bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-time dynamics of the Dirac-Fock-Podolsky model of QED
Authors: Deckert Dirk-André , Nickel Lukas
Published: July 2019

Dirac, Fock, and Podolsky devised a relativistic model in 1932 in which a fixed number of N Dirac electrons interact through a second-quantized electromagnetic field. It is formulated with the help of a multitime wave function ψ(t1,x1,…,tN,xN) that generalizes the Schrödinger multiparticle wave function to allow for a manifestly relativistic formulation of wave mechanics. The dynamics is given in terms of N evolution equations that have to be solved simultaneously. Integrability imposes a rather strict constraint on the possible forms of interaction between the N particles and makes the rigorous construction of interacting dynamics a long-standing problem, also present in the modern formulation of quantum field theory. For a simplified version of the multitime model, in our case describing N Dirac electrons that interact through a relativistic scalar field, we prove well-posedness of the corresponding multitime initial value problem and discuss the mechanism and type of interaction between the charges. For the sake of mathematical rigor, we are forced to employ an ultraviolet cutoff in the scalar field. Although this again breaks the desired relativistic invariance, this violation occurs only on the arbitrarily small but finite length-scale of this cutoff. In view of recent progress in this field, the main mathematical challenges faced in this work are, on the one hand, the unboundedness from below of the free Dirac Hamiltonians and the unbounded, time-dependent interaction terms, and on the other hand, the necessity of pointwise control of the multitime wave function.
Analysis of vortices formed in flow passage of a five-bladed centrifugal water pump by means of PIV method
Authors: Wang Yanping , Yang Hui , Chen Bo , Gao Panlong , Chen Hui , Zhu Zuchao
Published: July 2019

Detailed optical measurements for the flow inside rotating passages of a five-bladed centrifugal impeller were performed by particle image velocimetry (PIV). The flow in mid-plane perpendicular to the pump axis was measured at 1400 r/min rotation speed. Seven flow rates, namely, 1.2, 1.0, 0.8, 0.6, 0.4, 0.2, and 0 Qd, were surveyed. The averaged PIV velocity maps and streamline were analyzed. Results show that when flow rate decreases to 0.8 Qd, the flow separation forms initially at the blade suction side in passage 1. With decreasing of flow rate, the flow separation appears in much more passage, the separation region enlarges, and the flow at the pressure side begins to form flow separation. All passages are gradually occupied by the vortices generated by flow separation, until the passages are finally blocked. The scale of vortex along the stream-wise direction at the suction side is larger than that at the pressure side, whereas the scale of vortex along the span-wise direction is smaller than that at the pressure side. With the decrease in flow rate, the scales of vortices at the suction and pressure sides increase, and the vortices at both sides move toward the inlet and outlet, respectively. Moreover, the effect of vortices on the tangential and radial components of the absolute velocity was analyzed.
Structural periodicity in laser additive manufactured Zr-based bulk metallic glass
Authors: Best James P. , Evenson Zach , Yang Fan , Dippel Ann-Christin , Stolpe Moritz , Gutowski Olof , Hasib M. Tarik , Li Xiaopeng , Kruzic Jamie J.
Published: July 2019

Additive manufacturing of bulk metallic glasses (BMGs) allows for effective bypassing of critical casting thickness constraints for glassy alloys, opening up this exciting material class to new applications. An open question is how the laser processing of such materials affects the short-range structural order, a critical mediating parameter for glass deformation. Synchrotron X-ray microdiffraction was used to understand structural heterogeneity across the build-planes of a selective laser melted Zr-based BMG. While negligible macroscopic heterogeneity in the structure was observed over a 10 mm build height for the X-ray amorphous material, small periodic variations were observed on the order of 40–80 μm. This dimensional scale was rationalized as a consequence of melt-pool solidification from laser processing, which imparts a calculated local strain variation of ±0.1%. It is anticipated that this structural insight will help to rationalize microscale deformation effects from the periodic structural variation of selective laser melting produced BMGs.
In situ monitoring of electric field effect on domain wall motion in Co ultrathin films in direct contact with an electrolyte
Authors: Lamirand A. D. , Adam J.-P. , Ravelosona D. , Allongue P. , Maroun F.
Published: July 2019

We present experimental data on the electric field effect on the magnetic domain wall dynamics in Co ultrathin films in direct contact with an aqueous electrolyte and in the absence of any oxide layer. We use a three electrode electrochemical setup to apply a large and uniform electric field and to precisely separate chemical effects induced by hydrogen from pure electric field effects. We show that in the case of the pure electric field effect, the domain wall velocity varies exponentially with the electric field and that these variations are larger than those observed previously on similar systems due to a larger magnetoelectric coefficient in our case.
Direct loading of nanoparticles under high vacuum into a Paul trap for levitodynamical experiments
Authors: Bykov Dmitry S. , Mestres Pau , Dania Lorenzo , Schmöger Lisa , Northup Tracy E.
Published: July 2019

