Showing papers by "Lund University published in 1980"

A Comparison of the Super-CI and the Newton-Raphson Scheme in the Complete Active Space SCF Method

Abstract: A density matrix formulation is presented of the super-C I and Newton-Raphson methods in complete active space SCF (CASSCF) calculations. The CASSCF method is a special form of the MC-SCF method, where the C I wave function is assumed to be complete in a subset of the orbital space (the active space), leaving the remaining orbitals doubly occupied in all configurations. Explicit formulas are given for all matrix elements in the super-C I method and the first and second derivatives in the Newton-Raphson formulation. The similarities between the two methods are pointed out and the differences in the detailed formulations are discussed. Especially interesting is the fact, that while the second derivatives can be expressed in terms of first and second order density matrices, the matrix elements between the super-C I states involve also the third order density matrix in some cases.

The Human Experience of Space and Place

Abstract: Phenomenology strives for the actualization of contact. As a way of study it seeks to meet the things of the world as those things are in themselves and so describe them. Geography studies the earth as the dwelling place of man. As one of its tasks, it seeks to understand how people live in relation to everyday places, spaces, and environments. A phenomenological geography borrows from both fields of knowing and directs its attention to the essential nature of man’s dwelling on earth. The fact that all people are located in a world which is in part geograph­ ical is an irreducible characteristic of human existence. Be it small as an apartment or expansive as the ocean surrounding his ship at sea, as commonplace as a neighborhood or as strange as a distant country, man is housed in a geographical world whose specifics he can change but whose surrounds in some form he can in no way avoid. A phenomen­ ological geography asks the significance of people’s inescapable immer­ sion in a geographical world. What are people as beings in a geographical world? What is the nature of human experience in the context of that world? (Less)

Evolution of Clutch Size in Birds: Adaptive Variation in Relation to Territory Quality

Abstract: Reproductive output from enlarged or reduced magpie broods showed that each female generally lays a clutch of optimal size This size varies considerably between females Approximately 85 percent of the within-years variation in clutch size was associated with differences between territories Colonial bird species, lacking individual foraging territories, have a smaller clutch size variation than territorial species

Self-Tuning Controllers Based on Pole-Zero Placement

Abstract: The paper gives a review of pole-placement design for systems with known parameters, then focuses entirely on the servos. Adaptive pole-placement algorithms are discussed, leading to the formulation of explicit and implicit schemes, and simulation of the behaviour of the alorithms is given.

Zeros of sampled systems

Abstract: The zeros of the discrete time system obtained when sampling a continuous time system are explored. Theorems for the limiting zeros for large and small sampling periods are given. A condition which guarantees that the sampled system only has stable zeros is also presented.

Peroxidative Changes in Brain Cortical Fatty Acids and Phospholipids, as Characterized During Fe2+- and Ascorbic Acid-Stimulated Lipid Peroxidation In Vitro

Abstract: The occurrence of peroxidative damage, as distinguished from anaerobic damage, to brain fatty acids and phospholipids was characterized in vitro. Fe2+ and ascorbic acid were used to stimulate peroxidation in cortical homogenates from rat brain incubated with or without oxygen. Lipid peroxidation was established in samples incubated with oxygen by increased diene conjugation, accumulation of thiobarbituric acid-reactive material (TBAR) and of lipid-soluble fluorescent products. No peroxidation occurred in samples incubated in the absence of oxygen (100% N2). Lipid peroxidation was characterized by a selective loss of arachidonic acid and docosahexaenoic acid and by degradation of ethanolamine phosphoglyceride, while choline phosphoglyceride did not change. During the course of peroxidation there were parallel increases in products of lipid peroxidation concomitant with the decrease in polyenoic fatty acids. The maximal changes in diene conjugation and TBAR occurred earlier than the maximal changes in fluorescent material and fatty acids. It is concluded that measurements of changes in brain fatty acid and phospholipid composition may be a useful tool to establishment of whether peroxidative damage is important in vivo in situations with a critically reduced oxygen supply. Estimation of lipid-soluble fluorescence in vivo may also be useful, since it is considered to reflect the accumulation of stable end products of peroxidation.

Skeletal stages of the hand and wrist as indicators of the pubertal growth spurt

Abstract: Longitudinal data on adolescent growth in height and skeletal development of the hand and wrist were collected as part of a prospective study of the growth and development of 212 randomly selected Swedish urban children. The onset, peak and end of the pubertal growth spurt were defined on the unsmoothed incremental curve of height. The skeletal development was evaluated by studying the attainment of specified stages of the ulnar sesamoid of the metacarpophalangeal joint of the first finger, the epiphyses of the middle and distal phalanges of the third finger and the distal epihysis of the radius. All growth events and skeletal stages occurred earlier in girls than in boys. At the peak of the pubertal growth spurt the skeletal development was more advanced in girls than in boys, but at the end of the spurt the girls had a less mature skeletal development than the boys. The analysis of the relationship in time between the growth events and the skeletal stages showed that these stages can be used to indicate which period of adolescent growth an individual has reached.

