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Almost 60 years after the assassination of President John F. Kennedy in 1963, the majority of Americans are still reluctant to believe official reports presented by the commissions gathered in 1964 and again in 1976 that determined the direction of the shot resulting in the fatal head injury. Long-withheld, confidential government files released in 2017 reignited the controversy. The present investigation computationally simulated projectile-skull-impacts from the direction specified in official reports and from three other directions. Detailed geometric models of the human head and ammunition, as well as known parameters from the assassination site served as the supportive base for analysis. Constitutive mathematical models for the impact of projectile material with skull tissues at supersonic speed were employed to analyze bone and bullet fragmentation mechanics. Simulated fracture characteristics of bone and bullet were compared with photographic and X-ray evidence. The most likely origin of the fatal shot was determined based on the degree of corresponding deformation and fragmentation between simulation and documented evidence. Computational corroboration could be established as physically consistent with high-speed impact from the rear, as established by the official commissions. Simulations of three other speculative shot origins did not correspond with the documented evidence. •Finite element simulation applied to fatal cranial gunshot to president Kennedy.•Simulation compares speculative shot origins to skull fracture and bullet evidence.•Match to evidence achieved by simulated shot from Texas School Book Depository.•Due to mismatch with evidence other speculative shot origins are excluded.

High-resolution time-lapse ground-penetrating radar (GPR) observations of advancing and retreating water tables can yield a wealth of information about near-surface water content dynamics. In this study, we present and analyze a series of imbibition, drainage and infiltration experiments that have been carried out at our artificial ASSESS test site and observed with surface-based GPR. The test site features a complicated but known subsurface architecture constructed with three different kinds of sand. It allows the study of soil water dynamics with GPR under a wide range of different conditions. Here, we assess in particular (i) the feasibility of monitoring the dynamic shape of the capillary fringe reflection and (ii) the relative precision of monitoring soil water dynamics averaged over the whole vertical extent by evaluating the bottom reflection. The phenomenology of the GPR response of a dynamically changing capillary fringe is developed from a soil physical point of view. We then explain experimentally observed phenomena based on numerical simulations of both the water content dynamics and the expected GPR response.

Osteosarcoma is the most common primary malignant bone tumor with a strong tendency to metastasize, limiting the prognosis of affected patients. Genomic, epigenomic and transcriptomic analyses have demonstrated the exquisite molecular complexity of this tumor, but have not sufficiently defined the underlying mechanisms or identified promising therapeutic targets. To systematically explore RNA-protein interactions relevant to OS, we define the RNA interactomes together with the full proteome and the transcriptome of cells from five malignant bone tumors (four osteosarcomata and one malignant giant cell tumor of the bone) and from normal mesenchymal stem cells and osteoblasts. These analyses uncover both systematic changes of the RNA-binding activities of defined RNA-binding proteins common to all osteosarcomata and individual alterations that are observed in only a subset of tumors. Functional analyses reveal a particular vulnerability of these tumors to translation inhibition and a positive feedback loop involving the RBP IGF2BP3 and the transcription factor Myc which affects cellular translation and OS cell viability. Our results thus provide insight into potentially clinically relevant RNA-binding protein-dependent mechanisms of osteosarcoma. Proteomic, transcriptomic, and genomic analysis has shown osteosarcoma (OS) to be a complex and heterogenous disease but revealed little about its carcinogenesis or potential therapeutic targets. Here, the authors profile the RNA interactome, transcriptome and proteome of cells derived from OS patients, identifying a targetable vulnerability to translation inhibition.

