Farber's conjecture for planar graphs

We prove that the ordered configuration spaces of planar graphs have the highest possible topological complexity generically, as predicted by a conjecture of Farber. Our argument establishes the same generic maximality for all higher topological complexities. We include some discussion of the non-planar case, demonstrating that the standard approach to the conjecture fails at a fundamental level

Modelling regional variation of first-time births in Denmark 1980-1994 by an age-period-cohort model

Despite the small size of Denmark, there have traditionally been rather consistent regional differences in fertility rates. We apply the statistical age-period-cohort model to include the effect of these three time-related factors thereby concisely illuminating the regional differences of first-time births in Denmark. From the Fertility of Women and Couples Dataset we obtain data on number of births by nulliparous women by year (1980-1994), age (15-45) and county of residence. We show that the APC-model describes the fertility rates of nulliparous women satisfactorily. To catch the regional variation an interaction parameter between age and county is necessary, which provides a surprisingly good description suggesting that the county-specific age-distributions of first-time fertility rates differ. Our results are in general agreement with the 'moral geography' concepts of Tonboe (2001).age-period-cohort models, Denmark, fertility, fertility rate, nulliparous women, regional variation

On the accuracy of analysed low temperatures in the stratosphere

International audienceThe accuracy of ECMWF (European Centre for Medium-Range Weather Forecasts) temperatures has been investigated by comparison to radiosonde temperatures. Particularly, the extent of temperatures below which Polar Stratospheric Clouds (PSCs) consisting of nitric acid trihydrate can exist (TNAT) has been studied. In the 1999/2000 winter analyses and in the 40 year reanalyses (ERA40) from the winter 1996/1997 the analysed extent agrees quite well with the radiosondes extent, whereas the 2002/2003 winter analyses considerably overestimate the extent from 40-11 hPa due to a general cold bias. Close to the frost point small-scale temperature variations, which ECMWF does not catch, substantially increase the extent of these low temperatures. Some of these small-scale variations are caused by lee-waves

The Fertility Pattern of Twins and the General Population Compared: Evidence from Danish Cohorts 1945-64

Twin studies provide an important possibility for demographers to analyze patterns of heritability and to estimate structural models with controls for endowments. These possibilities are increasingly used in the context of fertility and related behaviors. A close congruence between the fertility patterns of twins and that of the general population, however, is an essential pre-condition in order to generalize the results of twin-based investigations of fertility and related behaviors to the general population. In this paper we therefore compare the fertility of Danish twins born 1945--64 to the fertility pattern of the general population born during the same period. Our analyses find a very close correspondence between the fertility pattern of twins and of the general population. There exist only few statistically significant differences, and the primary difference pertains to the fact that female twins have a slightly later onset of childbearing than non-twins. There are virtually no relevant differences between the fertility patterns of dizygotic and monozygotic twins.cohort fertility, Denmark, fertility, twin studies

Passive exercise of the hind limbs after complete thoracic transection of the spinal cord promotes cortical reorganization.

Physical exercise promotes neural plasticity in the brain of healthy subjects and modulates pathophysiological neural plasticity after sensorimotor loss, but the mechanisms of this action are not fully understood. After spinal cord injury, cortical reorganization can be maximized by exercising the non-affected body or the residual functions of the affected body. However, exercise per se also produces systemic changes - such as increased cardiovascular fitness, improved circulation and neuroendocrine changes - that have a great impact on brain function and plasticity. It is therefore possible that passive exercise therapies typically applied below the level of the lesion in patients with spinal cord injury could put the brain in a more plastic state and promote cortical reorganization. To directly test this hypothesis, we applied passive hindlimb bike exercise after complete thoracic transection of the spinal cord in adult rats. Using western blot analysis, we found that the level of proteins associated with plasticity - specifically ADCY1 and BDNF - increased in the somatosensory cortex of transected animals that received passive bike exercise compared to transected animals that received sham exercise. Using electrophysiological techniques, we then verified that neurons in the deafferented hindlimb cortex increased their responsiveness to tactile stimuli delivered to the forelimb in transected animals that received passive bike exercise compared to transected animals that received sham exercise. Passive exercise below the level of the lesion, therefore, promotes cortical reorganization after spinal cord injury, uncovering a brain-body interaction that does not rely on intact sensorimotor pathways connecting the exercised body parts and the brain

Resistens over for sædskiftesygdomme i frøbælgplanter - er det muligt?

Sædskiftesygdomme i frøbælgplanter holdes traditionelt nede med flere dyrkningsfrie år mellem samme art. I FØJO-projektet GRAINLEG, der er et samarbejde mellem DJF Flakkebjerg, KVL og Toft Planteforædling, arbejder vi med at forbedre resistensen overfor jordbårne sygdomme, primært i ært og lupin. Vi søger at identificere resistent materiale til anvendelse i forædling og arbejder med at udvikle metoder, der bl.a. kan anvendes i sortsafprøvningen til test af resistens mod ærterodråd (Aphanomyces euteiches) samt Fusarium i ært og Fusarium rodråd- og visnesyge i lupin. Gentagen lupindyrkning kan medføre opformering af jordbårne patogener, ofte Fusarium spp., der resulterer i rodråd og visnesyge (lupintræt jord). Såfremt lupin skal vinde indpas som proteinafgrøde, er det derfor ønskeligt at anvende sorter med høj Fusarium resistens. I 2003 blev 26 sorter testet på et lupintræt areal. Forsøget viste overordentlig store forskelle i sorternes resistensniveau – rangerende fra normal vækst til fuldstændig nedvisning (tabel 1). Vores undersøgelser tyder derfor på, at man kan få alvorlige problemer med Fusarium, hvis de mest modtagelige sorter anvendes for ofte i sædskiftet