Mechanical oscillators based on levitated particles are promising candidates for sensitive detectors and platforms for testing fundamental physics. The targeted quality factors for such oscillators correspond to extremely low damping rates of the center-of-mass motion, which can only be obtained if the particles are trapped in ultrahigh vacuum (UHV). In order to reach such low pressures, a noncontaminating method of loading particles in a UHV environment is necessary. However, loading particle traps at pressures below the viscous flow regime is challenging due to the conservative nature of trapping forces and reduced gas damping. We demonstrate a technique that allows us to overcome these limitations and load particles into a Paul trap at pressures as low as 4 × 10–7 mbar. The method is based on laser-induced acoustic desorption of nanoparticles from a metallic foil and temporal control of the Paul trap potential. We show that the method is highly efficient: More than half of the trapping attempts are successful. Moreover, since trapping attempts can be as short as a few milliseconds, the technique provides high throughput of loaded particles. Finally, the efficiency of the method does not depend on pressure, indicating that the method should be extensible to UHV.
Thermal conductivity variation of Bi2Te3 nanofilm with interfacial defects using molecular dynamics
Authors: Lai Tang-Yu , Fang Te-Hua , Huang Chao-Chun
Published: July 2019

In this study, the thermal conductivity and thermal boundary resistance (TBR) of Bi2Te3 nanofilms with different interfacial defects were investigated using nonequilibrium molecular dynamics simulations, and the effects of temperature, defects (step junctions and grooves), and interfaces (amorphous and telluride) were assessed. The results show a strong temperature dependence of the thermal conductivity for Bi2Te3 nanofilms with an ideal structure; moreover, as the height of step-junction defects increased, the thermal conductivity decreased, exhibiting a linear dependency. In addition, the thermal conductivity gradually decreased by 36%–40% as the width of the interface defects increased. We also verified the self-assembly mechanism for nanoscale Bi2Te3 and found that the Bi2Te3–Te interface induces strong phonon scattering. In addition, the TBR decreased as the width of the amorphous or Te interface increased. Thus, interfacial defects in Bi2Te3 nanofilms affect the thermal conductivity and TBR. The results of this study may be useful for optimizing Bi2Te3 thermoelectric devices in the future.
Correlated Brownian motion and diffusion of defects in spatially extended chaotic systems
Authors: da Silva S. T. , Prado T. L. , Lopes S. R. , Viana R. L.
Published: July 2019

One of the spatiotemporal patterns exhibited by coupled map lattices with nearest-neighbor coupling is the appearance of chaotic defects, which are spatially localized regions of chaotic dynamics with a particlelike behavior. Chaotic defects display random behavior and diffuse along the lattice with a Gaussian signature. In this note, we investigate some dynamical properties of chaotic defects in a lattice of coupled chaotic quadratic maps. Using a recurrence-based diagnostic, we found that the motion of chaotic defects is well-represented by a stochastic time series with a power-law spectrum 1/fσ with 2.3≤σ≤2.4, i.e., a correlated Brownian motion. The correlation exponent corresponds to a memory effect in the Brownian motion and increases with a system parameter as the diffusion coefficient of chaotic defects.
Porifera (Calcarea: Lithonida) from the Lower Miocene Batesford Limestone, Victoria, Australia, including a new species Monoplectroninia malonei sp. nov.
Authors: McSweeney Fearghus , Buckeridge John , Kelly Michelle
Published: July 2019

An exceptional fauna of calcareous sponges (Porifera: Calcarea) from the lowest biofacies of the Batesford Limestone (Lower Miocene), exposed in the Australian Portland Cement Quarry, Fyansford, near Geelong, southern Victoria, is reviewed. Four species have been recognised from this biofacies by the authors: Tretocalia pezica Hinde, 1900, Bactronella australis Hinde, 1900, Plectroninia halli Hinde, 1900 and a new species, Monoplectroninia malonei sp. nov., described and named in this paper. The original descriptions of Hinde’s species have been expanded to include a more comprehensive description of ontogeny.
Maryborough, a new H5 meteorite find from Victoria, Australia
Authors: Birch William D. , Henry Dermot A. , Tomkins Andrew G.
Published: July 2019

The Maryborough meteorite is a new H5 ordinary chondrite discovered about 2 km south of Maryborough, Victoria, in May 2015. It is a single stone measuring approximately 39 × 14 × 14 cm and with a mass of 17 kg. Plentiful indistinct chondrules are up to 1 mm across in a strongly recrystallised plagioclase-bearing matrix. Olivine and orthopyroxene in both the matrix and chondrules are uniform in composition (Fo80.1Fa19.3Te0.5Ca-ol0.04 and En81.5Fs17.1Wo1.5 respectively).The main metallic phases present are kamacite, taenite and tetrataenite, often forming composite grains with troilite. There is no evidence for any shock-inducing event and the meteorite shows incipient weathering in the form of thin iron-oxide mantles around the Fe–Ni grains. A terrestrial age of less than 1000 years is estimated from C14 dating. While there are a number of historic reported meteor sightings in the Maryborough district, none can be tied to the meteorite’s find site. To date, Maryborough is the third H5 ordinary chondrite and the second largest single chondritic mass, after Kulnine (55 kg), found in Victoria.
Indigenous use of stellar scintillation to predict weather and seasonal change
Authors: Hamacher Duane W. , Barsa John , Passi Segar , Tapim Alo
Published: July 2019

