Soft Band Research Articles

X-ray metal line emission from the hot circumgalactic medium: probing the effects of supermassive black hole feedback

ABSTRACT We derive predictions from state-of-the-art cosmological galaxy simulations for the spatial distribution of the hot circumgalactic medium (CGM, [0.1–1]R200c) through its emission lines in the X-ray soft band ([0.3–1.3] keV). In particular, we compare IllustrisTNG, EAGLE, and SIMBA and focus on galaxies with stellar mass $10^{10-11.6}\, \rm {M}_{\odot }$ at z = 0. The three simulation models return significantly different surface brightness radial profiles of prominent emission lines from ionized metals such as O vii(f), O viii, and Fe xvii as a function of galaxy mass. Likewise, the three simulations predict varying azimuthal distributions of line emission with respect to the galactic stellar planes, with IllustrisTNG predicting the strongest angular modulation of CGM physical properties at radial range ${{\gtrsim}0.3{-}0.5\, R_{200c}}$. This anisotropic signal is more prominent for higher energy lines, where it can manifest as X-ray eROSITA-like bubbles. Despite different models of stellar and supermassive black hole (SMBH) feedback, the three simulations consistently predict a dichotomy between star-forming and quiescent galaxies at the Milky Way and Andromeda mass range, where the former are X-ray brighter than the latter. This is a signature of SMBH-driven outflows, which are responsible for quenching star formation. Finally, we explore the prospect of testing these predictions with a microcalorimeter-based X-ray mission concept with a large field of view. Such a mission would probe the extended hot CGM via soft X-ray line emission, determine the physical properties of the CGM, including temperature, from the measurement of line ratios, and provide critical constraints on the efficiency and impact of SMBH feedback on the CGM.

Abundance and temperature of the outer hot circumgalactic medium

Context. Despite their vital importance to understanding galaxy evolution and our own Galactic ecosystem, our knowledge of the physical properties of the hot X-ray emitting phase of the Milky Way is still inadequate. However, sensitive SRG/eROSITA large area surveys are now providing us with the long-sought data needed to mend this state of affairs. Aims. Our aim is to constrain the properties of the Milky Way hot halo emission toward intermediate Galactic latitudes close to the Galactic anti-center. Methods. We analyzed the spectral properties of the integrated soft X-ray emission observed by eROSITA in the relatively deep eFEDS field. Results. We observe a flux of 12.6 and 5.1 × 10−12 erg cm−2 s−1 deg−2 in the total (0.3–2) and soft (0.3–0.6 keV) band. We measure the temperature and metal (oxygen) abundance of the hot circumgalactic medium (CGM) to be within kTCGM = 0.153–0.178 keV and ZCGM = 0.052–0.072 Z⊙, depending on the contribution of solar wind charge exchange (SWCX). Slightly higher CGM abundances ZCGM = 0.05–0.10 Z⊙ are possible, considering the uncertain extrapolation of the extragalactic cosmic X-ray background (CXB) emission below ~1 keV. To recover CGM abundances as high as ZCGM = 0.3 Z⊙, the presence of an additional component must be postulated, likely associated with the warm-hot intergalactic medium, providing ~15–20% of the flux in the soft X-ray band. We observe line widths of the CGM plasma smaller than Δυ ≤ 500 km s−1. The emission in the soft band is dominated (~47%) by the circumgalactic medium (CGM), whose contribution reduces to ~30% if heliospheric SWCX contributes at the level of ~15% also during solar minimum. The remaining flux is provided by the CXB (~33%) and the local hot bubble (~18%). Moreover, the eROSITA data require the presence of an additional component associated with the elusive Galactic corona plus a possible contribution from unresolved M dwarf stars. This component has a temperature of kT ~ 0.4– 0.7 keV, a considerable (~ kiloparsec) scale height, and might be out of thermal equilibrium. It contributes ~9% to the total emission in the 0.6—2 keV band, and is therefore a likely candidate to produce part of the unresolved CXB flux observed in X-ray ultra-deep fields. We also observe a significant contribution to the soft X-ray flux due to SWCX, during periods characterized by stronger solar wind activity, and causing the largest uncertainty on the determination of the CGM temperature. Conclusions. We constrain temperature, emission measure, abundances, thermal state, and spectral shape of the outer hot CGM of the Milky Way.

