Definitions beginning with U

(ul'truh-sound) mechanical radiant energy. Ultrasonography allows the visualization of deep structures of the body by recording the reflections of (echoes of) pulses of ultrasonic waves directed into the tissues. For more information, see Ultrasound.
DoD Breast Health Program South - Cite This Source - This Definition
Browse Related Terms: Computed Tomography, Differientiated, endometrial, Margins, placebo, S-phase fraction, Tumor

ultrasound biomicroscopy - permalink - collapse

All > Medicine > Cancer

(UL-truh-SOWND BY-oh-my-KROS-koh-pee) A type of ultrasound eye exam that makes a more detailed image than regular ultrasound. High-energy sound waves are bounced off the inside of the eye and the echo patterns are shown on the screen of an ultrasound machine. This makes a picture called a sonogram.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: endorectal ultrasound, endoscopic ultrasound, endoscopic ultrasound-guided fine needle aspiration, endosonography, ERUS, EUS, HIFU, high-intensity focused ultrasound therapy, sonogram, transabdominal ultrasound, transrectal ultrasound, transvaginal sonography, transvaginal ultrasound, TRUS, TVS, ultrasonogram, ultrasonography, ultrasound, ultrasound transducer

ultrasound energy - permalink - collapse

All > Medicine > Cancer

A form of therapy being studied as an anticancer treatment. Intensified ultrasound energy can be directed at cancer cells to heat them and kill them.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: adverse event, behavior modification, Gonzalez regimen, medical nutrition therapy, moxibustion, Nausea, nutrition therapy

ultrasound-guided biopsy - permalink - collapse

All > Medicine > Cancer

(BY-op-see) A biopsy procedure that uses an ultrasound imaging device to find an abnormal area of tissue and guide its removal for examination under a microscope.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: aspiration, biopsy, biopsy specimen, bone marrow aspiration, bone marrow biopsy, cone biopsy, conization, core biopsy, endometrial biopsy, EUS-FNA, excisional biopsy, fine-needle aspiration biopsy, FNA biopsy, histologic examination, incisional biopsy, lung biopsy, Mammotome, needle biopsy, needle-localized biopsy, open biopsy, punch biopsy, seminal vesicle biopsy, shave biopsy, stereotactic biopsy, surgical biopsy, transperineal biopsy, transrectal biopsy, transurethral biopsy

ultrasound transducer - permalink - collapse

All > Medicine > Cancer

A device that produces sound waves that bounce off body tissues and make echoes. The transducer also receives the echoes and sends them to a computer that uses them to create a picture called a sonogram. Transducers (probes) come in different shapes and sizes for use in making pictures of different parts of the body. The transducer may be passed over the surface of the body or inserted into an opening such as the rectum or vagina.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: endorectal ultrasound, endoscopic ultrasound, endoscopic ultrasound-guided fine needle aspiration, endosonography, ERUS, EUS, HIFU, high-intensity focused ultrasound therapy, sonogram, transabdominal ultrasound, transrectal ultrasound, transvaginal sonography, transvaginal ultrasound, TRUS, TVS, ultrasonogram, ultrasonography, ultrasound, ultrasound biomicroscopy

Ultraviolet Index - permalink - collapse

All > Science > Weather

This index provides important information to help you plan your outdoor activities in ways that prevent overexposure to the sun's rays. It was designed by the National Weather Service (NWS) and the Environmental Protection Agency (EPA). Unlike some countries' indices, the United States UV Index is not based upon surface observations. Rather, it is computed using forecasted ozone levels, a computer model that relates ozone levels to UV incidence on the ground, forecasted cloud amounts, and the elevation of the forecast cities. The calculation starts with measurements of current total ozone amounts for the entire globe, obtained via two satellites operated by the National Oceanic and Atmospheric Administration (NOAA). These data are then used to produce a forecast of ozone levels for the next day at various points around the country.

Category	UV Index	Time to Burn	Actions to Take
Minimal	0 - 2	60 min. +	Apply SPF sunscreen.
Low	3 - 4	45 min.	Apply SPF sunscreen, wear a hat.
Moderate	5 - 6	30 min.	Apply SPF 15, wear a hat.
High	7 - 9	15 - 24 min.	Apply SPF 15 to 30, wear a hat and sunglasses. Limit midday exposure.
Very High	10+	10 min.	Apply SPF 30; wear a hat, sunglasses, and protective clothing; limit midday exposure.

