Coherent Quantum Ratchets Driven by Tunnel Oscillations

We demonstrate that the tunnel oscillations of a biased double quantum dot can be employed as driving source for a quantum ratchet. As a model, we use two capacitively coupled double quantum dots. One double dot is voltage biased and provides the ac force, while the other experiences the ac force and acts as coherent quantum ratchet. The current is obtained from a Bloch-Redfield master equation which ensures a proper equilibrium limit. We find that the two-electron states of the coupled ratchet-drive Hamiltonian lead to unexpected steps in the ratchet current.Comment: 4 pages, 4 figure

Nonadiabatic Electron Pumping: Maximal Current with Minimal Noise

The noise properties of pump currents through an open double quantum dot setup with non-adiabatic ac driving are investigated. Driving frequencies close to the internal resonances of the double dot-system mark the optimal working points at which the pump current assumes a maximum while its noise power possesses a remarkably low minimum. A rotating-wave approximation provides analytical expressions for the current and its noise power and allows to optimize the noise characteristics. The analytical results are compared to numerical results from a Floquet transport theory.Comment: 4 pages, 3 figures, replaced Fig. 1, added new inset in Fig. 2, extended paragraph on symmetry consideration

Transport, shot noise, and topology in AC-driven dimer arrays

We analyze an AC-driven dimer chain connected to a strongly biased electron source and drain. It turns out that the resulting transport exhibits fingerprints of topology. They are particularly visible in the driving-induced current suppression and the Fano factor. Thus, shot noise measurements provide a topological phase diagram as a function of the driving parameters. The observed phenomena can be explained physically by a mapping to an effective time-independent Hamiltonian and the emergence of edge states. Moreover, by considering quantum dissipation, we determine the requirements for the coherence properties in a possible experimental realization. For the computation of the zero-frequency noise, we develop an efficient method based on matrix-continued fractions.Comment: 8 pages, 6 figure

Nonadiabatic electron heat pump

We investigate a mechanism for extracting heat from metallic conductors based on the energy-selective transmission of electrons through a spatially asymmetric resonant structure subject to ac driving. This quantum refrigerator can operate at zero net electronic current as it replaces hot by cold electrons through two energetically symmetric inelastic channels. We present numerical results for a specific heterostructure and discuss general trends. We also explore the conditions under which the cooling rate may approach the ultimate limit given by the quantum of cooling power.Comment: 4 pages, 3 figures; published version, typos correcte

Industrial high temperature heat pump for simultaneous production of ice-water and process-heat

Industrial processes like dairy production, brewing etc. often require simultaneous cooling and heating. High temperature heat pumps (HTHP) with natural working fluids offer a cost-, energy efficient and sustainable solution. However, availability and performance data and components for HTHP are rare, which is addressed in this work. Here, the performance of a newly developed industrial scale propane-butane cascade HTHP is presented. It has a new developed semi-hermetic compressor, able to operate at high temperatures. The HTHP is installed in a Norwegian dairy and can lift from typical ice-water temperatures at 0.5°C to process hot-water at 112°C. Temperature glides are 4 K and 15 K at source and sink, respectively. Combined heating and cooling COP is 3.0 to 4.0 with a mean at 3.4 were measured. For this condition a temperature lift between heat sink and source was 88 K to 108 K. The highest temperature lift recorded between evaporation and condensation was 125 K. Condenser and evaporator capacities are within a range of 80 kW to 282 kW and 35 kW bis 134 kW, respectively. The cascade HTHP enables to utilizes waste heat form e.g. chilled/ice-water or dry-coolers effectively to supply process heat at 112°C. The HTHP is suited for a both retrofit and new installations reducing energy consumption by up to 64% and CO2-emissions by up to 94%.Industrial high temperature heat pump for simultaneous production of ice-water and process-heatacceptedVersio

Changes in the prevalence, treatment and control of hypertension in Germany? : a clinical-epidemiological study of 50.000 primary care patients

