Towards quantum-chemical method development for arbitrary basis functions

We present the design of a flexible quantum-chemical method development framework, which supports employing any type of basis function. This design has been implemented in the light-weight program package molsturm, yielding a basis-function-independent self-consistent field scheme. Versatile interfaces, making use of open standards like python, mediate the integration of molsturm with existing third-party packages. In this way both rapid extension of the present set of methods for electronic structure calculations as well as adding new basis function types can be readily achieved. This makes molsturm well-suitable for testing novel approaches for discretising the electronic wave function and allows comparing them to existing methods using the same software stack. This is illustrated by two examples, an implementation of coupled-cluster doubles as well as a gradient-free geometry optimisation, where in both cases, an arbitrary basis functions could be used. molsturm is open-source and can be obtained from https://molsturm.org.Comment: 15 pages and 7 figure

A wavelength-tunable fiber-coupled source of narrowband entangled photons

We demonstrate a wavelength-tunable, fiber-coupled source of polarization-entangled photons with extremely high spectral brightness and quality of entanglement. Using a 25 mm PPKTP crystal inside a polarization Sagnac interferometer we detect a spectral brightness of 273000 pairs/(s mW nm), a factor of 28 better than comparable previous sources while state tomography showed the two-photon state to have a tangle of T=0.987. This improvement was achieved by use of a long crystal, careful selection of focusing parameters and single-mode fiber coupling. We demonstrate that, due to the particular geometry of the setup, the signal and idler wavelengths can be tuned over a wide range without loss of entanglement.Comment: 10 pages, 5 figures. Article rewritten, added Fig.(1a-1b). Published in Optics Express, comments welcom

Measuring mutual fund herding - A structural approach

This paper proposes a methodological improvement to empirical studies of herd behavior based on investor transactions. By developing a simple model of trading behavior, we show that the traditionally used herding measure produces biased results. As this bias depends on characteristics of the data, it also affects the robustness of previous findings. We derive a new measure that is unbiased and shows superior statistical properties for data sets commonly used. In an analysis of the German mutual fund market, our measure provides new insights into fund manager herding that would have been undetected under the traditional statistic

A method for determining the central lateral position of a spray swath

Die Genauigkeit zweier Systeme, die bei der Applikation mit Luftfahrzeugen durch Versatz der Flugbahnen den Einfluss des Seitenwindes auf die Verteilung der Spritzflüssigkeit kompensieren sollen, wurde experimentell ermit­telt. Dabei wurden sehr unterschiedliche Verteilungsmuster festgestellt, so dass eine geeignete Berechnung der Position des Behandlungsstreifens gefunden werden musste. Zur Beschreibung der Position des Behandlungsstreifens wurde, in Anlehnung an die Berechnung des Schwerpunktes in der Mechanik, der Belagsschwerpunkt ermittelt. Die Berechnung wird im Beitrag beschrieben.An aerial swath offset experiment was conducted to measure the accuracy of two commercial navigational systems for compensation of cross wind influence. The swaths produced in this experiment presented many different deposit patterns. A method was required to determine a position for the differing distributions on the ground. This paper describes a possible solution of this problem. Equivalent to the centre of gravity in mechanics, the use of a Centre of Deposition calculation proved appropriate. The way of calculation is exemplified

Measuring Mutual Fund Herding - A Structural Approach

This paper proposes a methodological improvement to empirical studies of herd behavior based on investor transactions. By developing a simple model of trading behavior, we show that the traditionally used herding measure produces biased results. As this bias depends on characteristics of the data, it also affects the robustness of previous findings. We derive a new measure that is unbiased and shows superior statistical properties for data sets commonly used. In an analysis of the German mutual fund market, our measure provides new insights into fund manager herding that would have been undetected under the traditional statistic

Research on application techniques and on test methods at the Institute of Application Techniques in Plant Protection

