Environmental Public Health Awaits Rediscovery

Preventing environmental exposures that threaten human health remains among the best but least attended to opportunities to improve everyone’s health. For more than a decade, medical care concerns, exacerbated by voracious competition among medical empires and the implacably growing number of uninsured, have often been misconstrued as constituting a complete agenda for health system reform. The authors explain the predicament from an historical perspective — how defining events moved U.S. health policy away from protecting the public against dangerous exposures toward unrealistic expectations that doctors will fix whatever goes wrong, at least for individuals with ample medical insurance. They explain how environmentally oriented public health is uniquely suited to help organized medical care with its biggest headache: how to restrain expenditures while producing health. The authors provide specific examples of what has been lost and a prescription for how the U.S. could become the first among nations to strategically link public health and increasingly organized medical care to improve population health

Peeling Away the Taken-For-Grantedness of Research Subjectivities: Orienting to the Phenomenological

Qualitative research is a multidisciplinary field of practice that acknowledges and values the situatedness and subjectivities of the researcher. Therefore, reflexively accounting for one’s subjectivities is a crucial part of a research report. Less discussed is how subjective understandings are historically, culturally, and socially mediated, often challenging researchers’ abilities to orient themselves critically to this self-reflective undertaking. Phenomenology is a philosophical approach investigating how phenomena such as subjectivity are constituted in experience. This makes phenomenology an essential resource for understanding how complex subjective responses manifest differently depending on one’s orientation to the situation. This paper aims to familiarize qualitative research instructors and learners with a series of phenomenological activities that have proven helpful in disclosing multiple ways subjectivities are historically and contextually mediated, embodied, and technologically modified

Hearing through your eyes: neural basis of audiovisual cross-activation, revealed by transcranial alternating current stimulation

Some people experience auditory sensations when seeing visual flashes or movements. This prevalent synaesthesia-like ‘visual-evoked auditory response’ (vEAR) could result either from over-exuberant cross-activation between brain areas, and/or reduced inhibition of normally-occurring cross-activation. We have used transcranial alternating current stimulation (tACS) to test these theories. We applied tACS at 10Hz (alpha-band frequency) or 40Hz (gamma-band), bilaterally either to temporal or occipital sites, while measuring same/different discrimination of paired auditory (A) versus visual (V) 'Morse code' sequences. At debriefing, participants were classified as vEAR or non-vEAR depending on whether they reported 'hearing' the silent flashes. In non-vEAR participants, temporal 10Hz tACS caused impairment of A performance, which correlated with improved V; conversely under occipital tACS, poorer V performance correlated with improved A. This reciprocal pattern suggests that sensory cortices are normally mutually inhibitory, and that alpha-frequency tACS may bias the balance of competition between them. vEAR participants showed no tACS effects, consistent with reduced inhibition, or enhanced cooperation between modalities. In addition, temporal 40Hz tACS impaired V performance, specifically in individuals who showed a performance advantage for V (relative to A). Gamma-frequency tACS may therefore modulate the ability of these individuals to benefit from recoding flashes into the auditory modality, possibly by disrupting cross-activation of auditory areas by visual stimulation. Our results support both theories, suggesting that vEAR may depend on disinhibition of normally-occurring sensory cross-activation, which may be expressed more strongly in some individuals. Furthermore, endogenous alpha and gamma-frequency oscillations may function respectively to inhibit or promote this cross-activation

Airborne Tomographic Swath Ice Sounding Processing System

Glaciers and ice sheets modulate global sea level by storing water deposited as snow on the surface, and discharging water back into the ocean through melting. Their physical state can be characterized in terms of their mass balance and dynamics. To estimate the current ice mass balance, and to predict future changes in the motion of the Greenland and Antarctic ice sheets, it is necessary to know the ice sheet thickness and the physical conditions of the ice sheet surface and bed. This information is required at fine resolution and over extensive portions of the ice sheets. A tomographic algorithm has been developed to take raw data collected by a multiple-channel synthetic aperture sounding radar system over a polar ice sheet and convert those data into two-dimensional (2D) ice thickness measurements. Prior to this work, conventional processing techniques only provided one-dimensional ice thickness measurements along profiles

A 3D coupled finite element model for simulating mechanical regain in self-healing cementitious materials

This study presents a new 3D coupled model for simulating self-healing cementitious materials. The mechanical behaviour is described using a damage-healing cohesive zone model that is implemented using a new embedded strong discontinuity hexahedral element. The transport component of the model considers the flow of healing agent through discrete cracks, governed by the mass balance equation with Darcy’s law being employed for the healing agent flux. The dependency of the mechanical response on the healing agent transport is accounted for through a local crack filling function that represents the amount of healing agent available to undergo healing. The healing itself is described by a generalised healing front model that simulates the accumulation of healed material within the crack, emanating from the crack faces. The performance of the model is demonstrated through the consideration of a healing front study and experimental tests on self-healing cementitious specimens. The examples consider a vascular self-healing cementitious specimen that uses a sodium silicate solution as the healing agent and the autogenous healing of a cementitious specimen with and without crystalline admixtures. The results of the validations show that the model is able to reproduce the experimentally observed behaviour with good accuracy

The application of a curing front model to simulate healing in a cementitious microbial system

This study investigates the ability of a coupled finite element model to simulate Microbially Induced Calcium Carbonate Precipitation (MICP) and associated healing behaviour in cementitious samples. This recent coupled 3D model was first developed for simulating the behaviour of autonomic healing systems in cementitious structural elements. It employs a cohesive zone constitutive model for simulating the damage-healing behaviour of an embedded interface within 3D continuum elements. Fluid flow is simulated using a mass balance equation and Darcy’s law. Healing is computed via a generalised curing front model that simulates the accumulation of healed material within a crack. The research reported in this article demonstrates that the curing front model can be calibrated to predict healing from MICP in cementitious specimens with good accuracy