Validating automated essay scoring for online writing placement

In this paper, I describe the design and evaluation of automated essay scoring (AES) models for an institution's writing placement program. Information was gathered on admitted student writing performance at a science and technology research university in the northeastern United States. Under timed conditions, first-year students (N = 879) were assigned to write essays on two persuasive prompts within the Criterion^® Online Writing Evaluation Service at the beginning of the semester. AES models were built and evaluated for a total of four prompts. AES models meeting recommended performance criteria were then compared to standardized admissions measures and locally developed writing measures. Results suggest that there is evidence to support the use of Criterion as part of the placement process at the institution.     

Quantum states of neutron in Earth’s gravitional field: A challenge from the 36th international physics olympaid

This article describes a challenging problem concerning a neutron under gravity that was posed as a theoretical problem in the 36th International Physics Olympiad held in Salamanca, Spain from July 3–12, 2005. The Olympiad marked India’s eighth foray into this exciting event where seventyfive nations participated. Our performance was a success and all five student members of the team secured medals which included two gold, two silver and one bronze medals.     

Utilizing microfluidics to synthesize polyethylene glycol microbeads for Förster resonance energy transfer based glucose sensing

Here, we utilize microfluidic droplet technology to generate photopolymerizeable polyethylene glycol (PEG) hydrogel microbeads incorporating a fluorescence-based glucose bioassay. A microfluidic T-junction and multiphase flow of fluorescein isothiocyanate dextran, tetramethyl rhodamine isothiocyanate concanavalin A, and PEG in water were used to generate microdroplets in a continuous stream of hexadecane. The microdroplets were photopolymerized mid-stream with ultraviolet light exposure to form PEG microbeads and were collected at the outlet for further analysis. Devices were prototyped in PDMS and generated highly monodisperse 72?±?2 μm sized microbeads (measured after transfer into aqueous phase) at a continuous flow rate between 0.04 ml/h-0.06 ml/h. Scanning electron microscopy analysis was conducted to analyze and confirm microbead integrity and surface morphology. Glucose sensing was carried out using a F?rster resonance energy transfer (FRET) based assay. A proportional fluorescence intensity increase was measured within a 1-10 mM glucose concentration range. Microfluidically synthesized microbeads encapsulating sensing biomolecules offer a quick and low cost method to generate monodisperse biosensors for a variety of applications including cell cultures systems, tissue engineering, etc.     

Utilizing microfluidics to synthesize polyethylene glycol microbeads for F?rster resonance energy transfer based glucose sensing

Here, we utilize microfluidic droplet technology to generate photopolymerizeable polyethylene glycol (PEG) hydrogel microbeads incorporating a fluorescence-based glucose bioassay. A microfluidic T-junction and multiphase flow of fluorescein isothiocyanate dextran, tetramethyl rhodamine isothiocyanate concanavalin A, and PEG in water were used to generate microdroplets in a continuous stream of hexadecane. The microdroplets were photopolymerized mid-stream with ultraviolet light exposure to form PEG microbeads and were collected at the outlet for further analysis. Devices were prototyped in PDMS and generated highly monodisperse 72 ± 2 μm sized microbeads (measured after transfer into aqueous phase) at a continuous flow rate between 0.04 ml/h—0.06 ml/h. Scanning electron microscopy analysis was conducted to analyze and confirm microbead integrity and surface morphology. Glucose sensing was carried out using a Förster resonance energy transfer (FRET) based assay. A proportional fluorescence intensity increase was measured within a 1–10 mM glucose concentration range. Microfluidically synthesized microbeads encapsulating sensing biomolecules offer a quick and low cost method to generate monodisperse biosensors for a variety of applications including cell cultures systems, tissue engineering, etc.     

The real effects of pseudo forces

A clear comprehension of the Newtonian notion of force remains elusive to many students due to lack of experience with observations in a noninertial frame of reference. In this article is described a software that can be easily run on a desktop computer and which acquaints the student user with the Newtonian notion of force. Fundamental principles of causality and determinism in Newtonian mechanics are elucidated.     

The importance of number sense to mathematics achievement in first and third grades

Children's symbolic number sense was examined at the beginning of first grade with a short screen of competencies related to counting, number knowledge, and arithmetic operations. Conventional mathematics achievement was then assessed at the end of both first and third grades. Controlling for age and cognitive abilities (i.e., language, spatial, and memory), number sense made a unique and meaningful contribution to the variance in mathematics achievement at both first and third grades. Furthermore, the strength of the predictions did not weaken over time. Number sense was most strongly related to the ability to solve applied mathematics problems presented in various contexts. The number sense screen taps important intermediate skills that should be considered in the development of early mathematics assessments and interventions.     

Low cost demonstration experiment Lorentz force: Change in path of charged particles in magnetic field

The path of charged particles is affected when they enter a magnetic field. This change of path largely depends on the angle between the applied magnetic field and the direction of motion of the charged particle (and its velocity) entering the magnetic field. This is demonstrated by means of a simple, low-cost experiment. A high voltage is used to ionize the air between a spark gap. The flow of charged particles between the spark gap is altered by applying a magnetic field from a rare earth permanent magnet having surface magnetic field induction of 0.12 T.     

Predicting First‐Grade Math Achievement from Developmental Number Sense Trajectories

Number sense development was tracked from the beginning of kindergarten through the middle of first grade, over six time points. Children (n= 277) were then assessed on general math achievement at the end of first grade. Number sense performance in kindergarten, as well as number sense growth, accounted for 66 percent of the variance in first‐grade math achievement. Background characteristics of income status, gender, age, and reading ability did not add explanatory variance over and above growth in number sense. Even at the beginning of kindergarten, number sense was highly correlated with end of first‐grade math achievement (r= 0.70). Clarifying the observed slope effect, general growth mixture modeling showed that children who started kindergarten with low number sense but made moderate gains by the middle of kindergarten had higher first‐grade math achievement than children who started out with similarly low number sense with flat growth. The majority of children in the low/flat growth class were from low‐income families. The findings indicate that screening early number sense development is useful for identifying children who will face later math difficulties or disabilities.