Local Analogs Research Articles

FAST H i 21 cm Study of Blueberry Galaxies

Green Peas (GPs) and blueberry galaxies (BBs) are thought to be local analogs (z < 0.1) of high redshift Lyα emitters. H i study of these can help us understand the star formation in the primordial Universe. In this Letter, we present the results of H i 21 cm study of 28 high specific star formation rate (sSFR ≳ 10−8yr −1) BBs at z ≲ 0.05 with the Five-hundred-meter Aperture Spherical radio Telescope. We report significant H i detection towards two BBs, namely J1026+0426 and J1132+0809, and discuss possible H i contribution from neighboring galaxies. The median 3σ upper limit of ∼2.0 × 108 M ⊙ was obtained on H i mass for galaxies with nondetections. We find BBs tend to have lower H i-to-stellar-mass ratio or gas fraction (f H i ) than expected from f H i –sSFR and f H i –M * relations for main-sequence galaxies. The BBs also have a median 3σ upper limit on H i gas depletion timescale (τ H i ) ∼ 0.5 Gyr, about 1 order of magnitude lower than τ H i for local main-sequence galaxies. We find a significantly low H i detection rate of 2/28 (7.1 −4.6+9.4 %) towards these galaxies, which is similar to previous H i studies of low redshift GPs of high ionization parameter indicator, O32 ≡ O[iii]λ5007/O[ii]λ3727 ratios ≳10.

The ultraviolet luminosity function of star-forming galaxies between redshifts of 0.4 and 0.6

Abstract We combine ultraviolet imaging of the 13H survey field, taken with the XMM-Newton Optical Monitor telescope (XMM-OM) and the Neil Gehrels Swift Observatory Ultraviolet and Optical Telescope (UVOT) in the UVM2 band, to measure rest-frame ultraviolet 1,500 Å luminosity functions of star-forming galaxies with redshifts z between 0.4 and 0.6. In total the UVM2 imaging covers a sky area of 641 arcmin2, and we detect 273 galaxies in the UVM2 image with 0.4 &amp;lt; z &amp;lt; 0.6. The luminosity function is fit by a Schechter function with best-fit values for the faint end slope $\alpha =-1.8^{+0.4}_{-0.3}$ and characteristic absolute magnitude $M^{*} = -19.1^{+0.3}_{-0.4}$. In common with XMM-OM based studies at higher redshifts, our best-fitting value for M* is fainter than previous measurements. We argue that the purging of active galactic nuclei from the sample, facilitated by the co-spatial X-ray survey carried out with XMM-Newton is important for the determination of M*. At the brightest absolute magnitudes (M1500 &amp;lt; −18.5) the average UV colour of our galaxies is consistent with that of minimal-extinction local analogues, but the average UV colour is redder for galaxies at fainter absolute magnitudes, suggesting that higher levels of dust attenuation enter the sample at absolute magnitudes somewhat fainter than M*.

Evidence of Extreme Ionization Conditions and Low Metallicity in GHZ2/GLASS-Z12 from a Combined Analysis of NIRSpec and MIRI Observations

