Grain fracture and crushing are known to influence the macroscopic mechanical behavior of granular materials and be influenced by factors such as grain composition, morphology, and microstructure. In ...this paper, we investigate grain fracture and crushing by combining synchrotron x-ray computed tomography and three-dimensional x-ray diffraction to study two granular samples undergoing uniaxial compaction. Our measurements provide details of grain kinematics, contacts, average intra-granular stresses, inter-particle forces, and intra-grain crystal and fracture plane orientations. Our analyses elucidate the complex nature of fracture and crushing, showing that: (1) the average stress states of grains prior to fracture vary widely in their relation to global and local trends; (2) fractured grains experience inter-particle forces and stored energies that are statistically higher than intact grains prior to fracture; (3) fracture plane orientations are primarily controlled by average intra-granular stress and contact fabric rather than the orientation of the crystal lattice; (4) the creation of new surfaces during fracture accounts for a very small portion of the energy dissipated during compaction; (5) mixing brittle and ductile grain materials alters the grain-scale fracture response. The results highlight an application of combined x-ray measurements for non-destructive in situ analysis of granular solids and provide details about grain fracture that have important implications for theory and modeling.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•High order (up to 10th) difference schemes on unstructured disordered node sets.•Spatially varying resolution, stencil optimisation and filtering.•High order boundary conditions for complex ...geometries.•Simulations of isothermal Navier-Stokes equations.•Moderate to high Reynolds number flows through porous media.
Mesh-free methods have significant potential for simulations of flows in complex geometries, with the difficulties of domain discretisation greatly reduced. However, many mesh-free methods are limited to low order accuracy. In order to compete with conventional mesh-based methods, high order accuracy is essential. The Local Anisotropic Basis Function Method (LABFM) is a mesh-free method introduced in King et al. (2020) 20, which enables the construction of highly accurate difference operators on disordered node discretisations. Here, we introduce a number of developments to LABFM, in the areas of basis function construction, stencil optimisation, stabilisation, variable resolution, and high order boundary conditions. With these developments, direct numerical simulations of the Navier Stokes equations are possible at extremely high order (up to 10th order in characteristic node spacing internally). We numerically solve the isothermal compressible Navier Stokes equations for a range of geometries: periodic and channel flows, flows past a cylinder, and porous media. Excellent agreement is seen with analytical solutions, published numerical results (using a spectral element method), and experiments. The potential of the method for direct numerical simulations in complex geometries is demonstrated with simulations of subsonic and transonic flows through an inhomogeneous porous media at pore Reynolds numbers up to Rep=968.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
There is some limited evidence for the presence of viruses in herniated disc material including a previous case series that claimed to provide "unequivocal evidence of the presence of herpes virus ...DNA in intervertebral disc specimens of patients with lumbar disc herniation suggesting the potential role of herpes viruses as a contributing factor to the pathogenesis of degenerative disc disease". This study has not been replicated. The objective of our study was to determine if viruses were present in herniated disc fragments in participants with a prior history of back pain.
We recruited fifteen participants with a history of prior low-back pain prior to undergoing disc herniation surgery in the lumbar spine. Harvested disc samples were subject to next generation sequencing for detection of both RNA and DNA viral pathogens. Additionally, samples were analysed by a broadly reactive PCR targeting herpesviral DNA. Ethics approval was granted by the Human Research Ethics Committees of both Murdoch University, and St John of God Hospital, Western Australia.
Of the fifteen research participants, 8 were female. Mean age was 49.4 years (SD 14.5 yrs) with a range of 24-70 years. All participants had prior back pain with mean time since first ever attack being 8.8 years (SD 8.8 yrs). No samples contained significant DNA sequences relating to known human viral agents. Inconsequential retroviral sequences were commonly found and were a mixture of putative animal and human retroviral protein coding segments. All samples were negative for herpesvirus DNA when analysed by pan-herpesvirus PCR.
This study found no viral pathogens in any intervertebral disc fragments of patients who had previous back pain and underwent discectomy for disc herniation and thus it is unlikely that viruses are associated with disc herniation, however given the contradiction between key studies enhanced replication of this experiment is recommended.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Reducing exposure to obesogens is a strategy for preventing obesity.
