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98-467: Before its use as a hospital, the buildings formed the Langwood Hotel , operated during the 1880s by George F. Butterfield. Dr. Linda Goudey, an obstetrician who worked at New England Memorial Hospital, was strangled to death in her car in the hospital's parking lot. 42°27′06″N 71°05′21″W  /  42.4518°N 71.0891°W  / 42.4518; -71.0891 This article relating to

196-422: A gestational sac , yolk sac , and fetal pole . The gestational age can be assessed by evaluating the mean gestational sac diameter (MGD) before week 6, and the crown-rump length after week 6. Multiple gestation is evaluated by the number of placentae and amniotic sacs present. Other tools used for assessment include: A pregnant woman may have a pre-existing disease , that may become worse or become

294-406: A hospital may leave the hospital as soon as she is medically stable, and chooses to leave, which can be as early as a few hours later, but usually averages a stay of one or two days; the average postnatal stay following delivery by caesarean section is three to four days. During this time the mother is monitored for bleeding , bowel and bladder function, and baby care. The infant 's health

392-583: A nuclear reactor , where a metres-thick water layer is used as effective shielding. There are two sources of high energy particles entering the Earth's atmosphere from outer space: the sun and deep space. The sun continuously emits particles, primarily free protons, in the solar wind, and occasionally augments the flow hugely with coronal mass ejections (CME). The particles from deep space (inter- and extra-galactic) are much less frequent, but of much higher energies. These particles are also mostly protons, with much of

490-517: A body to a point high enough to ionize small fractions of atoms or molecules by the process of thermal-ionization (this, however, requires relatively extreme radiation intensities). As noted above, the lower part of the spectrum of ultraviolet, called soft UV, from 3 eV to about 10 eV, is non-ionizing. However, the effects of non-ionizing ultraviolet on chemistry and the damage to biological systems exposed to it (including oxidation, mutation, and cancer) are such that even this part of ultraviolet

588-412: A controversial medical past. Under the beliefs at the time about pain and the prejudice towards African people, he had practiced his surgical skills and developed skills on slaves. These women were the first patients of modern gynecology. One of the women he operated on was named Anarcha Westcott , the woman he first treated for a fistula. Women and men inhabited very different roles in natal care up to

686-483: A delivery reduced childbed fever fatalities by 90%. So it was concluded that it was physicians who had been spreading disease from one labouring mother to the next. Despite the publication of this information, doctors still would not wash. It was not until the 20th century when advancements in aseptic technique and the understanding of disease would play a significant role in the decrease of maternal mortality rates among many populations. The development of obstetrics as

784-613: A fluorescence on a nearby plate of coated glass. Within a month, he discovered the main properties of X-rays that we understand to this day. In 1896, Henri Becquerel found that rays emanating from certain minerals penetrated black paper and caused fogging of an unexposed photographic plate. His doctoral student Marie Curie discovered that only certain chemical elements gave off these rays of energy. She named this behavior radioactivity . Alpha rays (alpha particles) and beta rays ( beta particles ) were differentiated by Ernest Rutherford through simple experimentation in 1899. Rutherford used

882-402: A generic pitchblende radioactive source and determined that the rays produced by the source had differing penetrations in materials. One type had short penetration (it was stopped by paper) and a positive charge, which Rutherford named alpha rays . The other was more penetrating (able to expose film through paper but not metal) and had a negative charge, and this type Rutherford named beta . This

980-465: A health hazard if used improperly. Exposure to radiation causes damage to living tissue; high doses result in Acute radiation syndrome (ARS), with skin burns, hair loss, internal organ failure, and death, while any dose may result in an increased chance of cancer and genetic damage ; a particular form of cancer, thyroid cancer , often occurs when nuclear weapons and reactors are the radiation source because of

1078-409: A higher orbital level or if the photon is extremely energetic, it may knock an electron from the atom altogether, causing the atom to ionize. Generally, larger atoms are more likely to absorb an X-ray photon since they have greater energy differences between orbital electrons. The soft tissue in the human body is composed of smaller atoms than the calcium atoms that make up bone, so there is a contrast in

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1176-511: A hospital in Massachusetts is a stub . You can help Misplaced Pages by expanding it . This Seventh-day Adventist -related article is a stub . You can help Misplaced Pages by expanding it . Obstetrics Obstetrics is the field of study concentrated on pregnancy , childbirth and the postpartum period . As a medical specialty , obstetrics is combined with gynecology under the discipline known as obstetrics and gynecology (OB/GYN), which

1274-447: A lever for the introduction of men into an arena previously managed and run by women – midwifery. The addition of the male-midwife (or man-midwife) is historically a significant change to the profession of obstetrics. In the 18th century medical men began to train in area of childbirth and believed with their advanced knowledge in anatomy that childbirth could be improved. In France these male-midwives were referred to as accoucheurs ,

