873 research outputs found
Notes sobre mortalitat infantil, maternal i incidència de venturers (1567-1800) a Sant Celoni
Challenges for Opioid Receptor Nomenclature
Recent developments in the study of the structure and function of opioid receptors raise significant challenges for the definition of individual receptor types and the development of a nomenclature that precisely describes isoforms that may subserve different functions in vivo. Presentations at the 2013 meeting of the International Narcotics Research Conference in Cairns, Australia, considered some of the new discoveries that are now unravelling the complexities of opioid receptor signalling. Variable processing of opioid receptor messenger RNAs may lead to the presence of several isoforms of the μ receptor. Each opioid receptor type can function either as a monomer or as part of a homo- or heterodimer or higher multimer. Additionally, recent evidence points to the existence of agonist bias in the signal transduction pathways activated through μ receptors, and to the presence of regulatory allosteric sites on the receptors. This brief review summarizes the recent discoveries that raise challenges for receptor definition and the characterization of signal transduction pathways activated by specific receptor forms. LINKED ARTICLES: This article is part of a themed section on Opioids: New Pathways to Functional Selectivity. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2015.172.issue-2.NHMRC 104596
Туризм и внешняя торговля АР Крым: географические аспекты современного развития
Целью данной статьи является оценка современного состояния внешней торговли АР Крым и ее составляющей – туристской деятельности
One loop photon-graviton mixing in an electromagnetic field: Part 2
In part 1 of this series compact integral representations had been obtained
for the one-loop photon-graviton amplitude involving a charged spin 0 or spin
1/2 particle in the loop and an arbitrary constant electromagnetic field. In
this sequel, we study the structure and magnitude of the various polarization
components of this amplitude on-shell. Explicit expressions are obtained for a
number of limiting cases.Comment: 31 pages, 3 figure
Large orders in strong-field QED
We address the issue of large-order expansions in strong-field QED. Our
approach is based on the one-loop effective action encoded in the associated
photon polarisation tensor. We concentrate on the simple case of crossed fields
aiming at possible applications of high-power lasers to measure vacuum
birefringence. A simple next-to-leading order derivative expansion reveals that
the indices of refraction increase with frequency. This signals normal
dispersion in the small-frequency regime where the derivative expansion makes
sense. To gain information beyond that regime we determine the factorial growth
of the derivative expansion coefficients evaluating the first 80 orders by
means of computer algebra. From this we can infer a nonperturbative imaginary
part for the indices of refraction indicating absorption (pair production) as
soon as energy and intensity become (super)critical. These results compare
favourably with an analytic evaluation of the polarisation tensor asymptotics.
Kramers-Kronig relations finally allow for a nonperturbative definition of the
real parts as well and show that absorption goes hand in hand with anomalous
dispersion for sufficiently large frequencies and fields.Comment: 26 pages, 6 figure
Dispersive properties of quasi-phase-matched optical parametric amplifiers
The dispersive properties of non-degenerate optical parametric amplification
in quasi-phase-matched (QPM) nonlinear quadratic crystals with an arbitrary
grating profile are theoretically investigated in the no-pump-depletion limit.
The spectral group delay curve of the amplifier is shown to be univocally
determined by its spectral power gain curve through a Hilbert transform. Such a
constraint has important implications on the propagation of spectrally-narrow
optical pulses through the amplifier. In particular, it is shown that anomalous
transit times, corresponding to superluminal or even negative group velocities,
are possible near local minima of the spectral gain curve. A possible
experimental observation of such effects using a QPM Lithium-Niobate crystal is
suggested.Comment: submitted for publicatio
P.611 Biomarkers of inflammation and neural plasticity in olfactory neuroepithelium-derived cells from patients with major depressive disorder
- …