INTRODUCTION: Medical societies have developed guidelines for the detection, treatment and control of hypertension (HTN). Our analysis assessed the extent to which such guidelines were implemented in Germany in 2003 and 2001. METHODS: Using standardized clinical diagnostic and treatment appraisal forms, blood pressure levels and patient questionnaires for 55,518 participants from the cross-sectional Targets and Essential Data for Commitment of Treatment (DETECT) study (2003) were analyzed. Physician's diagnosis of hypertension (HTN(doc)) was defined as coding hypertension in the clinical appraisal questionnaire. Alternative definitions used were physician's diagnosis or the patient's self-reported diagnosis of hypertension (HTN(doc,pat)), physician's or patient's self-reported diagnosis or a BP measurement with a systolic BP≥140 mmHg and/or a diastolic BP≥90 (HTN(doc,pat,bp)) and diagnosis according to the National Health and Nutrition Examination Survey (HTN(NHANES)). The results were compared with the similar German HYDRA study to examine whether changes had occurred in diagnosis, treatment and adequate blood pressure control (BP below 140/90 mmHg) since 2001. Factors associated with pharmacotherapy and control were determined. RESULTS: The overall prevalence rate for hypertension was 35.5% according to HTN(doc) and 56.0% according to NHANES criteria. Among those defined by NHANES criteria, treatment and control rates were 56.0% and 20.3% in 2003, and these rates had improved from 55.3% and 18.0% in 2001. Significant predictors of receiving antihypertensive medication were: increasing age, female sex, obesity, previous myocardial infarction and the prevalence of comorbid conditions such as coronary heart disease (CHD), hyperlipidemia and diabetes mellitus (DM). Significant positive predictors of adequate blood pressure control were CHD and antihypertensive medication. Inadequate control was associated with increasing age, male sex and obesity. CONCLUSIONS: Rates of treated and controlled hypertension according to NHANES criteria in DETECT remained low between 2001 and 2003, although there was some minor improvement

Towards a Posthumanist Eco-Zoopoetics: Kafkas‘ Tiergeschichten and Yoko Tawadas Etüden im Schnee

The burgeoning trans-disciplinary field of (post-humanist) eco-zoopoetics is concerned with the question of how the human can represent animals and nature without ignoring their otherness. My thesis argues that literature can help readers to register this alterity by subverting the alleged readability of non-human beings. By doing this, literature sheds doubt on the human as being at the core of an anthropocentric epistemology to whom the world appears to be readable. To prove this, I will employ Uexküll’s Umweltlehre as a paradigm of reading animals and nature to discuss animal protagonists in Kafka’s Tiergeschichten, i.e. Der Bau, Forschungen eines Hundes, and Bericht für eine Akademie, and Tawada’s contemporary novel Etüden im Schnee which evokes Kafka’s animal stories. By showing that these literary texts render their creatures and their nature(s) unreadable in terms of Umweltlehre, I will introduce the Umweltlehre as a key in showing how literature can hint at non-human otherness. Reading Der Bau and Forschungen eines Hunden, the recipients as much as Kafka’s creatures fail to decipher the opaque environments to which the texts expose them even though the creatures and their readers long for it. I have chosen to call their shared futile desire of reading Umweltsehnsucht. The creatures of Der Bericht für eine Akademie and Etüden im Schnee confront the readers with a circus environment which blurs the border between a human and an animal environment. Drawing on the aesthetics of the circus and Foucault’s conception of Heterotopia, I will argue that Kafka and Tawada situate their creatures in the Hetero-Umwelt of the circus which renders its participants unreadable for the observer in terms of homogeneous environments. As a result, the circus creatures can neither be read as humans nor as animals. Instead, the readers can read them as they desire. They can acknowledge or ignore the non-human otherness of the circus creature. The circus appears to be an ambiguous place which can evoke and subvert the infantile desire of its audience to identify itself with the non-human creatures at the same time

Assessing the Solvency of Virtual Asset Service Providers: Are Current Standards Sufficient?

