Initial impacts of the transformation of a large introductory lab course focused on developing experimental skills and expert epistemology

Recently, there has been increased attention to improving laboratory instruction at all levels. At the introductory level, research results have shown differing levels of success based on the nature of the desired learning outcomes. In response to these findings, the University of Colorado's introductory physics lab course was transformed to improve students' development of experimental skills and experimental physics epistemology. We describe the details of the transformation process and initial self-reported learning gains from the first implementation of the transformed course

Hairy Black Holes, Horizon Mass and Solitons

Properties of the horizon mass of hairy black holes are discussed with emphasis on certain subtle and initially unexpected features. A key property suggests that hairy black holes may be regarded as `bound states' of ordinary black holes without hair and colored solitons. This model is then used to predict the qualitative behavior of the horizon properties of hairy black holes, to provide a physical `explanation' of their instability and to put qualitative constraints on the end point configurations that result from this instability. The available numerical calculations support these predictions. Furthermore, the physical arguments are robust and should be applicable also in more complicated situations where detailed numerical work is yet to be carried out.Comment: 25 pages, 5 (new) figures. Revtex file. Final version to appear in CQ

Effects of Varying Gravity Levels on fNIRS Headgear Performance and Signal Recovery

This paper reviews the effects of varying gravitational levels on functional Near-Infrared Spectroscopy (fNIRS) headgear. The fNIRS systems quantify neural activations in the cortex by measuring hemoglobin concentration changes via optical intensity. Such activation measurement allows for the detection of cognitive state, which can be important for emotional stability, human performance and vigilance optimization, and the detection of hazardous operator state. The technique depends on coupling between the fNIRS probe and users skin. Such coupling may be highly susceptible to motion if probe-containing headgear designs are not adequately tested. The lack of reliable and self-applicable headgear robust to the influence of motion artifact currently inhibits its operational use in aerospace environments. Both NASAs Aviation Safety and Human Research Programs are interested in this technology as a method of monitoring cognitive state of pilots and crew

Einstein-Yang-Mills Isolated Horizons: Phase Space, Mechanics, Hair and Conjectures

The concept of "Isolated Horizon" has been recently used to provide a full Hamiltonian treatment of black holes. It has been applied successfully to the cases of {\it non-rotating}, {\it non-distorted} black holes in Einstein Vacuum, Einstein-Maxwell and Einstein-Maxwell-Dilaton Theories. In this note, it is investigated the extent to which the framework can be generalized to the case of non-Abelian gauge theories where `hairy black holes' are known to exist. It is found that this extension is indeed possible, despite the fact that in general, there is no `canonical normalization' yielding a preferred Horizon Mass. In particular the zeroth and first laws are established for all normalizations. Colored static spherically symmetric black hole solutions to the Einstein-Yang-Mills equations are considered from this perspective. A canonical formula for the Horizon Mass of such black holes is found. This analysis is used to obtain nontrivial relations between the masses of the colored black holes and the regular solitonic solutions in Einstein-Yang-Mills theory. A general testing bed for the instability of hairy black holes in general non-linear theories is suggested. As an example, the embedded Abelian magnetic solutions are considered. It is shown that, within this framework, the total energy is also positive and thus, the solutions are potentially unstable. Finally, it is discussed which elements would be needed to place the Isolated Horizons framework for Einstein-Yang-Mills theory in the same footing as the previously analyzed cases. Motivated by these considerations and using the fact that the Isolated Horizons framework seems to be the appropriate language to state uniqueness and completeness conjectures for the EYM equations --in terms of the horizon charges--, two such conjectures are put forward.Comment: 24 pages, 3 figures, Revtex fil

Non-minimally coupled scalar fields and isolated horizons

The isolated horizon framework is extended to include non-minimally coupled scalar fields. As expected from the analysis based on Killing horizons, entropy is no longer given just by (a quarter of) the horizon area but also depends on the scalar field. In a subsequent paper these results will serve as a point of departure for a statistical mechanical derivation of entropy using quantum geometry.Comment: 14 pages, 1 figure, revtex4. References and minor clarifications adde

