Ion/Electron Induced Luminescence for Radiation Damage Process Interpretation and In Situ Material Verification

AbstractThe Research Centre for Energy, Environment and Technology (CIEMAT), Madrid, Spain, features two installations (2 MeV Van de Graaff electron accelerator and a 60kV ion implanter) specifically developed for in situ material characterization during irradiation, and focused on the study of volume and surface electrical degradation in insulating materials for fusion applications. These installations have been equipped with optical systems which permit electron and ion beam induced luminescence to be measured at the same time as recording the electrical conductivity. Recent results for combined ion-induced luminescence and surface electrical degradation experiments in alumina confirmed a correlation between conductivity changes and evolution of emission bands with irradiation dose. Similar experiments under electron irradiation in silicon carbide have also shown the usefulness of luminescence for material characterization and evaluation of radiation effects

Primitive model electrolytes. A comparison of the HNC approximation for the activity coefficient with Monte Carlo data

Accuracy of the mean activity coefficient expression (Hansen-Vieillefosse-Belloni equation), valid within the hypernetted chain (HNC) approximation, was tested in a wide concentration range against new Monte Carlo (MC) data for +1:-1 and +2:-2 primitive model electrolytes. The expression has an advantage that the excess chemical potential can be obtained directly, without invoking the time consuming Gibbs-Duhem calculation. We found the HNC results for the mean activity coefficient to be in good agreement with the machine calculations performed for the same model. In addition, the thermodynamic consistency of the HNC approximation was tested. The mean activity coefficients, calculated via the Gibbs-Duhem equation, seem to follow the MC data slightly better than the Hansen-Vieillefosse-Belloni expression. For completeness of the calculation, the HNC excess internal energies and osmotic coefficients are also presented. These results are compared with the calculations based on other theories commonly used to describe electrolyte solutions, such as the mean spherical approximation, Pitzer's extension of the Debye-H\"uckel theory, and the Debye-H\"uckel limiting law.Comment: 15 pages, 6 figure

Divisive Normalization from Wilson-Cowan Dynamics

Divisive Normalization and the Wilson-Cowan equations are influential models of neural interaction and saturation [Carandini and Heeger Nat.Rev.Neurosci. 2012; Wilson and Cowan Kybernetik 1973]. However, they have not been analytically related yet. In this work we show that Divisive Normalization can be obtained from the Wilson-Cowan model. Specifically, assuming that Divisive Normalization is the steady state solution of the Wilson-Cowan differential equation, we find that the kernel that controls neural interactions in Divisive Normalization depends on the Wilson-Cowan kernel but also has a signal-dependent contribution. A standard stability analysis of a Wilson-Cowan model with the parameters obtained from our relation shows that the Divisive Normalization solution is a stable node. This stability demonstrates the consistency of our steady state assumption, and is in line with the straightforward use of Divisive Normalization with time-varying stimuli. The proposed theory provides a physiological foundation (a relation to a dynamical network with fixed wiring among neurons) for the functional suggestions that have been done on the need of signal-dependent Divisive Normalization [e.g. in Coen-Cagli et al., PLoS Comp.Biol. 2012]. Moreover, this theory explains the modifications that had to be introduced ad-hoc in Gaussian kernels of Divisive Normalization in [Martinez et al. Front. Neurosci. 2019] to reproduce contrast responses. The proposed relation implies that the Wilson-Cowan dynamics also reproduces visual masking and subjective image distortion metrics, which up to now had been mainly explained via Divisive Normalization. Finally, this relation allows to apply to Divisive Normalization the methods which up to now had been developed for dynamical systems such as Wilson-Cowan networks

Työntekijän itseohjautuvuus ja sen johtaminen luovassa asiantuntijaorganisaatiossa