Investigation of the Electronic Structure of the Mg<sub>99.2</sub>Zn<sub>0.2</sub>Y<sub>0.6</sub> Alloy Using X-ray Photoelectron Spectroscopy

We investigated the electronic structure of the Mg99.2Zn0.2Y0.6 alloy using hard and soft X-ray photoemission spectroscopy and electronic band structure calculations to understand the mechanism of the phase stability of this material. Electronic structure of the Mg99.2Zn0.2Y0.6 alloy showed a semi-metallic electronic structure with a pseudo-gap at the Fermi level. The observed electronic structure of the Mg99.2Zn0.2Y0.6 alloy suggests that the presence of a pseudogap structure is responsible for phase stability.

Revealing the intrinsic X-ray reverberation lags in IRAS 13224−3809 through the Granger causality test

ABSTRACT The Granger causality is an econometric test for determining whether one time series is useful for forecasting another one with a certain Granger lag. Here, the light curves in the 0.3–1 keV (reflection dominated, soft) and 1.2–5 keV (continuum dominated, hard) bands of active galactic nuclei are produced, and the Granger lags are estimated and compared to the traditional lag–frequency spectra. We find that the light curves in the hard band Granger-cause (lead) those in the soft band, whereas the obtained Granger lags could be interpreted as the intrinsic reverberation lags. Then, we extract the Granger-lag profiles from 14 XMM–Newton observations of IRAS 13224−3809, and find that the lags are significant in 12 observations. The majority of the obtained Granger (intrinsic) lags are ∼200–500 s. With the IRAS 13224−3809 mass of 2 × 106 M⊙, these lags correspond to the true light travel distance of ∼20–50 rg. Hence, by assuming a lamp-post geometry and a face-on disc, this places the corona at ∼10–25 rg above the central black hole. Moreover, multiple Granger lags consisting of the small and large lags of <500 s and >1000 s are detected in four observations. This means that the corona height can significantly evolve from ∼10–25 rg to ∼55rg, or vice versa, towards the end of the observation. Granger lags are a promising way to measure the intrinsic lags, and provide evidence of coronal height variability within each individual observation.

EFFECT OF MOLECULAR ENVIRONMENT ON PROTEIN RUBBER PROPERTIES

ABSTRACTMany natural organisms use “protein rubbers” to store and release an imposed strain energy with high efficiency to make motion easier. Protein rubbers exist in a complicated environment surrounded by water and other molecules such as sugars, implying that amino acid composition and its environment are important in protein rubber behavior. Gelatin, the hydrolysis product of animal collagen, is hydrated or “plasticized” with water, ethylene glycol, glycerol, corn syrup, and aqueous solutions of sorbitol, glucose, and fructose. The rubber formed is “dry”, that is, is not fully immersed in liquid, and has the appearance and feel of a soft rubber band. The mechanical and thermodynamic behavior of each rubber is characterized with low strain dynamic and high strain tensile experiments with good agreement between the two. Plasticized gelatin rubbers are incompressible and follow the neo-Hookean model for rubber elasticity up to moderate extension ratios. Higher molecular weight polyols with more hydrogen bond donors and acceptors create gelatin networks with lower crosslink density. Ethylene glycol–, glycerol-, sorbitol syrup–, and fructose syrup–plasticized gelatin rubbers have similar molecular relaxation mechanisms and are the most efficient rubbers when probed in the rubbery plateau region prior to approaching the glass transition. The other plasticizers have different molecular relaxation mechanisms that detract from the efficiency of energy storage and return that is not related to network formation but perhaps the individual solvation ability of each plasticizer.

Influence of soft band on seismic slope stability by finite-element limit-analysis modelling

Soft bands may widely exist in sites, and their presence complicates the analysis of slope stability, particularly when the limit analysis method is adopted. Note that the use of the limit analysis method is capable of providing rigorous lower and upper bound solutions and hence is widely used in soil slope stability analyses. To account for soft band effects, finite-element lower-bound (FELB) and finite-element upper-bound (FEUB) approaches are introduced in this study. Finite element discretization aids in the construction of a statically allowable stress field and kinematically admissible velocity field, which are prerequisites for limit analysis. In combination with a modified pseudodynamic approach, seismic slope stability analysis is evaluated through linear programming. Lower and upper bound solutions of the slope safety factor (FoS) are optimized with an interior point algorithm, which aids in better estimating the true FoS of seismic slope stability. The nonassociated flow rule is also discussed herein. After validating the upper and lower linear programming models by limit equilibrium and FEM, the soft band’s effects on seismic slope stability are discussed, and a rotational-translational failure mechanism is revealed by critical velocity fields. A less than 5.1% difference between lower- and upper-bound solutions is favourable for providing a reliable reference for slope design.

