Győr

Coordinates: 47°41′03″N 17°38′04″E / 47.68417°N 17.63444°E / 47.68417; 17.63444

Győr (Hungarian pronunciation: [ˈɟøːr]; German: Raab, Slovak: Ráb, Turkish: Yanıkkale, names in other languages) is the most important city of northwest Hungary, the capital of Győr-Moson-Sopron County and Western Transdanubia region, and—halfway between Budapest and Vienna—situated on one of the important roads of Central Europe. The city is the sixth-largest in Hungary, and one of the seven main regional centres of the country.

History

The area along the Danube River has been inhabited by varying cultures since ancient times. The first large settlement dates back to the 5th century BCE; the inhabitants were Celts. They called the town Arrabona, a name that was used for eight centuries; its shortened form is still used as the German (Raab) and Slovak (Ráb) names of the city.

Roman merchants moved to Arrabona during the 1st century BCE. Around 10 CE, the Roman army occupied the northern part of Western Hungary, which they called Pannonia. Although the Roman Empire abandoned the area in the 4th century due to constant attacks by the tribes living to the east, the town remained inhabited.

Mazda Wankel engine

The Mazda Wankel engines (a type of rotary combustion engine) comprise a family of car engines derived from experiments in the early 1960s by Felix Wankel, a German engineer. Over the years, displacement has been increased and turbocharging has been added.

Wankel engines can be classified by their geometric size in terms of radius (rotor center to tip distance, also the median stator radius) and depth (rotor thickness), and offset (crank throw, eccentricity, also 1/4 the difference between stator's major and minor axes). These metrics function similarly to the bore and stroke measurements of a piston engine. Displacement is 3√3radius·offset·depth, multiplied with the number of rotors (note that this only counts a single face of each rotor as the entire rotor's displacement). Nearly all Mazda production Wankel engines share a single rotor radius, 105 mm (4.1 in), with a 15 mm (0.6 in) crankshaft offset. The only engine to diverge from this formula was the rare 13A, which used a 120 mm (4.7 in) rotor radius and 17.5 mm (0.7 in) crankshaft offset.

Tetrabromomethane

Tetrabromomethane, CBr₄, also known as carbon tetrabromide, is a carbon bromide. Both names are acceptable under IUPAC nomenclature.

Physical properties

Tetrabromomethane has two polymorphs: crystalline II or β below 46.9 °C (320.0 K) and crystalline I or α above 46.9 °C. Monoclinic polymorph has space group C2/c with lattice constants: a = 20.9, b = 12.1, c = 21.2 (.10⁻¹ nm), β = 110.5°.Bond energy of C-Br is 235 kJ.mol⁻¹.

Due to its symmetrically substituted tetrahedral structure, its dipole moment is 0 Debye. Critical temperature is 439 °C (712 K) and critical pressure is 4.26 MPa.

Plastic crystallinity

The high temperature α phase is known as a plastic crystal phase. Roughly speaking, the CBr₄ are situated on the corners of the cubic unit cell as well as on the centers of its faces in an fcc arrangement. It was thought in the past that the molecules could rotate more or less freely (a 'rotor phase'), so that on a time average they would look like spheres. Recent work has shown, however, that the molecules are restricted to only 6 possible orientations (Frenkel disorder). Moreover, they cannot take these orientations entirely independently from each other because in some cases the bromine atoms of neighboring molecules would point at each other leading to impossibly short distances. This rules out certain orientational combinations when two neighbor molecules are considered. Even for the remaining combinations displacive changes occur that better accommodate neighbor to neighbor distances. The combination of censored Frenkel disorder and displacive disorder implies a considerable amount of disorder inside the crystal which leads to highly structured sheets of diffuse scattered intensity in X-ray diffraction. In fact, it is the structure in the diffuse intensity that provides the information about the details of the structure.

Top

A top is a toy designed to be spun rapidly on the ground, the motion of which causes it to remain precisely balanced on its tip because of inertia. Such toys have existed since antiquity. Traditionally tops were constructed of wood, sometimes with an iron tip, and would be set in motion by aid of a string or rope coiled around its axis which, when pulled quickly, caused a rapid unwinding that would set the top in motion. Today they are often built of plastic, and modern materials and manufacturing processes allow tops to be constructed with such precise balance that they can be set in motion by a simple twist of the fingers and twirl of the wrist without need for string or rope.

Characteristics

The motion of a top is produced in the most simple forms by twirling the stem using the fingers. More sophisticated tops are spun by holding the axis firmly while pulling a string or twisting a stick or pushing an auger. In the kinds with an auger, an internal weight rotates, producing an overall circular motion. Some tops can be thrown, while firmly grasping a string that had been tightly wound around the stem, and the centrifugal force generated by the unwinding motion of the string will set them spinning upon touching ground.

Top (clothing)

A top is clothing that covers at least the chest, but which usually covers most of the upper human body between the neck and the waistline. The bottom of tops can be as short as mid-torso, or as long as mid-thigh. Men's tops are generally paired with pants, and women's with pants or skirts. Common types of tops are t-shirts, blouses and shirts.

Design

The neckline is the highest line of the top, and may be as high as a head-covering hood, or as low as the waistline or bottom hem of the top. A top may be worn loose or tight around the bust or waist, and may have sleeves or shoulder straps, spaghetti straps (noodle straps), or may be strapless. The back may be covered or bare. Tops may have straps around the waist or neck, or over the shoulders.

Types

Neck styles

See also

References

External links

Category of topological spaces

In mathematics, the category of topological spaces, often denoted Top, is the category whose objects are topological spaces and whose morphisms are continuous maps or some other variant; for example, objects are often assumed to be compactly generated. This is a category because the composition of two continuous maps is again continuous. The study of Top and of properties of topological spaces using the techniques of category theory is known as categorical topology.

N.B. Some authors use the name Top for the category with topological manifolds as objects and continuous maps as morphisms.

As a concrete category

Like many categories, the category Top is a concrete category (also known as a construct), meaning its objects are sets with additional structure (i.e. topologies) and its morphisms are functions preserving this structure. There is a natural forgetful functor

to the category of sets which assigns to each topological space the underlying set and to each continuous map the underlying function.

Hip hop music

Hip hop music, also called hip-hop or rap music, is a music genre formed in the United States in the 1970s that consists of a stylized rhythmic music that commonly accompanies rapping, a rhythmic and rhyming speech that is chanted. It developed as part of hip hop culture, a subculture defined by four key stylistic elements: MCing/rapping, DJing/scratching, break dancing, and graffiti writing. Other elements include sampling (or synthesis), and beatboxing.

While often used to refer to rapping, "hip hop" more properly denotes the practice of the entire subculture. The term hip hop music is sometimes used synonymously with the term rap music, though rapping is not a required component of hip hop music; the genre may also incorporate other elements of hip hop culture, including DJing, turntablism, and scratching, beatboxing, and instrumental tracks.