Indigenous peoples across the world observe the motions and positions of stars to develop seasonal calendars. Changing properties of stars, such as their brightness and colour, are also used for predicting weather. Combining archival studies with ethnographic fieldwork in Australia’s Torres Strait, we explore the various ways Indigenous peoples utilise stellar scintillation (twinkling) as an indicator for predicting weather and seasonal change, and examine the Indigenous and Western scientific underpinnings of this knowledge. By observing subtle changes in the ways the stars twinkle, Meriam people gauge changing trade winds, approaching wet weather and temperature changes. We then examine how the Northern Dene of Arctic North America utilise stellar scintillation to forecast weather.
Background gamma radiation and soil activity measurements in the northern Marshall Islands
Authors: Abella Maveric K. I. L. , Molina Monica Rouco , Nikolić-Hughes Ivana , Hughes Emlyn W. , Ruderman Malvin A.
Published: July 2019

Significance

From 1946 to 1958, the United States tested 67 nuclear weapons in the Marshall Islands, a remote constellation of atolls in the Pacific Ocean that was then a US trust territory. Two atolls, Bikini and Enewetak, were used as ground zero for the tests, which caused unprecedented environmental contamination and, for the indigenous peoples of the islands, long-term adverse health effects. In addition to the populations of Bikini and Enewetak, the people of Rongelap and Utirik were also affected by radioactive fallout from the largest nuclear test the United States has ever conducted, the Bravo test held March 1, 1954. This article presents a picture of current radiological conditions by examining external gamma radiation and soil radionuclide activity concentrations.
In situ measurement of cesium-137 contamination in fruits from the northern Marshall Islands
Authors: Topping Carlisle E. W. , Abella Maveric K. I. L. , Berkowitz Michael E. , Molina Monica Rouco , Nikolić-Hughes Ivana , Hughes Emlyn W. , Ruderman Malvin A.
Published: July 2019

Significance

The United States performed nuclear testing on Bikini and Enewetak Atolls in the northern Marshall Islands between 1946 and 1958. Fallout from the largest test Bravo, detonated in 1954, spread over a large area, exposing to radiation not only land and ocean but also Marshallese people living in neighboring atolls, including Rongelap and Utirik. Cesium-137, present in the fallout, has a half-life of approximately 30 y and is readily absorbed by food crops, thus representing a health hazard for island inhabitants. In situ measurements of cesium-137 content were made for fruits from 11 islands on four atolls. Contamination remains above limits set by international safety standards in some measured fruits, and several islands display contamination from this human-made radionuclide.
Spindle-shaped viruses infect marine ammonia-oxidizing thaumarchaea
Authors: Kim Jong-Geol , Kim So-Jeong , Cvirkaite-Krupovic Virginija , Yu Woon-Jong , Gwak Joo-Han , López-Pérez Mario , Rodriguez-Valera Francisco , Krupovic Mart , Cho Jang-Cheon , Rhee Sung-Keun
Published: July 2019

Ammonia-oxidizing archaea (AOA) from the phylum Thaumarchaeota are ubiquitous in marine ecosystems and play a prominent role in carbon and nitrogen cycling. Previous studies have suggested that, like all microbes, thaumarchaea are infected by viruses and that viral predation has a profound impact on thaumarchaeal functioning and mortality, thereby regulating global biogeochemical cycles. However, not a single virus capable of infecting thaumarchaea has been reported thus far. Here we describe the isolation and characterization of threeNitrosopumilusspindle-shaped viruses (NSVs) that infect AOA and are distinct from other known marine viruses. Although NSVs have a narrow host range, they efficiently infect autochthonousNitrosopumilusstrains and display high rates of adsorption to their host cells. The NSVs have linear double-stranded DNA genomes of ∼28 kb that do not display appreciable sequence similarity to genomes of other known archaeal or bacterial viruses and could be considered as representatives of a new virus family, the “Thaspiviridae.” Upon infection, NSV replication leads to inhibition of AOA growth, accompanied by severe reduction in the rate of ammonia oxidation and nitrite reduction. Nevertheless, unlike in the case of lytic bacteriophages, NSV propagation is not associated with detectable degradation of the host chromosome or a decrease in cell counts. The broad distribution of NSVs in AOA-dominated marine environments suggests that NSV predation might regulate the diversity and dynamics of AOA communities. Collectively, our results shed light on the diversity, evolution, and potential impact of the virosphere associated with ecologically important mesophilic archaea.
Precipitation behavior of high-Nb containing modified HR3C heat-resistant steels during isothermal aging
Authors: Bai Jiaming , Yuan Yong , Zhang Peng , Yan Jingbo , You Caiyin
Published: July 2019

The effect of Cr content on microstructural stability of the modified high-Nb content HR3C austenitic heat-resistant steel has been investigated during thermal aging at 700°C. It was observed that the σ phase precipitated in the 23.5Cr–18Ni–1.7Nb–0.04C–0.1N (wt.%) steel after aging treatment. However, the σ phase was not observed throughout the aging up to 5000 h as the Cr content was reduced from 23.5 to 21.5 wt-%. Experimental results showed that the yield strength of steel with 23.5 wt-% Cr at room temperature increased from 261 to 492 MPa after aging for 5000 h. The strengthening is closely related to the precipitation of σ phase at early stage of aging (500–2000 h). The influence of alloying elements on the formation of σ phase is discussed.
Speech Act Theory and the Multiple Aims of Science
Authors: Franco Paul L.
Published: July 2019

