Cervical Spine Tolerance And Response In Compressive Loading Modes Including Combined Compression And Lateral Bending

Injuries in motor vehicle accidents continue to be a serious and costly societal problem. Automotive safety researchers have observed noticeable lateral bending of the anthropomorphic test device (ATD) neck prior to or in conjunction with head impact with the vehicle roof in rollover crash tests. Since there is scant data available about the effects of lateral bending on overall compressive tolerance of the human cervical spine, it is unknown if the presence of lateral bending is important to consider during impacts with the apex of the head. Compressive injury tolerance has historically been reported by identifying the axial force at the time of injury measured at the base of the neck, however, axial force at failure exhibits variation and this has been attributed to the alignment of the cervical vertebra and the end conditions of test methodology used. Robust and sensitive injury metrics for human compressive cervical spine tolerance that can be applied to a wide range of loading conditions and head-neck postures would be useful in evaluating and developing mechanically meaningful and robust anthropomorphic test devices (ATDs) and their associated injury assessment reference values (IARVs). As the Hybrid III ATD continues to be used in automotive rollover applications, interpretation of measured neck loads in this testing mode would be aided by a better understanding of human cervical spine response and tolerance in compression dominated combined loading scenarios and their correlation to Hybrid III ATD neck responses. The effects of lateral bending on the compressive cervical spine dynamic response and tolerance was investigated through post mortem human subject (PMHS) head-neck complex experimentation. Similar to findings of previous researchers, the initial cervical posture influenced the mechanical response of the spine and the loads at failure. The results were combined with available historical compressive cervical spine tolerance studies that include head and neck dynamics, cervical kinetics and known end conditions. A re-evaluation of the axial force tolerance of the PMHS cervical spine as well as derivation of a mechanistically relevant eccentricity based injury tolerance metric that can be applied to a wider range of loading vectors and initial cervical spine postures were conducted. Finally, the Hybrid III ATD neck compressive injury assessment reference values (IARVs) were evaluated through reconstruction of PMHS experiments with known injury outcomes using the Hybrid III head and neck assembly. Results are consistent with the currently defined IARVs and provide additional experimental support of the IARVs in loading modes that are known to result in PMHS compressive cervical injuries

Mission Creep and Wiretap Act \u27Super Warrants\u27: A Cautionary Tale

Congress enacted the Wiretap Act in 1968 in an effort to combat organized crime while safeguarding the privacy of innocent Americans. However, the Act instead served to legitimize wiretapping, and its privacy protections have eroded over time. As a result, there has been a significant increase in wiretapping in the decades since the Act’s passage. As technology evolves, the Wiretap Act does less to protect Americans’ private communications from government interception. Nevertheless, policy makers see the Wiretap Act, with its “super-warrant” procedures, as the gold standard for statutory privacy protection. To the contrary, when considering how to regulate new and powerful surveillance technologies, advocates must not reflexively rely on the language of the Wiretap Act as a model for adequate privacy safeguards. They must consider whether, given the Act’s apparent flaws, it is possible to meaningfully balance the invasiveness of a new technique with the preservation of individual privacy. If so, drafters should focus on crafting statutory language that better implements the intended safeguards of the Act than the Act itself has. This Article describes the deterioration of the Wiretap Act’s protections and should serve as a cautionary tale to advocates as they propose new legislation in the face of modern surveillance tools

Towards a More Robust Lower Neck Compressive Injury Tolerance - An Approach Combining Multiple Test Methodologies

Objective.The compressive tolerance of the cervical spine has traditionally been reported in terms of axial force at failure. Previous studies suggest that axial compressive force at failure is particularly sensitive to the alignment of the cervical vertebra and the end conditions of the test methodology used. The present study was designed to develop a methodology to combine the data of previous experiments into a diverse dataset utilizing multiple test methods to allow for the evaluation of the robustness of current and proposed eccentricity based injury criteria. Methods. Data was combined from two studies composed of dynamic experiments including whole cervical spine and head kinematics that utilized different test methodologies with known end conditions, spinal posture, injury outcomes and measured kinetics at the base of the neck. Loads were transformed to the center of the C7-T1 intervertebral disc and the eccentricity of the sagittal plane resultant force relative to the center of the disc was calculated. The correlation between sagittal plane resultant force and eccentricity at failure was evaluated and compared to the correlation between axial force and sagittal plane moment and axial force alone. Results. Accounting for the eccentricity of the failure loads decreased the scatter in the failure data when compared to the linear combination of axial force and sagittal plane moment and axial force alone. A correlation between axial load and sagittal plane flexion moment at failure (R2 = 0.44) was identified. The sagittal plane extension moment at failure did not have an identified correlation with the compressive failure load for the tests evaluated in this data set (R2 = 0.001). The coefficients of determination for the linear combinations of sagittal plane resultant force with anterior and posterior eccentricity are 0.56 and 0.29 respectively. These correlations are an improvement compared to the combination of axial force and sagittal plane moment. Conclusions. Results using the outlined approach indicate that the combination of lower neck sagittal plane resultant force and the anterior-posterior eccentricity at which the load is applied generally correlate with the type of cervical damage identified. These results show promise at better defining the tolerance for compressive cervical fractures in male Post Mortem Human Subjects (PMHS) than axial force alone. The current analysis requires expansion to include more tolerance data so the robustness of the approach across various applied loading vectors and cervical postures can be evaluated

