A survey of diffuse interstellar bands in the Andromeda galaxy: optical spectroscopy of M31 OB stars

We present the largest sample to-date of intermediate-resolution blue-to-red optical spectra of B-type supergiants in M31 and undertake the first survey of diffuse interstellar bands (DIBs) in this galaxy. Spectral classifications, radial velocities and interstellar reddenings are presented for 34 stars in three regions of M31. Radial velocities and equivalent widths are given for the 5780 and 6283 DIBs towards 11 stars. Equivalent widths are also presented for the following DIBs detected in three sightlines in M31: 4428, 5705, 5780, 5797, 6203, 6269, 6283, 6379, 6613, 6660, and 6993. All of these M31 DIB carriers reside in clouds at radial velocities matching those of interstellar Na I and/or H I. The relationships between DIB equivalent widths and reddening (E(B-V)) are consistent with those observed in the local ISM of the Milky Way. Many of the observed sightlines show DIB strengths (per unit reddening) which lie at the upper end of the range of Galactic values. DIB strengths per unit reddening are found (with 68% confidence), to correlate with the interstellar UV radiation field strength. The strongest DIBs are observed where the interstellar UV flux is lowest. The mean Spitzer 8/24 micron emission ratio in our three fields is slightly lower than that measured in the Milky Way, but we identify no correlation between this ratio and the DIB strengths in M31. Interstellar oxygen abundances derived from the spectra of three M31 H II regions in one of the fields indicate that the average metallicity of the ISM in that region is 12 + log[O/H] = 8.54 +- 0.18, which is approximately equal to the value in the solar neighbourhood

Current status of graft choice in adults for anterior cruciate ligament reconstruction: a systematic review and meta-analysis

The anterior cruciate ligament (ACL) is a frequently performed surgical procedure in the field of sports medicine, and graft selection is an essential aspect of ACL reconstruction (ACLR) that has been shown to optimize post-operative rehabilitation, facilitate return to full sporting function and reduce the risk of complications. However, there needs to be more agreement regarding optimal graft choice. The present study aims to identify the optimal graft choice in the adult population undergoing ACLR. The current systematic review explores the electronic database of online libraries of academic institutions from 2011 to 30 September 2022 and compared the clinical outcomes of autograft and allograft for ACLR, which provides an evidence-based approach for graft selection. The findings of our present study delineate that ACLR in adult populations with autograft is the most promising choice for ligament tear over allograft based on lower failure rate, reduced complications, and high cost-effectiveness. However, there was no significant difference in overall IKDC, pivot shift, Lachman test, and Tegner activity. This critical analysis recommends that for an adult population, ACLR with autograft can provide better clinical results than an allograft, but further studies carried out about other parameters affecting the long-term stability, quick return, and physical therapy adopted outside the supervision of the respective surgeon would be required

The Three-Dimensional Structure of Interior Ejecta in Cassiopeia A at High Spectral Resolution

We used the Spitzer Space Telescope's Infrared Spectrograph to create a high resolution spectral map of the central region of the Cassiopeia A supernova remnant, allowing us to make a Doppler reconstruction of its 3D structure. The ejecta responsible for this emission have not yet encountered the remnant's reverse shock or the circumstellar medium, making it an ideal laboratory for exploring the dynamics of the supernova explosion itself. We observe that the O, Si, and S ejecta can form both sheet-like structures as well as filaments. Si and O, which come from different nucleosynthetic layers of the star, are observed to be coincident in velocity space in some regions, and separated by 500 km/s or more in others. Ejecta traveling toward us are, on average, ~900 km/s slower than the material traveling away from us. We compare our observations to recent supernova explosion models and find that no single model can simultaneously reproduce all the observed features. However, models of different supernova explosions can collectively produce the observed geometries and structures of the interior emission. We use the results from the models to address the conditions during the supernova explosion, concentrating on asymmetries in the shock structure. We also predict that the back surface of Cassiopeia A will begin brightening in ~30 years, and the front surface in ~100 years.Comment: 35 pages, 16 figures, accepted to Ap

Systematic Evaluation of Skeletal Mechanical Function

Many genetic and environmental perturbations lead to measurable changes in bone morphology, matrix composition, and matrix organization. Here, straightforward biomechanical methods are described that can be used to determine whether a genetic or environmental perturbation affects bone strength. A systematic method is described for evaluating how bone strength is altered in the context of morphology and tissue‐level mechanical properties, which are determined in large part from matrix composition, matrix organization, and porosity. The methods described include computed tomography, whole‐bone mechanical tests (bending and compression), tissue‐level mechanical tests, and determination of ash content, water content, and bone density. This strategy is intended as a first step toward screening mice for phenotypic effects on bone and establishing the associated biomechanical mechanism by which function has been altered, and can be conducted without a background in engineering. The outcome of these analyses generally provides insight into the next set of experiments required to further connect cellular perturbation with functional change. Curr. Protoc. Mouse Biol. 3:39‐67 © 2013 by John Wiley & Sons, Inc.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143805/1/cpmo130027.pd

Noninfectious retrovirus particles drive the APOBEC3/Rfv3 dependent neutralizing antibody response.

