The site of Campu Stefanu, which is located in the valley of Taravu in the department of Corse-du-Sud, has yielded traces of occupation extending from the Mesolithic to the Iron Age. In 2008, a Mesolithic grave was discovered inside a... more
The site of Campu Stefanu, which is located in the valley of Taravu in the department of Corse-du-Sud, has yielded traces of occupation extending from the Mesolithic to the Iron Age. In 2008, a Mesolithic grave was discovered inside a natural granite rock shelter. The preservation of the bone material in this granite arena is extremely unusual. The upper level has yielded incomplete remains of several subjects with varying degrees of preservation, both in terms of bone material and articular relationships. Based on the number of skulls, three subjects were represented. The human remains were not accompanied by any archaeological remains that could provide a chronological and/or cultural attribution. In reality, this grave contains the bone remains of eight subjects, including one perinatal, two adolescents and five adults. The function of the grave appears to be complex as a result of connected assemblages, covered with dislocated parts. We must envisage a variety of processes, from deposit to consolidation, over a relatively long period, at least sufficient for the skeletonization. At the bottom of the grave, in direct contact with the rocky base, an additional individual represented by an articulated skeleton was discovered. Its unequal representation may have resulted from partial preservation rather than a specific funerary treatment. This subject was dated to the late 9th millennium BC, which would make it one of the first indications of peopling of the island. This discovery is clearly distinct from the simple graves isolated from the deposits of Araguina- Sennola at Bonifacio and Torre d’Aquila at Pietracorbara in Cap Corse, which constitute the island’s two other Mesolithic funerary structures.
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ABSTRACT The Koelbjerg individual, dated c. 8500 cal BC, represents the earliest human skeletal remains described from Scandinavia. Based on ancient DNA, strontium isotope and statistical anthropological analyses the individual’s sex,... more
ABSTRACT The Koelbjerg individual, dated c. 8500 cal BC, represents the earliest human skeletal remains described from Scandinavia. Based on ancient DNA, strontium isotope and statistical anthropological analyses the individual’s sex, haplogroup and geographical provenance are here analysed and discussed. In contrast to previous claims, our genetic and anthropological analyses show that this individual was a male. Additionally, the strontium isotope ratio of one of his first molars indicates that he most likely grew up locally.
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Cognitive impairment has been associated with increased mortality. Most studies, however, have only included small numbers, if at all, of the very old. In a large nationwide survey of all Danes born in 1905 and still alive in 1998, where... more
Cognitive impairment has been associated with increased mortality. Most studies, however, have only included small numbers, if at all, of the very old. In a large nationwide survey of all Danes born in 1905 and still alive in 1998, where the baseline examination was conducted, we examined the impact of cognitive impairment on mortality over a 2-year period. No cognitive impairment was defined as a score of 24-30 points on the Mini Mental State Examination, mild cognitive impairment was defined as a score of 18-23 points, and severe impairment was defined as a score of 0-17 points. Cox regression analysis was applied to adjust for a number of known and suspected factors known or suspected of being associated with cognition and mortality (e.g. sociodemographic factors, sex, smoking, alcohol consumption, depressive symptoms, and physical abilities), and yielded hazard ratios (95% confidence interval) of 1.24 (1.00-1.55) for mildly impaired and 1.73 (1.37-2.20) for severely impaired Danes compared to individuals with no impairment. Cognitive impairment predicts mortality among the very old, even after controlling for most known predictors of mortality.
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Cognitive Science, Epidemiology, Dementia, Mild Cognitive Impairment, Medicine, and 15 moreDenmark, Humans, Cox Regression, Female, Male, Alcohol Consumption, Clinical Sciences, Mini Mental State Examination, Aged, Cognitive impairment, Depressive Symptoms, Neurosciences, Confidence Interval, Cognition disorders, and Cohort Studies
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Mathematics, Applied Mathematics, Probability Theory, Econometrics, Statistics, and 14 moreBias, Probability and statistics, Algorithm, Variance, Power Law, Bias Correction, Implementation, Regression Model, Sparse Data, General Linear Model, Standard Error, Linear Regression, Distribution Function, and Generalized linear model
Workers of the ant Formica truncorum specialize in rearing females or males depending on the number of fathers of a colony. These split sex ratios increase inclusive fitness, but it has remained unknown how workers assess the number of... more
Workers of the ant Formica truncorum specialize in rearing females or males depending on the number of fathers of a colony. These split sex ratios increase inclusive fitness, but it has remained unknown how workers assess the number of patrilines in their colonies and to what extent ...
