Optimal quantum interference thermoelectric heat engine with edge states

We show theoretically that a thermoelectric heat engine, operating exclusively due to quantum-mechanical interference, can reach optimal linear-response performance. A chiral edge state implementation of a close-to-optimal heat engine is proposed in an electronic Mach-Zehnder interferometer with a mesoscopic capacitor coupled to one arm. We demonstrate that the maximum power and corresponding efficiency can reach 90\% and 83\%, respectively, of the theoretical maximum. The proposed heat engine can be realized with existing experimental techniques and has a performance robust against moderate dephasing.Comment: 5 pages, 3 figures, published versio

What does beef taste like?

Today, there is no general terminology to describe the sensory properties of beef. Hence, the aim of this study was to develop a terminology to describe the sensory texture, flavour and appearance properties of beef. Attributes describing beef were chosen from earlier studies and a qualitative open discussion. The sensory quantitative method that were used to validate the words chosen from the open discussion were CATA, “Catch-all-that-apply” with 30 respondents. Colour- and pH measurements were also performed to see if there were any significant differences between the meat samples and if there were any correlations between pH and colour values and the generated terminology. The muscle that was analyzed were Strip Loin (M. longissimus dorsi) from four cattle. The terminology established by the 30 respondents generated 7 texture-, 7 flavour- and 9 appearance attributes. The most common flavour attributes, that over 50 percent of the panelists seemed to perceive in at least one of the four meat samples during the sensory method CATA, were umami, mineral, moderate meaty, nutty, buttery, mellow and mature. The texture and appearance attributes generated in the same way was juicy, tough, tender, firm, soft, dense- and porous fiber structure, clear and dark red, homogeneous colour, poorly-, moderate- and richly marbled, fibery, moist and smooth. The pH analysis showed no statistical difference between the samples. The colour analysis on the other hand did show a statistical difference. Any correlation between the terminology and the obtained values from pH and colour measurements could not be found.Idag finns det ingen generell terminologi för att beskriva de sensoriska egenskaperna för nötkött. Målet med denna studie var att utveckla en terminologi för att beskriva den sensoriska texturen, smaken och utseendet av nötkött. Attributen som valdes för att beskriva köttet hade sitt ursprung från tidigare studier och en kvalitativ öppen diskussion. Den sensoriska kvantitativa metoden som användes för att validera orden valda från den öppna diskussionen var CATA, ”Catch-all-that-apply” med 30 respondenter. pH- och färgmätningar utfördes även för att se om det var några signifikanta skillnader mellan proven och om det fanns några korrelationer mellan pH- och färgresultat samt den genererade terminologin. Muskeln som analyserades var ryggbiff (M. longissimus dorsi) från fyra nötkreaturdjur. Terminologin som fastställdes av de 30 respondenterna genererade 7 textur-, 7 smak- och 9 utseendeattribut. De vanligaste smakattributen som över 50 procent av panellisterna tyckte sig känna i minst ett av de fyra köttproven under den sensoriska CATA-metoden var umami, mineral, måttlig köttsmak, nötig, smörig, mogen och mustig. De texturattribut som genererades på samma sätt var saftig, seg, mör, fast, mjuk, tät- och gles/porös fiberstruktur. Utseendeattributen som genererades var klarröd, mörkröd, homogen färg, svagt-, måttligt-, och rikligt marmorerad, fuktig, fibrig och slät. pH analysen visade inte på någon statistiskt signifikant skillnad mellan köttet från de olika proverna, medan färganalysen gjorde det. Någon korrelation mellan terminologin och de erhållna pH- och färgvärdena kunde inte hittas

How young children’s play is shaped through common iPad applications: a study of 2 and 4–5 year-olds

Digital devices such as iPads are prevalent in children’s play from an early age. How this shapes young children’s play is an area of considerable debate without any clear consensus on how different forms of play are brought into the iPad interaction. In this study, we examined 98 play activities of children in two preschool settings, featuring 2 and 4–5-year-olds, their play with iPads and non-digital artefacts. Three analytical approaches were used: an index built on a digital play framework [Bird, Jo, and Susan Edwards. 2015. “Children Learning to Use Technologies Through Play: A Digital Play Framework.” British Journal of Educational Technology 46 (6): 1149–1160. doi:10.1111/bjet.12191 ], a quantitative description of the index, and a qualitative interaction analysis of children’s play. Results show how play with iPads is characterised as less ludic than play with other artefacts, and diverges from the age-typical norms of play. We discuss what these results might mean for children’s play in contemporary early childhood settings and for children’s learning

Microbiota flow from milk to cheese, based on pasteurized and non-pasteurized milk

