Direct Measurement of Kirkwood-Rihaczek distribution for spatial properties of coherent light beam

We present direct measurement of Kirkwood-Rihaczek (KR) distribution for spatial properties of coherent light beam in terms of position and momentum (angle) coordinates. We employ a two-local oscillator (LO) balanced heterodyne detection (BHD) to simultaneously extract distribution of transverse position and momentum of a light beam. The two-LO BHD could measure KR distribution for any complex wave field (including quantum mechanical wave function) without applying tomography methods (inverse Radon transformation). Transformation of KR distribution to Wigner, Glauber Sudarshan P- and Husimi or Q- distributions in spatial coordinates are illustrated through experimental data. The direct measurement of KR distribution could provide local information of wave field, which is suitable for studying particle properties of a quantum system. While Wigner function is suitable for studying wave properties such as interference, and hence provides nonlocal information of the wave field. The method developed here can be used for exploring spatial quantum state for quantum mapping and computing, optical phase space imaging for biomedical applications.Comment: 27 pages, 14 figure

Gesprekskwaliteit bij De Kindertelefoon

In 2020 is De Kindertelefoon gestart met het project ‘inzicht in kwaliteitsprocessen’, met als doel om inzicht te krijgen in de kwaliteit van het kindcontact bij De Kindertelefoon. Daarnaast wil De Kindertelefoon meer inzicht in hoe dit verbeterd kan worden en hoe de kwaliteit met regelmaat gemeten kan worden. Dit proj ect vormde de aanleiding om in het najaar van 2021 het Kohnstamm Instituut opdracht geven voor een nulmeting van de gesprekskwaliteit bij De Kindertelefoon, aan de hand van de recent vastgestelde kwaliteitscriteria 1 . In het kader van deze nulmeting, voerden we in samenwerking met De Kindertelefoon drie gerelateerde deelonderzoeken uit. In elk deelonderzoek werd een andere groep bevraagd over de kwaliteit van de gesprekken: (1) Kinderen rapporteerden hun tevredenheid o ver het gevoerde gesprek; (2) Werkbegeleiders beoordeelden de kwaliteit van gesprekken tussen kinderen en vrijwilligers; (3) Vrijwilligers beoordeelden de (zelf ingeschatte) kwaliteit van hun eigen gesprekken. In dit onderzoeksrapport doen we verslag van deze drie nulmetingen. De resultaten geven inzicht in de kwaliteit van het kindcontact bij De Kindertelefoon vanuit verschillende gezichtspunten. Ook geeft het onderzoek inzicht in welke factoren voorspellend zi gesprekskwaliteit, en op welke punten de kwaliteit verbeterd zou kunnen worden

How to Educate Entrepreneurs?

Entrepreneurship education has two purposes: To improve students’ entrepreneurial skills and to provide impetus to those suited to entrepreneurship while discouraging the rest. While entrepreneurship education helps students to make a vocational decision its effects may conflict for those not suited to entrepreneurship. This study shows that vocational and the skill formation effects of entrepreneurship education can be identified empirically by drawing on the Theory of Planned Behavior. This is embedded in a structural equation model which we estimate and test using a robust 2SLS estimator. We find that the attitudinal factors posited by the Theory of Planned Behavior are positively correlated with students’ entrepreneurial intentions. While conflicting effects of vocational and skill directed course content are observed in some individuals, overall these types of content are complements. This finding contradicts previous results in the literature. We reconcile the conflicting findings and discuss implications for the design of entrepreneurship courses

Quantitative Analysis of Bloggers Collective Behavior Powered by Emotions

Large-scale data resulting from users online interactions provide the ultimate source of information to study emergent social phenomena on the Web. From individual actions of users to observable collective behaviors, different mechanisms involving emotions expressed in the posted text play a role. Here we combine approaches of statistical physics with machine-learning methods of text analysis to study emergence of the emotional behavior among Web users. Mapping the high-resolution data from digg.com onto bipartite network of users and their comments onto posted stories, we identify user communities centered around certain popular posts and determine emotional contents of the related comments by the emotion-classifier developed for this type of texts. Applied over different time periods, this framework reveals strong correlations between the excess of negative emotions and the evolution of communities. We observe avalanches of emotional comments exhibiting significant self-organized critical behavior and temporal correlations. To explore robustness of these critical states, we design a network automaton model on realistic network connections and several control parameters, which can be inferred from the dataset. Dissemination of emotions by a small fraction of very active users appears to critically tune the collective states