307 research outputs found

    Leibnizian, Galilean and Newtonian structures of spacetime

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    The following three geometrical structures on a manifold are studied in detail: (1) Leibnizian: a non-vanishing 1-form Ω\Omega plus a Riemannian metric \h on its annhilator vector bundle. In particular, the possible dimensions of the automorphism group of a Leibnizian G-structure are characterized. (2) Galilean: Leibnizian structure endowed with an affine connection ∇\nabla (gauge field) which parallelizes Ω\Omega and \h. Fixed any vector field of observers Z (Ω(Z)=1\Omega (Z) = 1), an explicit Koszul--type formula which reconstruct bijectively all the possible ∇\nabla's from the gravitational G=∇ZZ{\cal G} = \nabla_Z Z and vorticity ω=rotZ/2\omega = rot Z/2 fields (plus eventually the torsion) is provided. (3) Newtonian: Galilean structure with \h flat and a field of observers Z which is inertial (its flow preserves the Leibnizian structure and ω=0\omega = 0). Classical concepts in Newtonian theory are revisited and discussed.Comment: Minor errata corrected, to appear in J. Math. Phys.; 22 pages including a table, Late

    Mode resolved density of atmospheric aerosol particles

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    In this study, we investigate the mode resolved density of ultrafine atmospheric particles measured in boreal forest environment. The method used here enables us to find the distinct density information for each mode in atmospheric fine particle population: the density values for nucleation, Aitken, and accumulation mode particles are presented. The experimental data was gained during 2 May 2005–19 May 2005 at the boreal forest measurement station "SMEAR II" in Hyytiälä, Southern Finland. The density values for accumulation mode varied from 1.1 to 2 g/cm<sup>3</sup> (average 1.5 g/cm<sup>3</sup>) and for Aitken mode from 0.4 to 2 g/cm<sup>3</sup> (average 0.97 g/cm<sup>3</sup>). As an overall trend during the two weeks campaign, the density value of Aitken mode was seen to gradually increase. With the present method, the time dependent behaviour of the particle density can be investigated in the time scale of 10 min. This allows us to follow the density evolution of the nucleation mode particles during the particle growth process following the nucleation burst. The density of nucleation mode particles decreased during the growth process. The density values for 15 nm particles were 1.2–1.5 g/cm<sup>3</sup> and for grown 30 nm particles 0.5–1 g/cm<sup>3</sup>. These values are consistent with the present knowledge that the condensing species are semi-volatile organics, emitted from the boreal forest

    Assessment of time limit at lowest speed corresponding to maximal oxygen consumption in the four competitive swimming strokes

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    Time limit at lowest speed of maximal oxygen consumption (TLim-v O2max) was characterized in the 4 swimming strokes, and related with O2max and anaerobic threshold (AnT). 23 elite swimmers performed an incremental protocol for v O2max assessment. 48 hours later, Tlim-v O2max was assessed. O2 was directly measured BxB (K4 b2, Cosmed, Italy) and AnT was assessed individually (YSI 1500L Sport, USA). Tlim-v O2max values were 238.8±39.0, 246.1±51.9, 277.6±85.6 and 331.4±82.7 s in crawl, backstroke, butterfly, and breaststroke (no differences observed). No correlations were found between Tlim-v O2max and O2max, and AnT. However, inverse relationships were observed between Tlim-v O2max and v O2max (r=-0.63, p<0.01) and vAnT (r=-0.52, p=0.01), pointing out that the higher the velocities commonly related to aerobic proficiency, the lower the TLim- v O2max

    Time limit at the minimum velocity of VO2max and intracyclic variation of the velocity of the centre of mass

