Four-point probe measurements using current probes with voltage feedback to measure electric potentials

We present a four-point probe resistance measurement technique which uses four equivalent current measuring units, resulting in minimal hardware requirements and corresponding sources of noise. Local sample potentials are measured by a software feedback loop which adjusts the corresponding tip voltage such that no current flows to the sample. The resulting tip voltage is then equivalent to the sample potential at the tip position. We implement this measurement method into a multi-tip scanning tunneling microscope setup such that potentials can also be measured in tunneling contact, allowing in principle truly non-invasive four-probe measurements. The resulting measurement capabilities are demonstrated for BiSbTe$_3$ and Si$(111)-(7\times7)$ samples

ICTs and the Adaptability of Woek Arrangements in the EU

ICT-enabled new ways of working are in general associated with increases in flexibility, and as such are central to the European Employment Strategy. This paper compares the progress individual EU Member States have made with regard to the diffusion of flexibility on labour markets. In order to do so, the authors set up an index model that is in line with the key policy objectives of the European Community, which means using a radically different approach as compared to existing labour market flexibility indices such as the one developed by the OECD. The AWAI (Adaptability of Work Arrangements Index) consists of two elements: one subindex measuring worker-centred flexibility and another one measuring company-centred flexibility. Using a preliminary selection of variables (which is based on a theoretical framework conceptualising the nature of developments in work organisation) for calculation of both of these components, the authors calculated AWAI scores for each of 10 EU Member States. Comparing the results for both sub-indices shows that there are marked differences between both rankings, with some countries performing well in one subindex and below-average in the other. The paper aims to contribute to the development of a more differentiated view at the issue of flexibility of labour markets

Oxygen vacancies in tungsten oxide and their influence on tungsten oxide silicon heterojunction solar cells

Tungsten oxide WOx can be incorporated into amorphous crystalline silicon heterojunction solar cells as hole contact and for interface modification between p type amorphous silicon and indium tin oxide. This paper aims at understanding the influence of tungsten oxides properties on silicon heterojunction solar cells. Using in system photoelectron spectroscopy on thermally evaporated WOx layers, it was verified that WOx with a stoichiometry close to WO3 features a work function close to 6 eV and is therefore suitable as hole contact on silicon. Additionally the oxygen vacancy concentration in WOx was measured using photoelectron spectroscopy. High oxygen vacancy concentrations in WOx lead to a low band bending in the WOx silicon junction. Furthermore solar cells were fabricated using the same WOx, and the band bending in these cells is correlated with their fill factors FF and open circuit voltages VOC VOC . Combining these results, the following picture arises positively charged oxygen vacancies raise the Fermi level in WOx and reduce the band bending at the WOx silicon junction. This, in turn, leads to reduced VOCVOC and FF. Thus, when incorporating WOx into silicon solar cells it is important to minimize the oxygen vacancy density in WOx. Therefore deposition methods, enabling adjustment of the WOx stoichiometry are preferabl

Etched graphene quantum dots on hexagonal boron nitride

We report on the fabrication and characterization of etched graphene quantum dots (QDs) on hexagonal boron nitride (hBN) and SiO2 with different island diameters. We perform a statistical analysis of Coulomb peak spacings over a wide energy range. For graphene QDs on hBN, the standard deviation of the normalized peak spacing distribution decreases with increasing QD diameter, whereas for QDs on SiO2 no diameter dependency is observed. In addition, QDs on hBN are more stable under the influence of perpendicular magnetic fields up to 9T. Both results indicate a substantially reduced substrate induced disorder potential in graphene QDs on hBN

Brief Cognitive Screening Tools for Primary Care Practice

Early detection and diagnosis of Alzheimer’s disease and other cognitive impairment presents as a critical issue facing primary and specialty care providers in Washington State. In order to address the gaps and challenges faced by providers, the Dementia Action Collaborative offers the current paper to provide information and guidance around early detection and diagnosis of memory loss and dementia, including Alzheimer’s disease. At the conclusion of this paper, providers should be able to identify indications and opportunities for detection, appropriate tools, and care pathways for individuals and families affected by cognitive impairment and dementia

Valence band alignment and hole transport in amorphous crystalline silicon heterojunction solar cells

To investigate the hole transport across amorphous crystalline silicon heterojunctions, solar cells with varying band offsets were fabricated using amorphous silicon suboxide films. The suboxides enable good passivation if covered by a doped amorphous silicon layer. Increasing valence band offsets yield rising hole transport barriers and reduced device effciencies. Carrier transport by thermal emission is reduced and tunnel hopping through valence band tail states increases for larger barriers. Nevertheless, stacks of films with different band gaps, forming a band offset staircase at the heterojunction could allow the application of these layers in silicon heterojunction solar cell

Socially defeated male rats display a blunted adrenocortical response to a low dose of 8-OH-DPAT

The study examined in male Wistar rats the influence of social defeat on the neuroendocrine stress response system using injection of the 5-HT1A receptor agonist, 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT), as the pharmacological challenge. Social defeat was defined by the submissive postures displayed by the Wistar rats which were threatened and attacked by Tryon Maze Dull S3 rats for 10 min. 18-20 h after social defeat, the defeated rats were injected intravenously (i.v.) with a low and high dose of 8-OH-DPAT in their home cages. Blood samples were withdrawn from the freely moving cannulated rats for determination of plasma corticosterone and catecholamines. The corticosterone response to the low dose of 8-OH-DPAT (0.05 mg/kg, i.v.) was significantly diminished in the defeated rats as compared to the controls, but this dose failed to affect catecholamine concentrations. The high dose of 8-OH-DPAT (0.15 mg/kg, i.v.) significantly elevated corticosterone and adrenaline levels in defeated and control rats to the same extent, whereas no effect on noradrenaline was found. The present data thus indicate that social defeat blunts 5-HT1A receptor-mediated adrenocortical activation probably via a decrease in the sensitivity of a population of postsynaptic 5-HT receptors

Electronic structure of indium tungsten oxide alloys and their energy band alignment at the heterojunction to crystalline silicon

The electronic structure of thermally co evaporated indium tungsten oxide films is investigated. The stoichiometry is varied from pure tungsten oxide to pure indium oxide and the band alignment at the indium tungsten oxide crystalline silicon heterointerface is monitored. Using in system photoelectron spectroscopy, optical spectroscopy and surface photovoltage measurements we show that the work function of indium tungsten oxide continuously decreases from 6.3 eV for tungsten oxide to 4.3 eV for indium oxide, with a concomitant decrease of the band bending at the hetero interface to crystalline silicon than indium oxid

Buyback Problem - Approximate matroid intersection with cancellation costs

In the buyback problem, an algorithm observes a sequence of bids and must decide whether to accept each bid at the moment it arrives, subject to some constraints on the set of accepted bids. Decisions to reject bids are irrevocable, whereas decisions to accept bids may be canceled at a cost that is a fixed fraction of the bid value. Previous to our work, deterministic and randomized algorithms were known when the constraint is a matroid constraint. We extend this and give a deterministic algorithm for the case when the constraint is an intersection of $k$ matroid constraints. We further prove a matching lower bound on the competitive ratio for this problem and extend our results to arbitrary downward closed set systems. This problem has applications to banner advertisement, semi-streaming, routing, load balancing and other problems where preemption or cancellation of previous allocations is allowed