The IXPE View of GRB 221009A

We present the IXPE observation of GRB 221009A, which includes upper limits on the linear polarization degree of both prompt and afterglow emission in the soft X-ray energy band. GRB 221009A is an exceptionally bright gamma-ray burst (GRB) that reached Earth on 2022 October 9 after traveling through the dust of the Milky Way. The Imaging X-ray Polarimetry Explorer (IXPE) pointed at GRB 221009A on October 11 to observe, for the first time, the 2–8 keV X-ray polarization of a GRB afterglow. We set an upper limit to the polarization degree of the afterglow emission of 13.8% at a 99% confidence level. This result provides constraints on the jet opening angle and the viewing angle of the GRB, or alternatively, other properties of the emission region. Additionally, IXPE captured halo-rings of dust-scattered photons that are echoes of the GRB prompt emission. The 99% confidence level upper limit to the prompt polarization degree depends on the background model assumption, and it ranges between ∼55% and ∼82%. This single IXPE pointing provides both the first assessment of X-ray polarization of a GRB afterglow and the first GRB study with polarization observations of both the prompt and afterglow phases.

Confirmation of two magnetic cataclysmic variables as polars: 1RXS J174320.1−042953 and YY Sex

ABSTRACTWe present our analysis of new and archived observations of two candidate magnetic cataclysmic variables, namely 1RXS J174320.1−042953 and YY Sex. 1RXS J174320.1−042953 was observed in two distinctive high and low states where a phase shift was seen, which could be due to changes in the shape, size, and (or) location of the accretion region. We find that its orbital X-ray modulations only persist in the soft (0.3–2.0 keV) energy band, which could be attributed to photoelectric absorption in the accretion flow. The X-ray spectra exhibit a multi-temperature post-shock region where the hard X-rays are absorbed through a thick absorber with an equivalent hydrogen column of ∼7.5 × 1023 cm−2, which partially covers ∼56 per cent of the emission. No soft X-ray excess was found to be present; however, a soft X-ray emission with a blackbody temperature of ∼97 eV describes the spectra. Extensive Transiting Exoplanet Survey Satellite (TESS) observations of YY Sex allow us to refine its orbital period to 1.5746 ± 0.0011 h. We did not find any signature of previously reported spin or beat periods in this system. Furthermore, our new polarimetric observations show clear circular polarization modulated on the orbital period only. Finally, both systems show strong Balmer and He ii 4686 Å emission lines in the optical spectra, further indicative of their magnetic nature.

The 100-month Swift catalogue of supergiant fast X–ray transients

Supergiant fast X-ray transients (SFXTs) are high mass X-ray binaries (HMXBs) displaying X-ray outbursts that can reach peak luminosities up to 1038 erg s−1 and spend most of their lives in more quiescent states with luminosities as low as 1032−1033 erg s−1. During the quiescent states, less luminous flares are also frequently observed with luminosities of 1034−1035 erg s−1. The main goal of the comprehensive and uniform analysis of the SFXT Swift triggers presented in this paper is to provide tools to predict whether a transient that has no known X-ray counterpart may be an SFXT candidate. These tools can be exploited for the development of future missions exploring the variable X-ray sky through large field-of-view instruments. We examined all available data on outbursts of SFXTs that triggered the Swift/Burst Alert Telescope (BAT) collected between 2005 August 30 and 2014 December 31, in particular those for which broad-band data, including the Swift/X-ray Telescope (XRT) data, are also available. This work complements and extends our previous catalogue of SFXT flares detected by BAT from 2005 February 12 to 2013 May 31, since we now include the additional BAT triggers recorded until the end of 2014 (i.e. beyond the formal first 100 months of the Swift mission). Due to a change in the mission’s observational strategy, virtually no SFXT triggers obtained a broad-band response after 2014. We processed all BAT and XRT data uniformly by using the Swift Burst Analyser to produce spectral evolution dependent flux light curves for each outburst in the sample. The BAT data allowed us to infer useful diagnostics to set SFXT triggers apart from the general γ-ray burst population, showing that SFXTs uniquely give rise to image triggers and are simultaneously very long, faint, and ‘soft’ hard-X-ray transients. We find that the BAT data alone can discriminate very well the SFXTs from other classes of fast transients, such as anomalous X-ray pulsars and soft gamma repeaters. On the contrary, the XRT data collected around the time of the BAT triggers are shown to be decisive for distinguishing SFXTs from, for instance, accreting millisecond X-ray pulsars and jetted tidal disruption events. The XRT observations of 35 (out of 52 in total) SFXT BAT triggers show that in the soft X-ray energy band, SFXTs display a decay in flux from the peak of the outburst of at least three orders of magnitude within a day and rarely undergo large re-brightening episodes, favouring in most cases a rapid decay down to the quiescent level within three to five days (at most).

