Ion etching of ultranarrow structures

We describe the use of Polymethylmethacrylate as both electron beam sensitive resist and ion etch mask for high-resolution pattern transfer. By using high-resolution electron beam lithography, chemically assisted ion beam etching, and in-situ metallization, we have fabricated ultra-narrow gates with lateral dimensions below 20 nm, spaced with < 50 nm pitch on high mobility 2D electron gas material. This technique, which is thought to provide extremely small lateral electron depletion lengths and well defined confienement potentials, allows us to produce new and more complicated structures for the study of quantum transport

Richtlijn schizofrenie 2012: basiszorg op het gebied van psychosociale interventies en verpleegkundige zorg.

Background An updated version of the Dutch multidisdplinaiy guideline on schizophrenia was published in 2012. aim We aim to provide an overview of the psychosocial interventions and nursing care which, according to the guideline, should be included in basic care programmes for patients with schizophrenia. We consider which interventions are effective and which are optional. In addition, we argue for continuous updating of the guideline so that it rejlects current developments. method We conducted a systematic review on the basis of specific predefined search terms. We included articles published up to February 2010. We used the methodfor evidence-based guideline development in order to formulate treatment recommendations. conclusion Cognitive behavioural therapy and Jamily interventions are scientifically proven interventions that should be included in the care programmes. Although there is no clear evidence that psycho-education is effective, it is nevertheless recommended. Optional interventions are peer support groups and, in the case of negative symptoms, psychomotor therapy. Although scientific evidence concerning nursing care is limited, we do make some recommendations. We are strongly in/avour of a 'living guideline' that is constantly developed and updated

Microfabrication below 10 nm

We describe a new electron beam lithography method for producing structures with lateral sizes smaller than the incident beam diameter. These patterns are transferred into GaAs/AlGaAs, InGaAs/GaAs and InGaAs/InP quantum well heterostructures using chemically assisted ion beam etching, thereby forming uniform arrays of pillars with lateral dimensions at or below 10 nm. To correlate the sizes of such structures with our exposure and development conditions, reflection electron microscopy observations are used

Imaging dielectric relaxation in nanostructured polymers by frequency modulation electrostatic force microscopy

We have developed a method for imaging the temperature-frequency dependence of the dynamics of nanostructured polymer films with spatial resolution. This method provides images with dielectric compositional contrast well decoupled from topography. Using frequency-modulation electrostatic-force-microscopy, we probe the local frequency-dependent (0.1–100 Hz) dielectric response through measurement of the amplitude and phase of the force gradient in response to an oscillating applied electric field. When the phase is imaged at fixed frequency, it reveals the spatial variation in dielectric losses, i.e., the spatial variation in molecular/dipolar dynamics, with 40 nm lateral resolution. This is demonstrated by using as a model system; a phase separated polystyrene/polyvinyl-acetate (PVAc) blend. We show that nanoscale dynamic domains of PVAc are clearly identifiable in phase images as those which light-up in a band of temperature, reflecting the variations in the molecular/dipolar dynamics approaching the glass transition temperature of PVAc

Direct measurement of the transmission matrix of a mesoscopic conductor

We have developed an experimental approach which permits evaluation of the entire transmission matrix of a mesoscopic conductor. Results are presented from two new investigations enabled by this technique: (a) We study ballistic multiprobe conductors in the limit of weak probe coupling, and (b) we image modal features in the distribution function of electrons emerging from a quantum point contact

Ion etching of ultranarrow structures

We describe the use of Polymethylmethacrylate as both electron beam sensitive resist and ion etch mask for high-resolution pattern transfer. By using high-resolution electron beam lithography, chemically assisted ion beam etching, and in-situ metallization, we have fabricated ultra-narrow gates with lateral dimensions below 20 nm, spaced with < 50 nm pitch on high mobility 2D electron gas material. This technique, which is thought to provide extremely small lateral electron depletion lengths and well defined confienement potentials, allows us to produce new and more complicated structures for the study of quantum transport

Epidemiological and economic effects of Salmonella control in the pork supply chain

In this paper a salmonella simulation model for the pork production chain is presented to evaluate the epidemiological and economic effects of hygiene measures and price differentiation on Salmonella. Results indicate that the farm stages in the chain are the most important stages to achieve reduction of Salmonella in pork. To reach an acceptable overall level of Salmonella however, every stage has to contribute. With a new system of price differentiation between infected and Salmonella free piglets and pork, the stages can be motivated to take measures for reduction and control of Salmonella

Are transport anomalies in "electron waveguides" classical?

We test the implicit prediction of a recent classical model that transport anomalies in ballistic multiprobe conductors—the last plateau, quenching, and the negative bend resistance—should scale with Fermi momentum, pF. Data from junctions defined by adiabatic lateral potentials (having corners with radii of curvature rJ>ħ/pF) qualitatively scale classically; departures observed are attributed to momentum-memory loss from random scattering. With more abrupt (square-cornered) junctions, however, nonclassical pF dependence emerges

Experimental measurement of scattering coefficients in mesoscopic conductors

We describe a general experimental approach yielding the entire transmission matrix of a multiprobe mesoscopic conductor. Results are presented for several new investigations with ballistic semiconductor nanostructures enabled by this technique. We measure the transmission coefficients for an open cross junction employing a sample design which is an almost literal realization of the Landauer-Büttiker model and verify that these transmission coefficients are consistent with Hall and bend resistance anomalies obtained by resistance measurements at low magnetic fields. Other investigations utilize a pinched cross junction in which two of the probes are separated from the channel by quantum point contacts. This series arrangement of point contacts allows a sensitive momentum spectroscopy of the emitted distribution. Even in the case of a single propagating mode, through the constrictions we observe modal features in the outgoing distribution. This indicates that the potential is spatially nonadiabatic even though conductance quantization is observed. This pinched geometry also allows the first fully characterized realization of weakly coupled probes

Sensory processing deficiencies in patients with borderline personality disorder who experience auditory verbal hallucinations

Auditory verbal hallucinations (AVH) are common in patients with borderline personality disorder (BPD). We examined two candidate mechanisms of AVH in patients with BPD, suggested to underlie sensory processing systems that contribute to psychotic symptoms in patients with schizophrenia; sensory gating (P50 ratio and P50 difference) and change detection (mismatch negativity; MMN). Via electroencephalographic recordings P50 amplitude, P50 ratio, P50 difference and MMN amplitude were compared between 23 borderline patients with and 25 without AVH, and 26 healthy controls. Borderline patients with AVH had a significantly lower P50 difference compared with healthy controls, whereas no difference was found between borderline patients without AVH and healthy controls. The groups did not differ on MMN amplitude. The impaired sensory gating in patients with borderline personality disorder who experience AVH implies that P50 sensory gating deficiencies may underlie psychotic vulnerability in this specific patient group. Patients with borderline personality disorder with or without AVH did not have problems with auditory change detection. This may explain why they are spared from the poor outcome associated with negative symptoms and symptoms of disorganization in patients with chronic schizophrenia