136 research outputs found

    The occurrence of Aphanizomenon flos-aquae (Cyanophyceae) in a nutrient gradient in the Baltic

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    The investigation area, Himmerfjarden Bay situated at the Swedish coast of the northern Baltic Proper, receives waste water from a sewage treatment plant. Phosphorus is efficiently reduced in the sewage treatment resulting in a high N : P ratio (≈ 65 : 1) in the discharge. In the near future also the nitrogen discharge will be reduced, and it is teared that a lowered N : P ratio in the receiving waters may favour an undesired increase of nitrogen fixing blue-green algae. This study is focussed on the development of a common nitrogen fixing species in the area, Aphanizomenon flos-aquae, at varied nutrient loadings in 1983-85. The biomass as well as the number of heterocysts was low near the treatment plant and increased with increasing distance from the sewage discharge. The low biomass and number of heterocysts in Himmerfjarden Bay is interpreted as an effect of competition with other algae and of low level of phosphorus relative to nitrogen, i.e. unfavourable conditions for nitrogen fixation. The abundance of Aphanizomenon was highest in 1984 when the phosphorus load was higher than in the other years of investigation. As a tentative conclusion it is suggested that nitrogen fixing algae may increase as a result of reduction in the nitrogen discharge to Himmerfjarden Bay in the future. At the reference station outside the Bay, nutrient conditions favoured nitrogen fixing algae, as interpreted from an inorganic N:P ratio less than 10:1 during the summers of the investigation period. Here the variation in biomass between the years was mainly due to the variaton in water temperature; Aphanizomenon was most abundant during the warm summer of 1984 and less abundant during the cold summer of 1985. A significant correlation was obtained between the heterocyst frequency and concentration of inorganic phosphorus in the trophogenic layer at the reference station

    Investigating the nature of the Fried Egg nebula: CO mm-line and optical spectroscopy of IRAS 17163-3907

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    Through CO mm-line and optical spectroscopy, we investigate the properties of the Fried Egg nebula IRAS 17163-3907, which has recently been proposed to be one of the rare members of the yellow hypergiant class. The CO J=2-1 and J=3-2 emission arises from a region within 20" of the star and is clearly associated with the circumstellar material. The CO lines show a multi-component asymmetrical profile, and an unexpected velocity gradient is resolved in the east-west direction, suggesting a bipolar outflow. This is in contrast with the apparent symmetry of the dust envelope as observed in the infrared. The optical spectrum of IRAS 17163-3907 between 5100 and 9000 {\AA} was compared with that of the archetypal yellow hypergiant IRC+10420 and was found to be very similar. These results build on previous evidence that IRAS 17163-3907 is a yellow hypergiant.Comment: 14 pages including appendix, accepted for publication in A&

    On nitrogen fixation in a coastal area of the northern Baltic

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    Nitrogen (C2H4)-fixation in planktic heterocystous blue-green algae was measured in the Askö area throughout the summer 1976. -Temporal variations in total number of heterocysts, heterocyst frequency, heterocyst activity, acetylene reduction and primary production are discussed. - The amount of nitrogen fixed is estimated to 0.6 gN/m2 x year

    ALMA Compact Array observations of the Fried Egg nebula: Evidence for large-scale asymmetric mass-loss from the yellow hypergiant IRAS 17163-3907