Critical role of magnetic moments in the lattice dynamics of YBa2Cu3O6

The role of lattice dynamics in unconventional high-temperature superconductivity is still vigorously debated. Theoretical insights into this problem have long been prevented by the absence of an accurate first-principles description of the combined electronic, magnetic, and lattice degrees of freedom. Utilizing the recently constructed ${\mathrm{r}}^{2}$SCAN density functional that stabilizes the antiferromagnetic (AFM) state of the pristine oxide ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{6}$, we faithfully reproduce the experimental dispersion of key phonon modes. We further find significant magnetoelastic coupling in numerous high-energy Cu-O bond stretching optical branches, where the AFM results improve over the soft nonmagnetic phonon bands.

A rapid optical and X-ray timing study of the neutron star X-ray binary Swift J1858.6−0814

ABSTRACT We present a rapid timing analysis of optical (HiPERCAM and ULTRACAM) and X-ray (NICER) observations of the X-ray transient Swift J1858.6−0814 during 2018 and 2019. The optical light curves show relatively slow, large amplitude (∼1 mag in gs) ‘blue’ flares (i.e. stronger at shorter wavelengths) on time-scales of ∼minutes as well as fast, small amplitude (∼0.1 mag in gs) ‘red’ flares (i.e. stronger at longer wavelengths) on time-scales of ∼seconds. The ‘blue’ and ‘red’ flares are consistent with X-ray reprocessing and optically thin synchrotron emission, respectively, similar to what is observed in other X-ray binaries. The simultaneous optical versus soft- and hard-band X-ray light curves show time- and energy-dependent correlations. The 2019 March 4 and parts of the June data show a nearly symmetric positive cross-correlations (CCFs) at positive lags consistent with simple X-ray disc reprocessing. The soft- and hard-band CCFs are similar and can be reproduced if disc reprocessing dominates in the optical and one component (disc or synchrotron Comptonization) dominates both the soft and hard X-rays. A part of the 2019 June data shows a very different CCFs. The observed positive correlation at negative lag in the soft band can be reproduced if the optical synchrotron emission is correlated with the hot flow X-ray emission. The observed timing properties are in qualitative agreement with the hybrid inner hot accretion flow model, where the relative role of the different X-ray and optical components that vary during the course of the outburst, as well as on shorter time-scales, govern the shape of the optical/X-ray CCFs.

