Explore the vast range of titles available.

The endoskeletal structure of the Sea Urchin, Centrostephanus rodgersii, has numerous long spines whose known functions include locomotion, sensing, and protection against predators. These spines have a remarkable internal microstructure and are made of single-crystal calcite. A finite-element model of the spine's unique porous structure, based on micro-computed tomography (microCT) and incorporating anisotropic material properties, was developed to study its response to mechanical loading. Simulations show that high stress concentrations occur at certain points in the spine's architecture; brittle cracking would likely initiate in these regions. These analyses demonstrate that the organization of single-crystal calcite in the unique, intricate morphology of the sea urchin spine results in a strong, stiff and lightweight structure that enhances its strength despite the brittleness of its constituent material.

Emeryville, California’s Fair Workweek Ordinance (FWO) aimed to reduce service workers’ schedule unpredictability by requiring large retail and food service employers to provide advanced notice of schedules and to compensate workers for last-minute schedule changes. From ninety-six workers with young children (N = 78 in longitudinal analyses; 58 percent working in regulated businesses at baseline), this study gathered daily reports of work schedule unpredictability and worker and family well-being over three waves before and after FWO implementation. The FWO decreased working parents’ schedule unpredictability and improved their well-being relative to those in similar jobs at unregulated establishments. The FWO also decreased parents’ days worked while increasing hours per work day, leaving total hours roughly unchanged. Finally, parent well-being improved and declines in sleep difficulty were significant.

Crystal defects form during tectonic deformation and are reactivated by the shear stress associated with passing seismic waves. Although these defects, known as dislocations, potentially contribute to the attenuation of seismic waves in Earth's upper mantle, evidence for dislocation damping from laboratory studies has been circumstantial. We experimentally determined the shear modulus and associated strain-energy dissipation in pre-deformed synthetic olivine aggregates under high pressures and temperatures. Enhanced high-temperature background dissipation occurred in specimens pre-deformed by dislocation creep in either compression or torsion, the enhancement being greater for prior deformation in torsion. These observations suggest the possibility of anisotropic attenuation in relatively coarse-grained rocks where olivine is or was deformed at relatively high stress by dislocation creep in Earth's upper mantle.

Eight feldspar phases have been distinguished within individual alkali feldspar primocrysts in laminated syenite members of the layered syenite series of the Klokken intrusion. The processes leading to the formation of the first four phases have been described previously. The feldspars crystallized as homogeneous sodian sanidine and exsolved by spinodal decomposition, between 750 and 600 °C, depending on bulk composition, to give fully coherent, strain-controlled braid cryptoperthites with sub-μm periodicities. Below ~500 °C, in the microcline field, these underwent a process of partial mutual replacement in a deuteric fluid, producing coarse (up to mm scale), turbid, incoherent patch perthites. We here describe exsolution and replacement processes that occurred after patch perthite formation. Both Or- and Ab-rich patches underwent a new phase of coherent exsolution by volume diffusion. Or-rich patches began to exsolve albite lamellae by coherent nucleation in the range 460–340 °C, depending on patch composition, leading to film perthite with ≤1 μm periodicities. Below ~300 °C, misfit dislocation loops formed, which were subsequently enlarged to nanotunnels. Ab-rich patches (bulk composition ~Ab 91 Or 1 An 8 ), in one sample, exsolved giving peristerite, with one strong modulation with a periodicity of ~17 nm and a pervasive tweed microtexture. The Ab-rich patches formed with metastable disorder below the peristerite solvus and intersected the peristerite conditional spinodal at ~450 °C. This is the first time peristerite has been imaged using TEM within any perthite, and the first time peristerite has been found in a relatively rapidly cooled geological environment. The lamellar periodicities of film perthite and peristerite are consistent with experimentally determined diffusion coefficients and a calculated cooling history of the intrusion. All the preceding textures were in places affected by a phase of replacement correlating with regions of extreme optical turbidity. We term this material ultra porous late feldspar (UPLF). It is composed predominantly of regions of microporous very Or-rich feldspar (mean Ab 2.5 Or 97.4 An 0.1 ) associated with very pure porous albite (Ab 97.0 Or 1.6 An 1.4 ) implying replacement below 170–90 °C, depending on degree of order. In TEM, UPLF has complex, irregular diffraction contrast similar to that previously associated with low-temperature albitization and diagenetic overgrowths. Replacement by UPLF seems to have been piecemeal in character. Ghost-like textural pseudomorphs of both braid and film parents occur. Formation of patch perthite, film perthite and peristerite occurred 10 4 –10 5 year after emplacement, but there are no microtextural constraints on the age of UPLF formation.

