Chief mateA chief mate (C/M) or chief officer, usually also synonymous with the first mate or first officer, is a licensed mariner and head of the deck department of a merchant ship. The chief mate is customarily a watchstander and is in charge of the ship's cargo and deck crew. The actual title used will vary by ship's employment, by type of ship, by nationality, and by trade: for instance, chief mate is not usually used in the Commonwealth, although chief officer and first mate are; on passenger ships, the first officer may be a separate position from that of the chief officer that is junior to the latter.
FeedbackFeedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to feed back into itself. The notion of cause-and-effect has to be handled carefully when applied to feedback systems: Simple causal reasoning about a feedback system is difficult because the first system influences the second and second system influences the first, leading to a circular argument.
Rate of natural increaseIn Demography, the rate of natural increase (RNI), also known as natural population change, is defined as the birth rate subtracted by the death rate of a particular population, over a particular time period. It is typically expressed either as a number per 1,000 individuals in the population or as a percentage. RNI can be either positive or negative. It contrasts to total population change by ignoring net migration. This RNI gives demographers an insight into how a region's population is evolving, and these analyses can inform government attempts to shape RNI.
ReproductionReproduction (or procreation or breeding) is the biological process by which new individual organisms – "offspring" – are produced from their "parent" or parents. Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual. In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms.
Canalisation (genetics)Canalisation is a measure of the ability of a population to produce the same phenotype regardless of variability of its environment or genotype. It is a form of evolutionary robustness. The term was coined in 1942 by C. H. Waddington to capture the fact that "developmental reactions, as they occur in organisms submitted to natural selection...are adjusted so as to bring about one definite end-result regardless of minor variations in conditions during the course of the reaction".
Third mateA third mate (3/M) or third officer is a licensed member of the deck department of a merchant ship. The third mate is a watchstander and customarily the ship's safety officer and fourth-in-command (fifth on some ocean liners). The position is junior to a second mate. Other duties vary depending on the type of ship, its crewing, and other factors. Duties related to the role of safety officer focus on responsibility for items such as firefighting equipment, lifeboats, and various other emergency systems.
Second mateA second mate (2nd mate) or second officer (2/O) is a licensed member of the deck department of a merchant ship holding a Second Mates Certificate of Competency, which is issued by the administration. The second mate is the third in command (or on some ocean liners fourth) and a watchkeeping officer, customarily the ship's navigator. Other duties vary, but the second mate is often the medical officer and in charge of maintaining distress signaling equipment. On oil tankers, the second mate usually assists the chief mate with the cargo operations.
Population ecologyPopulation ecology is a sub-field of ecology that deals with the dynamics of species populations and how these populations interact with the environment, such as birth and death rates, and by immigration and emigration. The discipline is important in conservation biology, especially in the development of population viability analysis which makes it possible to predict the long-term probability of a species persisting in a given patch of habitat.
Sexual revolutionThe sexual revolution, also known as the sexual liberation, was a social movement that challenged traditional codes of behavior related to sexuality and interpersonal relationships throughout the developed Western world from the 1960s to the 1970s. Sexual liberation included increased acceptance of sex outside of traditional heterosexual, monogamous relationships (primarily marriage). The normalization of contraception and the pill, public nudity, pornography, premarital sex, homosexuality, masturbation, alternative forms of sexuality, and the legalization of abortion all followed.
Climate change feedbackClimate change feedbacks are effects of global warming that amplify or diminish the effect of forces that initially cause the warming. Positive feedbacks enhance global warming while negative feedbacks weaken it. Feedbacks are important in the understanding of climate change because they play an important part in determining the sensitivity of the climate to warming forces. Climate forcings and feedbacks together determine how much and how fast the climate changes.