1372-617: A practice for accredited doctors happened at the turn of the 18th century and thus was very differently developed in Europe and in the Americas due to the independence of many countries in the Americas from European powers. "Unlike in Europe and the British Isles, where midwifery laws were national, in America, midwifery laws were local and varied widely". Gynaecology and Obstetrics gained attention in

1470-440: A risk to the pregnancy, or to postnatal development of the offspring Induction is a method of artificially or prematurely stimulating labour in a woman. Reasons to induce can include pre-eclampsia , foetal distress, placental malfunction, intrauterine growth retardation and failure to progress through labour increasing the risk of infection and foetal distresses. Induction may be achieved via several methods: During labour,

1568-411: A serious complication had taken place and the midwife had exhausted all measures at her disposal. Calling a surgeon was very much a last resort and having men deliver women in this era was seen as offending female modesty. Prior to the 18th and 19th centuries, midwifery was well established but obstetrics was not recognized as a specific medical specialty. However, the subject matter and interest in

1666-462: A significant degree, and is sometimes referred to as vacuum ultraviolet . Although present in space, this part of the UVA spectrum is not of biological importance, because it does not reach living organisms on Earth. There is a zone of the atmosphere in which ozone absorbs some 98% of non-ionizing but dangerous UV-C and UV-B. This ozone layer starts at about 20 miles (32 km) and extends upward. Some of

1764-453: A surgical practice in 1795 and performed the first ovariotomy in 1809 on a 47-year-old widow who then lived on for 31 more years. He had attempted to share this with John Bell whom he had practiced under who had retired to Italy. Bell was said to have died without seeing the document but it was published by an associate in Extractions of Diseased Ovaria in 1825. By the mid-century the surgery

1862-414: A temperature at or below room temperature would thus appear absolutely black, as it would not reflect any incident light nor would it emit enough radiation at visible wavelengths for our eyes to detect. Theoretically, a black-body emits electromagnetic radiation over the entire spectrum from very low frequency radio waves to x-rays, creating a continuum of radiation. The color of a radiating black-body tells

1960-461: A title later used all over Europe. The founding of lying-in hospitals also contributed to the medicalization and male-dominance of obstetrics. These early maternity hospitals were establishments where women would come to have their babies delivered, as opposed to the practice since time immemorial of the midwife attending the home of the woman in labour. This institution provided male-midwives with endless patients to practice their techniques on and

2058-629: A violent part of the universe's early history. The kinetic energy of particles of non-ionizing radiation is too small to produce charged ions when passing through matter. For non-ionizing electromagnetic radiation (see types below), the associated particles (photons) have only sufficient energy to change the rotational, vibrational or electronic valence configurations of molecules and atoms. The effect of non-ionizing forms of radiation on living tissue has only recently been studied. Nevertheless, different biological effects are observed for different types of non-ionizing radiation. Even "non-ionizing" radiation

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2156-450: A wavelength less than about 10  m (greater than 3 × 10  Hz and 1240 eV ). A smaller wavelength corresponds to a higher energy according to the equation E = h c / λ . ( E is Energy; h is the Planck constant; c is the speed of light; λ is wavelength.) When an X-ray photon collides with an atom, the atom may absorb the energy of the photon and boost an electron to

2254-403: Is a common synonym for infrared radiation emitted by objects at temperatures often encountered on Earth. Thermal radiation refers not only to the radiation itself, but also the process by which the surface of an object radiates its thermal energy in the form of black-body radiation. Infrared or red radiation from a common household radiator or electric heater is an example of thermal radiation, as

2352-413: Is a surgical field. Prenatal care is important in screening for various complications of pregnancy . This includes routine office visits with physical exams and routine lab tests along with telehealth care for people with low-risk pregnancies: Routine tests in the first trimester of pregnancy generally include: Genetic screening for Down syndrome (trisomy 21) and Edwards syndrome (trisomy 18),

2450-486: Is also ionizing. Neutrons are categorized according to their speed/energy. Neutron radiation consists of free neutrons . These neutrons may be emitted during either spontaneous or induced nuclear fission. Neutrons are rare radiation particles; they are produced in large numbers only where chain reaction fission or fusion reactions are active; this happens for about 10 microseconds in a thermonuclear explosion, or continuously inside an operating nuclear reactor; production of

2548-423: Is also monitored. Prior to the 18th century, caring for pregnant women in Europe was confined exclusively to women , and rigorously excluded men. The expectant mother would invite close female friends and family members to her home to keep her company during childbirth . Skilled midwives managed all aspects of the labour and delivery. The presence of physicians and surgeons was very rare and only occurred if

