Run-and-tumble motion in a linear ratchet potential: Analytic solution, power extraction, and first-passage properties

We explore the properties of run-and-tumble particles moving in a piecewise-linear "ratchet" potential by deriving analytic results for the system's steady-state probability density, current, entropy production rate, extractable power, and thermodynamic efficiency. The ratchet's broken spatial symmetry rectifies the particles' self-propelled motion, resulting in a positive current that peaks at finite values of the diffusion strength, ratchet height, and particle self-propulsion speed. Similar nonmonotonic behaviour is also observed for the extractable power and efficiency. We find the optimal apex position for generating maximum current varies with diffusion, and that entropy production can have nonmonotonic dependence on diffusion. In particular, for vanishing diffusion, entropy production remains finite when particle self-propulsion is weaker than the ratchet force. Furthermore, power extraction with near-perfect efficiency is achievable in certain parameter regimes due to the simplifications afforded by modelling "dry" active particles. In the final part, we derive mean first-passage times and splitting probabilities for different boundary and initial conditions. This work connects the study of work extraction from active matter with exactly solvable active particle models and will therefore facilitate the design of active engines through these analytic results.Comment: 14 pages (main), 23 pages (total), 17 figure

Das Leben erzählen oder Männlichkeit und Wahrheit. Eine Gedankenfolge zu Max Frisch

The starting point of the article is Max Frisch’s desire to examine his life as a man in Montauk by the means of narration. For Frisch man’s life is characterized by certain recurring problems in his works, like history, home, or marriage. The characters in Frisch’s prose explore approaches to these problems by their trials of telling modified stories of their life. In the autobiographic narration Montauk Frisch exposes himself as a character who renounces any fiction in his search for truth. Thus, the question for the possibility of telling truth in literature emerges which is in Frisch’s case a question of the possibility of literary self-exploration. Frisch’s trial as Montauk’s narrator faces the tension between experience and memory as well as between experience and narration. The article points out that every experience gains richness in narration through the contrast to the earlier experiences which are memorized. Narration as comparison and distinction between different experiences thus becomes an instrument for Frisch’s self-exploration. But the findings still don’t suffice Frisch’s concept of truth as positions to key problems integrated in active life. Eventually the article shows that no such positions are given, but instead varied answers are given to the same questions and provide a continued approximation to what truth is according to Frisch’s concept. As those many answers to the same questions eventually provide no answer at all, the truth in Frisch’s narration is rather to be found in the untold but sketched aspects of his life as a man. Only in this game with exhibition and veiling Frisch can use literature to examine his experiences without destroying their dynamic content with their fixation in a narration. So, truth in Montauk is rather presented in the abstract form of an ongoing process of recurring questions and incessantly adjusted answers, than in the tangible form of the exposed facts about the Author’s controversial love affairs.Opowiadanie życia albo męskość i prawda. Wątek dotyczący Maxa Frischa Punktem wyjścia artykułu jest pragnienie Maxa Frischa, aby w powieści Montauk za pomocą narracji zbadać swe życie jako mężczyzny. Dla Frischa życie mężczyzny charakteryzuje się powtarzającymi się problemami w jego dziełach, takimi jak historia, dom czy małżeństwo. Postacie z prozy Frischa przedstawiają różne podejścia do tych problemów, próbując opowiadać odmienne historie o swoim życiu. W autobiograficznej narracji Montauk, Frisch ujawnia się jako postać, która w poszukiwaniu prawdy wyrzeka się jakiejkolwiek fikcji, pojawia się więc pytanie o możliwość opowiedzenia w literaturze prawdy, co w przypadku Frischa jest kwestią możliwości literackiego samozrozumienia. Wysiłek Frischa jako narratora Montauk napotyka na napięcie pomiędzy doświadczeniem i pamięcią, a także między doświadczeniem a narracją. Artykuł wskazuje, że dzięki narracji każde doświadczenie staje się dużo bogatsze  ze względu na kontrast w stosunku do zapamiętanych wcześniejszych doświadczeń. Narracja jako porównanie i rozróżnienie między różnymi doświadczeniami staje się zatem dla Frischa narzędziem samozrozumienia. W odniesieniu do stworzonego przez Frischa pojęcia prawdy uzyskane w ten sposób odkrycia nie wystarczają do ostatecznego ukazania kluczowych problemów splecionych ze sobą w aktywnym życiu. Artykuł pokazuje na koniec, że żadne takie ostateczne ukazanie problemów nie istnieje, a te same pytania otrzymują różne odpowiedzi, które pozwalają jedynie przybliżać się do prawdy tak, jak rozumie ją Frisch. Ponieważ wielość odpowiedzi na te same pytania ostatecznie okazuje się nie stanowić żadnej odpowiedzi, w narracji Frischa prawda znajduje się w nieopowiedzianych, a jedynie zarysowanych aspektach jego życia jako mężczyzny.Tylko za pomocą tej gry w ujawnianie i zasłanianie Frisch może wykorzystywać literaturę do zbadania swoich przeżyć bez niszczenia ich dynamicznej treści`, gdy zostają one utrwalone w postaci narracji. Tak więc prawda jest przedstawiana w Montauk nie tyle w konkretnej formie odsłoniętych faktów na temat kontrowersyjnych romansów autora, co raczej w abstrakcyjnej formie ciągłego procesu powtarzających się pytań i korygowanych odpowiedzi