Neben der Prüfung von Pflanzenschutzgeräten ist Forschung in unterschiedlichen Bereichen der Applikationstechnik und Pflanzenschutzverfahren eine vorrangige Aufgabe des Instituts für Anwendungstechnik im Pflanzenschutz. Die vielfältigen Projekte lassen sich in zwei Hauptrichtungen unterscheiden: Die prüfungsbegleitende Forschung und die anwendungstechnische Forschung. Der Beitrag gibt für beide Hauptrichtungen einen Überblick über laufende oder kürzlich abgeschlossene Pro­jekte; jeweils ein Projekt wird ausführlicher erläutert. DOI: 10.5073/JfK.2014.10.04, https://doi.org/10.5073/JfK.2014.10.04In addition to the testing of plant protection equipment, research in different areas of application techniques and plant protection methods is a main task of the Institute for Application Techniques in Plant Protection. The diverse projects can be classified as research assigned to the testing as well as research assigned to application techniques. This paper will give a review of ongoing and recently completed projects for both classes; detailed explanations are given for one project of each class. DOI: 10.5073/JfK.2014.10.04, https://doi.org/10.5073/JfK.2014.10.0

Electronic systems for sprayers

In den letzten Jahren wurden verschiedene elektronische Systeme entwickelt, um die Anwendung chemischer Pflanzenschutzmittel zu verbessern. Ein Überblick wird gegeben, einzelne Systeme werden im Detail erläutert und Testergebnisse vorgestellt, die deren Leistungsfähigkeit charakterisieren. Elektronische Systeme tragen dazu bei, angestrebte Applikationsparameter, wie beispielsweise die Dosierung der Pflanzenschutzmittel, besser einzuhalten und unbeabsichtigte Auswirkungen auf die Umwelt zu reduzieren. Gleichzeitig helfen Spritzcomputer und automatische Regelungen, die Produktivität zu erhöhen und den Anwender zu entlasten.In recent years, an increasing number of electronic systems has been developed in order to improve the performance of chemical application techniques. An overview is given, particular systems are explained in detail and test results characterizing their performance are presented. Electronic systems help to achieve intended application parameters, such as chemical dose rate, more accurately and to reduce unintended environmental impact. At the same time, spray computers and automatic controls help to increase productivity and to relief operators

Quantum chemistry with Coulomb Sturmians:Construction and convergence of Coulomb Sturmian basis sets at the Hartree-Fock level

The first discussion of basis sets consisting of exponentially decaying Coulomb Sturmian functions for modelling electronic structures is presented. The proposed basis set construction selects Coulomb Sturmian functions using separate upper limits to their principle, angular momentum and magnetic quantum numbers. Their common Coulomb Sturmian exponent is taken as a fourth parameter. The convergence properties of such basis sets are investigated for second and third row atoms at the Hartree-Fock level. Thereby important relations between the values of the basis set parameters and the physical properties of the electronic structure are recognised. For example, an unusually large limit for the angular momentum quantum number in unrestricted Hartree-Fock calculations can be linked to the breaking of spherical symmetry in such cases. Furthermore, a connection between the optimal, i.e. minimum-energy, Coulomb Sturmian exponent and the average Slater exponents values obtained by Clementi and Raimondi (E. Clementi and D. L. Raimondi, J. Chem. Phys. 38, 2686 (1963)) is made. These features of Coulomb Sturmian basis sets emphasise their ability to correctly reproduce the physical features of Hartree-Fock wave functions.Comment: 16 pages, 14 figures, supporting inf

Customer preferences with regard to milk packaging

The milk industry in the Eastern Cape is very competitive and milk suppliers must use all means, including packaging, to influence buying behaviour. The aim of the study was to investigate customer preferences with regard to milk packaging in the Nelson Mandela Bay (NMB) area. The purpose was to develop a better understanding of customer preferences so that packaging could be designed to satisfy customer expectations and needs. The research design was based on a quantitative approach (non-experimental) and the study was descriptive in nature. The measuring instrument was a self-developed questionnaire, which was developed based on the literature study and previous empirical studies conducted by Adam and Ali (2014a) and Ahmed, Pumar and Amin (2014). The sample consisted of 199 adult shoppers in the Nelson Mandela Bay area, selected through snowball and quota sampling. Data was collected with the help of fieldworkers, coded into Microsoft Excel and processed with statistical software. Descriptive statistics and canonical correlation analysis were used to identify customer preferences and relationships between the different dimensions of milk packaging. The results revealed that size, materials, convenience in handing and product information (expiry date) were important. Colour and design were not regarded as important by the target group