4,100 research outputs found
Photodissociation of NO2 in the (2)B-2(2) state: A slice imaging study and reinterpretation of previous results
The photodissociation dynamics of nitrogen dioxide have been probed above the second dissociation limit at photolysis wavelengths close to 226 nm. The O(3PJ)+NO(2) product channel has been examined using direct current slice velocity map imaging of the O(3PJ) and NO(2) fragments. Mass-resolved resonantly enhanced multiphoton ionization spectroscopy and velocity map imaging have been used to probe directly the rovibrational population distributions of the NO fragments. We also examine possible interference from the dissociation of N2O4 by investigating the effect of the sample temperature on the O(3PJ) fragment energy distributions. The O(3PJ)+NO(2) dissociation channel has been found to favor the production of vibrationally cold, highly rotationally excited NO(2) products with all three oxygen spin-orbit components. Other minor dissociation channels which produce O(3PJ) atoms have also been identified. We discuss the significance of these dissociation channels and present a reinterpretation of previous studies of NO2 dissociation on excitation to the (2)2B2 state
Seafood from Norway : food safety
Since Norway is a major supplier of seafood
worldwide, monitoring the food safety of Norwegian fish
products is a priority. This commentary gives a brief
overview of the food safety of seafood from Norwegian
waters. Several preventative measures during harvest/catch,
processing and distribution have been established and
are implemented regularly. Furthermore, comprehensive
monitoring programmes to detect and quantify undesirable
substances, such as heavy metals and polychlorinated
biphenyls (PCBs), in Norwegian seafood are carried out.
Substances with health benefits, such as omega-3 fatty
acids, are also analysed. In general, evidence shows the
level of undesirable substances in seafood from Norway to
be low. In fact, in the majority of samples analysed, levels
of undesirable substances were reported to be below the
maximum limit set by the European Union (EU). This leads
to the conclusion that consumption of seafood originating
from Norway involves a low risk of negative health effects
and that consumers can have confidence in the products
they purchase.peer-reviewe
Exploring Gifted Pedagogy: Evaluating Teacher Knowledge and Implementation of Common Core Professional Learning
The purpose of this quantitative study was to determine the effectiveness of professional learning with teachers on the Core Six Essential Strategies (CSES) within a gifted multicultural context. Criterion sampling was employed to identify the participants for the study. All participants were teachers of gifted and talented students within a large southeastern urban district. All participants met the gifted endorsement state credentialing criteria. A pre-experimental, single-group pretest-posttest design was constructed. Instruments employed in the study were the Association of Supervision and Curriculum Developmentâs Core Six Pre-Post Assessment (ASCD, 2012) and a modified participant reaction questionnaire. Four research questions were explored in the study. Guskey and Sparkâs Model of Relationship between Professional Development and Improvements in Student Learning was the research paradigm employed to analyze the results of the study.
A dependent samples t-test was used to find if there was a significant difference between the pre and posttest means of teacher knowledge on the Core Six Essential Strategies. To explore implementation, a dependent samples t-test was used to find if there was a significant difference between the index of intended frequency of use and the actual use of strategies. Descriptive statistics including the count and mean were examined to show which aspects of the professional learning have most value. Descriptive statistics indicating the count, mean, and variance were used to examine to what extent the professional learning prepared teachers to instruct within a multicultural gifted urban context.
Findings indicated a significant difference in knowledge of the CSES; the participants intended to implement the strategies significantly more than they did; and several aspects of the professional learning were valuable and prepared them to teach in a multicultural gifted urban context. In summary, the research was significant to the field of gifted education because the results will inform future professional learning decisions, curriculum writing, and program implementation designed to improve student learning outcomes
Spatial solitons under competing linear and nonlinear diffractions
We introduce a general model which augments the one-dimensional nonlinear
Schr\"{o}dinger (NLS) equation by nonlinear-diffraction terms competing with
the linear diffraction. The new terms contain two irreducible parameters and
admit a Hamiltonian representation in a form natural for optical media. The
equation serves as a model for spatial solitons near the supercollimation point
in nonlinear photonic crystals. In the framework of this model, a detailed
analysis of the fundamental solitary waves is reported, including the
variational approximation (VA), exact analytical results, and systematic
numerical computations. The Vakhitov-Kolokolov (VK) criterion is used to
precisely predict the stability border for the solitons, which is found in an
exact analytical form, along with the largest total power (norm) that the waves
may possess. Past a critical point, collapse effects are observed, caused by
suitable perturbations. Interactions between two identical parallel solitary
beams are explored by dint of direct numerical simulations. It is found that
in-phase solitons merge into robust or collapsing pulsons, depending on the
strength of the nonlinear diffraction
The Arizona Summit: Tough Times in a Tough Land
Western repositories have much to gain and little to lose from statewide initiatives that promote cooperative collection management policies. The region\u27s topography, demographics, boom-bust cycles, and flood of new residents threaten their missions and their very existence. Add competition, backlogs, duplication, and fragmented collections to this volatile mix and it renders the collecting environment untenable
Time-dependent photoionization of azulene: Competition between ionization and relaxation in highly excited states
Pump-probe photoionization has been used to map the relaxation processes taking place from highly vibrationally excited levels of the S2 state of azulene, populated directly or via internal conversion from the S4 state. Photoelectron spectra obtained by 1+2â two-color time-resolved photoelectron imaging are invariant (apart from in intensity) to the pump-probe time delay and to pump wavelength. This reveals a photoionization process which is driven by an unstable electronic state (e.g. doubly excited state) lying below the ionization potential. This state is postulated to be populated by a probe transition from S2 and to rapidly relax via an Auger like process onto highly
vibrationally excited Rydberg states. This accounts for the time invariance of the photoelectron spectrum. The intensity of the photoelectron spectrum is proportional to the population in S2. An exponential energy gap law is used to describe the internal conversion rate from S2 to S0. The
vibronic coupling strength is found to be larger than 60±5 ΌeV
A Bayesian approach for determining player abilities in football
We consider the task of determining a football playerâs ability for a given event type, for example, scoring a goal. We propose an interpretable Bayesian model which is fit using variational inference methods. We implement a Poisson model to capture occurrences of event types, from which we infer player abilities. Our approach also allows the visualisation of differences between players, for a specific ability, through the marginal posterior variational densities. We then use these inferred player abilities to extend the Bayesian hierarchical model of Baio and Blangiardo (2010, Journal of Applied Statistics, 37(2), 253â264) which captures a teamâs scoring rate (the rate at which they score goals). We apply the resulting scheme to the English Premier League, capturing player abilities over the 2013/2014 season, before using output from the hierarchical model to predict whether over or under 2.5 goals will be scored in a given game in the 2014/2015 season. This validates our model as a way of providing insights into team formation and the individual success of sports teams
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