scholarly journals The impact of free convection on late morning ozone decreases on an Alpine foreland mountain summit

2008 ◽  
Vol 8 (2) ◽  
pp. 5437-5476
Author(s):  
J.-C. Mayer ◽  
K. Staudt ◽  
S. Gilge ◽  
F. X. Meixner ◽  
T. Foken
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Mixing Ratio ◽  
Tethered Balloon ◽  
Diurnal Course ◽  
Alpine Foreland ◽  
Mountain Summit ◽  
The Impact

Abstract. Exceptional patterns in the diurnal course of ozone mixing ratio at a mountain top site (998 m a.s.l.) were observed during a field experiment (September 2005). They manifested themselves as strong and sudden decreases of ozone mixing ratio levels with a subsequent return to previous levels. Considering corresponding long-term time series (2000–2005) it was found, that such events occur mainly during summer, and affect the mountain top site in about 18% of the summer days. Combining (a) surface layer measurements at mountain summit and at the foot of the mountain, (b) in-situ (tethered balloon) and remote sensing (SODAR-RASS) measurements within the atmospheric boundary layer, the origin of these events of sudden ozone decrease could be attributed to free convection, triggered by a rather frequently occurring wind speed minimum around the location of the mountain.

scholarly journals The impact of free convection on late morning ozone decreases on an Alpine foreland mountain summit

2008 ◽  
Vol 8 (19) ◽  
pp. 5941-5956 ◽  
Author(s):  
J.-C. Mayer ◽  
K. Staudt ◽  
S. Gilge ◽  
F. X. Meixner ◽  
T. Foken
Keyword(s):  
Boundary Layer ◽  
Free Convection ◽  
Mixing Ratio ◽  
Tethered Balloon ◽  
Diurnal Course ◽  
Alpine Foreland ◽  
Mountain Summit ◽  
The Impact

Abstract. Exceptional patterns in the diurnal course of ozone mixing ratio at a mountain top site (998 m a.s.l.) were observed during a field experiment (September 2005). They manifested themselves as strong and sudden decreases of ozone mixing ratio with a subsequent return to previous levels. The evaluation of corresponding long-term time series (2000–2005) revealed that such events occur mainly during summer, and affect the mountain top site on about 18% of the summer days. Combining (a) surface layer measurements at mountain summit and at the foot of the mountain, (b) in-situ (tethered balloon) and remote sensing (SODAR-RASS) measurements within the atmospheric boundary layer, the origin of these events of sudden ozone decrease could be attributed to free convection. The free convection was triggered by a rather frequently occurring wind speed minimum around the location of the mountain.

The Use of Laboratory-Measured and Strain-Gauge Backcalculated Asphalt Stiffness for Rutting Performance Prediction

2019 ◽  
Vol 2673 (3) ◽  
pp. 323-333
Author(s):  
Erdem Coleri ◽  
John T. Harvey
Keyword(s):  
Performance Prediction ◽  
Strain Gauge ◽  
Asphalt Concrete ◽  
Laboratory Tests ◽  
Concrete Materials ◽  
Long Term Performance ◽  
Term Performance ◽  
The Impact

Laboratory tests are conducted with asphalt concrete materials to determine the expected in-situ performance. In addition, laboratory test results are commonly used in mechanistic-empirical design methods for material characterization to improve the predictive accuracy of the models. However, the effectiveness of laboratory tests in characterizing the long-term performance of asphalt concrete materials needs to be validated to be able to use the results for pavement design and long-term performance prediction. Inaccurate performance characterization and prediction can directly affect the decision-making process for pavement maintenance, rehabilitation, and reconstruction and result in unexpected early failures in the field. The major objective of this study is to determine the impact of using laboratory-measured asphalt stiffness on the prediction accuracy of mechanistic-empirical models. In addition, the effect of using linear-elastic modeling assumptions (layered elastic theory) and neglecting the nonlinearity of pavement response at high load levels (and/or at high strain levels for weaker structures) on the predicted rutting performance was determined. In this study, the effectiveness of the use of laboratory asphalt stiffness tests for in-situ asphalt stiffness characterization was determined by comparing the rutting performance predicted using laboratory-measured stiffness to rutting predicted using strain-gauge backcalculated stiffness. It was determined that laboratory tests are able to characterize the in-situ stiffness characteristics of the asphalt mix used in this study and the stiffness characterization process suggested in this study can provide reliable rutting performance predictions. Results of this study are only applicable to tested rubberized asphalt concrete mixtures.

