Is commodity price volatility persistent? Another look using improved, full-sample estimates

Crop Production/Industries, Risk and Uncertainty,

What Explains High Commodity Price Volatility? Estimating a Unified Model of Common and Commodity-Specific, High- and Low-Frequency Factors

We estimate a model of common and commodity-specific, high- and low-frequency factors, built on the spline-GARCH model of Engle and Rangel (2008) to explain the period of exceptionally high price volatility in commodity markets during 2006-2008. We find that decomposing realized volatility into high- and low-frequency components reveals the impact of slowly-evolving macroeconomic variables on the price volatility. Further, we find that while macroeconomic variables have similar effects within the same commodity category (e.g., storable agricultural), they have different effects across commodity groups (e.g., live stock versus energy).volatility, spline-GARCH, futures markets, Agricultural Finance, Demand and Price Analysis,

A Prehispanic Maya Pit Oven? Microanalysis of Fired Clay Balls from the Puuc Region, Yucatán, Mexico

This is a postprint (author's final draft) version of an article published in Journal of Archaeological Science in 2013. The final version of this article may be found at http://dx.doi.org/10.1016/j.jas.2012.10.014 (login may be required). The version made available in OpenBU was supplied by the author.Excavations of a kitchen at Escalera al Cielo in the Puuc Maya region of Yucatán, Mexico uncovered a concentration of fired clay balls (ca. 3–5 cm in diameter), in addition to other de facto domestic refuse. The kitchen pertains to an intensively excavated elite residential group that was rapidly abandoned sometime near the end of the Terminal Classic period (A.D. 800–950), resulting in floor assemblages that provide an opportunity to explore the types and distribution of daily household activities. The results of experimental replications and a suite of analyses comprising modal analysis, ceramic petrography, Fourier transform infrared spectroscopy (FTIR), and microbotanical residue analysis reveal aspects of clay preparation, firing temperatures, repeated use of the balls, firing conditions, and specific plant food or fuel residues adhering to them. We show that the fired clay balls were manufactured with local, clay-rich soil and employed by the inhabitants of Escalera al Cielo as heating elements; relatively high concentrations of microbotanical residues from edible plants adhering to them support the hypothesis that they were involved in kitchen activities related to food processing

Engaging Young Fathers in Research through Photo-Interviewing

Although conducting interviews is the most popular research strategy in qualitative research, we question whether it is the best strategy to use with young fathers and other populations who may be less willing to share personal experiences and thoughts with an unknown researcher. The reluctance of young fathers to engage in research leads to the omission of important perspectives and inadvertently results in young fathers\u27 being understudied and unwittingly excluded from support programming and services. In this paper, we describe our experiences of using two different research strategies with young fathers: conventional in-depth interviews (i.e., interviews that rely on words only) and photo-interviewing (i.e., using photographs as props during an interview). We found that photo-interviewing contributed to young fathers\u27 comfort during the research process, provided them a sense of agency, and possibly enriched the quality of the data. While we do not argue that one data collection strategy is necessarily better than the other, we would like to caution researchers against using conventional interviews as a default data collection strategy with marginalized, vulnerable, or less verbal populations for whom interviewing may not be the most suitable data collection strategy and to encourage researchers to explore alternative options

Water: a neglected nutrient in the young child? A South African perspective

Water is considered an essential nutrient because the body cannot produce enough water itself, by metabolism of food, to fulfil its need.When the quantity or quality of water is inadequate, health problems result, most notably dehydration and diarrhoea. As a result of contaminated water and poor hygiene, related infections are still a serious problem. Indeed, in the South African setting water availability and sanitation are critical issues because of the prevalence of childhood diarrhoea and also the HIV/AIDS crisis.Though considerable efforts have been made to improve the water and sanitation problems in South Africa – especially with regard to water supply infrastructure – there is still room for much improvement.Water is a healthy alternative to calorie-dense, non-nutritive beverages, such as artificial fruit drinks and soda. The latter should be avoided as they contribute little other than energy and may contribute to overweight and obesity.Also, they displace more nutritious foods from the child’s diet. Consumption of fruit juice should also be limited. These issues highlight the need for a specific guideline relating to water intake in the paediatric food-based dietary guidelines

Extended skyrmion lattice scattering and long-time memory in the chiral magnet Fe1−x_{1-x}Cox_xSi

