Showing papers by "University of Southern Denmark published in 1998"

Biodemographic Trajectories of Longevity

Abstract: Old-age survival has increased substantially since 1950 Death rates decelerate with age for insects, worms, and yeast, as well as humans This evidence of extended postreproductive survival is puzzling Three biodemographic insights—concerning the correlation of death rates across age, individual differences in survival chances, and induced alterations in age patterns of fertility and mortality—offer clues and suggest research on the failure of complicated systems, on new demographic equations for evolutionary theory, and on fertility-longevity interactions Nongenetic changes account for increases in human life-spans to date Explication of these causes and the genetic license for extended survival, as well as discovery of genes and other survival attributes affecting longevity, will lead to even longer lives

A Novel Class of Oligonucleotide Analogues Containing 2'-O,3'-C-Linked [3.2.0]Bicyclo-arabinonucleoside Monomers: Synthesis, Thermal Affinity Studies and Molecular Modelling

Abstract: Oligonucleotide analogues containing a novel 2‘-O,3‘-C-linked [3.2.0]bicyclonucleoside have been efficiently synthesized. Enhanced thermal stabilities of duplexes toward both RNA and DNA are report...

A history of European women's work

Abstract: The work patterns of European women from 1700 onwards fluctuate in relation to ideological, demographic, economic and familial changes. In A History of European Women's Work, Deborah Simonton draws together recent research and methodological developments to take an overview of trends in women's work across Europe from the so-called pre-industrial period to the present. Taking the role of gender and class in defining women's labour as a central theme, Deborah Simonton compares and contrasts the pace of change between European countries, distinguishing between Europe-wide issues and local developments.

Ties between Center and Periphery in the Scientific World-System: Accumulation of Rewards, Dominance and Self-Reliance in the Center

Abstract: This study accounts for the organization of scientific research in networks of socio-intellectual tices that bind scientists into a community cultivating the scientific tradition. During the twentieth century the scientific community has become incrcasingly global both in the sense that its membership has spread world-widely and in the sense that its long-distance ties have intensified. The globalization of the community and its ties has been promoted by widely institutionalized arrangements, especially through the world's adoption of and belief in several scientific tenets: the universal validity of scientific knowledge, the ownership principle that knowledge should be the common property of humankind, and the political principle of granting autonomy to scientists for forming ties. The community and its network of ties form a hierarchy with centers attracting ties from peripheries. During the twentieth century the main center has shifted from Western Europe to North America while Eastern Europe has become less central, East Asia has become a bit central, and other regions have remained peripheral. A center attracts students from around the world for education, attracts scientists for conferences and visits, attracts deference from scientists throughout the world, exerts pervasive influence, is widely emulated, and is a desired source of recognition . In the global networks of ties, specifically of deference, influence, emulation and desire for recognition, there is an accumulation in the center of ties, both from within the center as an enhanced self-reliance and from the periphery as an enhanced centrality, exceeding the research performance at the center.

The stereoselective metabolism of fluoxetine in poor and extensive metabolizers of sparteine

Abstract: The selective serotonin reuptake inhibitor fluoxetine is administered as a racemic mixture, and R- and S-fluoxetine are metabolized in the liver by N-demethylation to R- and S-norfluoxetine, respectively. R- and S-fluoxetine and S-norfluoxetine are equally potent selective serotonin reuptake inhibitors, but R-norfluoxetine is 20-fold less potent in this regard. Racemic fluoxetine and norfluoxetine are potent inhibitors of cytochrome P450 (CYP) 2D6 in vivo and in vitro and recent studies in vivo have shown that racemic fluoxetine is metabolized by CYP2D6. The primary aim of the present study was to investigate the stereoselective metabolism of fluoxetine and norfluoxetine by CYP2D6 in vivo. A single oral dose of fluoxetine (60 mg) was administered to six poor and six extensive metabolizers of sparteine. Blood samples were collected during 6 weeks for poor metabolizers and 3 weeks for extensive metabolizers. Once a week a sparteine test was performed. The R- and S-enantiomers of fluoxetine and norfluoxetine were determined by a stereoselective gas chromatography-mass spectroscopy method. In the poor metabolizers, the oral clearance of R- and S-fluoxetine was 3.0 l/h and 17 l/h, respectively, the corresponding values in the extensive metabolizers were 36 l/h and 40 l/h, respectively. For both enantiomers, the phenotype difference was statistically significant. In poor metabolizers, the elimination half-lives were 6.9 days and 17.4 days for R- and S-norfluoxetine, respectively, and in the extensive metabolizers it was 5.5 days for both enantiomers, a significant phenotypical difference only for S-norfluoxetine. For fluoxetine the elimination half-lives were 9.5 and 6.1 days in poor metabolizers for the R- and S-enantiomer, respectively. The corresponding values in the extensive metabolizers were 2.6 and 1.1 days, respectively. Also for this parameter, the differences were statistically significant. This study shows that CYP2D6 catalyses the metabolism of R- and S-fluoxetine and most likely the further metabolism of S-norfluoxetine but not of R-norfluoxetine.