GHZ2/GLASS-z12, one of the most distant galaxies found in JWST observations, has been recently observed with both the NIRSpec and MIRI spectrographs, establishing a spectroscopic redshift z spec = 12.34 and making it the first system at z > 10 with complete spectroscopic coverage from rest-frame UV to optical wavelengths. This galaxy is identified as a strong C iv λ1549 emitter (EW = 46 Å) with many other detected emission lines, such as N iv] λ1488, He ii λ1640, O iii] λ λ1661,1666, N iii] λ1750, C iii] λ λ1907,1909, [O ii] λ λ3726,3729, [Ne iii] λ3869, [O iii] λ λ4959,5007, and Hα, including a remarkable detection of the O iii Bowen fluorescence line at rest frame λ = 3133 Å. We analyze in this paper the joint NIRSpec + MIRI spectral data set. Combining six optical strong-line diagnostics (namely R2, R3, R23, O32, Ne3O2, and Ne3O2Hd), we find extreme-ionization conditions, with log10 ([O III] λ λ4959,5007/[O II] λ λ3726,3729) = 1.39 ± 0.19 and log10 ([Ne III] λ3869/[O II] λ λ3726,3729) = 0.37 ± 0.18 in stark excess compared to typical values in the interstellar medium (ISM) at lower redshifts. These line properties are compatible either with an active galactic nucleus (AGN) or with a compact, very dense star-forming environment (ΣSFR ≃ 102–103 M ⊙ yr−1 kpc−2 and ΣM* ≃ 104–105 M ⊙ pc−2), with a high ionization parameter (log10(U) =−1.75 ± 0.16), a high ionizing photon production efficiency log(ξion)=25.7−0.1+0.3 , and a low gas-phase metallicity (also confirmed by the direct, T e method) ranging between 4% and 11% Z ⊙, indicating a rapid chemical enrichment of the ISM in the past few megayears. These properties also suggest that a substantial amount of ionizing photons (∼10%) are leaking outside of GHZ2 and starting to reionize the surrounding intergalactic medium, possibly due to strong radiation-driven winds. The general lessons learned from GHZ2 are the following: (i) the UV-to-optical combined nebular indicators are broadly in agreement with UV-only or optical-only indicators; (ii) UV+optical diagnostics fail to discriminate between an AGN and star formation in a low-metallicity, high-density, and extreme-ionization environment; and (iii) comparing the nebular line ratios with local analogs may be approaching its limits at z ≳ 10, as this approach is potentially challenged by the unique conditions of star formation experienced by galaxies at these extreme redshifts.

Disk Turbulence and Star Formation Regulation in High-z Main-sequence Analog Galaxies

The gas-phase velocity dispersions in disk galaxies, which trace turbulence in the interstellar medium, are observed to increase with lookback time. However, the mechanisms that set this rise in turbulence are observationally poorly constrained. To address this, we combine kiloparsec-scale Atacama Large Millimeter/submillimeter Array observations of CO(3−2) and CO(4−3) with Hubble Space Telescope observations of Hα to characterize the molecular gas and star formation properties of seven local analogs of main-sequence galaxies at z ∼ 1–2, drawn from the DYNAMO sample. Investigating the “molecular gas main sequence” on kiloparsec scales, we find that galaxies in our sample are more gas-rich than local star-forming galaxies at all disk positions. We measure beam-smearing-corrected molecular gas velocity dispersions and relate them to the molecular gas and star formation rate surface densities. Despite being relatively nearby (z ∼ 0.1), DYNAMO galaxies exhibit high velocity dispersions and gas and star formation rate surface densities throughout their disks, when compared to local star-forming samples. Comparing these measurements to predictions from star formation theory, we find very good agreements with the latest feedback-regulated star formation models. However, we find that theories that combine dissipation of gravitational energy from radial gas transport with feedback overestimate the observed molecular gas velocity dispersions.

X-ray observations of Blueberry galaxies

Context. Compact star-forming galaxies were dominant galaxy types in the early Universe. Blueberry galaxies (BBs) represent their local analogues, being very compact and having intense star formation. Aims. Motivated by high X-ray emission recently found in other analogical dwarf galaxies, called Green Peas, we probed the X-ray properties of BBs to determine if their X-ray emission is consistent with the empirical laws for star-forming galaxies. Methods. We performed the first X-ray observations of a small sample of BBs with the XMM-Newton satellite. Spectral analysis for detected sources and upper limits measured via Bayesian-based analysis for very low-count measurements were used to determine the X-ray properties of our galaxy sample. Results. Clear detection was obtained for only two sources, with one source exhibiting an enhanced X-ray luminosity to the scaling relations. For the remaining five sources, only an upper limit was constrained, suggesting BBs to be rather underluminous as a whole. Our analysis shows that the large scatter cannot be easily explained by the stochasticity effects. While the bright source is above (and inconsistent with) the expected distribution at almost the 99% confidence level, the upper limits of the two sources are below the expected distribution. Conclusions. These results indicate that the empirical relations between the star formation rate, metallicity, and X-ray luminosity might not hold for BBs with uniquely high specific star formation rates. One possible explanation could be that the BBs may not be old enough to have a significant X-ray binary population. The high luminosity of the only bright source can then be caused by an additional X-ray source, such as a hidden active galactic nucleus or more extreme ultraluminous X-ray sources.