I draw on speech act theory to understand the speech acts appropriate to the multiple aims of scientific practice and the role of nonepistemic values in evaluating speech acts made relative to those aims. First, I consider work that distinguishes explanatory speech acts from descriptive speech acts within scientific practice. I then show how speech act theory provides a framework to make sense of explaining’s and describing’s distinct felicity conditions. Finally, I argue that if explaining aims to convey understanding to particular audiences rather than describe literally across contexts, then evaluating explanatory speech acts directed to nonscientists involves nonepistemic criteria.
Universality Reduced
Authors: Franklin Alexander
Published: July 2019

The universality of critical phenomena is best explained by appeal to the Renormalization Group (RG). Batterman and Morrison, among others, have claimed that this explanation is irreducible. I argue that the RG account is reducible but that the higher-level explanation ought not to be eliminated. I demonstrate that the key assumption on which the explanation relies—the scale invariance of critical systems—can be explained in lower-level terms. However, we should not replace the RG explanation with a bottom-up account; rather, we should acknowledge that the explanation appeals to dependencies that may be traced down to lower levels.
What Everyone Should Say about Symmetries (and How Humeans Get to Say It)
Authors: Hicks Michael Townsen
Published: July 2019

The laws of nature have an internal explanatory structure. This leads to interesting questions for metaphysicians of laws. What is the nature of this explanation? Marc Lange has recently argued in favor of metalaws: higher-order laws governing other laws, of which symmetry principles may be an example. Lange argues that his view, unlike its competitors, can make sense of the explanatory power of symmetries. I agree with Lange about the explanatory structure of laws but disagree with him about the nature of this explanation. I then present a Humean view that neatly captures the explanatory power of symmetry principles.
Vortical structures interaction
Authors: Gaifullin A M , Gadzhiev D A , Zhvick V V , Zoubtsov A V
Published: July 2019

As a rule, a fluid flow near solid bodies is corresponded by vortical structures generation. Mathematical methods for study of vortical flows depend on the vortical structures genesis and scale. Four problems connected with the extended vortical structures interaction with each other and with solid bodies are solved in this paper.
Conservation laws and the equivalence group
Authors: Megrabov A G
Published: July 2019

The paper generalizes differential conservation laws for the two-dimensional hydrodynamic Euler equations and their equivalent conservation laws for families of streamlines previously derived by the author. Three-dimensional analogues of these results, i.e., differential conservation laws for the three-dimensional hydrodynamic Euler equations, are presented. All conservation laws are divergent identities of the form divF= 0 and are found in two equivalent forms: in “mathematical-physical” form, where the vector fieldFis expressed in terms of quantities included in the Euler equations and their partial derivatives, and in geometric form. The second form represents conservation laws for families of streamlines where the vector fieldFunder the divergence sign is expressed in terms of the classical geometric characteristics of curves — their Frenet unit vectorsτ,ν, andβ(the unit tangent, principal normal, and binormal vectors), the first curvature k, and the second curvatureϰ. Special attention is paid to the geometric interpretation of the obtained conservation laws and their constituent expressions. Issues related to the equivalence group of the eikonal equation and other equations are discussed.

All results were obtained using the general vector and geometric formulas (differential conservation laws and other formulas), obtained by the author for families of arbitrary smooth curves, families of arbitrary smooth surfaces, and arbitrary smooth vector fields.
Translational prospects of untethered medical microrobots
Authors: Ceylan Hakan , Yasa Immihan C , Kilic Ugur , Hu Wenqi , Sitti Metin
Published: July 2019

Untethered mobile microrobots have the potential to transform medicine radically. Their small size and wireless mobility can enable access to and navigation in confined, small, hard-to-reach, and sensitive inner body sites, where they can provide new ways of minimally invasive interventions and targeted diagnosis and therapy down to the cellular length scales with high precision and repeatability. The exponential recent progress of the field at the preclinical level raises anticipations for their near-future clinical prospects. To pave the way for this transformation to happen, however, the formerly proposed microrobotic system designs need a comprehensive review by including essential aspects that a microrobot needs to function properly and safely in given in vivo conditions of a targeted medical problem. The present review provides a translational perspective on medical microrobotics research with an application-oriented, integrative design approach. The blueprint of a medical microrobot needs to take account of microrobot shape, material composition, manufacturing technique, permeation of biological barriers, deployment strategy, actuation and control methods, medical imaging modality, and the execution of the prescribed medical tasks altogether at the same time. The incorporation of functional information pertaining each such element to the physical design of the microrobot is highly dependent on the specific clinical application scenario. We discuss the complexity of the challenges ahead and the potential directions to overcome them. We also throw light on the potential regulatory aspects of medical microrobots toward their bench-to-bedside translation. Such a multifaceted undertaking entails multidisciplinary involvement of engineers, materials scientists, biologists and medical doctors, and bringing their focus on specific medical problems where microrobots could make a disruptive or radical impact.
Moufang Loops and Groups with Triality are Essentially the Same Thing
Authors: Hall J.
Published: July 2019

In 1925 Élie Cartan introduced the principal of triality specifically for the Lie groups of type

D
4

D_4

, and in 1935 Ruth Moufang initiated the study of Moufang loops. The observation of the title was made by Stephen Doro in 1978 who was in turn motivated by work of George Glauberman from 1968. Here we make the statement precise in a categorical context. In fact the most obvious categories of Moufang loops and groups with triality are not equivalent, hence the need for the word “essentially.”
Thick groups have trivial Floyd boundary
Authors: Levcovitz Ivan
Published: July 2019

