Productividad de autores y revistas en el ��rea de la excepcionalidad : un an��lisis bibliom��trico a trav��s del Current Index to Journals in Education.

Delimitar el ��rea de las dificultades del aprendizaje y conocer la panor��mica actualizada de la investigaci��n en esta ��rea. El Current Index Journal Education (CIJE): todos los abstracts aparecidos bajo el ep��grafe handicapped and gifted children, en el per��odo 1980-1984, ambos inclusive. Estudio de la productividad de revistas. Impacto, vida media y ranking de las m��s productivas. Estudio de productividad de autores. An��lisis de los autores m��s productivos. CIJE. Investigaci��n bibliom��trica: ley de Lotka, ley de dispersi��n de Bradford, ��ndice de productividad total, ��ndice de productividad fraccionaria, agrupamiento criterial de Crane. En cuanto a las revistas se codifican 81, con un total de 7287 art��culos, siendo la media global de 90 art��culos por revista. Una sola revista publica el 70 por ciento de la producci��n total. Con la ley de Bradford se hallan cuatro ��reas de productividad: la primera ��rea la forman cinco revistas que publican una media de 371'6 art��culos. La segunda la forman 15 t��tulos con una media de 184'4 art��culos, la tercera la forman 21 t��tulos con una media de 90 art��culos. La cuarta la forman 40 t��tulos con una media de 42'2 art��culos. Las revistas de las dos primeras ��reas se publican todas en EEUU, excepto una. Para la jerarquizaci��n de autores se recurre al modelo de Crane: se encuentran 29 autores a los que incluir en grandes productores, 150 en el de productores moderados, 1220 aparecen como aspirantes y 5'190 como transeuntes. Los autores m��s productivos son: Frith, G., Kavale, K. A., Chandler, H. N., Torrance, E. Paul, Salend, S. J., Algozzine, B., Csapo, M., Forness, S., Stainback, W., Stainback, S., Ysseldike, J. Giordano, G. y Treffinger, D. Ser��a interesante realizar un estudio de las ��reas tem��ticas.

Air-earth current density measurements at Lerwick; implications for seasonality in the global electric circuit

Atmospheric electricity measurements were made at Lerwick Observatory in the Shetland Isles (60��09���N, 1��08���W) during most of the 20th century. The Potential Gradient (PG) was measured from 1926 to 84 and the air-earth conduction current (Jc) was measured during the final decade of the PG measurements. Daily Jc values (1978���1984) observed at 15 UT are presented here for the first time, with independently-obtained PG measurements used to select valid data. The 15 UT Jc (1978���1984) spans 0.5���9.5 pA/m2, with median 2.5 pA/m2; the columnar resistance at Lerwick is estimated as 70 P��m2. Smoke measurements confirm the low pollution properties of the site. Analysis of the monthly variation of Lerwick Jc data shows that winter (DJF) Jc is significantly greater than the summer (JJA) Jc by 20%. The Lerwick atmospheric electricity seasonality differs from the global lightning seasonality, but Jc has a similar seasonal phasing to that observed in Nimbostratus clouds globally, suggesting a role for non-thunderstorm rain clouds in the seasonality of the global circuit.

Nerve terminal GABAA receptors activate Ca2+/calmodulin-dependent signaling to inhibit voltage-gated Ca2+ influx and glutamate release

-Aminobutyric acid type A (GABAA) receptors, a family of Cl-permeable ion channels, mediate fast synaptic inhibition as postsynaptically enriched receptors for -aminobutyric acid at GABAergic synapses. Here we describe an alternative type of inhibition mediated byGABAA receptors present on neocortical glutamatergic nerve terminals and examine the underlying signaling mechanism(s). By monitoring the activity of the presynaptic CaM kinase II/synapsin I signaling pathway in isolated nerve terminals, we demonstrate that GABAA receptor activation correlated with an increase in basal intraterminal [Ca2]i. Interestingly, this activation of GABAA receptors resulted in a reduction of subsequent depolarization-evoked Ca2 influx, which thereby led to an inhibition of glutamate release. To investigate how the observed GABAA receptor-mediated modulation operates, we determined the sensitivity of this process to the Na-K-2Cl cotransporter 1 antagonist bumetanide, as well as substitution of Ca2 with Ba2, or Ca2/calmodulin inhibition by W7. All of these treatments abolished the modulation by GABAA receptors. Application of selective antagonists of voltage-gated Ca2 channels (VGCCs) revealed that the GABAA receptor-mediated modulation of glutamate release required the specific activity of L- and R-type VGCCs. Crucially, the inhibition of release by these receptors was abolished in terminals isolated from R-type VGCC knock-out mice. Together, our results indicate that a functional coupling between nerve terminal GABAA receptors and L- or R-type VGCCs is mediated by Ca2/calmodulin-dependent signaling. This mechanism provides a GABA-mediated control of glutamatergic synaptic activity by a direct inhibition of glutamate release.

