2,852 research outputs found
Selfdecomposability of Weak Variance Generalised Gamma Convolutions
Weak variance generalised gamma convolution processes are multivariate
Brownian motions weakly subordinated by multivariate Thorin subordinators.
Within this class, we extend a result from strong to weak subordination that a
driftless Brownian motion gives rise to a self-decomposable process. Under
moment conditions on the underlying Thorin measure, we show that this condition
is also necessary. We apply our results to some prominent processes such as the
weak variance alpha-gamma process, and illustrate the necessity of our moment
conditions in some cases
Intrinsically Legal-For-Trade Objects by Digital Signatures
The established techniques for legal-for-trade registration of weight values
meet the legal requirements, but in praxis they show serious disadvantages. We
report on the first implementation of intrinsically legal-for-trade objects,
namely weight values signed by the scale, that is accepted by the approval
authority. The strict requirements from both the approval- and the
verification-authority as well as the limitations due to the hardware of the
scale were a special challenge. The presented solution fulfills all legal
requirements and eliminates the existing practical disadvantages.Comment: 4 pages, 0 figure
Spin of ground state baryons
We calculate the quark spin contribution to the total angular momentum of
flavor octet and flavor decuplet ground state baryons using a spin-flavor
symmetry based parametrization method of quantum chromodynamics. We find that
third order SU(6) symmetry breaking three-quark operators are necessary to
explain the experimental result Sigma_1=0.32(10). For spin 3/2 decuplet baryons
we predict that the quark spin contribution is Sigma_3=3.93(22), i.e.
considerably larger than their total angular momentum.Comment: 8 page
Effect of Photobiomodulation on Vinblastine-Poisoned Murine HERS Cells
Objective: The aim of this study was to investigate the effect of near-infrared (NIR) photobiomodulation on the proliferation and glutathione levels in murine Hertwig\u27s epithelial root sheath (HERS) cells after poisoning with vinblastine. Background: Photobiomodulation has been shown to improve wound healing in a number of animal models. There have been no studies on the effect of photobiomodulation on cancer-related chemotherapy injury to the cells that initiate tooth root growth. Materials and Methods: Control groups consisted of murine HERS cells without vinblastine (VB−) and cells with vinblastine at 10, 20, and 30 ng/mL (VB10, VB20, and VB30). Experimental groups consisted of these same groups with light therapy (VB-L, VB10L, VB20L, and VB30L). The cells were exposed to vinblastine for 1 h. Photobiomodulation consisted of a 75-cm2 gallium-aluminum-arsenide light-emitting diode (LED) array at an energy density of 12.8 J/cm2, delivered with 50 mW/cm2 power over 256 s. Results: Vinblastine alone significantly decreased HERS cell proliferation and glutathione levels at all concentrations (VB10 [−55%, p \u3c 1.0 × 10−8]; VB20 [−72%, p \u3c 1.0 × 10−9]; VB30 [−80%, p \u3c 1.0 × 10−10]; and VB10 [−36%, p \u3c 0.0001]; VB20 [−49%, p \u3c 1.0 × 10−6]; VB30 [−53%, p \u3c 1.0 × 10−7] respectively). Photobiomodulation significantly increased cell proliferation at all levels of vinblastine exposure (VB10L [+50%, p \u3c 0.0001]; VB20L [+45%, p \u3c 0.05]; VB30 [+39%, p \u3c 0.05]) but not of the control (+22%, p  = 0.063). The photobiomodulation significantly increased glutathione production in all concentrations of vinblastine except 20 ng/mL (VB10L [+39%, p = 0.007]; VB20L [+19%, p = 0.087]; VB30 [+14%, p = 0.025]) and the control (+12%, p = 0.13). Conclusions: Photobiomodulation demonstrated an improvement in proliferation and glutathione levels in vinblastine-poisoned murine HERS cells
Extended van Royen-Weisskopf formalism for lepton-antilepton meson decay widths within non-relativistic quark models
The classical van Royen-Weisskopf formula for the decay width of a meson into
a lepton-antilepton pair is modified in order to include non-zero quark
momentum contributions within the meson as well as relativistic effects.
Besides, a phenomenological electromagnetic density for quarks is introduced.