Spatiotemporal Bragg gratings forming inside a nonlinear dispersive medium.

We show that a spatiotemporal Bragg grating can be created inside a nonlinear dispersive medium (such as silica fibers) by launching a periodic train of pump pulses that travel as fundamental solitons. We develop a theoretical model and use it to find the band structure of such gratings. We study the interaction of a probe pulse with the Bragg grating, both within and outside of momentum gaps. We also show that a photonic analog of the Anderson localization is possible when a disorder is introduced into a spatiotemporal Bragg grating.

Interaction Effects on the Dynamical Anderson Metal-Insulator Transition Using Kicked Quantum Gases.

Understanding the interplay of interaction and disorder in quantum transport poses long-standing scientific challenges for theory and experiment. While highly controlled ultracold atomic platforms combining atomic interactions with spatially disordered lattices have led to remarkable advances, the extension of such controlled studies to phenomena in high-dimensional disordered systems, such as the three-dimensional Anderson metal-insulator transition has been limited. Kicked quantum gases provide an alternate experimental platform that captures the Anderson model in momentum space and features dynamical localization as the analog of Anderson localization. Here, we utilize a momentum space lattice platform using quasiperiodically kicked ultracold atomic gases to experimentally investigate interaction effects on the three-dimensional dynamical Anderson metal-insulator transition. We observe interaction-driven subdiffusion and a divergence of delocalization onset time on approaching the phase boundary. Mean-field numerical simulations show qualitative agreement with experimental observations, but with significant quantitative deviations.

The exosphere of Mars can be tracked by a high-spectral resolution telescope, such as the Line Emission Mapper

Abstract Mars provides our local analogue for unmagnetized terrestrial planets and is thus key to understanding the habitability of exoplanets. The lack of a global magnetic field means that the atmosphere interacts directly with the solar wind, causing significant loss of the atmosphere. While in situ measurements provide a wealth of detailed local information, they are limited in deriving the global picture. In contrast, remote X-ray observations can provide important global instantaneous coverage over multiple seasons and sampling different solar wind. Previous XMM-Newton observations have detected significant flux via the solar wind charge exchange emission (SWCX) mechanism from an extended planetary halo, and from atmospheric fluorescence. In contrast, Chandra observations only detected a low-luminosity disk and a faint halo. It is postulated that these observational differences are due to transient solar wind with increased heavy ion fractions. Here, we present simulated spectra for the proposed NASA mission Line Emission Mapper, of both halo and disk regions, under quiet and transient solar wind. We show that even under moderate solar wind conditions, both SWCX and fluorescence emission lines are readily detected above the background, providing new insights into the loss of planetary atmospheres and the molecular composition of less well-characterised atmospheric abundances.

Blueberry galaxies up to 200 Mpc and their optical and infrared properties

Context. Dwarf highly star-forming galaxies (SFGs) dominated the early Universe and are considered the main driver of its reionization. However, direct observations of these distant galaxies are mainly confined to rest-frame ultraviolet and visible light, limiting our understanding of their complete properties. Therefore, it is still paramount to study their local analogs, the green pea (GP) and blueberry (BB) galaxies. Aims. This work aims to expand our knowledge of BBs by identifying a new sample that is closer and in the southern sky. Methods. In addition to the already known BBs, this new sample will allow for a statistically significant study of their properties probed by visible and infrared (IR) light. By utilizing the HECATE catalog, which provides optical and IR photometry and characterization of galaxies, along with data from Pan-STARSS and SDSS, this study selects and analyzes a new sample of BBs. We employed spectral energy distribution fitting to derive homogeneous measurements of star-formation rates and stellar masses. Additionally, we measured emission-line fluxes, including He II λ4686, through spectral fitting. Results. Through this work, we identified 48 BBs, of which 40 were first recognized as such, with the nearest at 19 Mpc. Fourteen of the BBs are in the south sky. The BBs tend to be extremely IR red in both WISE W1 – W2 and W2 – W3 colors, distinguishing them from typical SFGs. Dwarf SFGs with higher specific star-formation rates tend to have redder IR colors. Conclusions. Blueberry galaxies stand out as the most intensely star-forming sources in the local Universe among dwarf galaxies. They are intrinsically bluer in visible light, redder in the infrared, and less massive. They also have higher specific star-formation rates, equivalent widths, lower metallicities, and the most strongly ionized interstellar medium compared to typical SFGs and GPs.

