3,928 research outputs found
Can Everyone Make the Grade? Some Thoughts on Student Grading and Contemporary Classrooms
High school officials should consider alternative perspectives on grading in light of increasing student heterogeneity. Their challenge is to consider grading policies and practices that apply equally to students with and without diverse needs or disabilities. Schools should think about incorporating various combinations of percent, criterion-referenced, and norm-referenced grading into a more flexible policy on grading; ensure that student expectations are unambiguously described in writing and in sufficient detail; and subject their policies on grading to periodic review and be prepared to make any necessary modifications. Moreover, schools should collaborate with various stakeholders to develop policies on grading that guarantee objectivity and accountability for a diverse student population. Grading options that accurately and fairly reflect individual student performance are proposed
The Importance of Velocity Acceleration to Flow-Mediated Dilation
The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone
The Importance of Velocity Acceleration to Flow-Mediated Dilation
The validity of the flow-mediated dilation test has been questioned due to the lack of normalization to the primary stimulus, shear stress. Shear stress can be calculated using Poiseuille's law. However, little attention has been given to the most appropriate blood velocity parameter(s) for calculating shear stress. The pulsatile nature of blood flow exposes the endothelial cells to two distinct shear stimuli during the cardiac cycle: a large rate of change in shear at the onset of flow (velocity acceleration), followed by a steady component. The parameter typically entered into the Poiseuille's law equation to determine shear stress is time-averaged blood velocity, with no regard for flow pulsatility. This paper will discuss (1) the limitations of using Posieuille's law to estimate shear stress and (2) the importance of the velocity profile—with emphasis on velocity acceleration—to endothelial function and vascular tone
A Secondary Student Instructional Support Team (ASSIST): Teachers Face the Challenge of Student Diversity
The writers discuss the challenges related to instructing a diverse secondary-level student population. Many elementary and middle school teachers are benefiting from working collaboratively toward common instructional goals. Through collaboration, general and special education teachers can better address the content area needs of the individual students, foster a greater sense of shared responsibility for educating a heterogeneous population of students, increase communication across professional disciplines, enlarge the knowledge base and teaching repertoire of participants, and establish rewarding and long-lasting professional relationships. The concept of A Secondary Student Instructional Support Team (ASSIST) provides a realistic means for implementing the “class within a class” model that can better serve a heterogeneous student population. ASSIST is generally made up of teachers of various subject areas as well as one or more specialists. Placement of special needs students happens within and across team-taught classes. This is consistent with block scheduling options and facilitates the establishment of a positive attachment to team-mediated instruction. In addition, ASSIST can give students a mix of direct and indirect instructional support
Classification of protein interaction sentences via gaussian processes
The increase in the availability of protein interaction studies in textual format coupled with the demand for easier access to the key results has lead to a need for text mining solutions. In the text processing pipeline, classification is a key step for extraction of small sections of relevant text. Consequently, for the task of locating protein-protein interaction sentences, we examine the use of a classifier which has rarely been applied to text, the Gaussian processes (GPs). GPs are a non-parametric probabilistic analogue to the more popular support vector machines (SVMs). We find that GPs outperform the SVM and na\"ive Bayes classifiers on binary sentence data, whilst showing equivalent performance on abstract and multiclass sentence corpora. In addition, the lack of the margin parameter, which requires costly tuning, along with the principled multiclass extensions enabled by the probabilistic framework make GPs an appealing alternative worth of further adoption
Combination Rules, Charge Symmetry, and Hall Effect in Cuprates
The rule relating the observed Hall coefficient to the spin and charge
responses of the uniform doped Mott insulator is derived. It is essential to
include the contribution of holon and spinon three-current correlations to the
effective action of the gauge field. In the vicinity of the Mott insulating
point the Hall coefficient is holon dominated and weakly temperature dependent.
