1,356 research outputs found
The aerodynamical laboratory of the Vienna Technical High School
We will give here only a short explanation of the operation of the plant and deal principally with the question of what it has accomplished
Nonadiabatic transitions in electrostatically trapped ammonia molecules
Nonadiabatic transitions are known to be major loss channels for atoms in
magnetic traps, but have thus far not been experimentally reported upon for
trapped molecules. We have observed and quantified losses due to nonadiabatic
transitions for three isotopologues of ammonia in electrostatic traps, by
comparing the trapping times in traps with a zero and a non-zero electric field
at the center. Nonadiabatic transitions are seen to dominate the overall loss
rate even for samples at relatively high temperatures of 10-50 mK
Applications of Density Functional Theory to Theoretical Organic Chemistry
An overview of applications of density functional theory (KS/DZVP-GGA,
demon2k, or B3LYP/6-311G(d,p), Gaussian 09) to a wide range of problems in
theoretical organic chemistry with examples is given, namely thermodynamic
properties, geometries (bullvalene), charges (glycine cation), dipole moments,
electrostatic potential (acetyl chloride and acetamide), spectroscopy
(IR/Raman: acetaldehyde, UV/Vis: polyenes, NMR: thujone and EPR: Koelsch’s
radical), gas phase acidities and pKa values (substituted benzoic acids),
supramolecular chemistry (quinhydrone complex), and reaction pathways
Amnesie-Filme : eine Auswahlfilmographie
Amnesie-Filme: Eine Auswahlfilmographie. Zusammengestellt von Katja Kirste
Mineral Saturation State and the Implications for Reaction Rates in Reactive Transport Modeling of CO2 Storage
AbstractThe injection of CO2 results in a decrease in the pH and a corresponding change from conditions at or near saturation between the aqueous and mineral phases to one of undersaturation. With growing evidence that many mineral dissolution reaction rates are dependent on the proximity to equilibrium, we seek to address the extent to which a fluid becomes undersaturated with respect to the mineral phases present through the addition of CO2. It turns out, for many minerals with a dissolution reaction that is pH dependent, that the saturation index changes little from the initially saturated condition. This indicates that reaction rates commonly used in reaction path and reactive transport models of carbon storage are not sufficiently representative of the dissolution mechanism that dominates and tend to overestimate the amount of reaction with time
Atopic Disease Prevention — A Research Schema for Evaluating Skin Barrier Protection and Phthalate Exposure Reduction
Rationale
Globally, the prevalence of atopic diseases continues to rise. Up to 20% of the population is thought to be affected, exerting enormous health, social and financial burdens. Emerging data suggests atopic dermatitis precedes allergic sensitization and may increase the predisposition to food allergy, allergic rhinitis and asthma later in life. Pilot testing has suggested infant skin barrier protection may reduce the risk of atopic dermatitis. Parallel research has suggested exposure to phthalates may be driving the inflammatory process at the dermal level.
Methods
The altered skin barrier and hapten-atopy hypotheses are summarized. A schema for a pragmatically designed, randomized controlled trial is developed to address: 1.Does skin barrier protection using an occlusive moisturizer and measures to reduce phthalate exposure among infants reduce the incidence of atopic dermatitis and the prevalence of atopic diseases, and 2.If so, do these interventions reduce risk in an additive or synergistic manner?
Results
Population based recruitment of newborn infants to one of three interventions or a control arm is proposed. The first arm would involve the application of an occlusive skin moisturizer to protect skin barrier integrity; the second, measures to reduce dietary and environmental phthalate exposures and the third would add skin barrier protection to the phthalate exposure reduction protocol. The protocol phase would ideally continue for three years, while the observation phase for the detection of disease incidence and prevalence would span 18 years. Recommendations for data interpretation include regression analysis for modeling the intervention effects on other environmental and dietary exposures thought to increase the risk of atopic diseases.
