bluuebunny/crossref_metadata_2025_split huggingface dataset:
The polarization-encoded self-coherent camera
Authors: Bos S. P. 
Published: January 2021

Context. The exploration of circumstellar environments by means of direct imaging to search for Earth-like exoplanets is one of the challenges of modern astronomy. One of the current limitations are evolving non-common path aberrations (NCPA) that originate from optics downstream of the main wavefront sensor. Measuring these NCPA with the science camera during observations is the preferred solution for minimizing the non-common path and maximizing the science duty cycle. The self-coherent camera (SCC) is an integrated coronagraph and focal-plane wavefront sensor that generates wavefront information-encoding Fizeau fringes in the focal plane by adding a reference hole (RH) in the Lyot stop. However, the RH is located at least 1.5 pupil diameters away from the pupil center, which requires the system to have large optic sizes and results in low photon fluxes in the RH.
Aims. Here, we aim to show that by featuring a polarizer in the RH and adding a polarizing beamsplitter downstream of the Lyot stop, the RH can be placed right next to the pupil. This greatly increases the photon flux in the RH and relaxes the requirements on the optics size due to a smaller beam footprint. We refer to this new variant of the SCC as the polarization-encoded self-coherent camera (PESCC).
Methods. We study the performance of the PESCC analytically and numerically, and compare it, where relevant, to the SCC. We look into the specific noise sources that are relevant for the PESCC and quantify their effect on wavefront sensing and control (WFSC).
Results. We show analytically that the PESCC relaxes the requirements on the focal-plane sampling and spectral resolution with respect to the SCC by a factor of 2 and 3.5, respectively. Furthermore, we find via our numerical simulations that the PESCC has effectively access to ∼16 times more photons, which improves the sensitivity of the wavefront sensing by a factor of ∼4. We identify the need for the parameters related to the instrumental polarization and differential aberrations between the beams to be tightly controlled – otherwise, they limit the instrument’s performance. We also show that without additional measurements, the RH point-spread function (PSF) can be calibrated using PESCC images, enabling coherent differential imaging (CDI) as a contrast-enhancing post-processing technique for every observation. In idealized simulations (clear aperture, charge two vortex coronagraph, perfect DM, no noise sources other than phase and amplitude aberrations) and in circumstances similar to those of space-based systems, we show that WFSC combined with CDI can achieve a 1σ raw contrast of ∼3 × 10−11 − 8 × 10−11 between 1 and 18 λ/D.
Conclusions. The PESCC is a powerful, new focal-plane wavefront sensor that can be relatively easily integrated into existing ground-based and future space-based high-contrast imaging instruments.
The prebiotic molecular inventory of Serpens SMM1
Authors: Ligterink N. F. W. , Ahmadi A. , Coutens A. , Tychoniec Ł. , Calcutt H. , van Dishoeck E. F. , Linnartz H. , Jørgensen J. K. , Garrod R. T. , Bouwman J. 
Published: January 2021

Aims. Methyl isocyanate (CH3NCO) and glycolonitrile (HOCH2CN) are isomers and prebiotic molecules that are involved in the formation of peptide structures and the nucleobase adenine, respectively. These two species are investigated to study the interstellar chemistry of cyanides (CN) and isocyanates (NCO) and to gain insight into the reservoir of interstellar prebiotic molecules.
Methods. ALMA observations of the intermediate-mass Class 0 protostar Serpens SMM1-a and ALMA-PILS data of the low-mass Class 0 protostar IRAS 16293B are used. Spectra are analysed with the CASSIS line analysis software package in order to identify and characterise molecules.
Results. CH3NCO, HOCH2CN, and various other molecules are detected towards SMM1-a. HOCH2CN is identified in the PILS data towards IRAS 16293B in a spectrum extracted at a half-beam offset position from the peak continuum. CH3NCO and HOCH2CN are equally abundant in SMM1-a at [X]/[CH3OH] of 5.3 × 10−4 and 6.2 × 10−4, respectively. A comparison between SMM1-a and IRAS 16293B shows that HOCH2CN and HNCO are more abundant in the former source, but CH3NCO abundances do not differ significantly. Data from other sources are used to show that the [CH3NCO]/[HNCO] ratio is similar in all these sources within ~10%.
Conclusions. The new detections of CH3NCO and HOCH2CN are additional evidence for a large interstellar reservoir of prebiotic molecules that can contribute to the formation of biomolecules on planets. The equal abundances of these molecules in SMM1-a indicate that their formation is driven by kinetic processes instead of thermodynamic equilibrium, which would drive the chemistry to one product. HOCH2CN is found to be much more abundant in SMM1-a than in IRAS 16293B. From the observational data, it is difficult to indicate a formation pathway for HOCH2CN, but the thermal Strecker-like reaction of CN− with H2CO is a possibility. The similar [CH3NCO]/[HNCO] ratios found in the available sample of studied interstellar sources indicate that these two species are either chemically related or their formation is affected by physical conditions in the same way. Both species likely form early during star formation, presumably via ice mantle reactions taking place in the dark cloud or when ice mantles are being heated in the hot core. The relatively high abundances of HOCH2CN and HNCO in SMM1-a may be explained by a prolonged stage of relatively warm ice mantles, where thermal and energetic processing of HCN in the ice results in the efficient formation of both species.
Semianalytical model for planetary resonances
Authors: Gallardo Tabaré , Beaugé Cristián , Giuppone Cristian A. 
Published: January 2021

