7,942 research outputs found
Method to measure off-axis displacements based on the analysis of the intensity distribution of a vortex beam
We study the properties of the Fraunhofer diffraction patterns produced by
Gaussian beams crossing spiral phase plates. We show, both analytically and
numerically, that off-axis displacements of the input beam produce asymmetric
diffraction patterns. The intensity profile along the direction of maximum
asymmetry shows two different peaks. We find that the intensity ratio between
these two peaks decreases exponentially with the off-axis displacement of the
incident beam, the decay being steeper for higher strengths of the optical
singularity of the spiral phase plate. We analyze how this intensity ratio can
be used to measure small misalignments of the input beam with a very high
precision.Comment: 8 pages, 4 figures. Accepted for publication in PR
Constraints on Cosmological Parameters from the 500 degÂČ SPTPOL Lensing Power Spectrum
We present cosmological constraints based on the cosmic microwave background (CMB) lensing potential power spectrum measurement from the recent 500 degÂČ SPTPOL survey, the most precise CMB lensing measurement from the ground to date. We fit a flat ÎCDM model to the reconstructed lensing power spectrum alone and in addition with other data sets: baryon acoustic oscillations (BAO), as well as primary CMB spectra from Planck and SPTPOL. The cosmological constraints based on SPTPOL and Planck lensing band powers are in good agreement when analyzed alone and in combination with Planck full-sky primary CMB data. With weak priors on the baryon density and other parameters, the SPTPOL CMB lensing data alone provide a 4% constraint on ÏâΩ^(0.25)_m = 0.593 ± 0.025. Jointly fitting with BAO data, we find Ïâ = 0.779±0.023, Ω_m = 0.368^(+0.032)_(â0.037), and Hâ = 72.0^(+2.1)_(â2.5)kmsâ»Âč Mpcâ»Âč, up to 2Ï away from the central values preferred by Planck lensing + BAO. However, we recover good agreement between SPTPOL and Planck when restricting the analysis to similar scales. We also consider single-parameter extensions to the flat ÎCDM model. The SPTPOL lensing spectrum constrains the spatial curvature to be Ω_K = â0.0007±0.0025 and the sum of the neutrino masses to be âm_Îœ < 0.23 eV at 95% C.L. (with Planck primary CMB and BAO data), in good agreement with the Planck lensing results. With the differences in the signal-to-noise ratio of the lensing modes and the angular scales covered in the lensing spectra, this analysis represents an important independent check on the full-sky Planck lensing measurement
SBV Regularity for Genuinely Nonlinear, Strictly Hyperbolic Systems of Conservation Laws in one space dimension
We prove that if is the entropy
solution to a strictly hyperbolic system of conservation laws with
genuinely nonlinear characteristic fields then up to a
countable set of times the function is in
, i.e. its distributional derivative is a measure with no
Cantorian part.
The proof is based on the decomposition of into waves belonging to
the characteristic families and the balance
of the continuous/jump part of the measures in regions bounded by
characteristics. To this aim, a new interaction measure \mu_{i,\jump} is
introduced, controlling the creation of atoms in the measure .
The main argument of the proof is that for all where the Cantorian part
of is not 0, either the Glimm functional has a downward jump, or there is
a cancellation of waves or the measure is positive
Physiological Responses to Acute Silver Exposure in the Freshwater Crayfish (\u3cem\u3eCambarus diogenes diogenes\u3c/em\u3e)âA Model Invertebrate?
Adult crayfish (Cambarus diogenes diogenes) exposed to 8.41 ± 0.17 Όg silver/L (19.4% as Ag+) in moderately hard freshwater under flow-through conditions for 96 h exhibited ionoregulatory disturbance, elevated metabolic ammonia (Tamm) production and substantial silver accumulation in the gills, hemolymph, and hepatopancreas. The ionoregulatory disturbance included both a generally reduced unidirectional Na1 influx and an increased unidirectional Na+ efflux, leading to a substantial net loss of Na+ from the silver-exposed crayfish. The Na+ uptake in silver-exposed crayfish differed overall from controls, while the increased Na+ efflux recovered to control values 48 h into the 96 h of exposure. The general inhibition of Na+ uptake could be explained by a reduced sodium/potassium-adenosine triphosphatase (Na/K-ATPase) activity in terminally obtained gill samples from the silver exposed crayfish. The silver-induced effect on Na+ uptake and loss translated to reduced hemolymph Na+ concentrations but not significantly reduced hemolymph Cl- concentrations. Hemolymph Tamm and Tamm efflux both increased in silver-exposed crayfish, indicating an increased metabolic Tamm production. The present study demonstrates that the toxic mechanism of waterborne silver exposure in freshwater crayfish resembles that of freshwater teleost fish. The crayfish might therefore be a useful model system for extending current environmental regulatory strategies, currently based on teleost fish, to invertebrates
Standardization of molecular monitoring for chronic myeloid leukemia in Latin America using locally produced secondary cellular calibrators
Residual disease in chronic myeloid leukemia (CML) patients undergoing therapy with tyrosine kinase inhibitors (TKIs) is measured by assessing the quantity of transcripts of the BCR-ABL1 fusion gene in peripheral white blood cells. This analysis is based on reverse-transcription quantitative PCR (RTâqPCR) technology; however, the wide array of methods used worldwide has led to large variation in quantitative BCR-ABL1 measurements, which hamper inter-laboratory comparative studiesFil: Ruiz, MarĂa Sol. FundaciĂłn CĂĄncer. Centro de Investigaciones OncolĂłgicas; ArgentinaFil: Medina, M.. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Tapia, I.. FundaciĂłn CĂĄncer. Centro de Investigaciones OncolĂłgicas; ArgentinaFil: Mordoh, Jose. FundaciĂłn CĂĄncer. Centro de Investigaciones OncolĂłgicas; ArgentinaFil: Cross, N. C. P.. Universidad de Southampton Uk; Reino UnidoFil: Larripa, Irene Beatriz. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Instituto de Medicina Experimental. Academia Nacional de Medicina de Buenos Aires. Instituto de Medicina Experimental; ArgentinaFil: Bianchini, Michele. FundaciĂłn CĂĄncer. Centro de Investigaciones OncolĂłgicas; Argentin
Auto-oscillation threshold, narrow spectral lines, and line jitter in spin-torque oscillators based on MgO magnetic tunnel junctions
We demonstrate spin torque induced auto-oscillation in MgO-based magnetic
tunnel junctions. At the generation threshold, we observe a strong line
narrowing down to 6 MHz at 300K and a dramatic increase in oscillator power,
yielding spectrally pure oscillations free of flicker noise. Setting the
synthetic antiferromagnet into autooscillation requires the same current
polarity as the one needed to switch the free layer magnetization. The induced
auto-oscillations are observed even at zero applied field, which is believed to
be the acoustic mode of the synthetic antiferromagnet. While the phase
coherence of the auto-oscillation is of the order of microseconds, the power
autocorrelation time is of the order of milliseconds and can be strongly
influenced by the free layer dynamics
Operando High-Pressure NMR and IR Study of the Hydroformylation of 1-Hexene by 1,1’-Bis-(Diarylphosphino)metallocene-Modified Rhodium(I) Catalyst
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