Entities like centralized cryptocurrency exchanges fall under the business category of virtual asset service providers (VASPs). As any other enterprise, they can become insolvent. VASPs enable the exchange, custody, and transfer of cryptoassets organized in wallets across distributed ledger technologies (DLTs). Despite the public availability of DLT transactions, the cryptoasset holdings of VASPs are not yet subject to systematic auditing procedures. In this paper, we propose an approach to assess the solvency of a VASP by cross-referencing data from three distinct sources: cryptoasset wallets, balance sheets from the commercial register, and data from supervisory entities. We investigate 24 VASPs registered with the Financial Market Authority in Austria and provide regulatory data insights such as who are the customers and where do they come from. Their yearly incoming and outgoing transaction volume amount to 2 billion EUR for around 1.8 million users. We describe what financial services they provide and find that they are most similar to traditional intermediaries such as brokers, money exchanges, and funds, rather than banks. Next, we empirically measure DLT transaction flows of four VASPs and compare their cryptoasset holdings to balance sheet entries. Data are consistent for two VASPs only. This enables us to identify gaps in the data collection and propose strategies to address them. We remark that any entity in charge of auditing requires proof that a VASP actually controls the funds associated with its on-chain wallets. It is also important to report fiat and cryptoasset and liability positions broken down by asset types at a reasonable frequency

Precooling im Rudersport und dessen Auswirkungen auf die Wettkampfleistung

Der Fakt, dass hohe Luftfeuchtigkeit und eine hohe Umgebungstemperatur die physische und psychische Leistungsfähigkeit beeinflussen, ist generell anerkannt. Dies trifft vor allem auf Sportarten zu, die dem Langzeitausdauerbereich angehören, wo hohe Temperaturen eine deutliche Beeinträchtigung hervorrufen. Ziel dieser Arbeit ist es, die Wirkung von Kälteapplikation mittels einer Kühlweste auf die Ausdauerleistungsfähigkeit bzw. die Wettkampfleistung im Rudern empirisch zu untersuchen. Die dahinter stehenden wissenschaftlichen Fragestellungen sind folgende: Kommt es durch das 30 Minuten dauernde Applizieren von Kälte mittels Kühlweste vor einem Stufentest am Ruderergometer zu einer Verbesserung der Ausdauerleistungsfähigkeit? Kommt es durch die 30 Minuten dauernde Applikation von Kälte mittels Kühlweste während des Aufwärmprozesses zu einer Verbesserung der Wettkampfleistung im 2000m All-Out-Test am Ruderergometer? Die Testverfahren, die in dieser Arbeit zur Anwendung kamen, beinhalteten das Tragen einer Kühlweste während des standardisierten und 30 Minuten dauernden Aufwärmens zum 2000m All-Out-Test oder einer 30-minütigen Kälteapplikation (Precooling), ohne Aufwärmphase, vor Beginn des Stufentests. Nach den jeweiligen Tests wurde den Athleten ein 15 Minuten langes, standardisiertes Ausrudern (Cooldown) verordnet. Um die Wirkung der Methode zu verifizieren, wurden verschiedene physiologische Parameter erfasst und einer statistischen Auswertung unterzogen. Es wurde mittels statistischer Auswertung der Untersuchungsergebnisse festgestellt, dass durch das Precooling teilweise signifikante Unterschiede bezüglich des Temperaturanstieges während des Stufentests zu verzeichnen waren. Die Entwicklung der Laktatkonzentration im Blut wies teilweise signifikante Unterschiede zugunsten des Stufentest mit Precooling auf. In Hinblick auf das Verhalten der Herzfrequenz wurden keine signifikanten Unterschiede im Stufentest festgestellt. Die 2000m Endzeiten wiesen im Mittel signifikante Unterschiede zugunsten des Wettkampftest mit Precooling auf. Weitere signifikante Unterschiede wurden beim Laktatkonzentrationsabbau während der Nachbelastung im Rahmen des 2000m All-Out- Test festgestellt. Abschließend ist festzuhalten, dass die Ausdauerleistung im Stufentest mit Precooling signifikant höher ausfiel, als beim Stufentest ohne Kälteapplikation. Es ist zu hinterfragen, warum es zu einer eventuellen Leistungssteigerung aufgrund des Precooling kommt. Dies kann Folge der Vasokonstriktion der Haut sein oder auch die psychologische Komponente, die im Sport immer eine Rolle spielt. Ferner wird auch angenommen, dass durch verschiedene Arten von Kälteapplikationen nicht das Halten einer gegebenen Geschwindigkeit oder Intensität begünstigt, sondern dass sich die Mobilisation der Reserven, die ein Athlet am Ende einer intensiven Belastung aktivieren kann oder muss, verzögert. Es wird nach Auswerten der Ergebnisse die Meinung vertreten, dass Precooling sehr wohl Einfluss auf die Leistungsfähigkeit haben