Belastung von Patienten und Gesundheitssystem durch Pleuraverweildrainage zur Versorgung chronischer Pleuraergüsse

2019 ◽  
Vol 7 (2) ◽  
pp. 84-85
Author(s):  
Axel Tobias Kempa
Keyword(s):  
Length Of Hospital Stay ◽  
Chest Drain ◽  
Long Term Outcomes ◽  
Talc Pleurodesis ◽  
In Situ Methods ◽  
Hospital Visits ◽  
The Impact

Background: Indwelling pleural catheters (IPC) offer an alternative to talc pleurodesis in recurrent effusion, especially in patients wishing to avoid hospitalization. Two randomized trials have demonstrated reduced time in hospital using IPCs versus talc pleurodesis in malignant pleural effusion (MPE). However, the impact of IPCs on hospital services and patients has not been well studied. Objectives: To analyze long-term outcomes of IPCs and understand the hospital burden in terms of requirement for hospital visits and contacts with healthcare, while the IPC was in situ. Methods: IPC insertions in a tertiary pleural center were analyzed retrospectively. Reviews of patients with IPCs in situ considered «additional» to routine clinical follow-up were defined pre-hoc. Results: A total of 202 cases were analyzed: 89.6% MPE group (n = 181) and 10.4% non-MPE group (n = 21). There were a median 3.0 (interquartile range [IQR] 3) and 2.0 (IQR 2) ipsilateral pleural procedures prior to each IPC insertion in non-MPE and MPE groups, respectively (p = 0.26), and a mean 1.3 (SD 1.7) planned IPC-related outpatient follow-up visits per patient. There were 2 (9.5%) and 14 (7.7%) IPC-related infections in non-MPE and MPE groups, respectively. Four (19.0%) and 44 (24.3%) patients required additional IPC-related reviews in non-MPE and MPE groups, respectively (p = 0.6), and these occurred within 250 days post IPC insertion. Conclusions: Although IPCs decrease initial length of hospital stay compared to talc pleurodesis via chest drain, IPCs are associated with significant hospital-visit burden, in addition to planned visits and regular home IPC drainages. IPC-using services need to be prepared for this additional work to run an IPC service effectively.

scholarly journals Intercomparison of in situ water vapor balloon-borne measurements from Pico-SDLA H<sub>2</sub>O and FLASH-B in the tropical UTLS

2015 ◽  
Vol 8 (12) ◽  
pp. 13693-13727
Author(s):  
M. Ghysels ◽  
E. D. Riviere ◽  
S. Khaykin ◽  
C. Stoeffler ◽  
N. Amarouche ◽  
...  
Keyword(s):  
Water Vapor ◽  
Low Cost ◽  
Deep Convection ◽  
Mixing Ratio ◽  
Stratospheric Water Vapor ◽  
In Situ Techniques ◽  
Scientific Project ◽  
Water Vapor Mixing Ratio ◽  
The Impact

Abstract. In this paper we compare water vapor mixing ratio measurements from two quasi-parallel flights of the Pico-SDLA H2O and FLASH-B hygrometers. The measurements were made on 10 February 2013 and 13 March 2012, respectively, in the tropics near Bauru, Sao Paulo St., Brazil during an intense convective period. Both flights were performed as part of a French scientific project, TRO-Pico, to study the impact of the deep-convection overshoot on the water budget. Only a few instruments that permit the frequent sounding of stratospheric water vapor can be flown within a small volume weather balloons. Technical difficulties preclude the accurate measurement of stratospheric water vapor with conventional in situ techniques. The instruments described here are simple and lightweight, which permits their low-cost deployment by non-specialists aboard a small weather balloon. We obtain mixing ratio retrievals which agree above the cold-point tropopause to within 1.9 and 0.5 % for the first and second flights, respectively. This level of agreement for measured stratospheric water mixing ratio is among the best ever reported in the literature. Because both instruments show similar profiles within their combined uncertainties, we conclude that the Pico-SDLA H2O and FLASH-B datasets are mutually consistent.