Underdiagnosis of mild cognitive impairment: A consequence of ignoring practice effects

INTRODUCTION: Longitudinal testing is necessary to accurately measure cognitive change. However, repeated testing is susceptible to practice effects, which may obscure true cognitive decline and delay detection of mild cognitive impairment (MCI). METHODS: We retested 995 late-middle-aged men in a ∼6-year follow-up of the Vietnam Era Twin Study of Aging. In addition, 170 age-matched replacements were tested for the first time at study wave 2. Group differences were used to calculate practice effects after controlling for attrition effects. MCI diagnoses were generated from practice-adjusted scores. RESULTS: There were significant practice effects on most cognitive domains. Conversion to MCI doubled after correcting for practice effects, from 4.5% to 9%. Importantly, practice effects were present although there were declines in uncorrected scores. DISCUSSION: Accounting for practice effects is critical to early detection of MCI. Declines, when lower than expected, can still indicate practice effects. Replacement participants are needed for accurately assessing disease progression.Published versio

Modelado morfodinámico de una playa encajada: rol de las fuentes para el forzado

Modelling the response of sandy beaches to sea level rise is a major scientific challenge and several types of models can be applied. Given the long-time scales involved, different sources for model forcing must be combined (wave and sea-level, e.g., from buoys or hindcast models). We here apply the XBeach process-based morphodynamic model and the Q2Dmorfo reducedcomplexity model to El Castell, a Mediterranean embayed beach. The models are first calibrated with data measured during 161 days with an AWAC at 14 m depth in front of the beach. XBeach predicts reasonably well the bathymetric dynamics while Q2Dmorfo can only reproduce the shoreline evolution. The calibrated versions of the models are then applied using other potential forcing sources. The source for sea level does not affect the results but both models are sensitive to the wave forcing source.Peer ReviewedPostprint (published version

Influence of young adult cognitive ability and additional education on later-life cognition

How and when education improves cognitive capacity is an issue of profound societal importance. Education and later-life education-related factors, such as occupational complexity and engagement in cognitive-intellectual activities, are frequently considered indices of cognitive reserve, but whether their effects are truly causal remains unclear. In this study, after accounting for general cognitive ability (GCA) at an average age of 20 y, additional education, occupational complexity, or engagement in cognitive-intellectual activities accounted for little variance in late midlife cognitive functioning in men age 56-66 (n = 1009). Age 20 GCA accounted for 40% of variance in the same measure in late midlife and approximately 10% of variance in each of seven cognitive domains. The other factors each accounted for <1% of the variance in cognitive outcomes. The impact of these other factors likely reflects reverse causation-namely, downstream effects of early adult GCA. Supporting that idea, age 20 GCA, but not education, was associated with late midlife cortical surface area (n = 367). In our view, the most parsimonious explanation of our results, a meta-analysis of the impact of education, and epidemiologic studies of the Flynn effect is that intellectual capacity gains due to education plateau in late adolescence/early adulthood. Longitudinal studies with multiple cognitive assessments before completion of education would be needed to confirm this speculation. If cognitive gains reach an asymptote by early adulthood, then strengthening cognitive reserve and reducing later-life cognitive decline and dementia risk may really begin with improving educational quality and access in childhood and adolescence.Peer reviewe

Precision orbital dynamics from interstellar scintillation arcs for PSR J0437-4715