Computing Limit Loads by Minimizing a Sum of Norms

Abstract: This paper treats the problem of computing the collapse state in limit analysis for a solid with a quadratic yield condition, such as, for example, the von Mises condition. After discretization with the finite element method, using divergence-free elements for the plastic flow, the kinematic formulation reduces to the problem of minimizing a sum of Euclidean vector norms, subject to a single linear constraint. This is a nonsmooth minimization problem, since many of the norms in the sum may vanish at the optimal point. Recently an efficient solution algorithm has been developed for this particular convex optimization problem in large sparse form. The approach is applied to test problems in limit analysis in two different plane models: plane strain and plates. In the first case more than 80% of the terms in the objective function are zero in the optimal solution, causing extreme ill conditioning. In the second case all terms are nonzero. In both cases the method works very well, and problems are solved which are larger by at least an order of magnitude than previously reported. The relative accuracy for the solution of the discrete problems, measured by duality gap and feasibility, is typically of the order 10-8.

Cytogenetic comparison of primary tumors and lymph node metastases in breast cancer patients

Abstract: Chromosome banding analysis of primary tumors and axillary lymph node metastases from 10 breast cancer patients revealed abnormal karyotypes in all samples with cytogenetic similarities between the primary tumor and the metastasis in all informative pairs. Although karyotypically unrelated clones were also found in the lymph node samples, they were less numerous than in the primary tumors, indicating that there was more genetic heterogeneity among the neoplastic cells in the primary than in the secondary tumors. On the other hand, some of the clones had become more complex in the metastases as a result of clonal evolution, and by and large these metastatic breast cancer cases had more karyotypic anomalies than do unselected primary breast carcinomas. Among the aberrations occurring more frequently, and that consequently may predispose to disease spread, were losses of chromosomes 17 and 22 and homogeneously staining regions, a cytogenetic sign of gene amplification. Genes Chromosomes Cancer 22:122–129, 1998. © 1998 Wiley-Liss, Inc.

Child Culture - Play Culture

Abstract: The concept Children’s Culture refers to two different types of cultural manifestation. 1. The cultural products made for children mainly by adults in different classical and medias, such as children’s literature, toys, TV and computergames. 2. Children’s oral culture and play culture produced and performed by children and transmitted within the frames of a special type of social network. This culture includes aesthetic expressions such as games, tales, songs and a variety of other activities which play an important role in children’s lives and development. The paper describes these two types of child culture and their interplay and has its focus in outlining the field and establishing a framework for the understanding of play culture, children’s lore and other symbolic aesthetic forms of expression. Child Culture Play Culture

Hydrography, near-bottom currents, and grazing impact of the filter-feeding ascidian Ciona intestinalis in a Danish fjord

Abstract: Grazing exerted by a bed of filter-feeding ascidians, Ciona intestinalis, was examined in Kertinge Nor, the innermost shallow cove of a Danish fjord connected to the Great Belt. The aim was to study the dynamic interactions between the water column and benthic Filter feeders in order to account for the variability of phytoplankton biomass seen in the fjord. The moderate tidal- and density-driven near-bottom currents were both estimated and directly measured by means of an underwater video technique, and the downstream reduction in algal concentration over the ascidian bed documented and mathematically modelled. Relatively high algal concentrations developing in the surface layers during stratification may only be available to benthic grazers if a density-driven circulation, due to a salinity change in the Great Belt, carries these algae down to the bottom. Though wind is a crucial force for vertical mixing and transport of phytoplankton to the bottom, the frequent salinity changes in the Danish s...

