Anisotropic constitutive relationships in energetic materials: PETN and HMX

This paper presents results of first-principles density functional calculations of the equation of state (EOS) of PETN-I and beta-HMX. The isotropic EOS for hydrostatic compression has been extended to include uniaxial compressions in the [100], [010], [001], [110], [101], [011], and [111] directions up to compression ratio V/V0 = 0.70. Equilibrium properties, including lattice parameters and elastic constants, as well as hydrostatic EOS are in good agreement with available experimental data. The shear stresses of uniaxially compressed PETN-I and beta-HMX have been evaluated and their behavior as a function of compression ratio has been used to make predictions of shock sensitivity of these EMs. A comparison of predicted sensitivities with available experimental data has also been performed

First-principles anisotropic constitutive relationships in β-cyclotetramethylene tetranitramine (β-HMX)

First-principles density functional theory calculations have been performed to obtain constitutive relationships in the crystalline energetic material β-cyclotetramethylene tetranitramine (β-HMX). In addition to hydrostatic loading, uniaxial compressions in the directions normal to the {100}, {010}, {001}, {110}, {101}, {011}, and {111} planes have been performed to investigate the anisotropic equation of state (EOS). The calculated lattice parameters and hydrostatic EOS are in reasonable agreement with the available experimental data. The uniaxial compression data show a significant anisotropy in the principal stresses, change in energy, band gap, and shear stresses, which might lead to the anisotropy of the elastic-plastic shock transition and shock sensitivity of β-HMX

First-principles investigation of anisotropic constitutive relationships in pentaerythritol tetranitrate

First-principles density functional theory (DFT) calculations have been used to obtain the constitutive relationships of pentaerythritol tetranitrate (PETN-I), a crystalline energetic material. The isotropic equation of state (EOS) for hydrostatic compression has been extended to include uniaxial compressions in the , , , , , , and crystallographic directions up to a compression ratio of V/V0=0.70. DFT predicts equilibrium properties such as lattice parameters and elastic constants, as well as the hydrostatic EOS, in agreement with available experimental data. Our results show a substantial anisotropy of various properties of PETN-I upon uniaxial compression. To characterize the anisotropic traits of PETN, different physical properties of the uniaxially compressed crystal such as the energy per atom, band gap, and stress tensor have been evaluated as a function of compression ratio. The maximum shear stresses were calculated and examined for a correlation with the anisotropy in shock-initiation sensitivity

Density functional theory calculations of anisotropic constitutive relationships in alpha-cyclotrimethylenetrinitramine

Constitutive relationships in the crystalline energetic material alpha-cyclotrimethylenetrinitramine (alpha-RDX) have been investigated using first-principles density functional theory. The equilibrium properties of alpha-RDX including unit cell parameters and bulk modulus, as well as the hydrostatic equation of state (EOS), have been obtained and compared with available experimental data. The isotropic EOS has been extended to include the anisotropic response of alpha-RDX by performing uniaxial compressions normal to several low-index planes, {100}, {010}, {001}, {110}, {101}, {011}, and {111}, in the Pbca space group. The uniaxial-compression data exhibit a considerable anisotropy in the principal stresses, changes in energy, band gaps, and shear stresses, which might play a role in the anisotropic behavior of alpha-RDX under shock loading

Having burned the straw man of Christian spiritual leadership, what can we learn from Jesus about leading ethically?

In considering what it means to lead organizations effectively and ethically the literature comprising spirituality at work (SAW) and spiritual leadership theory (SLT) has become highly influential, especially in the USA. It has also attracted significant criticism. While, in this paper we endorse this critique, we argue that that the strand of literature which purportedly takes a Christian standpoint within the wider SAW school of thought, largely misconstrues and misapplies the teaching of its founder, Jesus. As a result, in dismissing the claims and application of SAW and SLT, there is a real risk that we lose the vital contribution of Christian thought, not least some of the timeless counter-cultural wisdom of Jesus which, we contend, offers a vital foundation to the practice of ethical leadership and business ethics in organisations. In proposing a way forward, two thorny issues which face all leaders are addressed: dealing with ego and closing the gap between what we say and what we do. The more we understand about the dynamics of human nature, the more we learn about the profundity of Jesus’ teachings. We then propose a number of ways in which Jesus-centred ethical leadership can be practised. Each is radical and each implies risk: both the personal risk of inner renewal arising from repentance as a doorway to personal integrity, as well as the risk of opposing unethical practices and promoting the excellence of core practices in the workplace

