Any characterization of a single-photon source is not complete without specifying its second-order degree of coherence, i.e., its \(g^{(2)}\) function. An accurate measurement of such coherence ...functions commonly requires high-precision single-photon detectors, in whose absence, only time-averaged measurements are possible. It is not clear, however, how the resulting time-averaged quantities can be used to properly characterize the source. In this paper, we investigate this issue for a heralded source of single photons that relies on continuous-wave parametric down-conversion. By accounting for major shortcomings of the source and the detectors--i.e., the multiple-photon emissions of the source, the time resolution of photodetectors, and our chosen width of coincidence window--our theory enables us to infer the true source properties from imperfect measurements. Our theoretical results are corroborated by an experimental demonstration using a PPKTP crystal pumped by a blue laser, that results in a single-photon generation rate about 1.2 millions per second per milliwatt of pump power. This work takes an important step toward the standardization of such heralded single-photon sources.
Multi-order interference and Born's rule Sollner, I. N.; Gschosser, B.; Mai, P. ...
2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC)
Conference Proceeding
We will present the latest limit on multiorder interference as well as detector nonlinearity calibration measurements and an estimation of the ultimate limit one may achieve with this method using a ...range of sources and detectors.
This study sets out to test Born's rule to verify the fundamental postulates of quantum mechanics. This study looks for any deviation from the quantum mechanical triadditivity of three mutually ...exclusive events. Experimentally, a "three-path interference" that can not be explained through the Born interpretation of probabilities is investigated. An upper bound on any such possible deviation from Born's rule is determined.
Various methods for characterizing binding forces as well as for monitoring and remote control of ion channels are still emerging. A recent innovation is the direct incorporation of unnatural amino ...acids (UAAs) with corresponding biophysical or biochemical properties, which are integrated using genetic code expansion technology. Minimal changes to natural amino acids, which are achieved by chemical synthesis of corresponding UAAs, are valuable tools to provide insight into the contributions of physicochemical properties of side chains in binding events. To gain unique control over the conformational changes or function of ion channels, a series of light-sensitive, chemically reactive and posttranslationally modified UAAs have been developed and utilized. Here, we present the existing UAA tools, their mode of action, their potential and limitations as well as their previous applications to Ca
-permeable ion channels.
The reform of the Buildings Energy Act is intended to increase the share of renewable energies in the heat sector. But the proposed measures (among which the promotion of electric heat pumps figures ...prominently) are ecologically ineffective. They will not decrease the total amount of CO
emissions in Germany, which are already subject to the caps of national and European emissions trading systems. Installing heat pumps in the building stock will require high investments and thus make any emission reductions in the heat sector much more expensive than in other sectors. Furthermore, due to its command-and-control approach, the bill is incompatible with the central principles of the German Social Market Economy.
Abstract The Carbon Border Adjustment Mechanism proposed by the European Commission will only be able to prevent part of carbon leakage. It will cause high costs and fail to create incentives for ...non-EU countries to lower their carbon emissions. The mechanism is not compatible with WTO principles and will cause trade conflicts from which Germany, due to its high export surpluses, will suffer most. Therefore, the proposal of the Commission should not be realised. Instead, to compensate for the competitive disadvantages of EU industry, the tried and proven system of allocating free ETS certificates should be continued.
There is much evidence that metacognitive judgments, such as people’s predictions of their future memory performance (judgments of learning, JOLs), are inferences based on cues and heuristics. ...However, relatively little is known about whether and when people integrate multiple cues in one metacognitive judgment or focus on a single cue without integrating further information. The current set of experiments systematically addressed whether and to what degree people integrate multiple extrinsic and intrinsic cues in JOLs. Experiment
1
varied two cues: number of study presentations (1 vs. 2) and font size (18 point vs. 48 point). Results revealed that people integrated both cues in their JOLs. Experiment
2
demonstrated that the two word characteristics concreteness (abstract vs. concrete) and emotionality (neutral vs. emotional) were integrated in JOLs. Experiment
3
showed that people integrated all four cues in their JOLs when manipulated simultaneously. Finally, Experiment
4
confirmed integration of three cues that varied on a continuum rather than in two easily distinguishable levels. These results demonstrate that people have a remarkable capacity to integrate multiple cues in metacognitive judgments. In addition, our findings render an explanation of cue effects on JOLs in terms of demand characteristics implausible.
Due to its close resemblance, the domesticated pig has proven to be a diverse animal model for biomedical research and genome editing tools have contributed to developing porcine models for several ...human diseases. By employing the CRISPR-Cas9 system, porcine embryos or somatic cells can be genetically modified to generate the desired genotype. However, somatic cell nuclear transfer (SCNT) of modified somatic cells and embryo manipulation are challenging, especially if the desired genotype is detrimental to the embryo. Direct in vivo edits may facilitate the production of genetically engineered pigs by integrating Cas9 into the porcine genome. Cas9 expressing cells were generated by either random integration or transposon-based integration of Cas9 and used as donor cells in SCNT. In total, 15 animals were generated that carried a transposon-based Cas9 integration and two pigs a randomly integrated Cas9. Cas9 expression was confirmed in muscle, tonsil, spleen, kidney, lymph nodes, oral mucosa, and liver in two boars. Overall, Cas9 expression was higher for transposon-based integration, except in tonsils and liver. To verify Cas9 activity, fibroblasts were subjected to in vitro genome editing. Isolated fibroblasts were transfected with guide RNAs (gRNA) targeting different genes (GGTA1, B4GALNT2, B2M) relevant to xenotransplantation. Next generation sequencing revealed that the editing efficiencies varied (2-60%) between the different target genes. These results show that the integrated Cas9 remained functional, and that Cas9 expressing pigs may be used to induce desired genomic modifications to model human diseases or further evaluate in vivo gene therapy approaches.
The pig is an important model organism for biomedical research, mainly due to its extensive genetic, physiological and anatomical similarities with humans. Until date, direct conversion of somatic ...cells into hepatocyte-like cells (iHeps) has only been achieved in rodents and human cells. Here, we employed lentiviral vectors to screen a panel of 12 hepatic transcription factors (TF) for their potential to convert porcine fibroblasts into hepatocyte-like cells. We demonstrate for the first time, hepatic conversion of porcine somatic cells by over-expression of CEBPα, FOXA1 and HNF4α2 (3TF-piHeps). Reprogrammed 3TF-piHeps display a hepatocyte-like morphology and show functional characteristics of hepatic cells, including albumin secretion, Dil-AcLDL uptake, storage of lipids and glycogen and activity of cytochrome P450 enzymes CYP1A2 and CYP2C33 (CYP2C9 in humans). Moreover, we show that markers of mature hepatocytes are highly expressed in 3TF-piHeps, while fibroblastic markers are reduced. We envision piHeps as useful cell sources for future studies on drug metabolism and toxicity as well as in vitro models for investigation of pig-to-human infectious diseases.
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