| 1. |
- Bergstrom, H, et al.
(författare)
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Two different types of hollow-cathode discharges used for high resolution laser spectroscopy on copper
- 1989
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Ingår i: Zeitschrift für Physik D Atoms, Molecules and Clusters. - 0178-7683. ; 13:3, s. 203-206
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Tidskriftsartikel (refereegranskat)abstract
- Two different techniques, Doppler-free saturation spectroscopy on a hollow-cathode discharge and fluorescence spectroscopy on a collimated atomic beam produced from a hollow-cathode discharge, have been used for high-resolution laser-spectroscopy measurements on the 3d10 4p and 5p states in neutral Copper. The relative merits of the two techniques are discussed.
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| 2. |
- Bicsak, T A, et al.
(författare)
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Tissue-type plasminogen activator in rat oocytes : expression during the periovulatory period, after fertilization, and during follicular atresia.
- 1989
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Ingår i: Endocrinology. - 0013-7227 .- 1945-7170. ; 124:1, s. 187-94
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Tidskriftsartikel (refereegranskat)abstract
- The regulation of tissue-type plasminogen activator (tPA) in rat oocytes during the periovulatory period, in early embryos, and in oocytes during induced follicular atresia was studied using a quantitative chromogenic substrate assay. Oocytes and early embryos were collected from three ovulation models: 1) intact immature female rats treated with PMSG, followed by hCG 48 h later; 2) hypophysectomized immature rats treated with PMSG, followed by a GnRH agonist (GnRHa) 56 h later; and 3) adult cyclic rats on the mornings of proestrus and estrus and up to 5 days after fertilization. In addition, follicular atresia was induced by either withdrawal of diethylstilbestrol (DES) for 2 days or injection of GnRHa for 2 days in hypophysectomized DES-implanted immature rats. Treatment with PMSG alone did not increase oocyte tPA content (5-20 microIU/oocyte) in either immature rat model, but treatment with either hCG or GnRHa induced meiotic maturation and ovulation and increased tPA activity to 80 and 140 microIU/oocyte 24 h after hCG and GnRHa treatment, respectively. Northern blot analysis of total RNA extracted from oocytes of PMSG-treated rats indicated the presence of a specific tPA message at 22S. tPA levels were low in preovulatory oocytes obtained on proestrus morning and increased in ovulated oocytes on estrus morning. After fertilization, tPA levels remained high in the embryos on days 1-4 of pregnancy, but dropped dramatically on day 5. Furthermore, oocytes from atretic follicles of hypophysectomized DES-implanted rats after either DES withdrawal or GnRHa treatment contained elevated levels of tPA, coincident with germinal vesicle breakdown (GVBD). Immunohistochemical staining revealed tPA antigen only in those oocytes that had undergone apparent meiotic maturation, as confirmed by GVBD. Thus, oocytes contain tPA mRNA and synthesize the active protease under a variety of stimuli which result in GVBD. The observed periovulatory increase in oocyte tPA activity, its maintenance until day 5 of pregnancy, and expression of tPA in nonovulatory oocytes of atretic follicles suggest diverse functions for the oocyte and embryo tPA.
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| 3. |
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| 5. |
- Hsueh, A J, et al.
(författare)
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Gonadotropin-releasing hormone induces ovulation in hypophysectomized rats : studies on ovarian tissue-type plasminogen activator activity, messenger ribonucleic acid content, and cellular localization.
- 1988
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Ingår i: Endocrinology. - 0013-7227 .- 1945-7170. ; 122:4, s. 1486-95
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Tidskriftsartikel (refereegranskat)abstract
- GnRH and its agonists are known to induce ovulation in hypophysectomized rats by acting directly at the ovary. Because tissue-type plasminogen activator (tPA) has been implicated in the gonadotropin induction of ovulation, we examined the effect of an ovulatory dose of GnRH on ovarian tPA activity, mRNA content, and cellular localization. Hypophysectomized immature rats were injected sc with 20 IU PMSG and a single dose of a GnRH agonist (GnRHa; des-Gly10,DLeu6(N alpha Me)Leu7,Pro9NHEt-GnRH) 58 h later. At different times after treatment, ovaries were prepared for morphological analysis. Using a fibrin overlay method, tPA activities were measured in ovarian homogenates and cumulus-oocyte complexes, whereas granulosa cells were cultured for 24 h to estimate tPA secretion. Total ovarian RNA was prepared for hybridization analysis of tPA message levels, and tPA localization was studied by immunohistochemistry of ovarian sections. GnRHa induced ovulation in PMSG-primed hypophysectomized rats 14-16 h after injection in a dose-dependent manner, and the GnRHa action was blocked by concomitant treatment with a GnRH antagonist. GnRHa stimulated the induction of tPA, but not urokinase-type PA, activity in ovarian homogenates and granulosa cell-conditioned medium in a time-dependent manner, reaching a maximum before ovulation. tPA activity in cumulus-oocyte complexes was also increased before ovulation, but this increase was sustained. Hybridization analysis of steady state tPA mRNA levels was performed using a rat cRNA probe. Northern blot analysis of total ovarian RNA demonstrated that GnRHa stimulated tPA mRNA levels 12 h after treatment, with a subsequent decrease 24 h after treatment. Immunohistochemistry indicated substantial increases in tPA staining in granulosa cells and oocytes of preovulatory follicles before ovulation. Thus, GnRHa acts through specific receptors to increase ovarian tPA enzyme activity, mRNA content, as well as immunostaining in granulosa cells and oocytes. Like gonadotropins, GnRH may induce ovulation by directly stimulating tPA levels in the ovary.
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| 6. |
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| 7. |
- Peng, Zebo, 1958-
(författare)
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Steps towards the formalization of designing VLSI systems
- 1985
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes an attempt to formalize the design process of VLSI systems as a sequence of semantics-preserving mappings which transforms a program-like behavioral description into a structural description. The produced structural description may then be partitioned into several potential asynchronous modules with well-defined interfaces. The proposed strategy is based on a formal computational model derived from timed Petri net and consisting of separate, but related, models of control and data parts. Partitioning of systems into submodules is provided both on the data part and on the control part, which produces a set of pairs of corresponding data subparts and control subparts and allows potential asynchronous operation of the designed systems as well as physical distribution of the modules. The use of such a formal specification also leads to the effective use of CAD and automatic tools in the synthesis process as well as providing for the possibility of verifying some aspects of a design before it is completed. CAMAD, an integrated design aid system, has been partially developed based on these formalizations. The present thesis attempts also to formulate the control/data path allocation and module partitioning problem as an optimization problem. This differs from previous approaches where ad hoc algorithms and predefined implementation structures are explicitly or implicitly used, and where a centralized control strategy is assumed.
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