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Human chromosomes terminate in a number of repeats of the sequence TTAGGG. At birth, each chromosome end is equipped with approximately 15 kb of telomere sequence, but this sequence is short-ened during each cell division. In cell... more
Human chromosomes terminate in a number of repeats of the sequence TTAGGG. At birth, each chromosome end is equipped with approximately 15 kb of telomere sequence, but this sequence is short-ened during each cell division. In cell cultures telomere shortening is associated ...
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Research Interests:
Cognitive Science, Publishing, Cell Culture, Humans, Sex Difference, and 14 moreAcademic research, Female, Male, Statistical Significance, Commissioning, TELOMERE LENGTH, Structural Equation Model, Clinical Sciences, Aged, Theoretical Models, Telomere, Twin, Signaling pathway, and Paediatrics and reproductive medicine
The assessment of agreement in method comparison and observer variability analysis of quantitative measurements is usually done by the Bland–Altman Limits of Agreement, where the paired differences are implicitly assumed to follow a... more
The assessment of agreement in method comparison and observer variability analysis of quantitative measurements is usually done by the Bland–Altman Limits of Agreement, where the paired differences are implicitly assumed to follow a normal distribution. Whenever this assumption does not hold, the 2.5% and 97.5% percentiles are obtained by quantile estimation. In the literature, empirical quantiles have been used for this purpose. In this simulation study, we applied both sample, subsampling, and kernel quantile estimators, as well as other methods for quantile estimation to sample sizes between 30 and 150 and different distributions of the paired differences. The performance of 15 estimators in generating prediction intervals was measured by their respective coverage probability for one newly generated observation. Our results indicated that sample quantile estimators based on one or two order statistics outperformed all of the other estimators and they can be used for deriving nonp...
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Denmark experienced major socioeconomic changes, including overall population growth, during the Viking, medieval and post-medieval periods from ca. AD 800 to 1800. Archaeological skeletons provide a unique perspective on the population... more
Denmark experienced major socioeconomic changes, including overall population growth, during the Viking, medieval and post-medieval periods from ca. AD 800 to 1800. Archaeological skeletons provide a unique perspective on the population structure of Ribe, a Danish town in Jutland, during the millennium that immediately precedes the industri-alization of northern Europe. This skeletal study adds temporal depth to our understanding of an overall trend toward longer life as seen from historical records and in modern studies. Adult male and female mean age at death and mortality profiles during three time periods are based on 943 adult skeletons from three urban cemeteries that collectively represent a cross-section of this urban community. For both males and females, the mean age at death decreased slightly from the Viking (males 38.5 years, females 38.6 years) to the medieval (males 37.4 years, females 36.9 years) periods. This decline was followed by an increase in mean age at death for both sexes from the medieval to post-medieval (males 40.4 years, females 43.2 years) periods, a notable gain of 3.0 and 6.3 years for men and women, respectively.
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ABSTRACT This study evaluates a method for obtaining stature estimates for populations represented by skeletal material, with individuals buried in a supine position. During the excavation of a Danish mediaeval cemetery, in situ skeletal... more
ABSTRACT This study evaluates a method for obtaining stature estimates for populations represented by skeletal material, with individuals buried in a supine position. During the excavation of a Danish mediaeval cemetery, in situ skeletal length in the grave was measured from a point above ...
