189 research outputs found
Critical thinking across the curriculum (CTAC)
Implementing critical thinking across the curriculum is challenging, involving securing substantial agreement on the nature of critical thinking, areas of prospective application (subject matter? everyday life?), degree of need for a separate course, and the nature of coordination, including leadership, a glossary, selection of courses for incorporation, avoidance of duplication and gaps, acquiring required subject matter, and assessment of the total effort, teaching methods used, and decrease or increase in retention of subject matter
Definition: A Three-Dimensional Analysis with Bearing on Key Concepts
This essay presents a three-dimensional analysis of definition (form, stance, and content) with application to making and evaluating definitions; teaching how to define; avoiding equivocation with argument and bias ; and, using the concept-conception distinction, avoiding being deterred by the many definitions of critical thinking , and seeing the usefulness of objectivity in everyday arguments in spite of existing conflict and confusion about aspects of objectivity
Correlation and causality
This paper provides an analysis of the argument from cause and effect and a comparison of its various types with the argument from correlation. It will be claimed that arguments from causality and from correlation should be treated as equivalent for argumentative purposes. The main advantages of this approach (theoretical economy and impact on the taxonomy of critical questions) as well as possible theo-retical objections will be discussed
Dengue Viral RNA Levels in Peripheral Blood Mononuclear Cells are Associated with Disease Severity and Preexisting Dengue Immune Status
Background
Infection with dengue viruses (DENV) causes a wide range of manifestations from asymptomatic infection to a febrile illness called dengue fever (DF), to dengue hemorrhagic fever (DHF). The in vivo targets of DENV and the relation between the viral burden in these cells and disease severity are not known. Method
The levels of positive and negative strand viral RNA in peripheral blood monocytes, T/NK cells, and B cells and in plasma of DF and DHF cases were measured by quantitative RT-PCR. Results
Positive strand viral RNA was detected in monocytes, T/NK cells and B cells with the highest amounts found in B cells. Viral RNA levels in CD14+ cells and plasma were significantly higher in DHF compared to DF, and in cases with a secondary infection compared to those undergoing a primary infection. The distribution of viral RNA among cell subpopulations was similar in DF and DHF cases. Small amounts of negative strand RNA were found in a few cases only. The severity of plasma leakage correlated with viral RNA levels in plasma and in CD14+ cells. Conclusions
B cells were the principal cells containing DENV RNA in peripheral blood, but overall there was little active DENV RNA replication detectable in peripheral blood mononuclear cells (PBMC). Secondary infection and DHF were associated with higher viral burden in PBMC populations, especially CD14+ monocytes, suggesting that viral infection of these cells may be involved in disease pathogenesis
Divergent controls of soil organic carbon between observations and process-based models
The storage and cycling of soil organic carbon (SOC) are governed by multiple co-varying factors, including climate, plant productivity, edaphic properties, and disturbance history. Yet, it remains unclear which of these factors are the dominant predictors of observed SOC stocks, globally and within biomes, and how the role of these predictors varies between observations and process-based models. Here we use global observations and an ensemble of soil biogeochemical models to quantify the emergent importance of key state factors – namely, mean annual temperature, net primary productivity, and soil mineralogy – in explaining biome- to global-scale variation in SOC stocks. We use a machine-learning approach to disentangle the role of covariates and elucidate individual relationships with SOC, without imposing expected relationships a priori. While we observe qualitatively similar relationships between SOC and covariates in observations and models, the magnitude and degree of non-linearity vary substantially among the models and observations. Models appear to overemphasize the importance of temperature and primary productivity (especially in forests and herbaceous biomes, respectively), while observations suggest a greater relative importance of soil minerals. This mismatch is also evident globally. However, we observe agreement between observations and model outputs in select individual biomes – namely, temperate deciduous forests and grasslands, which both show stronger relationships of SOC stocks with temperature and productivity, respectively. This approach highlights biomes with the largest uncertainty and mismatch with observations for targeted model improvements. Understanding the role of dominant SOC controls, and the discrepancies between models and observations, globally and across biomes, is essential for improving and validating process representations in soil and ecosystem models for projections under novel future conditions
The Orbits and Dynamical Masses of the Castor System
Castor is a system of six stars in which the two brighter objects, Castor A
and B, revolve around each other every 450 yr and are both short-period
spectroscopic binaries. They are attended by the more distant Castor C, which
is also a binary. Here we report interferometric observations with the CHARA
array that spatially resolve the companions in Castor A and B for the first
time. We complement these observations with new radial velocity measurements of
A and B spanning 30 yr, with the Hipparcos intermediate data, and with existing
astrometric observations of the visual AB pair obtained over the past three
centuries. We perform a joint orbital solution to solve simultaneously for the
three-dimensional orbits of Castor A and B as well as the AB orbit. We find
that they are far from being coplanar: the orbit of A is nearly at right angles
(92 degrees) relative to the wide orbit, and that of B is inclined about 59
degrees compared to AB. We determine the dynamical masses of the four stars in
Castor A and B to a precision better than 1%. We also determine the radii of
the primary stars of both subsystems from their angular diameters measured with
CHARA, and use them together with stellar evolution models to infer an age for
the system of 290 Myr. The new knowledge of the orbits enables us to measure
the slow motion of Castor C as well, which may assist future studies of the
dynamical evolution of this remarkable sextuple system.Comment: 17 pages in emulateapj format, including figures and tables. Accepted
for publication in The Astrophysical Journa
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