Small angle neutron scattering measurements on a bulk single crystal of the doped chiral magnet Fe$_{1-x}$Co$_x$Si with $x$=0.3 reveal a pronounced effect of the magnetic history and cooling rates on the magnetic phase diagram. The extracted phase diagrams are qualitatively different for zero and field cooling and reveal a metastable skyrmion lattice phase outside the A-phase for the latter case. These thermodynamically metastable skyrmion lattice correlations coexist with the conical phase and can be enhanced by increasing the cooling rate. They appear in a wide region of the phase diagram at temperatures below the $A$-phase but also at fields considerably smaller or higher than the fields required to stabilize the A-phase

VR BioViewer - A new interactive-visual model to represent medical information

Virtual reality (VR) techniques to understand and obtain conclusions of data in an easy way are being used by the scientific community. However, these techniques are not used frequently for analyzing large amounts of data in life sciences, particularly in genomics, due to the high complexity of data (curse of dimensionality). Nevertheless, new approaches that allow to bring out the real important data characteristics, arise the possibility of constructing VR spaces to visually understand the intrinsic nature of data. It is well known the benefits of representing high dimensional data in tridimensional spaces by means of dimensionality reduction and transformation techniques, complemented with a strong component of interaction methods. Thus, a novel framework, designed for helping to visualize and interact with data about diseases, is presented. In this paper, the framework is applied to the Van't Veer breast cancer dataset is used, while oncologists from La Paz Hospital (Madrid) are interacting with the obtained results. That is to say a first attempt to generate a visually tangible model of breast cancer disease in order to support the experience of oncologists is presented

Physical Activity and Hippocampal Sub-Region Structure in Older Adults with Memory Complaints.

BackgroundPhysical activity (PA) plays a major role in maintaining cognition in older adults. PA has been shown to be correlated with total hippocampal volume, a memory-critical region within the medial temporal lobe (MTL). However, research on associations between PA and MTL sub-region integrity is limited.ObjectiveTo examine the relationship between PA, MTL thickness, and its sub-regions, and cognitive function in non-demented older adults with memory complaints.MethodsTwenty-nine subjects aged ≥60 years, with memory complaints were recruited for this cross-sectional study. PA was tracked for 7 days using accelerometers, and average number of steps/day determined. Subjects were categorized into two groups: those who walked ≤4000 steps/day (lower PA) and those with >4000 steps/day (higher PA). Subjects received neuropsychological testing and 3T MRI scans. Nonparametric ANCOVAs controlling for age examined differences between the two groups.ResultsTwenty-six subjects aged 72.7(8.1) years completed the study. The higher PA group (n = 13) had thicker fusiform gyrus (median difference = 0.11 mm, effect size (ES) = 1.43, p = 0.001) and parahippocampal cortex (median difference = 0.12 mm, ES = 0.93, p = 0.04) compared to the lower PA group. The higher PA group also exhibited superior performance in attention and information-processing speed (median difference = 0.90, ES = 1.61, p = 0.003) and executive functioning (median difference = 0.97, ES = 1.24, p = 0.05). Memory recall was not significantly different between the two groups.ConclusionOlder non-demented individuals complaining of memory loss who walked >4000 steps each day had thicker MTL sub-regions and better cognitive functioning than those who walked ≤4000 steps. Future studies should include longitudinal analyses and explore mechanisms mediating hippocampal related atrophy

Medial Prefrontal Cortical Thinning Mediates Shifts in Other-Regarding Preferences during Adolescence

Adolescence is a time of significant cortical changes in the ‘social brain’, a set of brain regions involved in sophisticated social inference. However, there is limited evidence linking the structural changes in social brain to development of social behavior. The present study investigated how cortical development of the social brain relates to other-regarding behavior, in the context of fairness concerns. Participants aged between 9 to 23 years old responded to multiple rounds of ultimatum game proposals. The degree to which each participant considers fairness of intention (i.e., intention-based reciprocity) vs. outcome (i.e., egalitarianism) was quantified using economic utility models. We observed a gradual shift in other-regarding preferences from simple rule-based egalitarianism to complex intention-based reciprocity from early childhood to young adulthood. The preference shift was associated with cortical thinning of the dorsomedial prefrontal cortex and posterior temporal cortex. Meta-analytic reverse-inference analysis showed that these regions were involved in social inference. Importantly, the other-regarding preference shift was statistically mediated by cortical thinning in the dorsomedial prefrontal cortex. Together these findings suggest that development of the ability to perform sophisticated other-regarding social inference is associated with the structural changes of specific social brain regions in late adolescence