Lumen unit

Value is based on assumption that transport from gut tissue represents about 79% of total methyl mercury transport to gut lumen. Units are mL tissue/min/g tissue. h Value represents the average rate of Gl mucosal cell exfoliation. Estimated from Bertalanffy (1960). 

Lumen Unit of luminous flux falling on a square centimeter at a distance of one centimeter from one international candle, cell cavity, passageway, or opening. 

Lumens- Unit of measure for total light output. The amount of light falling on a surface of one square foot. 

Under the common system, it was defined as the flux on one square foot of a sphere, one foot in radius, with a light source of one candle at the center that radiates uniformly in all directions. Under SI, luminous flux is measured in lumen units (symbol Im) and has as its formula cd x sr, which are the SI Base Units of candela and stera-dian for a solid angle. Thus, the lumen is the luminous flux emitted in a solid angle of one lumen nniformly distributed in a solid angle of one steradian by a point source having a nniform intensity of one candela. See also LUX. 

The standard unit of light measurement (the light flux) is the lumen, which is the amount of energy (power, watts) emitted or received (Joules per second). At 555 nm, 1 lumen = 0.00147 watts = 0.00147 J.s-1. This is sometimes called a lightwatt . 

If the amount of light is measured over an area of receiving surface, the energy falling on the surface is measured in lumens per unit area ( lux" or phof). Thus, the number of lux = Iumens/m2 and this measures the power received per square meter of surface (energy per second/per unit area) and phot = Iumens/cm2 and measures the light power received per square centimeter of surface. 

Thus, we have two units of measurement of intensity. One is related to scattering from a surface, L, i.e.- in foot-lamberts and the other is related to emittance, H, i.e.- in lumens per square foot. Although we have assumed "white" light up to now, either of these two can be wavelength dependent. If either is wavelength dependent, then we have a pigment (reflective- but more properly called scattering) with intensity in foot-lamberts, or an emitter such as a lamp or phosphor (emittance) with intensity in lumens. 

The food, now in a liquid form known as chyme, passes through the pyloric sphincter into the duodenum, where stomach acid is neutralized. There is wide variation in lengths of the components of the small intestine (i.e., duodenum, jejunum, and ileum) between individuals (Table 98-1). Most absorption of digested carbohydrate and protein occurs within the jejunum. Most fat absorption occurs within the jejunum and ileum. In the small bowel, breakdown of macronutrients (i.e., carbohydrate, protein, and fat) occurs both within the lumen of the gut and at the intestinal mucosal membrane surface. The absorptive units on the intestinal mucosal membrane are infoldings known as... 

The surface area in the luminal side of the small intestine per unit length of the serosal (blood) side is enormous in the proximal jejunum, and steadily decreases (to about 20% of the starting value [62]) in the distal portions of the small intestine. The surface area is increased threefold [69] by ridges oriented circumferentially around the lumen. Similar folds are found in all segments of the GIT, except the mouth and esophagus [66]. Further 4—10-fold expansion [62,69] of the surface is produced by the villi structures, shown schematically in Fig. 2.4. The layer of epithelial cells lining the villi structures separate the lumen from the circulatory system. Epithelial cells are made in the crypt folds of the villi, and take about... 

FIGURE 1.33 Top left membrane unit with 1 mL channel volume (A = inert material B = membrane) Top right membrane unit with 10 flh channel volume. Bottom hollow fiber membrane unit with 1.3 /rL acceptor channel (lumen) volume.151 (Reproduced with permission from IUPAC.)... 

In human eye units, watt becomes lumen. At 555 nm, the peak sensitivity of the photopic response, there are 683 lm/W. A watt is a joule per second, and a photon has energy in units of joules. A watt tells us how many photons per second are coming out of the OLED. A lumen... 

The luminous efficiency is the simplest to calculate. It is the ratio of the luminance (cd/m2) to the current density (A/m2), and has units of cd/A. Finally, the power efficiency is the ratio of the light output in lumens divided by the electrical input in watts. For reference, a typical incandescent light bulb is 151m/W, while a fluorescent light bulb is 601m/W. 

Myoepithelial cells are contractile elements found in salivary, sweat, and mammary glands that show a combined smooth muscle and epithelial phenotype (Foschini et al. 2000). In the normal breast, the ductal and acinar units are lined by two cell layers the inner layer lining the lumen and an outer layer of myoepithelial cells. An intact myoepithelial cells layer is seen in both benign and in situ lesions, whereas loss of the myoepithelial cells layer is considered the rule for the diagnosis of invasive cancer (Kalof et al. 2004 and citations therein). 

The blood first reaches the glomerulus, the filter unit of the nephron. The glomerular filtrate, i.e. blood deprived of macromolecules and blood cells, passes through the tubular lumen. The blood which is not filtered, flows through the efferent arteriole into the network of capillaries around the tubules suppl5dng the proximal and distal tubules with blood. 

The SI unit of luminous flux, abbreviated hn. One lumen is the amount of luminous flux emitted in a unit solid angle of one steradian by a uniform point source having a luminous intensity of one candela. 2. The interior space of a tubular structure such as an intestine or artery. 

Thyroid epithelial cells synthesize and secrete T4 and T3 and make up the functional units of thyroid glandular tissue, the thyroid follicles. Thyroid follicles are hollow vesicles formed by a single layer of epithelial cells that are filled with colloid. T4,T3, and iodine are stored in the follicular colloid. T4 and T3 are derived from tyrosyl residues of the protein thyroglobulin (Tg). Thyroid follicular cells synthesize and secrete Tg into the follicular lumen. Thyroid follicular cells also remove iodide (I ) from the blood and concentrate it within the follicular lumen. Within the follicles, some of the tyrosyl residues of Tg are iodinated, and a few specific pairs of iodoty-rosyl residues may be coupled to form T4 and T3. Thus, T4, T3, and iodine (in the form of iodinated tyrosyl residues) are found within the peptide structure of the Tg that is stored in the follicular lumen. 

The units of L are lumens If E Is expressed in watts The product yE thus represents a figure of merit for phosphors y is... 

Antacids are basic compounds that neutralise acid in gastric lumen, have no effect on gastric acid secretion. They are quantitatively compared in terms of their acid neutralizing capacity (ANC), which is defined as the quantity of 1 N HCl (in MEq) that can be brought to pH 3.5 in 15 minutes by a unit dose of antacid preparation. An ideal antacid should be potent in neutralizing acid, inexpensive, not absorbed from GIT and contain negligible amounts of sodium, should be sufficiently palatable to be readily tolerated with repeated dosage and should be free of side effects. An ideal antacid is yet to be developed. 

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