High-mobility solution-processed copper phthalocyanine-based organic field-effect transistors

© 2011 National Institute for Materials ScienceSolution-processed films of 1,4,8,11,15,18,22,25-octakis(hexyl) copper phthalocyanine (CuPc6) were utilized as an active semiconducting layer in the fabrication of organic field-effect transistors (OFETs) in the bottom-gate configurations using chemical vapour deposited silicon dioxide (SiO2) as gate dielectrics. The surface treatment of the gate dielectric with a self-assembled monolayer of octadecyltrichlorosilane (OTS) resulted in values of 4×10−2 cm2 V−1 s−1 and 106 for saturation mobility and on/off current ratio, respectively. This improvement was accompanied by a shift in the threshold voltage from 3V for untreated devices to −2V for OTS treated devices. The trap density at the interface between the gate dielectric and semiconductor decreased by about one order of magnitude after the surface treatment. The transistors with the OTS treated gate dielectrics were more stable over a 30-day period in air than untreated ones.Technology Strategy Board, UK (Project No: TP/6/EPH/6/S/K2536J)

Strategy and Choice in the 1988 Presidential Primaries

In recent years, thinking about the American Presidential primaries has been dominated by the image of Carter's victory in 1976. Conventional wisdom in the eighties has advised Presidential candidates to focus on the early contests in Iowa and New Hampshire, and to at least match, or better yet, exceed the expectations that the press, pollsters, and pundits have for them in those states. The successful campaign, it was thought, had to force the competition out by the end of March in order to lock up the nomination before the convention. This common wisdom - the so-called "momentum theory" - will now have to be revised as a result of what happened in the 1988 primaries. While one candidate from each patty did eventually emerge victorious in 1988, no one followed the Carter script as closely as expected. The Democratic race was not clearly resolved until Dukakis managed consecutive victories over Jackson in Wisconsin (April 5), New York (April 19) and Pennsylvania (April 26). On the Republican side, even though the race was over after Super Tuesday, the conventional "momentum" story was still marred by the odd-and in the end, meaningless-­outcome in Iowa Republican caucuses. Bush exceeded expectations in Iowa, but in a negative direction, and both Dole and Robertson were unable to convert their successes into any advantage in New Hampshire and the South. In this paper, we use data from a series of 12 exit polls conducted by the Los Angeles Times to explain the course of the 1988 Democratic and Republican presidential primary campaigns. The Los Angeles Times sample of primaries includes the critical early Democratic and Republican contests in Iowa and New Hampshire, six Super Tuesday states, and the Democratic primaries in Illinois, New York, Pennsylvania and California. The story we tell is quite simple. Momentum in both races was slowed by regionalism, and in the Democratic contest specifically, by the non-strategic support that blacks and affluent liberal whites gave Jesse Jackson. Momentum accelerated in the New York and Pennsylvania primaries as moderate and Jewish voters strategically switched to Dukakis in order to block Jesse Jackson's nomination. Both Bush and Dukakis staked out positions for themselves near the center of the ideological spectrum in their respective parties. As it turned out, the distribution of voter preferences, combined with strategic complications typical of multicandidate races, served to make the middle an advantageous spot for the victorious candidates

Markov semigroups, monoids, and groups

A group is Markov if it admits a prefix-closed regular language of unique representatives with respect to some generating set, and strongly Markov if it admits such a language of unique minimal-length representatives over every generating set. This paper considers the natural generalizations of these concepts to semigroups and monoids. Two distinct potential generalizations to monoids are shown to be equivalent. Various interesting examples are presented, including an example of a non-Markov monoid that nevertheless admits a regular language of unique representatives over any generating set. It is shown that all finitely generated commutative semigroups are strongly Markov, but that finitely generated subsemigroups of virtually abelian or polycyclic groups need not be. Potential connections with word-hyperbolic semigroups are investigated. A study is made of the interaction of the classes of Markov and strongly Markov semigroups with direct products, free products, and finite-index subsemigroups and extensions. Several questions are posed.Comment: 40 pages; 3 figure

