We determine approximate analytical solutions for average periodic trajectories of particles that are accelerated by the turbulent shearing of a fluid between collisions with a hydrodynamically rough ...bed. We indicate how the viscosity of the fluid may influence the collisions with the bed. The approximate solutions compare well with periodic solutions for average periodic trajectories over rigid bumpy and erodible beds that are generated numerically. The analytic solutions permit the determination of the relations between the particle flux and the strength of the shearing flow over a range of particle and fluid properties that vary between those for sand in air and sand in water.
ABSTRACT
Accurately measuring stellar parameters is a key goal to increase our understanding of the observable Universe. However, current methods are limited by many factors, in particular, the ...biases and physical assumptions that are the basis for the underlying evolutionary or atmospheric models, those that these methods rely upon. Here, we introduce our code spectrAl eneRgy dIstribution bAyesian moDel averagiNg fittEr (ariadne), which tackles this problem by using Bayesian Model Averaging to incorporate the information from all stellar models to arrive at accurate and precise values. This code uses spectral energy distribution fitting methods, combined with precise Gaia distances, to measure the temperature, log g, Fe/H, AV, and radius of a star. When compared with interferometrically measured radii ariadne produces values in excellent agreement across a wide range of stellar parameters, with a mean fractional difference of only 0.001 ± 0.070. We currently incorporate six different models, and in some cases we find significant offsets between them, reaching differences of up to 550 K and 0.6 R⊙ in temperature and radius, respectively. For example, such offsets in stellar radius would give rise to a difference in planetary radius of 60 per cent, negating homogeneity when combining results from different models. We also find a trend for stars smaller than 0.4–0.5 R⊙, which shows more work needs to be done to better model these stars, even though the overall extent is within the uncertainties of the interferometric measurements. We advocate for the use of ariadne to provide improved bulk parameters of nearby A to M dwarfs for future studies.
This paper discusses the findings of a small scale research project which explored the possibility of adopting eco-design techniques. The paper focuses on identifying how eco-design techniques can be ...determined as being compatible with new product development processes. Via the development of a five stage ‘applicability framework’, this study demonstrates how a compatible suite of tools can be identified for application to product development processes. Testing and validation of this ‘applicability framework’, which was used to identify three key eco-design techniques; namely checklists, guidelines, and a material, energy and toxicity (MET) matrix, is shown to have taken place in relation to the development of a lightweight chemical detector product. It is established that checklists, guidelines and the MET matrix can be used both on a specific product, and also more generally in the design process. In particular, the MET matrix is shown as being used to successfully identify key environmental aspects of the product during its lifetime. The paper concludes by arguing that eco-design techniques may not have been more widely adopted by businesses because such methods are not necessarily generic and immediately applicable, but instead require some form of process-specific customisation prior to use, which can in turn act as a barrier to adoption. It is also highlighted that the shear diversity of pressures that come to bear during the product development process can also act as a barrier to adoption, and that the full integration of eco-design techniques will have to encompass approaches which overcome such pressures.
Tissue-resident memory CD8+ T (Trm) cells share core residency gene programs with tumor-infiltrating lymphocytes (TILs). However, the transcriptional, metabolic, and epigenetic regulation of Trm cell ...and TIL development and function is largely undefined. Here, we found that the transcription factor Bhlhe40 was specifically required for Trm cell and TIL development and polyfunctionality. Local PD-1 signaling inhibited TIL Bhlhe40 expression, and Bhlhe40 was critical for TIL reinvigoration following anti-PD-L1 blockade. Mechanistically, Bhlhe40 sustained Trm cell and TIL mitochondrial fitness and a functional epigenetic state. Building on these findings, we identified an epigenetic and metabolic regimen that promoted Trm cell and TIL gene signatures associated with tissue residency and polyfunctionality. This regimen empowered the anti-tumor activity of CD8+ T cells and possessed therapeutic potential even at an advanced tumor stage in mouse models. Our results provide mechanistic insights into the local regulation of Trm cell and TIL function.
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•Bhlhe40 is required for Trm cell and TIL fitness and function•Bhlhe40 is critical for TIL reinvigoration following anti-PD-L1 blockade•Bhlhe40 programs Trm cell and TIL mitochondrial metabolism and active chromatin state•Epigenetic targeting Trm cell and TIL functional program promotes tumor control
The molecular regulation of CD8+ tissue-resident memory (Trm) cells and tumor-infiltrating lymphocytes (TILs) is incompletely understood. Li et al. report that the transcription factor Bhlhe40 was required for Trm cell and TIL mitochondrial fitness and epigenetic programming. They further identify an epigenetic regimen promoting TIL functional program for cancer immunotherapy.
We employ kinetic theory, extended to incorporate the influence of velocity correlations, friction and particle stiffness, and a model for rate-independent, elastic components of the stresses at ...volume fractions larger than a critical value, in an attempt to reproduce the results of discrete-element numerical simulations of steady, fully developed, dissipative, collisional shearing flows over and within inclined, erodible, fragile beds. The flows take place between vertical, frictional sidewalls at different separations with sufficient total particle flux so that differently inclined, erodible beds result. Numerical solutions of the spanwise-averaged differential equations of the theory and the associated boundary conditions are seen to be capable of reproducing profiles of stresses, solid volume fraction, average velocity and the strength of the particle velocity fluctuations, both in the rapid collisional flow above the bed and in the slower creeping flow within the bed. The indication is that extended kinetic theory has the unique ability to faithfully describe steady, inhomogeneous, granular shearing flows, ranging from dilute to extremely dense, using balances of momentum and energy and employing boundary conditions that are associated with the balances, with a small number of physically determined, microscopic parameters.
