Single-electron transistor made of two crossing multiwalled carbon nanotubes and its noise properties

A three-terminal nanotube device was fabricated from two multiwalled nanotubes by pushing one on top of the other using an atomic-force microscope. The lower nanotube, with gold contacts at both ends, acted as the central island of a single-electron transistor while the upper one functioned as a gate electrode. Coulomb blockade oscillations were observed on the nanotube at sub-Kelvin temperatures. The voltage noise of the nanotube single-electron transistor (SET) was gain dependent as in conventional SETs. The charge sensitivity at 10 Hz was 6×10 exp −4  e/√Hz.Peer reviewe

Multiwalled carbon nanotubes as ultrasensitive electrometers

We show that it is possible to construct low-noise single-electron transistors (SETs) using free-standing multiwalled carbon nanotubes. The 1/fα -noise of our devices, 6×10 exp −6 e/√Hz at 45 Hz, is close in the performance to the best metallic SETs of today.Peer reviewe

Multiwalled carbon nanotube: Luttinger liquid or not?

We have measured IV-curves of multiwalled carbon nanotubes using end contacts. At low voltages, the tunneling conductance obeys non-Ohmic power law, which is predicted both by the Luttinger liquid and the environment-quantum-fluctuation theories. However, at higher voltages we observe a crossover to Ohm's law with a Coulomb-blockade offset, which agrees with the environment-quantum-fluctuation theory, but cannot be explained by the Luttinger-liquid theory. From the high-voltage tunneling conductance we determine the transmission line parameters of the nanotubes.Comment: RevTeX, 4 pages, 2 EPS-figures, submitted to Phys. Rev. Let

The association between neighborhood characteristics and mental health in old age – register based study of urban areas in three European countries

This study aimed to fill the gap in research regarding the longitudinal studies on the association between urban neighborhood characteristics and mental health of older populations. Individual level register-based data sets from Finland (10 largest cities), Sweden (Stockholm), and Italy (Turin) including satellite based land cover data were used. The data included sociodemographic individual information on population aged 50+, their antidepressant purchases, and socioeconomic and physical characteristics regarding area of residence. We followed individuals for antidepressant purchases for 5 years in 2001-2015, depending on dataset, and used hierarchical negative binomial models to assess whether there was an association between social and physical area characteristics and antidepressant use and to what extent was this association attributable to individual sociodemographic characteristics of the residents and whether the findings were consistent across countries. We found weak and inconsistent evidence of high levels of area characteristics related to dense physical urban structure being predictive of increased antidepressant use in ages above 50. However, generally the extent to which antidepressant use was clustered by areas in the studied contexts was minimal

Trends in mortality by labour market position around retirement ages in three European countries with different welfare regimes

<p>Objectives: In the face of economic downturn and increasing life expectancy, many industrial nations are adopting a policy of postponing the retirement age. However, questions still remain around the consequence of working longer into old age. We examine mortality by work status around retirement ages in countries with different welfare regimes; Finland (social democratic), Turin (Italy; conservative), and England and Wales (liberal).</p> <p>Methods: Death rates and rate ratios (RRs) (reference rates = ‘in-work’), 1970 s–2000 s, were estimated for those aged 45–64 years using the England and Wales longitudinal study, Turin longitudinal study, and the Finnish linked register study.</p> <p>Results: Mortality of the not-in-work was consistently higher than the in-work. Death rates for the not-in-work were lowest in Turin and highest in Finland. Rate ratios were smallest in Turin (RR men 1972–76 1.73; 2002–06 1.63; women 1.22; 1.68) and largest in Finland (RR men 1991–95 3.03; 2001–05 3.80; women 3.62; 4.11). Unlike RRs for men, RRs for women increased in every country (greatest in Finland).</p> <p>Conclusions: These findings signal that overall, employment in later life is associated with lower mortality, regardless of welfare regime.</p&gt

The Nature of Abstract Orthographic Codes: Evidence from Masked Priming and Magnetoencephalography

What kind of mental objects are letters? Research on letter perception has mainly focussed on the visual properties of letters, showing that orthographic representations are abstract and size/shape invariant. But given that letters are, by definition, mappings between symbols and sounds, what is the role of sound in orthographic representation? We present two experiments suggesting that letters are fundamentally sound-based representations. To examine the role of sound in orthographic representation, we took advantage of the multiple scripts of Japanese. We show two types of evidence that if a Japanese word is presented in a script it never appears in, this presentation immediately activates the (“actual”) visual word form of that lexical item. First, equal amounts of masked repetition priming are observed for full repetition and when the prime appears in an atypical script. Second, visual word form frequency affects neuromagnetic measures already at 100–130 ms whether the word is presented in its conventional script or in a script it never otherwise appears in. This suggests that Japanese orthographic codes are not only shape-invariant, but also script invariant. The finding that two characters belonging to different writing systems can activate the same form representation suggests that sound identity is what determines orthographic identity: as long as two symbols express the same sound, our minds represent them as part of the same character/letter