Functional reinnervation of the neostriatum in the adult rat by use of intraparenchymal grafting of dissociated cell suspensions from the substantia nigra.

Abstract: Dissociated cell suspensions were prepared from the substantia nigra of 15–17 day-old rat embryos and grafted via an intraparenchymal injection into the depth of the neostriatum of adult recipient rats. The survival and fibre outgrowth of the dopamine-containing neurones in the implants were studied by fluorescence histochemistry, and the functional capacity of the grafts was monitored by repeated testing of the amphetamine-induced turning behaviour of the implanted rats.

Barrier mechanisms for neurotransmitter monoamines and their precursors at the blood‐brain interface

Abstract: The integrity of the endothelial cell lining of the cerebrovascular bed constitutes a morphological blood-brain barrier mechanism to neurotransmitter monoamines. Circulating monoamines are prevented from entering the brain primarily at the luminal membrane of the endothelial lining. The small percentage of amines that may pass this membrane is deaminated within the endothelial cells and pericytes of brain microvessels (capillaries, venules, and small veins) and, in the case of large parenchymal and pial vessels, in the smooth muscle layers, where Omethylation also takes place. In the choroid plexus a corresponding deamination and O-methylation takes place in the epithelial cells. The presence of these enzymes constitutes a further, enzymatic, blood-brain barrier in the brain vessels for these monoamines. The monoamine precursors L-3,4-dihydroxyphenylalanine (L-dopa) and L-5-hydroxytryptophan readily pass from the luminal endothelial cell membrane but are trapped by another enzymatic barrier mechanism. Within the endothelial cells and pericytes of the microvasculature, these compounds are decarboxylated to their corresponding amines and then immediately deaminated. One clinical implication of these enzymatic barrier mechanisms is the use of decarboxylase and monoamine oxidase inhibitors as adjuncts to L-dopa treatment of Parkinson disease; these substances facilitate the entry of L-dopa into brain and thus increase the amount of dopamine available at receptor sites. A brief hypertensive or hypertonic stimulus can transiently open the blood-brain barrier through an effect on endothelial cell linings. High circulating concentrations of monoamines can also open the morphological barrier, but probably only indirectly by inducing an acute rise in systemic blood pressure. Once the barrier is open, systemically administered monoamines enter the brain parenchyma, where they can induce pronounced changes in cerebral blood flow and metabolism.

Origin and distribution of VIP (vasoactive intestinal polypeptide)-nerves in the genito-urinary tract.

Abstract: VIP (Vasoactive Intestinal Polypeptide)-immunoreactive nerves were found throughout the genito-urinary tract of the cat; they were less numerous in the guinea pig and in the rat. In the cat, VIP nerves were particularly numerous in the neck of the urinary bladder and proximal urethra, in the uterine cervix and in the prostate gland. The nerves were found in smooth muscle, around blood vessels and in the connective tissue immediately beneath the epithelium. Ganglia were found below the trigonum area of the bladder, in the wall of the proximal urethra, and in paracervical tissue. VIP-immunoreactive nerve cell bodies occurred in all these ganglionic formations. These ganglia probably represent the origin of the VIP nerves of the genital tract since their removal in the female cat greatly reduced the VIP nerve supply. Transection of the hypogastric nerves had no overt effect. Transection of the cervix eliminated the VIP nerves above the level of the lesion, except those in the ovaries, supporting the view that the VIP nerves of the uterus and the oviduct are derived from a paracervical source.

Effect of Water Content on the Gelatinization of Wheat Starch

Abstract: The influence of water content on the gelatinization of wheat starch was examined by differential scanning calorimetry. Three endothermic transitions were observed when starch was heated to 140 °C with 35 to 80% (w/w) water. The temperature of the second and third endotherms and the enthalpies of the first and second endotherms vary with water content.

Influence of complete and pronounced incomplete cerebral ischemia and subsequent recirculation on cortical concentrations of oxidized and reduced glutathione in the rat.

Abstract: The influence of complete and pronounced incomplete cerebral ischemia on cortical concentrations of reduced (GSH) and oxidized (GSSG) glutathione was studied in lightly anaesthetized (70% N2 O) rats. GSH was extracted with HCl-methanol-perchloric acid and GSSG with trichloroacetic acid in the presence of N-ethylmaleimide and measured fluorometrically, giving normal concentrations in cortical tissue of about 2 and 0.01 μmol.g−1 respectively. Reversible complete ischemia was induced by increasing the intracranial pressure to above the systolic blood pressure by infusing mock CSF into the cisterna magna. Reversible pronounced incomplete ischemia was induced by bilateral carotid artery clamping combined with hypovolemic hypotension. Whether complete or incomplete, a 30-min ischemic period caused a similar decrease in cortical GSH concentration (to about 90% of control) without any concomitant accumulation of GSSG in the tissue (or in CSF). Prolongation of the ischemic period (complete ischemia) to maximally 120 min caused an almost linear decrease of the tissue glutathione concentration to 45% of the preischemic value. During subsequent recirculation following a 30 min period of either complete or pronounced incomplete ischemia, there was a further decrease in cortical GSH concentrations without a reciprocal increase in GSSG concentrations. Lipid peroxidation (verified by determination of malondialdehyde production) induced in brain cortical tissue in vitro caused oxidation of tissue GSH with accumulation of GSSG. As the observed decrease in GSH during brain ischemia in vivo was not accompanied by any reciprocal increase in GSSG the results fail to support the hypothesis that peroxidative damage occurs during or following brain ischemia. The finding of an unchanged GSSG concentration does, however, not exclude the possibility of an increased turnover rate in the glutathione reductase reaction. It is concluded that the observed decrease in tissue GSH concentration mainly reflects a decrease in the glutathione pool size, due to an imbalance between breakdown and synthesis secondary to tissue energy failure.

