Effect of context on performance to conditioned stimuli with mixed histories of reinforcement and nonreinforcement.

Five conditioned suppression experiments, with 160 Wistar rats, explored the role of the conditioning history of the conditioned stimulus (CS) in determining the effects of contextual fear on performance to the CS. Contextual fear was produced by postconditioning exposure to unconditioned stimulus/stimuli (UCS) alone in the context of conditioning; it was independently assessed with context-preference tests. When the number of reinforced and nonreinforced trials was equated across extinction, partial reinforcement, and latent inhibition procedures, only the extinction procedure produced a CS whose performance was subsequently affected (i.e., augmented) by contextual fear. Contextual fear's relatively unique augmenting effect on fear of an extinguished CS was abolished by extensive, but not by less extensive, reacquisition training. Results indicate that, depending on the CS's conditioning history, contextual fear either augments or has little effect on fear of the CS. It is suggested that augmentation by context should be viewed as the restoration of fear that is otherwise depressed by extinction. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential control by context in the inflation and reinstatement paradigms.

Examined, in 5 conditioned suppression experiments, the influence of summation between fear of the CS and the context in experimental paradigms in which the rat is exposed to UCSs following conditioning or extinction. Context-preference tests assessed contextual fear. In Exps I–III with 88 female Wistar rats, the inflation paradigm, in which fear of a CS paired with a weak UCS is enhanced by exposure to intense UCS alone, was investigated. Results show that the contextual fear that was present when the target CS was tested was reduced by presenting the intense UCSs in a different context, by exposing Ss to the context following their presentation, and by signaling the intense UCSs with a 2nd CS. In Exp IV with 32 female Wistar rats, UCS exposures following conditioning or extinction both produced contextual fear, but only fear of the extinguished CS was reinstated by that fear. In Exp V with 32 female Wistar rats, identical amounts of contextual fear reinstated fear of an extinguished CS, but not a nonextinguished CS, when the 2 types of CSs were arranged to evoke comparable amounts of fear prior to testing. It is suggested that contextual fear plays a role in the reinstatement paradigm but not in the inflation paradigm. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Robert C. Bolles (1928–1994): Obituary.

Memorializes R. C. Bolles, who was best known for research on motivation and the analysis of fear and avoidance. Perhaps Bolles's greatest contribution was his book, Theory of Motivation. The book took a biological and historical perspective and emphasized the anticipation of goals, rather than the need for them, in explaining motivated behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inhibition of pancreatic cancer growth by the dietary isoprenoids farnesol and geraniol

Fruits and vegetables have protective effects against many human cancers, including pancreatic cancer. Isoprenoids are one class of phytochemicals which have antitumor activity, but little is known about their effects on cancer of the pancreas. We tested the hypothesis that isoprenoids would inhibit the growth of pancreatic tumor cells. Significant (60–90%) inhibition of the anchorage-independent growth of human MIA PaCa2 pancreatic tumor cells was attained with 25 μM farnesol, 25 μM geranylgeraniol, 100 μM perillyl amine, 100 μM geraniol, or 300 μM perillyl alcohol. We then tested the relative in vivo antitumor activities of dietary farnesol, geraniol, and perilyl alcohol against transplanted PC-1 hamster pancreatic adenocarcinomas. Syrian Golden hamsters fed geraniol or farnesol at 20 g/kg diet exhibited complete inhibition of PC-1 pancreatic tumor growth. Both farnesol and geraniol were more potent than perillyl alcohol, which inhibited tumor growth by 50% at 40 g/kg diet. Neither body weights nor plasma cholesterol levels of animals consuming isoprenoid diets were significantly different from those of pair-fed controls. Thus, farnesol, geraniol, and perillyl alcohol suppress pancreatic tumor growth without significantly affecting blood cholesterol levels. These dietary isoprenoids warrant further investigation for pancreatic cancer prevention and treatment.     

"Getting on with life": Women's experiences and ways of coping with depression.

Explored women's experiences of depression, and in particular how women living in rural communities understand, experience, and cope with feelings of distress unaided by professional help. Participants were 15 women (aged 23–60 yrs) living in rural areas of central New Brunswick who completed a semistructured interview. The purpose of the interview was to explore their experiences of depression and their ways of coping with these experiences. The women's accounts were analyzed using thematic and discourse analysis methods. A central theme revealed in the analysis was that women's understanding of their experiences was interwoven with their attempts to live up to the ideals and practices of the "good" woman. Within this context, depressive experiences were viewed as a taken-for-granted or expected part of their everyday lives. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synaptic Resistors for Concurrent Inference and Learning with High Energy Efficiency

The fastest supercomputer, Summit, has a speed comparable to the human brain, but is much less energy‐efficient (≈10¹⁰ FLOPS W^?1, floating point operations per second per watt) than the brain (≈10¹⁵ FLOPS W^?1). The brain processes and learns from “big data” concurrently via trillions of synapses in parallel analog mode. By contrast, computers execute algorithms on physically separated logic and memory transistors in serial digital mode, which fundamentally restrains computers from handling “big data” efficiently. The existing electronic devices can perform inference with high speeds and energy efficiencies, but they still lack the synaptic functions to facilitate concurrent convolutional inference and correlative learning efficiently like the brain. In this work, synaptic resistors are reported to emulate the analog convolutional signal processing, correlative learning, and nonvolatile memory functions of synapses. By circumventing the fundamental limitations of computers, a synaptic resistor circuit performs speech inference and learning concurrently in parallel analog mode with an energy efficiency of ≈1.6 × 10¹⁷ FLOPS W^?1, which is about seven orders of magnitudes higher than that of the Summit supercomputer. Scaled‐up synstor circuits could circumvent the fundamental limitations in computers, and facilitate real‐time inference and learning from “big data” with high efficiency and speed in intelligent systems.     

Pyranoside Phosphite‐Oxazoline Ligand Library: Highly Efficient Modular P,N Ligands for Palladium‐Catalyzed Allylic Substitution Reactions. A Study of the Key Palladium Allyl Intermediates

We have screened a library of modular phosphite‐oxazoline ligands for asymmetric allylic substitution reactions. The library is efficiently prepared from the commercially available and cheap D ‐glucosamine. The introduction of a phosphite moiety into the ligand design is highly advantageous for the product outcome. Therefore, this ligand library affords good‐to‐excellent reaction rates [TOFs up to 600 mol substrate×(mol Pd×h)⁻¹] and enantioselectivities (ees up to 99%) and, at the same time, shows a broad scope for mono‐, di‐ and trisubstituted linear hindered and unhindered substrates and cyclic substrates. The NMR studies on the palladium allyl intermediates provide a deeper understanding about the effect of the ligand parameters on the origin of enantioselectivity.     

A comparison of the meat properties of pasture-fed steers, heifers, pregnant heifers and spayed heifers

Mean ultimate pH values, sarcomere lengths, cooking losses, Warner-Bratzler peak shear values and compression values for the M. longissimus dorsi (LD) did not differ significantly between heifers, spayed heifers, heifers fitted with a HEIGRO^TM device^* pregnant heifers (2 to 6 months pregnant) and steers, killed at 18 or 22 months of age, with mean carcass weights of 189 and 221 kg, respectively. This result, from animals grazed at pasture, agrees with those of others who used LD samples from lot-fed animals. It would appear that carcasses of non-pregnant heifers, spayed heifers, pregnant heifers, heifers fitted with a HIEGRO^TM device and steers of similar age and subcutaneous fat depth, do not need to be differentiated on grounds of tenderness.