One size doesn't fit all: Research methodologies in a language variation study of Sudanese teens

The research reported here draws on a study of five teenagers from a Dinka-speaking community of Sudanese settling in Australia. A range of factors including language proficiency, social network structure and language attitudes are examined as possible causes for the variability of language use. The results and discussion illustrate how the use of a triangular research approach captured the complexity of the participants' language situation and was critical to developing a full understanding of the interplay of factors influencing the teens' language maintenance and shift in a way that no single method could. Further, it shows that employment of different methodologies allowed for flexibility in data collection to ensure the fullest response from participants. Overall, this research suggests that for studies of non-standard communities, variability in research methods may prove more of a strength that the use of standardised instruments and approaches

High-frequency fluctuations in redox conditions during the latest Permian mass extinction

This study was supported financially by NERC Fellowship NE/H016805/2 (to AZ), NERC Standard Grant NE/J023485/2 (to AZ and MC), NSFEAR-1455258 (to CJK). Samples were collected by RJT, who thanks G. Cuny and the Danish National Research Foundation for logistics and financial support.New high-resolution geochemical and sedimentological data from Fiskegrav, East Greenland, reveal fluctuations in marine redox conditions associated with the final disappearance of bioturbating organisms during the latest Permian mass extinction (LPME). Sedimentological observations imply a transgressive episode, and associated geochemical evidence for decreasing oxygen availability and the establishment of persistently ferruginous (Fe2 +-rich) conditions implies the shoreward migration of oxygen deficient waters. The long-term decline in dissolved oxygen (DO) availability could have been exacerbated by increasing water temperatures, reducing the solubility of oxygen and promoting thermal stratification. Mixing of the water column could have been further inhibited by freshwater influxes that could have generated salinity contrasts that reinforced thermal stratification. Enhanced runoff could also have increased the delivery of nutrients to the marine shelf, stimulating biological oxygen demand (BOD). During the transition to persistently ferruginous conditions we identify intervals of intermittent benthic meiofaunal recolonization, events that we attribute to small transient increases in DO availability. The mechanism controlling these fluctuations remains speculative, but given the possible centennial- to millennial-scale frequency of these changes, we hypothesise that the mid-latitude setting of Fiskegrav during the Late Permian was sensitive to changes in atmospheric circulation patterns, which may have influenced local precipitation and intermittently modulated some of the processes promoting anoxia.Publisher PDFPeer reviewe

Biological Regulation of Atmospheric Chemistry En Route to Planetary Oxygenation

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ∼2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions—featuring a methane-derived organic-haze—have recently been suggested, yet their occurrence, causes, and significance remain underexplored. To examine the role of haze formation in Earth’s history, we targeted an episode of inferred haze development. Our redox-controlled (Fe-speciation) carbon- and sulfur-isotope record reveals sustained systematic stratigraphic covariance, precluding nonatmospheric explanations. Photochemical models corroborate this inference, showing Δ³⁶S/Δ³³S ratios are sensitive to the presence of haze. Exploiting existing age constraints, we estimate that organic haze developed rapidly, stabilizing within ∼0.3 ± 0.1 million years (Myr), and persisted for upward of ∼1.4 ± 0.4 Myr. Given these temporal constraints, and the elevated atmospheric CO₂ concentrations in the Archean, the sustained methane fluxes necessary for haze formation can only be reconciled with a biological source. Correlative δ¹³C₀rg and total organic carbon measurements support the interpretation that atmospheric haze was a transient response of the biosphere to increased nutrient availability, with methane fluxes controlled by the relative availability of organic carbon and sulfate. Elevated atmospheric methane concentrations during haze episodes would have expedited planetary hydrogen loss, with a single episode of haze development providing up to 2.6–18 × 10¹⁸ moles of O₂ equivalents to the Earth system. Our findings suggest the Neoarchean likely represented a unique state of the Earth system where haze development played a pivotal role in planetary oxidation, hastening the contingent biological innovations that followed

Nitrogen fixation sustained productivity in the wake of the Palaeoproterozoic Great Oxygenation Event

The marine nitrogen cycle is dominated by redox-controlled biogeochemical processes and, therefore, is likely to have been revolutionised in response to Earth-surface oxygenation. The details, timing, and trajectory of nitrogen cycle evolution, however, remain elusive. Here we couple nitrogen and carbon isotope records from multiple drillcores through the Rooihoogte-Timeball Hill Formations from across the Carletonville area of the Kaapvaal Craton where the Great Oxygenation Event (GOE) and its aftermath are recorded. Our data reveal that aerobic nitrogen cycling, featuring metabolisms involving nitrogen oxyanions, was well established prior to the GOE and that ammonium may have dominated the dissolved nitrogen inventory. Pronounced signals of diazotrophy imply a stepwise evolution, with a temporary intermediate stage where both ammonium and nitrate may have been scarce. We suggest that the emergence of the modern nitrogen cycle, with metabolic processes that approximate their contemporary balance, was retarded by low environmental oxygen availability.National Science Foundation (U.S.) (Grant EAR-1338810)National Science Foundation (U.S.) (Grant EAR-1455258