We prove that thick groups (and more generally thick graphs) have trivial Floyd boundary. This shows that a wide class of finitely generated groups that are non-relatively hyperbolic have trivial Floyd boundary. In addition to giving new examples, our result provides a common proof and framework for many of the known results in the literature.
Free products with amalgamation over central 𝐶*-subalgebras
Authors: Courtney Kristin , Shulman Tatiana
Published: July 2019

Let

A
A

and

B
B

be

C

∗

\mathrm {C}^*

-algebras whose quotients are all RFD (residually finite dimensional), and let

C
C

be a central

C

∗

\mathrm {C}^*

-subalgebra in both

A
A

and

B
B

. We prove that the full amalgamated free product

A

∗
C

B

A*_C B

is then RFD. This generalizes Korchagin’s result that amalgamated free products of commutative

C

∗

\mathrm {C}^*

-algebras are RFD. When applied to the case of trivial amalgam, our methods recover the result of Exel and Loring for separable

C

∗

\mathrm {C}^*

-algebras. As corollaries to our theorem, we give sufficient conditions for amalgamated free products of maximally almost periodic (MAP) groups to have RFD

C

∗

\mathrm {C}^*

-algebras and hence to be MAP.
Increased weighting on prior knowledge in Lewy body-associated visual hallucinations
Authors: Zarkali Angeliki , Adams Rick A , Psarras Stamatios , Leyland Louise-Ann , Rees Geraint , Weil Rimona S
Published: July 2019

Hallucinations are a common and distressing feature of many psychiatric and neurodegenerative conditions. In Lewy body disease, visual hallucinations are a defining feature, associated with worse outcomes; yet their mechanisms remain unclear and treatment options are limited. Here, we show that hallucinations in Lewy body disease are associated with altered integration of top-down predictions with incoming sensory evidence, specifically with an increased relative weighting of prior knowledge. We tested 37 individuals with Lewy body disease, 17 habitual hallucinators and 20 without hallucinations, and 20 age-matched healthy individuals. We employed an image-based learning paradigm to test whether people with Lewy body disease and visual hallucinations show higher dependence on prior knowledge. We used two-tone images that are difficult to disambiguate without any prior information but generate a strong percept when information is provided. We measured discrimination sensitivity before and after this information was provided. We observed that in people with Lewy body disease who experience hallucinations, there was greater improvement in discrimination sensitivity after information was provided, compared to non-hallucinators and controls. This suggests that people with Lewy body disease and hallucinations place higher relative weighting on prior knowledge than those who do not hallucinate. Importantly, increased severity of visual hallucinations was associated with an increased effect of prior knowledge. Together these findings suggest that visual hallucinations in Lewy body disease are linked to a shift towards top-down influences on perception and away from sensory evidence, perhaps due to an increase in sensory noise. This provides important mechanistic insights to how hallucinations develop in Lewy body disease, with potential for revealing new therapeutic targets.
Blind Submission
Authors: Bahrainwala Lamiyah
Published: July 2019

Muslims in the West are under pressure to perform nationalism and hegemonic gender ideology to neutralize themselves as threats. This has triggered a series of “blindfolded hug” viral videos that show individual Muslim males standing blindfolded in a busy street asking for hugs from passersby who “agree” that they are not a danger to society. In this article, I examine 51 such videos and argue that the visual of a minority male made abject reifies state might while building an aesthetic of peacefulness that Western Muslims are compelled to demonstrate. Such an aesthetic relies on the rhetorics of disability, the affective circulation of hate, and the stripping off of oppositional gazing to be read legibly by White audiences.
Urine Tenofovir Concentrations Correlate With Plasma and Relate to Tenofovir Disoproxil Fumarate Adherence: A Randomized, Directly Observed Pharmacokinetic Trial (TARGET Study)
Authors: Drain Paul K , Kubiak Rachel W , Siriprakaisil Oraphan , Klinbuayaem Virat , Quame-Amaglo Justice , Sukrakanchana Pra-Ornsuda , Tanasri Suriyan , Punyati Pimpinun , Sirirungsi Wasna , Cressey Ratchada , Bacchetti Peter , Okochi Hideaki , Baeten Jared M , Gandhi Monica , Cressey Tim R
Published: July 2019

Background

Direct measurement of tenofovir (TFV) in urine could be an objective measure to monitor adherence to preexposure prophylaxis (PrEP) or TFV-based antiretroviral therapy (ART).

Methods

We conducted a 3-arm randomized, pharmacokinetic study of tenofovir disoproxil fumarate (TDF) 300 mg/emtricitabine (FTC) 200 mg among adults living with human immunodeficiency virus. Participants were randomized to receive controlled TDF/FTC dosing as (1) “perfect” adherence (daily); (2) “moderate” adherence (4 doses/week); or (3) “low” adherence (2 doses/week). We obtained trough spot urine and plasma samples during a 6-week directly observed therapy period and a 4-week washout period. TFV concentrations were compared between adherence arms using 1-way analysis of variance.

