Context- but not familiarity-dependent forms of object recognition are impaired following excitotoxic hippocampal lesions in rats.

Dual-process models of recognition memory in animals propose that recognition memory is supported by two independent processes that reflect the operation of distinct brain structures: a familiarity process that operates independently of the hippocampus and a context-dependent (episodic) memory process that is dependent on the hippocampus. A novel variant of an object recognition procedure was used to examine this proposal. Healthy rats showed a preference for exploring a novel object rather than a familiar object: a familiarity-dependent recognition effect. They also showed a preference for exploring a familiar object that was presented in a different spatiotemporal context rather than a familiar object that was presented either in a different spatial or temporal context: a context-dependent form of recognition that is sensitive to "what" object has been presented "where" and "when." Rats with excitotoxic hippocampal lesions showed the familiarity-dependent but not the context-dependent form of recognition. The results provide support for dual-process theories of recognition memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new low temperature approach to developing mesoporosity in metal-doped carbons for adsorption and catalysis

Key factors in achieving effective adsorption are the size of the pores relative to those of the adsorbate molecules and often the presence of small metal particles which can confer catalytic activity. While microporous carbons are excellent adsorbents for small molecules they are not as effective for larger species. A new low temperature approach to activation using an oxygen gas pulsing technique to achieve a carbon with controllable meso/micropore structure is described which also minimises metal sintering. The porosity of the samples was analysed by nitrogen adsorption at 77 K. Microporous metal-doped ASC carbon showed significant increases in the level of mesoporosity, its mesopore volume increasing from 0.06 to 0.24 cm³ g⁻¹. However, undoped BPL carbon treated under the same conditions remained unchanged. The catalytic effect of the metals in the ASC carbon is thought to account for the observed mesopore development. At the temperatures used, a continuous oxidative activation yielded no pore widening in either carbon, suggesting that the gas pulsing method is far more effective in increasing mesopore sizes.     

Comparison of Nd 1.06 and 1.33 µm operation in various hosts

Performances of Nd in various hosts including Nd:YAG, Nd:YLF, Nd:BEL, and Nd:Cr:GSGG were characterized and compared for operation on the nominal 1.06 μm and 1.33 μm transitions. Comparison included continuous mode operation, normal mode operation,Q-switched operation, and gain measurements. Continuous lasing of Nd:Cr:GSGG under lamp pumping is reported for what may be the first time. Characterization included operation with different mirror reflectivities to obtain the internal losses, measurement of the upper laser level lifetime, measurement of the beam quality of the lasers operating under nominally similar circumstances, and measurement of the wavelength. These measurements should provide a comparison of the various Nd hosts under similar circumstances for a wide variety of operational modes and at both wavelengths of interest.     

Preferences in human mate selection.

Examined the consequences of mate preferences for the processes of assortative mating and sexual selection. In Study 1, 92 married couples (aged 18–40 yrs) completed measures such as the California Psychological Inventory, Eysenck Personality Questionnaire, and Personal Attributes Questionnaire. Data were used to identify (a) the mate characteristics that were consensually more and less desired, (b) the mate characteristics that showed strong sex differences in their preferred value, (c) the degree to which married couples were correlated in selection preferences, and (d) the relations between expressed preferences and the personality and background characteristics of obtained spouses. Marital preference factors included Religious, Kind/Considerate, Artistic/Intelligent, and Easygoing/Adaptable. Study 2, with 100 unmarried undergraduates, replicated the sex differences and consensual ordering of mate preferences found in Study 1, using a different methodology. Alternative hypotheses are presented to account for the replicated sex differences in preferences for attractiveness and earning potential. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Machinability improvement of titanium alloy (Ti–6Al–4V) via LAM and hybrid machining

Titanium alloy (Ti–6Al–4V) is one of the materials extensively used in the aerospace industry due to its excellent properties of high specific strength and corrosion resistance, but it also presents problems wherein it is an extremely difficult material to machine. The cost associated with titanium machining is also high due to lower cutting speeds (<60 m/min) and shorter tool life. Laser-assisted machining (LAM) and consequently hybrid machining is utilized to improve the tool life and the material removal rate. The effectiveness of the two processes is studied by varying the tool material and material removal temperature while measuring the cutting forces, specific cutting energy, surface roughness, microstructure and tool wear. Laser-assisted machining improved the machinability of titanium from low (60 m/min) to medium-high (107 m/min) cutting speeds; while hybrid machining improved the machinability from low to high (150–200 m/min) cutting speeds. The optimum material removal temperature was established as 250 °C. Two to three fold tool life improvement over conventional machining is achieved for hybrid machining up to cutting speeds of 200 m/min with a TiAlN coated carbide cutting tool. Tool wear predictions based on 3-D FEM simulation show good agreement with experimental tool wear measurements. Post-machining microstructure and microhardness profiles showed no change from pre-machining conditions. An economic analysis, based on estimated tooling and labor costs, shows that LAM and the hybrid machining process with a TiAlN coated tool can yield an overall cost savings of ～30% and ～40%, respectively.     

Conditioning of ictal and interictal behaviors in rats by amygdala kindling: Context as the conditional stimulus.

The authors showed that conditional effects of the stimulation environment modulate both the ictal and interictal behaviors of rats subjected to amygdala kindling. Rats received 53 stimulations to the left basolateral amygdala in 1 conditional stimulus (CS) context (CS+) and 53 sham stimulations (the stimulation lead was attached but no current was delivered) in another context (CS-), quasirandomly over 54 days. Three kinds of conditional effects were observed, First, after several stimulations, less ambulatory activity, more freezing, and less rearing reliably occurred in the CS + context than in the CS context. Second, after 45 stimulations, all of the rats chose the CS - context over the CS + context in a conditioned place preference test. Third, when the rats were finally stimulated in the CS- context, their motor seizures were less severe: Latencies were longer, motor seizures were shorter, convulsive patterns were of a lower class, and there were fewer falls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amplified spontaneous emission-application to Nd:YAG lasers

Amplified spontaneous emission can seriously degrade the Q-switched performance of a strong four-level transition such as the 1.064 μm Nd:YAG transition or can even prevent oscillation on a weaker quasi-four-level transition such as the 0.946-μm Nd:YAG transition. To characterize, and thus be able to mitigate, amplified spontaneous emission, a closed-form model is developed. By employing a closed-form solution, the differential equations describing both the evolution and decay of the upper laser manifold population density can be solved exactly. An advantage of this model is the separation of the spectral and spatial portions of amplified spontaneous emission. Gain measurements, as a function of time and pump energy, are compared with the model and good agreement is found. With these principles in mind, a flashlamp-pumped Nd:YAG laser was designed to operate at 0.936 μm. At room temperature, a threshold of 12 J and a slope efficiency of 0.009 was achieved     

16-channel parallel optical interconnect demonstration with an InGaAs/InP MQW modulator array

A 4*4 planar array of MQW surface modulators driven by standard high-speed CMOS has been demonstrated in an experimental parallel-interconnect system. Transition times were fast enough for 100 Mbit/s operation and the potential exists to increase array dimensions to include hundreds of devices and transmission rates to many Gbit/s.<>