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    The purpose of this study was to analyse the relationship between time limit at the minimum velocity that elicits maximal oxygen consumption (TLim-vVO2max) and intra-cyclic variations of the velocity of the centre of mass (dv) in the four competitive swimming techniques. Twelve elite male swimmers SWIMMING BIOENERGETICS Rev Port Cien Desp 190 6(Supl.2) 185–197 swam their own best technique until exhaustion at their previously determined v O2max to assess TLim-v O2max. The test was videotaped in the sagittal plan and the APAS software was used to evaluate the horizontal velocity of the centre of mass (Vcm) and its intra-cyclic variation (dv) per swimming technique. Results pointed out that the strokes that presented higher intra-cyclic variations also presented larger values of TLim. Intra-cyclic speed fluctuations (dv) decreased during the TLim test in the four strokes studied, probably due to fatigue. Key words: VO2, intra-cyclic velocity variations, time limit, centre of mass.Authors want to express their gratitude to the Portuguese National Team, and the Portuguese Swimming Federation, for their cooperation

    Interaction between parental psychosis and early motor development and the risk of schizophrenia in a general population birth cohort.

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    BACKGROUND: Delayed motor development in infancy and family history of psychosis are both associated with increased risk of schizophrenia, but their interaction is largely unstudied. AIM: To investigate the association of the age of achieving motor milestones and parental psychosis and their interaction in respect to risk of schizophrenia. METHODS: We used data from the general population-based prospective Northern Finland Birth Cohort 1966 (n=10,283). Developmental information of the cohort members was gathered during regular visits to Finnish child welfare clinics. Several registers were used to determine the diagnosis of schizophrenia among the cohort members and psychosis among the parents. Altogether 152 (1.5%) individuals had schizophrenia by the age of 46 years, with 23 (15.1%) of them having a parent with psychosis. Cox regression analysis was used in analyses. RESULTS: Parental psychosis was associated (P<0.05) with later achievement of holding the head up, grabbing an object, and walking without support. In the parental psychosis group, the risk for schizophrenia was increased if holding the head up (hazard ratio [HR]: 2.46; degrees of freedom [df]=1; 95% confidence interval [95% CI]: 1.07-5.66) and touching the thumb with the index finger (HR: 1.84; df=1; 95% CI: 1.11-3.06) was later. In the group without parental psychosis, a delay in the following milestones increased the risk of schizophrenia: standing without support and walking without support. Parental psychosis had an interaction with delayed touching thumb with index finger (HR: 1.87; df=1; 95% CI: 1.08-3.25) when risk of schizophrenia was investigated. CONCLUSIONS: Parental psychosis was associated with achieving motor milestones later in infancy, particularly the milestones that appear early in a child's life. Parental psychosis and touching the thumb with the index finger had a significant interaction on risk of schizophrenia. Genetic risk for psychosis may interact with delayed development to raise future risk of schizophrenia, or delayed development may be a marker of other risk processes that interact with genetic liability to cause later schizophrenia.This study was supported by grants from the Brain and Behavior Research Foundation, Northern Finland Health Care Support Foundation, Sigrid Jusélius Foundation, and the Signe and Ane Gyllenberg Foundation, Finland. NFBC 1966 received financial support from the Academy of Finland (104781, 120315, 129269, 1114194, 24300796, 268336, 278286), Center of Excellence in Complex Disease Genetics and SALVE, Oulu University Hospital, Oulu, Finland, Biocenter of Oulu, Finland, University of Oulu, Finland (75617, 24002054, 2400692), Ministry of Social Affairs and Health (50459, 50691, 50842, 2749, 2465), NHLBI grant 5R01HL087679-02 through the STAMPEED program (1RL1MH083268-01), NIH/NIMH (5R01MH63706:02), ENGAGE project and grant agreement HEALTH-F4-2007-(201413), EU FP7 EurHEALTHAgeing (277849), EU FP7 EurHealth Epi-Migrant (279143), European Regional Development Fund 537/2010 (24300936) and the Medical Research Council, UK (G0500539, G0600705, G1002319, PrevMetSyn/SALVE).This is the final version of the article. It first appeared from Elsevier via http://dx.doi.org/10.1016/j.eurpsy.2015.04.00

    Future changes in Mekong River hydrology: impact of climate change and reservoir operation on discharge

