Phonon Mechanisms for Excess Heat Capacity in Membrane Isolated Superconducting Transition Edge Sensors

The mechanics of phonon transport in membrane-isolated superconducting transition edge sensors is discussed. Surveys of the literature on this type of sensor reveal a number of designs with excess heat capacity and a smaller subset that exhibit decoupling of the superconducting film from the underlying dielectric. A simple model is addressed in which the membrane, despite its thermal isolation, fails to fully thermalize to the temperature of the metal film heating it. A population of phonons exists which is emitted by the metal film, partially thermalizes the dielectric and is then reabsorbed in the metal film without escaping from the device structure to the thermal bath. The size of this population and its contribution to the heat capacity are estimated for several device scenarios

The intellectual and moral integrity of bioethics: response to commentaries on A case study in unethical transgressive bioethics: \u27Letter of concern from bioethicists\u27 about the prenatal administration of dexamethasone .

In our target article we showed that the Letter of Concern (LoC) fails to meet accepted standards for presenting empirical data for the purpose of supplementing a normative claim and for argument-based normative ethics. The LoC fails to meet the standards of evidence-based reasoning by making false claims, failing to reference data that undermine its key premises, and misrepresenting and misinterpreting the scientific publications it selectively references. The LoC fails to meet the standards of argument-based reasoning by treating as settled matters what are, instead, ongoing controversies, offering “mere opinion” as a substitute for argument, and making contradictory claims. The LoC is methodologically defective and thus a case study in unethical transgressive bioethics. Not withdrawing the LoC will damage the field of bioethics, making this case study in unethical transgressive bioethics important for the entire field

Electron Quasiparticles Drive the Superconductor-to-Insulator Transition in Homogeneously Disordered Thin Films

Transport data on Bi, MoGe, and PbBi/Ge homogeneously-disordered thin films demonstrate that the critical resistivity, $R_c$, at the nominal insulator-superconductor transition is linearly proportional to the normal sheet resistance, $R_N$. In addition, the critical magnetic field scales linearly with the superconducting energy gap and is well-approximated by $H_{c2}$. Because $R_N$ is determined at high temperatures and $H_{c2}$ is the pair-breaking field, the two immediate consequences are: 1) electron-quasiparticles populate the insulating side of the transition and 2) standard phase-only models are incapable of describing the destruction of the superconducting state. As gapless electronic excitations populate the insulating state, the universality class is no longer the 3D XY model. The lack of a unique critical resistance in homogeneously disordered films can be understood in this context. In light of the recent experiments which observe an intervening metallic state separating the insulator from the superconductor in homogeneously disordered MoGe thin films, we argue that the two transitions that accompany the destruction of superconductivity are 1) superconductor to Bose metal in which phase coherence is lost and 2) Bose metal to localized electron insulator via pair-breaking.Comment: This article is included in the Festschrift for Prof. Michael Pollak on occasion of his 75th birthda

Fluctuation Effects in High Sheet Resistance Superconducting Films

As the normal state sheet resistance, $R_n$, of a thin film superconductor increases, its superconducting properties degrade. For $R_n\simeq h/4e^2$ superconductivity disappears and a transition to a nonsuperconducting state occurs. We present electron tunneling and transport measurements on ultrathin, homogeneously disordered superconducting films in the vicinity of this transition. The data provide strong evidence that fluctuations in the amplitude of the superconducting order parameter dominate the tunneling density of states and the resistive transitions in this regime. We briefly discuss possible sources of these amplitude fluctuation effects. We also describe how the data suggest a novel picture of the superconductor to nonsuperconductor transition in homogeneous 2D systems.Comment: 11 pages, 5 figure

Professionally responsible counseling when a fetal anomaly is diagnosed by ultrasound

© The Author(s). 2020. Ethics plays an essential role in the clinical management of pregnancies complicated by fetal anomalies diagnosed by ultrasound. Utilizing the prima facie ethical principles of beneficence and respect for autonomy, this paper first explicates the ethical concept of the fetus as a patient. This ethical concept provides the basis for a comprehensive approach to counseling pregnant women about the management of pregnancies complicated by fetal anomalies. Practical, ethically justified guidance is given for counseling about decisions both before and after viabilities

A Big Data Architecture for Log Data Storage and Analysis

We propose an architecture for analysing database connection logs across different instances of databases within an intranet comprising over 10,000 users and associated devices. Our system uses Flume agents to send notifications to a Hadoop Distributed File System for long-term storage and ElasticSearch and Kibana for short-term visualisation, effectively creating a data lake for the extraction of log data. We adopt machine learning models with an ensemble of approaches to filter and process the indicators within the data and aim to predict anomalies or outliers using feature vectors built from this log data