APOE ε4, Alzheimer's disease neuropathology, and sleep disturbance, in individuals with and without dementia

BACKGROUND: Apolipoprotein E epsilon 4 (APOE-ε4) carrier status is an established risk factor for Alzheimer’s disease (AD) dementia. It has also been linked with sleep disturbance in healthy older adults and increased insomnia risk. This association may be driven by the effect of APOE-ε4 on AD pathological change, itself associated with sleep abnormalities. To assess this relationship, we have evaluated post-mortem neuropathological findings in patients with and without cognitive impairment and AD pathology, who had extensive clinical assessment within 12 months of death. METHODS: This retrospective cohort study used UK Brain Banks Network data. Eligible subjects were aged over 50, with pre-mortem neuropsychiatry inventory scores of sleep disturbance (NPI-K), neurocognitive testing and functional cognitive status assessment (Clinical Dementia Rating scale). Neuropathological data included Thal phase, Braak stage and CERAD scores (measures of Aβ plaque distribution, tangle distribution and neuritic plaque density, respectively) combined to form the National Institute on Aging Alzheimer’s Association (NIA-AA) ABC score reflecting AD neuropathology. Participants with other significant intracerebral pathology or pathological features of non-AD dementia were excluded. Multivariate linear regression was performed with NPIK Global Score (NPIK frequency score multiplied by severity score) as the dependent variable and APOE-ε4 heterozygosity or homozygosity as independent variables. Covariates included age, gender, APOE-ε2 status and ABC NPI measures reflecting depression and anxiety. Further models stratified by ABC score and functional cognitive status were also produced. RESULTS: Seven hundred twenty-eight records were identified. Two hundred two participants were included in the final analysis: mean (SD) age 84.0 (9.2) and MMSE 14.0 (11.8). Mean sleep disturbance scores were highest in ε4 homozygosity (n=11), 4.55 (5.4); intermediate in ε4 heterozygosity (n=95), 2.03 (4.0); and lowest in non-ε4 carriers (n=96), 1.36 (3.3). Within the full sample, controlling for pathological status, age, gender, depression, anxiety and CDR-SOB status, APOE-ε4 homozygosity was associated with sleep disturbance (β 2.53, p=0.034). APOE-ε4 heterozygosity was similarly associated in individuals without dementia (β 1.21, p=0.048). CONCLUSION: These findings lend weight to the hypothesis that APOE-ε4 affects sleep by mechanisms independent of AD pathological change. Evaluation of those mechanisms would enhance understanding of sleep disturbance pathways and potentially provide treatment targets. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13195-022-00992-y

On the informational content of wage offers

This article investigates signaling and screening roles of wage offers in a single-play matching model with two-sided unobservable characteristics. It generates the following predictions as matching equilibrium outcomes: (i) “good” jobs offer premia if “high-quality” worker population is large; (ii) “bad” jobs pay compensating differentials if the proportion of “good” jobs to “low-quality” workers is large; (iii) all firms may offer a pooling wage in markets dominated by “high-quality” workers and firms; or (iv) Gresham’s Law prevails: “good” types withdraw if “bad” types dominate the population. The screening/signaling motive thus has the potential of explaining a variety of wage patterns

Perception of soundscapes : an interdisciplinary approach

This paper takes an overall view of findings from the Positive Soundscape Project, a large inter-disciplinary soundscapes study. Qualitative fieldwork (soundwalks and focus groups) have found that soundscape perception is influenced by cognitive effects such as the meaning of a soundscape and its components, and how information is conveyed by a soundscape, for example on the behaviour of people within the soundscape. Three significant clusters were found in the language people use to describe soundscapes: sound sources, sound descriptors and soundscape descriptors. Results from listening tests and soundwalks have been integrated to show that the two principal dimensions of soundscape emotional response seem to be calmness and vibrancy. Further, vibrancy seems to have two aspects: organisation of sounds and changes over time. The possible application of the results to soundscape assessment and design are briefly discussed

