| cathode ray tube | An evacuated tube containing a beam of electrons which can be deflected to various parts of a fluorescent screen; used in the cathode ray oscilloscope. (05 Mar 2000) |
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| cathode ray | <physics> Electrons emitted from the surface of a cathode in a vacuum tube. (16 Mar 1998) |
| cathode | <chemistry, physics> The electrode in an electrochemical cell toward which cations are drawn and where reduction occurs. The negatively charged electrode in a vacuum tube. (16 Mar 1998) |
| cathode rays | A stream of electrons emitted from the negative electrode (cathode) in a Crookes tube; their bombardment of the anode or the glass wall of the tube gives rise to X-ray's. (05 Mar 2000) |
| persistent | Continuing to exist in spite of interference or treatment, tending to recur. (18 Nov 1997) |
| persistent anterior hyperplastic primary vitreous | A unilateral congenital abnormality occurring in full-term infants; characterised by a retrolental fibrovascular membrane formed by persistent primary vitreous with remnants of the hyaloid artery and tunica vasculosa lentis; associated with leukokoria, microphthalmos, shallow anterior chamber, and elongated ciliary processes. (05 Mar 2000) |
| persistent atrioventricular canal | A condition that is caused when the atrial and ventricular septa fail to meet, as in normal development, resulting in a low atrial and high ventricular septal defect or a common atrioventricular canal. Synonym: endocardial cushion defect. (05 Mar 2000) |
| persistent chronic hepatitis | A benign chronic hepatitis that may follow acute viral hepatitis A or B, or complicate bowel diseases; after six months, liver biopsy changes are mild, unlike active chronic hepatitis; rarely, if ever, progresses to cirrhosis, portal hypertension, or liver failure. (05 Mar 2000) |
| persistent cloaca | A condition in which the urorectal fold has failed to divide the cloaca of the embryo into rectal and urogenital portions. Synonym: sinus urogenitalis, urogenital sinus. (05 Mar 2000) |
| persistent ectopic pregnancy | An ectopic pregnancy which has persistent viable tissue, secreting hCG after conservative surgery. (05 Mar 2000) |
| persistent foetal circulation syndrome | <syndrome> A syndrome of persistent pulmonary hypertension in the newborn infant, without demonstrable cardiac disease. It is characterised by cyanosis and acidosis, severe pulmonary vasoconstriction, hypertrophy of pulmonary arterial muscle, and elevated pulmonary vascular resistance, with resultant right-to-left shunting of blood through a patent ductus arteriosus and at times a patent foramen ovale. (12 Dec 1998) |
| persistent generalised lymphadenopathy | A syndrome characterised by reactive hyperplasia of lymph nodes (of at least one month's duration and at two different body sites, not including the inguinal area) in patients infected with the human immunodeficiency virus. The lymph node lesions progress from benign reactive hyperplasia through a stage of mixed follicular hyperplasia, to follicular involution with lymphocyte depletion. Many go on to a malignant non-Hodgkin's lymphoma. (05 Mar 2000) |
| persistent mullerian duct syndrome | <syndrome> Familial disorder with presence of fallopian tube, uterus, and testis in a male. Deficient mullerian inhibitory substance secondary to Sertoli cell defect. Synonym: hernia uteri inguinale. (05 Mar 2000) |
| persistent posterior hyperplastic primary vitreous | A unilateral congenital anomaly in full-term infants; associated with a congenital retinal fold and a vitreous membranous stalk containing remnants of the hyaloid artery. (05 Mar 2000) |
| persistent tremor | A tremor that is constant, whether the subject is at rest or moving. Synonym: continuous tremor. (05 Mar 2000) |