| 741. |
- Vinterstare, Jerker, et al.
(författare)
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Sex matters : predator presence induces sexual dimorphism in a monomorphic prey, from stress genes to morphological defences
- 2023
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Ingår i: Evolution; international journal of organic evolution. - : Oxford University Press (OUP). - 1558-5646. ; 77:1, s. 304-317
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Tidskriftsartikel (refereegranskat)abstract
- Inducible defences allow prey to increase survival chances when predators are present while avoiding unnecessary costs in their absence. Many studies report considerable inter-individual variation in inducible defence expression, yet what underlies this variation is poorly understood. A classic vertebrate example of a predator-induced morphological defence is the increased body depth in crucian carp (Carassius carassius), which reduces the risk of predation from gape-size limited predators. Here, we report that among-individual variation in morphological defence expression can be linked to sex. We documented sexual dimorphism in lakes in which crucian carp coexisted with predators, where females showed shallower relative body depths than males, but not in a predator-free lake. When exposing crucian carp from a population without predators to perceived predation risk in a laboratory environment (presence/absence of pike, Esox lucius), we found that males expressed significantly greater morphological defence than females, causing sexual dimorphism only in the presence of predators. We uncovered a correlative link between the sex-specific inducible phenotypic response and gene expression patterns in major stress-related genes (POMC, MC3R, and MC4R). Together, our results highlight that sex-specific responses may be an important, yet underappreciated, component underlying inter-individual differences in the expression of inducible defences, even in species without pronounced sexual dimorphism.
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| 742. |
- Viola, N., et al.
(författare)
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H2020 STRATOFLY PROJECT : FROM EUROPE TO AUSTRALIA IN LESS THAN 3 HOURS
- 2021
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Ingår i: 32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021. - 9783932182914
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Konferensbidrag (refereegranskat)abstract
- As eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable high-speed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and green-house gases, particularly during stratospheric cruise. However, only a dedicated multi-disciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. This paper aims at summarizing the main results achieved so far to solve the main issues related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors.
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| 743. |
- Viola, Nicole, et al.
(författare)
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Stratofly mr3 – how to reduce the environmental impact of high-speed transportation
- 2021
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Ingår i: AIAA Scitech 2021 Forum. - 9781624106095 ; , s. 1-21
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Konferensbidrag (refereegranskat)abstract
- This paper addresses the main progresses and achievements of the H2020 STRATOFLY Project, funded by the European Commission, under the Horizon 2020 framework, specifically looking at the latest results in terms of environmental sustainability. In particular, starting from reporting the main environmental challenges posed by high-speed civil transportation, at local, regional and global levels, this paper describes the way in which the STRATOFLY MR3 vehicle, a Mach 8 waverider fueled with liquid hydrogen, promises to limit the overall environmental impact. In details, firstly, the paper describes some of the main technological improvements adopted to reduce the aircraft emission and then it reports about the status of the numerical and experimental test campaigns on the high-speed engine, showing the results achieved so far. This preliminary emission inventory allows for the evaluation of emission indexes throughout the mission profile, the verification of the compliance with the ICAO prescriptions, the estimation of the impact on air quality and climate and eventually, when necessary, the paper proposes adequate mitigation actions.
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| 744. |
- Vogt, Matthias, et al.
(författare)
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Heated submicron particle fluxes using an optical particle counter in urban environment
- 2013
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 13:6, s. 3087-3096
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Tidskriftsartikel (refereegranskat)abstract
- From May 2008 to March 2009 aerosol emissions were measured using the eddy covariance method covering the size range 0.25 to 2.5 mu m diameter (D-p) from a 105m tower, in central Stockholm, Sweden. Supporting chemical aerosol data were collected at roof and street level. Results show that the inorganic fraction of sulfate, nitrate, ammonium and sea salt accounts for approximately 15% of the total aerosol mass < 1 mu m D-p (PM1) with water soluble soil contributing 11% and water insoluble soil 47%. Carbonaceous compounds were at the most 27% of PM1 mass. It was found that heating the air from the tower to 200 degrees C resulted in the loss of approximately 60% of the aerosol volume at 0.25 mu m D-p whereas only 40% of the aerosol volume was removed at 0.6 mu m D-p. Further heating to 300 degrees C caused very little additional losses < 0.6 mu m D-p. The chemical analysis did not include carbonaceous compounds, but based on the difference between the total mass concentration and the sum of the analyzed non-carbonaceous materials, it can be assumed that the non-volatile particulate material (heated to 300 degrees C) consists mainly of carbonaceous compounds, including elemental carbon. Furthermore, it was found that the nonvolatile particle fraction < 0.6 mu m D-p correlated (r(2) = 0.4) with the BC concentration at roof level in the city, supporting the assumption that the non-volatile material consists of carbonaceous compounds. The average diurnal cycles of the BC emissions from road traffic (as inferred from the ratio of the incremental concentrations of nitrogen oxides (NOx) and BC measured on a densely trafficked street) and the fluxes of non-volatile material at tower level are in close agreement, suggesting a traffic source of BC. We have estimated the emission factors (EFs) for non-volatile particles < 0.6 mu m D-p to be 2.4 +/- 1.4 mg veh(-1) km(-1) based on either CO2 fluxes or traffic activity data. Light (LDV) and heavy duty vehicle (HDV) EFs were estimated using multiple linear regression and reveal that for non-volatile particulate matter in the 0.25 to 0.6 mu m D-p range, the EFHDV is approximately twice as high as the EFLDV, the difference not being statistically significant.