Chromosome banding analysis of gynecomastias and breast carcinomas in men

Abstract: Male breast cancer is 100 times less frequent than its female counterpart and accounts for less than 1% of all cancers in men. Although men with breast cancer also often have gynecomastia, it is still unknown whether gynecomastia per se predisposes the male breast to malignant disease. We describe the cytogenetic analysis of three gynecomastias and four breast cancers in men. No chromosome abnormalities were detected in two cases of gynecomastia, with no other concomitant breast disease. The third gynecomastia sample, taken from a site where a breast carcinoma had previously been removed, had a t(2;11)(p24;p13) as the sole chromosome change; this is the first time that an abnormal karyotype has been described in gynecomastia. All four cancers had clonal chromosome abnormalities. Several cytogenetically unrelated clones were found in the breast tumor and in a metastasis from case 1. In the carcinoma of case 2, a single abnormal clone was found, characterized by loss of the Y chromosome, monosomy 17, and a deletion of the long arm of chromosome 18. In the carcinoma of case 3, a clone with loss of the Y chromosome as the sole change dominated, accompanied by the gain of an X chromosome in a subclone. In the lymph node metastasis examined from case 4, a single clone carrying trisomies for chromosomes 5 and 16 was detected. Our findings, especially when collated with data on the six karyotypically abnormal breast carcinomas in men described previously, indicate that gain of the X chromosome, gain of chromosome 5, loss of the Y chromosome, loss of chromosome 17, and del(18)(q21) are nonrandom abnormalities in male breast carcinomas. Genes Chromosomes Cancer 23:16–20, 1998. © 1998 Wiley-Liss, Inc.

Diet and blood coagulation factor VII—a key protein in arterial thrombosis

Abstract: The haemostatic system is essential for the preservation of life. The haemostatic system protects man from exsanguination after wound injuries and also forms the basis for the numerous tissue repair processes that are believed to be constantly ongoing within the vascular bed as initially proposed by Tage Astrup more than four decades ago (Astrup, 1956). The haemostatic system contributes to atherogenesis and controls intravascular thrombus formation, and thus plays an important role in the development of coronary heart disease (CHD), notably acute ischaemic events (myocardial infarction, unstable angina pectoris, and sudden death), and ischaemic stroke (Fuster et al, 1992a, 1992b; Falk & FernaÂndez-Ortiz, 1995). These diseases are dominant causes of death in industrialised countries. Accordingly, it is of utmost interest to gain insight into the haemostatic system and its possible modi®cation by internal and external factors. Such knowledge could pave the way for rational prevention of cardioand cerebrovascular disease. The present review describes how diet affects one key protein of the haemostatic systemÐ blood coagulation factor VII (FVII)Ðand also discusses the possible mechanisms underlying the dietary control of FVII. The impact of diet on FVII and other important haemostatic factors has been discussed in several other recent reviews to which interested readers are referred for additional reading (Marckmann & Jespersen, 1994, 1996; Marckmann, 1995; Mennen et al, 1996; Miller, 1996; Vorster et al, 1997; Yahia & Sanders, 1997).

Allelic imbalance and cytogenetic deletion of 1p in colorectal adenomas: a target region identified between DIS199 and DIS234.

Abstract: Both cytogenetic and molecular genetic analyses have shown that many colorectal adenomas carry an acquired deletion distally in the short arm of one chromosome 1, but the two methods have never been brought to bear on the same tumors. The major part of this study was the analysis of 53 previously short-term cultured and karyotyped colorectal adenomas for allelic imbalance at eight microsatellite loci in 1p. Allelic imbalances were detected in seven of the 12 adenomas that had cytogenetically visible abnormalities of chromosome 1, as well as in four adenomas that either had a normal karyotype (one case) or had clonal chromosome abnormalities that did not seem to involve chromosome 1 (three cases); i.e., 30% of the adenomas had abnormalities involving 1p by the combined approach. A minimal region of overlap seemed to map to between D1S199 and D1S234, suggesting that this is a relevant target region. This genomic area contains the human homologue of the tumor modifier gene Mom1 (1p35–36.1), which, in mice, modifies the number of intestinal tumors in multiple intestinal neoplasia (Min)-mutated animals. To evaluate whether the imbalances corresponded to interstitial deletions of 1p material, we performed fluorescence in situ hybridization with a pericentromeric probe (15 adenomas) and a telomeric probe (6 adenomas) on uncultured cells from the 16 adenomas with chromosome 1 abnormalities. Except for three adenomas that had already been shown by banding analysis to have a trisomic pattern, two centromere 1 signals were invariably found. In the cases hybridized with the 1p-telomeric probe, we found the same frequencies of telomeric and centromeric signals, in agreement with the interpretation that the deletions were interstitial. One of the 53 adenomas had genomic instability, seen as new alleles at five of eight microsatellite loci. A comparison of the genetic findings with clinicopathologic data indicated that adenomas in the rectum have 1p abnormalities more often than do adenomas of the sigmoid colon, and that adenomas with 1p changes are larger than adenomas without abnormalities of chromosome 1. Genes Chromosomes Cancer 21:185–194, 1998. © 1998 Wiley-Liss, Inc.

