Failure of hippocampectomy to facilitate classical conditioning at an optimal interstimulus interval is not due to a "ceiling effect."

Examined the effects of amphetamine injection (2 mg/kg), hippocampal lesions, and cortical lesions in 30 naive New Zealand albino rabbits during classical conditioning of the rabbit nictitating membrane response. An optimal interstimulus interval (ISI) was employed. Whereas neocortical and hippocampal damage had no significant effect on the rate of acquisition, amphetamine treatment produced a marked facilitation. A control group of amphetamine-treated Ss receiving explicitly unpaired presentations of the conditioned stimulus/stimuli (CS) and unconditioned stimulus/stimuli (UCS) failed to exceed spontaneous response rates throughout training. The failure of hippocampectomy to accelerate conditioning under an optimal ISI does not appear to be due to a ceiling effect. Rather, it is suggested that the response system is predisposed to conditioned responses of a given latency. Optimal ISIs may fall within this range. Thus, in short or long intervals, temporal aspects of the motor response must be adjusted to conform to the stimulus configuration. It appears that the hippocampus is a likely source of response modulation. Thus, loss of hippocampal input accelerates conditioning under nonoptimal intervals at the expense of proper timing. Conditioning under an optimal interval would occur at normal rates because no modulation is required. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Andreev Spectroscopy for Superconducting Phase Qubits

We propose a new method to measure the coherence time ofsuperconducting phase qubits based on the analysis of themagnetic-field dependent dc nonlinear Andreev current across ahigh-resistance tunnel contact between the qubit and a dirtymetal wire and derive a quantitative relation between thesubgap I–V characteristic and the internal correlationfunction of the qubit.     

Ascorbic Acid-Assisted Eco-friendly Synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Anode Material for High-Performance Lithium-Ion Batteries

We have synthesized NiCo₂O₄ nanoparticles (NCO NPs) using an ascorbic acid-assisted co-precipitation method for the first time. When NCO NPs are used as an anode material for lithium-ion batteries, the cell exhibits superior lithium storage properties, such as high capacity (700 mA h g^?1 after 300 cycles at 200 mA g^?1), excellent rate capabilities (applied current density range 100–1200 mA g^?1), and impressive cycling stability (at 1200 mA g^?1 up to 650 cycles). The enhanced electrochemical properties of NCO NPs are due to the nanometer dimensions which not only offers a smooth charge-transport pathway and short diffusion paths of the lithium ions but also adequate spaces for volume expansion during Li storage. Hence, this eco-friendly synthesis approach will provide a new strategy for the synthesis of various nanostructured metal oxide compounds, for energy conversion and storage systems applications.     

Miyaura Borylation and One‐Pot Two‐Step Homocoupling of Aryl Chlorides and Bromides under Solvent‐Free Conditions

Solvent‐free protocols for Miyaura borylation and the one‐pot, two‐step homocoupling of aryl halides are reported for the first time. Bis(dibenzylideneacetone)palladium(0) [Pd(dba)₂] is an optimal source of palladium for Miyaura borylation, while for one‐pot two‐step homocoupling palladium(II) acetate [Pd(OAc)₂] gives highest yields. Aryl bromides are coupled most efficiently using the DPEphos ligand. Chlorides are coupled using XPhos. The developed protocols are robust, versatile and easily reproducible on a large scale.

     

Effect of increased N use and dry periods on N<Subscript>2</Subscript>O emission from a fertilized grassland

To better understand the effects of increased N input and dry periods on soil nitrous oxide (N₂O) emission, we examined a unique data-set of weather, soil microclimate, N input, and N₂O emissions (using the eddy covariance method), measured at a fertilized grassland over the period 2003–2008. We found that the N₂O emission (11.5 kg N ha⁻¹ year⁻¹), the ratio of N₂O emission to N input (3.4), and the duration of elevated N₂O flux (57 days) in 2003 were about two times greater than those of the following years. 2003 had the highest annual N input (343 kg N ha⁻¹ year⁻¹) which exceeded the agronomical requirements for Irish grasslands (up to 306 kg ha⁻¹ year⁻¹). In the summer of 2003, the site had a significantly higher soil temperature, lower WFPS and lowest rainfall of all years. Large N₂O emission events followed rainfall after a long dry period in the summer of 2003, attributed to dominant nitrification processes. Furthermore, in the non summer periods, when temperature was lower and WFPS was higher and when there were prior N applications, lower N₂O emissions occurred and were attributed to dominant denitrification processes. Throughout the study period, the N input and soil dryness related factors (duration of WFPS under 50%, summer average WFPS, and low rainfall) showed exponential relationships with N₂O emission and the ratio of N₂O emission to N input. Based on these findings, we infer that the observed anomalously high N₂O emission in 2003 may have been caused by the combined effects of excess N input above the plant uptake rate, elevated soil temperature, and N₂O flux bursts that followed the rewetting of dry soil after an unusually long dry summer period. These results suggest that high N input above plant uptake rate and extended dry periods may cause abnormal increases in N₂O emissions.     

Improvement of predicted fine and total particulate matter (PM) composition by applying several different chemical scenarios: a winter 2005 case study

A new method using several different chemical scenarios is developed to predict chemical composition of fine (PM2.5) and total (PM10) aerosol. This method improves the accuracy of predicted PM concentrations. The Mesoscale Model version 5 (MM5) and a 3-dimensional Eulerian chemical model (CAMx4.2) are used to predict PM2.5 and PM10 concentrations using gridded input emissions (from the "Total" group) over a 48-72 h time period for Christchurch (New Zealand) for winter 2005. The aerosol concentrations are obtained for four different chemical compositions (chemical scenarios) of the input aerosol emissions. PM2.5 chemical compositions are based on previous Christchurch winter studies and from observations in other countries with similar winter pollution problems, and used in CAMx4.2 to model seven winter 2005 heavy pollution episodes. The error between observed and modelled PM2.5 concentrations is based on predictions of fine aerosol that are derived from linear regression with PM10. It is used to find the minimum difference between modelled and observed PM2.5 for an observation site located in the Christchurch residential area. Combination of the chemical scenarios with analysis of the minimum error is used to create a new complex chemical scenario. The new complex scenario is used to re-calculate all pollution episodes to obtain new values of PM with minimum error compared with observed aerosol concentrations. Mean Absolute Error of the calculated PM2.5 (for all pollution episodes) decreased from 21-24 microg m(-3) to 14-16 microg m(-3) compared with observations. The chemical composition of the modelled PM2.5 is also discussed.