1,160 research outputs found
Stable oxygen and carbon isotope compositional fields for skeletal and diagenetic components in New Zealand Cenozoic nontropical carbonate sediments and limestones: a synthesis and review
The stable oxygen isotope composition (dĀ¹āøO) of a precipitated carbonate depends mainly on the isotope composition, salinity, and temperature of the host fluid, whereas the stable carbon isotope composition (dĀ¹Ā³C) reflects the source of CO2 for precipitation, such as meteoric or sea water, shell dissolution, or various biochemical origins, including microbial oxidation of organic matter and methane. Despite the potentially complex array of controls, natural waters tend to show a characteristic range of isotope values which in turn are mimicked or tracked by the carbonate minerals precipitated from them. Consequently, plots of dĀ¹āøO versus dĀ¹Ā³C for carbonate materials can help identify their depositional and/or diagenetic environment(s)
Mineralogical Variation in Shells of the Blackfoot Abalone, Haliotis iris (Mollusca: Gastropoda: Haliotidae), in Southern New Zealand
The New Zealand blackfoot abalone, Haliotis iris Gmelin, is among
the few gastropods that precipitate both calcite and aragonite in their shells. The
location, composition, and thickness of these mineral layers may affect color,
luster, and strength of the shell, which is locally important in jewelry manufacture.
Skeletal mineralogy and shell structure of H. iris from three southern
New Zealand locations were determined using X-ray diffractometry, scanning
electron micrography, and mineral staining. In H. iris an outer calcitic layer is
separated from an inner aragonitic surface by both calcified and noncalcified
organic layers running longitudinally through the shell. Skeletal mineralogy
within individual shells varies from 29 to 98% aragonite, with older shell having
significantly higher aragonite content than young sections. Variation within
populations ranges from 40 to 98% aragonite, and among three populations
from 34 to 98% aragonite. Shell thickness, too, varies within individual shells
from 0.2 to 4.2 mm, with a significant positive relationship with age. Within population
variation in shell thickness ranges from 2.1 to 5.4 mm, with no
significant difference in shell thickness variation among populations. The high
degree of variability within and among individual shells suggests that it is
essential to test replicate samples from individual mollusk shells, especially when
they have complex bimineral structure
Non-Traditional and Non-Invasive Approaches in Facial Rejuvenation: A Brief Review
While injectables, lasers, and surgical interventions have traditionally been used to reverse the changes associated with facial aging, other alternative therapies such as facial acupuncture and facial exercises are now being studied for facial rejuvenation. In this paper, we both summarize the concepts of facial acupuncture and facial exercises, and review seven studies that evaluate the efficacy of these modalities. Data from these studies suggest that both facial acupuncture and facial exercises have the potential to improve the skin laxity, wrinkle length, muscle thickness, and pigmentary changes associated with aging. Patients frequently reported improvement and experienced very few side effects. However, further research is necessary before these modalities are widely accepted as eective by the medical community, though the results of these studies may ultimately make providers less hesitant when patients seek out these services
Non-Traditional and Non-Invasive Approaches in Facial Rejuvenation: A Brief Review
While injectables, lasers, and surgical interventions have traditionally been used to reverse the changes associated with facial aging, other alternative therapies such as facial acupuncture and facial exercises are now being studied for facial rejuvenation. In this paper, we both summarize the concepts of facial acupuncture and facial exercises, and review seven studies that evaluate the efficacy of these modalities. Data from these studies suggest that both facial acupuncture and facial exercises have the potential to improve the skin laxity, wrinkle length, muscle thickness, and pigmentary changes associated with aging. Patients frequently reported improvement and experienced very few side effects. However, further research is necessary before these modalities are widely accepted as effective by the medical community, though the results of these studies may ultimately make providers less hesitant when patients seek out these services
Benefactors, Bonds, and Beholders: The Beliefs and Reality Behind Beethovenās Behavior
This paper will explore the relationships which Beethoven had during the years he composed and premiered his Eroica Symphony. Some of the individuals who will be discussed in this paper include Prince Lobkowitz, Ferdinand Ries, and Franz Wegeler. After learning about the nature of these relationships, the reader should begin to realize that Beethovenās notoriously irrational or ill-tempered behavior was only one facet of his life
Sulfate Enhances the Adsorption and Retention of Cu(II) and Zn(II) to Dispersed and Aggregated Iron Oxyhydroxide Nanoparticles