2646-408: Is also used for detecting congenital anomalies (or other foetal anomalies) and determining the biophysical profiles (BPP), which are generally easier to detect in the second trimester when the foetal structures are larger and more developed. X-rays and computerized tomography (CT) are not used, especially in the first trimester, due to the ionizing radiation , which has teratogenic effects on

2744-610: Is aware of uncertainties and lack of precision of the models and parameter values", "Collective effective dose is not intended as a tool for epidemiological risk assessment, and it is inappropriate to use it in risk projections" and "in particular, the calculation of the number of cancer deaths based on collective effective doses from trivial individual doses should be avoided". Ultraviolet, of wavelengths from 10 nm to 125 nm, ionizes air molecules, causing it to be strongly absorbed by air and by ozone (O 3 ) in particular. Ionizing UV therefore does not penetrate Earth's atmosphere to

2842-841: Is broken. This leads to production of chemical free radicals . In addition, very high energy neutrons can cause ionizing radiation by "neutron spallation" or knockout, wherein neutrons cause emission of high-energy protons from atomic nuclei (especially hydrogen nuclei) on impact. The last process imparts most of the neutron's energy to the proton, much like one billiard ball striking another. The charged protons and other products from such reactions are directly ionizing. High-energy neutrons are very penetrating and can travel great distances in air (hundreds or even thousands of metres) and moderate distances (several metres) in common solids. They typically require hydrogen rich shielding, such as concrete or water, to block them within distances of less than 1 m. A common source of neutron radiation occurs inside

2940-474: Is capable of causing thermal-ionization if it deposits enough heat to raise temperatures to ionization energies. These reactions occur at far higher energies than with ionization radiation, which requires only single particles to cause ionization. A familiar example of thermal ionization is the flame-ionization of a common fire, and the browning reactions in common food items induced by infrared radiation, during broiling-type cooking. The electromagnetic spectrum

3038-404: Is composed of photons, which have neither mass nor electric charge and, as a result, penetrates much further through matter than either alpha or beta radiation. Gamma rays can be stopped by a sufficiently thick or dense layer of material, where the stopping power of the material per given area depends mostly (but not entirely) on the total mass along the path of the radiation, regardless of whether

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3136-476: Is conserved (in vacuum), the intensity of all types of radiation from a point source follows an inverse-square law in relation to the distance from its source. Like any ideal law, the inverse-square law approximates a measured radiation intensity to the extent that the source approximates a geometric point. Radiation with sufficiently high energy can ionize atoms; that is to say it can knock electrons off atoms, creating ions. Ionization occurs when an electron

3234-534: Is electromagnetic radiation with a wavelength between 0.7 and 300 μm, which corresponds to a frequency range between 430 and 1 THz respectively. IR wavelengths are longer than that of visible light, but shorter than that of microwaves. Infrared may be detected at a distance from the radiating objects by "feel". Infrared sensing snakes can detect and focus infrared by use of a pinhole lens in their heads, called "pits". Bright sunlight provides an irradiance of just over 1 kW/m at sea level. Of this energy, 53%

3332-411: Is infrared radiation, 44% is visible light, and 3% is ultraviolet radiation. Microwaves are electromagnetic waves with wavelengths ranging from as short as 1 mm to as long as 1 m, which equates to a frequency range of 300 MHz to 300 GHz. This broad definition includes both UHF and EHF (millimetre waves), but various sources use different other limits. In all cases, microwaves include

3430-408: Is made of trillions of atoms, only a small fraction of those will be ionized at low to moderate radiation powers. The probability of ionizing radiation causing cancer is dependent upon the absorbed dose of the radiation and is a function of the damaging tendency of the type of radiation ( equivalent dose ) and the sensitivity of the irradiated organism or tissue ( effective dose ). If the source of

3528-403: Is more penetrating than alpha radiation but less than gamma. Beta radiation from radioactive decay can be stopped with a few centimetres of plastic or a few millimetres of metal. It occurs when a neutron decays into a proton in a nucleus, releasing the beta particle and an antineutrino . Beta radiation from linac accelerators is far more energetic and penetrating than natural beta radiation. It

3626-543: Is naturally present in the environment, since most rocks and soil have small concentrations of radioactive materials. Since this radiation is invisible and not directly detectable by human senses, instruments such as Geiger counters are usually required to detect its presence. In some cases, it may lead to secondary emission of visible light upon its interaction with matter, as in the case of Cherenkov radiation and radio-luminescence. Ionizing radiation has many practical uses in medicine, research, and construction, but presents