Context. Planetary resonances are a common dynamical mechanism acting on planetary systems. However, no general model for describing their properties exists, particularly for commensurabilities of any order and arbitrary eccentricity and inclination values.
Aims. We present a semianalytical model that describes the resonance strength, width, location and stability of fixed points, and periods of small-amplitude librations. The model is valid for any two gravitationally interacting massive bodies, and is thus applicable to planets around single or binary stars.
Methods. Using a theoretical framework in the Poincaré and Jacobi reference system, we developed a semianalytical method that employs a numerical evaluation of the averaged resonant disturbing function. Validations of the model are presented that compare its predictions with dynamical maps for real and fictitious systems.
Results. The model describes many dynamical features of planetary resonances very well. Notwithstanding the good agreement found in all cases, a small deviation is noted in the location of the resonance centers for circumbinary systems. As a consequence of its application to the HD 31527 system, we found that the updated best-fit solution leads to a high-eccentricity stable libration between the middle and outer planets inside the 16/3 mean-motion resonance (MMR). This is the first planetary system whose long-term dynamics appears dominated by such a high-order commensurability. In the case of circumbinary planets, the overlap of N/1 mean-motion resonances coincides very well with the size of the global chaotic region close to the binary, as well as its dependence on the mutual inclination.
Illumination of the accretion disk in black hole binaries: An extended jet as the primary source of hard X-rays
Authors: Reig P. , Kylafis N. D. 
Published: January 2021

Context.The models that seek to explain the reflection spectrum in black hole binaries usually invoke a point-like primary source of hard X-rays. This source illuminates the accretion disk and gives rise to the discrete (lines) and continuum-reflected components.Aims.The main goal of this work is to investigate whether the extended, mildly relativistic jet that is present in black hole binaries in the hard and hard-intermediate states is the hard X-ray source that illuminates the accretion disk.Methods.We use a Monte Carlo code that simulates the process of inverse Compton scattering in a mildly relativistic jet rather than in a “corona” of some sort. Blackbody photons from the thin accretion disk are injected at the base of the jet and interact with the energetic electrons that move outward with a bulk velocity that is a significant fraction of the speed of light.Results.Despite the fact that the jet moves away from the disk at a mildly relativistic speed, we find that approximately 15−20% of the input soft photons are scattered, after Comptonization, back toward the accretion disk. The vast majority of the Comptonized, back-scattered photons escape very close to the black hole (h ≲ 6 rg, wherergis the gravitational radius), but a non-negligible amount escape at a wide range of heights. At high heights,h ∼ 500−2000 rg, the distribution falls off rapidly. The high-height cutoff strongly depends on the width of the jet at its base and is almost insensitive to the optical depth. The disk illumination spectrum is softer than the direct jet spectrum of the radiation that escapes in directions that do not encounter the disk.Conclusions.We conclude that an extended jet is an excellent candidate source of hard photons in reflection models.
Mammalian cell proliferation requires noncatalytic functions of O-GlcNAc transferase
Authors: Levine Zebulon G. , Potter Sarah C. , Joiner Cassandra M. , Fei George Q. , Nabet Behnam , Sonnett Matthew , Zachara Natasha E. , Gray Nathanael S. , Paulo Joao A. , Walker Suzanne 
Published: January 2021

