When is an error not a prediction error? An electrophysiological investigation

A recent theory holds that the anterior cingulate cortex (ACC) uses reinforcement learning signals conveyed by the midbrain dopamine system to facilitate flexible action selection. According to this position, the impact of reward prediction error signals on ACC modulates the amplitude of a component of the event-related brain potential called the error-related negativity (ERN). The theory predicts that ERN amplitude is monotonically related to the expectedness of the event: It is larger for unexpected outcomes than for expected outcomes. However, a recent failure to confirm this prediction has called the theory into question. In the present article, we investigated this discrepancy in three trial-and-error learning experiments. All three experiments provided support for the theory, but the effect sizes were largest when an optimal response strategy could actually be learned. This observation suggests that ACC utilizes dopamine reward prediction error signals for adaptive decision making when the optimal behavior is, in fact, learnable

CONSTITUTION OF THE STATE OF GEORGIA A Resolution: Amend the Constitution so as to Provide that the Tradition of Fishing and Hunting and the Taking of Fish and Wildlife Shall be Preserved for the People and Shall be Managed by Law and Regulation for the Public Good; Provide for Submission of this Amendment for Ratification or Rejection; and for Other Purposes

The resolution sanctioned a state-wide referendum to amend the Georgia Constitution. The referendum will appear on the general election ballot in November 2006. Although Georgia Code section 27-1-3 recognizes the right to hunt and fish and the importance of the tradition of hunting and fishing to the State of Georgia, proponents contend that the resolution is a necessary step given the potential future threat. The proposed amendment preserves the tradition of hunting and fishing for the people of Georgia and provides management by law and regulation for the public good

The inter-outburst behavior of cataclysmic variables

Existing International Ultraviolet Explorer (IUE) and American Association of Variable Star Observers (AAVSO) archive data was used to accomplish a large scale study of what happens to the ultraviolet flux of accretion disk systems during the quiescent intervals between outbursts and how it relates to the preceding outburst characteristics of amplitude and width. The data sample involved multiple IUE observations for 16 dwarf novae and 8 novae along with existing optical coverage. Results indicate that most systems show correlated ultraviolet (UV) flux behavior with interoutburst phase, with 60 percent of the dwarf novae and 50 percent of the novae having decreasing flux trends while 33 percent of the dwarf novae and 38 percent of the novae show rising UV flux during the quiescent interval. All of the dwarf novae with decreasing UV fluxes at 1475A have orbital periods longer than 4.4 hours, while all (except BV Cen) with flat or rising fluxes at 1475A have orbital periods less than two hours. There are not widespread correlations of the UV fluxes with the amplitude of the preceding outburst and no correlations with the width of the outburst. From a small sample (7) that have relatively large quiescent V magnitude changes between the IUE observations, most show a strong correlation between the UV and optical continuum. Interpretation of the results is complicated by not being able to determine how much the white dwarf contributes to the ultraviolet flux. However, it is now evident that noticeable changes are occurring in the hot zones in accreting systems long after the outburst, and not only for systems that are dominated by the white dwarf. Whether these differences are due to different outburst mechanisms or to changes on white dwarfs which provide varying contributions to the UV flux remains to be determined

CONSTITUTION OF THE STATE OF GEORGIA A Resolution: Amend the Constitution so as to Provide that the Tradition of Fishing and Hunting and the Taking of Fish and Wildlife Shall be Preserved for the People and Shall be Managed by Law and Regulation for the Public Good; Provide for Submission of this Amendment for Ratification or Rejection; and for Other Purposes

The resolution sanctioned a state-wide referendum to amend the Georgia Constitution. The referendum will appear on the general election ballot in November 2006. Although Georgia Code section 27-1-3 recognizes the right to hunt and fish and the importance of the tradition of hunting and fishing to the State of Georgia, proponents contend that the resolution is a necessary step given the potential future threat. The proposed amendment preserves the tradition of hunting and fishing for the people of Georgia and provides management by law and regulation for the public good

Influence of Crop Rotation, Tillage, and Management Inputs on Weed Seed Production