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: To elucidate whether well-known predictions of mortality are reduced or even reversed, or whether mortality is a stochastic process in the oldest old. : A multidimensional survey of the Danish 1905 cohort conducted in 1998 with... more
: To elucidate whether well-known predictions of mortality are reduced or even reversed, or whether mortality is a stochastic process in the oldest old. : A multidimensional survey of the Danish 1905 cohort conducted in 1998 with follow-up of vital status after 15 months. : Denmark. : All Danes born in 1905, irrespective of physical and mental status were approached. Two thousand two hundred sixty-two persons of 3,600 participated in this survey. : Professional interviewers collected data concerning sociodemographic factors, smoking, alcohol consumption, body mass index, physical and cognitive performance, and health during a visit at the participant's residency. Cox regression models were used to evaluate predictors of mortality. : Five hundred seventy-nine (25.7%) of the 2,249 participants eligible for the analysis died during the 15 months follow-up. Multivariate analyses showed that marital status, education, smoking, obesity, consumption of alcohol, and number of self-reported diseases were not associated with mortality. Disability and cognitive impairment were significant risk factors in men and women. In addition poor self-rated health was associated with an increase in mortality in women. : In the oldest old, several known predictors of mortality, such as sociodemographic factors, smoking, and obesity, have lost their importance, but a high disability level, poor physical and cognitive performance, and self-rated health (women only), predict mortality, which shows that mortality in the oldest old is not a stochastic process.
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In 1749 Buffon proposed a general law for the longevity of species. In retrospect this law laid the foundation for modern studies of correlations between biological variables. Buffon refers to "la durée totale de la vie", the... more
In 1749 Buffon proposed a general law for the longevity of species. In retrospect this law laid the foundation for modern studies of correlations between biological variables. Buffon refers to "la durée totale de la vie", the maximum lifespan, and claims that there is a systematic relationship between this variable and a measure of the growth period. It transpires that Buffon believed that by multiplying the age at the termination of the growth period by 7 one obtains the maximum lifespan. In vol III o the supplements to "Histoire Naturelle" he presents a table with, i.a., age at first reproduction and maximum lifespan for 31 Mammalian species, Furthermore, he claims that the growth period is equivalent to 2 times the age at first reproduction. From Buffon's data, one obtains a mean ratio of approximately 13 between maximum lifespan and age at first reproduction, where the expected ratio is 14 (2x7), i.e. very close to the observed ratio. Inspired by Buffon&#...
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Buffon and Linné were the two greatest naturalists of the 1700s. As they were both born in 1707, their 300 anniversaries were therefore celebrated in France and Sweden. At the celebration meeting at the University of Bourgogne in Dijon -... more
Buffon and Linné were the two greatest naturalists of the 1700s. As they were both born in 1707, their 300 anniversaries were therefore celebrated in France and Sweden. At the celebration meeting at the University of Bourgogne in Dijon - The Buffon Legacy - September 3-6, 2007, we presented the following paper: "Buffon and the longevity of species". In the present paper the life and work of Buffon is introduced on the basis of recent literature, including Jacques Roger's famous biography. Among non-biologists Buffon has nearly been forgotten, even though in the 1700s he was considered to be at the same level as the most famous French thinkers of the Enlightenment - Montesquieu, Voltaire, Rousseau and Diderot. His largest contributions were the publication of his comprehensive "Histoire naturelle" and his long and significant leadership of "Jardin du Roi", which he built up to become one of the best scientific institutions of Europe. Buffon's sci...
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Human chromosomes terminate in a number of repeats of the sequence TTAGGG. At birth, each chromosome end is equipped with approximately 15 kb of telomere sequence, but this sequence is shortened during each cell division. In cell cultures... more
Human chromosomes terminate in a number of repeats of the sequence TTAGGG. At birth, each chromosome end is equipped with approximately 15 kb of telomere sequence, but this sequence is shortened during each cell division. In cell cultures telomere shortening is associated with senescence, a phenomenon that has also been observed in normal adult tissues, indicating that telomere loss is associated with organismal ageing. Previous work has established that the rate of telomere loss in humans is age dependent, and recent work shows a sex-specific difference in telomere length and shortening in individuals over the age span of 20 to 75 years. Here, terminal restriction fragment lengths on DNA purified from whole blood were measured to examine the mean telomere length in a cross-sectional cohort of 816 Danish individuals of age 73 to 101 years. In this age group, females show a linear correlation between telomere length and age, whereas the pattern tends to be nonlinear (quadratic in age...
