle Sam Day" became official. A Congressional joint resolution designated September 13, 1989 as "Uncle Sam Day", the birthday of Samuel Wilson. In 2015, the family history company MyHeritage researched Uncle Sam's family tree and claims to have tracked down his living relatives.

Uncle Sam (initials U.S.) is a common national personification of the U.S. federal government or the country in general that, according to legend, came into use during the War of 1812 and was supposedly named for Samuel Wilson. The actual origin is by a legend. Since the early 19th century, Uncle Sam has been a popular symbol of the US government in American culture and a manifestation of patriotic emotion. While the figure of Uncle Sam represents specifically the government, Columbia represents the United States as a nation.

山姆大叔(英语:Uncle Sam)是美国的绰号和拟人化形象,一般被描绘成为穿着马甲礼服,头戴星条旗纹样的高礼帽、身材高瘦、留着山羊胡、帅气、精神矍铄的老人形象。此漫画形象由著名画家詹姆斯·蒙哥马利·弗拉格为公共资讯委员会绘画。


一九八四 (1984年电影)

Plot.

In a dystopian 1984, Winston Smith endures a squalid existence in the totalitarian superstate of Oceania under the constant surveillance of the Thought Police. Smith resides in London, the capital city of the territory of Airstrip One, formerly England. Winston works in a small office cubicle at the Ministry of Truth, rewriting history in accordance with the dictates of the Party and its supreme leader, Big Brother. Haunted by painful memories and restless desires, Winston keeps a secret diary of his private thoughts, thus creating evidence of his thoughtcrime. However, he tries to do it undercover of the telescreens, to maintain his safety.  His life takes a major turn when he is accosted by fellow Outer Party worker Julia and they begin an illicit affair. Their first meeting takes place in the remote countryside where they exchange subversive ideas before having sex. Shortly after, Winston rents a room above a pawn shop in the less restrictive proletarian area where they continue their liaison. Julia procures contraband food and clothing on the black market, and for a brief few months they secretly meet and enjoy an idyllic life of relative freedom and contentment together.  Their affair comes to an end one evening, with the sudden raid of the Thought Police; they are both arrested. It is later revealed that their transgressions were recorded by a hidden telescreen in their room and that the proprietor of the pawn shop Mr. Charrington is a covert agent of the Thought Police. Winston and Julia are taken away to the Ministry of Love to be detained, questioned and "rehabilitated" separately. There O'Brien, a high-ranking member of the Inner Party, systematically tortures him.  O'Brien instructs Winston about the state's true purpose and schools him in a kind of catechism on the principles of "doublethink" — the practice of holding two contradictory thoughts in the mind simultaneously. For his final rehabilitation, Winston is brought to Room 101, where O'Brien tells him he will be subjected to the "worst thing in the world", designed specifically around Smith's personal phobias. When confronted with this unbearable horror — which turns out to be a cage filled with wild rats — Winston's psychological resistance finally and irretrievably breaks down, and he hysterically repudiates his allegiance to Julia. Now completely subjugated and purged of any rebellious thoughts, impulses, or personal attachments, Winston is restored to physical health and released.  Winston returns to the Chestnut Tree Café, where he had previously seen the rehabilitated thought criminals Jones, Aaronson and Rutherford (themselves once prominent but later disgraced members of the Inner Party) who have since been "vaporized" and rendered unpersons. While sitting at the chess table, Winston is approached by Julia, who was similarly "rehabilitated". They share a bottle of Victory Gin and impassively exchange a few words about how they have betrayed each other. They act indifferently towards each other. After she leaves, Winston watches a broadcast of himself on the large telescreen confessing his "crimes" against the state and imploring forgiveness from the populace.  Upon hearing a news report declaring the Oceanian army's utter rout of the enemy (Eurasia)'s forces in North Africa, Winston looks at the still image of Big Brother that appears on the telescreen, then turns away with tears in his eyes as the words "I love you" are heard whispered in his voice.  Annie Lennox makes a cameo appearance as a woman at the Two Minutes Hate rally.

Production.