Results

Among 28 participants, the median age was 33 years and 16 (57%) were male. Correlation between TFV plasma and urine concentrations was strong (ρ = 0.78; P < .0001). Median (interquartile range) steady-state trough TFV concentrations (ng/mL) for perfect, moderate, and low TDF adherence were 41 (26–52), 16 (14–19), and 4 (3–5) in plasma; and 6480 (3940–14 300), 3405 (2210–5020), and 448 (228–675) in urine. Trough TFV concentrations at steady state were significantly different between the 3 adherence arms for plasma (P < .0001) and urine (P = .0002). Following drug cessation, TFV concentrations persisted longer in urine than plasma samples. Washout urine TFV concentrations and time to undetectable concentrations did not differ between the 3 randomized adherence groups.

Conclusions

Urine TFV concentrations can inform interpretation of novel point-of-care urine-based TFV assays to assess recent TDF adherence.

Clinical Trials Registration

NCT0301260.
Algorithm in the Diagnosis of Febrile Illness Using Pathogen-specific Rapid Diagnostic Tests
Authors: Pokharel Sunil , White Lisa J , Aguas Ricardo , Celhay Olivier , Pellé Karell G , Dittrich Sabine
Published: July 2019

Background

In the absence of proper guidelines and algorithms, available rapid diagnostic tests (RDTs) for common acute undifferentiated febrile illnesses are often used inappropriately.

Methods

Using prevalence data of 5 common febrile illnesses from India and Cambodia, and performance characteristics (sensitivity and specificity) of relevant pathogen-specific RDTs, we used a mathematical model to predict the probability of correct identification of each disease when diagnostic testing occurs either simultaneously or sequentially in various algorithms. We developed a web-based application of the model so as to visualize and compare output diagnostic algorithms when different disease prevalence and test performance characteristics are introduced.

Results

Diagnostic algorithms with appropriate sequential testing predicted correct identification of etiology in 74% and 89% of patients in India and Cambodia, respectively, compared with 46% and 49% with simultaneous testing. The optimally performing sequential diagnostic algorithms differed in India and Cambodia due to varying disease prevalence.

Conclusions

Simultaneous testing is not appropriate for the diagnosis of acute undifferentiated febrile illnesses with presently available tests, which should deter the unsupervised use of multiplex diagnostic tests. The implementation of adaptive algorithms can predict better diagnosis and add value to the available RDTs. The web application of the model can serve as a tool to identify the optimal diagnostic algorithm in different epidemiological settings, while taking into account the local epidemiological variables and accuracy of available tests.
Strong population structure and limited gene flow between Yellow-billed Ducks and Mallards in southern Africa
Authors: Brown Joshua I , Lavretsky Philip , Cumming Graeme S , Peters Jeffrey L
Published: July 2019

Secondary contact and hybridization between recently diverged taxa have been increasing due to anthropogenic changes to the environment. Determining whether secondary contact leads to gene flow between species is important for understanding both the evolutionary consequences of such events (i.e. genetic swamping, speciation reversal, hybrid speciation) and for establishing proper conservation measures. Mallards (Anas platyrhynchos), which natively have a Holarctic distribution, have been introduced nearly worldwide due to game-farm and domestic pet releases. Their expanding range has resulted in secondary contact and increased incidences of hybridization with many closely related Mallard-like ducks that comprise the Mallard complex. Here, we assay molecular diversity for 19 nuclear introns and the mitochondrial DNA for wild Mallards (n = 50) across their Holarctic range and Yellow-billed Ducks (n = 30–75; Anas undulata) from southern Africa to determine population genetic structure and test for evidence of Mallard introgression into Yellow-billed Ducks. While we found limited support for contemporary gene flow across nuclear markers, we provide evidence from mitochondrial DNA that best supports ancient gene flow between Yellow-billed Ducks and Mallards. Yellow-billed Ducks best fit a single population at nuclear markers but show some location-specific mtDNA structure that suggests recent founder or bottleneck events. Although we find that introgression from Mallards into Yellow-billed Duck is limited, Yellow-billed Duck populations should be monitored to determine if expanding feral Mallard populations in southern Africa are increasing introgression.
Maternal androgen excess induces cardiac hypertrophy and left ventricular dysfunction in female mice offspring
Authors: Manti Maria , Fornes Romina , Pironti Gianluigi , McCann Haworth Sarah , Zhengbing Zhuge , Benrick Anna , Carlström Mattias , Andersson Daniel , Stener-Victorin Elisabet
Published: July 2019

Aims

Polycystic ovary syndrome (PCOS) is a common endocrinopathy that is suggested to increase the risk for cardiovascular disease. How PCOS may lead to adverse cardiac outcomes is unclear and here we hypothesized that prenatal exposure to dihydrotestosterone (DHT) and/or maternal obesity in mice induce adverse metabolic and cardiac programming in female offspring that resemble the reproductive features of the syndrome.

Methods and results

The maternal obese PCOS phenotype was induced in mice by chronic high-fat–high-sucrose consumption together with prenatal DHT exposure. The prenatally androgenized (PNA) female offspring displayed cardiac hypertrophy during adulthood, an outcome that was not accompanied by aberrant metabolic profile. The expression of key genes involved in cardiac hypertrophy was up-regulated in the PNA offspring, with limited or no impact of maternal obesity. Furthermore, the activity of NADPH oxidase, a major source of reactive oxygen species in the cardiovascular system, was down-regulated in the PNA offspring heart. We next explored for early transcriptional changes in the heart of newly born PNA offspring, which could account for the long-lasting changes observed in adulthood. Neonatal PNA hearts displayed an up-regulation of transcription factors involved in cardiac hypertrophic remodelling and of the calcium-handling gene, Slc8a2. Finally, to determine the specific role of androgens in cardiovascular function, female mice were continuously exposed to DHT from pre-puberty to adulthood, with or without the antiandrogen flutamide. Continuous exposure to DHT led to adverse left ventricular remodelling, and increased vasocontractile responses, while treatment with flutamide partly alleviated these effects.

