Physical activity attenuates the body mass index-increasing influence of genetic variation in the FTO gene 1-3.

BACKGROUND: Intronic variation in the FTO (fat mass and obesity-associated) gene has been unequivocally associated with increased body mass index (BMI; in kg/m(2)) and the risk of obesity in populations of different ethnicity. OBJECTIVE: We examined whether this robust genetic predisposition to obesity can be attenuated by being more physically active. DESIGN: The FTO variant rs1121980 was genotyped in 20,374 participants (39-79 y of age) from the European Prospective Investigation into Cancer and Nutrition-Norfolk Study, an ethnically homogeneous population-based cohort. Physical activity (PA) was assessed with a validated self-reported questionnaire. The interaction between rs1121980 and PA on BMI and waist circumference (WC) was examined by including the interaction term in mixed-effect models. RESULTS: We confirmed that the risk (T) allele of rs1121980 was significantly associated with BMI (0.31-unit increase per allele; P < 0.001) and WC (0.77-cm increase per allele; P < 0.001). The PA level attenuated the effect of rs1121980 on BMI and WC; ie, whereas in active individuals the risk allele increased BMI by 0.25 per allele, the increase in BMI was significantly (P for interaction = 0.004) more pronounced (76%) in inactive individuals (0.44 per risk allele). We observed similar effects for WC (P for interaction = 0.02): the risk allele increased WC by 1.04 cm per allele in inactive individuals but by only 0.64 cm in active individuals. CONCLUSIONS: Our results showed that PA attenuates the effect of the FTO rs1121980 genotype on BMI and WC. This observation has important public health implications because we showed that a genetic susceptibility to obesity induced by FTO variation can be overcome, at least in part, by adopting a physically active lifestyle.

Long-term variations in the open solar flux and possible links to Earth’s climate

Recent paleoclimate studies provide strong evidence for an association between cosmogenic isotope production and Earth’s climate throughout the holecene. These isotopes are generated by the bombardment of Earth’s atmosphere by galactic cosmic rays, the fluxes of which vary in approximately inverse proportion to the total open magnetic flux of the Sun. This paper discusses how results from the Ulysses spacecraft allow us to quantify the open solar flux from observations of near-Earth interplanetary space and to study its long-term variations using the homogeneous record of geomagnetic activity. A study of the results and of their accuracy is presented. The two proposed mechanisms that could lead to the open solar flux being a good proxy for solar-induced climate change are discussed: the first is the modulation of the production of some types of cloud by the air ions produced by cosmic rays; the second is a variation in the total or spectral solar irradiance, in association with changes in the open flux. Some implications for our understanding of anthropogenic climate change are discussed.

Long-term changes in the solar photosphere associated with changes in the coronal source flux

Using sunspot observations from Greenwich and Mount Wilson, we show that the latitudinal spread of sunspot groups has increased since 1874, in a manner that closely mirrors the long-term (similar to 100 year) changes in the coronal source flux, F-s, as inferred from geomagnetic activity. This latitude spread is shown to be well correlated with the flux emergence rate required by the model of the coronal source flux variation by Solanki er al. [2000]. The time constant for the decay of this open flux is found to be 3.6 +/-0.8 years. Using this value, and quantifying the photospheric flux emergence rate using the latitudinal spread of sunspot groups, the model reproduces the observed coronal source flux variation. The ratio of the 100-year drift to the solar cycle amplitude for the flux emergence rate is found to be half of the same ratio for F-s.

Long term changes in EUV and X-ray emissions from the solar corona and chromosphere as measured by the response of the Earth’s ionosphere during total solar eclipses from 1932 to 1999

Measurements of the ionospheric E region during total solar eclipses in the period 1932-1999 have been used to investigate the fraction of Extreme Ultra Violet and soft X-ray radiation, phi, that is emitted from the limb corona and chromosphere. The relative apparent sizes of the Moon and the Sun are different for each eclipse, and techniques are presented which correct the measurements and, therefore, allow direct comparisons between different eclipses. The results show that the fraction of ionising radiation emitted by the limb corona has a clear solar cycle variation and that the underlying trend shows this fraction has been increasing since 1932. Data from the SOHO spacecraft are used to study the effects of short-term variability and it is shown that the observed long-term rise in phi has a negligible probability of being a chance occurrence.