Research demonstrates that receiving unemployment insurance decreases mental health problems. But researchers have also found racial and ethnic disparities in unemployment insurance receipt resulting from differences in work history and location. We examined a population disproportionately affected by job loss and unemployment insurance exclusions, using a survey of service workers from a single city who were parents of young children and who overwhelmingly had eligible work histories. During the COVID-19 pandemic, workers not identifying as White non-Hispanic in our sample were more likely to get laid off than White workers. Among those who were laid off, these workers and White workers experienced similar increases in material and mental health difficulties and similar gains when they received unemployment insurance. However, these workers were less likely than White workers to receive unemployment insurance at all. These results indicate that unemployment insurance has unrealized potential to reduce material and health disparities. Policies should be implemented to make this coverage more effective and equitable through increased access.

Microtextural changes brought about by heating alkali feldspar crystals from the Shap granite, northern England, at atmospheric pressure, have been studied using transmission and scanning electron microscopy. A typical unheated phenocryst from Shap is composed of about 70 vol% of tweed orthoclase with strain-controlled coherent or semicoherent micro- and crypto-perthitic albite lamellae, with maximum lamellar thicknesses <1 μm. Semicoherent lamellae are encircled by nanotunnel loops in two orientations and cut by pull-apart cracks. The average bulk composition of this microtexture is Ab 27.6 Or 71.8 An 0.6 . The remaining 30 vol% is deuterically coarsened, microporous patch and vein perthite composed of incoherent subgrains of oligoclase, albite and irregular microcline. The largest subgrains are ~3 μm in diameter. Heating times in the laboratory were 12 to 6,792 h and T from 300°C into the melting interval at 1,100°C. Most samples were annealed at constant T but two were heated to simulate an 40 Ar/ 39 Ar step-heating schedule. Homogenisation of strain-controlled lamellae by Na↔K inter-diffusion was rapid, so that in all run products at >700°C, and after >48 h at 700°C, all such regions were essentially compositionally homogeneous, as indicated by X-ray analyses at fine scale in the transmission electron microscope. Changes in lamellar thickness with time at different T point to an activation energy of ~350 kJmol −1 . A lamella which homogenised after 6,800 h at 600°C, therefore, would have required only 0.6 s to do so in the melting interval at 1,100°C. Subgrains in patch perthite homogenised more slowly than coherent lamellae and chemical gradients in patches persisted for >5,000 h at 700°C. Homogenisation T is in agreement with experimentally determined solvi for coherent ordered intergrowths, when a 50–100°C increase in T for An 1 is applied. Homogenisation of lamellae appears to proceed in an unexpected manner: two smooth interfaces, microstructurally sharp, advance from the original interfaces toward the mid-line of each twinned, semicoherent lamella. In places, the homogenisation interfaces have shapes reflecting the local arrangements of nanotunnels or pull-aparts. Analyses confirm that the change in alkali composition is also relatively sharp at these interfaces. Si–Al disordering is far slower than alkali homogenisation so that tweed texture in orthoclase, tartan twinning in irregular microcline, and Albite twins in albite lamellae and patches persisted in all our experiments, including 5,478 h at 700°C, 148 h at 1,000°C and 5 h at 1,100°C, even though the ensemble in each case was chemically homogeneous. Nanotunnels and pull-aparts were modified after only 50 min at 500°C following the simulated 40 Ar/ 39 Ar step-heating schedule. New features called ‘slots’ developed away from albite lamellae, often with planar traces linking slots to the closest lamella. Slot arrays were often aligned along ghost-like regions of diffraction contrast which may mark the original edges of lamellae. We suggest that the slot arrays result from healing of pull-aparts containing fluid. At 700°C and above, the dominant defects were subspherical ‘bubbles’, which evolved from slots or from regions of deuteric coarsening. The small degree of partial melting observed after 5 h at 1,100°C was often in the vicinity of bubbles. Larger micropores, which formed at subgrain boundaries in patch perthite during deuteric coarsening, retain their shape up to the melting point, as do the subgrain boundaries themselves. It is clear that modification of defects providing potential fast pathways for diffusion in granitic alkali feldspars begins below 500°C and that defect character progressively changes up to, and beyond, the onset of melting.