In winter 1983, the director Michael Radford asked his producer to try to obtain the rights to Orwell's novel, with low expectations that they were available. It turned out that the rights were held by Marvin Rosenblum, a Chicago lawyer who had been trying on his own to get such a film produced. Rosenblum agreed to become an executive producer, and while producer Simon Perry raised the production money from Richard Branson, Radford wrote the script, inspired by his idea to make a "science fiction film made in 1948." The script was finished in three weeks.  For the role of O'Brien, Paul Scofield was originally contracted to play the part, but had to withdraw after sustaining a broken leg while filming "The Shooting Party". Anthony Hopkins, Sean Connery and Rod Steiger were all then considered. Richard Burton, who was living in Haiti, joined the production six weeks into its shooting schedule and insisted on his costume of a boiler suit being hand-made for him in Savile Row.  Some internet sources claim that principal photography began on 19 March 1984 and ended in October 1984. However the film was released that same month, and a title card at the end of the film explicitly states, it "was photographed in and around London during the period April–June 1984, the exact time and setting imagined by the author." The budget was originally £2.5 million but this rose during filming and additional funds were required. The opening scenes of the film showing the Two Minutes Hate were filmed in a grass-covered hangar at RAF Hullavington near Chippenham in Wiltshire. Some scenes set in Victory Square were also filmed at Alexandra Palace in London. Senate House (University of London) was used for exterior shots of the Ministry of Truth.  The disused Battersea Power Station in Wandsworth served as the façade for the Victory Mansions; and the Beckton Gas Works in the Docklands of Newham was used as the setting for the proletarian zones. The pawnshop exterior, a pub scene and a scene with a prostitute were filmed in Cheshire Street, in London's East End, an area Orwell had visited and commented on in his first book, "Down and Out in Paris and London". The canteen interiors were filmed in a disused grain mill at Silvertown. In contrast, the idyllic, dreamlike "Golden Country", where Winston and Julia repair for their first tryst and which recurs in Winston's fantasies, was filmed in the southwest county of Wiltshire at a natural circle of hills called "The Roundway", near the town of Devizes. The scenes on the train were shot on the Kent and East Sussex Railway. The film shared a number of locations with Terry Gilliam's "Brazil", which was filmed the same year.  Radford and cinematographer Roger Deakins originally wanted to shoot the film in black and white, but the financial backers of the production, Virgin Films, opposed this idea. Instead, Deakins used a film processing technique called bleach bypass (originally created by Technicolor and Deluxe, but recreated for this production by Key) to create the distinctive washed-out look of the film's colour visuals. The film is a very rare example of the technique being applied to every release print, rather than the interpositive, that was struck from the original camera negative, or the internegative (struck from the interpositive); as the silver is retained in the print and cannot be reclaimed by the lab, the cost is higher, but the retained silver gives a "depth" to the projected image.

Reception.

The film was released in the United States for one week in December 1984 at the Egyptian Theatre in Los Angeles to qualify for the 1984 Academy Awards and grossed a house record $62,121, despite stormy weather.  Vincent Canby of The New York Times said the film was "admirable, bleakly beautiful", although "not an easy film to watch".  Roger Ebert awarded the film 3.5/4 stars, writing that it "penetrates much more deeply into the novel's heart of darkness" than previous adaptations, and describing Hurt as "the perfect Winston Smith".  Review aggregation website Rotten Tomatoes has given the film a 76% "fresh" rating, based on 25 reviews, with an average rating of 6.81/10. The site's critical consensus states: ""1984" doesn't fully emerge from the shadow of its source material, but still proves a solid, suitably discomfiting adaptation of a classic dystopian tale."  Metacritic has given the film a rating of 67 out of 100 based on 8 critics, indicating "generally favorable reviews".

Score controversy.

