Effects of chronic estradiol treatment on delayed spatial alternation and differential reinforcement of low rates of responding.

Estrogens have been shown to both enhance and impair cognitive function depending on several factors, including regimen of hormone treatment, age of subject, and task attributes. In rodent models, estradiol tends to enhance spatial learning and impair response or cued learning, but effects on executive functions are less well-studied. In this experiment, spatial working memory and response inhibition were tested using delayed spatial alternation (DSA) and differential reinforcement of low rates of responding (DRL) tasks in ovariectomized rats that were given chronic estradiol via Silastic implants resulting in serum estradiol concentrations of 86.2 ± 8.2 (SEM) pg/ml. Rats were tested for 25 days DSA with variable delays of 0, 3, 6, 9, and 18 seconds between lever presentations, followed by 30 days on a DRL-15s operant schedule. Estradiol-replaced rats showed a significantly lower proportion of correct responses on the DSA task compared to vehicle-implanted ovariectomized animals. On DRL, estradiol-treated rats showed a lower ratio of reinforced to nonreinforced presses. These data suggest that chronic estrogen exposure may impair rats' abilities on measures of executive function including working memory and response inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related differences in cognition: The role of distraction control.

The ability to ignore or control the processing of distracting information may underlie many age-related and individual differences in cognitive abilities. Using a large sample of adults aged 18 to 87 years, this article presents data examining the mediating role of distraction control in the relationship between age and higher order cognition. The reading with distraction task (Connelly, Hasher, & Zacks, 1991) has been used as a measure of the access function of distraction control. Results of this study suggest that distraction control, as measured by this paradigm, plays an important role in mediating age-related effects on measures of working memory and matrix reasoning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Let your preference be your guide? Preferences and choices are more tightly linked for North Americans than for Indians.

Using experimental paradigms from economics and social psychology, the authors examined the cross-cultural applicability of 3 widely held assumptions about preference and choice: People (a) recruit or construct preferences to make choices; (b) choose according to their preferences; and (c) are motivated to express their preferences in their choices. In 6 studies, they compared how middle-class North American and Indian participants choose among consumer products. Participants in both contexts construct nonrandom preferences at similar speeds. Those in Indian contexts, however, are slower to make choices, less likely to choose according to their personal preferences, and less motivated to express their preferences in their choices. The authors infer that the strong link between preferences and choices observed among North Americans is not a universal feature of human nature. Instead, this link reflects the disjoint model of agency, which prescribes that people should choose freely on the basis of their preferences. In contrast, Indian contexts reflect and promote a conjoint model of agency, according to which agency is responsive to the desires and expectations of important others and may require restraining one's preferences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modelling regional lottery sales: Methodological issues and a case study from Spain

Sales are modelled for 50 Spanish provinces over 522 draws of a high prize lotto game. A crossed random effects model allows for random shocks specific to particular draws and to particular provinces. The paper explores how demographic and socio‐economic factors influence sales volumes, with particular focus on the relationship between sales and real per capita income at different jackpot sizes. When jackpots are low, sales are shown to rise with the level of provincial incomes. But this relationship disappears or is reversed when rollovers raise the jackpot because sales in poorer provinces are markedly more responsive to jackpot size.     

Passivation of Molecular n‐Doping: Exploring the Limits of Air Stability

Molecular doping is a key technique for flexible and low‐cost organic complementary semiconductor technologies that requires both efficient and stable p‐ and n‐type doping. However, in contrast to molecular p‐dopants, highly efficient n‐type dopants are commonly sensitive to rapid degradation in air due to their low ionization energies (IEs) required for electron donation, e.g., IE = 2.4 eV for tetrakis(1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidinato)ditungsten(II) (W₂(hpp)₄). Here, the air stability of various host:W₂(hpp)₄ combinations is compared by conductivity measurements and photoemission spectroscopy. A partial passivation of the n‐doping against degradation is found, with this effect identified to depend on the specific energy levels of the host material. Since host‐W₂(hpp)₄ electronic wavefunction hybridization is unlikely due to confinement of the dopant highest occupied molecular orbital (HOMO) to its molecular center, this finding is explained via stabilization of the dopant by single‐electron transfer to a host material whose energy levels are sufficiently low for avoiding further charge transfer to oxygen–water complexes. Our results show the feasibility of temporarily handling n‐doped organic thin films in air, e.g., during structuring of organic field effect transistors (OFETs) by lithography.     

On-chip, real-time, single-copy polymerase chain reaction in picoliter droplets

The first lab-on-chip system for picoliter droplet generation and PCR amplification with real-time fluorescence detection has performed PCR in isolated droplets at volumes 106 smaller than commercial real-time PCR instruments. The system utilized a shearing T-junction in a silicon device to generate a stream of monodisperse picoliter droplets that were isolated from the microfluidic channel walls and each other by the oil-phase carrier. An off-chip valving system stopped the droplets on-chip, allowing them to be thermally cycled through the PCR protocol without droplet motion. With this system, a 10-pL droplet, encapsulating less than one copy of viral genomic DNA through Poisson statistics, showed real-time PCR amplification curves with a cycle threshold of approximately 18, 20 cycles earlier than commercial instruments. This combination of the established real-time PCR assay with digital microfluidics is ideal for isolating single-copy nucleic acids in a complex environment.     

Dynamic Lean Management of the Naval Construction Process

Abstract:

The naval and private construction industries face shared problems in regard to cost over-runs and delays that may be addressed in part through improvements to the construction process. The scope of this study is to examine the naval construction process from design to implementation, with special emphasis on the role of design sharing and constructability. We use the System Dynamics methodology to model the construction process and conduct simulations to examine the impact of project management decisions. We conclude that increased constructability efforts and design sharing mitigate the impact of cost over-runs and project completion delays, and that when limited resources exist it is best to focus improvement efforts early rather than later.