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•There is an expanding global obesity pandemic.•Ubiquitous environmental chemicals called obesogens play a vital ...role in the obesity pandemic.•Exposure to obesogens occurs throughout the life course from before conception until death.•Development is the most sensitive time for obesogens to impact future weight gain across the lifespan and generations.•Obesogens can act via epigenetic mechanisms.•There is a need to expand understanding of the obesogen paradigm to clinicians and consumers.
Obesity is a multifactorial disease with both genetic and environmental components. The prevailing view is that obesity results from an imbalance between energy intake and expenditure caused by overeating and insufficient exercise. We describe another environmental element that can alter the balance between energy intake and energy expenditure: obesogens. Obesogens are a subset of environmental chemicals that act as endocrine disruptors affecting metabolic endpoints. The obesogen hypothesis posits that exposure to endocrine disruptors and other chemicals can alter the development and function of the adipose tissue, liver, pancreas, gastrointestinal tract, and brain, thus changing the set point for control of metabolism. Obesogens can determine how much food is needed to maintain homeostasis and thereby increase the susceptibility to obesity. The most sensitive time for obesogen action is in utero and early childhood, in part via epigenetic programming that can be transmitted to future generations. This review explores the evidence supporting the obesogen hypothesis and highlights knowledge gaps that have prevented widespread acceptance as a contributor to the obesity pandemic. Critically, the obesogen hypothesis changes the narrative from curing obesity to preventing obesity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Background:
The most important reason for treating children with Prader-Willi syndrome (PWS) with GH is to optimize their body composition.
Objectives:
The aim of this ongoing study was to determine ...whether long-term GH treatment can counteract the clinical course of increasing obesity in PWS by maintaining the improved body composition brought during early treatment.
Setting:
This was a multicenter prospective cohort study.
Methods:
We have been following 60 prepubertal children for 8 years of continuous GH treatment (1 mg/m2/d ≅ 0.035 mg/kg/d) and used the same dual-energy x-ray absorptiometry machine for annual measurements of lean body mass and percent fat.
Results:
After a significant increase during the first year of GH treatment (P < .0001), lean body mass remained stable for 7 years at a level above baseline (P < .0001). After a significant decrease in the first year, percent fat SD score (SDS) and body mass index SDS remained stable at a level not significantly higher than at baseline (P = .06, P = .14, resp.). However, body mass index SDSPWS was significantly lower after 8 years of GH treatment than at baseline (P < .0001). After 8 years of treatment, height SDS and head circumference SDS had completely normalized. IGF-1 SDS increased to +2.36 SDS during the first year of treatment (P < .0001) and remained stable since then. GH treatment did not adversely affect glucose homeostasis, serum lipids, blood pressure, and bone maturation.
Conclusion:
This 8-year study demonstrates that GH treatment is a potent force for counteracting the clinical course of obesity in children with PWS.
Highlights • The role of decompressive craniectomy for traumatic brain injury remains controversial. • It is undoubtedly a lifesaving intervention. • However, reduction in mortality is translated ...into survival with severe disability. • A broader ethical debate is now needed regarding ongoing use of the procedure.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
This clinical trial compared everolimus, an immunosuppressive and antiproliferative agent, with azathioprine in patients who had undergone cardiac transplantation. Everolimus reduced the incidence of ...both acute rejection and coronary vasculopathy, a serious disorder that causes deterioration of the graft.
A promising agent for management of rejection and vasculopathy.
Among recipients of heart transplants, vasculopathy of the allograft is the main cause of illness and death after the first year.
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Early immunologic and nonimmunologic endothelial damage may initiate pathologic remodeling, resulting in progressive luminal narrowing.
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The development of immunosuppressive agents to prevent acute allograft rejection and the proliferation of smooth-muscle cells may reduce the frequency and severity of vasculopathy.
Intravascular ultrasonography is a sensitive approach for the early detection of vasculopathy.
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If performed at the same sites at base line and one year after transplantation, ultrasonography can be used to evaluate the progression of intimal proliferation. . . .
•A novel high-order accurate incompressible SPH formulation is presented.•High-order consistency enforced ensuring uninhibited SPH spatial error convergence.•Hybrid technique combines high-order ...smoothing accuracy and second-order consistency.•Stabilising techniques proposed for collocated projection method based high-order SPH.•2-D/3-D tests validate accuracy and robustness of the proposed high-order SPH scheme.
