Organic chemistry is a chemistry subdiscipline involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms. Study of structure includes using spectroscopy and other physical and chemical methods to determine the chemical composition and constitution of organic compounds and materials. Study of properties includes both physical properties and chemical properties, and uses similar methods as well as methods to evaluate chemical reactivity, with the aim to understand the behavior of the organic matter in its pure form (when possible), but also in solutions, mixtures, and fabricated forms. The study of organic reactions includes both their preparation—by synthesis or by other means—as well as their subsequent reactivities, both in the laboratory and via theoretical (in silico) study.
The range of chemicals studied in organic chemistry include hydrocarbons, compounds containing only carbon and hydrogen, as well as compositions based on carbon but containing other elements. Organic chemistry overlaps with many areas including medicinal chemistry, biochemistry, organometallic chemistry, and polymer chemistry, as well as many aspects of materials science.
Hormonal contraception refers to birth control methods that act on the endocrine system. Almost all methods are composed of steroid hormones, although in India one selective estrogen receptor modulator is marketed as a contraceptive. The original hormonal method—the combined oral contraceptive pill—was first marketed as a contraceptive in 1960. In the ensuing decades many other delivery methods have been developed, although the oral and injectable methods are by far the most popular. Altogether, 18% of the world's contraceptive users rely on hormonal methods. Hormonal contraception is highly effective: when taken on the prescribed schedule, users of steroid hormone methods experience pregnancy rates of less than 1% per year. Perfect-use pregnancy rates for most hormonal contraceptives are usually around the 0.3% rate or less. Currently available methods can only be used by women; the development of a male hormonal contraceptive is an active research area.
There are two main types of hormonal contraceptive formulations: combined methods which contain both an estrogen and a progestin, and progestogen-only methods which contain only progesterone or one of its synthetic analogues (progestins). Combined methods work by suppressing ovulation and thickening cervical mucus; while progestogen-only methods reduce the frequency of ovulation, most of them rely more heavily on changes in cervical mucus. The incidence of certain side effects is different for the different formulations: for example, breakthrough bleeding is much more common with progestogen-only methods. Certain serious complications occasionally caused by estrogen-containing contraceptives are not believed to be caused by progestogen-only formulations: deep vein thrombosis is one example of this.
Mergers and acquisitions (abbreviated M&A) is an aspect of corporate strategy, corporate finance and management dealing with the buying, selling, dividing and combining of different companies and similar entities that can help an enterprise grow rapidly in its sector or location of origin, or a new field or new location, without creating a subsidiary, other child entity or using a joint venture.
The distinction between a "merger" and an "acquisition" has become increasingly blurred in various respects (particularly in terms of the ultimate economic outcome), although it has not completely disappeared in all situations. From a legal point of view, a merger is a legal consolidation of two companies into one entity, whereas an acquisition occurs when one company takes over another and completely establishes itself as the new owner (in which case the target company still exists as an independent legal entity controlled by the acquirer). Either structure can result in the economic and financial consolidation of the two entities. In practice, a deal that is an acquisition for legal purposes may be euphemistically called a "merger of equals" if both CEOs agree that joining together is in the best interest of both of their companies, while when the deal is unfriendly (that is, when the target company does not want to be purchased) it is almost always regarded as an "acquisition".