Search results for "TRACER"
showing 10 items of 145 documents
Acute symptomatic seizures in cerebral venous thrombosis
2020
© 2020 American Academy of Neurology
The accuracy of sentinel lymph node biopsy in the treatment of multicentric invasive breast cancer using a subareolar injection of tracer.
2008
BACKGROUND: The aim of this study was to evaluate the feasibility and the accuracy of sentinel lymph node biopsy in multicentric breast cancer (MBC) performed by means of a subareolar (SA) injection of both 99Tc-labeled human albumin colloid and lymphazurin. METHODS: Between January 2002 and October 2007, 34 patients with MBC with clinically negative axilla underwent sentinel lymph node biopsy (SLNB) followed by total axillary node dissection (AD). Overall successful identification rate of SLN was 100%; there were no false negatives and overall accuracy rate was 100%. RESULTS: The mean number of sentinel lymph nodes (SLNs) identified was 1.8 +/- 0.88 (range = 1-4); the mean number of axilla…
The Influence of Oxidative Stress on Neurological Outcomes in Spontaneous Intracerebral Hemorrhage
2021
Spontaneous intracerebral hemorrhage (ICH) causes, besides the primary brain injury, a secondary brain injury (SBI), which is induced, amongst other things, by oxidative stress (OS) and inflammation, determining the patient’s outcome. This study aims to assess the impact of OS in plasma and cerebrospinal fluid (CSF) on clinical outcomes in patients with ICH. A total of 19 ICH (volume >
Modeling of copper fixed-bed biosorption from wastewater by Posidonia oceanica
2009
Biosorption of copper from aqueous solutions by Posidonia oceanica was investigated in batch and fixed-bed experiments. Batch experiments were conducted to evaluate the removal equilibrium at pH 5.0 and 6.0; experimental data were fitted to Langmuir model with maximum uptake capacities of 56.92 and 85.78 mg g(-1), respectively. Five column experiments were carried out at different feed concentrations. Breakthrough times and continuous sorption isotherm were obtained from breakthrough curves. Differences among batch and continuous isotherms were observed; the maximum uptake capacity in dynamic conditions was found in 56.70 mg g(-1) for final pH between 5.0 and 5.5. The biosorbent was regener…
Dynamics in the extratropical tropopause region: A case of transition between dynamically active and passive tracer advection?
2005
It is argued that certain aspects of tracer patterns and related stirring by the flow in the extratropical tropopause region can be understood in terms of a transition between dynamically active and passive tracer advection, called ‘active-to-passive tracer transition’. In the framework of surface quasi-geostrophic dynamics, a specific initial-value problem is defined and investigated. It features a gradual transition between the two paradigms of tracer advection and allows a clear interpretation thanks to the idealized nature of the model setup. Physical reasoning and anecdotal evidence from previous studies suggest that, at least in specific cases, this interpretation is relevant for the …
Summertime and wintertime atmospheric processes of secondary aerosol in Beijing
2020
Secondary aerosol constitutes a large fraction of fine particles in urban air of China. However, its formation mechanisms and atmospheric processes remain largely uncertain despite considerable study in recent years. To elucidate the seasonal variations in fine-particle composition and secondary aerosol formation, an Aerodyne quadrupole aerosol chemical speciation monitor (Q-ACSM), combined with other online instruments, was used to characterize the sub-micrometer particulate matter (diameter < 1 µm, PM1) in Beijing during summer and winter 2015. Our results suggest that photochemical oxidation was the major pathway for sulfate formation during summer, whereas aqueou…
Transport timescales and tracer properties in the extratropical UTLS
2010
A comprehensive evaluation of seasonal backward trajectories initialized in the northern hemisphere lowermost stratosphere (LMS) has been performed to investigate the factors that determine the temporal and spatial structure of troposphere-to-stratosphere-transport (TST) and it's impact on the LMS. In particular we explain the fundamental role of the transit time since last TST (tTST) for the chemical composition of the LMS. According to our results the structure of the LMS can be characterized by a layer with tTST<40 days forming a narrow band around the local tropopause. This layer extends about 30 K above the local dynamical tropopause, corresponding to the extratropical tropopause trans…
Airborne observation of mixing across the entrainment zone during PARADE 2011
2016
This study presents the analysis of the structure and air mass characteristics of the lower atmosphere during the field campaign PARADE (PArticles and RAdicals: Diel observations of the impact of urban and biogenic Emissions) on Mount Kleiner Feldberg in southwestern Germany during late summer 2011. We analysed measurements of meteorological variables (temperature, moisture, pressure, wind speed and direction) from radio soundings and of chemical tracers (carbon dioxide, ozone) from aircraft measurements. We focus on the thermodynamic and dynamic properties that control the chemical distribution of atmospheric constituents in the boundary layer. We show that the evolution of tracer profiles…
2016
Abstract. Aerosols have important impacts on air quality and climate, but the processes affecting their removal from the atmosphere are not fully understood and are poorly constrained by observations. This makes modelled aerosol lifetimes uncertain. In this study, we make use of an observational constraint on aerosol lifetimes provided by radionuclide measurements and investigate the causes of differences within a set of global models. During the Fukushima Dai-Ichi nuclear power plant accident of March 2011, the radioactive isotopes cesium-137 (137Cs) and xenon-133 (133Xe) were released in large quantities. Cesium attached to particles in the ambient air, approximately according to their av…
An evaluation of the estimation of road traffic emission factors from tracer studies
2010
Road traffic emission factors (EFs) are one of the main sources of uncertainties in emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently. Recently an alternative method has been proposed to estimate the EFs. In that work the emission factors were estimated from a long term tracer study developed in Ho Chi Minh City (HCMC) Vietnam. A passive tracer was continuously emitted from a finite line source placed in one side of an urban street canyon. Simultaneously, the resulting tracer concentrations were monitored at the other side of the street. The results of this experiment were used to calculate the dispersion factors an…