Bone Anchored Hearing Aid: A Narrative Review

Bone Anchored Hearing Aid (BAHA) is a small vibrator that can be reversibly attached to a Titanium (Ti) screw and implanted behind the ear. It uses the bone conduction channel to activate the cochleae by converting sound into the vibration of the screw. The two main indications are conductive hearing loss and unilateral deafness when using traditional hearing aids is not possible, as a rehabilitative or mixed hearing loss with a moderate perceptual component. For patients with canal atresia, Single-sided Deafness (SSD), and chronically discharged ears despite treatment, the BAHA implant is an option. Combination hearing loss is a crucial indicator for implanted hearing implants. Various options are accessible based on the bone conduction threshold. Patients with modest sensorineural impairment usually benefit from transcutaneous Bone Conduction Implants (BCI), while those with intermediate hearing loss may also benefit from percutaneous BCI devices. For combined, active middle ear implants are advised for hearing deficits with moderate and severe cochlear hearing loss. For individuals who need middle ear surgery or who are incompatible with other options for therapy, implants are a helpful and successful addition. Skin-drive Bone Conduction Devices (BCDs) are BCDs that vibrate the bone via the skin can also be separated into passive subcutaneous devices and traditional devices that are coupled, for instance, with soft bands with implanted magnets. BCDs that directly stimulate the bone, percutaneous devices, and dynamic transcutaneous devices are examples of direct-drive devices. The latter kind of apparatus uses embedded transducers to stimulate bone effectively via healthy skin. The BAHA, also known as the percutaneous direct-drive device (BCD), now rules the market. More direct-drive and skin-drive transcutaneous solutions are now being studied, partly due to problems with the transdermal implant and partly for aesthetic reasons.

Prevalence of Simonart's band in cleft children at a cleft center in Indonesia: A nine-year retrospective study.

Simonart's band is a soft tissue band that connects the cleft gap of the base of the nostril or the margin of the alveolus. While research on the prevalence of Simonart's band in cleft lip and palate cases has been carried out in various countries, research on Simonart's band in Indonesia has yet to be conducted. This study aimed to determine the prevalence of different types of Simonart's band at a cleft center in Indonesia. The data of cleft patients were reviewed retrospectively over a 9-year period at the Cleft Lip and Palate Center Center, Harapan Kita Women and Children Hospital, Jakarta, Indonesia. The patients were divided based on the type of cleft and the type of Simonart's band. The results were analyzed by means of descriptive statistics. Out of 638 cleft patients from the period 2008-2016, 77 patients had Simonart's band. The liptolip band was most commonly found (52 cases, 67.5%). The lip-to-alveolus band was found in 20 cases (26.0%) and the alveolus-to-alveolus band had the lowest prevalence of 5 cases (6.5%). Associations between the cleft type (unilateral cleft lip and palate (UCLP), unilateral cleft lip and alveolus (UCLA), and bilateral cleft lip and palate (BCLP)) and Simonart's band type were all significant (p = 0.001, according to Fisher's exact test), which indicates significant differences in the distribution of the bands with regard to different cleft types. There was a significant difference in the distribution of the bands between the UCLP and UCLA groups (p = 0.000). On the other hand, the distribution of the bands in the UCLP group did not differ much from that in the BCLP group (p = 0.065). The prevalence of Simonart's band was significantly higher in the patients with the unilateral complete cleft of the primary and secondary palate than in the subjects with the cleft of the primary palate. In the UCLP group, most patients had the lip-to-lip band type. In the BCLP group, the majority also had the lip-to-lip band type. In contrast, in the UCLA group, the majority showed the lip-to-alveolus band type.

Study of X-Ray Intraday Variability of HBL Blazars Based on Observations Obtained with XMM-Newton

We present an extensive study on the X-ray intraday variability of 10 teraelectronvolt-emitting high synchrotron peaked blazars (HBLs): 1ES 0229+200, 1ES 0414+009, PKS 0548-322, 1ES 1101-232, 1H 1219+301, H 1426+428, Mrk 501, 1ES 1959+650, PKS 2005-489, and 1ES 2344+514 made with 25 XMM-Newton pointed observations during its operational period. Intraday variability has been estimated in three energy bands: soft (0.3–2 keV), hard (2–10 keV), and total (0.3–10 keV). Although seven out of 10 teraelectronvolt HBLs exhibited some intraday variability at 3σ levels, no major variations exceeding 6% were detected. We explored the spectral properties of the sample by extracting the hardness ratio from the soft and hard bands; no significant variations in the hardness ratio were observed in any source. We performed power spectral density analyses on the variable light curves by fitting power laws, yielding slopes lying in the range of 1.11–2.93 for different HBLs. We briefly discuss possible emission mechanisms and carry out rough estimates for magnetic fields, electron Lorentz factors, and emission region sizes for seven of these HBLs.