Asymptotically compatible energy of variable-step fractional BDF2 scheme for the time-fractional Cahn–Hilliard model

Abstract A novel discrete gradient structure of the variable-step fractional BDF2 formula approximating the Caputo fractional derivative of order $\alpha \in (0,1)$ is constructed by a local-nonlocal splitting technique, that is, the fractional BDF2 formula is split into a local part analogue to the two-step backward differentiation formula (BDF2) of the first derivative and a nonlocal part analogue to the L1-type formula of the Caputo derivative. Then a local discrete energy dissipation law of the variable-step fractional BDF2 implicit scheme is established for the time-fractional Cahn–Hilliard model under a weak step-ratio constraint $0.3960\le \tau _{k}/\tau _{k-1}&amp;lt;r^{*}(\alpha )$, where $\tau _{k}$ is the $k$th time-step size and $r^{*}(\alpha )\ge 4.660$ for $\alpha \in (0,1)$. The present result provides a practical answer to the open problem in [SINUM, 57: 218-237, Remark 6] and significantly relaxes the severe step-ratio restriction [Math. Comp., 90: 19–40, Theorem 3.2]. More interestingly, the discrete energy and the corresponding energy dissipation law are asymptotically compatible with the associated discrete energy and the energy dissipation law of the variable-step BDF2 method for the classical Cahn–Hilliard equation, respectively. To the best of our knowledge, such type energy dissipation law is established at the first time for the variable-step L2 type formula of Caputo’s derivative. Numerical examples with an adaptive stepping procedure are provided to demonstrate the accuracy and the effectiveness of our proposed method.

Extreme-emission-line galaxies in the MUSE Hubble Ultra Deep Field Survey

We aim to apply a methodology to build a sample of extreme-emission-line galaxies (EELGs) using integral field spectroscopy data. In this work, we followed the spectroscopic criteria corresponding to EELG selection and used the MUSE Hubble Ultra-Deep field survey, which includes the deepest spectroscopic survey ever performed. Objects in the primary (extended) sample were detected requiring a rest-frame equivalent width of EWo geqslant 300 leq EWo leq 300 ) in any of the emission lines of OII OIII or Halpha . A detailed closer inspection of the spectra of the candidates selected has been performed on a one-by-one basis in order to confirm their classification. For this sample, the line fluxes, physical properties, and chemical abundances of the EELGs have been derived, as well as their spatially resolved structure and kinematics. Four (five) of the galaxies in the primary (extended) sample, sim 57$&lt;!PCT!&gt;$ (sim 83$&lt;!PCT!&gt;$), were spatially resolved. Three (none) of them present a clear pattern compatible with rotation. We show how our entire EELG sample shares the same loci defined by high-redshift galaxies (z approx 6-8) for the mass-metallicity relation, illustrating their role as local analogs.

JADES: Insights into the low-mass end of the mass–metallicity–SFR relation at 3 &lt; z &lt; 10 from deep JWST/NIRSpec spectroscopy

