Spelling differences in the context of "Comparison of American and British English"

Animal fibers or animal fibres (see spelling differences) are natural fibers that consist largely of certain proteins. Examples include silk, hair/fur (including wool) and feathers. The animal fibers used most commonly both in the manufacturing world as well as by the hand spinners are wool from domestic sheep and silk. Also very popular are alpaca fiber and mohair from Angora goats. Unusual fibers such as Angora wool from rabbits and Chiengora from dogs also exist, but are rarely used for mass production.

Not all animal fibers have the same properties, and even within a species the fiber is not consistent. Merino is a very soft, fine wool, while Cotswold is coarser, and yet both Merino and Cotswold are types of sheep. This comparison can be continued on the microscopic level, comparing the diameter and structure of the fiber. With animal fibers, and natural fibers in general, the individual fibers look different, whereas all synthetic fibers look the same. This provides an easy way to differentiate between natural and synthetic fibers under a microscope.

Natural fibers or natural fibres (see spelling differences) are fibers that are produced by geological processes, or from the bodies of plants or animals. They can be used as a component of composite materials, where the orientation of fibers impacts the properties. Natural fibers can also be matted into sheets to make paper or felt.

The earliest evidence of humans using fibers is the discovery of wool and dyed flax fibers found in a prehistoric cave in the Republic of Georgia that date back to 36,000 BP. Natural fibers can be used for high-tech applications, such as composite parts for automobiles and medical supplies. Compared to composites reinforced with glass fibers, composites with natural fibers have advantages such as lower density, better thermal insulation, and reduced skin irritation. Further, unlike glass fibers, natural fibers can be broken down by bacteria once they are no longer used.

Wood fibres (also spelled wood fibers, see spelling differences) are usually cellulosic elements that are extracted from trees and used to make materials including paper.

The end paper product (paper, paperboard, tissue, cardboard, etc.) dictates the species, or species blend, that is best suited to provide the desirable sheet characteristics, and also dictates the required fibre processing (chemical treatment, heat treatment, mechanical "brushing" or refining, etc.).

Greywater (or grey water, sullage, also spelled gray water in the United States) refers to domestic wastewater generated in households or office buildings from streams without fecal contamination, i.e., all streams except for the wastewater from toilets. Sources of greywater include sinks, showers, baths, washing machines or dishwashers. As greywater contains fewer pathogens than blackwater, it is generally safer to handle and easier to treat and reuse onsite for toilet flushing, landscape or crop irrigation, and other non-potable uses. Greywater may still have some pathogen content from laundering soiled clothing or cleaning the anal area in the shower or bath.

The application of greywater reuse in urban water systems provides substantial benefits for both the water supply subsystem, by reducing the demand for fresh clean water, and the wastewater subsystems by reducing the amount of conveyed and treated wastewater. Treated greywater has many uses, such as toilet flushing or irrigation.

Submillimetre astronomy or submillimeter astronomy (see spelling differences) is the branch of observational astronomy that is conducted at submillimetre wavelengths (i.e., terahertz radiation) of the electromagnetic spectrum. Astronomers place the submillimetre waveband between the far-infrared and microwave wavebands, typically taken to be between a few hundred micrometres and a millimetre. It is still common in submillimetre astronomy to quote wavelengths in 'microns', the old name for micrometre.

Submillimetre observations can be used to trace emission from gas and dust, including the CI, CO, and CII lines. Sources behind this emission include molecular clouds and dark cloud cores, which can be used to clarify the process of star formation from earliest collapse to stellar birth, by determining chemical abundances in dark clouds and the cooling mechanisms for the molecules which comprise them. Other sources include protoplanetary discs, dusty starburst galaxies in the early Universe, immediate environments surrounding AGN, and secondary anisotropies in the cosmic microwave background.

In hematology, hemophagocytic lymphohistiocytosis (HLH), also known as haemophagocytic lymphohistiocytosis (British spelling), and hemophagocytic or haemophagocytic syndrome, is an uncommon hematologic disorder seen more often in children than in adults. It is a life-threatening disease of severe hyperinflammation caused by uncontrolled proliferation of benign lymphocytes and macrophages that secrete high amounts of inflammatory cytokines. It is classified as one of the cytokine storm syndromes.

There are inherited (primary HLH) and acquired (secondary HLH) forms. The inherited form is due to genetic mutations and usually presents in infants and children, with a median age of onset of 3-6 months. Familial HLH is an autosomal recessive disease, hence each sibling of a child with familial HLH has a twenty-five–percent chance of developing the disease, a fifty-percent chance of carrying the defective gene (which is very rarely associated with any risk of disease), and a twenty-five–percent chance of not being affected and not carrying the gene defect.Genes that are commonly mutated in those with primary HLH lead to defective lymphocyte (natural killer cell and cytotoxic T-cell) function. The mutated genes are PRF1 (perforin-1), UNC13D, STX11, and STXBP2. Secondary HLH usually presents in adulthood (usually in people with genetic changes predisposing them to the disease) after exposure to a trigger. Common triggers leading to secondary HLH include infections, cancer, or autoimmune diseases. The incidence of all forms of HLH was estimated to be 4.2 cases per 1 million people in a population based study from England in 2018, but the true incidence is not known. The incidence of HLH (especially secondary HLH) is thought to be underestimated as the clinical signs and symptoms are very similar to sepsis.