Members of the APOBEC3 family of deoxycytidine deaminases counteract a broad range of retroviruses in vitro through an indirect mechanism that requires virion incorporation and inhibition of reverse transcription and/or hypermutation of minus strand transcripts in the next target cell. The selective advantage to the host of this indirect restriction mechanism remains unclear, but valuable insights may be gained by studying APOBEC3 function in vivo. Apobec3 was previously shown to encode Rfv3, a classical resistance gene that controls the recovery of mice from pathogenic Friend retrovirus (FV) infection by promoting a more potent neutralizing antibody (NAb) response. The underlying mechanism does not involve a direct effect of Apobec3 on B cell function. Here we show that while Apobec3 decreased titers of infectious virus during acute FV infection, plasma viral RNA loads were maintained, indicating substantial release of noninfectious particles in vivo. The lack of plasma virion infectivity was associated with a significant post-entry block during early reverse transcription rather than G-to-A hypermutation. The Apobec3-dependent NAb response correlated with IgG binding titers against native, but not detergent-lysed virions. These findings indicate that innate Apobec3 restriction promotes NAb responses by maintaining high concentrations of virions with native B cell epitopes, but in the context of low virion infectivity. Finally, Apobec3 restriction was found to be saturable in vivo, since increasing FV inoculum doses resulted in decreased Apobec3 inhibition. By analogy, maximizing the release of noninfectious particles by modulating APOBEC3 expression may improve humoral immunity against pathogenic human retroviral infections

Mathematical Reflections: Standing on the Shoulders of Giants

The layperson\u27s response to mathematics is often that of desperation. When we tell people our occupation, do we more often than not hear about their unpleasant experiences with mathematics. They often tell us, I studied algebra in high school and haven\u27t used it since! Indeed, that may be true. However, we can reply, How many times has algebra been used on you? We are all restricted, and protected, by the formulas of mathematics. In the mysterious metaphors we have agreed to cal mathematics, all creation is involved, from the symbol-happy logician down to the cunning geometers, the bees. When I trust myself to a ladder, I lean upon mathematics. Every baby is a formula-baby, for when we say that its growth is a function of its nourishment, what are we citing but a case of calculus? There are no nonmathematical minds, but only nonmathematical teachers. The masses who draw back in fear at the sound of the word mathematics are often merely suffering from a bad persistent case of early pedagogy. I believe one of the first steps in motivating the unmotivated is in getting them to realize that We, the teachers, are NOT the enemy

The Three-Dimensional Structure of Cassiopeia A

We used the Spitzer Space Telescope's Infrared Spectrograph to map nearly the entire extent of Cassiopeia A between 5-40 micron. Using infrared and Chandra X-ray Doppler velocity measurements, along with the locations of optical ejecta beyond the forward shock, we constructed a 3-D model of the remnant. The structure of Cas A can be characterized into a spherical component, a tilted thick disk, and multiple ejecta jets/pistons and optical fast-moving knots all populating the thick disk plane. The Bright Ring in Cas A identifies the intersection between the thick plane/pistons and a roughly spherical reverse shock. The ejecta pistons indicate a radial velocity gradient in the explosion. Some ejecta pistons are bipolar with oppositely-directed flows about the expansion center while some ejecta pistons show no such symmetry. Some ejecta pistons appear to maintain the integrity of the nuclear burning layers while others appear to have punched through the outer layers. The ejecta pistons indicate a radial velocity gradient in the explosion. In 3-D, the Fe jet in the southeast occupies a "hole" in the Si-group emission and does not represent "overturning", as previously thought. Although interaction with the circumstellar medium affects the detailed appearance of the remnant and may affect the visibility of the southeast Fe jet, the bulk of the symmetries and asymmetries in Cas A are intrinsic to the explosion.Comment: Accepted to ApJ. 54 pages, 21 figures. For high resolution figures and associated mpeg movie and 3D PDF files, see http://homepages.spa.umn.edu/~tdelaney/pape