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Biochemical liver function tests are widely used in the clinic and are some of the most frequently used tests in screening for diseases in older age groups. The aim of the present study was to estimate the relative importance of genetic... more
Biochemical liver function tests are widely used in the clinic and are some of the most frequently used tests in screening for diseases in older age groups. The aim of the present study was to estimate the relative importance of genetic and environmental factors to variations in these tests among the elderly. We conducted a survey among Danish twins, 73-102 years of age, identified in the population-based Danish Twin Registry. Among the 2749 individuals in the study population, an interview was conducted with 79%. From these, a blood sample was collected from 290 same-sex twin pairs, total of 580 subjects, within a 6-month period and analyzed for alanine aminotransferase (ALT), lactate dehydrogenase (LDH), gamma-glutamyltransferase (GGT), bilirubin, and albumin. The interview included questions about alcohol consumption and body mass index (BMI; self-calculated height and weight). Heritability (proportion of the population variance attributable to genetic variation) was estimated us...
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Genetics, Clinical Chemistry, Denmark, Female, Clinical, and 15 moreBlood sampling, Alcohol Drinking, Exploration, Genetic determinism, Bilirubin, Body Mass Index, Alcohol Consumption, Clinical Sciences, Aged, Genetic variation, Environment, Age Groups, Alanine Transaminase, Genetic factors, and Environmental factor
The morphological regionalization of European Mesolithic populations was studied by discriminant analysis. Samples from four localities were compared employing craniometric variables. The general conclusion was that there is evidence for... more
The morphological regionalization of European Mesolithic populations was studied by discriminant analysis. Samples from four localities were compared employing craniometric variables. The general conclusion was that there is evidence for regionalization in the Late mesolithic in Europe, and a clinical pattern of variation was not detected. These results are in agreement with archaeological reconstructions of the population structure in the Late Mesolithic Europe.
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Research Interests:
Research Interests:
Cognitive Science, Publishing, Cell Culture, Humans, Sex Difference, and 14 moreAcademic research, Female, Male, Statistical Significance, Commissioning, TELOMERE LENGTH, Structural Equation Model, Clinical Sciences, Aged, Theoretical Models, Telomere, Twin, Signaling pathway, and Paediatrics and reproductive medicine
Despite strong epidemiologic evidence in favor of a genetic component in the etiology of... more
Despite strong epidemiologic evidence in favor of a genetic component in the etiology of Graves' disease, few hereditary risk factors have been consistently identified. The term genetic anticipation denotes a decrease in the age of onset as disease is passed through generations. In the past 5 years, genetic anticipation has been described in immune-mediated diseases such as rheumatoid arthritis and chronic inflammatory bowel disease, and recently this phenomenon has been linked to unstable expanded trinucleotide repeat sequences in several diseases. If present in Graves' disease, anticipation could provide clues to its genetic etiology. The aim of the present study was to investigate whether genetic anticipation may occur in Graves' disease. Age at diagnosis and age at ascertainment were registered and compared in 33 same-gender parent-offspring pairs with Graves' disease from multiply affected families primarily ascertained for a genetic linkage study. The mean age at diagnosis was 46.6 years (range, 16-77) in the parents and 34.1 years (range, 16-44) in the children. The difference in the mean age at diagnosis between parents and their children was 12.5 years (95% confidence interval 3.0-21.9), p = 0.010. Children were younger than their parents at diagnosis in 25 of 33 pairs (76%). In 7 pairs (21%), the parent was diagnosed after the child according to the calendar years. Essentially similar results were obtained after controlling for gender and smoking habits. In conclusion, our data suggest that patients in the second affected generation seem to acquire their disease at an earlier time in life in familial cases of Graves' disease, indicating that genetic anticipation might occur.
