Hereditary angioedema (HAE) is a rare genetic disorder characterized by recurrent painful swellings of the skin and mucous membranes. Without treatment, patients’ quality of life is noticeably compromised: Angioedema may not only be disfiguring; in the gastrointestinal tract it may lead to severe abdominal colic ad in the upper airways it can even be fatal if left untreated. The frequency of angioedema attacks is unpredictable and varies from patient to patient; swellings may occur up to several times a week. The disorder affects about one to two in a hundred thousand people. 

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The exact science of tree sap transport has puzzled plant physiologists for many years. Sap’s migration throughout tree trunks and branches is linked heavily to transpiration, the movement and subsequent evaporation of moisture from plants. As carbon dioxide diffuses inward from the air to plant leaves, a vapor pressure deficit between the leaf interior and surrounding atmosphere causes evaporation. This generates tension within leaf cell walls that is then transmitted via sap to tracheids — conductive hollow wood cells with vertical grooves that comprise the trunk, stem, and branches of trees and are collectively called sapwood. The resulting negative sap pressure draws water from roots to leaves, sometimes to heights of over 300 feet. 

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In summer 2018 the planets Mars and Saturn are, one after the other, in opposition to Earth. During this event the planets are relatively close to Earth, allowing astronomers to observe them in greater detail. Hubble took advantage of this preferred configuration and imaged both planets to continue its long-standing observation of the outer planets in the Solar System.

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