The partial breakdown of Ti-chondrodite and Ti-clinohumite during exhumation from ultra-high pressure to amphibolite facies conditions in garnet-pyroxenites from Dabie Shan (China) produces coronas of olivine coexisting with ilmenite blebs. Fourier transform infrared (FTIR) spectra of this newly formed olivine exhibit absorption bands in the hydroxyl-stretching region. Two intense peaks were observed at 3,564 and 3,394 cm-1, identical in energy to peaks in Ti-clinohumite. Transmission electron microscopy (TEM) of the same olivine domains revealed the presence of a complex (001) planar intergrowth. These interlayers have a 1.35 nm repeat distance, which is characteristic of clinohumite. Such interlayers are also enriched in Ti with respect to the adjacent olivine as shown by energy dispersive spectrometry. The combined evidence from FTIR spectroscopy and TEM indicates that OH is incorporated along Ti-clinohumite planar defects. This study provides evidence that the nominally anhydrous phase olivine may contain OH as a humite-type defect beyond the breakdown of the hydrous humite minerals and confirms earlier suggestions that Ti plays a key role in OH incorporation in mantle olivine. We suggest that olivine containing Ti-clinohumite defects is an important phase for water transport in subduction zones and for the storage of water in cold subcontinental mantle. However, these defects are unlikely to be stable in hotter parts of the oceanic mantle such as where basaltic magmas are generated. [PUBLICATION ABSTRACT]

With the advent of EMU, monetary policy can no longer be used to prevent housing market bubbles in regional economies such as Ireland or Spain. However, fiscal policy can and should be used to achieve the same effect. This paper shows that the advent of EMU relaxed existing financial constraints in Ireland and Spain, allowing a more rapid expansion of the housing stock in those countries to meet their specific demographic circumstances. However, the failure to prevent these booms turning into bubbles did lasting damage to the two economies, damage that could have been avoided by more appropriate fiscal policy action.

This book takes a theoretically informed look at British education policy over the last sixty years when secondary schooling for all children became an established fact for the first time. Comprehensive schools largely replaced a system based on academic selection. Now, under choice and competition policies, all schools are subject to the rigours of local education markets. What impact did each of these successive policy frameworks have on structures of opportunities for families and their children? How and to what extent was the experience of secondary school students shaped and what influenced the qualifications they obtained and their life chances after schooling? The authors locate their work within two broad strands in the sociology of education. Basil Bernstein’s work on the realisation of power and control in and through pedagogic discourse and social reproduction provides a theoretical framework for exploring the character of and continuities and change in education and training policies. The book is an important contribution to debates about the extent to which education is a force for change in class divided societies. The authors also set out to re-establish social class at the centre of educational analysis at a time when emphasis has been on identity and identity formation, arguing for their interdependence. This book will be an important resource for students, policy analysts and policymakers wishing to think through and understand the longer term impact of programmes that have shaped secondary schooling in Britain and elsewhere. 1. Understanding policy, understanding pedagogic discourse Introduction Bernstein’s sociology, a language for policy On our omissions 2. Framing Equality? The Education Act 1944 Introduction Policy frameworks The 1944 legislation A governing partnership? Tripartism: a very British settlement? Conclusions 3. Selection, class and opportunity Introduction Selection and social class Selection and social class and school composition Greater equality of opportunity? Whatever Happened To The Likely Lads? Conclusions 4. Comprehensive schooling: Challenging inequality ? Introduction Going comprehensive from the ground up What was driving the change? 10/65 and after: Comprehensive Schooling and its challenges Neighbourhoods and differentiation between schools Conclusions 5. Educational Systems and Social Mobility Social mobility and education Social mobility, selection and comprehensivisation Social Mobility, Meritocracy and Education Conclusion 6. Bernstein, social reproduction and intergenerational transmission Introduction Pedagogic discourse; family, school and work Pedagogic discourse, policy and reproduction Pedagogic discourse: its key features Sifting and Sorting Privileging practices Resources Conclusions 7. Something happened: the policy framework post 1988 Introduction Centralisation: reasserting central authority, putting on the pressure Choice and diversity: power to parents? Conclusion 8. Diversity: selection and stratification? Introduction From diversity to plurality ‘New’ Labour and school diversity The Early Years Specialist Schools Academies Beacon Schools and Leading Edge Partnerships Federations and Diversity Pathfinders Faith-based schools The modernisation of comprehensive schools School diversity and social equity Conclusions 9. Further reading Bibliography