What Can we Learn from our Mistakes? Evaluating the Benefits of Correcting Inefficiencies in USDA Cotton Forecasts.

This study investigated the magnitude of forecast improvements resulting from correction of inefficiencies in USDA cotton forecasts over 1999/00 to 2008/09 marketing years. The aspects of forecast performance included in this study were 1) bias and trends in bias, 2) correlation between forecast error and forecast level, 3) autocorrelation in forecast errors, 4) correlation in forecast revisions. Overall the results of this study demonstrated that some corrections of forecast inefficiencies, such as correction of correlation of error with forecast levels and correlation of error with previous year’s error resulted in consistent improvement of USDA cotton forecasts, while correction for correlation in forecast revisions did not benefit the forecasts. Correction for bias yielded mixed results likely because USDA has already been applying those corrections to some of the categories and thus our analysis resulted in over-correcting. The framework developed in this study can be used by USDA and other agencies to monitor and improve the performance of their forecasts.Commodity, Forecast evaluation, Fixed-event forecasts, Government forecasting, Forecast improvement, Agribusiness, Demand and Price Analysis, E37, E3, Q13,

Orthogonality of Jack polynomials in superspace

Jack polynomials in superspace, orthogonal with respect to a ``combinatorial'' scalar product, are constructed. They are shown to coincide with the Jack polynomials in superspace, orthogonal with respect to an ``analytical'' scalar product, introduced in hep-th/0209074 as eigenfunctions of a supersymmetric quantum mechanical many-body problem. The results of this article rely on generalizing (to include an extra parameter) the theory of classical symmetric functions in superspace developed recently in math.CO/0509408Comment: 22 pages, this supersedes the second part of math.CO/0412306; (v2) 24 pages, title and abstract slightly modified, minor changes, typos correcte

Stem Cells to Insulin Secreting Cells: Two Steps Forward and Now a Time to Pause?

Two groups recently reported the in vitro differentiation of human embryonic stem cells into insulin-secreting cells, achieving an elusive goal for regenerative medicine. Herein we provide a perspective regarding these developments, compare phenotypes of the insulin-containing cells to human β cells, and discuss implications for type 1 diabetes research and clinical care

In vivo assessment of serotonergic signaling pathways underlying the corticolimbic response to threat in humans

A corticolimbic circuit including the amygdala and medial prefrontal cortex (mPFC) affects sensitivity to threat, related aspects of personality and risk for psychopathology. Serotonin (5‐HT) is a potent neuromodulator of this circuit, however, 5‐HT receptors mediating these effects and genetic sources of variability in 5‐HT receptor availability are not understood. We determined the association between 5‐HT1A and 5‐HT2A binding and the response to threat within this corticolimbic circuit using a multimodal neuroimaging strategy in humans in vivo. Corticolimbic circuit function was assessed with a threat‐related faces matching paradigm using functional magnetic resonance imaging (fMRI). Regional 5‐HT1A and 5‐HT2A binding was assessed with [11C]WAY100635 and [18F]altanserin PET, respectively. We evaluated the association between receptor binding and common polymorphisms (rs6295, rs6311 and 5‐HTTLPR) in 5‐HT related genes.In Study 1 we found that 5‐HT1A binding within the dorsal raphe nucleus was inversely associated with threat‐related amygdala reactivity. This is consistent with 5‐HT1A autoreceptors negatively regulating 5‐HT release, which within the amygdalapotentiates its response to threat. In Study 2 we found that mPFC 5‐HT2A binding was inversely associated with threat‐related amygdala reactivity and positively associated with amygdala habituation and amygdala‐mPFC functional connectivity. In Study 3 we found that mPFC 5‐HT1A binding significantly moderated the inverse association between mPFC 5‐HT2A binding and amygdala reactivity.These findings are consistent with the co‐localization of 5‐HT1A and 5‐HT2A on glutamatergic neurons within mPFC indicating the 5‐HT2A receptor is localized to facilitate regulation of the amygdala and the 5‐HT1A receptor is localized to moderate its effects within mPFC. In Study 4 we found that 5‐HTTLPR genotype predicted 5‐HT1A and 5‐HT2A binding in brain regions within this circuit such that the S and LG alleles were associated with reduced 5‐HT1A and 5‐HT2A binding.These findings provide novel insight into mechanisms that mediate the effects of 5‐HT signaling on the response to threat of a key corticolimbic circuit in humans. Our findings indicate that 5‐HT1A and 5‐HT2A receptors contribute significantly to threat‐related corticolimbic circuit function in humans. Furthermore, the 5‐HTTLPR may contribute to individual variability in neural and behavioral sensitivity to threat by biasing 5‐HT1A and 5‐HT2A availability

Microsystems manufacturing technologies for pharmaceutical toxicity testing

To meet the demands of political, ethical and scientific pressures on animal testing, research into possible alternatives is required. Data obtained with animal models often cannot be related to humans. Testing with current cell-based assays, microdosing and pharmacokinetic models contribute to reducing animal testing and improving the drug development process. Micro-fabrication and rapid prototyping techniques offer potential solutions to reduce the need for animal toxicity testing. The aim of this research was to develop biological platforms for in vitro toxicity testing to provide physiologically relevant, high-throughput solutions to reduce animal testing. This was achieved by investigating and integrating microfabrication methods of microfluidics, dielectrophoresis and additive manufacturing. Three approaches were taken: (i) micro-pattern protein arrays for primary hepatocyte cell culture enclosed within microfluidics devices for high-throughput toxicity testing. It was observed that hepatocytes attached to the micro-pattern within microfluidics and maintained viability, however liver specific functions observed by florescence assays, the P450 enzymes, were observed to be reduced compared to Petri dish conditions. (ii) A biomimetic dielectrophoretic cell patterning technique to form liver lobule-like tissue structures within agar on a paper substrate was developed for toxicity testing. Observation of these biomimetic micro liver structures showed high viability (80-90%) and an increase in liver specific function marker albumin protein (20%) compared to control samples after 48 hours. (iii) Rapid prototyping methods were explored with regard to fabrication of microfluidic chips for the automated trapping, imaging and analysis of zebrafish embryos. Monolithic microfluidic chips for zebrafish were developed to be suitable for optical based toxicity assays. The biocompatibility of 3D printed materials was investigated. A method to render the photopolymer Dreve Fototec 7150 compatible with zebrafish culture was observed to provide 100% viability. Future development of this research will aim to (i) develop the liver lobule-like system to use layers of multiple cell types to form complex micro-liver models using additive manufactured microfluidic systems for toxicity testing. (ii) Automation of zebrafish handing using additive manufactured microfluidic devices for in-situ analysis of dechorionated zebrafish for high-throughput toxicity studies