Structural basis for chain release from the enacyloxin polyketide synthase

Modular polyketide synthases and nonribosomal peptide synthetases are molecular assembly lines consisting of several multienzyme subunits that undergo dynamic self-assembly to form a functional mega-complex. N- and C-terminal docking domains are usually responsible for mediating interactions between subunits. Here we show that communication between two nonribosomal peptide synthetase subunits responsible for chain release from the enacyloxin polyketide synthase, which assembles an antibiotic with promising activity against Acinetobacter baumannii, is mediated by an intrinsically disordered short linear motif and a ß-hairpin docking domain. The structures, interactions and dynamics of these subunits are characterised using several complementary biophysical techniques, providing extensive insights into binding and catalysis. Bioinformatics analyses reveal that short linear motif/ß-hairpin docking domain pairs mediate subunit interactions in numerous nonribosomal peptide and hybrid polyketide-nonribosomal peptide synthetases, including those responsible for assembling several important drugs. Short linear motifs and ß-hairpin docking domains from heterologous systems are shown to interact productively, highlighting the potential of such interfaces as tools for biosynthetic engineering

Lower-order ODEs to determine new twisting type N Einstein spaces via CR geometry

In the search for vacuum solutions, with or without a cosmological constant, of the Einstein field equations of Petrov type N with twisting principal null directions, the CR structures to describe the parameter space for a congruence of such null vectors provide a very useful tool. A work of Hill, Lewandowski and Nurowski has given a good foundation for this, reducing the field equations to a set of differential equations for two functions, one real, one complex, of three variables. Under the assumption of the existence of one Killing vector, the (infinite-dimensional) classical symmetries of those equations are determined and group-invariant solutions are considered. This results in a single ODE of the third order which may easily be reduced to one of the second order. A one-parameter class of power series solutions, g(w), of this second-order equation is realized, holomorphic in a neighborhood of the origin and behaving asymptotically as a simple quadratic function plus lower-order terms for large values of w, which constitutes new solutions of the twisting type N problem. The solution found by Leroy, and also by Nurowski, is shown to be a special case in this class. Cartan's method for determining equivalence of CR manifolds is used to show that this class is indeed much more general. In addition, for a special choice of a parameter, this ODE may be integrated once, to provide a first-order Abel equation. It can also determine new solutions to the field equations although no general solution has yet been found for it.Comment: 28 page

APOBEC3 deaminase editing in mpox virus as evidence for sustained human transmission since at least 2016

Historically, mpox has been characterized as an endemic zoonotic disease that transmits through contact with the reservoir rodent host in West and Central Africa. However, in May 2022, human cases of mpox were detected spreading internationally beyond countries with known endemic reservoirs. When the first cases from 2022 were sequenced, they shared 42 nucleotide differences from the closest mpox virus (MPXV) previously sampled. Nearly all these mutations are characteristic of the action of APOBEC3 deaminases, host enzymes with antiviral function. Assuming APOBEC3 editing is characteristic of human MPXV infection, we developed a dual-process phylogenetic molecular clock that-inferring a rate of ~6 APOBEC3 mutations per year-estimates that MPXV has been circulating in humans since 2016. These observations of sustained MPXV transmission present a fundamental shift to the perceived paradigm of MPXV epidemiology as a zoonosis and highlight the need for revising public health messaging around MPXV as well as outbreak management and control.Editor’s summary: In March 2022, an international epidemic of human Mpox was detected, showing that it was not solely a zoonotic infection. A hallmark of the approximately 88,000 cases that have been reported were TC>TT and GA>AA mutations in Mpox viruses, which were acquired at a surprisingly high evolutionary rate for a pox virus. Knowing that these types of mutation are a sign of activity by a host antiviral enzyme called APOBEC3, O’Toole et al. investigated whether the mutations reflected human-to-human transmission rather than repeated zoonotic spillover. Bayesian evolutionary analysis showed that Mpox virus recently diversified into several lineages in humans that display elevated numbers of mutations, signaling APOBEC exposure and sustained human-to-human transmission rather than zoonosis as the source of new cases. —Caroline AshWellcome Trust ARTIC (Collaborators Award 206298/Z/17/Z, ARTIC network) (Á.O.T., P.L., M.A.S., A.R.); European Research Council (grant agreement no. 725422 – ReservoirDOCS) (P.L., M.A.S., A.R.); National Institutes of Health (R01 AI153044) (P.L., M.A.S., A.R.); David and Lucile Packard Foundation (M.W.); Research Foundation, Flanders– Fonds voor Wetenschappelijk Onderzoek–Vlaanderen, G066215N, G0D5117N and G0B9317N (P.L.); HORIZON 2020 EU grant 874850 MOOD (P.L.); HERA project (grant/2021/PHF/23776) supported by the European Commission through the European Centre for Disease Control and Prevention (V.B. and J.P.G.). The Nigeria Centre for Disease Control and Prevention receives core funding from the Nigerian government.info:eu-repo/semantics/publishedVersio