Spatial Proximity and Complementarities in the Trading of Tacit Knowledge

We model knowledge-trading coalitions in which the transfer of tacit knowledge is unverifiable and requires face-to-face contact, making spatial proximity important. When there are sufficient “complementarities” in knowledge exchange, successful exchange is facilitated if firms can meet in a central location,thereby economizing on travel costs. When complementarities are small,however, a central location may be undesirable because it is more vulnerable to cheating than a structure involving bilateral travel between firms. We believe that our framework may help explain the structure and stability of multimember technology trading coalitions such as Sematech and Silicon Valley.Tacit Knowledge, Clusters, Knowledge Trading, Complementarities. Spatial Proximity

Monitoring the operation of a graphene transistor in an integrated circuit by XPS

One of the transistors in an integrated circuit fabricated with graphene as the current controlling element, is investigated during its operation, using a chemical tool, XPS. Shifts in the binding energy of C1s are used to map out electrical potential variations, and compute sheet resistance of the graphene layer, as well as the contact resistances between the metal electrodes. Measured shifts depend on lateral positions probed, as well as on polarity and magnitude of the gate-voltage. This non-contact and chemically specific characterization can be pivotal in diagnoses. © 2016 Elsevier B.V

X-ray photoelectron spectroscopy for identification of morphological defects and disorders in graphene devices

The progress in the development of graphene devices is promising, and they are now considered as an option for the current Si-based electronics. However, the structural defects in graphene may strongly influence the local electronic and mechanical characteristics. Although there are well-established analytical characterization methods to analyze the chemical and physical parameters of this material, they remain incapable of fully understanding of the morphological disorders. In this study, x-ray photoelectron spectroscopy (XPS) with an external voltage bias across the sample is used for the characterization of morphological defects in large area of a few layers graphene in a chemically specific fashion. For the XPS measurements, an external +6 V bias applied between the two electrodes and areal analysis for three different elements, C1s, O1s, and Au4f, were performed. By monitoring the variations of the binding energy, the authors extract the voltage variations in the graphene layer which reveal information about the structural defects, cracks, impurities, and oxidation levels in graphene layer which are created purposely or not. Raman spectroscopy was also utilized to confirm some of the findings. This methodology the authors offer is simple but provides promising chemically specific electrical and morphological information. � 2016 American Vacuum Society

Electrical properties from photoinduced charging on Cd-doped (100) surfaces of CuInSe2 epitaxial thin films

The photoresponse of Cd-doped CuInSe2 (CIS) epitaxial thin films on GaAs(100) was studied using x-ray photoelectron spectroscopy under illumination from a 532 nm laser between sample temperatures of 28-260 °C. The initial, air-exposed surface shows little to no photoresponse in the photoelectron binding energies, the Auger electron kinetic energies or peak shapes. Heating between 50 and 130 °C in the analysis chamber results in enhanced n-type doping at the surface and an increased light-induced binding energy shift, the magnitude of which persists when the samples are cooled to room temperature from 130 °C but which disappears when cooling from 260 °C. Extra negative charge trapped on the Cu and Se atoms indicates deep trap states that dissociate after cooling from 260 °C. Analysis of the Cd modified Auger parameter under illumination gives experimental verification of electron charging on Cd atoms thought to be shallow donors in CIS. The electron charging under illumination disappears at 130 °C but occurs again when the sample is cooled to room temperature. © 2016 American Vacuum Society

Genetic analysis of rab7 mutants in zebrafish

Vascular network formation requires the fusion of newly formed blood vessels and the emergence of a patent lumen between the newly established connections so that blood flow can start. Lumen formation has been shown to depend on the late endosomal/lysosomal pathway in various organs of animal tubular systems. Here, we identified a late endosomal/lysosomal vesicular fraction (Rab7/Lamp2) in early zebrafish angiogenic sprouts, which appears to contribute to apical membrane growth during lumen formation. To study the effect of the late endocytic pathway on vascular development, we generated mutant alleles for all three rab7 genes in zebrafish ( rab7a, rab7ba, rab7bb ). All rab7 genes are expressed in wild-type zebrafish and we did not detect any compensatory effects by the other rab7 isoforms in single knockout mutants, which were all viable. Only the triple mutant was lethal suggesting some functional redundancy. However, the different rab7 isoforms fulfil also at least partially independent functions because eggs laid from mothers lacking two rab7 ( rab7a and/or rab7bb ). showed reduced survival and contained enlarged yolk granules, suggesting maternal contribution of these two rab7 . Finally, we observed minor effects on lumen formation in embryos which still express one copy of rab7 . Our results support the notion that the late endocytic/lysosomal compartment contributes to lumen expansion

Gate-tunable photoemission from graphene transistors

In this Letter, we report gate-tunable X-ray photoelectron emission from back-gated graphene transistors. The back-gated transistor geometry allows us to study photoemission from graphene layer and the dielectric substrate at various gate voltages. Application of gate voltage electrostatically dopes graphene and shifts the binding energy of photoelectrons in various ways depending on the origin and the generation mechanism(s) of the emitted electrons. The gate-induced shift of the Fermi energy of graphene alters the binding energy of the C 1s electrons, whereas the electric field of the gate electrodes shift the binding energy of core electrons emitted from the gate dielectric underneath the graphene layer. The gradual change of the local potential through depths of the gate dielectric provides quantitative electrical information about buried interfaces. Our results suggest that gate-tunable photoemission spectra with chemically specific information linked with local electrical properties opens new routes to elucidating operation of devices based especially on layered materials. © 2014 American Chemical Society

XPS enables visualization of electrode potential screening in an ionic liquid medium with temporal- and lateral-resolution

We present an X-ray photoelectron spectroscopic (XPS) investigation of potential screening across two gold electrodes fabricated on a porous polymer surface which is impregnated with the ionic liquid (IL) N-N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethanesulfonyl)imide [DEME-TFSI]. The IL provides a sheet of conducting layers to the insulating polymer film, and allows monitoring charging and screening dynamics at the polymer + IL/vacuum interface in a laterally resolved fashion across the electrodes. Time-resolved measurements are also implemented by recording F1s peaks of the IL, while imposing 10 mHz square-wave (SQW) pulses across the two electrodes in a source-drain geometry. Variations in the F1s binding energy reflect directly the transient local electrical potential, and allow us to visualize screening of the otherwise built-in local voltage drop on and across the metal electrodes in the range of millimeters. Accordingly, the device is partitioned into two oppositely polarized regions, each following polarization of one electrode through the IL medium. On the other extreme, upon imposing relatively fast 1 kHz SQW pulses the charge screening is prevented and the device is brought to assume a simple resistor role. A simple equivalent circuit model also reproduces the observed voltage transients qualitatively. The presented structure and variants of XPS measurements, enabling us to record voltage transients in unexpectedly large lateral distances away from the electrodes, can impact the understanding of various electrochemical concepts. © the Owner Societies 2016

Le juge administratif dans l'analyse juridique des politiques publiques

Aquesta ponència forma part del Workshop internacional de doctorands organitzat pel Programa de Doctorat en Dret de la UAB i la Facultat de Dret de la UAB, amb el suport de l'École Européenne de Droit de l'Université Toulouse Capitol