1,138 research outputs found
All orders structure and efficient computation of linearly reducible elliptic Feynman integrals
We define linearly reducible elliptic Feynman integrals, and we show that
they can be algorithmically solved up to arbitrary order of the dimensional
regulator in terms of a 1-dimensional integral over a polylogarithmic
integrand, which we call the inner polylogarithmic part (IPP). The solution is
obtained by direct integration of the Feynman parametric representation. When
the IPP depends on one elliptic curve (and no other algebraic functions), this
class of Feynman integrals can be algorithmically solved in terms of elliptic
multiple polylogarithms (eMPLs) by using integration by parts identities. We
then elaborate on the differential equations method. Specifically, we show that
the IPP can be mapped to a generalized integral topology satisfying a set of
differential equations in -form. In the examples we consider the
canonical differential equations can be directly solved in terms of eMPLs up to
arbitrary order of the dimensional regulator. The remaining 1-dimensional
integral may be performed to express such integrals completely in terms of
eMPLs. We apply these methods to solve two- and three-points integrals in terms
of eMPLs. We analytically continue these integrals to the physical region by
using their 1-dimensional integral representation.Comment: The differential equations method is applied to linearly reducible
elliptic Feynman integrals, the solutions are in terms of elliptic
polylogarithms, JHEP version, 50 page
The Zeldovich & Adhesion approximations, and applications to the local universe
The Zeldovich approximation (ZA) predicts the formation of a web of
singularities. While these singularities may only exist in the most formal
interpretation of the ZA, they provide a powerful tool for the analysis of
initial conditions. We present a novel method to find the skeleton of the
resulting cosmic web based on singularities in the primordial deformation
tensor and its higher order derivatives. We show that the A_3-lines predict the
formation of filaments in a two-dimensional model. We continue with
applications of the adhesion model to visualise structures in the local (z <
0.03) universe.Comment: 9 pages, 8 figures, Proceedings of IAU Symposium 308 "The Zeldovich
Universe: Genesis and Growth of the Cosmic Web", 23-28 June 2014, Tallinn,
Estoni
Adoption of IS Development Methods Across Cultural Boundaries
In IS practice as well as in the literature, IS development methods are prominently espoused. IS development methods are used around the world and globalization of business stimulates their harmonization. To our knowledge, no empirical research has been reported regarding the effect of national cultures on the actual (non-)adoption of IS development methods, which is the focus of this research project. The study is based on Hofstedes well-known research (conducted within IBM), which has provided a conceptual foundation for cross-national research over the past two decades. Data encompassing approximately 40 countries were collected within one global consulting firm. The outcomes of this study are expected to have implications for how global organizations can introduce new development methods more effectively
Spin-orbit torques and photocurrents in 2D materials
While conventional electronics rely on the electron charge as information carrier, using another intrinsic property of the electron, its spin, offers promising ways to further improve information storage technologies. However, the key hurdle lies in gaining precise control over the electron spin. Currently, both electrical and optical methods are being explored to achieve this control.This thesis delves into the realm of spintronics and optoelectronics, focusing on the effects observed in layered two-dimensional (2D) materials called transition metal dichalcogenides (TMDs). These materials are particularly well-suited for this purpose due to their direct bandgap in atomically thin layers and strong spin-orbit coupling, which is advantageous for spintronic and optospintronic effects.The initial section of the thesis addresses spintronic effects, specifically the spin-orbit torque (SOT) in TMD/ferromagnetic bilayers. Notably, our study on WSe2/permalloy devices reveals a lack of clear dependence on WSe2 thickness for SOTs, suggesting an interfacial origin. Additionally, we observe the presence of SOTs in a device with a single ferromagnetic layer, highlighting the importance of studying reference samples for accurate determination of the SOT strength.Turning to the optoelectronic aspect of TMDs, our exploration uncovers that the Schottky barrier at the MoSe2-metallic contacts interface induces additional polarization-dependent photocurrents. Furthermore, we demonstrate that modifying the crystal structure of MoTe2 locally enhances the optoelectronic performance of TMDs based devices.This thesis provides important steps for the integration of 2D materials in future spintronic and optoelectronic devices