Associations between PM2.5 and Heart Rate Variability Are Modified by Particle Composition and Beta-Blocker Use in Patients with Coronary Heart Disease

BACKGROUND: It has been hypothesized that ambient particulate air pollution is able to modify the autonomic nervous control of the heart, measured as heart rate variability (HRV). Previously we reported heterogeneous associations between particulate matter with aerodynamic diameter < 2.5 mu m (PM2.5) and HRV across three study centers. OBJECTIVE: We evaluated whether exposure misclassification, effect modification by medication, or differences in particle composition could explain die inconsistencies. METHODS: Subjects with coronary heart disease visited clinics biweekly in Amsterdam, the Netherlands; Erfurt, Germany; and Helsinki, Finland for 6-8 months. The standard deviation (SD) of NN intervals on an electrocardiogram (ECG; SDNN) and high frequency (HF) power of HRV was measured with ambulatory ECG during paced breathing. Outdoor levels of PM2.5 were measured at a central site. In Amsterdam and Helsinki, indoor and personal PM2.5 were measured during the 24 hr preceding the clinic visit. PM2.5 was apportioned between sources using principal component analyses. We analyzed associations of indoor/personal PM2.5 elements of PM2.5 and source-specific PM2.5 With HRV using linear regression. RESULTS: Indoor and personal PM2.5 were not associated with HRV. Increased outdoor PM2.5 was associated with decreased SDNN and HF at lags of 2 and 3 days only among persons not using beta-blocker medication. Traffic-related PM2.5 was associated with decreased SDNN, and long-range transported PM2.5 with decreased SDNN and HF, most strongly among persons not using beta blockers. Indicators for PM2.5 from traffic and long-range transport were also associated with decreased HRV. CONCLUSIONS: Our results suggest that differences in the composition of particles, beta-blocker use, and obesity of study subjects may explain some inconsistencies among previous studies on HRV

Association between neighbourhood characteristics and antidepressant use at older ages: A register-based study of urban areas in three European countries

Background: Research evidence on the association between neighbourhood characteristics and individual mental health at older ages is inconsistent, possibly due to heterogeneity in the measurement of mental-health outcomes, neighbourhood characteristics and confounders. Register-based data enabled us to avoid these problems in this longitudinal study on the associations between socioeconomic and physical neighbourhood characteristics and individual antidepressant use in three national contexts. Methods: We used register-based longitudinal data on the population aged 50+ from Turin (Italy), Stockholm (Sweden), and the nine largest cities in Finland linked to satellite-based land-cover data. This included individual-level information on sociodemographic factors and antidepressant use, and on neighbourhood soci

Activation of the Left Inferior Frontal Gyrus in the First 200 ms of Reading: Evidence from Magnetoencephalography (MEG)

BACKGROUND: It is well established that the left inferior frontal gyrus plays a key role in the cerebral cortical network that supports reading and visual word recognition. Less clear is when in time this contribution begins. We used magnetoencephalography (MEG), which has both good spatial and excellent temporal resolution, to address this question. METHODOLOGY/PRINCIPAL FINDINGS: MEG data were recorded during a passive viewing paradigm, chosen to emphasize the stimulus-driven component of the cortical response, in which right-handed participants were presented words, consonant strings, and unfamiliar faces to central vision. Time-frequency analyses showed a left-lateralized inferior frontal gyrus (pars opercularis) response to words between 100-250 ms in the beta frequency band that was significantly stronger than the response to consonant strings or faces. The left inferior frontal gyrus response to words peaked at approximately 130 ms. This response was significantly later in time than the left middle occipital gyrus, which peaked at approximately 115 ms, but not significantly different from the peak response in the left mid fusiform gyrus, which peaked at approximately 140 ms, at a location coincident with the fMRI-defined visual word form area (VWFA). Significant responses were also detected to words in other parts of the reading network, including the anterior middle temporal gyrus, the left posterior middle temporal gyrus, the angular and supramarginal gyri, and the left superior temporal gyrus. CONCLUSIONS/SIGNIFICANCE: These findings suggest very early interactions between the vision and language domains during visual word recognition, with speech motor areas being activated at the same time as the orthographic word-form is being resolved within the fusiform gyrus. This challenges the conventional view of a temporally serial processing sequence for visual word recognition in which letter forms are initially decoded, interact with their phonological and semantic representations, and only then gain access to a speech code