3724-689: Is often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles. Ionizing radiation carries more than 10 electron volts (eV) , which is enough to ionize atoms and molecules and break chemical bonds . This is an important distinction due to the large difference in harmfulness to living organisms. A common source of ionizing radiation is radioactive materials that emit α, β, or γ radiation , consisting of helium nuclei , electrons or positrons , and photons , respectively. Other sources include X-rays from medical radiography examinations and muons , mesons , positrons, neutrons and other particles that constitute

3822-409: Is often compared with ionizing radiation. Light, or visible light, is a very narrow range of electromagnetic radiation of a wavelength that is visible to the human eye, or 380–750 nm which equates to a frequency range of 790 to 400 THz respectively. More broadly, physicists use the term "light" to mean electromagnetic radiation of all wavelengths, whether visible or not. Infrared (IR) light

3920-721: Is radiation frequencies from 3 to 30 Hz (10 to 10  m respectively). In atmosphere science, an alternative definition is usually given, from 3 Hz to 3 kHz. In the related magnetosphere science, the lower frequency electromagnetic oscillations (pulsations occurring below ~3 Hz) are considered to lie in the ULF range, which is thus also defined differently from the ITU Radio Bands. A massive military ELF antenna in Michigan radiates very slow messages to otherwise unreachable receivers, such as submerged submarines. Thermal radiation

4018-531: Is sometimes used therapeutically in radiotherapy to treat superficial tumors. Beta-plus (β ) radiation is the emission of positrons , which are the antimatter form of electrons. When a positron slows to speeds similar to those of electrons in the material, the positron will annihilate an electron, releasing two gamma photons of 511 keV in the process. Those two gamma photons will be traveling in (approximately) opposite direction. The gamma radiation from positron annihilation consists of high energy photons, and

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4116-527: Is stripped (or "knocked out") from an electron shell of the atom, which leaves the atom with a net positive charge. Because living cells and, more importantly, the DNA in those cells can be damaged by this ionization, exposure to ionizing radiation increases the risk of cancer . Thus "ionizing radiation" is somewhat artificially separated from particle radiation and electromagnetic radiation, simply due to its great potential for biological damage. While an individual cell

4214-414: Is technically not ionizing. The highest frequencies of ultraviolet light, as well as all X-rays and gamma-rays are ionizing. The occurrence of ionization depends on the energy of the individual particles or waves, and not on their number. An intense flood of particles or waves will not cause ionization if these particles or waves do not carry enough energy to be ionizing, unless they raise the temperature of

4312-407: Is the heat emitted by an operating incandescent light bulb. Thermal radiation is generated when energy from the movement of charged particles within atoms is converted to electromagnetic radiation. As noted above, even low-frequency thermal radiation may cause temperature-ionization whenever it deposits sufficient thermal energy to raise temperatures to a high enough level. Common examples of this are

4410-696: Is the range of all possible electromagnetic radiation frequencies. The electromagnetic spectrum (usually just spectrum) of an object is the characteristic distribution of electromagnetic radiation emitted by, or absorbed by, that particular object. The non-ionizing portion of electromagnetic radiation consists of electromagnetic waves that (as individual quanta or particles, see photon ) are not energetic enough to detach electrons from atoms or molecules and hence cause their ionization. These include radio waves, microwaves, infrared, and (sometimes) visible light. The lower frequencies of ultraviolet light may cause chemical changes and molecular damage similar to ionization, but

4508-557: The Caesarean section . Before the 1880s mortality rates in lying-hospitals would reach unacceptably high levels and became an area of public concern. Much of these maternal deaths were due to puerperal fever , then known as childbed fever. In the 1800s Ignaz Semmelweis noticed that women giving birth at home had a much lower incidence of childbed fever than those giving birth by physicians in lying-hospitals. His investigation discovered that washing hands with an antiseptic solution before

4606-534: The Sun and detected the infrared (beyond the red part of the spectrum), through an increase in the temperature recorded by a thermometer . In 1801, the German physicist Johann Wilhelm Ritter made the discovery of ultraviolet by noting that the rays from a prism darkened silver chloride preparations more quickly than violet light. Ritter's experiments were an early precursor to what would become photography. Ritter noted that

4704-537: The female reproductive system and sexual practice can be traced back to Ancient Egypt and Ancient Greece. Soranus of Ephesus sometimes is called the most important figure in ancient gynecology. Living in the late first century AD and early second century, he studied anatomy and had opinions and techniques on abortion, contraception – most notably coitus interruptus  – and birth complications. After his death, techniques and works of gynecology declined; very little of his works were recorded and survived to

4802-403: The 18th century. The role of a physician was exclusively held by men who went to university, an overly male institution, who would theorize anatomy and the process of reproduction based on theological teaching and philosophy. Many beliefs about the female body and menstruation in the 17th and 18th centuries were inaccurate; clearly resulting from the lack of literature about the practice. Many of

