arXiv subjects

Andreas Bischof

Publications and source records attributed to Andreas Bischof.

6 recordsLinked to original sources

arXiv2025

Smart, simple, sincere - Why and how we should rethink connected things in our smart homes

More and more smart connected things and services turn our homes into smart environments. They promise comfort, efficiency and security. These devices often integrate simple sensors, e.g. for temperature, light or humidity, etc. However, these smart but yet simple sensors can pose a sincere privacy risk. The sensor data enables sense-making of home attendance, domestic activities and even health conditions, often a fact that neither users nor developers are aware of or do not know how to address. Nevertheless, not all is lost or evil. This article makes a plea for how we, the ThingsCon community, might rethink smart connected things and services in our homes. We show this in our approaches and research projects that we initiated.

cs.HC↗

arXiv2025

Superstring scattering on the real projective plane

Superstring scattering from orientifold planes requires considering string amplitudes on world-sheets with crosscaps with the lowest order case (in string coupling constant) having the topology of the real projective plane. While amplitudes on the latter have been formulated for the trivial one- and two-point cases in this work we go beyond these cases thereby solving various technicalities. The latter include reducing the complex world-sheet integration of closed string insertions over the real projective plane to pure real open string integrals. As a result we find that scattering of $n$ closed strings on the real projective plane can be expressed in terms of disk amplitudes involving $2n$ open strings. In this work we explicitly work out in pure spinor formalism the case $n=3$ which can be written as a linear combination of two (gauge-invariant) six open string amplitudes. We also present the low-energy expansion of this result necessary to construct closed string couplings on orientifold planes.

hep-th↗

arXiv2023

Scattering three closed strings off a Dp-brane in pure spinor formalism

We compute the disk amplitude of three closed strings in the pure spinor formalism. Among others, this amplitude probes tree-level gravitational interactions in the presence of Dp-branes. After disentangling holomorphic and anti-holomorphic closed string coordinates on the disk by means of introducing monodromy phases we find a compact expression for the disk amplitude of three closed strings in terms of open superstring six-point amplitudes. Furthermore, we provide the low-energy expansion (in the inverse string tension) of our amplitude and discuss some relevant Dp-brane couplings associated to it. Finally, we write down an expression for the general structure of the disk amplitude of any number n_c of closed strings in terms of pure open string amplitudes involving 2n_c open strings.

hep-th↗

arXiv2022

Wicked Implications for Human Interaction with IoT Sensor Data

Human data interaction with sensor data from smart homes can cause some implications when it comes to human sensemaking of this data. With our data-driven method Guess the Data for individual and collective data work we revealed in previous work a number of potential pitfalls when interacting with this type of data. We introduce some of the identified, often wicked implications for further discussion.

cs.HC↗

arXiv2021

Closed string disk amplitudes in the pure spinor formalism

We evaluate closed string disk amplitudes in the pure spinor formalism. We focus on low point functions (two- and one-point functions) but our analysis is also relevant for higher n-point functions. Amongst others we discuss issues arising due to the gauge fixing of the conformal Killing group of the disk and due to the zero mode prescription in the pure spinor formalism. As expected, in the end we find agreement with the known results from the RNS formalism.

hep-th↗

arXiv2018

Domain Wall Motion and Interfacial Dzyaloshinskii-Moriya Interactions in Pt/Co/Ir$(t_\mathrm{Ir})$/Ta Multilayers

The interfacial Dzyaloshinskii-Moriya interaction (DMI) is important for chiral domain walls (DWs) and for stabilizing magnetic skyrmions. We study the effects of introducing increasing thicknesses of Ir, from zero to 2 nm, into a Pt/Co/Ta multilayer between the Co and Ta. We observe a marked increase in magnetic moment, due to the suppression of the dead layer at the interface with Ta, but the perpendicular anisotropy is hardly affected. All samples show a universal scaling of the field-driven domain wall velocity across the creep and depinning regimes. Asymmetric bubble expansion shows that DWs in all of the samples have the left-handed Néel form. The value of in-plane field at which the creep velocity shows a minimum drops markedly on the introduction of Ir, as does the frequency shift of the Stokes and anti-Stokes peaks in Brillouin light scattering measurements. Despite this qualitative similarity, there are quantitative differences in the DMI strength given by the two measurements, with BLS often returning higher values. Many features in bubble expansion velocity curves do not fit simple models commonly used to date, namely a lack of symmetry about the velocity minimum and no difference in velocities at high in-plane field. These features are explained by the use of a model in which the depinning field is allowed to vary with in-plane field in a way determined from micromagnetic simulations. This theory shows that velocity minimum underestimates the DMI field, consistent with BLS returning higher values. Our results suggest that the DMI at an Ir/Co interface has the same sign as the DMI at a Pt/Co interface.

cond-mat.mes-hall↗