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Classic twin study. To determine the heritability of neck pain in persons 70 years of age and older. Previous studies have shown a moderate effect of genetic factors on back pain in the elderly. Genetic influence on neck pain in old age... more
Classic twin study. To determine the heritability of neck pain in persons 70 years of age and older. Previous studies have shown a moderate effect of genetic factors on back pain in the elderly. Genetic influence on neck pain in old age is unknown. Data on the 1-month prevalence of neck pain from twin pairs participating in the population based Longitudinal Study of Aging Danish Twins formed the basis of this analysis. To assess twin similarity, probandwise concordance rates, odds ratios, and tetrachoric correlations were calculated and compared for monozygotic and dizygotic twins. Further, heritability estimates were calculated using bivariate probit estimation. A total of 2,108 twin individuals, including 1,054 complete twin pairs, answered the question related to neck pain at intake into the Longitudinal Study of Aging Danish Twins study. Low and nonsignificant probandwise concordance rates, odds ratios, and tetrachoric correlations were found for both men and women in monozygotic and dizygotic twin pairs, indicating small or negligible genetic effects. Heritability estimates adjusted for age and significant environmental risk factors (rheumatoid arthritis, osteoarthritis, disc prolapse, and coronary heart disease) showed no significant additive genetic, dominant genetic, or common environmental effects. Genetic factors do not play an important role in the liability to neck pain in persons 70 years of age or older.
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Self-reported 1-month prevalence of back pain in older twins assessed at intake in a population-based longitudinal survey. To determine the relative contribution of genetic and environmental factors to back pain in old age. To date,... more
Self-reported 1-month prevalence of back pain in older twins assessed at intake in a population-based longitudinal survey. To determine the relative contribution of genetic and environmental factors to back pain in old age. To date, genetic contributions to back pain in old age have not been assessed, to the authors' best knowledge. Interview data given at entry into a nationwide cohort-sequential population-based survey of Danish twins aged 70 years and older in 1995, 1997, 1999, and 2001 form the basis of this analysis. Analysis of twin similarity was estimated using probandwise concordance rates, odds ratios, and tetrachoric correlations for back pain. Heritability (proportion of the population variance attributable to genetic variation) was estimated by bivariate probit estimation and adjusted for known significant environmental factors. Odds ratios for known environmental effects were estimated after controlling for age, sex, and genetic effects. Modest and nonsignificant differences between monozygotic and dizygotic twin pairs were found for probandwise concordance rates, odds ratios, and tet-rachoric correlations for both men and women. In the bivariate probit estimation, a current or previous diagnosis of osteoporosis, degenerative joint disease, or lumbar disc prolapse was found to significantly affect the risk of back pain. Additive genetic effects explained approximately one fourth of the liability to report back pain in men and none of the occurrence in women. Individual environmental effects were found to explain roughly 75% of the occurrence of back pain in men and 100% in women. Additive genetic effects are modest contributors to back pain in older men but not in women. A current or previous medical diagnosis of osteoporosis, degenerative joint disease, or lumbar disc prolapse is-strongly associated with back pain, also when genetic factors are controlled for. Because of inherent methodologic issues, this estimate of the genetic influence on back pain in old age is probably conservative.
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Little is known about specific Danish drinking patterns. This paper investigates how various socio-demographic factors are related to Danish alcohol consumption with special focus on age and sex. Data come from a national telephone survey... more
Little is known about specific Danish drinking patterns. This paper investigates how various socio-demographic factors are related to Danish alcohol consumption with special focus on age and sex. Data come from a national telephone survey of the Danish general population conducted in 2003 with a final sample size of 2,030 cases. Measures of beverage specific current drinking, overall drinking, daily drinking, heavy episodic drinking, mean consumption, volume per drinking occasion and frequency of drinking were analysed. A little over 5% of the population are abstainers. Fourteen per cent of men and 9% of women are heavy drinkers; 38% of men and 18% of women are heavy episodic drinkers. Youth of both sexes drink heavily, and especially in a binge drinking style. Regular, more temperate drinking is associated with increasing age. Multivariate analyses suggest that other than age and sex, classical socioeconomic factors do not play a great a role in determining drinking patterns. Social integrative factors in particular influence women's drinking. With respect to the rest of Europe and North America, Danes consume high levels of alcohol with a large percentage of youth drinking in a binge pattern. Classical socioeconomic factors play a lesser role in determining drinking patterns compared to other Western countries. Longitudinal studies and studies of alcohol-related consequences in the Danish general population should be conducted to better formulate alcohol and public health policy.