4900-623: The American medical field at the end of the nineteenth century through the development of such procedures as the ovariotomy. These procedures then were shared with European surgeons who replicated the surgeries. This was a period when antiseptic, aseptic or anaesthetic measures were just being introduced to surgical and observational procedures and without these procedures surgeries were dangerous and often fatal. Following are two surgeons noted for their contributions to these fields include Ephraim McDowell and J. Marion Sims . Ephraim McDowell developed

4998-644: The Earth from outer space were finally definitively recognized and proven to exist in 1912, as the scientist Victor Hess carried an electrometer to various altitudes in a free balloon flight. The nature of these radiations was only gradually understood in later years. The Neutron and neutron radiation were discovered by James Chadwick in 1932. A number of other high energy particulate radiations such as positrons , muons , and pions were discovered by cloud chamber examination of cosmic ray reactions shortly thereafter, and others types of particle radiation were produced artificially in particle accelerators , through

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5096-576: The UV rays were capable of causing chemical reactions. The first radio waves detected were not from a natural source, but were produced deliberately and artificially by the German scientist Heinrich Hertz in 1887, using electrical circuits calculated to produce oscillations in the radio frequency range, following formulas suggested by the equations of James Clerk Maxwell . Wilhelm Röntgen discovered and named X-rays . While experimenting with high voltages applied to an evacuated tube on 8 November 1895, he noticed

5194-422: The absolute temperature of that body. The radiation emitted covers the entire electromagnetic spectrum and the intensity of the radiation (power/unit-area) at a given frequency is described by Planck's law of radiation. For a given temperature of a black-body there is a particular frequency at which the radiation emitted is at its maximum intensity. That maximum radiation frequency moves toward higher frequencies as

5292-466: The absorption of X-rays. X-ray machines are specifically designed to take advantage of the absorption difference between bone and soft tissue, allowing physicians to examine structure in the human body. X-rays are also totally absorbed by the thickness of the earth's atmosphere, resulting in the prevention of the X-ray output of the sun, smaller in quantity than that of UV but nonetheless powerful, from reaching

5390-423: The beginning of the century. But obstetrics was underdeveloped compared to other medical specialities. Many male physicians would deliver children but very few would have referred to themselves as obstetricians. The end of the 19th century did mark a significant accomplishment in the profession with the advancements in asepsis and anaesthesia , which paved the way for the mainstream introduction and later success of

5488-555: The biological proclivities of the radioactive iodine fission product, iodine-131 . However, calculating the exact risk and chance of cancer forming in cells caused by ionizing radiation is still not well understood, and currently estimates are loosely determined by population-based data from the atomic bombings of Hiroshima and Nagasaki and from follow-up of reactor accidents, such as the Chernobyl disaster . The International Commission on Radiological Protection states that "The Commission

5586-539: The birth of a child would be in the sitting position, usually when performed on the side of a bed to support the mother. Men were introduced into the field of obstetrics in the nineteenth century and resulted in a change of the focus of this profession. Gynaecology directly resulted as a new and separate field of study from obstetrics and focused on the curing of illness and indispositions of female sexual organs. This had some relevance to some conditions as menopause, uterine and cervical problems, and childbirth could leave

5684-553: The bonds which are sensed as heat . Radio wavelengths and below generally are not regarded as harmful to biological systems. These are not sharp delineations of the energies; there is some overlap in the effects of specific frequencies . The word "radiation" arises from the phenomenon of waves radiating (i.e., traveling outward in all directions) from a source. This aspect leads to a system of measurements and physical units that apply to all types of radiation. Because such radiation expands as it passes through space, and as its energy

5782-457: The energy away as radio waves; these are mostly termed interference. Different frequencies of radio waves have different propagation characteristics in the Earth's atmosphere; long waves may bend at the rate of the curvature of the Earth and may cover a part of the Earth very consistently, shorter waves travel around the world by multiple reflections off the ionosphere and the Earth. Much shorter wavelengths bend or reflect very little and travel along

5880-545: The energy of such waves by passing through, on the average, 500 ft (150 m). Alpha particles are helium-4 nuclei (two protons and two neutrons). They interact with matter strongly due to their charges and combined mass, and at their usual velocities only penetrate a few centimetres of air, or a few millimetres of low density material (such as the thin mica material which is specially placed in some Geiger counter tubes to allow alpha particles in). This means that alpha particles from ordinary alpha decay do not penetrate

5978-399: The entire super high frequency band (3 to 30 GHz, or 10 to 1 cm) at minimum, with RF engineering often putting the lower boundary at 1 GHz (30 cm), and the upper around 100 GHz (3 mm). Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. Like all other electromagnetic waves, they travel at

