Conditional Discriminative Functions of Meaningful Stimuli and Enhanced Equivalence Class Formation

Two experiments explored how the formation of two 3-node, 5- member equivalence classes by college students was influenced by the prior acquisition of conditional discriminative functions by one of the abstract stimuli, designated as C, in the class. In Experiment 1, participants in the GR-0, GR-1, and GR-5 groups attempted to form classes after mastering 0, 1 or 5 conditional relations between C and abstract stimuli that were not included in the to-be-formed classes. Participants in the GR-many group attempted to form classes that contained four abstract stimuli and one meaningful, familiar picture that served as the C stimulus. In Experiment 1, the percentage of participants who formed classes in the GR-0, -1, and -5 groups was a direct function of the number of conditional relations that C formed with other stimuli in preliminary training, with the GR-5 group producing a yield similar to that produced when a meaningful picture was the C stimulus (i.e., in the GR-many condition). Two factors differentiated GR-1 and GR-5 pre-training: the number of conditional relations trained to C, and the number of training trials in the presence of the C stimuli. Experiment 2 found that the increase in yield produced by GR-5 was due to number of trained C-based relations and not to the amount of training. Furthermore, Experiment 2 showed that enhancement of class formation after GR-1 pre-training is not improved by linking the C stimulus with a meaningful picture instead of a meaningless stimulus. These results along with recently published research support the view that the class enhancing effect of meaningful stimuli can be attributed to their acquired conditional discriminative and simple discriminative functions, in addition to their connotative and denotative functions

Quantum transport in weakly coupled superlattices at low temperature

We report on the study of the electrical current flowing in weakly coupled superlattice (SL) structures under an applied electric field at very low temperature, i.e. in the tunneling regime. This low temperature transport is characterized by an extremely low tunneling probability between adjacent wells. Experimentally, I(V) curves at low temperature display a striking feature, i.e a plateau or null differential conductance. A theoretical model based on the evaluation of scattering rates is developed in order to understand this behaviour, exploring the different scattering mechanisms in AlGaAs alloys. The dominant interaction in usual experimental conditions such as ours is found to be the electron-ionized donors scattering. The existence of the plateau in the I(V) characteristics is physically explained by a competition between the electric field localization of the Wannier-Stark electron states in the weakly coupled quantum wells and the electric field assisted tunneling between adjacent wells. The influence of the doping concentration and profile as well as the presence of impurities inside the barrier are discussed

THE SEPTEMBER 2013 RAIN AND FLOOD EVENTS IN THE FLAM’S VALLEY BASIN. CAUSES, CHARACTERISTICS AND THEIR IMPACT UPON THE ENVIRONMENT

Between 11.09 and 14.09 2013 the north-eastern part of Tulcea County, especially the areas located around Somova village was affected by heavy, torrential rainfall that totalized over 30 mm/sq m and triggered dangerous hydrological phenomena (important slope, stream and river flows). As a result of these heavy downpours, Flam’s Valley was affected by an exceptional flash-flood which measured a peak discharge that reached a 1% exceeding probability. Another destructive characteristic of the weather phenomena that occurred in September 2013 was that the heavy rain was accompanied by violent gusty winds that resembled tornado-like features, bringing serious threat to houses, households and roads. In this paper we have analyzed the weather features that produced the September 2013 flash flood from both a spatial and a temporal perspective. The hydrological analysis focuses on the peak discharge that was recorded during the flash flood as well as on the characteristics elements of the topographic profiles. The paper ends with a brief presentation of the consequences that the weather and hydrological phenomena had upon the environment and population as well

Does 'relationship intelligence' make big brains in birds?

Lately, Emery et al. developed a bird-specific modification of the “social brain hypothesis”, termed “relationship intelligence hypothesis”. Although the idea may be valuable, we doubt that it is supported by sufficient evidence and critically discuss some of the arguments raised by the authors in favour of their new idea

Surface Reaction Films from Amine-Based Organic Friction Modifiers and Their Influence on Surface Fatigue and Friction

Surface reactive additives are crucial in the lubrication of surfaces experiencing cyclic contact. The combination of additives in the lubricant, on the material surface and the complex tribo-contact conditions hinders the design of additive packages which can simultaneously protect steel surfaces from wear and fatigue. Amine-based Organic Friction Modifiers (OFMs) influence the tribological performance of steel surfaces. This study investigates the tribochemical impact of three amine-based OFMs in combination with Zinc DialkylDithioPhosphate (ZDDP) on tribological performance, particularly surface fatigue, for steel surfaces in severe rolling–sliding contacts. The thickness of reaction films was tracked throughout experiments and the chemistry of reaction films was examined using X-ray Photoelectron Spectroscopy (XPS). Results highlight the impact of the OFM polar moiety on tribological performance and its influence on chemical composition of tribo-reaction films and their formation kinetics. The combination of selected OFMs with ZDDP reduces frictional forces and can mitigate surface fatigue under certain conditions

Incidental imaging findings of congenital rib abnormalities – a case series and review of developmental concepts

Background: Congenital rib abnormalities are found in approximately 2% of the general population. Usually, they occur in isolation and are rarely symptomatic, but they can also be associated with other malformations. Materials and methods: We reviewed imaging examinations performed over a period of 2 years (2014–2015), enabling us to identify isolated rib abnormalities in 6 adult patients. Results: The case series consisted in 3 cases with bilateral cervical ribs and 1 case each with bifid rib, costal fusion and rib pseudarthrosis. In all patients, the costal anomalies were discovered incidentally. All rib malformations were detected at thoracic radiography, except for the rib pseudarthrosis, which was identified at computed tomography (CT) scan. Differential diagnosis was made between cer­vical ribs and abnormalities of the C7 transverse process and of the first rib, while the other costal malformations were distinguished from tumoural, traumatic or inflammatory lesions of the chest wall, lung and pleura. Considering the existing knowledge on rib development, we suggest a classification of the most common types of rib malformations in three categories: (I) results of homeotic transforma­tion, referring to numerical aberrations; (II) segmentation errors, including costal fusion and bridging; (III) anomalies of resegmentation, resulting in bifid ribs. Conclusions: It is important that radiologists are familiarised with the imaging features of rib abnormalities, since these anomalies can be misinterpreted as lesions with different implications. We are convinced that the developmental classification proposed in this paper can contribute to a better understanding of this pathology. (Folia Morphol 2018; 77, 2: 386–392