Modeling Luminosity-Dependent Galaxy Clustering Through Cosmic Time

We employ high-resolution dissipationless simulations of the concordance LCDM cosmology to model the observed luminosity dependence and evolution of galaxy clustering through most of the age of the universe, from z~5 to z~0. We use a simple, non-parametric model which monotonically relates galaxy luminosities to the maximum circular velocity of dark matter halos (V_max) by preserving the observed galaxy luminosity function in order to match the halos in simulations with observed galaxies. The novel feature of the model is the use of the maximum circular velocity at the time of accretion, V_max,acc, for subhalos, the halos located within virial regions of larger halos. We argue that for subhalos in dissipationless simulations, V_max,acc reflects the luminosity and stellar mass of the associated galaxies better than the circular velocity at the epoch of observation, V_max,now. The simulations and our model L-V_max relation predict the shape, amplitude, and luminosity dependence of the two-point correlation function in excellent agreement with the observed galaxy clustering in the SDSS data at z~0 and in the DEEP2 samples at z~1 over the entire probed range of projected separations, 0.1<r_p/(Mpc/h)<10.0. In particular, the small-scale upturn of the correlation function from the power-law form in the SDSS and DEEP2 luminosity-selected samples is reproduced very well. At z~3-5, our predictions also match the observed shape and amplitude of the angular two-point correlation function of Lyman-break galaxies (LBGs) on both large and small scales, including the small-scale upturn.Comment: 16 pages 11 figures, ApJ in pres

Frailty Identification in Prehospital Care: A Scoping Review of the Literature

The proportion of older adults is increasing worldwide. Frailty assessment in prehospital care was suggested to improve triage decisions and paramedics’ judgment. This study aimed to assess the scope and nature of available evidence around frailty identification in prehospital care. A systematic search of the literature was performed using MEDLINE, SCOPUS, CINHAL, and Web of Science to identify relevant articles published from January 2022 downwards. A list of indexed terms and their associated alternatives were pre-determined. Of the 71 identified and reviewed articles after removing duplicates, six articles were included in the review. Due to the heterogeneity of the included articles, the findings were described narratively. The findings of this review showed that the available evidence is limited and heterogenic. Two themes emerged from the findings of the included articles: 1) Paramedics’ Perceptions about Frailty Assessment in Prehospital Care and 2) Frailty Scores for Application in Prehospital Care. Paramedics recognised frailty assessment in pre-hospital care to be feasible and important. They highlighted the need for a simple and clear frailty score that could be used and mentioned to other healthcare professionals when handing over patients. Six frailty scores were reported to be used in prehospital care. The evidence around each frailty score is very limited. Overall, frailty assessment in prehospital care was shown to be important and feasible. Different frailty scores have been assessed for use in prehospital care. Further research investigating frailty identification in prehospital care is needed

Under-triage of older trauma patients in prehospital care: a systematic review

Background: It is argued that many older trauma patients are under-triaged in prehospital care which may adversely affect their outcomes. This systematic review aimed to assess prehospital under-triage rates for older trauma patients, the accuracy of the triage criteria, and the impact of prehospital triage decisions on outcomes. Methods: A computerised literature search using MEDLINE, Scopus, and CINHAL databases was conducted for studies published between 1966 and 2021 using a list of predetermined index terms and their associated alternatives. Studies which met the inclusion criteria were included and critiqued using the Critical Appraisal Skills Programme tool. Due to the heterogeneity of the included studies, narrative synthesis was used in this systematic review. Results: Of the 280 identified studies, 23 met the inclusion criteria. Current trauma triage guidelines have poor sensitivity to identify major trauma and the need for TC care for older adults. Although modified triage tools for this population have improved sensitivity, they showed significantly decreased specificity or were not applied to all older people. The issue of low rates of TC transport for positively triaged older patients is not well understood. Furthermore, the benefits of TC treatment for older patients remain uncertain. Conclusions: This systematic review showed that under-triage is an ongoing issue for older trauma patients in prehospital care and its impact on their outcomes is still uncertain. Further high-quality prospective research is needed to assess the accuracy of prehospital triage criteria, the factors other than the triage criteria that affect transport decisions, and the impact of under-triage on outcomes

Higgsless GUT Breaking and Trinification

Boundary conditions on an extra-dimensional interval can be chosen to break bulk gauge symmetries and to reduce the rank of the gauge group. We consider this mechanism in models with gauge trinification. We determine the boundary conditions necessary to break the trinified gauge group directly down to that of the standard model. Working in an effective theory for the gauge symmetry-breaking parameters on a boundary, we examine the limit in which the GUT-breaking sector is Higgsless and show how one may obtain the low-energy particle content of the minimal supersymmetric standard model. We find that gauge unification is preserved in this scenario, and that the differential gauge coupling running is logarithmic above the scale of compactification. We compare the phenomenology of our model to that of four-dimensional trinified theories.Comment: 22 pages, LaTeX, 2 eps figures (v3: discussion of mass scales clarified