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Research Interests:
To determine the predictive value on survival of optic neuritis (ON) as onset manifestation of MS. We used data obtained from the Danish Multiple Sclerosis Registry, which includes virtually all patients diagnosed with MS in Denmark. From... more
To determine the predictive value on survival of optic neuritis (ON) as onset manifestation of MS. We used data obtained from the Danish Multiple Sclerosis Registry, which includes virtually all patients diagnosed with MS in Denmark. From 1949 to 1990, 7,548 unselected patients fulfilling standardized diagnostic criteria of MS were registered. The onset manifestation of MS was known in 6,923 patients, and was ON in 1,282 patients (19%). The mean age at onset was 31.1 years for these patients compared with 34.8 years for patients with another or unknown onset manifestation of MS (non-ON) (p < 0.001). The mean delay from the first known manifestation of MS to the final diagnosis of MS was 6.1 years (ON) and 4.2 years (non-ON). The median survival time from onset of ON was 30 years in men (compared with 41 years in the matched general male population) and 40 years in women (versus 47 years). The excess death rate increased with age at onset of MS in people of each sex. Excess death rate for women differed significantly between patients with ON as onset manifestation and patients with another or unknown onset manifestation of MS (8.3 versus 13.0). In patients with ON as onset manifestation of MS, the excess death rate was significantly higher in men (14.0) than in women (8.3). ON as onset manifestation of MS indicates a more favorable prognosis of survival of MS judged by excess death rate only in women.
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The occurrence of multiple sclerosis (MS) in twins has not previously been studied in complete nationwide data sets. The existence of almost complete MS and twin registries in Denmark ensures that essentially unbiased samples of MS cases... more
The occurrence of multiple sclerosis (MS) in twins has not previously been studied in complete nationwide data sets. The existence of almost complete MS and twin registries in Denmark ensures that essentially unbiased samples of MS cases among twins can be obtained. In this population-based study, virtually all Danish MS cases among twins born before 1983 with onset of MS after 1948 and diagnosis before 1 January 1997 were identified. Of 13 286 MS cases, 178 were twins and, of these 164 twin pairs were discordant and seven were concordant. We found significantly higher proband-wise concordance among monozygotic twins than dizygotic twins, with estimated proband-wise concordances of 24% (95% confidence interval (CI): 5-39%) for monozygotic and 3% (95% CI: 0-8%) for dizygotic twins. Thus, a monozygotic twin whose co-twin has MS has a 24% risk of developing the disease, while the corresponding risk for a dizygotic twin is only 3%. Our results largely confirm previously published concor...
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We investigated the risks of twins for multiple sclerosis (MS). Our data are linked registers of all Danish twins and of all Danes born between 1920 and 1970 in whom MS was diagnosed before 1997. We compared differences in the risks for... more
We investigated the risks of twins for multiple sclerosis (MS). Our data are linked registers of all Danish twins and of all Danes born between 1920 and 1970 in whom MS was diagnosed before 1997. We compared differences in the risks for MS by Cox regression and standardized incidence ratios. Our analyses suggest that dizygotic twins have an approximately 60% lower risk for MS than monozygotic twins and a 20% lower risk than singletons. Monozygotic twins appear to have a somewhat higher risk for MS than singletons albeit not statistically significant. We offer no biological explanation for our findings, but suggest that either sharing fetal life with a genotypically different individual is beneficial for the immune system or that there is a linkage between the genes that influence dizygotic twinning and other genes that protect against MS.