SignificanceMammalian cells contain only one glycosyltransferase, OGT, that operates in the nucleus and cytoplasm rather than the secretory pathway. OGT is required for cell proliferation, but a basic unanswered question is which OGT functions are essential. This question is challenging to address because OGT has thousands of glycosylation substrates, two different enzymatic activities, and a large number of binding partners. Here, by establishing genetic tools to replace endogenous OGT with variants that preserve only a subset of its activities, we show that only a low level of glycosylation activity is required to maintain cell viability; however, cell proliferation requires noncatalytic OGT function(s). The ability to replace OGT with variants provides a path to identifying its essential substrates and binding partners.
Agroecological practices for whole-system sustainability
Authors: Hawes Cathy , Iannetta Pietro P.M. , Squire Geoffrey R. 
Published: January 2021

Abstract
Current food production systems are major contributors to the environmental degradation that leads to climate change and biodiversity loss. Levels of production required for future food security cannot be met by further increases in inputs of non-renewable resources. The world’s food crops must therefore be managed in a sustainable way that maintains long-term ecological functioning, including nutrient, carbon and water cycles, soil quality, primary productivity, microbe-plant associations, pest and pathogen regulation, pollination and arable food web resilience. All of these are determined by agronomic practices at local and regional scales, and all are sustained by the abundance, diversity and functional composition of plants, microbes and invertebrates in the farmed ecosystem. Presence of viable populations and communities of these organisms is therefore essential for system resilience. Long-term sustainability must rely more heavily on the internal generation of products and regulatory ecosystem services than on external inputs. Fully closed systems are impossible to achieve in agriculture as the product is removed for human consumption. There is ample evidence, however, that semi-closed, regenerative, systems can harness the ecosystem services provided by functional biodiversity to enhance crop production whilst simultaneously improving environmental quality. Here, agroecological alternatives to intensive farming practices are reviewed, focusing on key functional indicators and whole-system integration of practical management options designed to achieve multiple beneficial outcomes at field and farm scales.
Recent progress in in situ/operando analysis tools for oxygen electrocatalysis
Authors: Yoo Ji Mun , Shin Heejong , Park Subin , Sung Yung-Eun 
Published: January 2021

AbstractFuel cell and water electrolyzer technology have been intensively investigated in the last decades toward sustainable and renewable energy conversion systems. For improved device performance and service life, nanostructured electrocatalysts on electrode have been extensively developed based on the principle of structure-activity-stability correlation. However, overall device efficiency is seriously hindered by sluggish oxygen electrocatalysis, including oxygen reduction reaction and oxygen evolution reaction. As a result, tremendous efforts have been made to construct the most active surfaces with robust durability. For knowledge-based approaches toward systematic development of highly functional nanostructures, fundamental principles within oxygen electrocatalysis should be uncovered including reaction intermediate, active site structures, and atomic dissolution from surface. However, conventionalex situcharacterizations only provide a static picture of electrode surfaces without electrocatalysis. On the other hand,in situ/operandoanalyses allow us to directly monitor dynamics on electrode under operating conditions. In this review, we will introduce a set ofin situ/operandoanalytical tools and summarize their contribution to fundamental researches on oxygen electrocatalysis. Taking both precious and non-precious electrocatalyst materials as examples, the most impending issues in oxygen electrocatalysis are covered within situ/operandostudies to highlight the power ofin situ/operandotechniques and encourage further efforts on advanced analytic techniques.
Measuring plasma-generated ·OH and O atoms in liquid using EPR spectroscopy and the non-selectivity of the HTA assay
Authors: Myers B , Ranieri P , Smirnova T , Hewitt P , Peterson D , Herrera Quesada M , Lenker E , Stapelmann K 
Published: January 2021