kann. Vor allem die signifikante Verbesserung der Wettkampfzeit unter standardisierten Bedingungen lässt auf ein hohe Relevanz für die Arbeit im Hochleistungssport schließen.The fact that high humidity and a high surrounding temperature affects physical and psychological abilities is generally accepted (Maughan et al., 2007; Wendt et al., 2007). This is particularly true of endurance sports, where high temperatures constitute a clear impairment. (Quod et al., 2006). The goal of this thesis is empirically to investigate how applying cold with a cooling vest affects stamina in general and the ability to compete in rowing in particular. The scientific questions behind the study are the following: Does the thirty-minute application of cold using the cooling vest before a level test on the rowing machine lead to an improvement in stamina? Does the thirty-minute application of cold using the cooling vest during the warm-up process lead to an improvement in competitive abilities in the 2000m All-Out-Test on the rowing machine? The testing methods used for this thesis consist of wearing a cooling vest during the standardized, thirty-minute warm-up period for the 2000m All-Out-Test or a thirty-minute cold application (pre-cooling) without a warm-up phase before the level test. After the respective tests, the athletes were compelled to take a mandatory, standard fifteen-minute cool-down. In order to verify the effects of these methods, various physiological parameters were set and subjected to statistical analysis. Through the statistical analysis of the results of the investigation it was determined that due to the pre-cooling, significant differences regarding an increase in temperature during the level test were sometimes observed. The development of the concentration of lactate in the blood sometimes showed significant differences favoring a level test with pre-cooling. With respect to the relationship with heart frequency, no significant differences were established. The end times for the 2000m on average demonstrated significant differences favoring competitions with pre-cooling. Within the context of the 2000m All-Out-Test, additional, significant differences were demonstrated in the decomposition of the concentration of lactate during the cool-down. In conclusion, stamina in the level test with pre-cooling was significantly higher than level tests without cold application. The reasons why pre-cooling could possibly lead to an increase in stamina must be examined. It may be due to the vasoconstriction of the skin or also to the psycological components that always play a roll in sports. Furthermore, it is also assumed that the various methods of cold application do not make it easier to maintain a specific speed, rather they delay the mobilization of the reserves that an athlete can or must activate at the end of an intense strain. An analysis of the results produces the opinion that pre-cooling can definitely have an influence on stamina. In particular, the significant improvement in competition times under standard conditions suggests a higher relevance of the thesis in top-level sport

Geolocalisation of athletes for out-of-competition drug testing: ethical considerations. Position statement by the WADA Ethics Panel

Through the widespread availability of location-identifying devices, geolocalisation could potentially be used to place athletes during out-of-competition testing. In light of this debate, the WADA Ethics Panel formulated the following questions: (1) should WADA and/or other sponsors consider funding such geolocalisation research projects?, (2) if successful, could they be proposed to athletes as a complementary device to Anti-Doping Administration and Management System to help geolocalisation and reduce the risk of missed tests? and (3) should such devices be offered on a voluntary basis, or is it conceivable that they would be made mandatory for all athletes in registered testing pools? In this position paper, the WADA Ethics Panel concludes that the use of geolocalisation could be useful in a research setting with the goal of understanding associations between genotype, phenotype and environment; however, it recognises that the use of geolocalisation as part of or as replacement of whereabouts rules is replete with ethical concerns. While benefits remain largely hypothetical and minimal, the potential invasion of privacy and the data security threats are real. Considering the impact on privacy, data security issues, the societal ramifications of offering such services and various pragmatic considerations, the WADA Ethics Panel concludes that at this time, the use of geolocalisation should neither be mandated as a tool for disclosing whereabouts nor implemented on a voluntary basis