Succeeding from Nature: The Non-Human Agency of Portuguese Cork

Non-human life has economic agency. It acts on the cultural values of products. Naturalness is an important property in the market and imbues vibrant materials with organic, healthy, traditional and other contingent properties. However, “natural” products can be succeeded in form and function by “synthetic” alternatives. Their value is further affected by non-humans. Our signal case explores Portuguese cork-bark, an agroforestry product grown in the montado, a biodiverse managed mosaic landscape of forestry and farming. The natural value of cork bottle stoppers is based on their effect on wine flavour. Oxygen permeable cork enables beneficial ageing to enhance flavour, whereas cork contaminated with taint degrades wine. Synthetic stoppers recreate the form and function of corks without being a vector for contamination. A succession from natural cork stoppers to reliable artificial polyethylene corks led to a decline in demand for cork bark and negative impacts on montado biodiversity. Yet here we demonstrate that such successions can be reversed as the affective properties of cork bark products became revalued with improvements in manufacturing, increasing concern for environmental sustainability and rising consumer demand for natural products. This leads us to explore further the dynamics between natural goods and synthetic replacements. We argue that rather than being two discrete domains of reality, natural and artificial products are both co-produced through assemblages of human and non-human action. Understanding succession between “natural” and “artificial” products enables new insights in to the geographies of non-human agency

New Ce Heavy-Fermion System: CeCu

We have discovered a new heavy-fermion system, CeCu6, with a large susceptibility (=0.027 emu/mole G at 1.5 K) and a large, temperature-dependent specific heat below 10 K that is 840 mJ/mole K2 at 1.8 K and extrapolates to 1.6 J/mole K2 at T=0 in analogy with CeAl3. High-field specific-heat measurements agree almost perfectly with a narrow-band picture first proposed for UBe13. © 1984 The American Physical Society

The α1-adrenergic receptors: diversity of signaling networks and regulation

The α1-adrenergic receptor (AR) subtypes (α1a, α1b, and α1d) mediate several physiological effects of epinephrineand norepinephrine. Despite several studies in recombinant systems and insightfrom genetically modified mice, our understanding of the physiological relevance and specificity of the α1-AR subtypes is still limited. Constitutive activity and receptor oligomerization have emerged as potential features regulating receptor function. Another recent paradigm is that βarrestins and G protein-coupled receptors themselves can act as scaffolds binding a variety of proteins and this can result in growing complexity of the receptor-mediated cellular effects. The aim of this review is to summarize our current knowledge on some recently identified functional paradigms and signaling networks that might help to elucidate the functional diversity of the α1-AR subtypes in various organs

Threshold velocity for environmentally-assisted cracking in low alloy steels

Environmentally Assisted Cracking (EAC) in low alloy steels is generally believed to be activated by dissolution of MnS inclusions at the crack tip in high temperature LWR environments. EAC is the increase of fatigue crack growth rate of up to 40 to 100 times the rate in air that occurs in high temperature LWR environments. A steady state theory developed by Combrade, suggested that EAC will initiate only above a critical crack velocity and cease below this same velocity. A range of about twenty in critical crack tip velocities was invoked by Combrade, et al., to describe data available at that time. This range was attributed to exposure of additional sulfides above and below the crack plane. However, direct measurements of exposed sulfide densities on cracked specimens were performed herein and the results rule out significant additional sulfide exposure as a plausible explanation. Alternatively, it is proposed herein that localized EAC starting at large sulfide clusters reduces the calculated threshold velocity from the value predicted for a uniform distribution of sulfides. Calculations are compared with experimental results where the threshold velocity has been measured, and the predicted wide range of threshold values for steels of similar sulfur content but varying sulfide morphology is observed. The threshold velocity decreases with the increasing maximum sulfide particle size, qualitatively consistent with the theory. The calculation provides a basis for a conservative minimum velocity threshold tied directly to the steel sulfur level, in cases where no details of sulfide distribution are known

Mean Stress and Environmental Effects on Fatigue in Type 304 Stainless Steel

Fatigue life tests were performed in air on Type 304 stainless steel (304 SS) to establish the effect of mean stress under both load control and strain control. An apparent reduction of up to 26% in strain-amplitude occurred in the low and intermediate cycle regime (< 10{sup 8} cycles) for a mean stress of 138 Mpa. A quantitative description of mean stress effects using the Smith-Watson-Topper equivalent strain parameter was developed, which incorporates mean stress through the maximum stress. This description provided a tighter fit to the data, and allowed separation of mean stress and cold work effects. With this separation, the effect of mean stress was reduced to 12% decrease in strain amplitude at 138 Mpa. The stress-life curve apparently increased with increasing mean stress, due to the significant work hardening that occurred in tests with high mean stresses, especially under load control. Tests were performed on double-edge notched specimens of 304 SS in air and low oxygen water at 288 C. The elastically calculated increase in the notch tip stress accounted within 10% for the fatigue life reductions for a K{sub t} = 4.8 notch, but was 38% conservative for a K{sub t} = 8.8 notch. Fatigue crack initiation lives (defined as an 0.127 mm crack) in low oxygen water at 288 C were reduced by a factor of four to eight on cycles over those in air. Crack growth occurred throughout most of the fatigue ''initiation'' life. The increase in crack growth rate of 304 SS in water appears to be large enough to explain the reduced ''initiation'' life in this environment