scholarly journals Measurement report: Vertical profiling of particle size distributions over Lhasa, Tibet: Tethered balloon-based in-situ measurements and source apportionment

2021 ◽  
Author(s):  
Liang Ran ◽  
Zhaoze Deng ◽  
Yunfei Wu ◽  
Jiwei Li ◽  
Zhixuan Bai ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Particle Size ◽  
Source Apportionment ◽  
Particle Mass ◽  
Size Distributions ◽  
Aerosol Formation ◽  
Tethered Balloon ◽  
Particle Size Distributions ◽  
Secondary Aerosol

Abstract. In-situ measurements of vertically resolved particle size distributions based on a tethered balloon system were carried out for the first time in the highland city of Lhasa over the Tibetan Plateau in summer 2020, using portable optical counters for the size range of 0.124~32 μm. The vertical structure of 112 aerosol profiles was found to be largely shaped by the evolution of the boundary layer (BL), with a nearly uniform distribution of aerosols within the daytime mixing layer and a sharp decline with the height in the shallow nocturnal boundary layer. During the campaign, the average mass concentration of particulate matters smaller than 2.5 μm in aerodynamic diameter (PM2.5) within the BL was around 3 μg m−3, almost four times of the amount in the free troposphere (FT), which was rarely affected by surface anthropogenic emissions. Though there was a lower level of particle mass in the residual layer (RL) than in the BL, a similarity in particle mass size distributions (PMSDs) suggested that particles in the RL might be of the same origin as particles in the BL. This was also in consistence with the source apportionment analysis based on the PMSDs. Three distinct modes were observed in the PMSDs for the BL and the RL. One mode was exclusively coarse particles up to roughly 15 μm and peaked around 5 μm. More than 50 % of total particle mass was often contributed by coarse mode particles in this area, which was thought to be associated with local dust resuspension. The mode peaking over 0.5~0.7 μm was representative of biomass burning on religious holidays and was found to be most pronounced on holiday mornings. The contribution from the religious burning factor rose from about 25 % on non-holidays to nearly 50 % on holiday mornings. The mode dominated by particles smaller than 0.3 μm was thought to be associated with combustion related emissions and/or secondary aerosol formation. In the FT coarse mode particles only accounted for less than 10 % of the total mass and particles larger than 5 μm were negligible. The predominant submicron particles in the FT might be related to secondary aerosol formation and the aging of existed particles. To give a full picture of aerosol physical and chemical properties and better understand the origin and impacts of aerosols in this area, intensive field campaigns involving measurements of vertically resolved aerosol chemical compositions in different seasons would be much encouraged in the future.

scholarly journals Homologous chromosomes in asexual rotifer Adineta vaga suggest automixis

2020 ◽  
Author(s):  
Paul Simion ◽  
Jitendra Narayan ◽  
Antoine Houtain ◽  
Alessandro Derzelle ◽  
Lyam Baudry ◽  
...  
Keyword(s):  
Genome Assembly ◽  
Genome Structure ◽  
Meiotic Pairing ◽  
Chromosome Conformation ◽  
Homologous Chromosomes ◽  
Ancient Asexual ◽  
High Doses ◽  
The Impact

