ABSTRACT
We introduce the First Light And Reionisation Epoch Simulations (FLARES), a suite of zoom simulations using the EAGLE model. We resimulate a range of overdensities during the Epoch of ...Reionization (EoR) in order to build composite distribution functions, as well as explore the environmental dependence of galaxy formation and evolution during this critical period of galaxy assembly. The regions are selected from a large $(3.2 \, \mathrm{cGpc})^{3}$ parent volume, based on their overdensity within a sphere of radius 14 h−1 cMpc. We then resimulate with full hydrodynamics, and employ a novel weighting scheme that allows the construction of composite distribution functions that are representative of the full parent volume. This significantly extends the dynamic range compared to smaller volume periodic simulations. We present an analysis of the galaxy stellar mass function (GSMF), the star formation rate distribution function (SFRF), and the star-forming sequence (SFS) predicted by FLARES, and compare to a number of observational and model constraints. We also analyse the environmental dependence over an unprecedented range of overdensity. Both the GSMF and the SFRF exhibit a clear double-Schechter form, up to the highest redshifts (z = 10). We also find no environmental dependence of the SFS normalization. The increased dynamic range probed by FLARES will allow us to make predictions for a number of large area surveys that will probe the EoR in coming years, carried out on new observatories such as Roman and Euclid.
We introduce new specifications and estimation procedures of traditional distance functions that allow researchers to undertake environmental efficiency and productivity studies within a parametric ...stochastic framework. Relying on a translog distance function specification that treats the outputs' vector asymmetrically by allowing equiproportional desirable outputs expansion and undesirable outputs contraction, we discuss the relevant properties that characterize the environmental hyperbolic distance function, and show that it can be easily implemented using conventional econometric techniques based on maximum likelihood estimation. We illustrate our model estimating technical efficiency scores for a panel of U.S. electricity generating units that produce electricity and SO
2 emissions as byproduct.
This study investigates the Sub‐Auroral Polarization Streams (SAPS) and Sub‐Auroral Ion Drifts (SAID) along with the associated magnetospheric and ionospheric phenomena developed during 7–8 September ...2017. Then, a series of substorms occurred before and during the geomagnetic storm (SYM‐Hmin = −146 nT). Results are obtained by utilizing multi‐point observations. These show that during the pre‐storm period, when the ElectroMagnetic Ion‐Cyclotron waves resulted in drop‐out events, a series of sunward (westward) SAID‐in‐SAPS flows developed in the dusk‐midnight sector due to the small‐scale flow bursts reaching the SAPS channel and the westward SAPS flows were streaming antisunward after midnight. During the storm period, dawnside sunward (eastward) SAPS also developed, Kelvin‐Helmholtz (K‐H) vortices rolled along the magnetopause and the hot zone became structured by reflected K‐H waves near the plasmapause leading to auroral undulations (AUs). New findings include the correlation of AUs and K‐H waves in the structured hot zone implying that the Near‐Earth Plasma Sheet acted as a resonator after activation by the K‐H vortices on the magnetopause. Further evidence is provided by the dayside Equatorward Boundary Intensification and Poleward Moving Auroral Forms of which development was supported by the K‐H vortices on the magnetopause by carrying the magnetosheath plasma into the magnetosphere. Adding to previous studies, new results also include the correlated observations of storm‐enhanced density (SED) plume and poleward drifts underlying both the equatorward plasma bubbles and the higher latitude plasma density depletions, and thus verifying their poleward movement within the SED base and SED plume.
Key Points
Sunward Sub‐Auroral Ion Drifts‐in‐Sub‐Auroral Polarization Streams (SAPS) flows developed at dusk‐midnight and antisunward SAPS flows after midnight
Correlated auroral undulations and Kelvin‐Helmholtz waves (structuring the hot zone) suggest Near‐Earth Plasma Sheet resonator activation
Ram drifts depict the poleward drifts of plasma bubbles/depletions within the storm‐enhanced density base/plume
The emergence of passive galaxies in the early Universe results from the delicate interplay among the different physical processes responsible for their rapid assembly and the abrupt shut-down of ...their star formation activity. Investigating the individual properties and demographics of early passive galaxies improves our understanding of these mechanisms. In this work we present a follow-up analysis of the
z
> 3 passive galaxy candidates selected by Merlin et al. (2019, MNRAS, 490, 3309) in the CANDELS fields. We begin by first confirming the accuracy of their passive classification by exploiting their sub-millimetre emission to demonstrate the lack of ongoing star formation. Using archival ALMA observations we are able to confirm at least 61% of the observed candidates as passive. While the remainder lack sufficiently deep data for confirmation, we are able to validate the entire sample in a statistical sense. We then estimate the stellar mass function (SMF) of all 101 passive candidates in three redshift bins from
z
= 5 to
z
= 3. We adopt a stepwise approach that has the advantage of taking into account photometric errors, mass and selection completeness issues, as well as the Eddington bias, without any a posteriori correction. We observe a pronounced evolution in the SMF around
z
∼ 4, indicating that we are witnessing the emergence of the passive population at this epoch. Massive (
M
> 10
11
M
⊙
) passive galaxies, only accounting for a small (< 10%) fraction of galaxies at
z
> 4, become dominant at later epochs. Thanks to a combination of photometric quality, sample selection, and methodology, we overall find a higher density of passive galaxies than in previous works. The comparison with theoretical predictions, despite a qualitative agreement (at least for some of the models considered), denotes a still incomplete understanding of the physical processes responsible for the formation of these galaxies. Finally, we extrapolate our results to predict the number of early passive galaxies expected in surveys carried out with future facilities.