Long-term variations in the magnetic field of the Sun and possible implications for terrestrial climate

Recent studies of the variation of geomagnetic activity over the past 140 years have quantified the "coronal source" or "open" magnetic flux F-s that leaves the solar atmosphere and enters the heliosphere and have shown that it has risen, on average, by 34% since 1963 and by 140% since 1900. This variation is reflected in studies of the heliospheric field using isotopes deposited in ice sheets and meteorites by the action of galactic comic rays. The variation has also been reproduced using a model that demonstrates how the open flux accumulates and decays, depending on the rate of flux emergence in active regions and on the length of the solar cycle. The cosmic ray flux at energies > 3 GeV is found to have decayed by about 15% during the 20(th) century (and by about 4% at > 13 GeV). We show that the changes in the open flux do reflect changes in the photospheric and sub-surface field which offers an explanation of why open flux appears to be a good proxy for solar irradiance extrapolation. Correlations between F-s, solar cycle length, L, and 11-year smoothed sunspot number, R-11, explain why the various irradiance reconstructions for the last 150 years are similar in form. Possible implications of the inferred changes in cosmic ray flux and irradiance for global temperatures on Earth are discussed.

Solar causes of the long-term increase in geomagnetic activity

We analyze the causes of the century-long increase in geomagnetic activity, quantified by annual means of the aa index, using observations of interplanetary space, galactic cosmic rays, the ionosphere, and the auroral electrojet, made during the last three solar cycles. The effects of changes in ionospheric conductivity, the Earth's dipole tilt, and magnetic moment are shown to be small; only changes in near-Earth interplanetary space make a significant contribution to the long-term increase in activity. We study the effects of the interplanetary medium by applying dimensional analysis to generate the optimum solar wind-magnetosphere energy coupling function, having an unprecedentedly high correlation coefficient of 0.97. Analysis of the terms of the coupling function shows that the largest contributions to the drift in activity over solar cycles 20-22 originate from rises in the average interplanetary magnetic field (IMF) strength, solar wind concentration, and speed; average IMF orientation has grown somewhat less propitious for causing geomagnetic activity. The combination of these factors explains almost all of the 39% rise in aa observed over the last three solar cycles. Whereas the IMF strength varies approximately in phase with sunspot numbers, neither its orientation nor the solar wind density shows any coherent solar cycle variation. The solar wind speed peaks strongly in the declining phase of even-numbered cycles and can be identified as the chief cause of the phase shift between the sunspot numbers and the aa index. The rise in the IMF magnitude, the largest single contributor to the drift in geomagnetic activity, is shown to be caused by a rise in the solar coronal magnetic field, consistent with a rise in the coronal source field, modeled from photospheric observations, and an observed decay in cosmic ray fluxes.

Short-term variability of solar wind number density, speed and dynamic pressure as a function of the interplanetary magnetic field components: A survey over two solar cycles

The variability of hourly values of solar wind number density, number density variation, speed, speed variation and dynamic pressure with IMF Bz and magnitude |B| has been examined for the period 1965–1986. We wish to draw attention to a strong correlation in number density and number density fluctuation with IMF Bz characterised by a symmetric increasing trend in these quantities away from Bz = 0 nT. The fluctuation level in solar wind speed is found to be relatively independent of Bz. We infer that number density and number density variability dominate in controlling solar wind dynamic pressure and dynamic pressure variability. It is also found that dynamic pressure is correlated with each component of IMF and that there is evidence of morphological differences between the variation with each component. Finally, we examine the variation of number density, speed, dynamic pressure and fluctuation level in number density and speed with IMF magnitude |B|. Again we find that number density variation dominates over solar wind speed in controlling dynamic pressure.

