2,025 research outputs found
Topological phase in two flavor neutrino oscillations
We show that the phase appearing in neutrino flavor oscillation formulae has
a geometric and topological contribution. We identify a topological phase
appearing in the two flavor neutrino oscillation formula using Pancharatnam's
prescription of quantum collapses between non-orthogonal states. Such quantum
collapses appear naturally in the expression for appearance and survival
probabilities of neutrinos. Our analysis applies to neutrinos propagating in
vacuum or through matter. For the minimal case of two flavors with CP
conservation, our study shows for the first time that there is a geometric
interpretation of the neutrino oscillation formulae for the detection
probability of neutrino species.Comment: 11 pages, 3 figures, accepted in Phys. Rev.
Lepton Polarization in Neutrino-Nucleon Interactions
We derive generic formulas for the polarization density matrix of leptons
produced in neutrino and antineutrino collisions and briefly consider some
important particular cases. Next we employ the general formalism in order to
include the final lepton mass and spin into the popular model by Rein and
Sehgal for single pion neutrinoproduction.Comment: Talk given at 10th International Workshop on High-Energy Spin Physics
(SPIN 03), Dubna, Russia, 16-20 Sep 2003. 12 pages; extended version, typos
remove
Calcium-permeable channels activated via guanine nucleotide-dependent mechanism in human carcinoma cells
AbstractPatch clamp experiments on human carcinoma A431 cells have revealed two types of Ca2+-permeable channels, the activity of which can be increased by the application of non-hydrolyzable analogues of GTP to the intracellular side of the membrane. With 105 mM Ca2+ in recording pipette at 30–33°C their unitary conductances (in pS) are 1.3 (SG-channels) and 2.4 (G-channels). G- and, possibly, SG-channels are activated from the extracellular side of the membrane with epidermal growth factor (EGF). The data are consistent with the hypothesis that both channels are activated via guanine nucleotide binding (G) proteins
Effects of experimental rewilding on butterflies, bumblebees and grasshoppers
© The Author(s) 2022. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made.Grassland ecosystems are species-rich habitats that are rapidly declining globally posing serious concerns for biodiversity conservation. This situation is particularly relevant in agricultural areas in Europe. As traditional management practices and livestock grazing regimes ceased, rewilding could be a potential avenue to tackle current biodiversity declines. To test this hypothesis, we set up a 3-year experiment where 12 horses were introduced in three 10-hectare enclosure replicates (four horses per enclosure). Horses were kept without supplementary feeding to mimic ecosystem functions of wild horses. We applied Generalized Linear Mixed Effects Models and a backward stepwise model selection procedure to elucidate factors that modulate insect richness induced by grazing. Our results show that plant species richness, the proportion of flowers and plant height play a significant role for butterfly and bumblebee richness, while the opposite effect was detected for grasshoppers. However, the effect on grasshoppers was counterbalanced by increased grasshopper species richness in habitats adjacent to horse latrines. Rewilding with horses may offset current biodiversity declines by maintaining important functional links between plants and pollinators in grassland ecosystems. Horse grazing can however have different effects on diverse functional groups of insects. Application of integrative landscape scale approaches may be needed to elucidate the effects of rewilding for certain functional groups such as grasshoppers. With current biodiversity declines, up-scaling rewilding research and practice might be crucial to mitigate the pervasive effects on insects as their services and functions are critical for our existence.publishedVersio
The role of apical support and rectal mucosal prolapse excision in successful treatment of rectocele combined with perineum descending: short-term and follow-up results
The aim of the research was to improve the results of surgery treatment of posterior compartment of pelvic floor using abdominal sacrocolpopexy and stapled trance-anal resection (STARR
The advantages of the abdominal sacral colpopexy combined with stapled trance-anal resection of the rectal mucosal prolapse (STARR) for the surgical treament of perineum descending syndrome
The problem of pelvic organ prolapse in women is still actual, because of high frequency of this pathology. Several surgical techniques have been suggested for pelvic descending syndrome treatment. But a large number of complications, unsatisfactory anatomical and functional results of suggested methods force to look for other solutions of the proble
Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments
Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects
(HiRes, AUGER, TA, EUSO, TUS,...) use air fluorescence to detect and measure
extensive air showers (EAS). The precise knowledge of the Fluorescence Light
Yield (FLY) is of paramount importance for the reconstruction of UHECR. The
MACFLY - Measurement of Air Cherenkov and Fluorescence Light Yield - experiment
has been designed to perform such FLY measurements. In this paper we will
present the results of FLY in the 290-440 nm wavelength range for dry air and
pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50
GeV. The experiment uses a 90Sr radioactive source for low energy measurement
and a CERN SPS electron beam for high energy. We find that the FLY is
proportional to the deposited energy (E_d) in the gas and we show that the air
fluorescence properties remain constant independently of the electron energy.
At the reference point: atmospheric dry air at 1013 hPa and 23C, the ratio
FLY/E_d=17.6 photon/MeV with a systematic error of 13.2%.Comment: 19 pages, 8 figures. Accepted for publication in Astroparticle
Physic
- …