We extend models for granular flows based on the kinetic theory beyond the critical volume fraction at which a rate-independent contribution to the stresses develops. This involves the incorporation ...of a measure of the duration of the particle interaction before and after this volume fraction. At volume fractions less than the critical, the stress components contain contributions from momentum exchanged in collisions that are influenced by the particle elasticity. At volume fractions greater than the critical, the stress components contain both static contributions from particle elasticity and dynamic contributions from the momentum transfer associated with the release of elastic energy by the breaking of force chains. A simple expression for the duration of a collision before and after the critical volume fraction permits a smooth transition between the two regimes and predictions for the components of the stress in steady, homogeneous shearing that are in good agreement with the results of numerical simulations. Application of the theory to steady, inhomogeneous flows reproduces the features of such flows seen in numerical simulations and physical experiments.
We extend models for granular flows based on the kinetic theory beyond the critical volume fraction at which a rate-independent contribution to the stresses develops.
ABSTRACT
We determine rotation periods for 127 stars in the ∼115-Myr-old Blanco 1 open cluster using ∼200 d of photometric monitoring with the Next Generation Transit Survey. These stars span F5–M3 ...spectral types (1.2 M⊙ ≳ M ≳ 0.3 M⊙) and increase the number of known rotation periods in Blanco 1 by a factor of four. We determine rotation periods using three methods: Gaussian process (GP) regression, generalized autocorrelation function (G-ACF), and Lomb–Scargle (LS) periodogram, and find that the GP and G-ACF methods are more applicable to evolving spot modulation patterns. Between mid-F and mid-K spectral types, single stars follow a well-defined rotation sequence from ∼2 to 10 d, whereas stars in photometric multiple systems typically rotate faster. This may suggest that the presence of a moderate-to-high mass ratio companion inhibits angular momentum loss mechanisms during the early pre-main sequence, and this signature has not been erased at ∼100 Myr. The majority of mid-F to mid-K stars display evolving modulation patterns, whereas most M stars show stable modulation signals. This morphological change coincides with the shift from a well-defined rotation sequence (mid-F to mid-K stars) to a broad rotation period distribution (late-K and M stars). Finally, we compare our rotation results for Blanco 1 to the similarly aged Pleiades: the single-star populations in both clusters possess consistent rotation period distributions, which suggests that the angular momentum evolution of stars follows a well-defined pathway that is, at least for mid-F to mid-K stars, strongly imprinted by ∼100 Myr.
We consider plane, steady, homogeneous, rotational shearing flows of a granular gas of identical, inelastic, frictionless spheres. We introduce the balance equation for the second moment of the ...particle velocity fluctuations, solve it in an approximate way for shearing flows with arbitrary amounts of rotation, and determine the stress tensor based on these solutions. We consider the stress determined in this way in the context of Material Frame Indifference.
We consider the evolution of particle segregation in collisional flows of two types of spheres down rigid bumpy inclines in the absence of sidewalls. We restrict our analysis to dense flows and use ...an extension of kinetic theory to predict the concentration of the mixture and the profiles of mixture velocity and granular temperature. A kinetic theory for a binary mixture of nearly elastic spheres that do not differ by much in their size or mass is employed to predict the evolution of the concentration fractions of the two types of spheres. We treat situations in which the flow of the mixture is steady and uniform, but the segregation evolves, either in space or in time. Comparisons of the predictions with the results of discrete numerical simulation and with physical experiments are, in general, good.
Due to their higher planet–star mass ratios, M dwarfs are the easiest targets for detection of low-mass planets orbiting nearby stars using Doppler spectroscopy. Furthermore, because of their low ...masses and luminosities, Doppler measurements enable the detection of low-mass planets in their habitable zones that correspond to closer orbits than for solar-type stars. We re-analyse literature Ultraviolet and Visual Echelle Spectrograph (UVES) radial velocities of 41 nearby M dwarfs in a combination with new velocities obtained from publicly available spectra from the HARPS-ESO spectrograph of these stars in an attempt to constrain any low-amplitude Keplerian signals. We apply Bayesian signal detection criteria, together with posterior sampling techniques, in combination with noise models that take into account correlations in the data and obtain estimates for the number of planet candidates in the sample. More generally, we use the estimated detection probability function to calculate the occurrence rate of low-mass planets around nearby M dwarfs. We report eight new planet candidates in the sample (orbiting GJ 27.1, GJ 160.2, GJ 180, GJ 229, GJ 422, and GJ 682), including two new multiplanet systems, and confirm two previously known candidates in the GJ 433 system based on detections of Keplerian signals in the combined UVES and High Accuracy Radial velocity Planet Searcher (HARPS) radial velocity data that cannot be explained by periodic and/or quasi-periodic phenomena related to stellar activities. Finally, we use the estimated detection probability function to calculate the occurrence rate of low-mass planets around nearby M dwarfs. According to our results, M dwarfs are hosts to an abundance of low-mass planets and the occurrence rate of planets less massive than 10 M⊕ is of the order of one planet per star, possibly even greater. Our results also indicate that planets with masses between 3 and 10 M⊕ are common in the stellar habitable zones of M dwarfs with an estimated occurrence rate of 0.21
$^{+0.03}_{-0.05}$
planets per star.
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