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| 745. |
- Vogt, Matthias, et al.
(författare)
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Seasonal and diurnal cycles of 0.25–2.5 μm aerosol fluxes over urban Stockholm, Sweden
- 2011
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Ingår i: Tellus. Series B, Chemical and physical meteorology. - : Stockholm University Press. - 0280-6509 .- 1600-0889. ; 63:5, s. 935-951
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Tidskriftsartikel (refereegranskat)abstract
- Size resolved aerosol and gas fluxes were measured in Stockholm from 1 April 2008 to 15 April 2009 over both urban and green sectors. CO2 and H2O fluxes peaked in daytime for all seasons. CO2 concentrations peaked in winter. Due to vegetation influence the CO2 fluxes had different diurnal cycles and magnitude in the two sectors. In the urban sector, CO2 fluxes indicated a net source. The sector dominated by residential areas and green spaces had its highest aerosol fluxes in winter. In spring, super micrometer concentrations for both sectors were significantly higher, as were the urban sector rush hour fluxes. The submicrometer aerosol fluxes had a similar diurnal pattern with daytime maxima for all seasons. This suggests that only the super micrometer aerosol emissions are dependent on season. During spring there was a clear difference in super micrometer fluxes between wet and dry streets. Our direct flux measurements have improved the understanding of the processes behind these aerosol emissions. They support the hypothesis that the spring peak in aerosol emissions are due to road dust, produced during the winter, but not released in large quantities until the roads dry up during spring, and explain why Stockholm has problems meeting the EU directive for aerosol mass (PM10).
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| 746. |
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| 747. |
- Vogt, Matthias, et al.
(författare)
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The relationship between 0.25-2.5 mu m aerosol and CO2 emissions over a city
- 2011
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Ingår i: Atmospheric Chemistry And Physics. - : Copernicus GmbH. - 1680-7316 .- 1680-7324. ; 11:10, s. 4851-4859
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Tidskriftsartikel (refereegranskat)abstract
- Unlike exhaust emissions, non-exhaust traffic emissions are completely unregulated and in addition, there are large uncertainties in the non-exhaust emission factors required to estimate the emissions of these aerosols. This study provides the first published results of direct measurements of size resolved emission factors for particles in the size range 0.25-2.5 mu m using a new approach to derive aerosol emission factors based on carbon dioxide (CO2) emission fluxes. Aerosol fluxes were measured over one year using the eddy covariance method at the top of a 105m high communication tower in Stockholm, Sweden. Maximum CO2 and particle fluxes were found when the wind direction coincided with the area of densest traffic within the footprint area. Negative fluxes (uptake of CO2 and deposition of particles) coincided with periods of sampling from an urban forest area. The fluxes of CO2 were used to obtain emission factors for particles by assuming that the CO2 fluxes could be directly related to the amount of fuel burnt by vehicles in the footprint area. The estimated emission factor for the fleet mix in the measurement area was, in number 1.8 x 10(11) particle veh(-1) km(-1) (for 0.25-2.5 mu m size range). Assuming spherical particles of density 1600 kg m(-3) this corresponds to 27.5 mg veh(-1) km(-1). For particles (0.8-2.5 mu m) the emission factors were 5.1 x 10(9) veh(-1) km(-1) for number and 11.5 mg veh(-1) km(-1) for mass. But a wind speed dependence was noted for high wind speeds. Thus, for wind speeds larger than 9 ms(-1), as measured in the tower at 105m (U-105), the emission factor for particle number and mass was parameterised as: E-f(Number, 0.8-2.5 mu m) = (6.1 +/- 1.7)10(9)U(105)-50+/-188 and E-f(Mass, 0.8-2.5 mu m) = (20+/-12)U-105-171+/-122.
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| 748. |
- Vogt, Matthias, et al.