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Research Interests:
ABSTRACT We review the Fisher scoring and EM algorithms for incomplete multivariate data from an estimating function point of view, and examine the corresponding quasi-score functions under second-moment assumptions. A bias-corrected... more
ABSTRACT We review the Fisher scoring and EM algorithms for incomplete multivariate data from an estimating function point of view, and examine the corresponding quasi-score functions under second-moment assumptions. A bias-corrected REML-type estimator for the covariance matrix is derived, and the Fisher, Godambe and empirical sandwich information matrices are compared. We make a numerical investigation of the two algorithms, and compare with a hybrid algorithm, where Fisher scoring is used for the mean vector and the EM algorithm for the covariance matrix.
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... Petersen b & Kirsten O. Kyvik c ... pairs) under dependence ( ) are shown in Table 2. In the Gaussian case, in the presence of clustering, the classical F-test and the unclustered version of the Levene's test no... more
... Petersen b & Kirsten O. Kyvik c ... pairs) under dependence ( ) are shown in Table 2. In the Gaussian case, in the presence of clustering, the classical F-test and the unclustered version of the Levene's test no longer control the Type I error rate the empirical size almost doubles. ...
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ABSTRACT The lack of a common statistical approach describing the distribution and dispersion pattern of marine benthic animals has often hampered the comparability among studies. The purpose of this study is therefore to apply an... more
ABSTRACT The lack of a common statistical approach describing the distribution and dispersion pattern of marine benthic animals has often hampered the comparability among studies. The purpose of this study is therefore to apply an alternative approach, Taylor's power law, to data on spatial and temporal distribution of 9 dominating benthic invertebrate species from two study areas, the estuaries Odense Fjord and Roskilde Fjord, Denmark. The slope (b) obtained from the power relationship of sample variance (s2) versus mean (μ) appears to be species-specific and independent of location and time. It ranges from a low of ~ 1 for large-bodied (> 1 mg AFDW) species (e.g. Marenzelleria viridis, Nereis diversicolor) to a high of 1.6–1.9 for small-bodied (< 1 mg AFDW) species (e.g. Pygospio elegans and Tubificoides benedii). Accordingly, b is apparently a valuable species-specific dispersion index based on biological factors such as behavior and intraspecific interactions. Thus, at the examined spatial scale, the more intense intraspecific interactions (e.g. territoriality) cause less aggregated distribution patterns among large- than small-bodied invertebrates. The species-specific interactions seem sufficiently strong to override environmental influences (e.g. water depth and sediment type). The strong linear relationship between the slope b and intercept log(a) from the power relationship is remarkably similar for all surveys providing a common slope of − 1.63 with the present sampling approach. We suggest that this relationship is an inherent characteristic of Taylor's power law, and that b as a dispersion index may be biased by e.g. sampling errors when this relationship is weak. The correlation strength between b and log(a) could therefore be envisioned as a data quality check.
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Research Interests:
Out of five strains of Atlantic salmon Salmo salar of 1+ years released upstream of a fyke net in the River Gudenaa in 1996, three, Lagan, A}tran and Corrib, migrated immediately, 50% of the recaptured fish reaching the net in 36 days.... more
Out of five strains of Atlantic salmon Salmo salar of 1+ years released upstream of a fyke net in the River Gudenaa in 1996, three, Lagan, A}tran and Corrib, migrated immediately, 50% of the recaptured fish reaching the net in 36 days. Burrishoole and Conon fish migrated ...