The adsorption and retention of metal ions to nanoscale iron (hydr)oxides in aqueous systems is significantly influenced by prevailing environmental conditions. We examined the influence of sulfate, the second most common anion in seawater that is present in many other natural aquatic systems, on the adsorption and retention of Cu(II) and Zn(II) to synthetic iron oxyhydroxide nanoparticles (NPs) and their aggregates. Batch uptake experiments with monodisperse NPs and NPs aggregated by changes in pH, ionic strength, and temperature were conducted over sulfate concentrations ranging from 0 to 0.30 M. The introduction of 0.03 M sulfate significantly increased the initial adsorption and retention of Zn(II) and Cu(II) compared to sulfate-free conditions; with increasing sulfate \u3e0.03 M, Zn(II) retention continuously increased, while Cu(II) retention was considerably more variable but increased slightly. NP aggregation, when induced by pH and ionic strength, was positively correlated with metal ion retention, while aggregation temperature was negatively correlated with both adsorption and retention. Aqueous geochemical modeling indicated that Zn(II) readily complexes with sulfate to form ZnSO4 (aq), but that stable aqueous CuSO4 species are uncommon. EXAFS spectroscopic analysis suggests structural incorporation of Zn(II) and Zn(II)-sulfate ternary surface complexation, while Cu(II) primarily forms inner-sphere bidentate surface complexes. Collectively, the effects of sulfate in both reducing surface charge repulsion, initiating ternary surface complexation, and enabling structural incorporation aid to enhance both metal adsorption and retention to iron oxyhydroxide NPs and their aggregates
An Up-Close Look at Student-Centered Math Teaching: A Study of Highly Regarded High School Teachers and Their Students - Executive Summary
Today, far too many students see mathematics as a subject to be endured, rather than a subject of real-world importance and personal value. That doesn't have to be the case. When teachers use student-centered techniques to engage studentsin more active and authentic ways, they can transform math classrooms into lively learning environments in which studentstake charge of their own learning, collaborate with others, persist in solving complex problems, and make meaningfulconnections to the world around them. Through such experiences, students may come to appreciate mathematics as adiscipline that enriches their lives and their understanding of the world.While a growing body of research supports many of the principles of student-centered instruction, there is still a great dealto learn about how such approaches enhance student learning in mathematics. Recent calls for strengthening the STEMworkforce and for more rigorous K-12 standards via the Common Core State Standards have placed increased emphasison developing higher-order thinking and problem-solving skills in high school mathematics, heightening the need for moreinformation about how teachers can effectively engage students with math content.The American Institutes of Research (AIR), with support from the Nellie Mae Education Foundation, conducted a study ofhighly regarded high school math teachers to expand the research base in two important ways. First, rather than assumingstudent-centered instruction is a monolithic construct, the team used a case study approach to provide rich descriptions ofhow the approach plays out in several classrooms, taking into account how teachers' personal philosophy and the school'sinstructional context might influence their practice. The case study also provided insights into students' perspectives on different approaches to mathematics instruction. Second, the researchers look across a larger sample of classrooms to determine the effects of varying degrees of student-centeredness on students' engagement with learning and their problem-solving skills.This brief offers highlights from the study's design and findings. Readers are encouraged to access the full paper for more details
The impact of believing you have had COVID-19 on self-reported behaviour: Cross-sectional survey.
OBJECTIVES: To investigate whether people who think they have had COVID-19 are less likely to report engaging with lockdown measures compared with those who think they have not had COVID-19. DESIGN: On-line cross-sectional survey. SETTING: Data were collected between 20th and 22nd April 2020. PARTICIPANTS: 6149 participants living in the UK aged 18 years or over. MAIN OUTCOME MEASURES: Perceived immunity to COVID-19, self-reported adherence to social distancing measures (going out for essential shopping, nonessential shopping, and meeting up with friends/family; total out-of-home activity), worry about COVID-19 and perceived risk of COVID-19 to oneself and people in the UK. Knowledge that cough and high temperature / fever are the main symptoms of COVID-19. We used logistic regression analyses and one-way ANOVAs to investigate associations between believing you had had COVID-19 and binary and continuous outcomes respectively. RESULTS: In this sample, 1493 people (24.3%) thought they had had COVID-19 but only 245 (4.0%) reported having received a positive test result. Reported test results were often incongruent with participants' belief that they had had COVID-19. People who believed that they had had COVID-19 were: more likely to agree that they had some immunity to COVID-19; less likely to report adhering to lockdown measures; less worried about COVID-19; and less likely to know that cough and high temperature / fever are two of the most common symptoms of COVID-19. CONCLUSIONS: At the time of data collection, the percentage of people in the UK who thought they had already had COVID-19 was about twice the estimated infection rate. Those who believed they had had COVID-19 were more likely to report leaving home. This may contribute to transmission of the virus. Clear communications to this growing group are needed to explain why protective measures continue to be important and to encourage sustained adherence