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6076-440: The eventual need for midwives to become certified. Many European countries by the late 19th century were monitoring the training of midwives and issued certification based on competency. Midwives were no longer uneducated in the formal sense. As midwifery began to develop, so did the profession of obstetrics near the end of the century. Childbirth was no longer unjustifiably despised by the medical community as it once had been at

6174-608: The foetus. No effects of magnetic resonance imaging (MRI) on the foetus have been demonstrated, but this technique is too expensive for routine observation. Instead, obstetric ultrasonography is the imaging method of choice in the first trimester and throughout the pregnancy, because it emits no radiation , is portable, and allows for realtime imaging. The safety of frequent ultrasound scanning has not been confirmed. Despite this, increasing numbers of women are choosing to have additional scans for no medical purpose, such as gender scans, 3D and 4D scans. A normal gestation would reveal

6272-409: The ionization (plasma) seen in common flames, and the molecular changes caused by the " browning " during food-cooking, which is a chemical process that begins with a large component of ionization. Black-body radiation is an idealized spectrum of radiation emitted by a body that is at a uniform temperature. The shape of the spectrum and the total amount of energy emitted by the body is a function of

6370-406: The ionizing radiation is a radioactive material or a nuclear process such as fission or fusion , there is particle radiation to consider. Particle radiation is subatomic particles accelerated to relativistic speeds by nuclear reactions. Because of their momenta , they are quite capable of knocking out electrons and ionizing materials, but since most have an electrical charge, they do not have

6468-569: The late 18th century when gynecology and obstetrics reemerged as a medical specialism. The 18th century marked the beginning of many advances in European midwifery , based on better knowledge of the physiology of pregnancy and labour. By the end of the century, medical professionals began to understand the anatomy of the uterus and the physiological changes that take place during labour. The introduction of forceps in childbirth also took place at this time. All these medical advances in obstetrics were

6566-401: The late 1980s. Obstetric ultrasonography is routinely used for dating the gestational age of a pregnancy from the size of the fetus , determine the number of fetuses and placentae , evaluate for an ectopic pregnancy and first trimester bleeding, the most accurate dating being in first trimester before the growth of the foetus has been significantly influenced by other factors. Ultrasound

6664-522: The line of sight. Very low frequency (VLF) refers to a frequency range of 30 Hz to 3 kHz which corresponds to wavelengths of 100 000 to 10 000  m respectively. Since there is not much bandwidth in this range of the radio spectrum, only the very simplest signals can be transmitted, such as for radio navigation. Also known as the myriametre band or myriametre wave as the wavelengths range from 100 km to 10 km (an obsolete metric unit equal to 10 km). Extremely low frequency (ELF)

6762-425: The material is of high or low density. However, as is the case with X-rays, materials with a high atomic number such as lead or depleted uranium add a modest (typically 20% to 30%) amount of stopping power over an equal mass of less dense and lower atomic weight materials (such as water or concrete). The atmosphere absorbs all gamma rays approaching Earth from space. Even air is capable of absorbing gamma rays, halving

6860-404: The most common isotopes of both types atoms present (hydrogen and oxygen) capture neutrons and become heavier but remain stable forms of those atoms. Only the absorption of more than one neutron, a statistically rare occurrence, can activate a hydrogen atom, while oxygen requires two additional absorptions. Thus water is only very weakly capable of activation. The sodium in salt (as in sea water), on

6958-406: The mother in need of extensive surgery to repair tissue. But, there was also a large blame of the uterus for completely unrelated conditions. This led to many social consequences of the nineteenth century. Radiation In physics , radiation is the emission or transmission of energy in the form of waves or particles through space or a material medium. This includes: Radiation

7056-757: The national standard in the United States, is rapidly evolving away from the AFP- quad screen , done typically in the second trimester at 16–18 weeks. The newer integrated screen (formerly called F.A.S.T.E.R for First And Second Trimester Early Results) can be done at 10 plus weeks to 13 plus weeks with an ultrasound of the fetal neck (thicker nuchal skin correlates with higher risk of Down syndrome being present) and two chemicals (analytes), pregnancy-associated plasma protein A and human chorionic gonadotropin (pregnancy hormone level itself ). It gives an accurate risk profile very early. A second blood screen at 15 to 20 weeks refines

7154-448: The neutrons stops almost immediately in the reactor when it goes non-critical. Neutrons can make other objects, or material, radioactive. This process, called neutron activation , is the primary method used to produce radioactive sources for use in medical, academic, and industrial applications. Even comparatively low speed thermal neutrons cause neutron activation (in fact, they cause it more efficiently). Neutrons do not ionize atoms in

7252-463: The obstetrician carries out the following tasks: The main emergencies include: The World Health Organization makes a distinction between the use of postpartum care when it concerns the care of the mother after giving birth, and postnatal care when the care of the newborn is concerned. Postpartum care is provided to the mother following childbirth. A woman in the Western world who gives birth in