Conclusions
Pragmatic design would optimize the generalizability of the results. Study findings would clarify public health approaches for atopic disease prevention by broadening the current understanding of the effects of phthalates on child health and by informing best practices for infant skin care
The body language of dairy calves
While improving animal welfare has become an important task in both the
agricultural and scientific community, increased knowledge on positive emotions
in animals and on methods of assessing welfare are needed in order to continue
to move forward in this endeavour. Through understanding the connection
between the body language of animals and their emotional state, further progress
can be made. This study assessed the ear postures, tail postures, and stepping
behaviour of 16 dairy calves when exposed to four experimental stimuli expected
to elicit emotional states of varying valence and arousal levels, and a control.
The stimuli included feeding of concentrates, gentle stroking, the absence of
social interactions/stimuli, and spraying with water. Results were then compared
to body posture predictions based on previous research where ear and tail
postures of dairy cows during different activities were analyzed and plotted onto
an arousal/valence framework i.e. the dimensional model of core affect.
Predictions for the ear postures backward, asymmetric right, and asymmetric
left during a positive, low arousal emotional state showed a trend of being
supported. The backward and forward ear postures of calves may be more
influenced by changes in arousal, while the asymmetric right ear indicated an
emotional state of positive, high arousal. The highest occurrence of stepping
behaviour was displayed during the boredom stimulus, indicating that this
treatment was perceived as being of high arousal by the calves, rather than low
arousal as intended. Overall tail activity of the calves was low. No tail predictions
were confirmed, however, a new posture of a tucked tail seemed to be
representative of a negative, high arousal emotional state. Further research is
needed to determine the role that age, experience, and stimuli play in regards to
an animal’s emotional state and to determine the validity of using the
dimensional model of core affect to predict the body language and emotional
state of animals in varying situations
Spectroscopy, Substituent Effects, and Reaction Mechanisms
Applications of density functional theory (DFT) calculations to organic chemistry are shown, beginning with geometry optimization and the calculation of vibrational frequencies, infrared (IR) intensities, and thermodynamic properties. The isotropic chemical shielding values and anisotropies relevant to nuclear magnetic resonance (NMR) can be calculated using gauge-invariant atomic orbitals (GIAOs); the calculation of spin-spin couplings is possible but time-consuming. For free radicals, hyperfine couplings and g tensors pertaining to EPR can be obtained. Regarding UV/vis spectra, wavelengths and oscillator strengths can be calculated by using a time-dependent Hamiltonian. In addition to gas-phase acidities, approximate pKa values can be obtained, provided that solvation is taken into account. Several sets of substituent parameters have been calculated: Hammett σ and σ+ parameters and inductive and mesomeric effects. Regarding reaction mechanisms, geometries and energies of intermediates and transition structures have been calculated for pericyclic reactions, nucleophilic aliphatic substitutions, electrophilic aromatic substitutions, additions, and eliminations
The effect of early environment on the adaptability of chicks
Due to the many challenges that laying hens face throughout their lives in the
production system, raising hens with the ability to adapt and cope within their
environment is vital from both a welfare and production standpoint. The early
environment of chicks has been shown to have lasting effects on the health and well
being of laying hens later in life. However, few studies have investigated the effects
of early environment and adaptability. This study investigated cognitive functions
and learning capabilities, which are pivotal in developing adaptation skills, of 48
laying hens at the age of 9-14 weeks using a holeboard test. Hens were raised in
differing environments over two periods of rearing: early rearing from 0-4 weeks of
age and current rearing from 5-15 weeks of age. The treatments consisted of choice
of substrate and perch (four types of each) vs. no choice of substrate or perch (i.e.
one type of each), which was changed between the two rearing periods for half of the
birds, resulting in four different treatments i.e. choice/choice (CC), choice/no-choice
(CN), no-choice/no-choice (NN), and no-choice/choice (NC). When habituating
individually to the holeboard test, birds from treatment CC found more worms than
those from treatments NN and CN (p=0.004; p=0.03). During acquisition, a
significantly higher number of birds from CC and NC completed the start trials
when compared to NN and CN birds (p=0.04). Furthermore, results from the
reversal phase indicated that NC birds had a higher reference memory than NN
birds. Overall these results suggest that having choice in the current rearing
environment influenced the birds’ success in the holeboard test, which may in turn
be directly related the their ability to adapt to new environments and circumstances.
Supplementary studies into the critical stage of early rearing and when choice is
best suited to be introduced may provide further insights into the role that choice
plays on the adaptability of laying hens
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