Conclusion

Taken together, our results indicate that intrauterine androgen exposure programmes long-lasting heart remodelling in female mouse offspring that is linked to left ventricular hypertrophy and highlight the potential risk of developing cardiac dysfunction in daughters of mothers with PCOS.
Delimiting the Neoproterozoic São Francisco Paleocontinental Block with P-wave traveltime tomography
Authors: Rocha Marcelo Peres , Azevedo Paulo Araújo de , Assumpção Marcelo , Pedrosa-Soares Antônio Carlos , Fuck Reinhardt , Von Huelsen Monica Giannoccaro
Published: July 2019

The São Francisco Paleocontinental Block (SFPB) represents part of the Congo-São Francisco Paleocontinent (CSFP), amalgamated around 2 Ga. In the Neoproterozoic, a branched continental rift system evolved to ocean basins around most edges of the SFPB that remained only partially linked to the Congo Paleocontinent by means of the Bahia-Gabon Continental Bridge. After the Brasiliano—Pan-African orogeny, two relatively preserved CSFP sectors formed the São Francisco and Congo cratons, surrounded by Neoproterozoic orogenic belts. Recent results of upper mantle P-wave seismic tomography allowed us to suggest a delimitation in lithospheric depths of the Neoproterozoic SFPB, which comprise the São Francisco Craton, and that this would have been connected with the Congo Paleocontinent along the Araçuaí Belt. It is characterized by high-velocity anomalies and its boundaries with other blocks are marked by low-velocity anomalies at lithospheric depths. We tested the resolution of the tomographic results through synthetic models obtained by a ray tracing scheme using the observed ray configuration. We observe that the lateral resolution is adequate, but the method used was not able to set the depth reached by the SFPB. Our results indicate that the SFPB area in lithospheric depths is larger than the surface area ascribed to the São Francisco craton, and thus, the SFPB basement deeply extends beneath neighboring orogenic regions, suggesting that these Neoproterozoic mobile belts, such as Araçuaí Orogen and the Brasilia Fold Belt, reworked the continental crust. We observe a low-velocity anomaly in the SFPB central region, corresponding to the Pirapora aulacogen. Our results have a good spatial correspondence with the low Bouguer anomalies used to define the SFPB in previous studies. The limits of the SFPB are consistent with deviation of the mantle flow, as suggested by SKS fast polarization.
Homogenization of fault frictional properties
Authors: Ray Sohom , Viesca Robert C
Published: July 2019

The frictional properties of large faults are expected to vary in space. However, fault models often assume that properties are homogeneous, or nearly so. We investigate the conditions under which the details of variations may be neglected and properties homogenized. We do so by examining the behaviour of nonlinear solutions for unstably accelerating fault slip under frictional heterogeneity. We consider a rate- and state-dependent fault friction in which the characteristic wavelength for the property variations is a problem parameter. We find that homogenization is permissible only when that wavelength shows scale separation from an elasto-frictional length scale. However, fault models also often include property transitions that occur over distances comparable to the elasto-frictional length. We show that under such comparable variations, the dynamics of earthquake-nucleating instabilities is controlled by the properties’ spatial distribution.
Fertility preservation: should we reconsider the terminology?
Authors: Grynberg Michaël , Sermondade Nathalie
Published: July 2019

The term ‘fertility preservation’ embraces techniques that are actually mostly based on gamete and gonadal tissue cryopreservation. While the efficiency of these techniques in terms of live births remains difficult to establish, it is remarkable that this ambiguous terminology is routinely used and seems currently well accepted. In order to limit false hopes about the real chances of truly preserving fertility, our medical community should discuss qualifying the term ‘fertility preservation’. ‘Gamete or gonadal tissue cryopreservation’ could appear as a more unambiguous and realistic term. However, it probably captures only a segment of a more global ‘fertility preservation’ process. Discussing how and when to use which terminology, and even finding a more realistic and unifying term, should be further explored.
Left anterior descending artery revascularization with the right internal thoracic artery T-graft: the ‘reverse composite’ configuration
Authors: Ag-Rejuan Yael , Pevni Dmitry , Nesher Nachum , Kramer Amir , Paz Yosef , Mohr Rephael , Malamud Dorel , Ben-Gal Yanai
Published: July 2019

OBJECTIVES

The use of bilateral internal thoracic artery graft for myocardial revascularization has improved the long-term survival and decreased the rate of repeat interventions in patients. A key technical factor for complete arterial revascularization is sufficient length of the internal thoracic artery (ITA) graft. The purpose of this study was to compare early and long-term outcomes of ‘standard composite’ grafting and ‘reverse composite’ grafting. In the former, the left ITA (LITA) is connected to the left anterior descending artery, and the right ITA is connected end-to-side to the LITA for revascularization of the left circumflex artery. In ‘reverse composite’ grafting, the LITA is connected to the left circumflex artery, and the right ITA is connected end-to-side to the LITA, for revascularization of the left anterior descending artery.