Denna studie är gjord i samarbete med Mattas gårdsmejeri som ligger beläget i Sund på Åland. Mjölk, ostmassa och lagrad vitmögelost, både pastöriserad och opastöriserad från samma mjölkbatch insamlades från mejeriet. Dessa mejeriprodukter undersöktes med avseende på dess mikrobiota. Parametrarna som undersöktes var mängden totala antal bakterier och stafylokockerbakterier. Dessa bakterier samt mjölksyrabakterier identifierades sedan i Maldi ToF MS. Även en pH-mätning av ostmassan under och efter ystningen utfördes. Den pastöriserade ostmassan visade sig ha cirka 101cfu ml-1-enheter lägre bakteriehalt jämfört med den opastöriserade ostmassan. Den pastöriserade mjölken hade 102 cfu ml-1- enheter lägre bakteriehalt jämfört med den opastöriserade mjölken. Den pastöriserade och den opastöriserade ostmassan hade ungefär samma pH-sänkning på 1,4 enheter ett dygn efter ystningen. Efter att vitmögelosten lagrats i fyra veckor hade bakteriehalten sjunkit med 102 cfu ml-1-enheter för den opastöriserade osten medan den pastöriserade osten hade sjunkit med 103 cfu ml-1-enheter. Bakterierna som identifierades i den pastöriserade ostmassan var Stafylokocker warneri, Stafylokocker pasteuri, Stafylokocker epidermidid, Leunostoc pseudomesenteroides och Leunostoc mesenteroides. I den opastöriserad ostmassan hittades Stafylokocker warneri, Stafylokocker chromogenes, Proteus mirabilis och Leunostoc pseudomesenteroides. I den opastöriserade mjölken från kyltank så identifierades Stafylokocker warneri, Stafylokocker chromogenes, Aerococcus viridans och Rhodotorula mucilaginosa. Slutligen så hittades endast Stafylokocker aureus och Leuconostoc pseudomesenteroides i den fyra veckor lagrade vitmögelosten.This study was conducted in collaboration with Mattas dairy farm, located in Sund on Åland islands. Milk, curd and maturated white mould cheese, both pasteurized and unpasteurized from the same milk batch were collected from the dairy. These dairy products were examined for its microbiota. The parameters investigated were the amount of total bacteria and Staphylococcus bacteria. These bacteria as well as lactic acid bacteria were then identified in Maldi ToF MS. A pH measurement of the curd during and after the curdling was also performed. The pasteurized curd was found to have approximately 101cfu ml-1 units lower bacterial content compared with the unpasteurized curd. The pasteurized milk had 102 cfu ml-1 units lower bacterial content compared with the unpasteurized milk. The pasteurized and unpasteurized curd had approximately the same pH decrease of 1.4 units one day after the curdling. After the white mould cheese was stored for four weeks the bacterial content decreased with 102 cfu ml-1 units for the unpasteurized cheese while the pasteurized cheese had fallen with 103 cfu ml-1 units. The bacteria identified in the pasteurized curd were Stafylococcus warneri, Stafylococci pasteuri, Stafylococcus epidermidid, Leunostoc pseudomesenteroides and Leunostoc mesenteroides. In the unpasteurized curd, Stafylococcus warneri, Stafylococcus chromogenes, Proteus mirabilis and Leunostoc pseudomesenteroides were found. In the unpasteurized milk from the cooling tank, Stafylococcus warneri, Stafylococcus chromogenes, Aerococcus viridans and Rhodotorula mucilaginosa were identified. Finally, only Stafylococcus aureus and Leuconostoc pseudomesenteroides were found in the four-week-old white mould cheese

Minimal-excitation single-particle emitters: A comparison of charge and energy transport properties

We investigate different types of time-dependently driven single-particle sources whose common feature is that they produce pulses of integer charge and minimally excite the Fermi sea. These sources are: a slowly driven mesoscopic capacitor, a Lorentzian-shaped time-dependent bias voltage, and a local gate-voltage modulation of a quantum Hall edge state. They differ by their specific driving protocols, e.g., they have a pure ac driving or a driving with a dc component. In addition, only in the first of these setups, strong confinement leading to a discrete energy spectrum of the conductor, is exploited for the single-particle emission. Here, we study if and how these basic differences impact transport properties. Specifically, we address time- and energy-resolved charge and energy currents, as well as their zero-frequency correlators (charge-, energy- and mixed noise), as they are frequently used to characterize experiments in quantum optics with electrons. Beyond disparities due to a different number and polarity of particles emitted per period, we in particular identify differences in the impact, which temperature has on the observables for sources with and without energy-dependent scattering properties. We trace back these characteristics to a small set of relevant parameter ratios.Comment: 20 pages, 8 figure

