Semiochemicals of the honeybee queen mandibular glands

The ontogeny of the five queen mandibular gland semiochemicals that initiate and maintain the retinue behavior of worker honeybees was investigated by quantitative splitless capillary gas chromatography. No detectable pheromone is present at the time of eclosion, but decenoic acid levels build up rapidly during the first week of the queen's life. Two aromatic components attain detectable levels later, with the more plentiful methylp-hydroxybenzoate preceding the 4-hydroxy-3-methoxyphenylethanol. Pheromone levels are maximal in mature, mated, laying queens. The ratio of (R,E)-(–)-9-hydroxy-2-decenoic acid to the (S,E)-(+) enantiomer increases with the age of the queen. Pheromone levels in queen mandibular glands are largely unaffected by queen banking, restraint with workers in mailing cages, and limited storage on dry ice. All major body parts of typical queens, especially the head and legs, have sufficient mandibular exudate to be highly attractive to worker bees.     

The mechanism of the corrosion inhibition of carbon steel in neutral medium by chromate and nickel ions

The electrochemical behaviour of carbon steel in 3.5% NaCl solutions containing dichromate and nickel ions, has been investigated by anodic polarization curves and gravimetric measurements. The presence of Cr/Ni ions, as low as 0.005 M, in the chloride medium has been observed in this study to inhibit the aggressiveness of the corrodent for the carbon steel by a noble shift of the corrosion potential, E_corr, of the metal. Interface and interphase inhibition mechanisms are proposed to suggest explanations for the inhibiting experimental observations of these ions in the corrosion of carbon steel.     

Infant preferences for attractive faces: Rudiments of a stereotype?

Two studies, one with 2- to 3-month-olds and one with 6- to 8-month-olds, were conducted to examine infant preferences for attractive faces. A standard visual preference technique was used in which infants were shown pairs of color slides of the faces of adult women previously rated by other adults for attractiveness. The results showed that both the older and younger infants looked longer at attractive faces when the faces were presented in contrasting pairs of attractiveness (attractive/unattractive). When the faces were presented in pairs of similar levels of attractiveness (attractive/attractive vs. unattractive/unattractive) the older but not the younger infants looked longer at attractive faces. The results challenge the commonly held assumption that standards of attractiveness are learned through gradual exposure to the current cultural standard of beauty and are merely "in the eye of the beholder." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formulation and Characterization of a New Nitroglycerin‐Free Double Base Propellant

Double base propellants composed of nitrocellulose (NC) and nitroglycerine (NG) are widely used. However, the inclusion of liquid NG presents both stability and performance problems: the NG may migrate from the propellant in storage, and it softens the propellant at high inclusion levels. In this work, the novel nitrate ester 1,4‐dinitrato‐2,3‐dinitro‐2,3bis(nitratomethylene) butane (SMX) is considered as a replacement for NG in a double base propellant. Thermochemical calculations indicate improved performance when compared with the common double base propellant JA2 at SMX loadings above 40 wt‐%. Also, since SMX is a room temperature solid, migration may be mitigated. Both unplasticized and plasticized propellants were formulated to enable the study of the interaction of SMX with nitrocellulose. Thermal analysis of unplasticized propellant showed a distinct melt‐recrystallization curve, which indicates that a solid phase solution is being formed between SMX and NC, and that SMX would not act as plasticizer. Analysis of propellant prepared with diethyleneglycol dinitrate (DEGDN) plasticizer indicates that the SMX is likely dissolved in the DEGDN. The plasticized material also showed similar hardness and modulus to JA2. Safety characterization showed that sensitivity is similar to JA2. In short, replacing NG with SMX results in a new family of propellants with acceptable safety characteristics and which may also offer improved theoretical performance.     

Exploring the impact of the 2008 global food crisis on food security among vulnerable households in rural South Africa

Recurring food crises endanger the livelihoods of millions of households in developing countries around the globe. Owing to the importance of this issue, we explored recent changes in food security between the years 2004 and 2010 in a rural district in Northeastern South Africa. Our study window spans the time of the 2008 global food crisis and allows the investigation of its impacts on rural South African populations. Grounded in the sustainable livelihood framework, we examined differences in food security trajectories among vulnerable sub populations. A unique panel data set of 8,147 households, provided by the Agincourt Health and Demographic Surveillance System (Agincourt HDSS), allowed us to employ a longitudinal multilevel modeling approach to estimate adjusted growth curves for the differential changes in food security across time. We observed an overall improvement in food security that leveled off after 2008, most likely resulting from the global food crisis. In addition, we discovered significant differences in food security trajectories for various sub populations. For example, female-headed households and those living in areas with better access to natural resources differentially improved their food security situation, compared to male-headed households and those households with lower levels of natural resource access. However, former Mozambican refugees witnessed a decline in food security. Therefore, poverty alleviation programs for the Agincourt region should work to improve the food security of vulnerable households, such as former Mozambican refugees.     

The persistence of attention-deficit/hyperactivity disorder into young adulthood as a function of reporting source and definition of disorder.

This study examined the persistence of attention-deficit/hyperactivity disorder (ADHD) into young adulthood using hyperactive (N=147) and community control (N=71) children evaluated at ages 19-25 years. ADHD was rare in both groups (5% vs. 0%) based on self-report but was substantially higher using parent reports (46% vs. 1.4%). Using a developmentally referenced criterion (+2 SD), prevalence remained low for self-reports (12% vs. 10%) but rose further for parent reports (66% vs. 8%). Parent reports were more strongly associated with major life activities than were self-reports. Recollections of childhood ADHD showed moderate correlations with actual parent ratings collected in childhood, which suggests some validity for such recollections. The authors conclude that previous follow-up studies that relied on self-reports might have substantially underestimated the persistence of ADHD into adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of drought on the physicochemical,nutrient, and carbon metrics of flows in the Savannah River,Georgia, USA

Hydrological drought has wide-ranging impacts on water quality, nutrient and carbon metrics, and given the uncertainty of climate change and the predicted increased frequency and intensity of drought in the future, investigations into changes induced by drought become increasingly important. This study compared physicochemical parameters (temperature, conductivity, pH and DO), nutrients (TN, NO_X [NO₂ + NO₃], NH₃ and TP) and carbon (TOC and DOC) between hydrological drought conditions (2006–2008) and hydrological normal conditions (2016–2019) at five sites along the lower Savannah River (Georgia, USA). Although we had predicted that water temperatures would increase from drought, we instead found temperature was significantly lower during drought conditions. Levels of pH and DO were significantly higher during drought. Further, TN, TOC and DOC concentrations were significantly lower during drought, but NO_X concentrations were significantly higher during drought. Conductivity varied at the lower river sites, being significantly higher during drought at sites located below the city of Augusta, GA. These complex changes could be attributed to volume reductions coupled with an increase in the percentage of total flow originating from groundwater as well as limnetic reservoir inputs, persistent point source pollution, reduced natural catchment inputs and/or reduced floodplain interactions. The changes that occurred during drought may be disruptive to aquatic life, not only from reduced water quantity but also due to a scarcity of some biologically essential materials and lower food resources, combined with artificially high levels of some other potentially stressful materials.