High pressure cosmochemistry applied to major planetary interiors: Experimental studies

The overall goal of this project is to determine properties of the H-He-C-N-O system, as represented by small molecules composed of these elements, that are needed to constrain theoretical models of the interiors of the major planets. Much of our work now concerns the H2O-NH3 system. This project is the first major effort to measure phase equilibria in binary fluid-solid systems in diamond anvil cells. Vibrational spectroscopy, direct visual observations, and X-ray crystallography of materials confined in externally heated cells are our primary experimental probes. We also are collaborating with the shockwave physics group at Lawrence Livermore Laboratory in studies of the equation of state of a synthetic Uranus fluid and molecular composition of this and other H-C-N-O materials under planetary conditions

Designed-in security for cyber-physical systems

An expert from academia, one from a cyber-physical system (CPS) provider, and one from an end asset owner and user offer their different perspectives on the meaning and challenges of 'designed-in security.' The academic highlights foundational issues and talks about emerging technology that can help us design and implement secure software in CPSs. The vendor's view includes components of the academic view but emphasizes the secure system development process and the standards that the system must satisfy. The user issues a call to action and offers ideas that will ensure progress

Properties of planetary fluids at high pressure and temperature

In order to derive models of the interiors of Uranus, Neptune, Jupiter and Saturn, researchers studied equations of state and electrical conductivities of molecules at high dynamic pressures and temperatures. Results are given for shock temperature measurements of N2 and CH4. Temperature data allowed demonstration of shock induced cooling in the the transition region and the existence of crossing isotherms in P-V space

Temporary vascular shunting in vascular trauma: A 10-year review from a civilian trauma centre

BACKGROUND: Temporary intravascular shunts (TIVSs) can replace immediate definitive repair as a damage control procedure in vascular trauma. We evaluated their use in an urban trauma centre with a high incidence of penetrating trauma. METHOD: A retrospective chart review of all patients treated with a TIVS in a single centre between January 2000 and December 2009. RESULTS: Thirty-five TIVSs were placed during the study period: 22 were part of a damage control procedure, 7 were inserted at a peripheral hospital without vascular surgical expertise prior to transfer, and 6 were used during fixation of a lower limb fracture with an associated vascular injury. There were 7 amputations and 5 deaths, 4 of the TIVSs thrombosed, and a further 3 dislodged or migrated. Twenty-five patients underwent definitive repair with an interposition graft, 1 primary anastomosis was achieved, and 1 extra-anatomical bypass was performed. Five patients with non-viable limbs had the vessel ligated. CONCLUSIONS: A TIVS in the damage control setting is both life- and limb-saving. These shunts can be inserted safely in a facility without access to a surgeon with vascular surgery experience if there is uncontrollable bleeding or the delay to definitive vascular surgery is likely to be more than 6 hours. A definitive procedure should be performed within 24 hours

N-type calcium current, Cav2.2, is enhanced in small diameter sensory neurons isolated from Nf1+/− mice

Major aspects of neuronal function are regulated by Ca2+ including neurotransmitter release, excitability, developmental plasticity, and gene expression. We reported previously that sensory neurons isolated from a mouse model with a heterozygous mutation of the Nf1 gene (Nf1+/−) exhibited both greater excitability and evoked release of neuropeptides compared to wildtype mice. Furthermore, augmented voltage-dependent sodium currents but not potassium currents contribute to the enhanced excitability. To determine the mechanisms giving rise to the enhanced release of substance P and calcitonin gene-related peptide in the Nf1+/− sensory neurons, the potential differences in the total voltage-dependent calcium current (ICa) as well as the contributions of individual Ca2+ channel subtypes were assessed. Whole-cell patch-clamp recordings from small diameter capsaicin-sensitive sensory neurons demonstrated that the average peak ICa densities were not different between the two genotypes. However, by using selective blockers of channel subtypes, the current density of N-type (Cav2.2) ICa was significantly larger in Nf1+/− neurons compared to wildtype neurons. In contrast, there were no significant differences in L-, P/Q- and R-type currents between the two genotypes. Quantitative real-time PCR measurements made from the isolated but intact dorsal root ganglia indicated that N-type (Cav2.2) and P/Q-type (Cav2.1) Ca2+ channels exhibited the highest mRNA expression levels although there were no significant differences in the levels of mRNA expression between the genotypes. These results suggest that the augmented N-type (Cav2.2) ICa observed in the Nf1+/− sensory neurons does not result from genomic differences but may reflect post-translational or some other non-genomic modifications. Thus, our results demonstrate that sensory neurons from Nf1+/− mice, exhibit increased N-type ICa and likely account for the increased release of substance P and calcitonin gene-related peptide that occurs in Nf1+/− sensory neurons

Rapid ice aggregation process revealed through triple-wavelength Doppler spectra radar analysis