X-ray spectral and timing analysis of the Compton Thick Seyfert 2 galaxy NGC 1068

ABSTRACT We present the timing and spectral analysis of the Compton Thick Seyfert 2 active galactic nuclei NGC 1068 observed using NuSTAR and XMM–Newton. In this work for the first time we calculated the coronal temperature ($\rm {kT_{e}}$) of the source and checked for its variation between the epochs if any. The data analysed in this work comprised of (a) eight epochs of observations with NuSTAR carried out during the period 2012 December to 2017 November, and, (b) six epochs of observations with XMM–fNewton carried out during 2000 July to 2015 February. From timing analysis of the NuSTAR observations, we found tfhe source not to show any variations in the soft band. However, on examination of the flux at energies beyond 20 keV, during 2014 August and 2017 August the source was brighter by about 20 and 30 per cent, respectively, compared to the mean flux of the three 2012 NuSTAR observations as in agreement with earlier results in literature. From an analysis of XMM–Newton data we found no variation in the hard band (2–4 keV) between epochs as well as within epochs. In the soft band (0.2–2 keV), while the source was found to be not variable within epochs, it was found to be brighter in epoch B relative to epoch A. By fitting physical models we determined $\rm {kT_{e}}$ to range between 8.46$^{+0.39}_{-0.66}$ and 9.13$^{+0.63}_{-0.98}$ keV. From our analysis, we conclude that we found no variation of $\rm {kT_{e}}$ in the source.

Anticorrelated lags in a neutron star Z source GX 5-1: AstroSat’s View

ABSTRACT We report the cross-correlation function studies of a neutron star low-mass X-ray binary, a Z source GX 5-1, using Soft X-ray Telescope (SXT) and Large Area X-ray Proportional Counter (LAXPC) energy bands onboard AstroSat. For the first time, we report the lag between soft (0.8–2.0 keV, SXT) and hard X-ray energy bands (10–20 and 16–40 keV, LAXPC) in GX 5-1 and detected lags of the order of a few tens to hundreds of seconds in the horizontal branch. We interpreted them as the readjustment time-scale of the inner region of the accretion disc. We used various two components and three-component spectral models to unfold the spectra and observed the changes in soft and hard component fluxes that were exhibiting horizontal branch oscillation variations. It was observed that the bbody component assumed to be originating from the boundary layer over the NS and was also found to vary along with the HBO variation where lags were detected. We constrained the size of the comptonizing region of the order 15–55 km, assuming that lags were due to variation in the size of the corona. We noticed a similar size of the comptonizing region after employing other models and suggest that the overall size of corona must be of the order of a few tens of km to explain the lags, HBO variation, and respective spectral variations. In a case study, it was noted that the BL size increases as GX 5-1 vary from the top of the HB to the upper vertex.

Two-gap superconductivity in a Janus MoSH monolayer

Hydrides under ultrahigh pressure, such as ${\mathrm{H}}_{3}\mathrm{S}$ and ${\mathrm{LaH}}_{10}$, can achieve coveted superconducting critical temperatures via the conventional electron-phonon coupling mechanism. In this work, we report first-principles investigation of high-temperature phonon-mediated superconductivity in a two-dimensional metal hydride, namely, the Janus MoSH monolayer. The MoSH sheet is a recently synthesized intermediate in realizing Janus transition metal dichalcogenides by involving stripping the top-layer S of ${\mathrm{MoS}}_{2}$ with H atoms [X. Wan et al., ACS Nano 15, 20319 (2021); A. Y. Lu et al., Nat. Nanotechnol. 12, 744 (2017)]. We find coupling of electrons from $\mathrm{Mo}\text{\ensuremath{-}}d$ orbitals around the Fermi level to ultrahigh frequency H- and S-derived phonons, analogous to superconducting hydrides of ${\mathrm{H}}_{3}\mathrm{S}$ and ${\mathrm{LaH}}_{10}$. This leads to strong coupling two-gap superconductivity with the calculated critical temperature ${T}_{c}$ being about 28.58 K at atmosphere pressure. The presence of soft phonon bands from the Mo in-plane vibrations, in cooperation with the electron susceptibility, accounts for the strong electron-phonon coupling of the MoSH monolayer. By further aligning the Fermi level via doping, the ${T}_{c}$ can be boosted to 37.31 K, close to the McMillan limit (39 K). Thus, our work points out a real metal hydride for the realization of two-dimensional high-temperature superconductivity at atmosphere pressure and facilitates further studies on new families of Janus transition-metal sulfhydrates.