Conjugated aromatic macrocycles are attractive due to their unique photophysical and optoelectronic properties. In particular, the cyclic radially oriented π‐system of cycloparaphenylenes (CPPs) ...gives rise to photophysical properties unlike any other small molecule or carbon nanomaterial. CPPs have tunable emission, possess large extinction coefficients, wide effective Stokes shifts, and high quantum yields. However, accessing bright CPPs with emissions beyond 500 nm remains difficult. Herein, we present a novel and bright orange‐emitting CPP‐based fluorophore showing a dramatic 105 nm red‐shift in emission and striking 237 nm effective Stokes shift while retaining a large quantum yield of 0.59. We postulate, and experimentally and theoretically support, that the quantum yield remains large due to the lack of intramolecular charge transfer.
Moving towards the red: For the first time, the fluorescence of a cycloparaphenylene was dramatically red‐shifted without sacrificing quantum yield. This novel cycloparaphenylene has a strong absorption, high quantum yield and shows host–guest complexation with C60. Experimental and computational investigations explain its superior fluorescence properties compared to other red‐shifted nanohoops.
•We develop a new price-based dual productivity index.•We compare our dual productivity index with a malmquist primal productivity index.•We compare our dual productivity index with an empirical ...fisher productivity index.•We use US agricultural data to compare the productivity indexes.•We find statistically insignificant differences among the productivity indexes.
A primal (or direct) productivity index is conventionally defined as the ratio of an output quantity index to an input quantity index. There have been attempts in the literature to define and implement dual and indirect productivity indexes based on price changes rather than quantity changes. Although dual and indirect productivity indexes share a common motivation, the measurement of productivity change when prices are easier to measure, or are measured more accurately, than quantities, they differ analytically, from one another and from primal productivity indexes. We introduce a new dual productivity index, inspired by contributions of Konüs and Shephard, and we compare our dual productivity index with a primal productivity index inspired by the work of Malmquist. We also compare these two theoretical productivity indexes with an analogous pair of empirical Fisher productivity indexes. We provide an empirical application to US agricultural productivity growth.
Cycloparaphenylenes, or "carbon nanohoops," are unique conjugated macrocycles with radially oriented π-systems similar to those in carbon nanotubes. The centrosymmetric nature and conformational ...rigidity of these molecules lead to unusual size-dependent photophysical characteristics. To investigate these effects further and expand the family of possible structures, a new class of related carbon nanohoops with broken symmetry is disclosed. In these structures, referred to as
cycloparaphenylenes, a single carbon-carbon bond is shifted by one position in order to break the centrosymmetric nature of the parent
cycloparaphenylenes. Advantageously, the symmetry breaking leads to bright emission in the smaller nanohoops, which are typically non-fluorescent due to optical selection rules. Moreover, this simple structural manipulation retains one of the most unique features of the nanohoop structures-size dependent emissive properties with relatively large extinction coefficients and quantum yields. Inspired by earlier theoretical work by Tretiak and co-workers, this joint synthetic, photophysical, and theoretical study provides further design principles to manipulate the optical properties of this growing class of molecules with radially oriented π-systems.
Silica particles were prepared by flame spray pyrolysis (FSP) as a support for nickel catalysts. The impact of precursor feed rate (3, 5 and 7 mL/min) during FSP on the silica characteristics and the ...ensuing effect on catalytic performance for the carbon dioxide, or dry, reforming of methane (DRM) was probed. Increasing the precursor feed rate: (i) progressively lowered the silica surface area from ≈340 m2/g to ≈240 m2/g; (ii) altered the silanol groups on the silica surface; and (iii) introduced residual carbon-based surface species to the sample at the highest feed rate. The variations in silica properties altered the (5 wt %) nickel deposit characteristics which in turn impacted on the DRM reaction. As the silica surface area increased, the nickel dispersion increased which improved catalyst performance. The residual carbon-based species also appeared to improve nickel dispersion, and in turn catalyst activity, although not to the same extent as the change in silica surface area. The findings illustrate both the importance of silica support characteristics on the catalytic performance of nickel for the DRM reaction and the capacity for using FSP to control these characteristics.
Protein-protein interactions effectively mediate molecular function. They are the result of specific interactions between protein interfaces and are maintained by the action of evolutionary pressure ...on the regions of the interacting proteins that contribute to binding. For the most part, selection restricts amino acid replacements, accounting for the conservation of binding interfaces. However, in some cases, change in one protein will be mitigated by compensatory change in its binding partner, maintaining function in the face of evolutionary change. There have been several attempts to use correlations in sequence evolution to predict interactions of proteins. Most commonly, these approaches use the entire sequence to identify correlations and so infer probable binding. However, other factors such as shared evolutionary history and similarities in the rates of evolution confound these whole-sequence-based approaches. Here, we discuss recent work on this topic and argue that both site-specific coevolutionary change and whole-sequence evolution contribute to evolutionary signals in sets of interacting proteins. We discuss the relative effects of both types of selection and how they might be identified. This permits an integrated view of protein-protein interactions, their evolution, and coevolution.
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