Backë

Backë is a village in the former municipality of Potom in Berat County, Albania. At the 2015 local government reform it became part of the municipality Skrapar.

References

Human back

The human back is the large posterior area of the human body, rising from the top of the buttocks to the back of the neck and the shoulders. It is the surface opposite to the chest, its height being defined by the vertebral column (commonly referred to as the spine or backbone) and its breadth being supported by the ribcage and shoulders. The spinal canal runs through the spine and provides nerves to the rest of the body.

Structure

The central feature of the human back is the vertebral column, specifically the length from the top of the thoracic vertebrae to the bottom of the lumbar vertebrae, which houses the spinal cord in its spinal canal, and which generally has some curvature that gives shape to the back. The ribcage extends from the spine at the top of the back (with the top of the ribcage corresponding to the T1 vertebra), more than halfway down the length of the back, leaving an area with less protection between the bottom of the ribcage and the hips. The width of the back at the top is defined by the scapula, the broad, flat bones of the shoulders.

Defender (association football)

In the sport of association football, a defender is an outfield player whose primary role is to prevent the opposing team from scoring goals.

There are four types of defenders: centre-back, sweeper, full-back, and wing-back. The centre-back and full-back positions are essential in most modern formations. The sweeper and wing-back roles are more specialised for certain formations.

Centre-back

A centre-back (also known as a central defender or centre-half) defends in the area directly in front of the goal, and tries to prevent opposing players, particularly centre-forwards, from scoring. Centre-backs accomplish this by blocking shots, tackling, intercepting passes, contesting headers and marking forwards to discourage the opposing team from passing to them.

With the ball, centre-backs are generally expected to make short and simple passes to their teammates, or to kick unaimed long balls down the field. For example, a clearance is a long unaimed kick intended to move the ball as far as possible from the defender's goal.

Catalysis

Catalysis (/kəˈtælᵻsᵻs/) is the increase in the rate of a chemical reaction due to the participation of an additional substance called a catalyst (/ˈkætəlᵻst/). With a catalyst, reactions occur faster and require less activation energy. Because catalysts are not consumed in the catalyzed reaction, they can continue to catalyze the reaction of further quantities of reactant. Often only tiny amounts are required.

Technical perspective

In the presence of a catalyst, less free energy is required to reach the transition state, but the total free energy from reactants to products does not change. A catalyst may participate in multiple chemical transformations. The effect of a catalyst may vary due to the presence of other substances known as inhibitors or poisons (which reduce the catalytic activity) or promoters (which increase the activity). The opposite of a catalyst, a substance that reduces the rate of a reaction, is an inhibitor.

Catalyzed reactions have a lower activation energy (rate-limiting free energy of activation) than the corresponding uncatalyzed reaction, resulting in a higher reaction rate at the same temperature and for the same reactant concentrations. However, the detailed mechanics of catalysis is complex. Catalysts may affect the reaction environment favorably, or bind to the reagents to polarize bonds, e.g. acid catalysts for reactions of carbonyl compounds, or form specific intermediates that are not produced naturally, such as osmate esters in osmium tetroxide-catalyzed dihydroxylation of alkenes, or cause dissociation of reagents to reactive forms, such as chemisorbed hydrogen in catalytic hydrogenation.

Catalyst (disambiguation)

A catalyst is a substance which increases the rate of a chemical reaction.

Catalyst may also refer to:

Buildings

Economics and finance

Events

Media and entertainment

Games

Literature and publications

Catalyst (TV program)

Catalyst is the ABC's primary science journalism television series and the only science show on primetime television in Australia. Launched in 2001, it replaced Quantum, which had ceased the previous year. Catalyst is regularly broadcast on ABC 1 at 8:00 pm on Tuesdays and at 11:30 am Saturdays. Also repeated on ABC News 24 on Saturdays at 4:30 pm.

Catalyst celebrated its tenth year of production in 2010.

Description

The show broadcasts stories on scientific themes, and in particular significant recent developments and discoveries. It focuses primarily on stories relevant to Australia, but the series covers international developments as well. It attempts to convey information in a way that is not only accurate but also interesting and informative to the general population, often discussing the ethical, political, and other implications of scientific discoveries and research as well as the discoveries themselves.

The show's website describes it as follows:

Each week Catalyst brings you stories from Australia and around the world.