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As a result of the pandemic, many physics courses moved online. Alongside, the popularity of internet-based problem-solving sites and forums rose. With the emergence of Large Language Models, another shift occurred. One year into the public availability of these models, how has online help-seeking behavior among introductory physics students changed, and what is the effect of different patterns of online-resource usage? In a mixed-method approach, we investigate student choices and their impact on assessment components of an online introductory physics course for scientists and engineers. We find that students still mostly rely on traditional internet resources, and that their usage strongly influences the outcome of low-stake unsupervised quizzes. However, we also find that the impact of different help-seeking patterns on the supervised assessment components of the course is non-significant.

Purpose: In the recent past, spin-locking MRI experiments were successfully applied for the direct detection of sinusoidal magnetic field oscillations in the sub-nT range. In the present study, this detection approach was extended to non-sinusoidal pulsed magnetic fields based on the Rotary Excitation (REX) mechanism. Methods: The new detection concept was examined by means of Bloch simulations, evaluating the interaction effect of spin-locked magnetization and low-frequency pulsed magnetic fields. The REX detection approach was validated under controlled conditions in phantom experiments at 3T. Gaussian and Sinc-shaped stimuli were investigated. In addition, the detection of artificial fields resembling a cardiac QRS complex, which is the most prominent peak visible on a Magnetocardiogram, was tested. Results: Bloch simulations demonstrated that the REX method has a high sensitivity to pulsed fields in the resonance case, which is met when the spin-lock frequency coincides with a non-zero Fourier component of the stimulus field. In the experiments, we found that magnetic stimuli of different durations and waveforms can be distinguished by their characteristic REX response spectrum. The detected REX amplitude was proportional to the stimulus peak amplitude (R2>0.98) and the lowest field detection was 1 nT. Furthermore, the detection of QRS-like fields with varying QRS durations yielded significant results in a phantom setup (p<0.001). Conclusion: REX detection can be transferred to non-sinusoidal pulsed magnetic fields and could provide a non-invasive, quantitative tool for spatially resolved assessment of cardiac biomagnetism. Potential applications include the direct detection and characterization of cardiac conduction., Comment: Figures: 9 Figures Pages: 26 Address for correspondence: Petra Albertova, University of W\"urzburg, Experimental Physics 5, Am Hubland, W\"urzburg, DE D-97074, petra.albertova@uni-wuerzburg.de Submitted to Magnetic Resonance in Medicine

At large institutions of higher education, students frequently have a choice whether to attend the introductory physics sequence asynchronously online, on-site in a traditional lecture-setting, or in a reformed studio setting. In this study, we investigate how these different settings are correlated with measures of self-efficacy, interest in physics, and success in subsequent physics and engineering courses, which have the introductory physics sequence as prerequisites. As previous research indicates, some of these measures may depend on gender. We found that the course setting had no significant correlation with the grade in subsequent courses, but that studio-settings gave students the feeling of being better prepared, particularly for subsequent courses that included laboratory or recitation components. We also found that gender was correlated with measures of interest in physics, where female students expressed significantly less interest in the subject, regardless of course setting.

We show that an ensemble of thermally weakly coupled geometrically frustrated systems (GFSs), which are constraint to reside at negative Boltzmann temperatures, is in equilibrium cooler than its constituents, and may even exhibit positive temperatures at low energies. The challenge for the second law of thermodynamics arising from potential heat flow related to the Boltzmann temperature gradient between a GFS and its ensemble is resolved by considering the energy fluctuations above the ground state, i.e. the most probable state of a GFS. They are comprised in the canonical temperature, derived from information theory. Whereas the Boltzmann temperature gradient reveals the direction of the stochastic drift of the most probable state of a GFS within its ensemble, canonical temperature gradients define that of heat flow., Comment: 8 pages, 2 Figures plus Appendix 5 pages 5 Figures

Recent technical advancements allow cardiac MRI (CMR) examinations in the presence of so-called MRI conditional active cardiac implants at 3.0T. However, the artifact burden caused by susceptibility effects remain an obstacle. All measurements were obtained at a clinical 3.0T scanner using an in-house designed cubic phantom and optimized sequences for artifact evaluation (3D gradient echo sequence, multi-slice 2D turbo spin echo sequence), as well as reference sequences according to the ASTM were applied. Four representative active cardiac devices and a generic setup were analysed regarding volume and shape of the signal void. For analysis, a threshold operation applied to the grey value profle of each data data set was used. The presented approach allows the evaluation of signal void and shape even for larger implants such as ICDs. The void shape is influenced by the orientation of the B0-field and the chosen sequence type, as well as the distribution of magnetic material within the implants. The void volume depends both on the device itself, and the sequence type. Disturbances in the B0 and B1 fields exceed the visual signal void. This work presents a reproducible and highly defined approach towards characterising both signal void artifacts at 3.0T and their influencing factors., Comment: Keywords: Artifacts, CMR, 3.0T, active implants, signal void