Tiivistelmä. Tutkimuksen tarkoitus on selvittää yksilön itseohjautuvuuden merkitystä ja sen johtamista luovassa asiantuntijaorganisaatiossa. Aihevalintani perustuu työntekijän itseohjautuvuuden merkitykseen organisaatiolle sekä omaan kiinnostuneisuuteeni itseohjautuvaa työskentelytapaa kohtaan. Tutkimus on toteutettu kirjallisuuskatsauksen ja teemahaastattelun avulla. Haastattelut tehtiin viidelle työntekijälle valitussa kohdeyrityksessä. Kohdeyritys on pärjännyt hyvin vuosittain järjestettävässä henkilöstöjohtamista mittaavassa kilpailussa ja tunsin yrityksessä työskenteleviä, mielestäni itseohjautuvia henkilöitä. Tämä herätti mielenkiintoni tehdä tutkimus juuri kyseiseen yritykseen. Haastateltavat kertoivat muun muassa päätymisestään alalle, työskentelytavoistaan, työn vaatimuksista, koetusta johtamisen tasosta kohdeyrityksessä ja asioista, jotka vaikuttivat heidän motivaatioonsa. Pyrin haastattelukysymyksillä luomaan kuvan itseohjautuvasta työntekijästä, hänen tavastaan suorittaa työnsä sekä toiveistaan itseohjautumisen mahdollistamiseksi. Tutkimuksen tuloksista kävi ilmi, että itseohjatuvuudella on merkitystä organisaation menestymiselle ja kilpailukyvylle. Itseohjautuvuutta voidaan johtaa muun muassa osallistavan organisaatiokulttuurin, joustavuuden, kannustavan ilmapiirin sekä innostavien arvojen avulla. Tutkimuksessa kävi ilmi, että etenkin luovan asiantuntijaorganisaation johtaminen tarjoaa työkaluja itseohjautuvuuden lisäämiseksi tämän tyyppisessä työssä. Tutkimuksen kohteena olevan yrityksen työntekijät kokivat työnantajansa onnistuneen itseohjautuvuuden tukemisessa. Tutkimuksen mukaan työympäristöllä ei ole yhtä suurta vaikutusta motivaatioon ja itseohjautuvuuteen kuin oman työn arvostamisella, vapaudella, hyvällä tiimihengellä ja työtehtävien riittävällä haasteellisuudella. Tutkimustulokset osoittivat myös, että johdolla tulisi olla aikaa luoville asiantuntijoilleen. Tämä lisää enemmän motivaatiotasoa, kuin ulkoisten motivaattoreiden, kuten esimerkiksi rahallisten korvausten, poistaminen. Tutkimustuloksia ei voi liikaa yleistää, sillä haastattelun kohteena oli pieni yritys, joka oli jo lähtötilanteessa kunnostautunut hyvässä johtamisen tasossa. Myös haastateltavat valittiin heidän osoittamansa itseohjautuvuuden perusteella. Tämä ohjasi osaltaan tutkimuksen tuloksia. Toisaalta tutkimus osoittaa itseohjautuvuuden ilmenemismuotoja yksilön työskentelytavassa ja luovien asiantuntijoiden vaatimuksia työlleen

100% RAG: Syracuse School of Architecture, Student Newspaper, Volume 1, Number 3

100% RAG: Syracuse School of Architecture, Student Newspaper, Volume 1, Number 3. Student newsletter from student contributors of Syracuse School of Architecture in 1976

Towards a Functional Explanation of the Connectivity LGN - V1

The principles behind the connectivity between LGN and V1 are not well understood. Models have to explain two basic experimental trends: (i) the combination of thalamic responses is local and it gives rise to a variety of oriented Gabor-like receptive felds in V1 [1], and (ii) these filters are spatially organized in orientation maps [2]. Competing explanations of orientation maps use purely geometrical arguments such as optimal wiring or packing from LGN [3-5], but they make no explicit reference to visual function. On the other hand, explanations based on func- tional arguments such as maximum information transference (infomax) [6,7] usually neglect a potential contribution from LGN local circuitry. In this work we explore the abil- ity of the conventional functional arguments (infomax and variants), to derive both trends simultaneously assuming a plausible sampling model linking the retina to the LGN [8], as opposed to previous attempts operating from the retina. Consistently with other aspects of human vi- sion [14-16], additional constraints should be added to plain infomax to understand the second trend of the LGN-V1 con- nectivity. Possibilities include energy budget [11], wiring constraints [8], or error minimization in noisy systems, ei- ther linear [16] or nonlinear [14, 15]. In particular, consideration of high noise (neglected here) would favor the redundancy in the prediction (which would be required to match the relations between spatially neighbor neurons in the same orientation domain)

Multi-band metasurface-driven surface-enhanced infrared absorption spectroscopy for improved characterization of in-situ electrochemical reactions

Surface-enhanced spectroscopy techniques are the method-of-choice to characterize adsorbed intermediates occurring during electrochemical reactions, which are crucial in realizing a green sustainable future. Characterizing species with low coverages or short lifetimes have so far been limited by low signal enhancement. Recently, metasurface-driven surface-enhanced infrared absorption spectroscopy (SEIRAS) has been pioneered as a promising narrowband technology to study single vibrational modes of electrochemical interfaces during CO oxidation. However, many reactions involve several species or configurations of adsorption that need to be monitored simultaneously requiring reproducible and broadband sensing platforms to provide a clear understanding of the underlying electrochemical processes. Here, we experimentally realize multi-band metasurface-driven SEIRAS for the in-situ study of electrochemical CO2 reduction on a Pt surface. We develop an easily reproducible and spectrally-tunable platinum nano-slot metasurface. Two CO adsorption configurations at 2030 cm-1 and 1840 cm-1 are locally enhanced as a proof of concept that can be extended to more vibrational bands. Our platform provides a 41-fold enhancement in the detection of characteristic absorption signals compared to conventional broadband electrochemically roughened platinum films. A straightforward methodology is outlined starting by baselining our system in CO saturated environment and clearly detecting both configurations of adsorption, in particular the hitherto hardly detectable CO bridge configuration. Then, thanks to the signal enhancement provided by our platform, we find that the CO bridge configuration on platinum does not play a significant role during CO2 reduction in an alkaline environment. We anticipate that our technology will guide researchers in developing similar sensing platforms.Comment: 21 pages, 4 figure