Abstract
Plasma-generated hydroxyl radicals (·OH) and oxygen atoms (O) produced by the COST reference plasma jet, a micro-scaled atmospheric pressure plasma jet, were investigated using a variety of experimental techniques. Several gas admixtures were studied to distinguish the contributions of the two reactive oxygen species. Large discrepancies between inferred aqueous ·OH densities were noted when using a 2-hydroxyterephthalic acid (HTA) fluorescence assay and electron paramagnetic resonance (EPR) measurements with the spin trap 5,5-dimethyl-1-pyrroline N-oxide—especially when oxygen was present in the feed gas. A series of follow-up experiments including optical emission spectroscopy, H2O2 quantification, and EPR measurements of atomic oxygen using the spin trap 2,2,6,6-tetramethylpiperidine, revealed that the inconsistencies between the measured aqueous ·OH were likely due to the propensity of atomic oxygen to hydroxylate TA in a manner indistinguishable from ·OH. This renders the HTA assay non-selective when both ·OH radicals and atomic oxygen are present, which we report for all three gas admixtures in our experiments. Additionally, considerable degradation of both HTA and the spin adducts measured using EPR spectroscopy was apparent, meaning actual radical densities in the plasma-treated liquid may be considerably higher than implied. Degradation rates compared favorably to previously measured gas phase densities of atomic oxygen in the predecessor of the COST jet and reported degradation of other chemical probes. These results show the prolific role of atomic oxygen in plasma-induced liquid chemistry and caution against diagnostic techniques that are unable to account for it.
Superconductivity in topological insulator β-PdBi2 under pressure
Authors: Suzuki Ai , Taguchi Tomoya , Li Huan , Wang Yanan , Ishii Hirofumi , Liao Yen-Fa , Goto Hidenori , Eguchi Ritsuko , Kubozono Yoshihiro 
Published: January 2021

Abstract
The topological insulator PdBi2 exhibits two different crystal phases at ambient pressure, i.e., ‘α-PdBi2’ and ‘ -PdBi2’. The pressure dependence of crystal structure and superconductivity of α-PdBi2 has been fully elucidated thus far. However, the physical properties of β-PdBi2 crystals under pressure have not been sufficiently investigated. In this study, we fully investigate the crystal structure and superconductivity of β-PdBi2 under pressure based on synchrotron x-ray diffraction (XRD) patterns. The temperature dependence of β-PdBi2 indicates its superconductivity with a superconducting transition temperature (T
c) as high as 4.10 K, and its crystal structure is tetragonal [space group of I4/mmm (no. 139)]. The XRD patterns at 0–22.0 GPa indicate no structural phase transitions, and the unit cell volume shrinks monotonically with pressure, unlike the behavior of α-PdBi2. Furthermore, α-PdBi2 transformed to β-PdBi2 under pressure. This suggests that β-PdBi2 is stable under pressure. The superconductivity is clearly observed at 0–11.8 GPa, and the value of T
c is almost constant at ∼4.4 K. The temperature dependence of the upper critical field at ambient pressure and 10.7 GPa indicates that the superconductivity is not attributed to a simple s-wave dirty limit but an s-wave clean or p-wave polar model. This is the first systematic study of superconductivity of topological insulator β-PdBi2 under pressure.
Magnetoelastic coupling and critical behavior of some strongly correlated magnetic systems
Authors: Dutta Kishore , Singh Rohit 
Published: January 2021

Abstract
The strongly correlated magnetic systems are attracting continuous attention in current condensed matter research due to their very compelling physics and promising technological applications. Being a host to charge, spin, and lattice degrees of freedom, such materials exhibit a variety of phases, and investigation of their physical behavior near such a phase transition bears an immense possibility. This review summarizes the recent progress in elucidating the role of magnetoelastic coupling on the critical behavior of some technologically important class of strongly correlated magnetic systems such as perovskite magnetites, uranium ferromagnetic superconductors, and multiferroic hexagonal manganites. It begins with encapsulation of various experimental findings and then proceeds toward describing how such experiments motivate theories within the Ginzburg–Landau phenomenological picture in order to capture the physics near a magnetic phase transition of such systems. The theoretical results that are obtained by implementing Wilson’s renormalization-group to nonlocal Ginzburg–Landau model Hamiltonians are also highlighted. A list of possible experimental realizations of the coupled model Hamiltonians elucidates the importance of spin–lattice coupling near a critical point of strongly correlated magnetic systems.
Mn-induced spin glass behavior in metallic Ir3Sn7−x
Mn
x
Authors: Speer Smita , Marshall Madalynn , Chang Hong , Nepal Roshan , Blawat Joanna , Chapai Ramakanta , Gui Xin , Xie Weiwei , Jin Rongying 
Published: January 2021

