Clumped isotope evidence for episodic, rapid flow of fluids in a mineralized fault system in the Peak District, UK

We have used clumped isotope thermometry to study a fault-hosted hydrothermal calcite vein associated with the Mississippi Valley Type (MVT) mineralization on the Derbyshire Platform in the southern Pennines, UK. This is the first published dataset obtained using a new mass spectrometer, MIRA, optimized for clumped isotope analysis and an associated clumped isotope-temperature calibration. We analysed multiple generations of vein growth at high spatial resolution in two transects across the vein. The vein grew episodically at temperatures between 40 and 100°C. We interpret each episode of growth as being associated with an increasing flux of formation waters from deep sedimentary basins next to the mineralized platform and an accompanying increase in the precipitation temperatures. Heat is conserved in the fluid as it ascends along the fault surface and, thus, flow must have been fast and restricted to short-lived pulses. The flux could have been driven by high pore pressures associated with rapid sedimentation, hydrocarbon generation and diagenesis in the basinal facies of the Visean Bowland-Hodder group. Natural hydraulic fracturing of shale units and failure of capillary seals, possibly triggered by uplift, allowed the release of fluids into aquifers within the sediment pile. The transmission of high pore fluid pressures from the shales to the fault zone, aided by the compressibility of the gas phase in two-phase pore fluids, may have resulted in fault rupture, accompanied by enhanced fracture permeability and rapid fluid flow. Vein growth ceased as pore pressures dissipated. Such behaviour is closely related to a seismic valve type model for mineralization

Adoptive gay father families: parent-child relationships and children's psychological adjustment

Findings are presented on a U.K. study of 41 gay father families, 40 lesbian mother families, and 49 heterosexual parent families with an adopted child aged 3–9 years. Standardized interview and observational and questionnaire measures of parental well-being, quality of parent–child relationships, child adjustment, and child sex-typed behavior were administered to parents, children, and teachers. The findings indicated more positive parental well-being and parenting in gay father families compared to heterosexual parent families. Child externalizing problems were greater among children in heterosexual families. Family process variables, particularly parenting stress, rather than family type were found to be predictive of child externalizing problems. The findings contribute to theoretical understanding of the role of parental gender and parental sexual orientation in child development

The Efficacy of Direct Current Stimulation for Lumbar Intertransverse Process Fusions in an Animal Model

Study Design. Posterolateral lumbar intertransverse process fusion using a rabbit model with autologous bone graft and direct current stimulation was compared with fusion achieved by using autologous bone graft alone.Objectives. To determine the efficacy of direct current electrical stimulation for the posterolateral lumbar intertransverse process fusion technique by using a 20-[mu]A current and the more recently developed 60-[mu]A current delivered by an implantable direct current stimulator.Summary of Background Data. Previous studies have demonstrated a positive effect of direct current electrical stimulation on posterior spinal fusion techniques. However, until recently, the environment of an intertransverse fusion was not well simulated. The current research examined the posterolateral lumbar intertransverse process fusion technique with direct current electrical stimulation using a rabbit model. This appears to parallel human fusion techniques more closely and allows for lower cost and technical ease.Methods. In this study, 44 adult New Zealand white rabbits underwent an L5-L6 intertransverse process fusion. All the fusions used an autologous bone graft obtained from bilateral posterior iliac crests. A device was implanted in all the rabbits subcutaneously, and they were divided randomly into three groups: a sham or nonfunctioning group, a 20-[mu]A low-current stimulator group, and a 60-[mu]A higher-current stimulator group. Spinal fusion was evaluated radiographically, histologically, and manually as well as by biomechanical testing 5 weeks after surgery.Results. Radiographic grades, manual palpation, biomechanical strength, and stiffness showed an increasing trend from sham or inactive stimulator groups to low-current and then to high-current stimulator groups. Histologic analysis revealed that the higher-current stimulator showed that, statistically, the healing response of the host tissue to the autograft had increased significantly, as compared with the sham.Conclusions. Direct current electrical stimulation is efficacious in improving both the healing rate and strength in this posterolateral lumbar fusion model. In addition, it appears that this effect is enhanced by increasing the stimulation current from 20 [mu]A to 60 [mu]A