Public real estate and the term structure of interest rates: a cross-country study

Using a variation of the Nelson-Siegel term structure model we examine the sensitivity of real estate securities in six key global markets to unexpected changes in the level, slop and curvature of the yield curve. Our results confirm the time-sensitive nature of the exposure and sensitivity to interest rates and highlight the importance of considering the entire term structure of interest rates. One issue that is of particular of interest is that despite the 2007-9 financial crisis the importance of unanticipated interest rate risk weakens post 2003. Although the analysis does examine a range of markets the empirical analysis is unable to provide definitive evidence as to whether REIT and property-company markets display heightened or reduced exposure.

Calibration Strategies Designed For Long Term Sediment Transport Modelling

The presented work deals with the calibration of a 2D numerical model for the simulation of long term bed load transport. A settled basin along an alpine stream was used as a case study. The focus is to parameterise the used multi fractional transport model such that a dynamically balanced behavior regarding erosion and deposition is reached. The used 2D hydrodynamic model utilizes a multi-fraction multi-layer approach to simulate morphological changes and bed load transport. The mass balancing is performed between three layers: a top mixing layer, an intermediate subsurface layer and a bottom layer. Using this approach bears computational limitations in calibration. Due to the high computational demands, the type of calibration strategy is not only crucial for the result, but as well for the time required for calibration. Brute force methods such as Monte Carlo type methods may require a too large number of model runs. All here tested calibration strategies used multiple model runs utilising the parameterization and/or results from previous run. One concept was to reset to initial bed elevations after each run, allowing the resorting process to convert to stable conditions. As an alternative or in combination, the roughness was adapted, based on resulting nodal grading curves, from the previous run. Since the adaptations are a spatial process, the whole model domain is subdivided in homogeneous sections regarding hydraulics and morphological behaviour. For a faster optimization, the adaptation of the parameters is made section wise. Additionally, a systematic variation was done, considering results from previous runs and the interaction between sections. The used approach can be considered as similar to evolutionary type calibration approaches, but using analytical links instead of random parameter changes.

Spatio-temporal variation in seed production in three Euphorbia species and the role of animals on seed fate

Comparative studies on the reproductive biology of co-occurring related plant species have provided valuable information for the interpretation of ecological and evolutionary phenomena, with direct application in conservation management of plant populations. The aims of this thesis were to identify the causes of pre-dispersal reproductive losses in three Euphorbia species (the Mediterranean E. characias and the narrow endemics E. pedroi and E. welwitschii) and evaluate the variation of their effects in time, space and between individuals and species. Furthermore, we intended to study elaiosomes’ fatty acid profiles for the three Euphorbia and assess the role played by the elaiosome in ant attraction. Finally, we aimed to identify the major seed dispersal agents for each Euphorbia species in each site and study differences in short term seed fate due to differences in ant behaviour. The results indicated that intact seed production differed significantly between the three Euphorbia, mostly due to differences in cyathia production. Losses to pre-dispersal seed predators were proportionately larger for the endemic species which also suffered higher losses resulting in flower, fruit (in E. welwitschii) and seed abortion (in E. pedroi). The elaiosomes of E. pedroi are poor in fatty acids and for this reason seeds of this species were removed in lower proportion by mutualistic dispersers than those of their congeners, being more prone to seed predation. Two larger ant species – Aphaenogaster senilis and Formica subrufa – were responsible for a larger percentage of removals with seeds being transported at larger distances and being discarded in the vicinity of their nests following elaiosome removal. Our results highlight the role of insect-plant interactions as major determinants of seed survival for the three study plants and call for the need to include more information on insect-plant interactions in plant conservation programmes.