We analysed the gas-phase metallicity properties of a sample of low-stellar-mass (log M⋆/M⊙ ≲ 9) galaxies at 3 &lt; z &lt; 10 observed with JWST/NIRSpec as part of the JADES programme in its deep GOODS-S tier. By combining this sample with more massive galaxies at similar redshifts from other programmes, we study the scaling relations between stellar mass (M⋆), oxygen abundance (O/H), and star-formation rate (SFR) for 146 galaxies spanning three orders of magnitude in stellar mass and out to the epoch of early galaxy assembly. We find evidence for a shallower slope at the low-mass end of the mass–metallicity relation (MZR), with 12+log(O/H) = (7.72 ± 0.02) + (0.17 ± 0.03) log(M⋆/108 M⊙), in good agreement with the MZR probed by local analogues of high-redshift systems, such as the ‘Green Pea’ and ‘Blueberry’ galaxies. The inferred slope is well matched by models including ‘momentum-driven’ supernova (SN) winds, suggesting that feedback mechanisms in dwarf galaxies (and at high z) might be different from those in place at higher masses. The evolution in the normalisation is observed to be relatively mild compared to previous determinations of the MZR at z ∼ 3 (∼0.1 − 0.2 dex across the explored mass regime). We observe a deviation from the local fundamental metallicity relation (FMR) for our sample at high redshift, especially at z &gt; 6, with galaxies significantly less enriched than predicted given their M⋆ and SFR (with a median offset in log(O/H) of ∼0.5 dex, significant at ∼5σ). These observations are consistent with an enhanced stochasticity in the gas accretion and star-formation history of high-redshift systems, prompting us to reconsider the nature of the relationship between M⋆, O/H, and SFR in the early Universe.

CLASSY. VIII. Exploring the Source of Ionization with UV Interstellar Medium Diagnostics in Local High-z Analogs* *Based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

In the current JWST era, rest-frame UV spectra play a crucial role in enhancing our understanding of the interstellar medium (ISM) and stellar properties of the first galaxies in the epoch of reionization (z > 6). Here, we compare well-known and reliable optical diagrams sensitive to the main ionization source (i.e., star formation, SF; active galactic nuclei, AGN; and shocks) to UV counterparts proposed in the literature—the so-called “UV–BPT diagrams”—using the HST COS Legacy Archive Spectroscopic SurveY (CLASSY), which is the largest high-quality, high-resolution, and broad-wavelength range atlas of far-UV spectra for 45 local star-forming galaxies. In particular, we explore where CLASSY UV line ratios are located in the different UV diagnostic plots, taking into account state-of-the-art photoionization and shock models, and, for the first time, the measured ISM and stellar properties (e.g., gas-phase metallicity, ionization parameter, carbon abundance, and stellar age). We find that the combination of C iii] λ λ1907,9 He ii λ1640 and O iii] λ1666 can be a powerful tool to separate between SF, shocks, and AGN at subsolar metallicities. We also confirm that alternative diagrams without O iii] λ1666 still allow us to define an SF-locus, with some caveats. Diagrams including C iv λ λ1548,51 should be taken with caution given the complexity of this doublet profile. Finally, we present a discussion detailing the ISM conditions required to detect UV emission lines, visible only in low gas-phase metallicity (12 + log(O/H) ≲ 8.3) and high ionization parameter (log(U) ≳ −2.5) environments. Overall, CLASSY and our UV toolkit will be crucial in interpreting the spectra of the earliest galaxies that JWST is currently revealing.

Exploring X-Ray Properties of Low-metallicity Dwarf Galaxies

One of the primary outstanding questions in extragalactic astronomy is the formation and early evolution of the supermassive black holes that are seen in nearly every massive galaxy. Low-metallicity dwarf galaxies may offer the most representative local analogs to pristine early galaxies, making them a vital tool in probing black hole seed models through the study of the intermediate-mass black holes (IMBHs) possibly hosted therein; though these dwarf galaxies, and the IMBHs they may host, are typically not as well-studied in this context as their higher-metallicity and higher-mass counterparts. In this paper, we explore the X-ray properties of a sample of 37 low-metallicity dwarf galaxies using archival XMM observations, and we compare the properties of this population against a representative sample of higher-metallicity counterparts. We report the detection of 10 sources with 0.3–10 keV luminosity in excess of 1040 erg s−1 within the low-metallicity sample, which we highlight for followup as potential IMBH candidates. Finally, we discuss the differing multiwavelength scaling relations (e.g., L X–L W2, L X–star formation rate) between the two galaxy populations, as well as the sample’s L X as a function of metallicity.

