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Cyclic Superconducting Refrigerators Using Guided Fluxon Propagation
Get PDFWe propose cyclic refrigeration in solid state, employing a gas of magnetic field vortices in a type-II superconductor—also known as fluxons—as the cooling agent. Refrigeration cycles are realized by envisioning a racetrack geometry consisting of both adiabatic and isothermal arms, etched into a type-II superconductor. The guided propagation of fluxons in the racetrack is achieved by applying an external electrical current, in a Corbino geometry, through the sample. A gradient of magnetic field is set across the racetrack allowing one to adiabatically cool down and heat up the fluxons, which subsequently exchange heat with the cold and hot reservoirs, respectively. We characterize the steady state of refrigeration cycles thermodynamically for both s-wave and d-wave pairing symmetries, and present their figures of merit such as the cooling power delivered, and the coefficient of performance. Our cooling principle can offer significant cooling for on-chip microrefrigeration purposes, by locally cooling below the base temperatures achievable in a conventional dilution refrigerator. We estimate nW/mm2 of cooling power per unit area assuming a tunnel coupling with ∼MΩµm2 specific resistance. Integrating the fluxon fridge to quantum circuits can enhance their coherence time by locally suppressing thermal fluctuations, and improve the efficiency of single photon detectors and charge sensors
Pseudo-differential Operators on the Circle, Bernoulli Polynomials
Get PDFWe show how the classical polylogarithm function Lis (z) and its relatives, the Hurwitz zeta function and the Lerch function are all of a spectral nature, and can explain many properties of the complex powers of the Laplacian on the circle and of the distribution (x +i0)s .We also make a relation with a result of Keiper [Fractional Calculus and its relationship to Riemann’s zeta function, Master of Science, Ohio State University, Mathematics (1975)]
Annual Research Review: The Power of Predictability – Patterns of Signals in Early Life Shape Neurodevelopment and Mental Health Trajectories
Get PDFThe global burden of early life adversity (ELA) is profound. The World Health Organization has estimated that ELA accounts for almost 30% of all psychiatric cases. Yet, our ability to identify which individuals exposed to ELA will develop mental illness remains poor and there is a critical need to identify underlying pathways and mechanisms. This review proposes unpredictability as an understudied aspect of ELA that is tractable and presents a conceptual model that includes biologically plausible mechanistic pathways by which unpredictability impacts the developing brain. The model is supported by a synthesis of published and new data illustrating the significant impacts of patterns of signals on child development. We begin with an overview of the existing unpredictability literature, which has focused primarily on longer patterns of unpredictability (e.g. years, months, and days). We then describe our work testing the impact of patterns of parental signals on a moment-to-moment timescale, providing evidence that patterns of these signals during sensitive windows of development influence neurocircuit formation across species and thus may be an evolutionarily conserved process that shapes the developing brain. Next, attention is drawn to emerging themes which provide a framework for future directions of research including the evaluation of functions, such as effortful control, that may be particularly vulnerable to unpredictability, sensitive periods, sex differences, cross-cultural investigations, addressing causality, and unpredictability as a pathway by which other forms of ELA impact development. Finally, we provide suggestions for prevention and intervention, including the introduction of a screening instrument for the identification of children exposed to unpredictable experiences
A Conversation about the US 2024 Presidential Elections: Staying Engaged in our Democracy
No full textJoin us online to discuss the importance of staying engaged in our democracy during an election year. What can we do in our roles as educators and supporters of education to encourage a better understanding of civics and U.S. history?
Join moderator Fred Smoller for a conversation with two former representatives on reframing political discourse to focus on issues and minimizing political rhetoric
No, Not Even Water : A DEI Approach to Embracing Ramadan\u27s Richness
Get PDFAs Ramadan commences tomorrow, March 11, 2024, it presents a unique opportunity for both observant Muslims and those from other faiths or practices to come together in a period marked by reflection, renewal, and community. This sacred month offers a window into the discipline and devotion of fasting from dawn until dusk, underscoring values of empathy, gratitude, and solidarity with those less fortunate. For non-Muslims, it\u27s an opportunity to learn about and respect these practices, perhaps by participating in communal Iftars, engaging in dialogue, or simply offering support and understanding to those observing the fast. By embracing the spirit of Ramadan, we can all contribute to an atmosphere of inclusivity and mutual respect, fostering stronger bonds within our diverse communities. Let us welcome this month with open hearts and minds, ready to discover and share in the rich tapestry of experiences it brings
DNA Barcoding Methodologies for the Identification of Fish Species in Cooked Products
Get PDFDeoxyribonucleic acid (DNA) barcoding is a sequencing-based method that utilizes a standardized genetic region to identify species in combination with a reference database. DNA barcoding methodologies have been extensively applied to the identification of species in cooked seafood. While the typical genetic target associated with DNA barcoding is a ~650-bp region of the gene coding for cytochrome (cyt) c oxidase subunit I (COI), additional genetic targets include partial regions of the cyt b and 16S ribosomal ribonucleic acid (rRNA) genes. Most categories of cooked seafood can be identified using ~400- to 700-bp regions of these genes; however, canned seafood and other heavily processed products often require shorter regions of DNA, termed “mini-barcodes.” Metabarcoding is an emerging technique that allows for the identification of seafood species mixtures. The objective of this book chapter was to provide an overview of the application of DNA barcoding methodologies for the identification of seafood species in cooked products.https://digitalcommons.chapman.edu/food_science_books/1002/thumbnail.jp
Methionyl-tRNA Synthetase Synthetic and Proofreading Activities are Determinants of Antibiotic Persistence
Get PDFBacterial antibiotic persistence is a phenomenon where bacteria are exposed to an antibiotic and the majority of the population dies while a small subset enters a low metabolic, persistent, state and are able to survive. Once the antibiotic is removed the persistent population can resuscitate and continue growing. Several different molecular mechanisms and pathways have been implicated in this phenomenon. A common mechanism that may underly bacterial antibiotic persistence is perturbations in protein synthesis. To investigate this mechanism, we characterized four distinct metG mutants for their ability to increase antibiotic persistence. Two metG mutants encode changes near the catalytic site of MetRS and the other two mutants changes near the anticodon binding domain. Mutations in metG are of particular interest because MetRS is responsible for aminoacylation both initiator tRNAMet and elongator tRNAMet indicating that these mutants could impact translation initiation and/or translation elongation. We observed that all the metG mutants increased the level of antibiotic persistence as did reduced transcription levels of wild type metG. Although, the MetRS variants did not have an impact on MetRS activity itself, they did reduce translation rates. It was also observed that the MetRS variants affected the proofreading mechanism for homocysteine and that these mutants’ growth is hypersensitive to homocysteine. Taken together with previous findings, our data indicate that both reductions in cellular Met-tRNAMet synthetic capacity and reduced proofreading of homocysteine by MetRS variants are positive determinants for bacterial antibiotic persistence