Virgin Films (formerly part of the Virgin Group), who financed the film, commissioned the British rock/pop duo Eurythmics to produce the music for the soundtrack. Radford objected to Virgin's insistence on using the more pop-oriented electronic Eurythmics music, as the traditional orchestral score originally intended for the film had been composed entirely by Dominic Muldowney a few months earlier.  Against Radford's wishes, Virgin exercised their right of final cut and replaced Muldowney's musical cues with the new Eurythmics contributions. One Eurythmics song, "Julia", was also heard in its entirety during the film's closing credits. However, Muldowney's main theme music (particularly the state anthem, "Oceania, 'tis for thee") was still prominently featured in the film. In November 1984, Virgin Records released the Eurythmics soundtrack album, featuring considerably altered versions of their music heard in the film, under the title "1984 (For the Love of Big Brother)". The album reached number 23 on the UK Album Chart, and was later certified Gold by the BPI for sales in excess of 100,000 copies. A song from the album, "Sexcrime (Nineteen Eighty-Four)", was released as a single just prior to the album and became one of Eurythmics' biggest hits, peaking at number 4 and was awarded a Silver disc for sales in excess of 200,000 copies. The music video for the single featured clips from the film. The track "Julia" was also released as a single which peaked just outside the Top 40.  During his acceptance speech at the "Evening Standard" British Film Awards, Radford expressed his displeasure with Virgin's decision and claimed that the Eurythmics music had been "foisted" on his film. Radford had disowned Virgin's edit of the film featuring the mixed Eurythmics/Muldowney score, yet when "Nineteen Eighty-Four" made its theatrical debut on 10 October in London by 20th Century Fox and on 14 December in New York City by Atlantic Releasing Corporation, this was the version released in wide circulation. Michael Radford withdrew the film from consideration at the BAFTA awards in protest of Virgin's decision to change the musical score. Eurythmics responded with a statement of their own claiming no knowledge of prior agreements between Virgin and Radford/Muldowney and that they had accepted the offer to compose music for the film in good faith.  In 1999, Muldowney's complete orchestral score (24 tracks in total) was released on a special limited edition CD album under the title "Nineteen Eighty-Four: The Music of Oceania", to commemorate the film's 15th anniversary. The CD booklet featured previously unseen production photographs and artwork as well as liner notes by Radford.  This has carried over to some home video releases of the film, as of today, Metro-Goldwyn-Mayer owns the film's rights worldwide since they own both the Atlantic Releasing Corporation and the Virgin Films catalogs, and on their DVD release in North America in 2003, the film's colour is restored to a normal level of saturation and the Eurythmics contributions to the score were removed entirely and replaced with Muldowney's musical cues as Radford had originally intended—although both Eurythmics and Muldowney are still jointly credited in the opening and closing titles. This DVD release was quickly discontinued and currently remains out of print. This version had previously been shown by Channel 4 in the UK in the late-1980s. However, while the MGM DVD release of the film in the UK in 2004 features the desaturated visuals, it has the mixed Eurythmics/Muldowney soundtrack on the English- and French-language audio tracks, but the purely Muldowney soundtrack on the German- and Spanish-language audio tracks.  In 2013 the film was re-released on DVD in North America by TGG Direct on a double feature with "Megaville" (1990), under license from MGM. This DVD release also features the original mix of Eurythmics/Muldowney soundtracks, as well as the theatrical desaturated colour palette. In 2015 the film was released on Blu-ray in North America by Twilight Time in a limited 3,000 copy run, again, licensed by MGM. This release features the Eurythmics/Muldowney Soundtrack on one audio channel and Muldowney's orchestral score on another, as well as keeping true to the original colour scheme.  The version of the film which has been released on Digital Download services is the 2015 HD edition. It is available only with the original Eurythmics/Muldowney soundtrack.  The 2019 Criterion Collection release of the film contains both the Eurythmics soundtrack and the original score composed by Dominic Muldowney.

Awards.

The film won the Best British Film of the Year award at the Evening Standard British Film Awards. It also won The Golden Tulip Award at the 1985 Istanbul International Film Festival.

Home media.

International Video Entertainment paid $2 million for North American home video rights, the fifth biggest deal ever at the time.

Nineteen Eighty-Four, also known as 1984, is a 1984 British dystopian science fiction film written and directed by Michael Radford, based upon George Orwell's 1949 novel of the same name. Starring John Hurt, Richard Burton, Suzanna Hamilton, and Cyril Cusack, the film follows the life of Winston Smith, a low-ranking civil servant in a war-torn London ruled by Oceania, a totalitarian superstate. Smith (Hurt) struggles to maintain his sanity and his grip on reality as the regime's overwhelming power and influence persecutes individualism and individual thinking on both a political and personal level.

《一九八四》(英语:Nineteen Eighty-Four,又称《1984》)是一部英国反乌托邦电影,由迈克尔·雷德福导演和编剧,根据乔治·奥威尔的同名小说改编。影片讲述了温斯顿·史密斯在极权主义国家一九八四中的国家的生活,由约翰·赫特、苏珊娜·汉密尔顿和理乍得·伯顿主演。


Adoption.

History of multitenant applications.