Post-operative Wound Care Protocol Prevents Surgical Site Infection After Craniotomy

<h3>Background</h3> Surgical Site Infections (SSIs) following craniotomy may be affected by extensive head vasculature. Attentive post-operative wound care to keep hair away, cleanse skin, and remove incisional clots that provide nutrients for organisms may help prevent SSIs. <h3>Methods</h3> In 2018, 72% of craniotomy SSIs at an academic medical center were related to post-operative wound disruption, drainage, and compromised wound healing. These SSIs involved Gram-positive organisms, consistent with skin flora. In January 2019, a post-operative wound care protocol developed by neurosurgical nurse and wound care specialists, and the infection prevention program was initiated, involving 1) soft bands to keep the incision clear of hair, and 2) 2% chlorhexidine gluconate (CHG) cloths to clean the incision and the proximal 6-inches of any drains, remove incisional clots, and clean adjacent skin and hair within 2 inches of the incision. Twice-weekly photos were taken of post-operative craniotomy wounds with protocol lapses and real-time feedback was provided to the bedside nurse, wound care nurse, and surgeon from February 2019-February 2020. Due to the Coronavirus Disease 2019 pandemic (COVID-19), the program progressively lapsed until January 2021, when it was reinstated. SSI rates were compared during the periods with and without the intervention using a chi-square test. <h3>Results</h3> Baseline Craniotomy SSI rate prior to January 2019 was 3.8% (5/133, SIR=2.6) and 1.7% (16/952, SIR=1.1) during the first intervention period. During COVID-19 surge, SSIs increased to 3.6% (5/140, SIR=2.3) without the intervention, and were restored to a lower rate, 1.6% (2/128, SIR=0.9) after the intervention was reinstituted. SSI rates were lower in intervention (1.7% (18/1080)) versus non-intervention periods (3.7% (10/273)), p=0.04. <h3>Conclusions</h3> A post-operative inpatient craniotomy wound care protocol involving hair care, incisional CHG cleansing and clot removal, plus photo documentation and feedback for protocol adherence was associated with SSI reduction.

Perspectives of the LOBSTER-EYE monitor in the soft X-ray observing the Galactic center region

We show the lobster-eye (LE) monitor's perspectives and observing plan based on a small LE telescope on a small (CubeSat-like) satellite platform. This instrument is important because it is able to provide wide-field X-ray imaging. We present the possibilities of monitoring the Galactic center region in the soft X-ray energy band. The reason is that many X-ray binaries, especially those with a low-mass lobe-filling secondary and mostly the neutron star accretor, concentrate in the bulge surrounding the center of our Galaxy. Several such binaries are expected to be present in our monitor's field of view (a square of about 5×5degrees). We show the long-term activity of the examples of X-ray binaries located in this region. We present the typical features of such objects' long-term X-ray activity (e.g., outbursts and state transitions) and discuss how the lobster-eye monitor can contribute. Observing in the soft X-ray band is the most promising because their X-ray intensity is the highest in this band.

The Diffuse X-Ray Background of the Insight-HXMT/LE Telescope in the Galactic Plane

Accurately estimating of diffuse X-ray background (DXB) is essential for the investigation of sources in the Galactic plane observed with Insight-HXMT/LE, which is a collimated telescope in the soft X-ray energy band with a relatively large field of view. In the high-Galactic-latitude region, DXB is dominated by the cosmic X-ray background, which is almost uniform, but DXB in the Galactic plane region is more complex due to the Galactic H i absorption and the contribution of the Galactic ridge X-ray emission. This study, as a part of background estimation of LE, focuses on estimating the contribution of DXB in the Galactic plane to Insight-HXMT/LE observations. We calculate DXB confined in a region of 0° < l < 360° and ∣b∣ < 10°, where l and b denote Galactic longitude and latitude, respectively, with the first 3 yr of Galactic-plane-scanning survey data of Insight-HXMT/LE. The Galactic plane is divided into 360 × 20 small pixels (1° × 1° per pixel), and a DXB spectrum is obtained for each pixel. An indirect method is developed for the pixels of the bright source regions, which brings a systematic error of ∼10%. The systematic error brought by the satellite attitude is ∼7% on average for all the pixels in the Galactic plane. The LE DXB spectrum obtained in this study is consistent with that reported by RXTE’s Proportional Counter Array.