acute, self-limited, systemic disease caused by the rickettsia Coxiella burnetii. Q fever spreads rapidly in cows, sheep, and goats, and in humans it tends to occur in localized outbreaks. The clinical symptoms are those of fever, chills, ...

QĀḌĪ. A qāḍī is a judge responsible for the application of Islamic positive law (fiqh). The office originated under the rule of the first Umayyad caliphs (AH 40–85/661–705 CE), when t...

The Qajar dynasty in Persia (present-day Iran) spanned 130 years, beginning with Agha Mohammad Qajar in 1795 and ending with Ahmad Shah in 1925. It was a period in Persian history that saw substantial British and Russian regional influence...

(1998 est. pop. 190,000). Karshi, in the southern part of the republic of Uzbekistan in Central Asia, is an ancient city on the old trade route between Afghanistan and Samarqand. Situated in a fertile oasis of the Kashka Darya River, today...

In Chinese philosophy, the ethereal substance of which everything is composed. Early Daoist philosophers and alchemists regarded it as a vital force associated with breath and bodily fluids and sought to control its movement within the bod...

Qigong refers to Chinese mental and physical exercises that cultivate qi (ch'i). Daoist in origin and often associated with healing, longevity, and enlightenment, these practices increase suppleness, develop relaxation, and improve ...

(born &circa; 259 &BC;, Qin state, northwestern China—died 210 &BC;, Hebei province) Founder of the Qin dynasty (221–207 &BC;). His father was king of Qin, which was regarded as barbarous by the central states of China but had ...

Province (pop., 2002 est.: 5,290,000), northwestern China. It is bordered by Gansu and Sichuan provinces and the Tibet and Xinjiang autonomous regions.With an area of 278,400 sq mi (721,000 sq km), it is the fourth largest political subdiv...

Qingming is the second-most-important seasonal festival, after the Lunar New Year, involving ancestral veneration in China. The term literally means clear and transparent, or brightness, implying the arrival of spring, after the dark and c...

(1875–1907), Chinese revolutionary and advocate of women's rights. Qiu Jin (Ch'iu Chin) was born into a well-to-do family in China's Shaoxing, Zhejiang Province. She received a good education, but at the age of ...

(2001 pop. 873,000). Approximately 130 kilometers south of Tehran, Qom is situated in a semiarid interior basin of central Iran along the Qom River, which flows down from the Zagros Mountains, through Qom, and into the large Darya-e Namak ...

Algebraic equation of particular importance in optimization. A more descriptive name is second-degree polynomial equation. Its standard form is &math.a;&math.x;2 + &math.b;&math.x; + &math.c; = 0, and its solution is given by the quadratic...

Quadriplegia A complete paralysis of the arms, legs, and trunk, usually occurring after a severe injury to the spinal cord between the fifth and seventh vertebrae. Spastic quadriplegia is a condition present at birth often accompanied by v...

Qualia The word quale (or qualia ) derives from the Latin for "quality." As used by C. I. Lewis (1929) and those following him, it refers to the qualities of phenomenal individuals, such as color patches, tastes, and sounds. ...

Qualitative analysis involves determining the composition of an unknown compound or mixture. Qualitative analysis can also analyze a mixture to determine the precise percentage composition of the sample in terms of elements, radicals, and ...

Quality management (QM), also called total quality management (TQM), evolved from many different management practices and improvement processes. Quality management is not specific to managing people, but rather is related to improving the ...

The Quan Tangshi (Complete Tang Poems) is the most complete collection of Tang dynasty (618–907 CE) and Five Dynasties (907–960 CE) verse. It consists of 900 fascicles, with 48,900 works by more than 2,200 writers. The compil...

Quantitative analysis involves measuring the proportions of known components in a mixture. Whereas qualitative analysis involves identifying what materials are present in a sample (quality), quantitative analysis involves determining how m...

Quantitative traits are those that vary continuously. This is in contrast to qualitative traits, in which the phenotype is discrete and can take on one of only a few different values. Examples of quantitative traits include height, weight,...

Quantum chemistry involves the application of the principles of quantum theory to chemistry. Quantum chemistry helps predict the way atoms combine to form molecules, and the way molecules interact with each other. Applications of quantum c...

device that employs properties described by quantum mechanics to enhance computations. As early as 1959 the American physicist and Nobel laureate Richard Feynman noted that, as electronic components begin to reach microscopic scales, effec...

Quantum theory of the interactions of charged particles with the electromagnetic field. It describes the interactions of light with matter as well as those of charged particles with each other. Its foundations were laid by P. A. M. Dirac w...

Relativity and quantum theory, the foundations upon which all of modern physics rests, were developed in the first quarter of the twentieth century. Their accuracy in predicting the results of experiment or observation is astounding; the s...

Branch of mathematical physics that deals with atomic and subatomic systems. It is concerned with phenomena that are so small-scale that they cannot be described in classical terms, and it is formulated entirely in terms of statistical pro...

A quantum state is the condition a quantum mechanical system is in. The state is usually described by a wave function. It is different from classical states of systems in that the quantum system has separate, discrete levels, whereas the s...