What Matters in Professional Drone Pilots’ Practice? An Interview Study to Understand the Complexity of Their Work and Inform Human-Drone Interaction Research

Human-drone interaction is a growing topic of interest within HCI research. Researchers propose many innovative concepts for drone applications, but much of this research does not incorporate knowledge on existing applications already adopted by professionals. This limits the validity of said research. To address this limitation, we present our fndings from an in-depth interview study with 10 professional drone pilots. Our participants were armed with signifcant experience and qualifcations - pertinent to both drone operations and a set of applications covering diverse industries. Our fndings have resulted in design recommendations that should inform both ends and means of human-drone interaction research. These include, but are not limited to: safety-related protocols, insights from domain-specifc use cases, and relevant practices outside of hands-on fight

Screening effects in the interplay between thermoelectric response and time-dependent driving

We investigate a coherent conductor, which is voltage- and temperature-biased and additionally fed by a time-dependently driven single-particle source (SPS). The conductor has an energy-dependent transmission that we propose to be realized by a quantum point contact (QPC). The interplay between stationary biases and time-dependent driving results in (quantum) screening effects at the QPC, which are already visible in the linear thermoelectric response coefficients of the conductor to small biases and which can literally be switched on and off by the presence or absence of the time-dependent driving. We find that this effect opens up for two very different opportunities for spectroscopy: (1) the linear-response coefficients modified by the source operation give direct access to rather unexplored quantum screening effects, which in other types of devices are obscured by geometric capacitive effects and only constitute negligibly small corrections. At the same time, (2) the tunable screening corrections to the linear-response coefficients are related to the energetic properties of the SPS, providing a direct experimental characterization tool for the SPS properties

Power, Efficiency and Fluctuations in a Quantum Point Contact as Steady-State Thermoelectric Heat Engine

The trade-off between large power output, high efficiency and small fluctuations in the operation of heat engines has recently received interest in the context of thermodynamic uncertainty relations (TURs). Here we provide a concrete illustration of this trade-off by theoretically investigating the operation of a quantum point contact (QPC) with an energy-dependent transmission function as a steady-state thermoelectric heat engine. As a starting point, we review and extend previous analysis of the power production and efficiency. Thereafter the power fluctuations and the bound jointly imposed on the power, efficiency, and fluctuations by the TURs are analyzed as additional performance quantifiers. We allow for arbitrary smoothness of the transmission probability of the QPC, which exhibits a close to step-like dependence in energy, and consider both the linear and the non-linear regime of operation. It is found that for a broad range of parameters, the power production reaches nearly its theoretical maximum value, with efficiencies more than half of the Carnot efficiency and at the same time with rather small fluctuations. Moreover, we show that by demanding a non-zero power production, in the linear regime a stronger TUR can be formulated in terms of the thermoelectric figure of merit. Interestingly, this bound holds also in a wide parameter regime beyond linear response for our QPC device

Helicobacter suis binding to carbohydrates on human and porcine gastric mucins and glycolipids occurs via two modes

Helicobacter suis colonizes the stomach of most pigs and is the most prevalent non-Helicobacter pylori Helicobacter species found in the human stomach. In the human host, H. suis contributes to the development of chronic gastritis, peptic ulcer disease and MALT lymphoma, whereas in pigs it is associated with gastritis, decreased growth and ulcers. Here, we demonstrate that the level of H. pylori and H. suis binding to human and pig gastric mucins varies between individuals with species dependent specificity. The binding optimum of H. pylori is at neutral pH whereas that of H. suis has an acidic pH optimum, and the mucins that H. pylori bind to are different than those that H. suis bind to. Mass spectrometric analysis of mucin O-glycans from the porcine mucin showed that individual variation in binding is reflected by a difference in glycosylation; of 109 oligosaccharide structures identified, only 14 were present in all examined samples. H. suis binding to mucins correlated with glycans containing sulfate, sialic acid and terminal galactose. Among the glycolipids present in pig stomach, binding to lactotetraosylceramide (Gal beta 3GlcNAc beta 3Gal beta 4Glc beta 1Cer) was identified, and adhesion to Gal beta 3GlcNAc beta 3Gal beta 4Glc at both acidic and neutral pH was confirmed using other glycoconjugates. Together with that H. suis bound to DNA (used as a proxy for acidic charge), we conclude that H. suis has two binding modes: one to glycans terminating with Gal beta 3GlcNAc, and one to negatively charged structures. Identification of the glycan structures H. suis interacts with can contribute to development of therapeutic strategies alternative to antibiotics