Hard evidence Gamma-ray bursts (GRBs) are either ‘long and soft’, or ‘short and hard’. It is now clear that the long-duration type are caused by explosions of massive stars in distant star-forming galaxies. Only in recent months, with the Swift satellite latching onto bursts as soon as they happen, has it been possible to collect data on short bursts that may lead to similar certainty as to their cause. GRB 050724 burst onto the scene on 24 July, and has all the properties needed to solve the mystery of short GRBs. The new evidence supports the merging compact object model of short GRBs, involving either a neutron star–neutron star merger, or a neutron star–black hole binary system as progenitor. Despite a rich phenomenology, γ-ray bursts (GRBs) are divided 1 into two classes based on their duration and spectral hardness—the long-soft and the short-hard bursts. The discovery of afterglow emission from long GRBs was a watershed event, pinpointing 2 their origin to star-forming galaxies, and hence the death of massive stars, and indicating 3 an energy release of about 10 51  erg. While theoretical arguments 4 suggest that short GRBs are produced in the coalescence of binary compact objects (neutron stars or black holes), the progenitors, energetics and environments of these events remain elusive despite recent 5 , 6 , 7 , 8 localizations. Here we report the discovery of the first radio afterglow from the short burst GRB 050724, which unambiguously associates it with an elliptical galaxy at a redshift 9 z = 0.257. We show that the burst is powered by the same relativistic fireball mechanism as long GRBs, with the ejecta possibly collimated in jets, but that the total energy release is 10–1,000 times smaller. More importantly, the nature of the host galaxy demonstrates that short GRBs arise from an old (> 1 Gyr) stellar population, strengthening earlier suggestions 5 , 6 and providing support for coalescing compact object binaries as the progenitors.

We present a method to rapidly identify hydrogen-mediated interactions in proteins (e.g., hydrogen bonds, hydrogen bonds, water-mediated hydrogen bonds, salt bridges, and aromatic π-hydrogen interactions) through heavy atom geometry alone, that is, without needing to explicitly determine hydrogen atom positions using either experimental or theoretical methods. By including specific real (or virtual) partner atoms as defined by the atom type of both the donor and acceptor heavy atoms, a set of unique angles can be rapidly calculated. By comparing the distance between the donor and the acceptor and these unique angles to the statistical preferences observed in the Protein Data Bank (PDB), we were able to identify a set of conserved geometries (15 for donor atoms and 7 for acceptor atoms) for hydrogen-mediated interactions in proteins. This set of identified interactions includes every polar atom type present in the Protein Data Bank except OE1 (glutamate/glutamine sidechain) and a clear geometric preference for the methionine sulfur atom (SD) to act as a hydrogen bond acceptor. This method could be readily applied to protein design efforts.

Background Most medical responders are not adequately trained to recognize and treat maternal medical emergencies, including maternal cardiac arrest, and national credentialing standards do not exist. Obstetric Life Support (OBLS) is a validated simulation-based curriculum designed to equip prehospital and hospital-based healthcare workers (HCWs) with the knowledge and skills necessary to prevent, recognize, and manage maternal medical emergencies. Widespread implementation of OBLS could enhance patient safety and reduce disparities in maternal morbidity and mortality. However, research is needed to develop strategies that ensure sustained and equitable access for HCWs across diverse healthcare settings. This paper presents a protocol for evaluating a train-the-trainer approach to implement OBLS in hospitals, freestanding birthing centers, and prehospital contexts across Arizona. Methods This multisite, mixed-methods study is being conducted in collaboration with the Arizona Perinatal Trust, a regional perinatal health system that encompasses 38 in-hospital birthing centers and Level I-IV hospitals across Arizona, and the Arizona Emergency Medical Systems LLC, which coordinates 85 emergency medical services agencies statewide. A Steering Committee comprising local, regional, and national stakeholders provides guidance and oversight for all study activities. To promote rapid learning, two consecutive OBLS implementation and evaluation cycles will be conducted, with the second cycle incorporating feedback and lessons learned from the first. HCWs from 16 implementation sites (8 per cycle) serving areas with high maternal vulnerability indexes will be trained as OBLS instructors. These instructors will train at least 160 HCWs (80 per cycle) within their respective or nearby institutions. Outcomes to be assessed include reach (proportion and representation of institutions offering OBLS, instructors trained, and HCWs participating), effectiveness (impact of OBLS on knowledge and clinical competencies, presence of code carts containing OBLS cognitive aids and resuscitative cesarean delivery kits in hospitals, and the use of an OB Arrest Alert in prehospital settings), adoption (allocation of resources for OBLS), implementation (number of courses completed, fidelity of the training delivery), and maintenance (extent to which training becomes integrated into routine practice and policy). Discussion Findings from this statewide study will be used to promote the scale-up and sustainability of OBLS, ultimately enhancing maternal healthcare quality and equity.