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    Yellow hypergiants are rare and represent a fast evolutionary stage of massive evolved stars. That evolutionary phase is characterised by a very intense mass loss, the understanding of which is still very limited. Here we report ALMA Compact Array observations of a 50""-mosaic toward the Fried Egg nebula, around one of the few Galactic yellow hypergiants IRAS 17163-3907. The emission from the 12^{12}CO J=2-1 line, H30α\alpha recombination line, and continuum is imaged at a resolution of \sim8"", revealing the morphology of the molecular environment around the star. The continuum emission is unresolved and peaks at the position of the star. The radio recombination line H30α\alpha shows unresolved emission at the star, with an approximately gaussian spectrum centered on a velocity of 21±\pm3~km/s with a width of 57±\pm6~km/s. In contrast, the CO 2-1 emission is complex and decomposes into several components beyond the contamination from interstellar gas in the line of sight. The CO spectrum toward the star is a broad plateau, centered at the systemic velocity of +18 km/s and with an expansion velocity of 100±\pm10 km/s. Assuming isotropic and constant mass-loss, we estimate a mass-loss rate of 8±\pm1.5 ×105\times10^{-5}~M_\odot yr1^{-1}. At a radius of 25"" from the star, we detect CO emission associated with the dust ring previously imaged by {\it Herschel}. The kinematics of this ring, however, is not consistent with an expanding shell, but show a velocity gradient of vsys±v_{sys} \pm20 km/s. In addition, we find a puzzling bright feature radially connecting the star to the CO ring, at a velocity of +40 km/s relative to the star. This spur feature may trace a unidirectional ejection event from the star. Our ACA observations reveal the complex morphology around IRAS 17163 and illustrate the breakthroughs that ALMA will bring to the field of massive stellar evolution

    Intake of individual fatty acids and risk of prostate cancer in the European prospective investigation into cancer and nutrition

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    The associations of individual dietary fatty acids with prostate cancer risk have not been examined comprehensively. We examined the prospective association of individual dietary fatty acids with prostate cancer risk overall, by tumor subtypes, and prostate cancer death. 142,239 men from the European Prospective Investigation into Cancer and Nutrition who were free from cancer at recruitment were included. Dietary intakes of individual fatty acids were estimated using center-specific validated dietary questionnaires at baseline and calibrated with 24-hour recalls. Multivariable Cox regression models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). After an average follow-up of 13.9 years, 7,036 prostate cancer cases and 936 prostate cancer deaths were ascertained. Intakes of individual fatty acids were not related to overall prostate cancer risk. There was evidence of heterogeneity in the association of some short chain saturated fatty acids with prostate cancer risk by tumor stage (Pheterogeneity <0.015), with a positive association with risk of advanced stage disease for butyric acid (4:0; HR1SD =1.08; 95%CI=1.01-1.15; P-trend=0.026). There were no associations with fatal prostate cancer, with the exception of a slightly higher risk for those who consumed more eicosenoic acid (22:1n-9c; HR1SD =1.05; 1.00-1.11; P-trend=0.048) and eicosapentaenoic acid (20:5n-3c; HR1SD =1.07; 1.00-1.14; P-trend=0.045). There was no evidence that dietary intakes of individual fatty acids were associated with overall prostate cancer risk. However, a higher intake of butyric acid might be associated with a higher risk of advanced, whereas intakes of eicosenoic and eicosapentaenoic acids might be positively associated with fatal prostate cancer risk. This article is protected by copyright. All rights reserved

    Protein supplementation in strength and conditioning adepts: knowledge, dietary behaviour and practice in Palermo, Italy

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    Background: It is known that supplement use is a widespread and accepted practice by athletes and people who attend commercial gyms. Little is known about protein supplement amongst people undertaking strength training in commercial gyms in Italy when compared to the US. Objective: The purpose of this study was to examine the use of protein supplementation, alone or in association with other supplements, and dietary behavior amongst regular fitness center attendees in Palermo, Italy. Design: Resistance training information have been collected from 800 regular fitness center attendees for the initial analysis. A specific questionnaire was generated for the experimentation. Data were collected using a face-to-face interview method. Supplement users were then compared to the non users and analyzed using a one-way ANOVA, Kruskall-Wallis, chi-square test or exact test of Fisher when appropriate. Results: 30.1% of the respondents use dietary supplements during their training as a believe it is the "way to gain muscles and strength". Whey protein shakes (50.0%) mixed with creatine and amino-acids (48.3%) were the most frequent choices amongst the users. A majority of the subjects (34.0%) appeared to rely on their gym instructors' advice for their intake; a lower proportion (13.0%) consulted physicians, while none of them consulted nutritionists. A high consumption of milk has been noticed in both users (67,7%) and non-users (52,8%); supplement non-users consumed significantly more snacks and bakery products than users per week (P < 0.001), while users consumed significantly more protein-rich foods (P < 0.01) with a particular preference for meat (48.0%). Conclusions: A considerable number of regular strength training adepts consume protein supplements mixed with other products (mainly creatine and amino-acids). Limited numbers consult "dietary specialists" and rely mainly on their instructors. We emphasize on the importance of the dissemination of scientifically based information about supplementation in this environment and the promotion of updated educational programs for the instructors

