Low-temperature ordered phases of the spin-12\frac{1}{2} XXZ chain system Cs2_2CoCl4_4

In this study the magnetic order of the spin-1/2 XXZ chain system Cs$_2$CoCl$_4$ in a temperature range from 50 mK to 0.5 K and in applied magnetic fields up to 3.5 T is investigated by high-resolution measurements of the thermal expansion and the specific heat. Applying magnetic fields along a or c suppresses $T_\textrm{N}$ completely at about 2.1 T. In addition, we find an adjacent intermediate phase before the magnetization saturates close to 2.5 T. For magnetic fields applied along b, a surprisingly rich phase diagram arises. Two additional transitions are observed at critical fields $\mu_0 H_{SF1}\simeq 0.25$ T and $\mu_0 H_{SF2}\simeq 0.7$ T, which we propose to arise from a two-stage spin-flop transition.Comment: 10 pages, 10 figure

Symbiont 'bleaching' in planktic foraminifera during the Middle Eocene Climatic Optimum

Many genera of modern planktic foraminifera are adapted to nutrient-poor (oligotrophic) surface waters by hosting photosynthetic symbionts, but it is unknown how they will respond to future changes in ocean temperature and acidity. Here we show that ca. 40 Ma, some fossil photosymbiont-bearing planktic foraminifera were temporarily 'bleached' of their symbionts coincident with transient global warming during the Middle Eocene Climatic Optimum (MECO). At Ocean Drilling Program (ODP) Sites 748 and 1051 (Southern Ocean and mid-latitude North Atlantic, respectively), the typically positive relationship between the size of photosymbiont-bearing planktic foraminifer tests and their carbon isotope ratios (δ13C) was temporarily reduced for ∼100 k.y. during the peak of the MECO. At the same time, the typically photosymbiont-bearing planktic foraminifera Acarinina suffered transient reductions in test size and relative abundance, indicating ecological stress. The coincidence of minimum δ18O values and reduction in test size–δ13C gradients suggests a link between increased sea-surface temperatures and bleaching during the MECO, although changes in pH and nutrient availability may also have played a role. Our findings show that host-photosymbiont interactions are not constant through geological time, with implications for both the evolution of trophic strategies in marine plankton and the reliability of geochemical proxy records generated from symbiont-bearing planktic foraminifera

Kinetics of the Multiferroic Switching in MnWO4_4

The time dependence of switching multiferroic domains in MnWO$_4$ has been studied by time-resolved polarized neutron diffraction. Inverting an external electric field inverts the chiral magnetic component within rise times ranging between a few and some tens of milliseconds in perfect agreement with macroscopic techniques. There is no evidence for any faster process in the inversion of the chiral magnetic structure. The time dependence is well described by a temperature-dependent rise time suggesting a well-defined process of domain reversion. As expected, the rise times decrease when heating towards the upper boundary of the ferroelectric phase. However, switching also becomes faster upon cooling towards the lower boundary, which is associated with a first-order phase transition

Methodological Status and Trends in Expository Text Structure Instruction Efficacy Research

This systematic descriptive historical review was conducted to examine the status and trends in expository text structure instruction efficacy research for first through twelfth grade students. The analysis included sixty studies, which spanned the years 1978 to 2014. Descriptive dimensions of the research included study type, research design, treatment fidelity, school level, number of participants, service delivery settings, and comprehensiveness of demographic reporting, text structure instruction, and measurement. Researchers primarily used randomized and quasi-experimental research designs. Analysis of results revealed that (a) a relatively large number of text structure efficacy research studies have been conducted, (b) complete demographic information was difficult to ascertain for many of the participants, (c) researchers of few studies instructed students in all five expository text structures, (d) treatment fidelity data were often missing, and (e) researchers rarely used both direct and indirect measures of effects. Limitations of the analysis and future research directions are discussed

North Atlantic evidence for a for a unipolar icehouse climate state at the Eocene-Oligocene Transition

This is the final version. Available from Wiley via the DOI in this record.Earth’s climate transitioned from a warm unglaciated state to a colder glaciated ‘icehouse’ state during the Cenozoic. Extensive ice sheets were first sustained on Antarctica at the Eocene-Oligocene Transition (EOT, ~34 Ma), but there is intense debate over whether Northern Hemisphere ice sheets developed simultaneously at this time, or tens of millions of years later. Here we report on EOT-age sediments that contain detrital sand from Integrated Ocean Drilling Program (IODP) Sites U1406 and U1411 on the Newfoundland margin. These sites are ideally located to test competing hypotheses of the extent of Arctic glaciation, being situated in the North Atlantic’s 'iceberg alley' where icebergs, calved from both the Greenland Ice Sheet today, and the Laurentide Ice Sheet during the Pleistocene, are concentrated by the Labrador Current and deposit continentally-derived detritus. Here we show that detrital sand grains present in these EOT-aged sediments from the Newfoundland margin, initially interpreted to represent ice rafting, were sourced from the mid-latitudes of North America. We find that these grains were transported to the western North Atlantic by fluvial and downslope processes, not icebergs, and were subsequently reworked and deposited by deep-water contour currents on the Newfoundland margin. Our findings are inconsistent with the presence of extensive ice sheets on southern and western Greenland, and the northeastern Canadian Arctic. This contradicts extensive bipolar glaciation at the EOT. The unipolar icehouse arose because of contrasting latitudinal continental configurations at the poles, requiring more intense Cenozoic climatic deterioration to trigger extensive Northern Hemisphere glaciation.Royal Societ

Annual Feedback Is an Effective Tool for a Sustained Increase in Calcium Intake among Older Women

We aimed to optimize calcium intake among the 2,000+ older women taking part in the Vital D study. Calcium supplementation was not included in the study protocol. Our hypothesis was that annual feedback of calcium intake and informing women of strategies to improve calcium intake can lead to a sustained increase in the proportion of women who consume adequate levels of the mineral. Calcium intake was assessed on an annual basis using a validated short food frequency questionnaire (FFQ). Supplemental calcium intake was added to the dietary estimate. Participants and their nominated doctor were sent a letter that the participant’s estimated daily calcium intake was adequate or inadequate based on a cutoff threshold of 800 mg/day. General brief statements outlining the importance of an adequate calcium intake and bone health were included in all letters. At baseline, the median daily consumption of calcium was 980 mg/day and 67 percent of 1,951 participants had calcium intake of at least 800 mg per day. Of the 644 older women advised of an inadequate calcium intake at baseline (<800 mg/day), 386 (60%) had increased their intake by at least 100 mg/day when re-assessed twelve months later. This desirable change was sustained at 24 months after baseline with almost half of these women (303/644) consuming over 800 mg calcium per day. This study devised an efficient method to provide feedback on calcium intake to over 2,000 older women. The improvements were modest but significant and most apparent in those with a low intake at baseline. The decreased proportion of these women with an inadequate intake of calcium 12- and 24-months later, suggests this might be a practical, low cost strategy to maintain an adequate calcium intake among older women

Mechanical and optical properties of Lu2O3 host-ceramics for Ln(3+) lasants

Micro-hardness and fracture toughness, as well as linear optical properties (full transmission spectrum and refractive index dispersion) of fine-grained Lu2O3 ceramics fabricated by VSN method are presented