Multitenant applications have evolved from—and combine some characteristics of—three types of services:

Differentiation from virtualization.

In a multitenancy environment, multiple customers share the same application, running on the same operating system, on the same hardware, with the same data-storage mechanism. The distinction between the customers is achieved during application design, thus customers do not share or see each other's data. Compare this with virtualization where components are transformed, enabling each customer application to appear to run on a separate virtual machine.

Competitive differentiation.

Some companies actively promote the principle of multitenancy and use it as a source of competitive differentiation. The use of multitenancy is increasing day by day.

Economics of multitenancy.

Cost savings.

Multitenancy allows for cost savings over and above the basic economies of scale achievable from consolidating IT resources into a single operation. An application instance usually incurs a certain amount of memory and processing overhead which can be substantial when multiplied by many customers, especially if the customers are small. Multitenancy reduces this overhead by spreading it over many customers. Further cost savings may come from licensing costs of the underlying software (such as operating systems and database management systems). Put crudely, if you can run everything on a single software instance, you only have to buy one software license. The cost savings can be eclipsed by the difficulty of scaling the single instance as demand grows - increasing the performance of the instance on a single server can only be done by buying faster hardware, such as fast CPUs, more memory, and faster disk systems, and typically these costs grow faster than if the load was split between multiple servers with roughly the same aggregate capacity. In addition, development of multitenant systems is more complex, and security testing is more stringent owing to the fact that multiple customers' data is being commingled.

Data aggregation/data mining.

One of the most compelling reasons for vendors/ISVs to utilize multitenancy is for the inherent data aggregation benefits. Instead of collecting data from multiple data sources, with potentially different database schemas, all data for all customers is stored in a single database schema. Thus, running queries across customers, mining data, and looking for trends is much simpler. This reason is probably overhyped as one of the core multitenancy requirements is the need to prevent Service Provider access to customer (tenant) information. Further, it is common to separate the operational database from the mining database (usually because of different workload characteristics), thus weakening the argument even more.

Complexity.

Because of the additional customization complexity and the need to maintain per-tenant metadata, multitenant applications require a larger development effort. Considerations such as vector-based data sequencing, encryptable algorithm infrastructure, and virtualized control interfaces, must be taken into account.

Release management.

Multitenancy simplifies the release management process. In a traditional release management process, packages containing code and database changes are distributed to client desktop and/or server machines; in the single-instance case, this would be one server machine per customer. These packages then have to be installed on each individual machine. With the multitenant model, the package typically only needs to be installed on a single server. This greatly simplifies the release management process, and the scale is no longer dependent on the number of customers.  At the same time, multitenancy increases the risks and impacts inherent in applying a new release version. As there is a single software instance serving multiple tenants, an update on this instance may cause downtime for all tenants even if the update is requested and useful for only one tenant. Also, some bugs and issues resulted from applying the new release could manifest in other tenants' personalized view of the application. Because of possible downtime, the moment of applying the release may be restricted depending on time usage schedule of more than one tenant.

Requirements.

Customization.

Multitenant applications are typically required to provide a high degree of customization to support each target organization's needs. Customization typically includes the following aspects:

Quality of service.

Multitenant applications are expected to provide adequate isolation of security, robustness and performance between multiple tenants which is provided by the layers below the application in case of multi-instance applications.

Virtualization.

The costs of redesigning applications for multitenancy can be significant, especially for software vendors who continue to offer an on-premises single tenant version of their product. They end up being forced to support two distinct products with all the resulting costs.  An increasingly viable alternative route to multitenancy that eliminates the need for significant architectural change is to use virtualization technology to host multiple isolated instances of an application on one or more servers. Indeed, when applications are repackaged as virtual appliances the same appliance image can be deployed in ISV hosted, on-premises or trusted-third party locations and even migrated from one deployment site to another over time.

The term "software multitenancy" refers to a software architecture in which a single instance of software runs on a server and serves multiple tenants. Systems designed in such manner are often called shared (in contrast to dedicated or isolated). A tenant is a group of users who share a common access with specific privileges to the software instance. With a multitenant architecture, a software application is designed to provide every tenant a dedicated share of the instance - including its data, configuration, user management, tenant individual functionality and non-functional properties. Multitenancy contrasts with multi-instance architectures, where separate software instances operate on behalf of different tenants. Some commentators regard multitenancy as an important feature of cloud computing.