Mesh-free methods such a smoothed particle hydrodynamics (SPH) have advantages over mesh-based methods for flow in complex domains but attaining consistent high-order accurate solutions with the conventional form of SPH has yet to be resolved. The high-order smoothing error dominates the SPH error until increasingly fine resolutions cause the low-order discretisation error to dominate; this is related to discretising a volume integral into a summation. In this paper, a high-order consistency correction based on modified SPH (MSPH) and the modified finite particle method (FPM) is proposed for improving the order of the limiting discretisation error. The new technique is an arbitrarily high-order extension of these schemes where the complexity of the consistency correction and the required computations are reduced by using simplified versions of the smoothing kernel derivatives. Tested in Eulerian form, the proposed high-order consistent SPH technique (HOCSPH) is combined with new high-order SPH kernel functions, designed to improve the order of the SPH smoothing error, and the resulting hybrid technique is shown to converge according to the smoothing error initially before converging according to the HOCPSH error once the latter becomes dominant. The initial high-order convergence lowers the computational effort required to achieve higher accuracy with hybrid HOCSPH in comparison to HOCSPH with second-order smoothing accuracy kernel functions. However, for highly irregular distributions it is found that the use of kernels with second-order smoothing accuracy provides more consistent convergence properties. A number of flows are simulated in 2-D and 3-D using the new HOCSPH technique in combination with the pressure projection method, and the results show that the method is accurate and able to model highly complex flow patterns. Some issues with stability of the projection method related to pressure–velocity collocation are identified, and several remedies are proposed. While effective for the test cases herein, these remedies are new in this context and require further attention for generalisation in future studies.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Intracranial pressure (ICP) includes the brain, optic nerve, and spinal cord pressures; it influences blood flow to those structures. Pathological elevation in ICP results in structural damage ...through various mechanisms, which adversely affects outcomes in traumatic brain injury and stroke. Currently, invasive procedures which tap directly into the cerebrospinal fluid are required to measure this pressure. Recent fluidic engineering modelling analogous to the ocular vascular flow suggests that retinal venous pulse amplitudes are predictably influenced by downstream pressures, suggesting that ICP could be estimated by analysing this pulse signal. We used this modelling theory and our photoplethysmographic (PPG) retinal venous pulse amplitude measurement system to measure amplitudes in 30 subjects undergoing invasive ICP measurements by lumbar puncture (LP) or external ventricular drain (EVD). We estimated ICP from these amplitudes using this modelling and found it to be accurate with a mean absolute error of 3.0 mmHg and a slope of 1.00 (r = 0.91). Ninety-four percent of differences between the PPG and invasive method were between - 5.5 and + 4.0 mmHg, which compares favourably to comparisons between LP and EVD. This type of modelling may be useful for understanding retinal vessel pulsatile fluid dynamics and may provide a method for non-invasive ICP measurement.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
On-orbit firings of both liquid and solid rocket motors provide localized disturbances to the plasma in the upper atmosphere. Large amounts of energy are deposited to ionosphere in the form of ...expanding exhaust vapors which change the composition and flow velocity. Charge exchange between the neutral exhaust molecules and the background ions (mainly O + ) yields energetic ion beams. The rapidly moving pickup ions excite plasma instabilities and yield optical emissions after dissociative recombination with ambient electrons. Line-of-sight techniques for remote measurements rocket burn effects include direct observation of plume optical emissions with ground and satellite cameras, and plume scatter with UHF and higher frequency radars. Long range detection with HF radars is possible if the burns occur in the dense part of the ionosphere. The exhaust vapors initiate plasma turbulence in the ionosphere that can scatter HF radar waves launched from ground transmitters. Solid rocket motors provide particulates that become charged in the ionosphere and may excite dusty plasma instabilities. Hypersonic exhaust flow impacting the ionospheric plasma launches a low-frequency, electromagnetic pulse that is detectable using satellites with electric field booms. If the exhaust cloud itself passes over a satellite, in situ detectors measure increased ion-acoustic wave turbulence, enhanced neutral and plasma densities, elevated ion temperatures, and magnetic field perturbations. All of these techniques can be used for long range observations of plumes in the ionosphere. To demonstrate such long range measurements, several experiments were conducted by the Naval Research Laboratory including the Charged Aerosol Release Experiment, the Shuttle Ionospheric Modification with Pulsed Localized Exhaust experiments, and the Shuttle Exhaust Ionospheric Turbulence Experiments.
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