Identifying Farming Strategies Associated With Achieving Global Agricultural Sustainability
Sustainable agroecosystems provide adequate food while supporting environmental and human wellbeing and are a key part of the United Nations Sustainable Development Goals (SDGs). Some strategies to promote sustainability include reducing inputs, substituting conventional crops with genetically modified (GM) alternatives, and using organic production. Here, we leveraged global databases covering 121 countries to determine which farming strategiesāthe amount of inputs per area (fertilizers, pesticides, and irrigation), GM crops, and percent agriculture in organic productionāare most correlated with 12 sustainability metrics recognized by the United Nations Food and Agriculture Organization. Using quantile regression, we found that countries with higher Human Development Indices (HDI) (including education, income, and lifespan), higher-income equality, lower food insecurity, and higher cereal yields had the most organic production and inputs. However, input-intensive strategies were associated with greater agricultural greenhouse gas emissions. In contrast, countries with more GM crops were last on track to meeting the SDG of reduced inequalities. Using a longitudinal analysis spanning 2004ā2018, we found that countries were generally decreasing inputs and increasing their share of agriculture in organic production. Also, in disentangling correlation vs. causation, we hypothesize that a country's development is more likely to drive changes in agricultural strategies than vice versa. Altogether, our correlative analyses suggest that countries with greater progress toward the SDGs of no poverty, zero hunger, good health and wellbeing, quality education, decent work, economic growth, and reduced inequalities had the highest production of organic agriculture and, to a lesser extent, intensive use of inputs
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Arctic Sea Ice in Two Configurations of the CESM2 During the 20th and 21st Centuries
We provide an assessment of the current and future states of Arctic sea ice simulated by the Community Earth System Model version 2 (CESM2). The CESM2 is the version of the CESM contributed to the sixth phase of the Coupled Model Intercomparison Project (CMIP6). We analyze changes in Arctic sea ice cover in two CESM2 configurations with differing atmospheric components: the CESM2(CAM6) and the CESM2(WACCM6). Over the historical period, the CESM2(CAM6) winter ice thickness distribution is biased thin, which leads to lower summer ice area compared to CESM2(WACCM6) and observations. In both CESM2 configurations, the timing of first iceāfree conditions is insensitive to the choice of CMIP6 future emissions scenario. In fact, the probability of an iceāfree Arctic summer remains low only if global warming stays below 1.5°C, which none of the CMIP6 scenarios achieve. By the end of the 21st century, the CESM2 simulates less ocean heat loss during the fall months compared to its previous version, delaying sea ice formation and leading to iceāfree conditions for up to 8 months under the high emissions scenario. As a result, both CESM2 configurations exhibit an accelerated decline in winter and spring ice area, a behavior that had not been previously seen in CESM simulations. Differences in climate sensitivity and higher levels of atmospheric CO2 by 2100 in the CMIP6 high emissions scenario compared to its CMIP5 analog could explain why this winter ice loss was not previously simulated by the CESM. Plain Language Summary We provide a first look at the current and future states of Arctic sea ice as simulated by the Community Earth System Model version 2 (CESM2), which is part of the newest generation of largeāscale climate models. The CESM2 model has two configurations that differ in their representation of atmospheric processes: the CESM2(CAM6) and the CESM2(WACCM6). We find several differences in the simulated Arctic sea ice cover between the two CESM2 configurations, as well as compared to the previous generation of the CESM model. Over the historical period, the CESM2(CAM6) model simulates a winter ice cover that is too thin, which leads to lower summer ice coverage compared to the CESM2(WACCM6) model and observations. In both CESM2 configurations, the probability of the Arctic becoming nearly ice free at the end of the summer remains low only if global warming stays below 1.5°C. In addition, the specific year a first iceāfree Arctic is reached is not sensitive to the future greenhouse gas emissions trajectories considered here. In contrast to the previous generation of the CESM, both CESM2 configurations project an accelerated decline in winter and spring ice area by the end of the 21st century if greenhouse gases emissions remain high. Key Points The CESM2(CAM6) winter ice thickness distribution is biased thin and leads to a lower summer sea ice area than observed The timing of first Arctic iceāfree conditions in the CESM2 is independent of the choice of CMIP6 future emissions scenario By 2100, CESM2 shows an accelerated decline in winter and spring area under the high emissions scenario due to reduced fall ocean heat loss</p
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