多租户技术(英语:multi-tenancy technology)或称多重租赁技术,是一种软件架构技术,它是在探讨与实作如何于多用户的环境下共享相同的系统或程序元件,并且仍可确保各用户间资料的隔离性。


Types and usage.

Chemistry.

Test tubes,intended for general chemical work, are usually made of glass, for its relative resistance to heat. Tubes made from expansion-resistant glasses, mostly borosilicate glass (or fused quartz) can withstand high temperatures, up to several hundred degrees Celsius.  Chemistry tubes are available in a multitude of lengths and widths, typically from 10 to 20 mm wide and 50 to 200 mm long. The top often features a flared lip to aid pouring out the contents.  A chemistry test tube typically has a flat bottom, a round bottom, or a conical bottom. Some test tubes are made to accept a ground glass stopper or a screw cap. They are often provided with a small ground glass or white glaze area near the top for labelling with a pencil.  Test tubes are widely used by chemists to handle chemicals, especially for qualitative experiments and assays. Their spherical bottom and vertical sides reduce mass loss when pouring, make them easier to wash out, and allow convenient monitoring of the contents. The long, narrow neck of test tube slows down the spreading of gases to the environment.  Test tubes are convenient containers for heating small amounts of liquids or solids with a Bunsen burner or alcohol burner. The tube is usually held by its neck with a clamp or tongs. By tilting the tube, the bottom can be heated to hundreds of degrees in the flame, while the neck remains relatively cool, possibly allowing vapours to condense on its walls. A boiling tube is a large test tube intended specifically for boiling liquids.  A test tube filled with water and upturned into a water-filled beaker is often used to capture gases, e.g. in electrolysis demonstrations.  A test tube with a stopper is often used for temporary storage of chemical or biological samples.

Biosciences.

Culture tubes are test tubes used in biology and related sciences for handling and culturing all kinds of live organisms, such as molds, bacteria, seedlings, plant cuttings, etc.. Some racks for culture tubes are designed to hold the tubes in a nearly horizontal position, so as to maximize the surface of the culture medium inside.  Culture tubes for biology are usually made of clear plastic (such as polystyrene or polypropylene) by injection molding and are often discarded after use. Plastic test tubes with a screwtop cap are often called "Falcon tubes" after a line manufactured by Becton Dickinson.  Some sources consider that the presence of a lip is what distinguishes a test tube from a culture tube.

Clinical medicine.

In clinical medicine, sterile test tubes with air removed, called vacutainers, are used to collect and hold samples of physiological fluids such as blood, urine, pus, and synovial fluid. These tubes are commonly sealed with a rubber stopper and often have a specific additive placed in the tube with the stopper color indicating the additive. For example, a "blue-top tube" is a 5 ml test tube containing sodium citrate as an anticoagulant, used to collect blood for coagulation and glucose-6-phosphate dehydrogenase testing. Small vials used in medicine may have a snap-top (also called a hinge cap) moulded as part of the vial.

Other uses.

Test tubes are sometimes put to casual uses outside of lab environments, e.g. as flower vases, glassware for certain weak shots, or containers for spices. They can also be used for raising queen ants during their first months of development.

Variants.

Boiling tube.

A boiling tube is a small cylindrical vessel used to strongly heat substances in the flame of a Bunsen burner. A boiling tube is essentially a scaled-up test tube, being about 50% larger.  They are designed to be wide enough to allow substances to boil violently as opposed to a test tube, which is too narrow; a boiling liquid can explode out of the end of test tubes when they are heated, as there is no room for bubbles of gas to escape independently of the surrounding liquid. This phenomenon is called bumping.

Ignition tube.

An ignition tube is used in much the same way as a boiling tube, except it is not as large and thick-walled. It is primarily used to hold small quantities of substances which are undergoing direct heating by a Bunsen burner or other heat source. This type of tube is used in the sodium fusion test.  Ignition tubes are often difficult to clean due to the small bore. When used to heat substances strongly, some char may stick to the walls as well. They are usually disposable.

A test tube, also known as a culture tube or sample tube, is a common piece of laboratory glassware consisting of a finger-like length of glass or clear plastic tubing, open at the top and closed at the bottom.

试管(Test tube)是一种实验室玻璃器皿。常见的试管种类有平口试管、卷口试管、具支试管、具刻度试管、具塞试管、具塞刻度试管。