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    The transboundary Mekong River is facing two ongoing changes that are expected to significantly impact its hydrology and the characteristics of its exceptional flood pulse. The rapid economic development of the riparian countries has led to massive plans for hydropower construction, and projected climate change is expected to alter the monsoon patterns and increase temperature in the basin. The aim of this study is to assess the cumulative impact of these factors on the hydrology of the Mekong within next 20–30 yr. We downscaled the output of five general circulation models (GCMs) that were found to perform well in the Mekong region. For the simulation of reservoir operation, we used an optimisation approach to estimate the operation of multiple reservoirs, including both existing and planned hydropower reservoirs. For the hydrological assessment, we used a distributed hydrological model, VMod, with a grid resolution of 5 km &amp;times; 5 km. In terms of climate change's impact on hydrology, we found a high variation in the discharge results depending on which of the GCMs is used as input. The simulated change in discharge at Kratie (Cambodia) between the baseline (1982–1992) and projected time period (2032–2042) ranges from &amp;minus;11% to &amp;plus;15% for the wet season and &amp;minus;10% to &amp;plus;13% for the dry season. Our analysis also shows that the changes in discharge due to planned reservoir operations are clearly larger than those simulated due to climate change: 25–160% higher dry season flows and 5–24% lower flood peaks in Kratie. The projected cumulative impacts follow rather closely the reservoir operation impacts, with an envelope around them induced by the different GCMs. Our results thus indicate that within the coming 20–30 yr, the operation of planned hydropower reservoirs is likely to have a larger impact on the Mekong hydrograph than the impacts of climate change, particularly during the dry season. On the other hand, climate change will increase the uncertainty of the estimated reservoir operation impacts: our results indicate that even the direction of the flow-related changes induced by climate change is partly unclear. Consequently, both dam planners and dam operators should pay closer attention to the cumulative impacts of climate change and reservoir operation on aquatic ecosystems, including the multibillion-dollar Mekong fisheries

    EC-Earth3-AerChem: A global climate model with interactive aerosols and atmospheric chemistry participating in CMIP6

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    This paper documents the global climate model EC-Earth3-AerChem, one of the members of the EC-Earth3 family of models participating in the Coupled Model Intercomparison Project Phase 6 (CMIP6). EC-Earth3-AerChem has interactive aerosols and atmospheric chemistry and contributes to the Aerosols and Chemistry Model Intercomparison Project (AerChemMIP). In this paper, we give an overview of the model, describe in detail how it differs from the other EC-Earth3 configurations, and outline the new features compared with the previously documented version of the model (EC-Earth 2.4). We explain how the model was tuned and spun up under preindustrial conditions and characterize the model's general performance on the basis of a selection of coupled simulations conducted for CMIP6. The net energy imbalance at the top of the atmosphere in the preindustrial control simulation is on average -0.09 W m-2 with a standard deviation due to interannual variability of 0.25 W m-2, showing no significant drift. The global surface air temperature in the simulation is on average 14.08 ∼ C with an interannual standard deviation of 0.17 ∼ C, exhibiting a small drift of 0.015 ± 0.005 ∼ C per century. The model's effective equilibrium climate sensitivity is estimated at 3.9 ∼ C, and its transient climate response is estimated at 2.1 ∼ C. The CMIP6 historical simulation displays spurious interdecadal variability in Northern Hemisphere temperatures, resulting in a large spread across ensemble members and a tendency to underestimate observed annual surface temperature anomalies from the early 20th century onwards. The observed warming of the Southern Hemisphere is well reproduced by the model. Compared with the ECMWF (European Centre for Medium-Range Weather Forecasts) Reanalysis version 5 (ERA5), the surface air temperature climatology for 1995-2014 has an average bias of -0.86 ± 0.05 ∼ C with a standard deviation across ensemble members of 0.35 ∼ C in the Northern Hemisphere and 1.29 ± 0.02 ∼ C with a corresponding standard deviation of 0.05 ∼ C in the Southern Hemisphere. The Southern Hemisphere warm bias is largely caused by errors in shortwave cloud radiative effects over the Southern Ocean, a deficiency of many climate models. Changes in the emissions of near-term climate forcers (NTCFs) have significant effects on the global climate from the second half of the 20th century onwards. For the SSP3-7.0 Shared Socioeconomic Pathway, the model gives a global warming at the end of the 21st century (2091-2100) of 4.9 ∼ C above the preindustrial mean. A 0.5 ∼ C stronger warming is obtained for the AerChemMIP scenario with reduced emissions of NTCFs. With concurrent reductions of future methane concentrations, the warming is projected to be reduced by 0.5 ∼ C