(författare)
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Traffic Aerosol emission velocity derived from direct flux measurements over urban Stockholm, Sweden
- 2011
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310 .- 1873-2844. ; 45:32, s. 5725-5731
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Tidskriftsartikel (refereegranskat)abstract
- Size-resolved aerosol vertical number fluxes were measured using the eddy covariance method, 105 meters above the ground over the city of Stockholm, Sweden, between 1st April 2008 and 15th April 2009. The size range of the measurements cover particles from 0.25 to 2.5 μm diameter (Dp). Emission velocities (ve) were calculated for the same size range and were found to be well correlated with friction velocity (u*) and CO2 fluxes (FCO2). These variables were used to parameterize the emission velocity aswhere ve and u* are given in [m s−1], Dp in [μm], and FCO2 in [mmol m−2s−1]. The parameterization reproduces the average diurnal cycle from the observations well for particles sizes up to 0.6 μm Dp. For larger particles the parameterization tends to over predict the emission velocity. These larger particles are not believed to be produced by combustion and therefore not well represented by FCO2, which represents the traffic source through its fossil fuel consumption and the related CO2 emissions.
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| 749. |
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| 750. |
- von Wachenfelt, Hans, et al.
(författare)
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Beräkningsunderlag för dimensionering av plansiloväggar
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Det finns idag ingen gällande standard för plansiloväggar för ensilage. Nuvarande beräkningar och konstruktionsutförande baseras på tidigare framtagna anvisningar (JBR). Dessa var avsedda för användning vid konstruktion av silovägghöjder om max 3m. Det fanns anledning att tro att dessa anvisningar överskattar krafterna och trycken, i huvudsak från pressvatten, som inträffar speciellt för siloväggar högre än 3 m. Detta kan resultera i överdimensionering, materialslöseri och ökade investeringskostnader. Det övergripande målet med projektet var att bestämma ensilagets fysikaliska egenskaper som har betydelse för det horisontella väggtrycket och bestämma maximala pressvattentrycket hos silor med en vägghöjd om 3 m eller högre. Dataunderlaget skulle utgöra grunden för utarbetande av nya beräknings- och konstruktionsanvisningar och en reviderad svensk standard. Målet var att minska investeringskostnaden för ensilagesilor. Pressvattennivån mättes med hjälp av en mätsticka i 16 mm stålrör och mätstege, vilka var placerade vertikalt längs siloväggens insida. Pressvattenmätningar utfördes under två säsonger i 24 silor, medan tryckprofiler mot siloväggen mättes vid inläggning av 10 gräs- och majsskördar under en säsong, med ungefär 400 tryckprofiler vid varje inläggning. En tryckprofil av det horisontella väggtrycket erhölls genom att lastgivare monterades på mätstegarna. Trycket mot lastgivarna registrerades genom ett datainsamlingssystem som visade statisk och total last (tryck utövat av ensilagemassan och packningsmaskinen). De statiska lasterna registrerades utan överfart av packningsmaskin och totaltrycken registrerades då en packningsmaskin passerade lastgivarna på mätstegarna. Skillnaden mellan den statiska och den totala lasten definierades som den dynamiska lasten. Resultaten visar att pressvattennivån varierar avsevärt mellan skördar inom gården på grund av väderlek och geografisk placering i Sverige. Medelvärdet av 24 maximalt uppmätta pressvattennivåer var 40 % av silohöjden. I en odränerad silo kvarstod pressvattennivån under lagringen. Pressvattennivån i silorna ökad väggtrycket 2 månader efter inläggning med ca 30 %, men pressvattennivåns inverkan på väggtrycket var endast statistiskt påvisbart 1 m från silobotten. Det statiska väggtrycket uppgick till 16 kPa vid inläggning respektive 22 kPa två månader efter inläggning i botten av silorna. Pressvattnet inverkade endast efter inläggning och samverkade inte med packmaskinen. Den dynamiska lasten angrep 0,5-1 m under ensilageytan mot siloväggen med ca 17 kPa vid en däcksbredd om 0,5 m och maskinvikt om 11,2 - 14,5 ton då fordonet kördes 0,1 m från siloväggen. I avsnittet Ny Standard redogörs för hur det nya beräkningsförfarandet har tagits fram baserat på ovanstående mätresultat och normer från Eurokod både för Brottgräns och Bruksgränstillstånd. I avsnittet jämförs dimensionerande moment baserat på äldre och nytt förslag till beräkningsförfarande. Vid inläggning i 4 m silo blir dimensionerande moment för packningsmaskin som huvudlast medan ensilaget som huvudlast blir dimensionerande för de lägre delarna av siloväggen i bruksskedet. Slutsats för Brottgräns- respektive Bruksgränstillstånd är att det dimensionerande momentet för 4 m plansilo beräknat enligt Eurokod blev 21 resp 15 % mindre än motsvarande beräkning enligt JBR. Det nya förslaget innehåller även krav på max sprickvidd om 0,3 mm för betongsilor. Vid dimensionering ska även hänsyn tas till grundläggning och olyckslast.
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