Living-learning communities improve first-year engineering student academic performance and retention at a small private university

Living-Learning Communities (LLCs), in which students share a residence, one or more classes, and extracurricular activities, have been shown to improve first-year student engagement, academic performance, and retention in non-engineering fields. Research on Engineering LLCs has focused primarily on student engagement. Two studies to examine performance and retention found that LLCs had little effect on first-semester grades but increased first-year retention in engineering by 2 to 12%. Unfortunately, one of these studies did not control for differences in incoming student characteristics, and another used a comparison group that differed little from the LLC group, possibly causing them to understate the LLC’s true effects. To improve our understanding, this paper examines performance and retention in the inaugural Engineering LLCs at a small, private non-profit, regional university in the northeastern United States. Results indicate that 82% of the Engineering LLC participants were retained within the engineering program, compared to 66% of first-year engineering students who chose not to participate. More strikingly, the average first-semester GPA of the LLC participants was 0.31 points (nearly a third of a letter grade) higher than that of the non-participants. To address the possibility that these improvements were caused by differences in incoming student characteristics, linear and logistic regression analyses were performed to control for gender, race/ethnicity, SAT scores, and other factors. These analyses suggest that LLC participation increased GPA by 0.35 points compared to first-year engineering students from prior years, while non-participation lowered GPA by 0.07 points. LLC participation increased the odds of retention in the major by 2.3 times compared to first-year students from prior years, while nonparticipation lowered the odds of retention by 1.35 times

Horizontal Product Differentiation in Auctions and Multilateral Negotiations

We experimentally compare first-price auctions and multilateral negotiations after introducing horizontal product differentiation into a standard procurement setting. The two institutions yield the buyer the same surplus, a difference from prior findings with homogeneous products that results from differentiation’s influence on the sellers’ pricing behavior. In particular, we find that introducing product differentiation intensifies price competition among the sellers in some treatments, and has no effect in others, which contrasts with the conventional wisdom that product differentiation softens competition.

High Resolution Near-Infrared Spectra of Protostars

We present new high resolution (R = 21,000) near-infrared (2 microns) spectroscopic observations of a sample of Class I and flat-spectrum protostellar objects in the rho Ophiuchi dark cloud. None of the five Class I spectra show CO v = 0 -- 2 absorption features, consistent with high K-band continuum veilings, 4 <= r_k <= 20 and fast stellar rotation, assuming that the underlying protostellar photospheres are of late spectral type, as is suggested by the low luminosities of most of these objects. Two of the flat-spectrum protostellar objects also show no absorption features and are likely to be highly veiled. The remaining two flat-spectrum sources show weak, broad absorptions which are consistent with an origin in quickly rotating (v sin i ~ 50 km / s) late-type stellar photospheres which are also strongly veiled, r_k = 3 - 4. These observations provide further evidence that: 1)-Class I sources are highly veiled at near-infrared wavelengths, confirming previous findings of lower resolution spectroscopic studies; and 2)- flat-spectrum protostars rotate more rapidly than classical T Tauri stars (Class II sources), supporting findings from a recent high resolution spectroscopic study of other flat-spectrum sources in this cloud. In addition our observations are consistent with the high rotation rates derived for two of the Class I protostellar objects in our sample from observations of variable hard X-ray emission obtained with the ASCA satellite. These observations suggest that certain Class I sources can rotate even more rapidly than flat-spectrum protostars, near breakup velocity.Comment: 16 pages including 2 tables and 2 figures (AASTeX 5.x) to be published in The Astronomical Journal July 200

Bilateral Protection and Other Determinants of Trade: A Gravity Model Approach

Replaced with revised version of paper 10/03/07.International Relations/Trade,

A Comparison of Auctions and Multilateral Negotiations

We compare first-price auctions to an exchange process that we term \u27multilateral negotiations.\u27 In multilateral negotiations, a buyer solicits price offers for a homogeneous product from sellers with privately known costs, and then plays the sellers off one another to obtain additional price concessions. Using the experimental method, we find that with four sellers, transaction prices are statistically indistinguishable in the two institutions, but with two sellers, prices are higher in multilateral negotiations than in first-price auctions. The institutions are equally efficient with two sellers, but multilateral negotiations are slightly more efficient with four sellers

Horizontal Product Differentiation in Auctions and Multilateral Negotiations

We experimentally compare first-price auctions and multilateral negotiations after introducing horizontal product differentiation into a standard procurement setting. Both institutions yield identical surplus for the buyer, a difference from prior findings with homogeneous products that results from differentiation\u27s influence on sellers\u27 pricing behaviour. The data are consistent with this finding being driven by concessions from low-cost sellers in response to differentiation reducing their likelihood of being the buyer\u27s surplus-maximizing trading partner. Further analysis shows that introducing product differentiation increases the intensity of price competition among sellers, which contrasts with the conventional wisdom that product differentiation softens competition

PROTEUS two-dimensional Navier-Stokes computer code, version 1.0. Volume 2: User's guide

A new computer code was developed to solve the two-dimensional or axisymmetric, Reynolds averaged, unsteady compressible Navier-Stokes equations in strong conservation law form. The thin-layer or Euler equations may also be solved. Turbulence is modeled using an algebraic eddy viscosity model. The objective was to develop a code for aerospace applications that is easy to use and easy to modify. Code readability, modularity, and documentation were emphasized. The equations are written in nonorthogonal body-fitted coordinates, and solved by marching in time using a fully-coupled alternating direction-implicit procedure with generalized first- or second-order time differencing. All terms are linearized using second-order Taylor series. The boundary conditions are treated implicitly, and may be steady, unsteady, or spatially periodic. Simple Cartesian or polar grids may be generated internally by the program. More complex geometries require an externally generated computational coordinate system. The documentation is divided into three volumes. Volume 2 is the User's Guide, and describes the program's general features, the input and output, the procedure for setting up initial conditions, the computer resource requirements, the diagnostic messages that may be generated, the job control language used to run the program, and several test cases