333 research outputs found
Propagation of highly nonlinear signals in a two dimensional network of granular chains
We report the first experimental observation of highly nonlinear signals propagating in a two dimensional system composed of granular chains. In this system one of the chains contacts two others to allow splitting and redirecting the solitary-like signal formed in the first chain. The system consists of a double Y-shaped guide in which high- and low-modulus chains of spheres are arranged in various geometries. We observed fast splitting of the initial pulse, rapid chaotization of the signal and sharp bending of the propagating acoustic information. Pulse and energy trapping was also observed in composite systems assembled from hard- and soft-particles in the branches
Implications of Shock Wave Experiments with Precompressed Materials for Giant Planet Interiors
This work uses density functional molecular dynamics simulations of fluid
helium at high pressure to examine how shock wave experiments with
precompressed samples can help characterizing the interior of giant planets. In
particular, we analyze how large of a precompression is needed to probe a
certain depth in a planet's gas envelope. We find that precompressions of up to
0.1, 1.0, 10, or 100 GPa are needed to characterized 2.5, 5.9, 18, to 63% of
Jupiter's envelope by mass.Comment: Submitted As Proceedings Article For The American Physical Society
Meeting On Shock Compression Of Condensed Matter, Hawaii, June, 200
Predicting C-H/ interactions with nonlocal density functional theory
We examine the performance of a recently developed nonlocal density
functional in predicting a model noncovalent interaction, the weak bond between
an aromatic system and an aliphatic C-H group. The new functional is a
significant improvement over traditional density functionals, providing results
which compare favorably to high-level quantum-chemistry techniques but at
considerably lower computational cost. Interaction energies in several model
C-H/ systems are in generally good agreement with coupled-cluster
calculations, though equilibrium distances are consistently overpredicted when
using the revPBE functional for exchange. The new functional correctly predicts
changes in energy upon addition of halogen substituents.Comment: 5 pages, 4 figure
Pet Care System
Contemporary society requires the average adult to juggle multiple tasks and commitments. These commitments are occasionally neglected as there is simply not enough time available in the day. Taking care of oneâs pets is one example of a neglected responsibility; Pioneer Solutions has realized this difficulty that pet owners face. The solution that has been proposed, and that is currently being designed, is a system that will allow the owner to assure the well being of their pet via a website. The userâfriendly website will allow the owner to monitor, feed, and exercise their pet without physically being at the residence
Simulation of Particle Size Effect on Dynamic Properties and Fracture of PTFE-W-Al Composites
Recent investigations of the dynamic compressive strength of cold
isostatically pressed composites of polytetrafluoroethylene (PTFE), tungsten
(W) and aluminum (Al) powders show significant differences depending on the
size of metallic particles. The addition of W increases the density and overall
strength of the sample. To investigate relatively large deformations
multi-material Eulerian and arbitrary Lagrangian-Eulerian methods, which have
the ability to efficiently handle the formation of free surfaces, were used.