Synthesis of a criss-cross overlapped tetrathiafulvalenophane and a topologically new [2]catenane

Abstract: Using stepwise cyclization reactions followed by an intramolecular coupling, the criss-cross overlapped tetrathiafulvalenophane 8 was readily prepared. The structure of the cis,cis isomer was elucidated by X-ray crystallography which revealed a host–guest complex with chloroform. This electron donor was used for the synthesis of a topologically new type of [2]catenane 11-4PF6, under ultra-high pressure (10 kbar).

Assessing National Stereotypes in Language Attitude Studies: The Case of Class-consciousness in Denmark

Abstract: In the literature on national cultures and cross-cultural communication, Denmark and Great Britain are frequently presented as bipolar opposites in terms of social-class distinctions and class-consciousness. Britain is referred to as a class-ridden society where the stigma of a non-standard accent is devastating; Denmark is presented as a country in which social-class distinctions are virtually non-existent. This paper presents results from a language attitude study in Denmark arguing that the views presented in the literature are often popular conceptions, or expressions of political correctness, which appear to have very little in common with people's private uncensored stereotypes. The attitude data suggest that, in Denmark, people are quite capable of assigning social-class membership, and other personal characteristics, to members of different regional and social groups. The paper concludes that the overt stereotype of equalisation and a 'classless orientation' presented in the literature may be expl...

Ureteropelvic junction obstruction and ureteral strictures treated by simple high-pressure balloon dilation.

Abstract: The long-term results of simple high-pressure balloon dilation in the treatment of ureteropelvic junction obstruction (UPJO) and ureteral strictures were evaluated. A total of 77 consecutive patients were treated: 40 had UPJO and 37 ureteral strictures. The etiology of the obstruction included congenital UPJO, previous stones, sequelae of endoscopic and open surgery, radiotherapy, and urinary tract reconstruction. A retrograde ureteroscopic approach was used. Evaluation included clinical and radiographic examinations and renal scintigraphy with diuretic wash-out. The procedure was repeated in 21 cases. The median follow-up was 29 months. The procedure was considered successful if it left the patient asymptomatic and with improved renographic function and drainage. The overall success rate was 70%. The best results were obtained in strictures secondary to stones, with a success rate of 94%, and in strictures secondary to reconstructive and ureteroscopic surgery, with a success rate of 91%. In cong...

Edge-Connectivity Augmentation Preserving Simplicity

Abstract: Given a simple graph G=(V,E), our goal is to find a smallest set F of new edges such that G=(V,E\cup F) is k-edge-connected and simple. Recently this problem was shown to be NP-complete. In this paper we prove that if OPT_P^k$ is high enough---depending on k only---then OPT _S^k= OPT_P^k$ holds, where OPT_S^k$ (OPT_P^k$) is the size of an optimal solution of the augmentation problem with (without) the simplicity-preserving requirement, respectively. Furthermore, OPT_S^k- OPT _P^k\leq g(k) holds for a certain (quadratic) function of k. Based on these facts an algorithm is given which computes an optimal solution in time O(n4) for any fixed k. Some of these results are extended to the case of nonuniform demands as well.