Rapid aggregation of ice particles has been identified by combining data from three co-located, vertically-pointing radars operating at different frequencies. A new technique has been developed that uses the Doppler spectra from these radars to retrieve the vertical profile of ice particle size distributions. The ice particles grow rapidly from a maximum size of 0.75 mm to 5 mm while falling less than 500 m and in under 10 minutes. This rapid growth is shown to agree well with theoretical estimates of aggregation, with aggregation efficiency close to 1, and is inconsistent with other growth processes, e.g. growth by deposition, riming. The aggregation occurs in the middle of the cloud, and is not present throughout the entire lifetime of the cloud. However, the layer of rapid aggregation is very well defined, at a constant height, where the temperature is −15 °C, and lasts for at least 20 minutes (approximate horizontal distance: 24 km). Immediately above this layer, the radar Doppler spectra is bi-modal, which signals the formation of new small ice particles at that height. We suggest that these newly formed particles, at approximately −15 °C, grow dendritic arms, enabling them to easily interlock and accelerate the aggregation process. The estimated aggregation efficiency in the studied cloud is between 0.7 and 1, consistent with recent laboratory studies for dendrites at this temperature. A newly developed method for retrieving the ice particle size distribution using the Doppler spectra allows these retrievals in a much larger fraction of the cloud than existing DWR methods. Through quantitative comparison of the Doppler spectra from the three radars we are able to estimate the ice particle size distribution at different heights in the cloud. Comparison of these size distributions with those calculated with more basic radar-derived values and more restrictive assumptions agree very well; however, the newly developed method allows size distribution retrieval in a larger fraction of the cloud because it allows us to isolate the signal from the larger (non-Rayleigh scattering) particles in the distribution and allows for deviation from the assumed shape of the distribution

The effect of lockdown on intentional and nonintentional injury during the COVID-19 pandemic in Cape Town, South Africa: A preliminary report

Background. In response to the coronavirus pandemic, lockdown restrictions and a ban on alcohol sales were introduced in South Africa. Objectives. To investigate the impact of lockdown measures on the number of patients who visited a tertiary urban trauma centre. Methods. The period of investigation was from 1 February to 30 June 2020 and was segmented into three intervals: pre-lockdown (February and March 2020), hard lockdown (April and May 2020) and immediately post lockdown (June 2020). The electronic HECTIS health record registry was interrogated for the total number of patients that were seen per month. These were further categorised according to mechanism of injury (stab, gunshot, blunt assault and road traffic injuries). Penetrating (stab and gunshot) and blunt assault victims were collectively grouped as violent trauma. Results. The mean total number of patients seen decreased by 53% during the hard lockdown period. There was a moderate reduction (15%) in patients with gunshot injuries seen during the hard lockdown phase, but there was an 80% increase in the post-lockdown period. The proportion of patients injured in road traffic collisions pre lockdown, hard lockdown and immediate post lockdown was 16.4%, 8.9% and 11.1%, respectively. Patients injured in road traffic collisions decreased by 74% during the hard lockdown period and maintained a reduction of 32% during the immediate post-lockdown period. The mean total number of patients who visited the trauma unit returned to pre-lockdown levels in June. Conclusions. There was an overall trend of reduced number of patients who visited the trauma unit during the hard lockdown period; however, these numbers returned to pre-lockdown levels during the immediate post-lockdown period. The number of road traffic injury admissions remained reduced during all three phases of lockdown, while the number of gunshot victims increased substantially during the post-lockdown period

He II Heat Exchanger Test Unit for the LHC Inner Triplet

The Inner Triplet Heat Exchanger Test Unit (IT-HXTU) is a 30-m long thermal model designed at Fermilab, built in US industry, fully automated and tested at CERN as part of the US LHC program to develop the LHC Interaction Region quadrupole system. The cooling scheme of the IT-HXTU is based on heat exchange between stagnant pressurized He II in the magnet cold mass and saturated He II (two-phase) flowing in a heat exchanger located outside of and parallel to the cold mass. The purposes of this test are, among others, to validate the proposed cooling scheme and to define an optimal control strategy to be implemented in the future LHC accelerator. This paper discusses the results for the heat exchanger test runs and emphasizes the thermal and hydraulic behavior of He II for the inner triplet cooling scheme

Effects of regional and local stresses on fault slip tendency in the southern Taranaki Basin, New Zealand

© 2019 Elsevier Ltd Determining the potential for faults to slip is widely employed for evaluating fault slip potential and associated earthquake hazards, and characterising hydrocarbon seal integrity and reservoir properties. Here we use borehole and 3D seismic reflection data to estimate stress orientations and magnitudes, fault geometries and slip tendency in the southern Taranaki Basin, New Zealand. Late Cenozoic normal faults in the basin range in strike from E-W to NE-SW and are associated with stress changes from basin to borehole scales. The Maui and Maari-Manaia regions, part of the eastern mobile belt, show a strike-slip/normal stress regime (SHmax ≥ Sv > Shmin). The Tui region, part of the western stable platform, shows a normal stress regime (Sv > SHmax > Shmin). Both regions have a mean SHmax azimuth of ENE-WSW. Although the southern Taranaki basin is undergoing active deformation at plate tectonic scales, the stress magnitudes appear insufficiently high to reactivate the faults assuming a classic coefficient of friction. SHmax azimuths and SHmax:Sv magnitude ratios vary locally between boreholes and with depth. A borehole that intersects an inactive seismic-scale fault and borehole-scale faults over a 150-m interval shows SHmax to rotate by up to 30° proximal to the faults, which are favourably orientated for slip in both strike-slip and normal regimes. The small borehole-scale faults may, however, be active within the inactive seismic scale fault's damage zone. We highlight changes of slip tendency along faults resulting from local variations in the stress field and non-planar fault geometries that could not be resolved using only seismic reflection data and regional stress tensor. In the Taranaki Basin additional sub-seismic fault mapping, stress information and mechanical rock property testing are required to realise the potential of stress-based prediction of along-fault permeability and fluid migration