ABSTRACTThe several hundreds of species of bdelloid rotifers are notorious because they represent an ancient clade comprising only asexual lineages1. Moreover, most bdelloid species have the ability to withstand complete desiccation and high doses of ionizing radiation, being able to repair their DNA after massive genome breakage2. To better understand the impact of long-term asexuality and DNA breakage on genome evolution, a telomere-to-tolemere reference genome assembly of a bdelloid species is critical3, 4. Here we present the first, high quality chromosome-scale genome assembly for the bdelloid A. vaga validated using three complementary assembly procedures combined with chromosome conformation capture (Hi-C) data. The different assemblies reveal the same genome architecture and using fluorescent in situ hybridization (FISH), we demonstrate that the A. vaga genome is composed of six pairs of homologous chromosomes, compatible with meiosis. Moreover, the synteny between homoeologous (or ohnologous) chromosomes is also preserved, confirming their paleotetraploidy. The diploid genome structure of A. vaga and the presence of very long homozygous tracts show that recombination between homologous chromosomes occurs in this ancient asexual scandal, either during DSB repair or during meiotic pairing. These homozygosity tracts are mainly observed towards the chromosome ends in the clonal A. vaga suggesting signatures of a parthenogenetic mode of reproduction equivalent to central fusion automixis, in which homologous chromosomes are not segregated during the meiotic division.

scholarly journals Using a holographic imager on a tethered balloon system for microphysical observations of boundary layer clouds

2019 ◽  
Author(s):  
Fabiola Ramelli ◽  
Alexander Beck ◽  
Jan Henneberger ◽  
Ulrike Lohmann
Keyword(s):  
Boundary Layer ◽  
Cloud Droplet ◽  
Sample Volume ◽  
Tethered Balloon ◽  
Wind Speeds ◽  
Boundary Layer Clouds ◽  
Cloud Properties ◽  
Main Component ◽  
Balloon System

Abstract. Conventional techniques to measure boundary layer clouds such as research aircrafts are unable to sample in orographic or densely-populated areas. In this paper, we present a newly developed measurement platform on a tethered balloon system (HoloBalloon) to measure in situ vertical profiles of microphysical and meteorological cloud properties up to 1 kilometer above ground. The main component of the HoloBalloon platform is a holographic imager, which uses digital in-line holography to image cloud particles in a velocity independent sample volume, making it particularly well suited for measurements on a balloon. The unique combination of holography and balloon-borne measurements allows observations with high spatial resolution, covering cloud structures from the kilometer down to the millimeter scale. We present observations of a supercooled low stratus cloud (high fog event) during a Bise situation over the Swiss Plateau in February 2018. In situ microphysical profiles up to 700 m altitude above the ground and at temperatures down to −8 °C and wind speeds up to 15 m s−1 were performed. We were able to capture unique microphysical features from the kilometer down to the meter scale. For example, we observed cloud regions with decreased cloud droplet number concentration (CDNC) and cloud droplet size at scales of 30–50 meters. These cloud inhomogeneities could arise from adiabatic compression and heating and subsequent droplet evaporation in descending air parcels. Moreover, we observed conditions favorable for the formation of boundary layer waves and Kelvin-Helmholtz instability at the cloud top. This potentially influenced the cloud structure on a scale of 10–30 kilometers, which is reflected in the variability of the CDNC.

scholarly journals Damage mechanisms and embrittlement kinetics in a β-rich Ti 17 alloy after long term aging

2020 ◽  
Vol 321 ◽  
pp. 06008
Author(s):  
Layla SASAKI ◽  
Gilbert HENAFF ◽  
Mandana ARZAGHI ◽  
Patrick VILLECHAISE ◽  
Samuel HEMERY ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Detrimental Effect ◽  
Damage Tolerance ◽  
Tensile Tests ◽  
Mechanical Resistance ◽  
Damage Mechanisms ◽  
Structural Parts ◽  
The Impact

The Ti 17 (Ti-5Al-2Sn-2Zr-4Mo-4Cr) alloy is used in the first stages of engine compressors, at temperatures up to 450°C. However, its use in structural parts such as engine pylons is more prospective and raises the question of damage tolerance. As the engine pylon environment involves prolonged exposures to high temperatures, the impact of aging on mechanical properties has also to be taken in account. In this work, the consequences of a long-term aging (up to 10 000 h at 450°C) on the mechanical resistance of a Ti 17 alloy are examined at different scales, from macroscopic fatigue crack growth tests to in-situ tensile tests performed on micro samples in a SEM. The detrimental effect of aging on the mechanical properties of the Ti 17 alloy was then discussed in the light of damage mechanisms analysis and embrittlement kinetics.

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