Aquatic ecosystems are exposed to pesticides through various pathways such as spray-drift, agricultural runoff, and chemical spills. Understanding the impact of pesticides on freshwater ecosystems requires not only understanding how pesticides affect aquatic organisms but also knowledge of their interactions with other stressors, such as those related to global climate change. Heatwaves are extended periods of temperature increase relative to the climatological mean. They are increasing in frequency and magnitude and pose an emerging threat to shallow freshwater ecosystems. In this study, we evaluated the single and combined effects of the herbicide terbuthylazine and a simulated heatwave on freshwater zooplankton communities using indoor microcosms. Terbuthylazine was applied at an environmentally relevant concentration (15 µg/L). The heatwave consisted of an increase of 6°C above the control temperature for a period of 7 days. When applied individually, the heatwave increased the total abundance of zooplankton by 3 times. The terbuthylazine exposure led to an indirect effect on the zooplankton community structure, reducing the relative abundance of some taxa. The combination of the heatwave and terbuthylazine had no significant impact on the zooplankton community, indicating additive effects dominated by the herbicide. The interaction between the two stressors increased chlorophyll-a concentrations and apparently changed the structure of the phytoplankton community, which may have benefitted cyanobacteria over green algae. Overall, this study shows that understanding the effects of chemical and non-chemical stressors on aquatic communities remains a challenging task. Further studies should be conducted to improve our mechanistic understanding of multiple stressor interactions at different levels of biological organisation.

The final chapter in the long-standing mystery of the γ-ray bursts (GRBs) centres on the origin of the short-hard class of bursts, which are suspected on theoretical grounds to result from the coalescence of neutron-star or black-hole binary systems. Numerous searches for the afterglows of short-hard bursts have been made, galvanized by the revolution in our understanding of long-duration GRBs that followed the discovery in 1997 of their broadband (X-ray, optical and radio) afterglow emission. Here we present the discovery of the X-ray afterglow of a short-hard burst, GRB 050709, whose accurate position allows us to associate it unambiguously with a star-forming galaxy at redshift z = 0.160, and whose optical lightcurve definitively excludes a supernova association. Together with results from three other recent short-hard bursts, this suggests that short-hard bursts release much less energy than the long-duration GRBs. Models requiring young stellar populations, such as magnetars and collapsars, are ruled out, while coalescing degenerate binaries remain the most promising progenitor candidates. Short gamma-ray bursts Gamma-ray bursts (GRBs) are either ‘long and soft’, or ‘short and hard’. The long-duration type leave a strong afterglow and have been extensively studied. So we have a good idea of what causes them: explosions of massive stars in distant star-forming galaxies. Short GRBs, with no strong afterglow, were harder to pin down. The Swift satellite, launched last November, is designed to study bursts as soon as they happen. Having shown its worth with long GRBs (reported in the 18 August issue of Nature ), Swift has now bagged a short burst, GRB 050509B, precisely measured its location and detected the X-ray afterglow. Four papers this week report on this and another recent short burst. Now, over 20 years after they were first recognized, the likely origin of the short GRBs is revealed as a merger between neutron stars of a binary system and the instantaneous production of a black hole.

Both the shape of individual particles and their surface properties contribute to the strength of a granular material under shear. Here we show the degree to which these two aspects can be intertwined. In experiments on assemblies of 3D printed, convex lens-shaped particles, we measure the stress–strain response under repeated compressive loading and find that the aggregate’s shear strength falls rapidly when compared to other particle shapes. We probe the granular material at mm-scales with X-ray computed tomography and \\[\\upmu \\]m-scales with high-resolution surface metrology to look for the cause of the degradation. We find that wear due to accumulated deformation smooths out the lens surfaces in a controlled and systematic manner that correlates with a significant loss of shear strength observed for the assembly as a whole. The sensitivity of lenses to changes in surface properties contrasts with results for assemblies of 3D printed tetrahedra and spheres, which under the same load cycling are found to exhibit only minor degradation in strength. This case study provides insight into the relationship between particle shape, surface wear, and the overall material response, and suggests new strategies when designing a granular material with desired evolution of properties under repeated deformation.