VALUING CHANGES IN THE PROVISION OF A PUBLIC GOOD: EMPIRICAL APPLICATIONS IN ENVIRONMENTAL AND HEALTH ECONOMICS

This work applies revealed and stated preference methods for valuing changes in the provision of environmental and health care goods. It estimates non-market benefits to society from protecting forest lands from commercial activities and elicits individuals preference (e.g., willingness to pay) for expanding health care coverage to the uninsured. Health care provision policies can save lives but also increase costs, and may work best when done in combination with behavioral and health interventions that promote healthy life styles such as protecting public forest lands. Chapters 2 and 3 apply the hedonic pricing empirical framework to investigate whether protecting public forest lands generate economic values that capitalize in the labor and housing market. Chapter 2 investigates the role of natural amenities, in the form of Inventoried Roadless Areas (IRAs), in the Southwest United States (US). IRAs are defined as Public Forest or Grasslands exceeding 5,000 acres that are undeveloped areas with little or no timber harvest and no human construction (USDA 2001a). In light of the current legal debate over whether to open IRAs to commercial activities or to maintain them in their pristine status, a better understanding is needed about the values that these lands in particular may have within a regional economic context, as observed in housing and labor markets. Based on this motivation, these chapters distinguish between congressionally-protected lands also called wilderness areas, IRAs, and the all inclusive open space definition of a public land (e.g., public forest areas in the National Forest System) to estimate the implicit values that individuals have for these lands (e.g., off-site benefits). After accounting for the presence of spatial dependence (e.g., spatial lag and spatial error models) these chapters show significant off-site benefits for living in proximity or in areas with high percentage of IRAs. Scale and zoning effects (e.g., ecological fallacy, Doll et al. 2004) due to the aggregation of data into predefined administrative boundaries (such as Census tracts) are addressed in chapter 3 by using micro-data with a sample of matched wage-earner housing units. Chapter 4 uses survey-based data to address changes the in provision of a different good with public attributes: expanding health care coverage to the uninsured in New Mexico. One year after Affordable Care Act (ACA) became law public support for such a reform is still significantly divided (42% in favor and 46% against, The Kaiser Family Foundation, 2011). Given the desire to provide universal health coverage but the reluctance to pay higher taxes at the national level, would a state-based reform receive a majority support from New Mexicans? While New Mexican may widely express support for health care reform, they may be collectively and politically unwilling to finance expansion to all the uninsured, with either higher taxes or increased premiums. As such, the results also suggest that an incremental approach, in the search for majority support (and presumably more political support), might be to expand health care coverage to specific segments of the population such as individuals with chronic conditions

Molecular Genetics of T Cell Development

T cell development is guided by a complex set of transcription factors that act recursively, in different combinations, at each of the developmental choice points from T-lineage specification to peripheral T cell specialization. This review describes the modes of action of the major T-lineage-defining transcription factors and the signal pathways that activate them during intrathymic differentiation from pluripotent precursors. Roles of Notch and its effector RBPSuh (CSL), GATA-3, E2A/HEB and Id proteins, c-Myb, TCF-1, and members of the Runx, Ets, and Ikaros families are critical. Less known transcription factors that are newly recognized as being required for T cell development at particular checkpoints are also described. The transcriptional regulation of T cell development is contrasted with that of B cell development, in terms of their different degrees of overlap with the stem-cell program and the different roles of key transcription factors in gene regulatory networks leading to lineage commitment

The Effect of Pangasius hypopthalmus Oil on the Memory of Mice (Mus musculus)

Fish oil is an essential nutrient that is vital for the human body due to its content of saturated and unsaturated fatty acids, particularly omega-3. The Pangasius fish (Pangasius hypopthalmus) is known to have a relatively high content of omega-3 compared to other freshwater fish. Omega-3 fatty acids are crucial for neuronal growth, thereby influencing memory function. This study aimed to investigate the effect of Pangasius fish oil on the memory of mice (Mus musculus). The experimental design was a completely randomized design involving 24 mice, divided into six treatment groups (P0: Control, P1: 0.0016 ml/g weight/day, P2: 0.0033 ml/g weight/day, P3: 0.005 ml/g weight/day, P4: 0.0066 ml/g weight/day, P5: 0.0083 ml/g weight/day), with four repetitions for each treatment administered over seven days. The parameter observed was the number of mice that correctly explored all arms of the Y-maze. The observations indicated that fish oil has a tendency to influence the memory of mice

Notch ligation by Delta1 inhibits peripheral immune responses to transplantation antigens by a CD8⁺ cell–dependent mechanism

Notch signaling plays a fundamental role in determining the outcome of differentiation processes in many tissues. Notch signaling has been implicated in T versus B cell lineage commitment, thymic differentiation, and bone marrow hematopoietic precursor renewal and differentiation. Notch receptors and their ligands are also expressed on the surface of mature lymphocytes and APCs, but the effects of Notch signaling in the peripheral immune system remain poorly defined. The aim of the studies reported here was to investigate the effects of signaling through the Notch receptor using a ligand of the Delta-like family. We show that Notch ligation in the mature immune system markedly decreases responses to transplantation antigens. Constitutive expression of Delta-like 1 on alloantigen-bearing cells renders them nonimmunogenic and able to induce specific unresponsiveness to a challenge with the same alloantigen, even in the form of a cardiac allograft. These effects could be reversed by depletion of CD8⁺ cells at the time of transplantation. Ligation of Notch on splenic CD8⁺ cells results in a dramatic decrease in IFN-γ with a concomitant enhancement of IL-10 production, suggesting that Notch signaling can alter the differentiation potential of CD8⁺ cells. These data implicate Notch signaling in regulation of peripheral immunity and suggest a novel approach for manipulating deleterious immune responses