A tenement is a type of building shared by multiple dwellings with flats or apartments on each floor and with shared entrance stairway access. These are common in Scotland. In the medieval Old Town, tenements were developed with each apartment treated as a separate house, built on top of each other. Over hundreds of years customary law of tenements grew to allocate responsibilities for maintenance, as first formally discussed in Stair's 1681 writings on Scots law. Tenements with one or two room flats provided popular rented accommodation for workers, but in some inner-city areas overcrowding and maintenance problems led to slums which have been cleared and redeveloped. In more affluent areas tenement flats form spacious owned houses, some with up to six bedrooms, which continue to be desirable properties. In the United States, the term tenement meant a large building with multiple small spaces to rent; as cities grew in the nineteenth century, there was increasing separation between poor. With rapid urban growth and immigration, overcrowded houses with poor sanitation gave tenements a reputation as slums.

The expression “tenement house” was used to designate a building subdivided to provide cheap rental accommodation: this was subdivision of a large house, from the 1850s purpose-built tenements of up to six storeys held several households on each floor. Various names were introduced for better dwellings, modern apartments predominated in American urban living. In parts of England Devon and Cornwall, the word refers to an outshot, or additional projecting part at the back of a terraced house with its own roof; the term tenement referred to tenancy and therefore to any rented accommodation. The New York State legislature defined it in the Tenement House Act of 1867 in terms of rental occupancy by multiple households, as Any house, building, or portion thereof, rented, let, or hired out to be occupied or is occupied, as the home or residence of more than three families living independently of one another and doing their own cooking upon the premises, or by more than two families upon a floor, so living and cooking and having a common right in the halls, yards, water-closets, or privies, or some of them.

In Scotland, it continues to be the most common word for a multiple-occupancy building, but elsewhere it is used as a pejorative in contrast to apartment building or block of flats. Tenement houses were either adapted or built for the working class as cities industrialized, came to be contrasted with middle-class apartment houses, which started to become fashionable in the 19th century. Late-19th-century social reformers in the US were hostile to both tenements and apartment houses; as the United States industrialized during the 19th century and workers from the countryside were housed in former middle-class houses and other buildings, such as warehouses, which were bought up and divided into small dwellings. Beginning as early as the 1830s in New York City's Lower East Side or the 1820s on Mott Street, three- and four-story buildings were converted into "railroad flats," so called because the rooms were linked together like the cars of a train, with windowless internal rooms; the adapted buildings were known as "rookeries," and these were a particular concern, as they were prone to collapse and fire.

Mulberry Bend and Five Points were the sites of notorious rookeries that the city worked for decades to clear. In both rookeries and purpose-built tenements, communal water taps and water closets were squeezed into the small open spaces between buildings. In parts of the Lower East Side, buildings were older and had courtyards occupied by machine shops and other businesses; such tenements were prevalent in New York, where in 1865 a report stated that 500,000 people lived in unhealthy tenements, whereas in Boston in 1845, less than a quarter of workers were housed in tenements. One reason New York had so many tenements was the large numbers of immigrants. Prior to 1867, tenements covered more than 90 percent of the lot, were five or six stories high, had 18 rooms per floor, of which only two received direct sunlight. Yards were a few feet wide and filled with privies. Interior rooms were unventilated. Early in the 19th century, many of the poor were housed in cellars, which became less sanitary after the Croton Aqueduct brought running water to wealthier New Yorkers: the reduction in well use caused the water table to rise, the cellar dwellings flooded.

Early housing reformers urged the construction of tenements to replace cellars, beginning in 1859 the number of people living in cellars began to decline. The Tenement House Act of 1866, the state legislature's first comprehensive legislation on housing conditions, prohibited cellar apartments unless the ceiling was 1 foot above street level; this was amended by the Tenement House Act of 1879, known as the Old Law, which required lot coverage of no more than 65 percent. As of 1869, New York State law defined a “tenement house” as “any house or building, or portion thereof, rented, leased let or hired out, to be occupied, or is occupied as the home or residence of three families or more