Vertical current flow through extensive layer clouds

The global atmospheric electrical circuit sustains a vertical current density between the ionosphere and the Earth's surface, the existence of which is well-established from measurements made in fair-weather conditions. In overcast, but non-thunderstorm, non-precipitating conditions, the current travels through the cloud present, despite cloud layers having low electrical conductivity. For extensive layer clouds, this leads to space charge at the upper and lower cloud boundaries. Using a combination of atmospheric electricity and solar radiation measurements at three UK sites, vertical current measurements have been categorised into clear, broken, and overcast cloud conditions. This approach shows that the vertical ���fair weather��� current is maintained despite the presence of cloud. In fully overcast conditions with thick cloud, the vertical current is reduced compared to thin cloud overcast conditions, associated with the cloud's resistance contributions. Contribution of cloud to the columnar resistance depends both on cloud thickness, and the cloud's height.

Modelling monsoons: understanding and predicting current and future behaviour

The global monsoon system is so varied and complex that understanding and predicting its diverse behaviour remains a challenge that will occupy modellers for many years to come. Despite the difficult task ahead, an improved monsoon modelling capability has been realized through the inclusion of more detailed physics of the climate system and higher resolution in our numerical models. Perhaps the most crucial improvement to date has been the development of coupled ocean-atmosphere models. From subseasonal to interdecadal time scales, only through the inclusion of air-sea interaction can the proper phasing and teleconnections of convection be attained with respect to sea surface temperature variations. Even then, the response to slow variations in remote forcings (e.g., El Ni��o���Southern Oscillation) does not result in a robust solution, as there are a host of competing modes of variability that must be represented, including those that appear to be chaotic. Understanding the links between monsoons and land surface processes is not as mature as that explored regarding air-sea interactions. A land surface forcing signal appears to dominate the onset of wet season rainfall over the North American monsoon region, though the relative role of ocean versus land forcing remains a topic of investigation in all the monsoon systems. Also, improved forecasts have been made during periods in which additional sounding observations are available for data assimilation. Thus, there is untapped predictability that can only be attained through the development of a more comprehensive observing system for all monsoon regions. Additionally, improved parameterizations - for example, of convection, cloud, radiation, and boundary layer schemes as well as land surface processes - are essential to realize the full potential of monsoon predictability. A more comprehensive assessment is needed of the impact of black carbon aerosols, which may modulate that of other anthropogenic greenhouse gases. Dynamical considerations require ever increased horizontal resolution (probably to 0.5 degree or higher) in order to resolve many monsoon features including, but not limited to, the Mei-Yu/Baiu sudden onset and withdrawal, low-level jet orientation and variability, and orographic forced rainfall. Under anthropogenic climate change many competing factors complicate making robust projections of monsoon changes. Absent aerosol effects, increased land-sea temperature contrast suggests strengthened monsoon circulation due to climate change. However, increased aerosol emissions will reflect more solar radiation back to space, which may temper or even reduce the strength of monsoon circulations compared to the present day. Precipitation may behave independently from the circulation under warming conditions in which an increased atmospheric moisture loading, based purely on thermodynamic considerations, could result in increased monsoon rainfall under climate change. The challenge to improve model parameterizations and include more complex processes and feedbacks pushes computing resources to their limit, thus requiring continuous upgrades of computational infrastructure to ensure progress in understanding and predicting current and future behaviour of monsoons.

A narrow band pulsed eddy current instrument for materials testing

The principles of operation of an experimental prototype instrument known as J-SCAN are described along with the derivation of formulae for the rapid calculation of normalized impedances; the structure of the instrument; relevant probe design parameters; digital quantization errors; and approaches for the optimization of single frequency operation. An eddy current probe is used As the inductance element of a passive tuned-circuit which is repeatedly excited with short impulses. Each impulse excites an oscillation which is subject to decay dependent upon the values of the tuned-circuit components: resistance, inductance and capacitance. Changing conditions under the probe that affect the resistance and inductance of this circuit will thus be detected through changes in the transient response. These changes in transient response, oscillation frequency and rate of decay, are digitized, and then normalized values for probe resistance and inductance changes are calculated immediately in a micro processor. This approach coupled with a minimum analogue processing and maximum of digital processing has advantages compared with the conventional approaches to eddy current instruments. In particular there are: the absence of an out of balance condition and the flexibility and stability of digital data processing.

The modelling of electrical current NDT methods and its application to weld testing

Discussion of the numerical modeling of NDT methods based on the potential drop and the disruption of power lines to describe the nature, importance and application of modeling. La 1��re partie est consacr��e aux applications aux contr��les par courants de Foucault. The first part is devoted to applications for inspection by eddy currents.

The modelling of electrical current NDT methods and its application to weld testing

Control by voltage drop DC. Contr��le par chute de potentiel de courant alternatif. Control by voltage drop AC.

Current deflection at cracks: some insights from modelling

Eddy current testing by current deflection detects surface cracks and geometric features by sensing the re-routing of currents. Currents are diverted by cracks in two ways: down the walls, and along their length at the surface. Current deflection utilises the latter currents, detecting them via their tangential magnetic field. Results from 3-D finite element computer modelling, which show the two forms of deflection, are presented. Further results indicate that the current deflection technique is suitable for the detection of surface cracks in smooth materials with varying material properties.