    The VLT/SPHERE view of the ATOMIUM cool evolved star sample. I. Overview:Sample characterization through polarization analysis

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    Aims. Through the ATOMIUM project, based on an ALMA large program, we aim to present a consistent view of a sample of 17 nearby cool evolved stars (Aymptotic Giant Branch and red supergiant stars). Methods. Here we present VLT/SPHERE-ZIMPOL polarimetric maps obtained in the visible of 14 out of the 17 ATOMIUM sources. They were obtained contemporaneously with the ALMA high spatial resolution data. To help interpret the polarized signal, we produced synthetic maps of light scattering by dust, through 3D radiative transfer simulations with the RADMC3D code. Results. The degree of linear polarization (DoLP) observed by ZIMPOL spreads across several optical filters. We infer that it primarily probes dust located just outside of the point spread function, and in or near the plane of the sky, with a total optical depth close to unity in the line of sight, representing only a fraction of the total circumstellar dust. The maximum DoLP ranges from 0.03-0.38 depending on the source, fractions that can be reproduced by our 3D pilot models for grains composed of common dust species. The spatial structure of the DoLP shows a diverse set of shapes. Only for three sources do we note a correlation between the ALMA CO and SiO lines, which trace the gas density, and the DoLP, which traces the dust. Conclusion. The clumpiness of the DoLP and the lack of a consistent correlation between the gas and the dust location show that, in the inner circumstellar environment (CSE), dust formation occurs at very specific sites. This has potential consequences for the derived mass-loss rates and dust-to-gas ratio in the inner region of the CSE. Except for π1\pi^1~Gru and perhaps GY Aql, we do not detect interactions between the circumstellar wind and the hypothesized companions that shape the wind at larger scales. This suggests that the orbits of any other companions are tilted out of the plane of the sky.Comment: Accepted for publication in Astronomy & Astrophysics. 22 pages, 15 figures, 5 table

    The VLT/SPHERE view of the ATOMIUM cool evolved star sample. I. Overview: Sample characterization through polarization analysis

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    Aims. Through the ATOMIUM project, based on an ALMA large program, we aim to present a consistent view of a sample of 17 nearby cool evolved stars (Aymptotic Giant Branch and red supergiant stars). Methods. Here we present VLT/SPHERE-ZIMPOL polarimetric maps obtained in the visible of 14 out of the 17 ATOMIUM sources. They were obtained contemporaneously with the ALMA high spatial resolution data. To help interpret the polarized signal, we produced synthetic maps of light scattering by dust, through 3D radiative transfer simulations with the RADMC3D code. Results. The degree of linear polarization (DoLP) observed by ZIMPOL spreads across several optical filters. We infer that it primarily probes dust located just outside of the point spread function, and in or near the plane of the sky, with a total optical depth close to unity in the line of sight, representing only a fraction of the total circumstellar dust. The maximum DoLP ranges from 0.03-0.38 depending on the source, fractions that can be reproduced by our 3D pilot models for grains composed of common dust species. The spatial structure of the DoLP shows a diverse set of shapes. Only for three sources do we note a correlation between the ALMA CO and SiO lines, which trace the gas density, and the DoLP, which traces the dust. Conclusion. The clumpiness of the DoLP and the lack of a consistent correlation between the gas and the dust location show that, in the inner circumstellar environment (CSE), dust formation occurs at very specific sites. This has potential consequences for the derived mass-loss rates and dust-to-gas ratio in the inner region of the CSE. Except for π1\pi^1~Gru and perhaps GY Aql, we do not detect interactions between the circumstellar wind and the hypothesized companions that shape the wind at larger scales. This suggests that the orbits of any other companions are tilted out of the plane of the sky.Comment: Accepted for publication in Astronomy & Astrophysics. 22 pages, 15 figures, 5 table
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