Approaches to crop production that successfully reduce weed seed production can benefit farming systems by reducing management inputs and costs. A 5-yr rotation study was conducted in order to determine the effects that interactions between crop rotation, tillage, and amount of herbicide and fertilizer (management inputs) have on annual grass and broad-leaved weed seed production and fecundity. There were 10 crop rotation and tillage system combinations and three levels of management inputs (high, medium, and low). Green and yellow foxtail were the major weed species, and together they yielded between 76 and 93% of collected weed seeds. From 1990 to 1994, average grass weed seed productions were 7.3 by 103, 3.7 by 103 6.1 by 103 and 5.7 by 103 seeds m−-2, whereas average broad-leaved weed seed productions were 0.4 by 103, 0.4 by 103, 1.4 by 103, and 0.4 by 103 seeds m−-2 in crop rotations using conventional tillage (moldboard plow), conservation tillage, no tillage, and ridge tillage, respectively. Crop rotations using conventional or ridge tillage consistently produced more grass and broad-leaved weed seeds, especially in low-input plots. There was little difference in weed seed production among input levels for crop rotations using conservation tillage. Comparing rotations that began and ended with a corn crop revealed that by increasing crop diversity within a rotation while simultaneously reducing the amount of tillage, significantly fewer grass and broad-leaved weed seeds were produced. Among the rotations, grass and broad-leaved weed fecundity were highly variable, but fecundity declined from 1990 to 1994 within each rotation, with a concomitant increase in grass and broad-leaved weed density over the same period. Crop rotation in combination with reduced tillage is an effective way of limiting grass and broad-leaved weed seed production, regardless of the level of management input applied

Characterization of Soybean Yield Variability Using Crop Growth Models and 13C Discrimination

During the past several years, crop models have successfully been used to test the hypothesis that water stress is the primary factor that causes spatial yield variability in soybean [Glycine max (L.) Merr.] fields. However, there have been few attempts to validate this hypothesis through direct temporal and spatial measurements of water stress during the season. Recently, a technique has been developed to relate plant tissue 13C levels to the temporal water stress experienced by soybean plants. The purpose of this work was to compare the spatial yield loss simulated by a crop model with yield loss measured by 13C discrimination (∆) for a soybean field in South Dakota. The field was divided into 0.9-ha grids and the CROPGRO-Soybean model was calibrated to minimize error between simulated and observed yield in each grid over two seasons (1998, 2000). 13C discrimination was measured at 50 points representing 23 of the grids used in the crop modeling analysis in 2000. Simulated yield loss in grids that encompassed each 13C point in 2000 were compared to measurements of yield loss using the 13C discrimination technique. Initially, the root mean square error and r2 between simulated and measured yield loss was 259 kg ha-1 and 0.24, respectively. Upon closer inspection, it was observed that yield in 5 grids with the highest error likely were influenced by processes that are not represented in the crop model. Removing these values dramatically improved the agreement between simulated and observed yield loss, giving an RMSE of 216 kg ha-1 and r2 of 0.81. Both 13C discrimination and simulation results indicated that substantial yield loss occurred due to water stress in the summit/backslope areas of the field

Statistical Methods for Assessing Individual Oocyte Viability Through Gene Expression Profiles

In vivo derived oocytes are held as the gold standard for viability, other known origination methods are sub-par by comparison. Due to the low-viability of oocytes originating from these alternate methods, research was conducted to determine and quantify the validity of these alternate origination methods. However, the larger question of viability is on the individual oocyte level. We propose and compare methods of measurement based on gene expression profiles (GEPs) in order to assess oocyte viability, independent of oocyte origin. The first is based on a previously published wRMSD quantification of GEP differences. We also consider three novel methods: a distance comparison method, a tolerance interval method, and a classification-tree decision method; each utilizes a variable selection technique that focuses on the most differentially expressed genes. In our project, we obtain GEPs of individual swine oocytes and a general GEP distribution for in vivo oocytes. This distribution was the comparison standard for all oocytes, to gain a classification of viability. Each method is a valid method for driving viability decisions of the individual oocytes