Treatment of premature labor with the calcium antagonist nifedipine.

Abstract: The effect of the calcium antagonist nifedipine on premature labor was investigated in ten carefully selected patients. The main aim of treatment was to inhibit uterine activity and delivery for 3 days during which time fetal lung maturation was accelerated by glucocorticoid treatment. In all 10 patients, uterine activity was abolished during the 3 days of treatment and delivery was also postponed. No serious maternal side effects were observed. All children were delivered in good condition. All survived and were alive and well at 1 year.

VIP (vasoactive intestinal polypeptide)-containing nerves of intracranial arteries in mammals.

Abstract: Immunohistochemical and radioimmunochemical investigations have shown, in various species, the occurrence of numerous nerve fibres containing vasoactive intestinal polypeptide (VIP) in connection with blood vessels of the central nervous system. Pial arteries from pig, cat, and rat have the richest supply of VIP nerve fibres; those of cow, dog, guinea pig and hamster have an intermediary number of nerves, while only few are found in pial arteries from the monkey, rabbit, gerbil, and mouse. The regional variation in VIP-nerve density follows the order: cerebral arteries > cerebellar arteries > basilar > vertebral > spinal cord arteries. Unilateral extirpation of either the pterygopalatine or the superior cervical ganglia does not affect the amount or distribution of VIP fibres in the wall of brain vessels of the ipsilateral side. Measurement of the VIP content by radioimmunoassay shows mean concentrations in the pial arteries varying between 19 and 82 pmol/g tissue wet weight. Regional and species variations in measured VIP levels are similar to the variations in distribution of immunoreactive nerve fibres.

Characterization ofYersinia enterocolitica sensu stricto

Abstract: The speciesYersinia enterocolitica is definedsensu stricto on the bases of biochemical and other phenotypic characteristics. Biochemically,Y. enterocolitica contains five major biotypes: 1 through 4 of Nilehn and of Wauters, and the trehalose-negative, metabolically inactive, socalled hare strains in biotype 5 of Nilehn and of Wauters, and biochemically atypical strains, including urease-negative, Simmons' citrate-positive, and lactose-and raffinose-positive strains.Y. enterocolitica sensu stricto was distinguishable from the newly described speciesYersinia kristensenii by sucrose and Voges-Proskauer reactions (negative inY. kristensenii). These species were previously separated by DNA relatedness.Y. enterocolitica was also separable biochemically and by DNA relatedness from the two newly proposed rhamnose-positive species,Yersinia intermedia andYersinia frederiksenii. Strain 161(=CIP 80-27=ATCC 9610) is proposed as the neotype forY. enterocolitica.

Yersinia frederiksenii: A new species of enterobacteriaceae composed of rhamnose-positive strains (formerly called atypicalyersinia enterocolitica orYersinia enterocolitica-Like)

Abstract: Yersinia frederiksenii sp. nov. is defined biochemically and genetically.Y. frederiksenii stains belong to three separate DNA relatedness groups, each of which is separable fromY. enterocolitica, Y. intermedia, Y. kristensenii, Y. pseudotuberculosis, andYersinia biotypes X1 and X2. The threeY. frederiksenii DNA relatedness groups, 6175, 2581-77, and 867, were represected by 10, 3, and 1 strain, respectively. All three groups were phenotypically similar. Pending additional study, it was decided to retain them all inY. frederiksenii. The positive rhamnose reaction separatesY. frederiksenii fromY. enterocolitica, Y. kristensenii, andYersinia biotype X1. A positive sucrose reaction distinguishesY. frederiksenii from the rhamnose-positive, sucrose-negativeYersinia biotype X2. Negative reactions for melibiose, raffinose, and α-methyl-d-glucoside distinguishY. frederiksenii fromY. intermedia. A negative melibiose reaction and positive reactions for ornithine decarboxylase, indole, sucrose, sorbose, sorbitol, inositol, and Voges-Proskauer separateY. frederiksenii fromY. pseudotuberculosis. Strain 6175 (=CIP 80-29) is proposed as the type strain forY. frederiksenii.