Seasonal variation in wood formation of Cedrela fissilis (Meliaceae)

Cambial activity and periodicity of secondary xylem formation in Cedrela fissilis, a semi-ring-porous species, were studied. Wood samples were collected periodically from 1996 to 2000. The phenology was related to climate data of the region. The cambium has one active and one dormant period per year. The active period coincides with the wet season when trees leaf-out. The dormant period coincides with the dry season when trees lose their leaves. Growth rings are marked by parenchyma bands that begin to be formed, together with the small latewood vessels, just before the cambium becomes dormant at the beginning of the dry season. These bands are added to when the cambium reactivates in the wet season. At this time, the large earlywood vessels of the growth rings are also formed. As these bands consist of both terminal and initial parenchyma, we suggest the general term marginal bands be used to describe them. The growth layers vary in width among and within the trees.

Interspecific variation in the defensive responses of obligate plant-ants: experimental tests and consequences for herbivory

The aggressive behavior of ants that protect plants from herbivores in exchange for rewards such as shelter or food is thought to be an important form of biotic defense against herbivory, particularly in tropical systems. To date, however, no one has compared the defensive responses of different ant taxa associated with the same plant species, and attempted to relate these differences to longer-term efficacy of ant defense. We used experimental cues associated with herbivory-physical damage and extracts of chemical volatiles from leaf tissue-to compare the aggressive responses of two ant species obligately associated with the Amazonian myrmecophyte Tococa bullifera (Melastomataceae). We also conducted a colony removal experiment to quantify the level of resistance from herbivores provided to plants by each ant species. Our experiments demonstrate that some cues eliciting a strong response from one ant species elicited no response by the other. For cues that do elicit responses, the magnitude of these responses can vary interspecifically. These patterns were consistent with the level of resistance provided from herbivores to plants. The colony removal experiment showed that both ant species defend plants from herbivores: however, herbivory was higher on plants colonized by the less aggressive ant species. Our results add to the growing body of literature indicating defensive ant responses are stimulated by cues associated with herbivory. However, they also suggest the local and regional variation in the composition of potential partner taxa could influence the ecology and evolution of defensive mutualisms in ways that have previously remained unexplored.

Variation of the Equator due to a Highly Inclined and Eccentric Disturber

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Short-term variability of copepod abundance in Jurumirim Reservoir, São Paulo, Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Annual and short-term variability in primary productivity by phytoplankton and correlated abiotic factors in the Jurumirim Reservoir (São Paulo, Brazil)

A variabilidade anual da produção fotossintética (PP) pelo fitoplâncton na zona da barragem da Represa de Jurumirim (São Paulo, Brasil) foi medida após um estudo no período de três anos sucessivos, com o objetivo de identificar padrões recorrentes e suas causas. Medidas da variabilidade da PP em escala diária foram obtidas em dois períodos do ano (estações seca e chuvosa). Nenhum padrão recorrente foi verificado nos dados de PP, visto não haver relação de sua variabilidade com nenhum fator hidrológico (precipitação, nível e vazão de água e washout) nem, aparentemente, com as condições nutritivas da água. A análise de componentes principais revelou que a PP e a taxa de assimilação foram mais elevadas na época do ano em que o conteúdo de PO4(3-) e N-NH4+ foi mais baixo e quando as razões Z EU/Z MIX foram mais elevadas. A produtividade primária/área pode ser estimada pela razão entre a produtividade volumétrica máxima e o coeficiente de extinção vertical da luz. Entretanto, a biomassa integrada na Z EU foi um pobre preditor da produtividade primária/área. Nenhuma correlação foi encontrada entre a temperatura da água com a produtividade primária (por área e volumétrica máxima). em conseqüência, o estudo da PP em três anos sucessivos mostrou que o padrão de variabilidade é tipicamente caótico. em relação às medidas de curta duração, maior PP foi encontrada na estação seca do que na chuvosa. em ambos os períodos, a variabilidade da PP (por área) foi de aproximadamente 35-40%. O padrão foi atribuído não somente à variação na concentração dos nutrientes mas também à magnitude de penetração de luz na água associado ao regime de circulação. Um comentário sobre a relação entre produção primária pelo fitoplâncton com produção pesqueira é também apresentada.