Multiwavelength exploration of Extreme Emission Line Galaxies detected in miniJPAS survey

ABSTRACT Extreme Emission Line Galaxies (EELGs) stand as remarkable objects due to their extremely metal poor environment and intense star formation. Considered as local analogues of high-redshift galaxies in the peak of their star-forming activity, they offer insights into conditions prevalent during the early Universe. Assessment of their stellar and gas properties is therefore of critical importance, which requires the assembly of a considerable sample, comprehending a broad redshift range. The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (JPAS) plays a significant role in assembling such a sample, encompassing ∼8000 $\rm deg^2$ and employing 54 narrow-band optical filters. The present work describes the development and subsequent application of the tools that will be employed in the forthcoming JPAS spectrophotometric data, allowing for the massive and automated characterization of EELGs that are expected to be identified. This fully automated pipeline (requiring only the object coordinates from users) constructs Spectral Energy Distributions (SEDs) by retrieving virtually all the available multiwavelength photometric data archives, employs SED fitting tools, and identifies optical emission lines. It was applied to the sample of extreme line emitters identified in the miniJPAS Survey, and its derived physical properties such as stellar mass and age, coupled with fundamental relations, mirror results obtained through spectral modelling of SDSS spectra. Thorough testing using galaxies with documented photometric measurements across different wavelengths confirmed the pipeline’s accuracy, demonstrating its capability for automated analysis of sources with varying characteristics, spanning brightness, morphology, and redshifts. The modular nature of this pipeline facilitates any addition from the user.

Umbel convexity and the geometry of trees

For every p∈(0,∞), a new metric invariant called umbel p-convexity is introduced. The asymptotic notion of umbel convexity captures the geometry of countably branching trees, much in the same way as Markov convexity, the local invariant which inspired it, captures the geometry of bounded degree trees. Umbel convexity is used to provide a “Poincaré-type” metric characterization of the class of Banach spaces that admit an equivalent norm with Rolewicz's property (β). We explain how a relaxation of umbel p-convexity, called infrasup-umbel p-convexity, plays a role in obtaining compression rate bounds for coarse embeddings of countably branching trees. Local analogues of these invariants - fork p-convexity and infrasup-fork p-convexity - are introduced, and their relationship to Markov p-convexity and relaxations of the p-fork inequality is discussed. The metric invariants are estimated for a large class of Heisenberg groups, and in particular a parallelogram p-convexity inequality is proved for Heisenberg groups over p-uniformly convex Banach spaces. Finally, a new characterization of non-negative curvature is given.

Local analog of the Deligne-Riemann-Roch isomorphism for line bundles in relative dimension 1

We prove a local analog of the Deligne-Riemann-Roch isomorphism in the case of line bundles and relative dimension $1$. This local analog consists in computation of the class of $12$th power of the determinant central extension of a group ind-scheme $\mathcal G$ by the multiplicative group scheme over $\mathbb Q$ via the product of $2$-cocyles in the second cohomology group. These $2$-cocycles are the compositions of the Contou-Carrère symbol with the $\cup$-product of $1$-cocycles. The group ind-scheme $\mathcal{G}$ represents the functor which assigns to every commutative ring $A$ the group that is the semidirect product of the group $A((t))^*$ of invertible elements of $A((t))$ and the group of continuous $A$-automorphisms of $A$-algebra $A((t))$. The determinant central extension naturally acts on the determinant line bundle on the moduli stack of geometric data (proper quintets). A proper quintet is a collection of a proper family of curves over $\operatorname{Spec} A$, a line bundle on this family, a section of this family, a relative formal parameter at the section, a formal trivialization of the bundle at the section that satisfy further conditions.

Temperature and external fields in conceptual density functional theory.