Spin-orbit torques and photocurrents in 2D materials
While conventional electronics rely on the electron charge as information carrier, using another intrinsic property of the electron, its spin, offers promising ways to further improve information storage technologies. However, the key hurdle lies in gaining precise control over the electron spin. Currently, both electrical and optical methods are being explored to achieve this control.This thesis delves into the realm of spintronics and optoelectronics, focusing on the effects observed in layered two-dimensional (2D) materials called transition metal dichalcogenides (TMDs). These materials are particularly well-suited for this purpose due to their direct bandgap in atomically thin layers and strong spin-orbit coupling, which is advantageous for spintronic and optospintronic effects.The initial section of the thesis addresses spintronic effects, specifically the spin-orbit torque (SOT) in TMD/ferromagnetic bilayers. Notably, our study on WSe2/permalloy devices reveals a lack of clear dependence on WSe2 thickness for SOTs, suggesting an interfacial origin. Additionally, we observe the presence of SOTs in a device with a single ferromagnetic layer, highlighting the importance of studying reference samples for accurate determination of the SOT strength.Turning to the optoelectronic aspect of TMDs, our exploration uncovers that the Schottky barrier at the MoSe2-metallic contacts interface induces additional polarization-dependent photocurrents. Furthermore, we demonstrate that modifying the crystal structure of MoTe2 locally enhances the optoelectronic performance of TMDs based devices.This thesis provides important steps for the integration of 2D materials in future spintronic and optoelectronic devices
In an Article Written by Henry Hidding Dated 12 March 1912 About the Ninth Street Church or the Pillar Church and Published in the Holland City News on the 14th of March
In an article written by Henry Hidding dated 12 March 1912 about the Ninth Street Church or the Pillar Church and published in the Holland City News on the 14th of March, the author related the meeting in the church during the Civil War in which Dr. Albertus C. Van Raalte participated in the recruitment of soldiers for Company 1 of the 25th Michigan Infantry. Van Raalte had opened the meeting which was lengthy and gave an address. Hidding had been at this lengthy meeting and related his memories of the event.https://digitalcommons.hope.edu/vrp_1910s/1002/thumbnail.jp
The Zeldovich approximation: key to understanding Cosmic Web complexity
We describe how the dynamics of cosmic structure formation defines the
intricate geometric structure of the spine of the cosmic web. The Zeldovich
approximation is used to model the backbone of the cosmic web in terms of its
singularity structure. The description by Arnold et al. (1982) in terms of
catastrophe theory forms the basis of our analysis.
This two-dimensional analysis involves a profound assessment of the
Lagrangian and Eulerian projections of the gravitationally evolving
four-dimensional phase-space manifold. It involves the identification of the
complete family of singularity classes, and the corresponding caustics that we
see emerging as structure in Eulerian space evolves. In particular, as it is
instrumental in outlining the spatial network of the cosmic web, we investigate
the nature of spatial connections between these singularities.
The major finding of our study is that all singularities are located on a set
of lines in Lagrangian space. All dynamical processes related to the caustics
are concentrated near these lines. We demonstrate and discuss extensively how
all 2D singularities are to be found on these lines. When mapping this spatial
pattern of lines to Eulerian space, we find a growing connectedness between
initially disjoint lines, resulting in a percolating network. In other words,
the lines form the blueprint for the global geometric evolution of the cosmic
web.Comment: 37 pages, 21 figures, accepted for publication in MNRA
The Era of the Martyrs
In this book, Aaltje Hidding presents the first synthesis about how the Great Persecution (303–313 CE) was remembered in Late Antique Egypt. She unites research methods in memory studies with cognitive science and bases herself on archaeological, literary, papyrological and epigraphical sources in order to analyse how the Persecution was represented and remembered in three different cities along the Nile: Oxyrhynchus, Antinoopolis and Dendara
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