Efficiency in sequential testing: Comparing the sequential probability ratio test and the sequential Bayes factor test

In a sequential hypothesis test, the analyst checks at multiple steps during data collection whether sufficient evidence has accrued to make a decision about the tested hypotheses. As soon as sufficient information has been obtained, data collection is terminated. Here, we compare two sequential hypothesis testing procedures that have recently been proposed for use in psychological research: Sequential Probability Ratio Test (SPRT; Psychological Methods, 25(2), 206–226, 2020) and the Sequential Bayes Factor Test (SBFT; Psychological Methods, 22(2), 322–339, 2017). We show that although the two methods have different philosophical roots, they share many similarities and can even be mathematically regarded as two instances of an overarching hypothesis testing framework. We demonstrate that the two methods use the same mechanisms for evidence monitoring and error control, and that differences in efficiency between the methods depend on the exact specification of the statistical models involved, as well as on the population truth. Our simulations indicate that when deciding on a sequential design within a unified sequential testing framework, researchers need to balance the needs of test efficiency, robustness against model misspecification, and appropriate uncertainty quantification. We provide guidance for navigating these design decisions based on individual preferences and simulation-based design analyses

Advances in tensiometer-based suction control systems.

Cunningham (2000) and Jotisankasa (2005) pioneered the development of tensiometer-based suction control systems. In these systems, wetting and drying of the soil are achieved by water injection and circulation of air in contact with the specimen while suction is monitored by sample-mounted high suction tensiometers. Unlike the axis translation technique, these systems avoid using elevated air pressures and better reproduce the drying and wetting conditions occurring in the field. Building upon these earlier works, this pa-per describes an automated tensiometer-based suction control system that enables direct measurement of water content changes inside the sample. A diaphragm pump forces air to flow inside a closed loop that runs across the sample while a moisture trap ensures that the relative humidity of the circulating air is kept low. As the circulating air dries the soil, the amount of abstracted water is measured by continuous weighing of the desiccant inside the moisture trap. Wetting of the sample is instead achieved by controlled injection of water through a solenoid valve connected to a pressurized volume gauge. The changes of soil water content are given by the difference between the amounts of water injected by the volume gauge and that retained by the desiccant. The system is used to impose cycles of drying and wetting on compacted clayey specimens and results from preliminary tests are presented

A lattice model for the kinetics of rupture of fluid bilayer membranes

We have constructed a model for the kinetics of rupture of membranes under tension, applying physical principles relevant to lipid bilayers held together by hydrophobic interactions. The membrane is characterized by the bulk compressibility (for expansion), the thickness of the hydrophobic part of the bilayer, the hydrophobicity and a parameter characterizing the tail rigidity of the lipids. The model is a lattice model which incorporates strain relaxation, and considers the nucleation of pores at constant area, constant temperature, and constant particle number. The particle number is conserved by allowing multiple occupancy of the sites. An equilibrium ``phase diagram'' is constructed as a function of temperature and strain with the total pore surface and distribution as the order parameters. A first order rupture line is found with increasing tension, and a continuous increase in proto-pore concentration with rising temperature till instability. The model explains current results on saturated and unsaturated PC lipid bilayers and thicker artificial bilayers made of diblock copolymers. Pore size distributions are presented for various values of area expansion and temperature, and the fractal dimension of the pore edge is evaluated.Comment: 15 pages, 8 figure

In-pandemic development of an application ontology for COVID-19 surveillance in a primary care sentinel network

Background: Creating an ontology for coronavirus disease 2019 (COVID-19) surveillance should help ensure transparency and consistency. Ontologies formalise conceptualisations at either domain or application level. Application ontologies cross domains and are specified through testable use cases. Our use case was extension of the role of the Oxford Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) to monitor the current pandemic and become an in-pandemic research platform. Objective: To develop an application ontology for COVID-19 which can be deployed across the various use case domains of the Oxford- RCGP RSC research and surveillance activities. Methods: We described our domain-specific use case. The actor was the RCGP RSC sentinel network; the system the course of the COVID-19 pandemic; the outcomes the spread and effect of mitigation measures. We used our established three-step method to develop the ontology, separating ontological concept development from code mapping and data extract validation. We developed a coding system–independent COVID-19 case identification algorithm. As there were no gold standard pandemic surveillance ontologies, we conducted a rapid Delphi consensus exercise through the International Medical Informatics Association (IMIA) Primary Health Care Informatics working group and extended networks. Results: Our use case domains included primary care, public health, virology, clinical research and clinical informatics. Our ontology supported: (1) Case identification, microbiological sampling and health outcomes at both an individual practice and national level; (2) Feedback through a dashboard; (3) A national observatory, (4) Regular updates for Public Health England, and (5) Transformation of the sentinel network to be a trial platform. We have identified a total of 8,627 people with a definite COVID-19 status, 4,240 with probable, and 59,147 people with possible COVID-19, within the RCGP RSC network (N=5,056,075). Conclusions: The underpinning structure of our ontological approach has coped with multiple clinical coding challenges. At a time when there is uncertainty about international comparisons, clarity about the basis on which case definitions and outcomes are made from routine data is essential

Response of plastic scintillator detectors to heavy ions, Z E <= 170 MeV

The fluorescent response, L, of plastic scintillators such as NE102 has been measured for a variety of heavy ions, Z = 1-35, at near-normal incidence with energies ranging from a few MeV to over a hundred MeV. The response in general is non-linear with L [is proportial to] f(Z, A)E1.6 in the region E/A R, with L [is proportial to] Z1.22 (R-0.04 Z), where R is in mg/cm2. Such an expression also appears to describe the response of other scintillators, such as NaI(Tl), for heavy ions. Scintillation efficiency, dL/dE, and specific fluorescence, dL/dx, have been deduced from the plastic scintillator data. These quantities do not appear to be simple functions of the ion energy loss, dE/dx. The results can be described using simple models which include the effects of secondary electrons, however.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/21662/1/0000049.pd

The differential diagnosis of chronic daily headaches: an algorithm-based approach

Chronic daily headaches (CDHs) refers to primary headaches that happen on at least 15 days per month, for 4 or more hours per day, for at least three consecutive months. The differential diagnosis of CDHs is challenging and should proceed in an orderly fashion. The approach begins with a search for “red flags” that suggest the possibility of a secondary headache. If secondary headaches that mimic CDHs are excluded, either on clinical grounds or through investigation, the next step is to classify the headaches based on the duration of attacks. If the attacks last less than 4 hours per day, a trigeminal autonomic cephalalgia (TAC) is likely. TACs include episodic and chronic cluster headache, episodic and chronic paroxysmal hemicrania, SUNCT, and hypnic headache. If the duration is ≥4 h, a CDH is likely and the differential diagnosis encompasses chronic migraine, chronic tension-type headache, new daily persistent headache and hemicrania continua. The clinical approach to diagnosing CDH is the scope of this review