The meson wave functions are obtained from two different models: a chiral
constituent quark model and a quark potential model including instanton
effects. The modified van Royen-Weisskopf formula is found to improve
systematically the results for the widths, giving an overall good description
of all known decays.Comment: 22 pages, 3 figures, RevTex, epsfig. To be published in Nucl. Phys.
System and performance audit of surface ozone, carbon monoxide, methane, carbon dioxide and nitrous oxide at the Global GAW Station Izaña, Spain
The 7th system and performance audit by WCC-Empa at the global GAW station Izaña, which is run by the State Meteorological Agency of Spain (AEMET), was conducted from 15 to 21 May 2019 in agreement with the WMO/GAW quality assurance system (WMO, 2017).Activities of WCC-Empa and QA/SAC Switzerland are financially supported by MeteoSwiss and Empa
Baryon Charge Radii and Quadrupole Moments in the 1/N_c Expansion: The 3-Flavor Case
We develop a straightforward method to compute charge radii and quadrupole
moments for baryons both with and without strangeness, when the number of QCD
color charges is N_c. The minimal assumption of the single-photon exchange
ansatz implies that only two operators are required to describe these baryon
observables. Our results are presented so that SU(3) flavor and isospin
symmetry breaking can be introduced according to any desired specification,
although we also present results obtained from two patterns suggested by the
quark model with gluon exchange interactions. The method also permits to
extract a number of model-independent relations; a sample is r^2_Lambda / r_n^2
= 3/(N_c+3), independent of SU(3) symmetry breaking.Comment: 30 pages, no figures, REVTeX
Generation of mechanical squeezing via magnetic dipoles on cantilevers
A scheme to squeeze the center-of-mass motional quadratures of a quantum
mechanical oscillator below its standard quantum limit is proposed and analyzed
theoretically. It relies on the dipole-dipole coupling between a magnetic
dipole mounted on the tip of a cantilever to equally oriented dipoles located
on a mesoscopic tuning fork. We also investigate the influence of several
sources of noise on the achievable squeezing, including classical noise in the
driving fork and the clamping noise in the oscillator. A detection of the state
of the cantilever based on state transfer to a light field is considered. We
investigate possible limitations of that scheme.Comment: 11 pages, 11 figures, submitted to PR
Comparison of continuous in situ CO2 observations at Jungfraujoch using two different measurement techniques
Since 2004, atmospheric carbon dioxide (CO2) is being measured at the High Altitude Research Station Jungfraujoch by the division of Climate and Environmental Physics at the University of Bern (KUP) using a nondispersive infrared gas analyzer (NDIR) in combination with a paramagnetic O2 analyzer. In January 2010, CO2 measurements based on cavity ring-down spectroscopy (CRDS) as part of the Swiss National Air Pollution Monitoring Network were added by the Swiss Federal Laboratories for Materials Science and Technology (Empa). To ensure a smooth transition – a prerequisite when merging two data sets, e.g., for trend determinations – the two measurement systems run in parallel for several years. Such a long-term intercomparison also allows the identification of potential offsets between the two data sets and the collection of information about the compatibility of the two systems on different time scales. A good agreement of the seasonality, short-term variations and, to a lesser extent mainly due to the short common period, trend calculations is observed. However, the comparison reveals some issues related to the stability of the calibration gases of the KUP system and their assigned CO2 mole fraction. It is possible to adapt an improved calibration strategy based on standard gas determinations, which leads to better agreement between the two data sets. By excluding periods with technical problems and bad calibration gas cylinders, the average hourly difference (CRDS – NDIR) of the two systems is −0.03 ppm ± 0.25 ppm. Although the difference of the two data sets is in line with the compatibility goal of ±0.1 ppm of the World Meteorological Organization (WMO), the standard deviation is still too high. A significant part of this uncertainty originates from the necessity to switch the KUP system frequently (every 12 min) for 6 min from ambient air to a working gas in order to correct short-term variations of the O2 measurement system. Allowing additional time for signal stabilization after switching the sample, an effective data coverage of only one-sixth for the KUP system is achieved while the Empa system has a nearly complete data coverage. Additionally, different internal volumes and flow rates may affect observed differences
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