7350-413: The other hand, need only absorb a single neutron to become Na-24, a very intense source of beta decay, with half-life of 15 hours. In addition, high-energy (high-speed) neutrons have the ability to directly ionize atoms. One mechanism by which high energy neutrons ionize atoms is to strike the nucleus of an atom and knock the atom out of a molecule, leaving one or more electrons behind as the chemical bond

7448-497: The outer layers of dead skin cells and cause no damage to the live tissues below. Some very high energy alpha particles compose about 10% of cosmic rays , and these are capable of penetrating the body and even thin metal plates. However, they are of danger only to astronauts, since they are deflected by the Earth's magnetic field and then stopped by its atmosphere. Alpha radiation is dangerous when alpha-emitting radioisotopes are ingested or inhaled (breathed or swallowed). This brings

7546-614: The penetrating power of ionizing radiation. The exception is neutron particles; see below. There are several different kinds of these particles, but the majority are alpha particles , beta particles , neutrons , and protons . Roughly speaking, photons and particles with energies above about 10 electron volts (eV) are ionizing (some authorities use 33 eV, the ionization energy for water). Particle radiation from radioactive material or cosmic rays almost invariably carries enough energy to be ionizing. Most ionizing radiation originates from radioactive materials and space (cosmic rays), and as such

7644-514: The radioisotope close enough to sensitive live tissue for the alpha radiation to damage cells. Per unit of energy, alpha particles are at least 20 times more effective at cell-damage as gamma rays and X-rays. See relative biological effectiveness for a discussion of this. Examples of highly poisonous alpha-emitters are all isotopes of radium , radon , and polonium , due to the amount of decay that occur in these short half-life materials. Beta-minus (β ) radiation consists of an energetic electron. It

7742-521: The remainder consisting of helions (alpha particles). A few completely ionized nuclei of heavier elements are present. The origin of these galactic cosmic rays is not yet well understood, but they seem to be remnants of supernovae and especially gamma-ray bursts (GRB), which feature magnetic fields capable of the huge accelerations measured from these particles. They may also be generated by quasars , which are galaxy-wide jet phenomena similar to GRBs but known for their much larger size, and which seem to be

7840-477: The risk more accurately. The cost is higher than an "AFP-quad" screen due to the ultrasound and second blood test, but it is quoted to have a 93% pick up rate as opposed to 88% for the standard AFP/QS. This is an evolving standard of care in the United States. Most doctors do a sugar load in a drink form of 50 grams of glucose in cola, lime or orange and draw blood an hour later (plus or minus 5 minutes). The standard modified criteria have been lowered to 135 since

7938-482: The same way that charged particles such as protons and electrons do (by the excitation of an electron), because neutrons have no charge. It is through their absorption by nuclei which then become unstable that they cause ionization. Hence, neutrons are said to be "indirectly ionizing". Even neutrons without significant kinetic energy are indirectly ionizing, and are thus a significant radiation hazard. Not all materials are capable of neutron activation; in water, for example,

8036-434: The secondary cosmic rays that are produced after primary cosmic rays interact with Earth's atmosphere . Gamma rays, X-rays, and the higher energy range of ultraviolet light constitute the ionizing part of the electromagnetic spectrum . The word "ionize" refers to the breaking of one or more electrons away from an atom, an action that requires the relatively high energies that these electromagnetic waves supply. Further down

8134-432: The spectrum, the non-ionizing lower energies of the lower ultraviolet spectrum cannot ionize atoms, but can disrupt the inter-atomic bonds that form molecules, thereby breaking down molecules rather than atoms; a good example of this is sunburn caused by long- wavelength solar ultraviolet. The waves of longer wavelength than UV in visible light, infrared, and microwave frequencies cannot break bonds but can cause vibrations in

8232-404: The speed of light. Naturally occurring radio waves are made by lightning, or by certain astronomical objects. Artificially generated radio waves are used for fixed and mobile radio communication, broadcasting, radar and other navigation systems, satellite communication, computer networks and innumerable other applications. In addition, almost any wire carrying alternating current will radiate some of

8330-440: The surface. Gamma (γ) radiation consists of photons with a wavelength less than 3 × 10  m (greater than 10  Hz and 41.4 keV). Gamma radiation emission is a nuclear process that occurs to rid an unstable nucleus of excess energy after most nuclear reactions. Both alpha and beta particles have an electric charge and mass, and thus are quite likely to interact with other atoms in their path. Gamma radiation, however,

