Most common database management systems represent information in a simple record-based format. Semantic modeling provides richer data structuring capabilities for database applications. In particular, research in this area has articulated a number of constructs that provide mechanisms for representing structurally complex interrelations among data typically arising in commercial applications. In general terms, semantic modeling complements work on knowledge representation (in artificial intelligence) and on the new generation of database models based on the object-oriented paradigm of programming languages.This paper presents an in-depth discussion of semantic data modeling. It reviews the philosophical motivations of semantic models, including the need for high-level modeling abstractions and the reduction of semantic overloading of data type constructors. It then provides a tutorial introduction to the primary components of semantic models, which are the explicit representation of objects, attributes of and relationships among objects, type constructors for building complex types, ISA relationships, and derived schema components. Next, a survey of the prominent semantic models in the literature is presented. Further, since a broad area of research has developed around semantic modeling, a number of related topics based on these models are discussed, including data languages, graphical interfaces, theoretical investigations, and physical implementation strategies.
The first half of this manuscript is devoted to a review of the methods used and the results obtained in the published measurements of the normal responses to tests of the three main types of hypothalamic-pituitary-adrenocortical (HPA) activity in man. These are, I, basal, unstressed activity leading to appropriate levels of total daily production of cortisol in the characteristic circadian pattern; II, responses to feedback stimulation of HPA activity by metyrapone administration; and III, responses to tests of the effects of stress on the HPA system including the effects of hypoglycemia, induced fever, vasopressin administration, and ACTH injections and infusions. The advantages and shortcomings of each type of procedure are discussed. The second half of this paper describes the authors' attempts to establish the limits of normality of standard and modified methods of evaluating the HPA system. The defined limits of normality have been used to assess the HPA function in 158 patients with known or suspected disorders of the HPA system. In normal controls, halfhourly plasma cortisol determinations established the normality of circadian and postprandial fluctuations and of mean plasma cortisol concentration, 6.2 +/- 0.3 (SEM) micrograms/dl, which were closely approximated by determinations every 6 h. Metyrapone, given in a dose of 500 mg every 2 h for 24 h increased urinary 17-OHCS excretion to 10.5-32.6 mg/day or to 1.7-7.8 times basal excretion rate. Increasing rates of insulin infusion disclosed significant relationships between resulting plasma glucose and cortisol concentrations. The slopes of the delta cortisol/delta glucose responses were similar after insulin infusions (0.46 +/- 0.05) and after insulin injections, 0.15 U/kg (0.43 +/- 0.09), and were always greater than 0.20 micrograms/mg. This index provides a useful objective measure of the normality of responses to hypoglycemic stress, 0.20-0.87 micrograms/mg. Adrenocortical responses to iv infusions of ACTH (cosyntropin 0.25 mg) may be equivocal at 2 h but are clear cut at 4, 6 and 8 h. Of 158 patients in whom hypopituitarism was known or suspected because of the presence of a pituitary tumor, acromegaly, hyperprolactinemia, or clinical features, HPA function was found to be entirely normal in 88 patients and partially or severely abnormal in the remaining 70 patients.(ABSTRACT TRUNCATED AT 400 WORDS)
N e w Y o r kIt has been established by phylogenetic, ontogenetic and cyto-architectural studies that the spinal trigeminal nucleus in primates and higher vertebrate forms is composed of three distinct cell groups (Olszewski, '50; Crosby and Yoss, '54; Brown, '56, '58). These three nuclear groups are arranged within the spinal trigeminal nucleus in a caudo-cephalad Iashion. Nucleus caudalis is the most caudal and extends rostrally to the level of the obex where it is continuous with the lower pole of the nucleus interpolaris. The cephalad margin of the nucleus interpolaris blends into the nucleus oralis at the level of the upper pole of the hypoglossal nucleus. The nucleus oralis extends rostrally to the level of the trigeminal main sensory nucleus.The nucleus caudalis, which first appears in cyclostomes (Crosby and Yoss, '54), is the most primitive cell group of the spinal trigeminal nuclear complex. It is also the first cell group to differentiate during the course of the development of the spinal trigeminal nuclear complex in the fetus (Brown, '58). Cajal (1895), Gerard ('23) and Olszewski ( ' 5 0 ) , among others, have noted the similar cyto-architecture of the apical gray substance of the dorsal horn of the spinal cord and the nucleus caudalis and have described the nucleus caudalis as a prolongation of this region into the medulla. The nucleus caudalis is composed of three distinct cellular regions (Olszewski, '50) which are subnucleus zonalis, subnucleus gelatinosus and subnucleus magnocellularis. The subnucleus zonalis corresponds to the posteromarginal nucleus whereas the subnuclei gelatinosus and magnocellularis are analogous to the substantia gelatinosa and nucleus proprius, respectively, of the spinal cord dorsal horn.Descriptions of the secondary fiber projections emanating from the spinal trigeminal nucleus in both m a n and animals have been reported by numerous authors. Early studies of both man (Hosel, 1892; Spitzer, 1899) and animals (Wallenberg, 1896; van Gehuchten, '01) indicate that secondary axons cross to the contralateral medulla before turning cephalad and ascending to the thalamus. Cajal (1895, '04) described fiber projections which were present in the reticular formation and medial lemniscus of each side. Other investigators who have described contralateral ascending projections are Clark ('36), Woodburne ('36), Smyth ('39) and Walker ('39, '42). More recently Nauta and Kuypers ('58) have described bilateral ascending fiber degeneration following lesions which involved all of the spinal trigeminal nucleus, whereas Carpenter and Hanna ('61) found only contralateral ascending fiber projections to the thalamus in cats which had lesions placed in only the nucleus interpolaris and nucleus oralis of the spinal trigeminal nucleus.On the basis of these studies, the efferent pathways arising in the spinal trigeminal nucleus may be subdivided into four groups : ( 1 ) Bilateral, but predominantly crossed, ascending fiber tracts to the midbrain and thalamus; ( 2 ) Secondary axons to the XIIth, XIt...
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