In the vicinity of a point of charge conjugation symmetry the holon
contribution to the observed Hall coefficient is small: the Hall coefficient
follows the temperature dependence of the diamagnetic susceptibility with a
sign determined by the Fermi surface shape. NOTE: document prepared using
REVTEX. (3 Figs, not included, available on request from: [email protected])Comment: 8 page
Expression and Site-Directed Mutagenesis of Type III Polyketide Synthases
Natural products are a well-established source of drugs, and evolution has yielded polyketides such as leinamycin and iso-migrastatin that have demonstrated anti-tumor activity. Polyketides are large metabolites with a high degree of chemical variability and are commonly produced by soil bacteria. Polyketide synthases (PKS) exist as three different archetypes, and the reaction mechanisms of ketosynthases from all archetypes is not understood. Type III PKSs exist as an independently functioning ketosynthase (KS), which primarily use coenzyme A (CoA), with some exceptions, for the biosynthesis of polyketides. We elected to focus our studies on ketosynthases, because they are responsible for forming the carbon-carbon bonds seen in polyketides. To study these Type III PKS KS, we expressed Streptomyces coelicolor germicidin synthase (Gcs) and tetrahydroxynaphthlene synthase (THNS) in E. coli and mutant versions where the catalytic active cysteine was changed to a serine or glutamine. In previous studies, serine slowed the overall progress of the reaction, and glutamine abolished carbon-carbon bond formation but promoted malonyl-CoA decarboxylation. We verified our mutations using a third party organization’s fluorescent sequencing by dye termination services, as well as confirmed that an acceptable level of expression of our protein is occurring in our BL21 cell lines using SDS-PAGE and Fast Protein Liquid Chromatography (FPLC). Now that we have successfully expressed and mutated our protein, we can move forward and use substrate mimics in conjunction with our mutants to further understand the catalytic mechanism of ketosynthases
Torsional fluctuations in columnar DNA assemblies
In columnar assemblies of helical bio-molecules the azimuthal degrees of
freedom, i.e. rotations about the long axes of molecules, may be important in
determining the structure of the assemblies especially when the interaction
energy between neighbouring molecules explicitly depends on their relative
azimuthal orientations. For DNA this leads to a rich variety of mesophases for
columnar assemblies, each categorized by a specific azimuthal ordering. In a
preceding paper [A. Wynveen, D. J. Lee, and A. A. Kornyshev, Eur. Phys. J. E,
16, 303 (2005)] a statistical mechanical theory was developed for the
assemblies of torsionally rigid molecues in order to determine how thermal
fluctuations influence the structure of these mesophases. Here we extend this
theory by including torsional fluctuations of the molecules, where a DNA
molecule may twist about its long axis at the cost of torsional elastic energy.
Comparing this with the previous study, we find that inclusion of torsional
fluctuations further increases the density at which the transition between the
hexagonal structure and the predicted rhombic phase occurs and reduces the
level of distortion in the rhombic phase. As X-ray diffraction may probe the
2-D lattice structure of such assemblies and provide information concerning the
underlying interaction between molecules, we have also calculated correlation
functions for the azimuthal ordering which are manifest in an x-ray scattering
intensity profiles.Comment: 33 pages, 8 figure
Mg(, )Na reaction study for spectroscopy of Na
The Mg(, )Na reaction was measured at the Holifield
Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to
better constrain spins and parities of energy levels in Na for the
astrophysically important F()Ne reaction rate
calculation. 31 MeV proton beams from the 25-MV tandem accelerator and enriched
Mg solid targets were used. Recoiling He particles from the
Mg(, )Na reaction were detected by a highly segmented
silicon detector array which measured the yields of He particles over a
range of angles simultaneously. A new level at 6661 5 keV was observed in
the present work. The extracted angular distributions for the first four levels
of Na and Distorted Wave Born Approximation (DWBA) calculations were
compared to verify and extract angular momentum transfer.Comment: 11 pages, 6 figures, proceedings of the 18th International Conference
on Accelerators and Beam Utilization (ICABU2014
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