Modelonderzoek meetpunt Slenaken : "Flat - 5 triangular profile weir"

In de buurt van de Belgische grens werd in de Gulp te Slenaken (Zd. Limburg) door Rijkswaterstaat een meetstuw gebouwd van het type "Flat-V triangular profile weir". Een schaalmodel van de meetstuw is in Wageningen geijkt. De afvoergegevens zullen ook worden gebruikt door de "Studiegroep Gulp"

Bright source of spectrally uncorrelated polarization-entangled photons with nearly single-mode emission

We present results of a bright polarization-entangled photon source operating at 1552 nm via type-II collinear degenerate spontaneous parametric down-conversion in a periodically poled potassium titanyl phosphate crystal. We report a conservative inferred pair generation rate of 123,000 pairs/s/mW into collection modes. Minimization of spectral and spatial entanglement was achieved by group velocity matching the pump, signal and idler modes and through properly focusing the pump beam. By utilizing a pair of calcite beam displacers, we are able to overlap photons from adjacent down-conversion processes to obtain polarization-entanglement visibility of 94.7 +/- 1.1% with accidentals subtracted.Comment: 4 pages, 7 color figures. Revised manuscript includes the following changes: corrected pair generation rate from 44,000/s/mW pump to 123,000/s/mW pump; replaced Fig. 1b to enhance clarity; minor alterations to the title, abstract and introduction; grammatical correction

Viscosity Is Not a Parameter of Postdeglutitive Pharyngeal Residue: Quantification and Analysis with Scintigraphy

The aim of this study was to explore the influence of viscosity on pharyngeal residue in normal healthy volunteers. Scintigraphy was used to measure pharyngeal residue in 11 healthy volunteers after swallowing three different substances (age = 20.2–48.3 years). The first substance was a 10-ml solution of tap water with 0.5% xanthan with a viscosity of 4500 mPa s, comparable to a yogurt drink. The second and third substances were a 0.75% xanthan and a 1.00% xanthan solution, with viscosities of 10,500 and 21,000 mPa s, comparable to low-fat yogurt and 3% fat yogurt, respectively. Tap water was used as the control substance. Mean pharyngeal residue after swallowing tap water was 2.3% (SD = 1.2) of the initial volume in the oral cavity. Pharyngeal residue after swallowing 0.5% xanthan solution was 1.8% (SD = 0.8), after swallowing 0.75% xanthan solution 2.6% (SD = 2.2), and after swallowing 1.00% xanthan solution 2.8% (SD = 1.7). No significant correlation between increase of viscosity and pharyngeal residue was found. In healthy persons viscosity does not seem to be a significant parameter for pharyngeal residue for boluses with viscosities ranging from tap water to solutions having a viscosity comparable to 3% fat yogurt

Generation of degenerate, factorizable, pulsed squeezed light at telecom wavelengths

We characterize a periodically poled KTP crystal that produces an entangled, two-mode, squeezed state with orthogonal polarizations, nearly identical, factorizable frequency modes, and few photons in unwanted frequency modes. We focus the pump beam to create a nearly circular joint spectral probability distribution between the two modes. After disentangling the two modes, we observe Hong-Ou-Mandel interference with a raw (background corrected) visibility of 86 % (95 %) when an 8.6 nm bandwidth spectral filter is applied. We measure second order photon correlations of the entangled and disentangled squeezed states with both superconducting nanowire single-photon detectors and photon-number-resolving transition-edge sensors. Both methods agree and verify that the detected modes contain the desired photon number distributions

A Bayesian analysis of classical shadows

The method of classical shadows heralds unprecedented opportunities for quantum estimation with limited measurements [H.-Y. Huang, R. Kueng, and J. Preskill, Nat. Phys. 16, 1050 (2020)]. Yet its relationship to established quantum tomographic approaches, particularly those based on likelihood models, remains unclear. In this article, we investigate classical shadows through the lens of Bayesian mean estimation (BME). In direct tests on numerical data, BME is found to attain significantly lower error on average, but classical shadows prove remarkably more accurate in specific situations -- such as high-fidelity ground truth states -- which are improbable in a fully uniform Hilbert space. We then introduce an observable-oriented pseudo-likelihood that successfully emulates the dimension-independence and state-specific optimality of classical shadows, but within a Bayesian framework that ensures only physical states. Our research reveals how classical shadows effect important departures from conventional thinking in quantum state estimation, as well as the utility of Bayesian methods for uncovering and formalizing statistical assumptions.Comment: 8 pages, 5 figure

A Clinical Perspective on the Criteria for Liver Resection and the Use of Liver Function Tests

Ó The Author(s) 2009. This article is published with open access at Springerlink.com To the Editor, In a recently published survey of 100 liver centers, Breitenstein et al. [1] reported that on a global scale, (1) the average minimal remnant liver volume for resection is 25% (range = 15-40%) for normal liver parenchyma and 50% (range = 25–90%) for cirrhotic livers, (2) portal vein occlusion is employed in 89 % of the centers for purposes of augmenting liver volume before surgery, and that (3) 38 % of the centers employed liver function tests as part of their clinical routine, of which 76 % used the ICG clearance test. The interesting survey provoked a few issues that we feel obliged to address. The authors contend that ‘‘below a certain volume, a remnant liver cannot sustain metabolic, synthetic, and detoxifying functions’ ’ [1]—a statement that is unequivocal and uncontested. However, it should be born in mind that liver volume is not a directly proportional measure of liver function. We have demonstrated a few fundamental aspects of the volume-function relationship that support this notion: (i) Whereas liver function correlates with volume in uncompromised livers [2], there is significantly less correlation between liver volume an