Putting Behavioral Economics to Work: Testing for Gift Exchange in Labor Markets Using Field Experiments

Recent discoveries in behavioral economics have led scholars to question the underpinnings of neoclassical economics. We use insights gained from one of the most influential lines of behavioral research -- gift exchange -- in an attempt to maximize worker effort in two quite distinct tasks: data entry for a university library and door-to-door fundraising for a research center. In support of the received literature, our field evidence suggests that worker effort in the first few hours on the job is considerably higher in the "gift" treatment than in the "non-gift treatment." After the initial few hours, however, no difference in outcomes is observed, and overall the gift treatment yielded inferior aggregate outcomes for the employer: with the same budget we would have logged more data for our library and raised more money for our research center by using the market-clearing wage rather than by trying to induce greater effort with a gift of higher wages.

The polymer mat: Arrested rebound of a compressed polymer layer

Compression of an adsorbed polymer layer distorts its relaxed structure. Surface force measurements from different laboratories show that the return to this relaxed structure after the compression is released can be slowed to the scale of tens of minutes and that the recovery time grows rapidly with molecular weight. We argue that the arrested state of the free layer before relaxation can be described as a Guiselin brush structure1, in which the surface excess lies at heights of the order of the layer thickness, unlike an adsorbed layer. This brush structure predicts an exponential falloff of the force at large distance with a decay length that varies as the initial compression distance to the 6/5 power. This exponential falloff is consistent with surface force measurements. We propose a relaxation mechanism that accounts for the increase in relaxation time with chain length.Comment: 24 pages, 5 figre

Timing matters: impact of anticonvulsant drug treatment and spikes on seizure risk in benign epilepsy with centrotemporal spikes

OBJECTIVE: Benign epilepsy with centrotemporal spikes (BECTS) is a common, self-limited epilepsy syndrome affecting school-age children. Classic interictal epileptiform discharges (IEDs) confirm diagnosis, and BECTS is presumed to be pharmacoresponsive. As seizure risk decreases in time with this disease, we hypothesize that the impact of IEDs and anticonvulsive drug (ACD) treatment on the risk of subsequent seizure will differ based on disease duration. METHODS: We calculate subsequent seizure risk following diagnosis in a large retrospective cohort of children with BECTS (n = 130), evaluating the impact of IEDs and ACD treatment in the first, second, third, and fourth years of disease. We use a Kaplan-Meier survival analysis and logistic regression models. Patients were censored if they were lost to follow-up or if they changed group status. RESULTS: Two-thirds of children had a subsequent seizure within 2 years of diagnosis. The majority of children had a subsequent seizure within 3 years despite treatment. The presence of IEDs on electroencephalography (EEG) did not impact subsequent seizure risk early in the disease. By the fourth year of disease, all children without IEDs remained seizure free, whereas one-third of children with IEDs at this stage had a subsequent seizure. Conversely, ACD treatment corresponded with lower risk of seizure early in the disease but did not impact seizure risk in later years. SIGNIFICANCE: In this cohort, the majority of children with BECTS had a subsequent seizure despite treatment. In addition, ACD treatment and IEDs predicted seizure risk at specific points of disease duration. Future prospective studies are needed to validate these exploratory findings.Published versio

Compaction dynamics in ductile granular media

Ductile compaction is common in many natural systems, but the temporal evolution of such systems is rarely studied. We observe surprising oscillations in the weight measured at the bottom of a self-compacting ensemble of ductile grains. The oscillations develop during the first ten hours of the experiment, and usually persist through the length of an experiment (one week). The weight oscillations are connected to the grain--wall contacts, and are directly correlated with the observed strain evolution and the dynamics of grain--wall contacts during the compaction. Here, we present the experimental results and characteristic time constants of the system, and discuss possible reasons for the measured weight oscillations.Comment: 11 pages, 14 figure

Detecting Low-Velocity Impact Damage in Composite Plates via a Minimization of Measured and Simulated Origin Approach

In this paper, a new method for identifying impact locations applying a comparative simulated approach of minimization of measurement error against simulated data in a composite carbon plate-like structure using acoustic Lamb wave is proposed and reviewed. The purposed model detects impact locations by using an error minimizing algorithm based on the measured Lamb waves from an actual real impact and demonstrates a high-level of flexibility. Furthermore, the proposed model can be straightforwardly calibrated for different velocities and other parameters inherent in carbon-based structures, reducing the effects of the structure’s anisotropic properties. In particular, the time of arrival of an impact signal is calculated by applying wavelet transform and threshold crossing methods. Experiment results illustrate the effectiveness of the proposed method by presenting a very accurate detection rate of real low-velocity impacts on a carbon-based plate-like structure. This promising technique enables inspection and on-line monitoring of impacts on composite structures. Further developments of the suggested model are discussed, and are mainly focused on producing a velocity independent extension mode

Welcome Night

The GLBT Center had it\u27s Welcome Night in Adams Hall in September of 2011. A special thanks for the GLBT Center staff. Niki HartmanSamantha BarrusJustin WillnerDana SpeeslerKevin CruzRiley DavisBrian SitJoseph Santiag