Publications by authors named "E Timothy Walch"

Calcium carbonate (CaCO) is abundant on Earth, is a major component of marine biominerals and thus of sedimentary and metamorphic rocks and it plays a major role in the global carbon cycle by storing atmospheric CO into solid biominerals. Six crystalline polymorphs of CaCO are known-3 anhydrous: calcite, aragonite, vaterite, and 3 hydrated: ikaite (CaCO·6HO), monohydrocalcite (CaCO·1HO, MHC), and calcium carbonate hemihydrate (CaCO·½HO, CCHH). CCHH was recently discovered and characterized, but exclusively as a synthetic material, not as a naturally occurring mineral.

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Rapid increases in cell volume reduce the size of the extracellular space (ECS) and are associated with elevated brain tissue excitability. We recently demonstrated that astrocytes, but not neurons, rapidly swell in elevated extracellular potassium ([K] ) up to 26 mM. However, effects of acute astrocyte volume fluctuations on neuronal excitability in [K] have been difficult to evaluate due to direct effects on neuronal membrane potential and generation of action potentials.

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Astrocyte volume fluctuation is a physiological phenomenon tied closely to the activation of neural circuits. Identification of underlying mechanisms has been challenging due in part to use of a wide range of experimental approaches that vary between research groups. Here, we first review the many methods that have been used to measure astrocyte volume changes directly or indirectly.

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Background: Cerebral palsy (CP) refers to a non-progressive permanent lesion of the developing brain, which can manifest with motor function disability and various comorbidities and complications. However, there is little data on the correlation between motor and mental function in CP, as cognitive assessments are rarely the main focus of studies on children with CP.

Methods: We studied a large cohort of 381 children and adolescents with CP.

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The mature skeletons of hard corals, termed stony or scleractinian corals, are made of aragonite (CaCO). During their formation, particles attaching to the skeleton's growing surface are calcium carbonate, transiently amorphous. Here we show that amorphous particles are observed frequently and reproducibly just outside the skeleton, where a calicoblastic cell layer envelops and deposits the forming skeleton.

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