A Software Engineer’s Competencies: Undergraduate Preconceptions in Contrast to Teaching Intentions

Unlike numerous scientific disciplines, the field of engineering has rarely been subject to investigations of undergraduate pre-/misconceptions except for STEM subjects within engineering degrees. When it comes to Software Engineering, some special issues have to be taken into account (e.g. novelty of the discipline and immateriality of the product) that make this discipline hard to teach and learn. Additionally, it requires a wide range of different technical competencies as well as soft skills. As a consequence, the goal is to improve learning by using undergraduates’ “right” conceptions as “points of departure” and reduce learning obstacles by facing misconceptions. This paper is giving some first insights into a quantitative study conducted with undergraduates – before and after instruction – as well as two professors using a questionnaire to rate Software Engineering competencies to elicit preconceptions

Konstruktion eines 3D-Bildstanzers

Im Zuge des Lego-Projekts an der Otto-von-Guericke-Universit¨at Magdeburg im WS 18/19 wurde ein Bildstanzer mittels Lego® mindstorms® NXT 2.0 konstruiert und mit Hilfe von MATLAB programmiert. Der Bildstanzer erlaubt es, eine zweidimensionale, graue Rastergraphik in ein dreidimensionales Bild zu verwandeln, dessen Eindrucktiefe dem jeweiligen Grauton entspricht. Als Bearbeitungsmaterial wurde aufgrund seiner Eigenschaften Blumenschaum verwendet. ImZuge der Entwicklung konnten die Pixeldichte von 10x15 px und die Geschwindigkeit des Vorgangs auf das Doppelte erh¨oht werden und erlauben nun eine Abbildung von 20x30 px in 12 min

Scanning Gate Microscopy of Localized States in a gate-defined Bilayer Graphene Channel

We use Scanning Gate Microscopy to demonstrate the presence of localized states arising from potential inhomogeneities in a 50nm-wide, gate-defined conducting channel in encapsulated bilayer graphene. When imaging the channel conductance under the influence of a local tip-induced potential, we observe ellipses of enhanced conductance as a function of the tip position. These ellipses allow us to infer the location of the localized states and to study their dependence on the displacement field. For large displacement fields, we observe that localized states tend to occur halfway into the channel. All our observations can be well explained within the framework of stochastic Coulomb blockade

Superballistic electron flow through a point contact in a Ga[Al]As heterostructure

We measure electronic transport through point contacts in the high-mobility electron gas in a Ga[Al]As heterostructure at different temperatures and bulk electron densities. The conductance through all point contacts increases with increasing temperature in a temperature window around $T \sim 10 K$ for all investigated electron densities and point contact widths. For high electron densities this conductance exceeds the fundamental ballistic limit (Sharvin limit). These observations are in agreement with a viscous electron transport model and previous experiments in graphene.Comment: 5 pages, 2 figure

Shell Filling and Trigonal Warping in Graphene Quantum Dots

Transport measurements through a few-electron circular quantum dot in bilayer graphene display bunching of the conductance resonances in groups of four, eight and twelve. This is in accordance with the spin and valley degeneracies in bilayer graphene and an additional threefold 'minivalley degeneracy' caused by trigonal warping. For small electron numbers, implying a small dot size and a small displacement field, a two-dimensional s- and then a p-shell are successively filled with four and eight electrons, respectively. For electron numbers larger than twelve, as the dot size and the displacement field increase, the single-particle ground state evolves into a three-fold degenerate minivalley ground state. A transition between these regimes is observed in our measurements and can be described by band-structure calculations. Measurements in magnetic field confirm Hund's second rule for spin filling of the quantum dot levels, emphasizing the importance of exchange interaction effects.Comment: 10 pages, 7 figure

Imaging signatures of the local density of states in an electronic cavity

We use Scanning Gate Microscopy to study electron transport through an open, gate-defined resonator in a Ga(Al)As heterostructure. Raster-scanning the voltage-biased metallic tip above the resonator, we observe distinct conductance modulations as a function of the tip-position and voltage. Quantum mechanical simulations reproduce these conductance modulations and reveal their relation to the partial local density of states in the resonator. Our measurements illustrate the current frontier between possibilities and limitations in imaging the local density of states in buried electron systems using scanning gate microscopy

Kondo effect and spin-orbit coupling in graphene quantum dots

The Kondo effect is a cornerstone in the study of strongly correlated fermions. The coherent exchange coupling of conduction electrons to local magnetic moments gives rise to a Kondo cloud that screens the impurity spin. Whereas complete Kondo screening has been explored widely, realizations of the underscreened scenario - where only some of several Kondo channels participate in the screening - remain rare. Here we report the observation of fully screened and underscreened Kondo effects in quantum dots in bilayer graphene. More generally, we introduce a unique platform for studying Kondo physics. In contrast to carbon nanotubes, whose curved surfaces give rise to strong spin-orbit coupling breaking the SU(4) symmetry of the electronic states relevant for the Kondo effect, we study a nominally flat carbon material with small spin-orbit coupling. Moreover, the unusual two-electron triplet ground state in bilayer graphene dots provides a route to exploring the underscreened spin-1 Kondo effect

Using rapid point-of-care tests to inform antibiotic choice to mitigate drug resistance in gonorrhoea

Background: The first cases of extensively drug resistant gonorrhoea were recorded in the United Kingdom in 2018. There is a public health need for strategies on how to deploy existing and novel antibiotics to minimise the risk of resistance development. As rapid point-of-care tests (POCTs) to predict susceptibility are coming to clinical use, coupling the introduction of an antibiotic with diagnostics that can slow resistance emergence may offer a novel paradigm for maximising antibiotic benefits. Gepotidacin is a novel antibiotic with known resistance and resistance-predisposing mutations. In particular, a mutation that confers resistance to ciprofloxacin acts as the ‘stepping-stone’ mutation to gepotidacin resistance. Aim: To investigate how POCTs detecting Neisseria gonorrhoeae resistance mutations for ciprofloxacin and gepotidacin can be used to minimise the risk of resistance development to gepotidacin. Methods: We use individual-based stochastic simulations to formally investigate the aim. Results: The level of testing needed to reduce the risk of resistance development depends on the mutation rate under treatment and the prevalence of stepping-stone mutations. A POCT is most effective if the mutation rate under antibiotic treatment is no more than two orders of magnitude above the mutation rate without treatment and the prevalence of stepping-stone mutations is 1–13%. Conclusion: Mutation frequencies and rates should be considered when estimating the POCT usage required to reduce the risk of resistance development in a given population. Molecular POCTs for resistance mutations and stepping-stone mutations to resistance are likely to become important tools in antibiotic stewardship