Abstract
Transition metal stannides are usually semiconductors with a narrow band gap. We report experimental investigation on metallic Ir3Sn7–x
Mn
x
(x = 0 and 0.56). Single crystal x-ray diffraction refinement indicates that Ir3Sn7–x
Mn
x
crystals form a cubic structure (space group Im

3

̄

m) with the lattice parameter a = 9.362(4) Å for x = 0 and 9.328(6) Å for x = 0.56. The electrical resistivity shows metallic behavior between 2 K and 300 K with T
2 dependence at T < 30 K for x = 0, reflecting the Fermi-liquid ground state. While Ir3Sn7 exhibits weak diamagnetism, partial substitution of Sn by Mn results in spin glass behavior in Ir3Sn7−x
Mn
x
below T
g ∼ 13 K for x = 0.56. Remarkably, an upturn in the resistivity is observed in x = 0.56 below ∼2T
g, suggesting strong spin fluctuation. This fluctuation is suppressed by the application of magnetic field, which is reflected in the observation of negative magnetoresistance. The unusual properties that emerge due to Mn doping are discussed.
Albumin diffusivity coefficient estimation in imitated porous structure of interstitial space by integration of albumin diffusion model (ADM) to electrical impedance tomography (EIT)
Authors: Dharma Irfan Aditya , Kawashima Daisuke , Baidillah Marlin Ramadhan , Darma Panji Nursetia , Takei Masahiro 
Published: January 2021

Abstract
Albumin diffusivity coefficient

D

I

a

in imitated porous structure of interstitial space has been estimated by means of the integration of albumin diffusion model (ADM) to electrical impedance tomography (EIT) (iADM-EIT) under five different porosity

ϕ

conditions (from

ϕ
1

=

0.922 to

ϕ
5

=

0.990) for transport phenomena quantification. The iADM-EIT was conducted by applying an iterative curve-fitting between spatio-temporal albumin concentration

C

I

a

derived from ADM and spatio-temporal distribution of conductivity difference

Δ

σ

reconstructed by EIT. The essential point of the iADM-EIT is the quantification of experimental

C

I

ex

a

from

Δ

σ

by establishing a constitutive relationship among

C

I

ex

a

,

Δ

σ

, and

ϕ

. ADM is developed based on Fick’s second law implemented in Krogh tissue cylinder. EIT is performed to image the

Δ

σ

caused by increase of

C

I

a

due to albumin diffusion phenomenon from a capillary to the imitated porous structure. The imitated porous structure is manufactured with agarose gel in a dynamic phantom including a capillary. As a result, the relative albumin diffusivity coefficient

D

I

a

/

D

0

a

(

D

0

a

: free diffusivity of albumin coefficient) is increased with the increase of

ϕ

in the range from 0.271 to 0.694, which are correspondent to the literature data with percent average relative error

δ

= 6.83 ± 2.72%.
Palladium zero-mode waveguides for optical single-molecule detection with nanopores
Authors: Klughammer Nils , Dekker Cees 
Published: January 2021

Abstract
Holes in metal films do not allow the propagation of light if the wavelength is much larger than the hole diameter, establishing such nanopores as so-called zero-mode waveguides (ZMWs). Molecules, on the other hand, can still pass through these holes. We use this to detect individual fluorophore-labelled molecules as they travel through a ZMW and thereby traverse from the dark region to the illuminated side, upon which they emit fluorescent light. This is beneficial both for background suppression and to prevent premature bleaching. We use palladium as a novel metal-film material for ZMWs, which is advantageous compared to conventionally used metals. We demonstrate that it is possible to simultaneously detect translocations of individual free fluorophores of different colours. Labelled DNA and protein biomolecules can also be detected at the single-molecule level with a high signal-to-noise ratio and at high bandwidth, which opens the door to a variety of single-molecule biophysics studies.