METHODS

We compared the outcomes of 1365 patients who underwent coronary artery bypass grafting in Tel-Aviv Sourasky Medical Centre, using bilateral ITA as standard composite versus ‘reverse composite’ grafts, between January 1996 and December 2011. A propensity score matching analysis compared 132 pairs of patients who underwent bilateral ITA by the 2 modes.

RESULTS

Twelve hundred and thirty patients underwent standard ‘composite’ grafts and 135 underwent ‘reverse composite’ grafts. Early mortality and early adverse effects did not differ significantly between the groups. After matching, the difference in late mortality between the groups was not statistically significant.

CONCLUSIONS

This study suggests that revascularization of the left anterior descending with the right ITA, arising from an in situ LITA, is safe and provides early outcomes and long-term survival that are not significantly different from those of the standard composite grafting technique. However, there was evidence of better survival in the standard composite group.
Response to Mark Bell's “Defending the Acquisition-Use Presumption in Assessing the Likelihood of Nuclear Terrorism”
Authors: McIntosh Christopher , Storey Ian
Published: July 2019

This is a response to Mark Bell's “Defending the Acquisition-Use Presumption” by the authors of the original article “Between Acquisition and Use: Assessing the Likelihood of Nuclear Terrorism.”
The pattern speed of the Milky Way bar from transverse velocities
Authors: Sanders Jason L , Smith Leigh , Evans N Wyn
Published: July 2019

We use the continuity equation to derive a method for measuring the pattern speed of the Milky Way’s bar/bulge from proper motion data. The method has minimal assumptions but requires complete coverage of the non-axisymmetric component in two of the three Galactic coordinates. We apply our method to the proper motion data from a combination of Gaia DR2 and VISTA Variables in the Via Lactea (VVV) to measure the pattern speed of the bar as $\Omega _\mathrm{p}=(41\pm 3)\, \mathrm{km\, s^{-1}\, kpc^{-1}}$ (where the error is statistical). This puts the corotation radius at $(5.7\pm 0.4)\, \mathrm{kpc}$, under the assumptions of the standard peculiar motion of the Sun and the absence of non-axisymmetric streaming in the Solar neighbourhood. The obtained result uses only data on the near side of the bar which produces consistent measurements of the distance and velocity of the centre of the Galaxy. Addition of the data on the far side of the bar pulls the pattern speed down to $\Omega _\mathrm{p}=(31\pm 1)\, \mathrm{km\, s^{-1}\, kpc^{-1}}$ but requires a lower transverse velocity for the Galactic centre than observed. This suggests systematics of $5-10\, \mathrm{km\, s^{-1}kpc^{-1}}$ dominate the uncertainty. We demonstrate using a dynamically formed bar/bulge simulation that even with the limited field of view of the VVV survey our method robustly recovers the pattern speed.
First Case Report of Human Bacteremia With Malacobacter (Arcobacter) mytili
Authors: Vasiljevic Marija , Fenwick Alexander J , Nematollahi Saman , Gundareddy Venkat P , Romagnoli Mark , Zenilman Jonathan , Carroll Karen C
Published: July 2019

Arcobacter spp. are commonly associated with shellfish and have been increasingly implicated in human gastrointestinal disease. We report the first case of human bacteremia with Malacobacter (previously Arcobacter) mytili acquired after exposure to Maryland crab. Arcobacter spp. should be considered in febrile illnesses when the history indicates exposure to seafood.
Effects of Intraoperative Magnetic Resonance Thermal Imaging Signal Artifact During Laser Interstitial Thermal Therapy on Thermal Damage Estimate and Postoperative Magnetic Resonance Imaging Ablative Area Concordance
Authors: Munier Sean M , Desai Akshay N , Patel Nitesh V , Danish Shabbar F
Published: July 2019

BACKGROUND

Magnetic resonance-guided laser interstitial thermal therapy (MRgLITT) is a minimally invasive procedure that utilizes intraoperative magnetic resonance thermal imaging (MRTI) to generate a thermal damage estimate (TDE) of the ablative area. In select cases, the MRTI contains a signal artifact or defect that distorts the ablative region. No study has considered the impact of this artifact on TDE accuracy.

OBJECTIVE

To determine the effect of intraoperative MRTI signal artifact on postoperative magnetic resonance imaging (MRI)-predicted ablative area.

METHODS

All ablations were performed using the Visualase MRI-Guided Laser Ablation System (Medtronic). Patients were grouped based on whether the intraoperative MRTI contained signal artifact that distorted the ablative region. Cross-sectional area of the ablative lesion from the MRI image was measured, and the difference between intraoperative TDE and postoperative MRI cross-sectional area was calculated and compared between groups with and without intraoperative MRTI artifact.

RESULTS

A total of 91 patients undergoing MRgLITT for various surgical indications were examined. MRTI artifact was observed in 43.9% of cases overall. The mean absolute difference between TDE and the postoperative MRI cross-sectional area was 94.8 mm2 (SEM = 11.6) in the group with intraoperative MRTI artifact and 54.4 mm2 (SEM = 5.5) in the nonartifact group.

CONCLUSION

MRTI signal artifact is common during LITT. The presence of signal artifact during intraoperative MRTI results in higher variation between intraoperative TDE and postoperative MRI cross-sectional ablative area. In cases in which intraoperative MRTI artifact is observed, there may be a larger degree of variation between observed intraoperative TDE and measured postoperative MRTI ablative area.