2,468 research outputs found
Achievement and Integration of Students with Special Needs (SEN) in the Fifth Grade
In Styria 77.3% of all students with special
needs are educated in integrated classrooms.
Currently, it is not known much either about the
school performance nor the active class
participation of these students. This study
examined 230 fifth grade students â 43 with
and 187 students without special educational
needs (SEN). Moreover, it is important to
acknowledge that the available data for this
study represents the first wave of larger
longitudinal study. The school performance of
the students with SEN ranged one standard
deviation below the level of the students
without SEN. All students felt emotionally well
integrated in the school settings, but the
differences in the degree of social integration
were evident. In fact, the students with SEN
mentioned that they got along well with their
classmates less frequently than the students
without SEN
Pi Charge Distribution from Molecular Topology and Pi Orbital Electronegativity
The automatic and computer-aided prediction of reactivity by
means of a few basic atomic parameters is achieved. Considering
that only the topology of a molecule is required for the computation
it is evident that PEOE (partial equalization of orbital electronegativity)
and SD-POE (sigma dependent POE) models proposed by
the authors together establish a valid alternative to the presently
available, time consuming quantum mechanical procedures.
Furthermore, this approach gives a new insight into the interaction
between a and it electrons which seems worthy of further
investigation. In addition, we have revived the concept of orbital
electronegativity, especially in the case of the Jt electrons for which
no calculation based on POE (pi orbital electronegativy) has, up to
now, ever been performed
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Numerical simulations of optical properties of Saharan dust aerosols with emphasis on lidar applications
In the framework of the Saharan Mineral Dust Experiment (SAMUM) for the first time the spectral dependence of particle linear depolarization ratios was measured by combining four lidar systems. In this paper these measurements are compared with results from scattering theory based on the T-matrix method. For this purpose, in situ measurementsâsize distribution, shape distribution and refractive indexâwere used as input parameters; particle shape was approximated by spheroids. A sensitivity study showed that lidar-related parametersâlidar ratio Sp and linear depolarization ratio ÎŽpâare very sensitive to changes of all parameters. The simulated values of the ÎŽp are in the range of 20% and 31% and thus in the range of the measurements. The spectral dependence is weak, so that it could not be resolved by the measurements. Calculated lidar ratios based on the measured microphysics and considering equivalent radii up to 7.5ÎŒm show a range of possible values between 29 and 50 sr at λ = 532 nm. Larger Sp might be possible if the real part of the refractive index is small and the imaginary part is large. A strict validation was however not possible as too many microphysical parameters influence Sp and ÎŽp that could not be measured with the required accuracy
Nickel, Manganese, and Cobalt Dissolution from Ni-Rich NMC and Their Effects on NMC622-Graphite Cell
Characterization of the airborne aerosol inlet and transport system used during the A-LIFE aircraft field experiment
Atmospheric aerosol particles have a profound impact on Earth's climate by scattering and absorbing solar and terrestrial radiation and by impacting the properties of clouds. Research aircraft such as the Deutsches Zentrum fĂŒr Luft- und Raumfahrt e.V. (DLR) Falcon are widely used to study aerosol particles in the troposphere and lower stratosphere. However, transporting a representative sample to the instrumentation inside the aircraft remains a challenge due to high airspeeds and changing ambient conditions. In particular, for high-quality coarse-mode aerosol measurements, knowledge about losses or enhancements in the aerosol sampling system is crucial. In this study, the sampling efficiency of the aerosol inlet aboard the Falcon research aircraft is characterized for the first time with state-of-the art in situ measurements including sizing instruments operated behind the Falcon aerosol inlet and mounted at the aircraft wing not affected by the aerosol inlet. Sampling efficiencies were derived for different true airspeed ranges by comparing the in-cabin and âfullâ-size-range particle number size distributions during 174 flight sequences with a major contribution of mineral dust particles during the âAbsorbing aerosol layers in a changing climate: aging, lifetime and dynamicsâ project (A-LIFE). Additionally, experimentally derived Stokes numbers were used to calculate the cutoff diameter of the aerosol sampling system for different particle densities as a function of true airspeed. As expected, the results show that the velocity of the research aircraft has a major impact on the sampling of coarse-mode aerosol particles with in-cabin instruments. For true airspeeds up to about 190âmâsâ1, aerosol particles larger than about 1â”m are depleted in the sampling system of the Falcon during the A-LIFE project. In contrast, for true airspeeds higher than 190âmâsâ1, an enhancement of particles up to a diameter of 4â”m is observed. For even larger particles, the enhancement effect at the inlet is still present, but inertial and gravitational particle losses in the transport system get more and more pronounced, which leads to a decreasing overall sampling efficiency. In summary, aerosol particles are either depleted or enhanced in the Falcon aerosol inlet, whereas transport in sampling lines always leads to a loss of particles. Here, we have considered both effects and determined the cutoff diameter for the A-LIFE transport system (i.e., the sampling lines only), the cutoff diameter of the Falcon aerosol inlet (i.e., the effect of the inlet only), and the combined effect of the inlet and sampling lines.</p
What is the benefit of ceilometers for aerosol remote sensing? An answer from EARLINET
With the establishment of ceilometer networks by national weather services, a discussion commenced to which extent these simple backscatter lidars can be used for aerosol research. Though primarily designed for the detection of clouds it was shown that at least observations of the vertical structure of the boundary layer might be possible. However, an assessment of the potential of ceilometers for the quantitative retrieval of aerosol properties is still missing. In this paper we discuss different retrieval methods to derive the aerosol backscatter coefficient beta(p),with special focus on the calibration of the ceilometers. Different options based on forward and backward integration methods are compared with respect to their accuracy and applicability. It is shown that advanced lidar systems such as those being operated in the framework of the European Aerosol Research Lidar Network (EARLINET) are excellent tools for the calibration, and thus beta(p) retrievals based on forward integration can readily be implemented and used for real-time applications. Furthermore, we discuss uncertainties introduced by incomplete overlap, the unknown lidar ratio, and water vapor absorption. The latter is relevant for the very large number of ceilometers operating in the spectral range around lambda = 905-910 nm. The accuracy of the retrieved beta(p) mainly depends on the accuracy of the calibration and the long-term stability of the ceilometer. Under favorable conditions, a relative error of beta(p) on the order of 10% seems feasible. In the case of water vapor absorption, corrections assuming a realistic water vapor distribution and laser spectrum are indispensable;otherwise errors on the order of 20% could occur. From case studies it is shown that ceilometers can be used for the reliable detection of elevated aerosol layers below 5 km, and can contribute to the validation of chemistry transport models, e. g.,the height of the boundary layer. However, the exploitation of ceilometer measurements is still in its infancy, so more studies are urgently needed to consolidate the present state of knowledge, which is based on a limited number of case studies
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