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Research Interests:
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Research Interests:
The consistent findings of a negative correlation between telomere length and replicative potential of cultured cells, as well as a decreasing telomere length in a number of different tissues in humans with age, have led to the suggestion... more
The consistent findings of a negative correlation between telomere length and replicative potential of cultured cells, as well as a decreasing telomere length in a number of different tissues in humans with age, have led to the suggestion that telomeres play a role in cellular aging in vivo and ultimately even in organismal aging. Furthermore, one small longitudinal study of elderly individuals has suggested that longer telomeres are associated with better survival. Telomere length was measured as mean terminal restriction fragment length on blood cells from 812 persons, age 73 to 101 years, who participated in population-based surveys in 1997-1998. Among the participants were 652 twins. The participants were followed up through the Danish Civil Registration system until January 2005, at which time 412 (51%) were dead. Univariate Cox regression analyses revealed that longer telomeres were associated with better survival (hazard ratios = 0.89 [95% confidence interval = 0.76-1.04] per 1 kb in males and 0.79 [0.72-0.88] per 1 kb in females, respectively). However, including age in the analyses changed the estimates to 0.97 (0.83-1.14) and 0.93 (0.85-1.03), respectively. Intrapair comparison showed that among 175 twin pairs in which at least one died during follow up, it was the twin with the shorter telomere length who died first in 97 (55%) of the pairs (95% confidence interval = 48-63%). We could not confirm the recently reported negative correlation between telomere length and obesity or between telomere length and smoking. This longitudinal study of the elderly and oldest old does not support the hypothesis that telomere length is a predictor for remaining lifespan once age is controlled for.
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The influences of environmental factors on the male reproductive system have been much debated over the last 3 decades. We studied the impact of genes and environment on semen quality, sex hormone levels, and sperm chromatin stability by... more
The influences of environmental factors on the male reproductive system have been much debated over the last 3 decades. We studied the impact of genes and environment on semen quality, sex hormone levels, and sperm chromatin stability by using a twin design. The study population consisted of monozygotic and dizygotic twins from the population-based Danish Twin Registry and a random selection of pairs of singleton brothers from the Danish Civil Registration System. All men were 20 to 45 years of age. The study population comprised 100 monozygotic twin brothers (50 pairs), 102 dizygotic twins (51 pairs), and 102 single-born brothers (51 pairs). A semen sample and blood sample were collected from all participants. Heritability was estimated to account for 20% (95% confidence interval = 0% to 68%) of the variation in sperm density. A higher heritability was found for the hormones reflecting Sertoli cell function (inhibin B, 76% [36% to 84%] and follicle-stimulating hormone, 81% [40% to 88%]) and for percent morphologic normal cells (41% [0% to 60%] and sperm chromatin parameters (mean alphaT, 68% [34% to 81%] and COMP alphaT, 72% [25% to 82%], respectively). Our study indicates a substantial hereditary component in plasma levels of hormones reflecting Sertoli cell function and in sperm cell chromatin stability and morphology. The environmental contribution (including the prenatal environment) appeared to be largest for sperm count.
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In a recent, hospital-based report, we described a small series of 5 patients with unilateral, more or less chronic, severe forehead pain, that could be transitorily abated by anaesthetic blockade of the supraorbital nerve and more... more
In a recent, hospital-based report, we described a small series of 5 patients with unilateral, more or less chronic, severe forehead pain, that could be transitorily abated by anaesthetic blockade of the supraorbital nerve and more permanently abated by ‘liberation’ operation directed towards the nerve exit area at the supraorbital notch. However, epidemiological data on supraorbital neuralgia are lacking. Among 1838 18-65-year-old inhabitants in Vågå (88.6% of the eligible ones), there were 10 who presented the following clinical picture: (1) Unilateral forehead/ocular pain, not diagnosed or diagnosable as any other, particular, unilateral headache; (2) Steadfast unilaterality; (3) Increased tenderness upon pressure over the exit site of the supraorbital nerve (incisura frontalis) on that side —in those who were in an active phase; (4) Foregoing trauma in the forehead/supraorbital rim area, ipsilaterally. In approximately half the cases, there was a moderate, ipsilateral sensory lo...
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Bioacoustics The International Journal of Animal Sound and its Recording, 2009, Vol. 19, pp. 4965 © 2009 AB Academic Publishers ... CHANGES IN CLICK SOURCE LEVELS WITH DISTANCE TO TARGETS: STUDIES OF FREE-RANGING WHITE-BEAKED DOLPHINS ...