Until quite recently, Conceptual DFT (CDFT) was mainly based on the energy functional, E[N,v], where the number of electrons N and the external potential v are state variables. One of the strengths of CDFT, however, is the ease with which additional and/or different state variables can be incorporated. Here, the incorporation of new variables-namely temperature and external fields-is discussed, outlining the motivation for these extensions, sketching their theoretical/computational context, and presenting some elucidative examples. Using the Grand Canonical Ensemble, finite temperature can be introduced, ameliorating the N-differentiability problem and leading to new well-behaved chemical reactivity concepts. Incorporating temperature as an additional fundamental variable enables us to formulate a novel suite of "thermodynamic" reactivity descriptors, including important concepts like the heat capacity of electronic systems. The mathematical structure underpinning the set of (well-behaved) finite-temperature reactivity indices can guide the formulation of plausible definitions for local analogs of global descriptors. This endeavor is especially significant in the case of local hardness, a concept that has remained elusive since the inception of CDFT. The ever-increasing portfolio of experimental reaction conditions to creatively synthesize new molecules, needs the introduction of various external "fields" like electric and magnetic fields (ε and B), mechanical forces (F) and pressure (P) to describe the state of the chemical system. The conventional energy functional can be expressed in a general form, E[N,v,X], where X denotes the "field". Response functions to changes in the field can then be defined in analogy to classical thermodynamics. The electric field results display a case of a field-induced selectivity in a reaction channel of the Fukui function. Remarkably, atomic electronegativity and hardness in magnetic fields display a piecewise behavior in magnetic fields, associated to configurational jumps upon increasing field strength. The overall compression of their ranges for stronger fields may be insightful when investigating chemistry in extremely high fields. The electronegativity and hardness of diatomics under mechanical force can be traced back to changes in equilibrium distances in the neutral, cationic and anionic state, parallel with the evolution of an intrinsic atomic volume under pressure.

FRET-GP - A Local Measure of the Impact of Transmembrane Peptide on Lipids.

Reconstitution of a transmembrane protein in model lipid systems allows studying its structure and dynamics in isolation from the complexity of the natural environment. This approach also provides a well-defined environment for studying the interactions of proteins with lipids. In this work, we describe the FRET-GP method, which utilizes Förster resonance energy transfer (FRET) to specifically probe the nanoenvironment of a transmembrane domain. The tryptophan residues flanking this domain act as efficient FRET donors, while Laurdan acts as acceptor. The fluorescence of this solvatochromic probe is quantified using generalized polarization (GP) to report on lipid mobility in the vicinity of the transmembrane domain. We applied FRET-GP to study the transmembrane peptide WALP incorporated in liposomes. We found that the direct excitation of Laurdan to its second singlet state strongly contributes to GP values measured in FRET conditions. Removal of this parasitic contribution was essential for proper determination of GPFRET - the local analogue of classical GP parameter. The presence of WALP significantly increased both parameters but the local effects were considerably stronger (GPFRET ≫ GP). We conclude that WALP restricts lipid movement in its vicinity, inducing lateral inhomogeneity in membrane fluidity. WALP was also found to influence lipid phase transition. Our findings demonstrated that FRET-GP simultaneously provides local and global results, thereby enhancing the depth of information obtained from the measurement. We highlight the simplicity and sensitivity of the method, but also discuss its potential and limitations in studying protein-lipid interactions.

Sole brachytherapy for inoperable, recurrent, and irradiated salivary gland cancer

Background and purposeSalivary gland cancers (SGCs) are hard to treat when inoperable, and sole brachytherapy appears to be a promising therapeutic strategy. This study aimed to evaluate the effectiveness, safety, and capability of pain palliation using sole brachytherapy for inoperable, recurrent, and irradiated SGCs. Materials and methodsPatients with inoperable SGCs treated using sole brachytherapy at Peking University School and Hospital of Stomatology were retrospectively included. Patients were divided into primary and recurrent groups and irradiated and non-irradiated groups. Local control (LC), overall survival (OS), radiation-relevant toxicities, and Visual Analogue Scale (VAS) score for pain, were recorded and evaluated. ResultsA total of 176 patients from 2006 to 2020 were included. The 5-year LC rate was 48.6 %; for the primary, recurrent, non-irradiated and irradiated groups, the rates were 72.6 %, 39.5 %, 56.8 %, and 34.5 %, respectively. The 5-year OS rates was 52.6 %; for the primary, recurrent, non-irradiated, and irradiated groups, the rates were 62.9 %, 48.6 %, 58.9 %, and 42.3 %, respectively. The mean ± standard deviation of posttreatment VAS score of pain was 2.154 ± 2.989, which was significantly decreased from the score of 6.923 ± 2.280 prior to brachytherapy. Skin hyperpigmentation, mucositis, and dysphagia were the most frequently reported adverse events. ConclusionsBrachytherapy as a sole modality, was retrospectively proven effective and safe in the management of inoperable SGCs and was beneficial in multiple irradiation and pain control.