Quasi-periodic oscillation

In X-ray astronomy, quasi-periodic oscillation is the manner in which the X-ray light from an astronomical object flickers about certain frequencies. In these situations, the X-rays are emitted near the inner edge of an accretion disk in which gas swirls onto a compact object such as a white dwarf, neutron star, or black hole; the QPO phenomenon promises to help astronomers understand the innermost regions of accretion disks and the masses and spin periods of white dwarfs, neutron stars, black holes. QPOs could help test Albert Einstein's theory of general relativity which makes predictions that differ most from those of Newtonian gravity when the gravitational force is strongest or when rotation is fastest However, the various explanations of QPOs remain controversial and the conclusions reached from their study remain provisional. A QPO is identified by performing a power spectrum of the time series of the X-rays. A constant level of white noise is expected from the random variation of sampling the object's light.

Systems that show QPOs sometimes show nonperiodic noise that appears as a continuous curve in the power spectrum. A periodic pulsation appears in the power spectrum as a peak of power at one frequency. A QPO, on the other hand, appears as a broader peak, sometimes with a Lorentzian shape. What sort of variation with time could cause a QPO? For example, the power spectrum of an oscillating shot appears as a continuum of noise together with a QPO. An oscillating shot is a sinusoidal variation that starts and decays exponentially. A scenario in which oscillating shots cause the observed QPOs could involve "blobs" of gas in orbit around a rotating, weakly magnetized neutron star; each time a blob comes near more gas accretes and the X-rays increase. At the same time, the blob's mass decreases. Power spectra are formed from several time intervals and added together before the QPO can be seen to be statistically significant. QPOs were first identified in white dwarf systems and in neutron star systems.

At first the neutron star systems found to have QPOs were of a class not known to have pulsations. The spin periods of these neutron stars were unknown as a result; these neutron stars are thought to have low magnetic fields so the gas does not fall onto their magnetic poles, as in accreting pulsars. Because their magnetic fields are so low, the accretion disk can get close to the neutron star before being disrupted by the magnetic field; the spectral variability of these neutron stars was seen to correspond to changes in the QPOs. Typical QPO frequencies were found to be between 60 hertz; the fastest oscillations were found in a spectral state called the Horizontal Branch, were thought to be a result of the combined rotation of the matter in the disk and the rotation of the collapsed star. During the Normal Branch and Flaring Branch, the star was thought to approach its Eddington luminosity at which the force of the radiation could repel the accreting gas; this could give rise to a different kind of oscillation.

Observations starting in 1996 with the Rossi X-ray Timing Explorer could detect faster variability, it was found that neutron stars and black holes emit X-rays that have QPOs with frequencies up to 1000 hertz or so. "twin peak" QPOs were found in which two oscillations of the same power appeared at high amplitudes. These higher frequency QPOs may show behavior related to that of the lower frequency QPOs. QPOs can be used to determine the mass of black holes; the technique uses a relationship between black holes and the inner part of their surrounding disks, where gas spirals inward before reaching the event horizon. The hot gas piles up near the black hole and radiates a torrent of X-rays, with an intensity that varies in a pattern that repeats itself over a nearly regular interval; this signal is the QPO. Astronomers have long suspected; the congestion zone lies close in for small black holes, so the QPO clock ticks quickly. As black holes increase in mass, the congestion zone is pushed farther out, so the QPO clock ticks slower and slower.

Broad iron K line Quasiperiodicity

Dedications (Toshiko Akiyoshi Trio album)

The jazz trio album Dedications was recorded by pianist Toshiko Akiyoshi in Los Angeles in July 1976 and was released by Discomate Records in Japan. This recording is not to be confused with the 1977 Inner City Records release of the same name, released by Discomate in Japan, but under the title Dedications II. LP side A "I Let a Song Go Out of My Heart" – 4:21 "Miss Blue Eyes" – 5:45 "Django" – 6:05 "Rio" – 3:53LP side B "Wind" – 6:01 "Reets and I" – 4:42 "Don't Be Afraid, The Clown's Afraid Too" – 5:34 "Let The Tape Roll" – 3:09 Toshiko Akiyoshi – piano Jimmie Smithdrums Gene Chericobass Discomate DSP-5001 Alfa Records ALCR-161