Profitability and Data-Snooping Tests of Four Technical Trade Strategies for Cryptocurrency Pair BTC/USDT and ETH/USDT in Cryptocurrency Markets During 2022–2023

We provide a comprehensive investigation into the profitability of technical trading methods applied to the cryptocurrency pairs BTC/USDT and ETH/USDT. By employing rigorous evaluations and incremental examinations, we address the pervasive issue of data-snooping bias that often plagues the evaluation of trading strategies. Our empirical results indicate the lack of profitable technical trading strategies in both the analysis sample and prediction sample periods, even after rigorous adjustments for data snooping. These findings highlight the difficulties associated with selecting profitable technical trading strategies in the dynamic and volatile cryptocurrency market. Market participants, including individual traders, institutional investors, and regulatory bodies, should take note of our findings when making investment decisions based on technical analysis

Evaluate the blend quality of powders using a simplified mixing law

The research presents an easy to follow approach to evaluate blend quality of particle blends which are complex in shape and vary in size. For some materials simulations with discrete modelling approaches are challenging because of size and shape constrains but also of the access to recourses and knowhow of practitioners in the field using blending equipment for evaluating the blend quality of their products. A significant proportion of bulk handling operations happens in agriculture and related industries e.g. producing fertilisers, handling and storing food such as beans, lentils and rice. Different materials such as mung beans, black eye beans, lentils and rice were blended in a variable speed screw blender. The blender could vary the screw speed and then results taken from experiments were analysed to quantify the blend quality. It was found that a screw speed of 120 rpm gave the highest blend “quality” defined as a50 / 50 percent mix for different materials and blending time intervals. It was also found that the sampling position in the variable speed screw blender mattered because of axial and radial segregation occurring in the blender

Frauen Ante Portas:die Darstellung und Präsenz der weiblichen Studierenden der Universität Münster im SEMESTERSPIEGEL 1954 bis 2009

Angeregt wurde diese Arbeit durch die Mitarbeit an dem Projekt "Lasst sie doch denken! - 100 Jahre Studium für Frauen in Münster", Buch und Ausstellung darüber 2008 in Münster. Ich hatte in dem 8-köpfigen Team das Thema "Die soziale Situation der Studentin" übernommen und dafür die Studentenpresse durchgesehen. Der erste Eindruck, dass die studierenden Frauen lange Zeit kaum thematisiert wurden, obwohl ihre Zahl von 6 % im Jahre 1908 bis auf ca. 50 % heutzutage stieg, wurde durch eine quantitative Inhaltsanalyse bestätigt. Ergänzt wurden die Ergebnisse, die 55 Jahre umfassen und auch den Einfluss der Frauenbewegung zeigen, durch Zeitzeugenberichte und eigene Erfahrung (ich habe in den 1950er Jahren in Münster Germanistik, Anglistik und Publizistik studiert )

Stability Analysis of the Fluorescent Tracer 1-Methylnaphthalene for IC Engine Applications by Supercontinuum Laser Absorption Spectroscopy

1-methylnaphthalene (1-MN) is a widely used laser-induced fluorescence (LIF) tracer for planar imaging of mixture formation and temperature distributions in internal combustion (IC) engines. As the LIF measurement results can be biased by partial tracer oxidation, the conversion of 1-MN and the base fuel isooctane is analyzed in a calibration cell. First, measurements using supercontinuum laser absorption spectroscopy (SCLAS) are presented in order to quantify the conversion by detection of the produced H2O mole fraction. A single mode fiber (SMF) coupled setup is presented, with the fiber core acting as entrance slit of a Czerny-Turner spectrometer. Dependencies on residence time and global air-fuel ratio are presented at pressures up to 1.5 MPa and temperatures up to 900 K, at which distinct tracer and fuel consumption is observed. Signal loss due to intense beam steering was partially compensated using a self-stabilizing double-pass setup with a retroreflector

A dynamic model of house price

In this paper, we build the rationale of the financial intermediate's decision of making loans to potential home buyers over an infinite time horizon. In the first period "good" borrowers with stable future income flows receive loans and buy homes. In later periods, the intermediate securitizes the loans to raise new capital and makes loans to some of the "bad" borrowers with uncertain future income flows. Currently, we simplify the securitization as a tool to raise capital without cost over time. This unrealistic simplification should be improved in later work. The financial intermediate calculates the expected payoffs in different scenarios under the realizations of uncertainty to decide whether to make loans to a new borrower and whether to liquidate a house if the owner is short of liquidity in the short run. After clarifying the sequence of moves of different agents within each period, we compute the financial intermediate's decision rule described by a Bellman equation. Then we simulate borrowers' income realization and produce a figure of house price as well as value function over time