Mesoscale shock structure in particulate composites

Multiscale experiments in heterogeneous materials and the knowledge of their physics under shock compression are limited. This study examines the multiscale shock response of particulate composites comprised of soda-lime glass particles in a PMMA matrix using full-field high-speed digital image correlation (DIC) for the first time. Normal plate impact experiments, and complementary numerical simulations, are conducted at stresses ranging from $1.1-3.1$ GPa to elucidate the mesoscale mechanisms responsible for the distinct shock structure observed in particulate composites. The particle velocity from the macroscopic measurement at continuum scale shows a relatively smooth velocity profile, with shock thickness decreasing with an increase in shock stress, and the composite exhibits strain rate scaling as the second power of the shock stress. In contrast, the mesoscopic response was highly heterogeneous, which led to a rough shock front and the formation of a train of weak shocks traveling at different velocities. Additionally, the normal shock was seen to diffuse the momentum in the transverse direction, affecting the shock rise and the rounding-off observed at the continuum scale measurements. The numerical simulations indicate that the reflections at the interfaces, wave scattering, and interference of these reflected waves are the primary mechanisms for the observed rough shock fronts

Strength of magnesium at high pressures and strain rates

The strength and deformation mechanisms in magnesium can be significantly affected by anisotropy, high strain rates, and pressure. In this study, pressure shear plate impact (PSPI) experiments are conducted to measure the strength of extruded polycrystalline magnesium at pressures varying from 5 to 10 GPa at a nominal strain rate of 10⁵ s⁻¹. The experimental technique enables to first shock load the material sample to the desired normal stress in one direction, and then shear the material in a perpendicular direction. A recently developed hybrid analysis method for PSPI experiments is used to extract the stress–strain curves of magnesium from the particle velocity records measured at the rear surface of the target. The PSPI experimental results reveal a slower twinning saturation at high pressures. To better understand the material behavior under the combined stress states in the PSPI experiments, the results were compared with that of a specimen deformed by a two-step process of quasi-static compression followed by dynamic shear loading at relatively low pressure. The two-stage loading at low pressure, and the calculation of temperature rise in the PSPI experiment revealed that the combined effect of the reorientation and the temperature rise lower the flow strength of magnesium at high pressures under multiaxial loading

Lessons Learnt from Operationalising an International Collaborative Multi-Centre Study

Many medical students are both skilled and experienced in healthcare research, statistical analysis and evidence synthesis; assets that can be deployed to great effect in order to conduct research and contribute to the body of evidence - particularly in outbreak situations where senior doctors may be redeployed to clinical duties, thus ensuring that the next generation of academic clinicians’ interest and knowledge does not go in vain. Here, we document the process by which a group of medical students across the world, with senior support, harnessed their enthusiasm and the power of technology to play leading roles in an international multi-centre study run by the Global Health Research Group on Children’s Non-Communicable Diseases (Global Children’s NCDs). Many lessons have been learnt from the successful operationalisation of this study, which we hope to impart in this article. Our operations team consisted of: a social media team who manage our various accounts; a graphic design team who produce visuals to illustrate milestones achieved or highlight countries from which we did not yet have representatives; a network team who constructed a database to manage our extensive collaborator network; a communications team who managed emails and maintained regular contact with collaborators as well as producing a guide of common issues; a researcher support team who worked to ensure that any issues faced were dealt with promptly by hosting drop-in sessions; and finally a research capacity building team. We found that medical students bring fresh perspectives and an open-minded approach which is useful in reframing challenges and generating innovative solutions; thus it is vital to give them the opportunity to collaborate with, and learn from senior academics and policy-makers.&nbsp

Primary Posterior Sagittal Anorectoplasty in male neonates with Anorectal Malformations: A tertiary care hospital experience

Background: The conventional surgical management for a male neonate with intermediate Anorectal Malformation (ARM) involves three stages – the creation of a diversion stoma in the neonatal period, a definitive pull-through procedure/ Posterior Sagittal Anorectoplasty (PSARP) followed by stoma closure. With this background, we present our experience with Single-stage primary definitive repair in selected male neonates with ARM. Methods: Medical records of male ARM cases managed from 2016 to 2018 were reviewed. Male neonates who underwent primary PSARP were analysed retrospectively. Results: A total of 35 records were found, out of which 12 male neonates underwent primary PSARP. The      median gestational age and birth weight were 36.7 weeks and 2.75 kg respectively. Fistula with urinary tract was documented in all. The mean operative time was      65 minutes +/- 15 minutes. Two neonates had minor superficial surgical site infection at neo-anus. Anal dilatations were started after 2 weeks. At follow-up period of 3 years, 11 patients were continent; one patient had constipation with pseudo-incontinence which was successfully being managed by bowel management programme. Conclusions: A primary definitive procedure is feasible when performed on carefully selected male neonates with ARM and also avoids the morbidity of stoma and multiple surgeries and follow-up visits to hospitals