NOAA National Weather Service - Cite This Source - This Definition

Browse Related Terms: DTRT, EPA, Prevention of Significant Deterioration, UV Index, Visibility Protection Program

ultraviolet radiation - permalink - collapse

All > Medicine > Cancer

(UL-truh-VY-oh-let RAY-dee-AY-shun) Invisible rays that are part of the energy that comes from the sun. Ultraviolet radiation also comes from sun lamps and tanning beds. It can damage the skin and cause melanoma and other types of skin cancer. Ultraviolet radiation that reaches the Earth's surface is made up of two types of rays, called UVA and UVB rays. UVB rays are more likely than UVA rays to cause sunburn, but UVA rays pass deeper into the skin. Scientists have long thought that UVB radiation can cause melanoma and other types of skin cancer. They now think that UVA radiation also may add to skin damage that can lead to skin cancer and cause premature aging. For this reason, skin specialists recommend that people use sunscreens that reflect, absorb, or scatter both kinds of ultraviolet radiation. Also called UV radiation.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: phototesting, sunscreen, UV radiation, UVA radiation, UVB radiation

All > Science > Climate Change

Ultraviolet radiation Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays; roughly, radiation in the wavelength interval from 10 to 4000 angstroms.
NSIDC - Cite This Source - This Definition
Browse Related Terms: Absorption of radiation, Heat balance of the Earth-atmosphere system, insolation, Mount Pinatubo, Photovoltaic and solar thermal energy, radiation, Solar energy, Solar Radiation, solar variability, Ultraviolet Radiation (UV)

All > Science > Weather

Electromagnetic radiation of shorter wavelength than visible radiation but longer than x-rays.
NOAA National Weather Service - Cite This Source - This Definition
Browse Related Terms: blackbody, Blackbody Radiation, dispersion, gamma ray, Graybody, Longwave Radiation, Microwave, Photosphere, radiation, Radiation Laws, Shortwave radiation, Visual Spectrum, X-Rays

ultraviolet radiation therapy - permalink - collapse

All > Medicine > Cancer

(UL-truh-VY-oh-let RAY-dee-AY-shun THAYR-uh-pee) A form of radiation used in the treatment of cancer.
National Cancer Institute - Cite This Source - This Definition
Browse Related Terms: charged-particle radiation therapy, electron beam, external-beam radiation therapy, external radiation therapy, fast-neutron beam radiation, intensity-modulated radiation therapy, intraoperative radiation therapy, ionizing radiation, photon-beam radiation, plaque radiotherapy, proton beam radiation therapy, radiation necrosis, radiation oncologist, radioimmunotherapy, radiosensitization, radiosensitizer, systemic radiation therapy, unsealed internal radiation therapy, x-ray therapy

Ultraviolet Radiation (UV) - permalink - collapse

All > Science > Climate Change

A portion of the electromagnetic spectrum with wavelengths shorted than visible light. The sun produces UV, which is commonly split into three bands of decreasing wavelength. Shorter wavelength radiation has a greater potential to cause biological damage on living organisms. The longer wavelength ultraviolet band, UVA, is not absorbed by ozone in the atmosphere. UVB is mostly absorbed by ozone, although some reaches the Earth. The shortest wavelength band, UVC, is completely absorbed by ozone and normal oxygen in the atmosphere.
EPA - Cite This Source - This Definition
The energy range just beyond the violet end of the visible spectrum. Although ultraviolet radiation constitutes only about 5 percent of the total energy emitted from the sun, it is the major energy source for the stratosphere and mesosphere, playing a dominant role in both energy balance and chemical composition.

Most ultraviolet radiation is blocked by Earth's atmosphere, but some solar ultraviolet penetrates and aids in plant photosynthesis and helps produce vitamin D in humans. Too much ultraviolet radiation can burn the skin, cause skin cancer and cataracts, and damage vegetation.
EPA - Cite This Source - This Definition
Browse Related Terms: Absorption of radiation, Heat balance of the Earth-atmosphere system, insolation, Mount Pinatubo, Photovoltaic and solar thermal energy, radiation, Solar energy, Solar Radiation, solar variability, ultraviolet radiation

Ultraviolet (UV) - permalink - collapse

All > Technology > Defense

Electromagnetic radiation of wavelength between the shortest visible violet (about 3,850 Angstroms) and soft x-rays (about 100 Angstroms).
DoD Missile Defense Agency - Cite This Source - This Definition
Browse Related Terms: Coherence, CRT, Electromagnetic Radiation (EMR), gamma ray, ionizing radiation, Nuclear Radiation, radiation, Radioactivity, Scattering, Thermal X-Rays, X-Rays

All > Technology > Telecommunications

The portion of the electromagnetic spectrum in which the longest wavelength is just below the visible spectrum, extending from approximately 4 nm to approximately 400 nm. Note: Some authorities place the lower limit of uv at values between 1 and 40 nm, 1 nm being the upper wavelength limit of x-rays. The 400-nm limit is the lowest visible wavelength, i.e., the highest visible frequency, violet. See electromagnetic spectrum.
ATIS - Cite This Source - This Definition
Browse Related Terms: Infrared (IR), spectrum, visible spectrum, wireless