The calculations indicate that the increased strength of the sample with fine
metallic particles is due to the formation of force chains under dynamic
loading. This phenomenon occurs even at larger porosity of the PTFE matrix in
comparison with samples with larger particle size of W and higher density of
the PTFE matrix.Comment: 5 pages, 6 figure
Molybdenum sound velocity and shear modulus softening under shock compression
We measured the longitudinal sound velocity in Mo shock compressed up to 4.4 Mbars on the Hugoniot. Its sound speed increases linearly with pressure up to 2.6 Mbars; the slope then decreases up to the melting pressure of âŒ3.8 Mbars. This suggests a decrease of shear modulus before the melt. A linear extrapolation of our data to 1 bar agrees with the ambient sound speed. The results suggest that Mo remains in the bcc phase on the Hugoniot up to the melting pressure. There is no statistically significant evidence for a previously reported bccâhcp phase transition on the Hugoniot
Tantalum sound velocity under shock compression
We used several variations of the shock compression method to measure the longitudinal sound velocity of shocked tantalum over the pressure range 37â363âGPa with a typical uncertainty of 1.0%%. These data are consistent with Ta remaining in the bcc phase along the principal Hugoniot from ambient pressure to â300âGPa, at which pressure melting occurs. These data also do not support the putative melting phenomena reported below 100âGPa in some static compression experiments
Reply to âComment on âMolybdenum sound velocity and shear modulus softening under shock compressionâ â
We respond to the Comment by Errandonea et al. [Phys. Rev. B 92, 026101 (2015)] on their reinterpretation of our published data [Nguyen et al., Phys. Rev. B 89, 174109 (2014)]. In the original paper, we argued that there is no solid-solid phase transition along the Hugoniot at 2.1 Mbars. There is, however, a softening of the shear modulus starting at 2.6 Mbars. Errandonea et al. [Phys. Rev. B 92, 026101 (2015)] reinterpreted our data and concluded that there is a structural change near 2.3 Mbars on the Hugoniot. We will explore the differences and agreements in the two interpretations of our data
Tantalum sound velocity under shock compression
We used several variations of the shock compression method to measure the longitudinal sound velocity of shocked tantalum over the pressure range 37â363âGPa with a typical uncertainty of 1.0%%. These data are consistent with Ta remaining in the bcc phase along the principal Hugoniot from ambient pressure to â300âGPa, at which pressure melting occurs. These data also do not support the putative melting phenomena reported below 100âGPa in some static compression experiments
Real world, multicentre patterns of treatment and survival in metastatic renal cell carcinoma with the UK Renal Oncology Collaborative ( UK ROC ): Is it time to look favourably on firstâline immunotherapy containing combinations in all IMDC groups?
Introduction: Clinical trials show improved progressionâfree survival (PFS) and overall survival (OS) in firstâline metastatic renal cell carcinoma (mRCC) patients with immunotherapy containing systemic antiâcancer therapies (SACT). However, in the favourable international metastatic renal cell cancer database consortium (IMDC) group there is no trial evidence for OS benefit despite clear PFS improvement when comparing antiâVEGF tyrosine kinase inhibitor (TKI) monotherapy and (immunotherapy and TKI) IO/TKI combinations. Objective: To assess the impact of firstâline SACT choice on the clinical outcomes of PFS and OS in mRCC. To evaluate this impact of initial SACT for allcomers and the favourable IMDC group. Methods: A multicentre retrospective review of patients who started SACT for mRCC (01/01/2018â30/06/2021) at 17 UK NHS trusts. Patient demographics and IMDC group were analysed. Survival data were compared using KaplanâMeier curves, and the statistical significance of differences in outcome between the groups was assessed with the logârank test. Univariable and multivariable Cox proportional hazard modelling estimate the hazard ratios (HRs) for survival outcomes associated with IMDC and treatment subtype. Results: One thousand three hundred and nineteen patients were identified with a median age of 64. 294 (22.3%), 695 (52.7%) and 321 (24.3%) were IMDC group favourable, intermediate and poor, respectively. 311 (23.6%), 197 (14.9%) and 778 (59%) patients received checkpoint inhibitor and antiâCTLA4 monoclonal antibody (IO/IO), IO/TKI and TKI firstâline SACT across all IMDC groups. Significant PFS improvement favouring IO/TKI versus TKI was demonstrated in allcomers HR = 0.61. In the favourable risk group, Log rank testing demonstrated a significant benefit for IO/TKI over TKI for PFS (HR = 0.60, 95% CI [0.39, 0.91]) and OS (HR = 0.42, 95% CI [0.18, 0.99]). Conclusion: In this realâworld evidence cohort, we have shown OS and PFS benefit with IO/TKI versus TKI in the favourable IMDC risk group. This has not been previously reported from trial outcomes and would support use of frontâline IO/TKI in mRCC favourable risk patients
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