Intensity scintillations of radio pulsars are known to originate from interference between waves scattered by the electron density irregularities of interstellar plasma, often leading to parabolic arcs in the two-dimensional power spectrum of the recorded dynamic spectrum. The degree of arc curvature depends on the distance to the scattering plasma and its transverse velocity with respect to the line-of-sight. We report the observation of annual and orbital variations in the curvature of scintillation arcs over a period of 16 years for the bright millisecond pulsar, PSR J0437-4715. These variations are the signature of the relative transverse motions of the Earth, pulsar, and scattering medium, which we model to obtain precise measurements of parameters of the pulsar's binary orbit and the scattering medium itself. We observe two clear scintillation arcs in most of our $>$5000 observations and we show that they originate from scattering by thin screens located at distances $D_1 = 89.8 \pm 0.4$ pc and $D_2 = 124 \pm 3$ pc from Earth. The best-fit scattering model we derive for the brightest arc yields the pulsar's orbital inclination angle $i = 137.1 \pm 0.3^\circ$, and longitude of ascending node, $\Omega=206.3\pm0.4^\circ$. Using scintillation arcs for precise astrometry and orbital dynamics can be superior to modelling variations in the diffractive scintillation timescale, because the arc curvature is independent of variations in the level of turbulence of interstellar plasma. This technique can be used in combination with pulsar timing to determine the full three-dimensional orbital geometries of binary pulsars, and provides parameters essential for testing theories of gravity and constraining neutron star masses.Comment: 19 pages, 10 figures. Accepted for publication in Ap

Characteristics of meiofauna in extreme marine ecosystems: a review

Extreme marine environments cover more than 50% of the Earth’s surface and offer many opportunities for investigating the biological responses and adaptations of organisms to stressful life conditions. Extreme marine environments are sometimes associated with ephemeral and unstable ecosystems, but can host abundant, often endemic and well-adapted meiofaunal species. In this review, we present an integrated view of the biodiversity, ecology and physiological responses of marine meiofauna inhabiting several extreme marine environments (mangroves, submarine caves, Polar ecosystems, hypersaline areas, hypoxic/anoxic environments, hydrothermal vents, cold seeps, carcasses/sunken woods, deep-sea canyons, deep hypersaline anoxic basins [DHABs] and hadal zones). Foraminiferans, nematodes and copepods are abundant in almost all of these habitats and are dominant in deep-sea ecosystems. The presence and dominance of some other taxa that are normally less common may be typical of certain extreme conditions. Kinorhynchs are particularly well adapted to cold seeps and other environments that experience drastic changes in salinity, rotifers are well represented in polar ecosystems and loriciferans seem to be the only metazoan able to survive multiple stressors in DHABs. As well as natural processes, human activities may generate stressful conditions, including deoxygenation, acidification and rises in temperature. The behaviour and physiology of different meiofaunal taxa, such as some foraminiferans, nematode and copepod species, can provide vital information on how organisms may respond to these challenges and can provide a warning signal of anthropogenic impacts. From an evolutionary perspective, the discovery of new meiofauna taxa from extreme environments very often sheds light on phylogenetic relationships, while understanding how meiofaunal organisms are able to survive or even flourish in these conditions can explain evolutionary pathways. Finally, there are multiple potential economic benefits to be gained from ecological, biological, physiological and evolutionary studies of meiofauna in extreme environments. Despite all the advantages offered by meiofauna studies from extreme environments, there is still an urgent need to foster meiofauna research in terms of composition, ecology, biology and physiology focusing on extreme environments

Cryogenic Memory Architecture Integrating Spin Hall Effect based Magnetic Memory and Superconductive Cryotron Devices

One of the most challenging obstacles to realizing exascale computing is minimizing the energy consumption of L2 cache, main memory, and interconnects to that memory. For promising cryogenic computing schemes utilizing Josephson junction superconducting logic, this obstacle is exacerbated by the cryogenic system requirements that expose the technology's lack of high-density, high-speed and power-efficient memory. Here we demonstrate an array of cryogenic memory cells consisting of a non-volatile three-terminal magnetic tunnel junction element driven by the spin Hall effect, combined with a superconducting heater-cryotron bit-select element. The write energy of these memory elements is roughly 8 pJ with a bit-select element, designed to achieve a minimum overhead power consumption of about 30%. Individual magnetic memory cells measured at 4 K show reliable switching with write error rates below $10^{-6}$, and a 4x4 array can be fully addressed with bit select error rates of $10^{-6}$. This demonstration is a first step towards a full cryogenic memory architecture targeting energy and performance specifications appropriate for applications in superconducting high performance and quantum computing control systems, which require significant memory resources operating at 4 K.Comment: 10 pages, 6 figures, submitte