Although Boltzmann's definition of entropy, and, hence, the existence of negative temperatures, are widely accepted, we will show scenarios which apparently at a first glance are inconsistent with our normal notion of thermodynamics. This is shown in the framework of stochastic thermodynamics for special geometrical frustrated systems (GFSs), which have maximum entropy at its ground state and constant negative temperature. For two GFSs in weak thermal contact and at same temperature, all energetic constellations are equal probable. A hot and a cool GFS in contact is driven by entropic forces via heat transfer to a most probable state in which the hot GFS is in its ground state. The same holds for a GFS in contact with a gas. As this is not a local maximum of entropy both subsystems maintain different temperatures here. Re-parametrization can transform these non-local into local maxima with corresponding equivalence of re-defined temperatures. However, these temperatures cannot be assigned solely to a subsystem but describe combinations of both.The non-local maxima of entropy restrict the naive application of the zeroth law of thermodynamics. Reformulated this law is still valid with the consequence that a GFS at constant negative temperature can measure positive temperatures. A GFS combined with a polarized paramagnetic spin gas may have a local or non-local maxima of entropy, with equivalent or non-equivalent temperatures, respectively. In case of a local maximum the spin gas can measure the temperature of the GFS, however, it does not reveal information about its energetic state., Comment: 13 pages, 4 Figures

The progressive digitalization is changing the way businesses work and interact. Concepts like Internet of Things, Cloud Computing, Industry 4.0, Service 4.0, Smart Production or Smart Cities are based on systems that are linked to the Internet. The online access to the provided data creates potential to optimize processes and cost reductions, but also exposes it to a risk for an inappropriate use. Trust management systems are necessary in terms of data security, but also to assure the trustworthiness of data that is distributed. Fake news in social media is an example for problems with online data that is not trustable. Security and trustworthiness of data are major concerns today. The speed in digitalization makes it even a greater challenge for future research. This article introduces therefore a model of online trust content usable to compute the trust of an online service advertisement. It contributes to standardize business service descriptions necessary to realize visions of E-commerce 4.0, because it is the basis for the development of AI systems that are able to match an service request to a service advertisement. It is necessary for building trust enhancing architectures in B2B e-commerce. To do so, we conducted case studies, analysed websites, developed a prototype system and verified it by conducting expert interviews., Comment: 12 pages, 16 figures

We present a rigorous mathematical approach of two species channel transport within the framework of stochastic thermodynamics, which explains the impact of interparticle in-channel interactions. Different from mean field approaches, the model explicitly conserves spatial correlations by considering stochastic transitions between the channel's occupation states. The interparticle interactions determine the Brownian ratchet like rectifying forces, which these species exert mutually on each other. Perfect coupling of transport emerges by an attractive empty channel and strong repulsive forces between particles of the same species. Stochastic transitions are then confined to a subspace with circular topology, which makes channel flows of both species become equivalent. For opposing concentration gradients, this makes the species with the stronger gradient the driving, positive entropy producing one, the other is driven and produces negative entropy. A differential interaction with less repulsive forces within particles of one species, but maintenance of this interaction for the other species, adds a bypass path to this circular subspace. On this path a leak flow of the species with less repulsive interparticle interaction emerges, which is directed parallel to its concentration gradient, and, hence, produces positive entropy. Now, appropriate strong opposing concentration gradients may simultaneously parallelize flow of their respective species, which makes each species produce positive entropy. The rectifying potential of the species with the bypass option is diminished, which implies the existence of a gradient of the other species, above which its flow and gradient are always parallel. Conversely flow of the less coupled species may always be turned anti-parallel to its gradient by a sufficient strong opposing gradient of the other one., Comment: 23 pages 10 Figures

Flow of particles of two different species through a narrow channel with solely two discrete spatial positions is analyzed with respect to the species' capability to cooperate or compete for transport. In contrast to mean field approaches, spatial correlations are explicitly conserved. A strong repulsive interaction between particles of the same kind and a very attractive channel imply a strong entanglement of transport of both species. This is reflected by the magnitude of transition flows in state space which in the extreme case of perfect coupling are restricted to a cyclic sub space. Entanglement of transport implies that the species mutually exert entropic forces on each other. For parallel directed concentration gradients this implies that the species' ability to cooperate increases with the degree of entanglement. Thus, the gradient of one species reciprocally induce a higher flow of the other species when compared to that in its absence. The opposite holds for antiparallel gradients where species mutually hamper their transport. For a sufficient strong coupling, the species under the influence of the stronger concentration gradient drives the other against its gradient, i.e. flow and gradient of the driven species become antiparallel. Hence, besides the positive entropy production generated by the driving species a negative component of entropy production of the driven species emerges. The sources of both, positive and negative entropy production, can be localized in state space. The stronger the coupling of transport the higher is the degree of efficiency, i.e. the amount of negative entropy production on cost of the positive one.