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

Opioids depress cortical centers responsible for the volitional control of respiration

Respiratory depression limits provision of safe opioid analgesia and is the main cause of death in drug addicts. Although opioids are known to inhibit brainstem respiratory activity, their effects on cortical areas that mediate respiration are less well understood. Here, functional magnetic resonance imaging was used to examine how brainstem and cortical activity related to a short breath hold is modulated by the opioid remifentanil. We hypothesized that remifentanil would differentially depress brain areas that mediate sensory-affective components of respiration over those that mediate volitional motor control. Quantitative measures of cerebral blood flow were used to control for hypercapnia-induced changes in blood oxygen level-dependent (BOLD) signal. Awareness of respiration, reflected by an urge-to-breathe score, was profoundly reduced with remifentanil. Urge to breathe was associated with activity in the bilateral insula, frontal operculum, and secondary somatosensory cortex. Localized remifentanil-induced decreases in breath hold-related activity were observed in the left anterior insula and operculum. We also observed remifentanil-induced decreases in the BOLD response to breath holding in the left dorsolateral prefrontal cortex, anterior cingulate, the cerebellum, and periaqueductal gray, brain areas that mediate task performance. Activity in areas mediating motor control (putamen, motor cortex) and sensory-motor integration (supramarginal gyrus) were unaffected by remifentanil. Breath hold-related activity was observed in the medulla. These findings highlight the importance of higher cortical centers in providing contextual awareness of respiration that leads to appropriate modulation of respiratory control. Opioids have profound effects on the cortical centers that control breathing, which potentiates their actions in the brainstem

Contribution of maternal effects to dietary selection in Mediterranean fruit flies

Individual responses to dietary variation represent a fundamental component of fitness, and nutritional adaptation can occur over just a few generations. Maternal effects can show marked proximate responses to nutrition, but whether they contribute to longer term dietary adaptation is unclear. Here, we tested the hypotheses that maternal effects: (i) contribute to dietary adaptation, (ii) diminish when dietary conditions are constant between generations, (iii) are trait-specific and (iv) interact with high- and low-quality food. We used experimental evolution regimes in the medfly (Ceratitis capitata) to test these predictions by subjecting an outbred laboratory-adapted population to replicated experimental evolution on either constant high calorie sugar (‘A’) or low-calorie starch (‘S’) larval diets, with a standard adult diet across both regimes. We measured the contribution of maternal effects by comparing developmental and adult phenotypes of individuals reared on their own diet with those swapped onto the opposite diet for either one or two generations (high and low maternal effect conditions, respectively), both at the start and after 30 generations of selection. Initially, there were strong maternal effects on female body mass and male mating success but not larval survival. Interestingly, the initial maternal effects observed in female body mass and male mating success showed sex-specific interactions when individuals from high calorie regimes were tested on low calorie diets. However, as populations responded to selection, the effects of maternal provisioning on all traits diminished. The results broadly supported the predictions. They show how the contribution of maternal effects to dietary responses evolves in a context-dependent manner, with significant variation across different fitness-related traits. We conclude that maternal effects can evolve during nutritional adaptation and hence may be an important life history trait to measure, rather than to routinely minimize

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

CNI-1493 inhibits monocyte/macrophage tumor necrosis factor by suppression of translation efficiency

Tumor necrosis factor (TNF) mediates a wide variety of disease states including septic shock, acute and chronic inflammation, and cachexia. Recently, a multivalent guanylhydrazone (CNI-1493) developed as an inhibitor of macrophage activation was shown to suppress TNF production and protect against tissue inflammation and endotoxin lethality [Bianchi, M., Ulrich, P., Bloom, O., Meistrell, M., Zimmerman, G. A., Schmidtmayerova, H., Bukrinsky, M., Donnelley, T., Bucala, R., Sherry, B., Manogue, K. R., Tortolani, A. J., Cerami, A. & Tracey, K. J. (1995) Mol. Med. 1, 254-266, and Bianchi, M., Bloom, O., Raabe, T., Cohen, P. S., Chesney, J., Sherry, B., Schmidtmayerova, H., Zhang, X., Bukrinsky, M., Ulrich, P., Cerami, A. & Tracey, J. (1996) J. Exp. Med., in press]. We have now elucidated the mechanism by which CNI-1493 inhibits macrophage TNF synthesis and show here that it acts through suppression of TNF translation efficiency. CNI-1493 blocked neither the lipopolysaccharide (LPS)-induced increases in the expression of TNF mRNA nor the translocation of nuclear factor NF-kappa B to the nucleus in macrophages activated by 15 min of LPS stimulation, indicating that CNI-1493 does not interfere with early NF-kappa B-mediated transcriptional regulation of TNF. However, synthesis of the 26-kDa membrane form of TNF was effectively blocked by CNI-1493. Further evidence for the translational suppression of TNF is given by experiments using chloram-phenicol acetyltransferase (CAT) constructs containing elements of the TNF gene that are involved in TNF translational regulation. Both the 5' and 3' untranslated regions of the TNF gene were required to elicit maximal translational suppression by CNI-1493. Identification of the molecular target through which CNI-1493 inhibits TNF translation should provide insight into the regulation of macrophage activation and mechanisms of inflammation

Correction to: Exploring the biological functional mechanism of the HMGB1/TLR4/MD-2 complex by surface plasmon resonance.

After publication of this article (He et al., 2018), the corresponding authors recognised an error in Scheme 1, in particular to section A. HMGB1/TLR4/MD-2 complex formation . Above Step 2: B box binding to MD-2 , the text incorrectly read: Low affinity / extremely slow off . In addition, some text was omitted below TLR4/MD-2 . The correct version of Scheme 1 is included in this Correction article. The original article (He et al., 2018) has been corrected

Student Employment Models for Undergraduate Nurses and Midwives in Australia: A Scoping Review

Introduction: Evidence has shown that throughout their undergraduate years, many nursing and midwifery students obtain paid employment in a wide variety of clinical and non-clinical positions. Across Australia, inconsistencies exist in the models of clinical employment available to these student groups. Previous Australian studies have described the employment of undergraduate nursing and midwifery students in regulated and unregulated clinical roles. No studies have reported on the various regulated roles available to both student nurses and midwives in Australia. The purpose of this scoping review is to identify and synthesize evidence related to nursing and/or midwifery students employed in regulated and unregulated clinical roles in Australia. Methods: This scoping review utilized published recommendations for data screening, abstraction, and synthesis. One of the authors, a librarian, undertook systematic searches in CINAHL Complete (1937–present), Emcare on Ovid (1995–present), Scopus (1969–present), and Ovid MEDLINE(R) (including Epub Ahead of Print, In-Process, and In-Data-Review & Other Non-Indexed Citations, 1946–present). The initial searches were completed in April 2019 and repeated in March 2021 and May 2022 to identify any new literature. Manual searching of reference lists in the included papers was also undertaken, together with selected organizational websites. The extracted data included the lead author, date, title, study design, study sample and location, and key findings. Results: From the 53 items retrieved, 23 peer-reviewed studies met the inclusion criteria and were included in the review. All items were published between 2011 and 2022. Only four of the studies focused upon student midwives. Undergraduate nursing and midwifery students in Australia obtain paid employment in a variety of regulated and unregulated clinical roles. Conclusion: The literature reported here demonstrates that there are differing models, nomenclature, educational requirements, and pay scales in place for student employment in clinical roles across Australian states and territories

Study of direct versus orbital entry for Mars missions. Volume 6 - Appendix D - Subsystem studies and parametric data Final report

Subsystems analyses and parametric data on configurations for direct versus orbital entry for Mars mission