(a.) Belonging to the essence, or that which makes an object, or class of objects, what it is.
(a.) Hence, really existing; existent.
(a.) Important in the highest degree; indispensable to the attainment of an object; indispensably necessary.
(a.) Containing the essence or characteristic portion of a substance, as of a plant; highly rectified; pure; hence, unmixed; as, an essential oil.
(a.) Necessary; indispensable; -- said of those tones which constitute a chord, in distinction from ornamental or passing tones.
(a.) Idiopathic; independent of other diseases.
Example Sentences:
(1) However, medicines have an important part to play, and it is now generally agreed that for the very poor populations medicines should be restricted to those on an 'essential drugs list' and should be made available as cheaply as possible.
(2) The results of the evaluation confirm that most problems seen by first level medical personnel in developing countries are simple, repetitive, and treatable at home or by a paramedical worker with a few safe, essential drugs, thus avoiding unnecessary visits to a doctor.
(3) Nucleotide, which is essential for catalysis, greatly enhances the binding of IpOHA by the reductoisomerase, with NADPH (normally present during the enzyme's rearrangement step, i.e., conversion of a beta-keto acid into an alpha-keto acid, in either the forward or reverse physiological reactions) being more effective than NADP.
(4) Community involvement is a key element of the Primary Health Care (PHC) approach, and thus an essential topic on a course for managers of Primary Health Care programmes.
(5) No significant fatty acid binding by proteins was detected in S. cerevisiae, even when grown on a fatty acid-rich medium, thus indicating that such proteins are not essential to fatty acid metabolism.
(6) The UK's standard position on ICC indictees is to avoid all contact unless "essential".
(7) In spite of important differences in size, chemical composition, polymer density, and configuration, biological macromolecules indeed manifest some of the essential physical-chemical properties of gels.
(8) Most cis AB sera have anti-B activity, essentially at 4 degrees C. In saliva A and H substances are found in normal amounts but B substance is only evidenced by inhibition of autologous cells agglutination.
(9) Treatment with trypsin gave essentially one radioactive peptide, the active site peptide, of approximately 2300 molecular weight.
(10) We conclude that this enzyme is essentially identical to the native enzyme and should be very useful in the future study of this important hydroxylase.
(11) Thus serum ionized calcium in untreated essential hypertensive patients may predict the blood pressure response to the slow calcium channel blocker verapamil.
(12) The effects of supervised mild aerobic exercise at the work load of the blood lactate threshold for 10 weeks on serum lipids and apolipoproteins were studied in 24 patients with essential hypertension.
(13) No other essential regulatory sequence is located further upstream.
(14) Based on the results of the Community AIM Exploratory Action, further collaborative work is required at EEC level to create an Integrated Health Information Environment (IHE) allowing essentially for integration, modularity and security.
(15) Ovarian vein sampling for androgen was essential in locating this patient's microscopic tumor.
(16) After approximately 20 in vitro passages, Chinese hamster kidney (CHK) cell cultures transformed upon exposure to different strains of SV 40 can show a diploid modal chromosome number of 22 with chromosome counts exclusively or essentially in the diploid range (20-25).
(17) An official from Cafcass, the children and family court advisory service, tried to persuade the child in several interviews, but eventually the official told the court that further persuasion was inappropriate and essentially abusive.
(18) Of 55 new open reading frames analysed by gene disruption, three are essential genes; of 42 non-essential genes that were tested, 14 show some discernible effect on phenotype and the remaining 28 have no overt function.
(19) Essential characteristics of the composite bone cement included a homogeneous and uniform fiber distribution, and a minimal increase in apparent viscosity of the polymerizing cement.
(20) The median blood levels were lower in hyperacidic subjects and higher in hypoacidic patients; the urinary excretion of the digitalis compound showed no essential differences.
Penumbra
Definition:
(n.) An incomplete or partial shadow.
(n.) The shadow cast, in an eclipse, where the light is partly, but not wholly, cut off by the intervening body; the space of partial illumination between the umbra, or perfect shadow, on all sides, and the full light.
(n.) The part of a picture where the shade imperceptibly blends with the light.
Example Sentences:
(1) Our analysis showed that the interpolation errors are proportional to the curvature of the dose distribution and are relatively high in regions on either side of, but not including, the steepest part of the penumbra.
(2) Analysis of the penumbra width of cross dose distributions, as a function of field sizes, allowed us to postulate that the dmax shift could be due to the phantom scattered photons, which in turn were generated by the collimator scattered photons.
(3) If true, this is the first demonstration of the ischemic penumbra by MR imaging and may reflect our use of Wistar rats, a new image analysis technique, and ultra-high resolution MR imaging.
(4) The combination for this applicator of sharp penumbra and low out-of-field dose leads to reduced lung and opposite breast doses.
(5) An extracellular acidosis that occurs in the penumbra zone was investigated in vitro as to its role in the formation of cytotoxic cell swelling.
(6) The ischemic thresholds for the initial increase in CMRG and the complete depletion of ATP content represent the metabolic equivalent of the penumbra zone and provide a basis for the evaluation of therapeutic procedures for the treatment of stroke.
(7) If the entire cross-section is blocked, the point will be in the umbra of the shadow; if only a portion of the light is blocked, the point will be in the penumbra of the shadow.
(8) The mechanisms involved in this sequence of events and the role of pH changes in the development of the so-called "ischaemic penumbra" are discussed.
(9) In the light of these findings, we suggest that use of a selective antagonist of LTs may be helpful in reducing the ischemic penumbra during acute cerebral ischemia by controlling the vasogenic edema.
(10) Opening the hinge adjustment restores field flatness, without changing penumbra or the inverse square law behavior of the teletherapy unit.
(11) The area of "penumbra" could be estimated in regions with CBF value just above this threshold.
(12) In the penumbra zone, comparable trends were noted in OER and CMRO2 but the difference in the changes between the two groups did not reach statistical significance.
(13) The agreement is within experimental errors both in the penumbra region and along the central ray of the asymmetric field.
(14) These results confirm the concept of a metabolic penumbra.
(15) These wedges were designed to increase the penumbra width at the field junction from about 1.5 to about 3.5 cm, to achieve dose uniformity.
(16) These studies suggest that 1) the expression of 72-kd heat-shock protein in neurons precedes the development of ischemic cellular alterations detectable by conventional hematoxylin and eosin light microscopy methods; 2) there is a hierarchy of cell types and anatomic sites that express 72-kd heat-shock protein, and this hierarchy reflects cellular and anatomic vulnerability to ischemic cell damage; and 3) 72-kd heat-shock protein induction in neurons bordering a necrotic ischemic core may be the morphological equivalent of the ischemic penumbra.
(17) While within the penumbra, some direct sunlight falls on the Moon but little darkening of the disc will be noticed until a few minutes before the Moon begins to enter the umbra at 19:23.
(18) Measurements with the diode interfaced to an X-Y recorder required only a fraction of the time required with the chambers, minimizing error due to change in machine output, and permitted resolution of isodose lines in the penumbra.
(19) A typical spot has a central dark umbra, surrounded by a lighter penumbra.
(20) The rate in the penumbra differed (P = .01) from that in the predicted low-dose region, where scotoma did not increase with time.