632 research outputs found
Platform price parity clauses and market segmentation
Price parity clauses (PPCs) are widely adopted by online platforms to force client sellers not to lower their prices elsewhere. We investigate under what conditions online travel agencies (OTAs) decide to apply PPCs, and how this affects hotels' listing decisions on OTAs. We find OTAs adopt PPCs when there is a sufficiently large competitive pressure in the market, either between OTAs, or between hotels (or both). PPCs allow OTAs to charge higher commission fees to hotels, which can respond by delisting from certain OTAs, thereby segmenting the market. We also find that consumers and hotels generally lose out with PPCs
Superintegrability and higher order polynomial algebras II
In an earlier article, we presented a method to obtain integrals of motion
and polynomial algebras for a class of two-dimensional superintegrable systems
from creation and annihilation operators. We discuss the general case and
present its polynomial algebra. We will show how this polynomial algebra can be
directly realized as a deformed oscillator algebra. This particular algebraic
structure allows to find the unitary representations and the corresponding
energy spectrum. We apply this construction to a family of caged anisotropic
oscillators. The method can be used to generate new superintegrable systems
with higher order integrals. We obtain new superintegrable systems involving
the fourth Painleve transcendent and present their integrals of motion and
polynomial algebras.Comment: 11 page
Structure of a bacterial type IV secretion core complex at subnanometre resolution
Type IV secretion (T4S) systems are able to transport DNAs and/or proteins through the membranes of bacteria. They form large multiprotein complexes consisting of 12 proteins termed VirB1-11 and VirD4. VirB7, 9 and 10 assemble into a 1.07 MegaDalton membrane-spanning core complex (CC), around which all other components assemble. This complex is made of two parts, the O-layer inserted in the outer membrane and the I-layer inserted in the inner membrane. While the structure of the O-layer has been solved by X-ray crystallography, there is no detailed structural information on the I-layer. Using high-resolution cryo-electron microscopy and molecular modelling combined with biochemical approaches, we determined the I-layer structure and located its various components in the electron density. Our results provide new structural insights on the CC, from which the essential features of T4S system mechanisms can be derived
Tropical Grass Growth Functions Modeling by Using Nonlinear Mixed Models
Nonlinear Growth curves are used for modeling plant physiological variables. These models are preferable because the polynomial coefficients of the equations have a biological significance. The response variables of the curves occurs commonly with repeated measurements over time and measurements are on different environments. The traditional statistical analysis does not include a repeated measures approach, which can lead to improper estimation of the error terms. It is important to study the growth of tropical grass (Da Silva and Carvalho 2005)
WEANING INDEXES DO NOT PREDICT SUCCESS WITH NON INVASIVE MECHANICAL VENTILATION IN EXTUBATION FAILURE
Laserâfacilitated epicutaneous immunotherapy with depigmented house dust mite extract alleviates allergic responses in a mouse model of allergic lung inflammation
Background
Skin-based immunotherapy of type 1 allergies has recently been re-investigated as an alternative for subcutaneous injections. In the current study, we employed a mouse model of house dust mite (HDM)-induced lung inflammation to explore the potential of laser-facilitated epicutaneous allergen-specific treatment.
Methods
Mice were sensitized against native Dermatophagoides pteronyssinus extract and repeatedly treated by application of depigmented D pteronyssinus extract via laser-generated skin micropores or by subcutaneous injection with or without alum. Following aerosol challenges, lung function was determined by whole-body plethysmography and bronchoalveolar lavage fluid was analyzed for cellular composition and cytokine levels. HDM-specific IgG subclass antibodies were determined by ELISA. Serum as well as cell-bound IgE was measured by ELISA, rat basophil leukemia cell assay, and ex vivo using a basophil activation test, respectively. Cultured lymphocytes were analyzed for cytokine secretion profiles and cellular polarization by flow cytometry.
Results
Immunization of mice by subcutaneous injection or epicutaneous laser microporation induced comparable IgG antibody levels, but the latter preferentially induced regulatory T cells and in general downregulated T cell cytokine production. This effect was found to be a result of the laser treatment itself, independent from extract application. Epicutaneous treatment of sensitized animals led to induction of blocking IgG, and improvement of lung function, superior compared to the effects of subcutaneous therapy. During the whole therapy schedule, no local or systemic side effects occurred.
Conclusion
Allergen-specific immunotherapy with depigmented HDM extract via laser-generated skin micropores offers a safe and effective treatment option for HDM-induced allergy and lung inflammation
An infinite family of superintegrable systems from higher order ladder operators and supersymmetry
We will discuss how we can obtain new quantum superintegrable Hamiltonians
allowing the separation of variables in Cartesian coordinates with higher order
integrals of motion from ladder operators. We will discuss also how higher
order supersymmetric quantum mechanics can be used to obtain systems with
higher order ladder operators and their polynomial Heisenberg algebra. We will
present a new family of superintegrable systems involving the fifth Painleve
transcendent which possess fourth order ladder operators constructed from
second order supersymmetric quantum mechanics. We present the polynomial
algebra of this family of superintegrable systems.Comment: 8 pages, presented at ICGTMP 28, accepted for j.conf.serie
Superintegrable systems with spin and second-order integrals of motion
We investigate a quantum nonrelativistic system describing the interaction of
two particles with spin 1/2 and spin 0, respectively. We assume that the
Hamiltonian is rotationally invariant and parity conserving and identify all
such systems which allow additional integrals of motion that are second order
matrix polynomials in the momenta. These integrals are assumed to be scalars,
pseudoscalars, vectors or axial vectors. Among the superintegrable systems
obtained, we mention a generalization of the Coulomb potential with scalar
potential and spin orbital one
.Comment: 32 page
Group Approach to the Quantization of the P\"oschl-Teller dynamics
The quantum dynamics of a particle in the Modified P\"oschl-Teller potential
is derived from the group by applying a Group Approach to
Quantization (GAQ). The explicit form of the Hamiltonian as well as the ladder
operators is found in the enveloping algebra of this basic symmetry group. The
present algorithm provides a physical realization of the non-unitary,
finite-dimensional, irreducible representations of the group. The
non-unitarity manifests itself in that only half of the states are
normalizable, in contrast with the representations of SU(2) where all the
states are physical.Comment: 17 pages, LaTe
System Dynamics of Cognitive Vulnerabilities and Family Support Among Latina Children and Adolescents
The paper describes an approach to developing a data-driven development of a feedback theory of cognitive vulnerabilities and family support focused on understanding the dynamics experienced among Latina children, adolescents, and families. Family support is understood to be a response to avoidant and maladaptive behaviors that may be characteristic of cognitive vulnerabilities commonly associated depression and suicidal ideation. A formal feedback theory is developed, appraised, and analyzed using a combination of secondary analysis of qualitative interviews (Nâ=â30) and quantitative analysis using system dynamics modeling and simulation. Implications for prevention practice, treatment, and future research are discussed
- âŠ