    Bounce behavior of freshly nucleated biogenic secondary organic aerosol particles

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    The assessment of the climatic impacts and adverse health effects of atmospheric aerosol particles requires detailed information on particle properties. However, very limited information is available on the morphology and phase state of secondary organic aerosol (SOA) particles. The physical state of particles greatly affects particulate-phase chemical reactions, and thus the growth rates of newly formed atmospheric aerosol. Thus verifying the physical phase state of SOA particles gives new and important insight into their formation, subsequent growth, and consequently potential atmospheric impacts. According to our recent study, biogenic SOA particles produced in laboratory chambers from the oxidation of real plant emissions as well as in ambient boreal forest atmospheres can exist in a solid phase in size range &gt;30 nm. In this paper, we extend previously published results to diameters in the range of 17–30 nm. The physical phase of the particles is studied by investigating particle bounce properties utilizing electrical low pressure impactor (ELPI). We also investigate the effect of estimates of particle density on the interpretation of our bounce observations. According to the results presented in this paper, particle bounce clearly decreases with decreasing particle size in sub 30 nm size range. The comparison measurements by ammonium sulphate and investigation of the particle impaction velocities strongly suggest that the decreasing bounce is caused by the differences in composition and phase of large (diameters greater than 30 nm) and smaller (diameters between 17 and 30 nm) particles

    Technical note: Emulation of a large-eddy simulator for stratocumulus clouds in a general circulation model

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    Here we present for the first time a proof of concept for an emulation-based method that uses a large-eddy simulations (LESs) to present sub-grid cloud processes in a general circulation model (GCM). We focus on two key variables affecting the properties of shallow marine clouds: updraft velocity and precipitation formation. The LES is able to describe these processes with high resolution accounting for the realistic variability in cloud properties. We show that the selected emulation method is able to represent the LES outcome with relatively good accuracy and that the updraft velocity and precipitation emulators can be coupled with the GCM practically without increasing the computational costs. We also show that the emulators influence the climate simulated by the GCM but do not consistently improve or worsen the agreement with observations on cloud-related properties, although especially the updraft velocity at cloud base is better captured. A more quantitative evaluation of the emulator impacts against observations would, however, have required model re-tuning, which is a significant task and thus could not be included in this proof-of-concept study. All in all, the approach introduced here is a promising candidate for representing detailed cloud- and aerosol-related sub-grid processes in GCMs. Further development work together with increasing computing capacity can be expected to improve the accuracy and the applicability of the approach in climate simulations.</p

    Analogue peptides for the immunotherapy of human acute myeloid leukemia

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    Accepted manuscript. The final publication is available at: http://link.springer.com/article/10.1007%2Fs00262-015-1762-9The use of peptide vaccines, enhanced by adjuvants, has shown some efficacy in clinical trials. However, responses are often short-lived and rarely induce notable memory responses. The reason is that self-antigens have already been presented to the immune system as the tumor develops, leading to tolerance or some degree of host tumor cell destruction. To try to break tolerance against self-antigens, one of the methods employed has been to modify peptides at the anchor residues to enhance their ability to bind major histocompatibility complex molecules, extending their exposure to the T-cell receptor. These modified or analogue peptides have been investigated as stimulators of the immune system in patients with different cancers with variable but sometimes notable success. In this review we describe the background and recent developments in the use of analogue peptides for the immunotherapy of acute myeloid leukemia describing knowledge useful for the application of analogue peptide treatments for other malignancies
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