8428-406: The temperature of its radiating surface. It is responsible for the color of stars , which vary from infrared through red ( 2500 K ), to yellow ( 5800 K ), to white and to blue-white ( 15 000  K ) as the peak radiance passes through those points in the visible spectrum. When the peak is below the visible spectrum the body is black, while when it is above the body is blue-white, since all

8526-421: The temperature of the body increases. The frequency at which the black-body radiation is at maximum is given by Wien's displacement law and is a function of the body's absolute temperature. A black-body is one that emits at any temperature the maximum possible amount of radiation at any given wavelength. A black-body will also absorb the maximum possible incident radiation at any given wavelength. A black-body with

8624-454: The theories of what caused menstruation prevailed from Hippocratic philosophy. Midwives , meaning "with woman", were those who assisted in the birth and care of both born and unborn children, a position historically held mainly by women. During the birth of a child, men were rarely present. Women from the neighbourhood or family would join in on the process of birth and assist in many different ways. The one position where men would help with

8722-437: The ultraviolet spectrum some of the dangers of ionizing radiation in biological systems without actual ionization occurring. In contrast, visible light and longer-wavelength electromagnetic radiation, such as infrared, microwaves, and radio waves, consists of photons with too little energy to cause damaging molecular excitation, and thus this radiation is far less hazardous per unit of energy. X-rays are electromagnetic waves with

8820-444: The ultraviolet spectrum that does reach the ground is non-ionizing, but is still biologically hazardous due to the ability of single photons of this energy to cause electronic excitation in biological molecules, and thus damage them by means of unwanted reactions. An example is the formation of pyrimidine dimers in DNA, which begins at wavelengths below 365 nm (3.4 eV), which is well below ionization energy. This property gives

8918-457: The visible colors are represented from blue decreasing to red. Electromagnetic radiation of wavelengths other than visible light were discovered in the early 19th century. The discovery of infrared radiation is ascribed to William Herschel , the astronomer . Herschel published his results in 1800 before the Royal Society of London . Herschel, like Ritter, used a prism to refract light from

9016-411: Was a way for these men to demonstrate their knowledge. Many midwives of the time bitterly opposed the involvement of men in childbirth. Some male practitioners also opposed the involvement of medical men like themselves in midwifery and even went as far as to say that male-midwives only undertook midwifery solely for perverse erotic satisfaction. The accoucheurs argued that their involvement in midwifery

9114-587: Was both successfully and unsuccessfully being performed. Pennsylvanian surgeons the Attlee brothers made this procedure very routine for a total of 465 surgeries – John Attlee performed 64 successfully of 78 while his brother William reported 387 – between the years of 1843 and 1883. By the middle of the nineteenth century this procedure was successfully performed in Europe by English surgeons Sir Spencer Wells and Charles Clay as well as French surgeons Eugène Koeberlé , Auguste Nélaton and Jules Péan . J. Marion Sims

9212-479: Was entirely ignored. This made it nearly impossible to pursue an education in midwifery and also have the recognition of being a doctor or surgeon. Obstetrics was pushed to the side. By the late 19th century, the foundation of modern-day obstetrics and midwifery began developing. Delivery of babies by doctors became popular and readily accepted, but midwives continued to play a role in childbirth. Midwifery also changed during this era due to increased regulation and

9310-705: Was the radiation that had been first detected by Becquerel from uranium salts. In 1900, the French scientist Paul Villard discovered a third neutrally charged and especially penetrating type of radiation from radium, and after he described it, Rutherford realized it must be yet a third type of radiation, which in 1903 Rutherford named gamma rays . Henri Becquerel himself proved that beta rays are fast electrons, while Rutherford and Thomas Royds proved in 1909 that alpha particles are ionized helium. Rutherford and Edward Andrade proved in 1914 that gamma rays are like X-rays, but with shorter wavelengths. Cosmic ray radiations striking

9408-467: Was the rejection of obstetrics by the medical community. The 19th century marked an era of medical reform in Europe and increased regulation over the profession. Major European institutions such as The College of Physicians and Surgeons considered delivering babies ungentlemanly work and refused to have anything to do with childbirth as a whole. Even when Medical Act 1858 was introduced, which stated that medical students could qualify as doctors, midwifery

9506-463: Was the surgeon responsible for being the first treating a vesicovaginal fistula – a condition linked to many caused mainly by prolonged pressing of the foetus against the pelvis or other causes such as rape, hysterectomy, or other operations – and also having been doctor to many European royals and the 20th President of the United States James A. Garfield after he had been shot. Sims does have

9604-400: Was to improve the process of childbirth. These men also believed that obstetrics would forge ahead and continue to strengthen. 18th-century physicians expected that obstetrics would continue to grow, but the opposite happened. Obstetrics entered a stage of stagnation in the 19th century, which lasted until about the 1880s. The central explanation for the lack of advancement during this time

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