BLOOM: A 176B-Parameter Open-Access Multilingual Language Model

Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License

An investigation of shock-induced phase transition in soda-lime glass

There exists a large body of evidence from experiments and molecular dynamics simulations to suggest the occurrence of phase transitions in soda-lime glass (SLG) and other silica glasses subject to shock compression to pressures above 3 GPa. In light of these findings, the current work investigated the existence of phase transition in SLG using shock and release experiments. The experiments employed symmetric SLG-SLG impact to achieve complete unloading to zero stress after shock compression to stresses in the range of 3-7 GPa. The stress-strain response and the Lagrangian release wave speed behavior of SLG obtained from these experiments are seen to reveal a mismatch between the loading and unloading paths of the pressure-strain curve for the material, which serves as compelling evidence for the occurrence of a shock-induced phase transition in the material at relatively low pressures. Furthermore, the release wave speed vs strain data obtained from experiments were used to construct a methodology for modeling the shock and release behavior of SLG. This scheme implemented in numerical simulations was able to capture the release behavior of shock compressed SLG, for which a robust and satisfactory model was previously unavailable.</p

Page 98

Measurement of strength at high pressures is critical to understanding the behavior of materials subjected to extreme loading conditions. Recent developments have extended the pressure shear plate impact (PSPI) technique to the high-pressure regime. Such experiments provide a unique opportunity to extract the complete stress–strain behavior of materials at relatively high pressures. The modified technique includes a new fiber-optic heterodyne transverse velocity interferometer system and new analysis methods to account for the inelastic response of the anvil plates. In this study, PSPI experiments are conducted on oxygen-free high conductivity (OFHC) copper at pressures ranging from 10 to 43 GPa and at strain rates of ~ 10⁵ s⁻¹. Complete stress–strain curves of copper are obtained using a hybrid methodology that relies on numerical simulations and particle velocity records gathered in these experiments. Experiments are conducted at similar pressures and strain rates using two types of anvils that undergo different levels of plastic strains: tool steel and tungsten carbide, to check the robustness of the hybrid method. The behavior of copper at these high pressures and strain rates is compared with previous literature data, and the effect of pressure and strain rate on the strength behavior of copper are discussed. It was observed that the rate of change in yield strength with pressure was 2.5 times the rate of change of shear modulus with pressure. The strength models that predict the response of copper at these extreme conditions are also examined and validated

Effectiveness of device-based therapy for conservative management of low back pain

U Republici Hrvatskoj susrećemo se s procesom ubrzanog starenja stanovništva. Sustav socijalne skrbi potrebno je prilagoditi potrebama starijeg stanovništva koje se neprestano mijenjaju i povećavaju. Stariji ljudi susreću se s tipičnim posljedicama starenja, no i s pojavom poteškoća i bolesti koje su češće u starijoj životnoj dobi. Standardi suvremene gerontologije usmjeravaju se na poboljšanje kvalitete života osoba starije dobi i njihove aktivnosti, a ne samo na brigu o tjelesnom zdravlju. Mentalno zdravlje definirano je kao stanje potpunog tjelesnog, mentalnog i društvenog blagostanja, a ne samo odsutnost bolesti ili slabosti. Muzikoterapija i općenito uključivanje u muzičke aktivnosti, posebice za osobe koje su na trajnom smještaju u domovima za starije osobe, može uvelike pomoći u održavanju i poboljšanju njihovog mentalnog zdravlja. U ovom istraživanju ispitivan je učinak muzikoterapije na mentalno zdravlje osoba starije životne dobi koje su smještene u domovima za starije osobe. U istraživanju je sudjelovalo 26 sudionika, korisnika doma za starije osobe, koji su bili podvrgnuti muzikoterapijskom tretmanu u trajanju od 12 seansi prije i poslije kojeg su mjereni aspekti mentalnog zdravlja poput depresivnosti i anksioznosti, percipiranog stresa te subjektivnog blagostanja. Rezultati su pokazali da postoji značajan učinak muzikoterapije na smanjenje simptoma depresivnosti, anksioznosti i percipiranog stresa te povećanje subjektivnog blagostanja kod osoba starije životne dobi.In the Republic of Croatia, we are facing a process of accelerated aging of the population. The social welfare system needs to be tailored to the needs of older people which are constantly changing and increasing. Elderly people are faceing with the typical effects of aging, but also with the onset of difficulties and diseases that are more common in older ages. The standards of modern gerontology focus on improving the quality of life of older people and their activity, not just on their physical health. Mental health is defined as the state of complete physical, mental and social well-being, not just the absence of disease or weakness. Music therapy and in general engageing in music activities, especially for people who are in residences for older people, can greatly assist in maintaining and improving the mental health of the elderly. In this study, the effects of music therapy on the mental health of elderly persons housed in homes for the elderly was studied. 26 participants, elderly home users, were subjected to a music therapy treatment lasting 12 sessions before and after which mental health aspects such as depression, anxiety, perceived stress and subjective well-being were measured. The results have shown that there is a significant effect of music therapy on reducing symptoms of depression and anxiety, reducing perceived stress and increasing subjective well-being in the elderly

Low-grade fibromyxoid sarcoma in a child presenting as a popliteal fossa swelling

Popliteal fossa masses are rare in paediatric age group. Even rarer are the malignancies of this area. Low-grade fibromyxoid sarcoma (LGFMS) is a distinctive variant of fibrosarcoma. It is a rare tumor with benign histologic appearance but high metastasizing potential. We describe an 11-year-old child with a popliteal fossa mass, which was excised, and histopathological report revealed LGFMS