A characterization of those automata that structurally generate finite groups

Antonenko and Russyev independently have shown that any Mealy automaton with no cycles with exit--that is, where every cycle in the underlying directed graph is a sink component--generates a fi- nite (semi)group, regardless of the choice of the production functions. Antonenko has proved that this constitutes a characterization in the non-invertible case and asked for the invertible case, which is proved in this paper

Biomarkers of Heavy Metal Effects in Two Species of Caddisfly Larvae from Clark Fork River, Montana: Stress Proteins (HSP70) and Lysosomal Membrane Integrity

Potential sublethal effects of heavy metals in stream macroinvertebrates were examined with two cellular and biochemical biomarkers in larvae of two caddisflies indigenous to the Clark Fork River, Montana, - Hydropsyche spp. and Arctopsyche grandis. Stress proteins, in particular members of the HSP70 family, are involved in cellular protein homeostasis and repair, and are induced by a variety of stressors, which either damage cellular proteins directly or cause cells to synthesize aberrant proteins. Lysosomes are intracellular organelles that play key roles in the detoxification of both organic and inorganic xenobiotic compounds. Larvae of Hydropsyche spp. were collected from four sites on the Clark Fork (Galen Gage--4.7 km, Goldcreek--85.6 km, Turah--189.7 km, above Flathead--381 km) and a reference site (the Blackfoot River). Larvae of A. grandis were collected from the same sites minus the Galen site. Samples were immediately frozen in liquid nitrogen for HSP70 analysis, or preserved with Tissue Tek, then frozen in liquid nitrogen for the lysosomal stability assay. HSP70 was analyzed by western blotting using monoclonal antibodies. Lysosomal integrity was measured in cryosections by acid labilization with acid phosphatase as a marker enzyme. Results to date show elevated tissue concentrations of Cd, Cu, Pb and Zn and significantly increased levels of HSP70 in Arctopsyche from Goldcreek compared to reference samples. Lysosomal integrity also was compromised in samples from Goldcreek. In Hydropsyche, tissue concentrations of Cd, Cu and Pb from Galen Gage were elevated (4-7 times) relative to the Blackfoot River, but levels of HSP70 did not differ between the two sites. These preliminary results indicate that sublethal effects of metal exposure may differ between species

Renormalization group approach to energy level statistics at the integer quantum Hall transition

We extend the real-space renormalization group (RG) approach to the study of the energy level statistics at the integer quantum Hall (QH) transition. Previously it was demonstrated that the RG approach reproduces the critical distribution of the {\em power} transmission coefficients, i.e., two-terminal conductances, $P_{\text c}(G)$, with very high accuracy. The RG flow of $P(G)$ at energies away from the transition yielded the value of the critical exponent, $\nu$, that agreed with most accurate large-size lattice simulations. To obtain the information about the level statistics from the RG approach, we analyze the evolution of the distribution of {\em phases} of the {\em amplitude} transmission coefficient upon a step of the RG transformation. From the fixed point of this transformation we extract the critical level spacing distribution (LSD). This distribution is close, but distinctively different from the earlier large-scale simulations. We find that away from the transition the LSD crosses over towards the Poisson distribution. Studying the change of the LSD around the QH transition, we check that it indeed obeys scaling behavior. This enables us to use the alternative approach to extracting the critical exponent, based on the LSD, and to find $\nu=2.37\pm0.02$ very close to the value established in the literature. This provides additional evidence for the surprising fact that a small RG unit, containing only five nodes, accurately captures most of the correlations responsible for the localization-delocalization transition.Comment: 10 pages, 11 figure

On Bootstrap Percolation in Living Neural Networks

Recent experimental studies of living neural networks reveal that their global activation induced by electrical stimulation can be explained using the concept of bootstrap percolation on a directed random network. The experiment consists in activating externally an initial random fraction of the neurons and observe the process of firing until its equilibrium. The final portion of neurons that are active depends in a non linear way on the initial fraction. The main result of this paper is a theorem which enables us to find the asymptotic of final proportion of the fired neurons in the case of random directed graphs with given node degrees as the model for interacting network. This gives a rigorous mathematical proof of a phenomena observed by physicists in neural networks