Routes to chaos in the peroxidase-oxidase reaction. 2. The fat torus scenario

Abstract: Experimental studies [Hauser, M. J. B.; Olsen, L. F. J. Chem. Soc., Faraday Trans.1996, 92, 2857-2863] of the peroxidase-oxidase (PO) reaction at pH values in excess of 5.4 suggest the existence of narrow regions of complex dynamics between adjacent mixed-mode oscillations (MMOs) that occur in period-adding sequences. Previously [Hauser, M. J. B.; Olsen, L. F.; Bronnikova, T. V.; Schaffer, W. M. J. Phys. Chem. B 1997, 101, 5075-5083], it was argued that both the period-adding sequences and the transitional regions between neighboring MMOs are predictable by a detailed model of the reaction called BFSO [Bronnikova, T. V.; Fed’kina, V. R.; Schaffer, W. M.; Olsen, L. F. J. Phys. Chem. 1995, 99, 9309-9312]. In the present paper, we study the transitional regions via computer simulation. Our investigations indicate that the motion therein may be periodic, quasiperiodic, or chaotic. In greater detail, we observe a quasiperiodic route to chaos whereby period-doubled cycles give rise to doubled tori that, in turn, undergo homoclinic bifurcations to chaos. Because the latter transitions are a consequence of progressive fattening of the tori, we propose calling this scenario the “fat torus” route to chaos, and the homoclinic bifurcations “fat torus” bifurcations (FTBs). The numerical results are qualitatively consistent with the experimental findings reported to date. FTBs and the resultant period-doubled, fractal tori may provide a criterion for discriminating among alternative models of the PO reaction.

The Markov Chain Approximation Approach for Numerical Solution of Stochastic Control Problems: Experiences from Merton's Problem

Abstract: Many problems in modern financial economics involve the solution of continuous-time, continuous-state stochastic control problems. Since explicit solutions of such problems are extremely rare, efficient numerical methods are called for. The Markov chain approximation approach provides a class of methods that are simple to understand and implement. In this paper, we compare the performance of different variations of the approach on a problem with a well-known solution, namely Merton's consumption/portfolio problem. We suggest a variant of the method, which outperforms the known variants, at least when applied to this specific problem. We document that the size of the contraction parameter of the control problem is of great importance for the accuracy of the numerical results. We also demonstrate that the Richardson extrapolation technique can improce accuracy significantly.

Likelihood Ratio Test in the Correlated Gamma-Frailty Model

Abstract: The correlated gamma-frailty model is a generalization of Cox' proportional hazard model, which allows for correlation between individuals within the same group. The nonparametric maximum likelihood estimator in this model has previously been studied by Murphy (1994, 1995) and Parner (1998). Here we show that the likelihood ratio test can be performed with the cf2 distribution as asymptotic law, with the degrees of freedom f equal to the number of Euclidean parameters fixed under the hypothesis. As a side effect we also have a new proof for asymptotic normality and efficiency of the Euclidean component of the maximum likelihood parameter. Finally, we show how standard errors can be computed.

Bryozoan filter feeding in laminar wall layers : Flume experiments and computer simulation

Abstract: Alimentation par filtration des Bryozoaires dans des couches laminaires: essais au laboratoire et simulation informatique. Les trajectoires et les vitesses des particules ont ete determinees a l'aide d'enregistrements video effectues au-dessus de colonies de Bryozoaires formant une colonne unique (Celleporella hyalina, Electra pilosa, Alcyonidium hirsutum, Membranipora membranacea, Flustrellidra hispida) placee a la base d'un ecoulement laminaire dans des zones de gradient lineaire de vitesse (1-4 s -1 ). L'ecoulement laminaire simule les sous-couches visqueuses existant dans la nature le long de parois lisses. La trajectoire de particules approchant une colonne de 3 a 10 zooides est typiquement modifiee a une hauteur de 1 a 2 mm au-dessus de l'ouverture des lophophores et ceux-ci capturent les particules dans les couches situees entre 0,7 et 1,2 mm au-dessus de ce niveau. Les essais de laboratoire ont ete simules numeriquement en calculant l'ecoulement laminaire tri-dimensionel dans le cas d'une colonne de 10 zooides consideres comme des paires d'entonnoir capteur-source. Les trajectoires calculees des « particules de fluide » montrent comment la proportion de particules capturees par zooide decroit vers l'aval de l'ecoulement. Des resultats semblables ont ete obtenus en calculant les taux de concentration en aval de la colonie provenant de concentrations uniformes en amont de la colonie, et d'un nombre donne d'entonnoirs par zooide. Les trajectoires calculees des particules montrent que la proportion de section transversale d'ecoulement qui est videe de particules est equivalente a 16 fois la zone frontale d'un des lophophores simules. Les particules de fluide sont capturees dans les trajectoires situees a environ 1,3 mm au-dessus des entonnoirs. Pour un courant deux fois plus fort, la surface videe de particules est reduite a environ 7 fois la zone frontale, mais le taux de capture augmente d'environ 19%.