Small-signal harmonic analysis of non-linear circuits

An approximate harmonic analysis method for non-linear circuits is introduced. the method solves the steady state, time domain representation as well as the frequency response of non-linear circuits. It allows simulation of non-ideal switched capacitor circuits composed of any kinds of linear components and non-linear transistors as switches. All switches must have the same period, but they can be opened and closed at any time. the method proposed may also be applied to mixer analysis for the case of strong LO and weak RF signals. Examples are given to demonstrate that the method is efficient and sufficiently fast to be used in circuit design. the simulation results show good agreement with those obtained by harmonic balance and transient analysis.     

Fast estimation algorithm for likelihood-based analysis of repeated categorical responses

Likelihood-based marginal regression modelling for repeated, or otherwise clustered, categorical responses is computationally demanding. This is because the number of measures needed to describe the associations within a cluster increase geometrically with increasing cluster size. The proposed estimation methods typically describe the associations using odds ratios, which result in computationally unfeasible solutions for large cluster sizes. An alternative method for joint modelling of the regression, association, and dropout mechanism for clustered categorical responses is presented. The joint distribution of a multivariate categorical response is described by utilizing the mean parameterization, which facilitates maximum likelihood estimation in two important respects. The models are illustrated by analyses of the presence and absence of schizophrenia symptoms on 86 patients at 12 repeated time-points, and a survey of opinions of 607 adults regarding government spending on nine different targets, measured on a common 3-level ordinal scale. Free software is available.     

Magnitude and phase in thermal wave imaging

In thermal wave imaging on solids both magnitude and phase angle are used. However, a comparison between theoretical and experimental results is lacking even for the simple case of an air-backed metal plate. In the letter we present measurements and point out the difference between sinusoidal and square-wave intensity modulation.     

Duplex coating of electroless nickel and HVOF (high-velocity oxygen fuel) sprayed WC-Co

The porosity of thermal sprayed coatings is usually a problem when coatings are used in wet corrosion application. The porosity allows media to penetrate to the surface of the base material. Corrosion spreads rapidly and the coating loses contact with the substrate and delaminates. This problem can be initiated by impregnating different polymers into the pores. An alternative approach has been tested in the present work to prevent corrosion of cemented carbide coated carbon steel in wet corrosion environments. Carbon steel substrates were coated with a thin film of electroless nickel (electroless nickel plating) and then HVOF (High-Velocity Oxygen Fuel) sprayed with cemented carbide. Reference specimens without electroless nickel were sprayed at the same time. The microhardness of the specimens was measured and the coating structure examined using optical microscopy and X-ray diffractometry (XRD). The bond between the layers and the base material was examined by means of a bend test. A salt chamber test was also performed for the specimens. The structure of the electroless nickel layer was crystalline as a result of the HVOF spraying. There were no cracks in the nickel layer, if the layer was about 20 μm thick. According to the results of the bend test, the adhesion between coatings and substrate was good, and there was no difference between the duplex-coated specimen and the reference specimen. A sample with a thin nickel layer under an HVOF sprayed cemented carbide did not exhibit corrosion after 8 h in the salt chamber test.     

Value of measurement information: A simple case study on grade change decisions

Measurement systems produce information to support decision making. The added value of measurements is determined by how much the provided information improves decision making as uncertainty about decision consequences is reduced. We discuss through an example the value generation by measurement information in the context statistical decision theory (SDT). This example, a grade change decision, outlines the principle for determining added value in decision making. We discuss separately two value generation mechanisms: the direct value generation by reduced uncertainty on consequences and the indirect value generation through accumulating knowledge about the consequence model parameters. The first mechanism is solvable in analytic form and this allows comparing formulations of SDT in the analysis. We outline the analysis of the indirect value generation and show that even with this simple decision task the analysis is rather complex. We propose that the added-value analysis is the key to optimal design of measurement information systems.     

Engineered droplets for dried droplet solute deposition by mass spectrometric imaging

Solute deposition patterns of peptides are studied on dried droplet deposits from engineered droplet shapes using surface assisted laser desorption ionization mass spectrometric imaging. The engineered droplet shapes are achieved through superhydrophilic/hydrophobic patterned surfaces. Strong pinning of the contact line to the edges of the hydrophilic area causes the solutes to deposit mostly to the perimeter of the hydrophilic area on simple circular and square shaped spots. More complex geometries resulted in unique deposition patterns, showing potential for spotting and chemical analysis. In particular, a geometry where the analyte was split and concentrated onto eight discrete target sites is described. The deposition patterns of analyte mixtures are also studied, and spatial separation is observed between various analytes, enabling the possibility for analyte separation.     

Free-time habitation and layers of ecological history at a southern Finnish lake

I analyse ecological and cultural change as an intertwined, simultaneous process using a summer cottage habitation as a case. This habitation developed during the 20th century on the shores of Lake Roine, in southwestern Finland. My aim is to identify spatial and temporal scales constituted by the process, as well as its ecological influences in connection with socio-economic changes and ecohistorical layers of the area. The results indicate that the emergence of summer cottage culture is breaking the dichotomies between urban and rural and also merges different time horizons. Remarkable context dependence was found when the ecological influences were evaluated in relation to traditional peasant culture and modern silviculture. The present summer cottage occupants of the lake are often tightly engaged with their site by managing it and reusing artefacts innovatively. As managers they reflect both peasant and urban mentalities, and having great variation in management practices they create potentials for further changes in the ecosocial system.     

Citalopram in the treatment of obsessive-compulsive disorder: an open pilot study

PURPOSE: To evaluate QT dispersion in hypertensive patients, with and without left ventricular hypertrophy, and compare with normal persons. METHODS: Thirty eight patients (21 male and 17 female, age 55 +/- 15 years) underwent echocardiography and simultaneous 12 lead, vertically aligned, electrocardiogram at 50 mm/s speed. No patient was on antiarrhythmic therapy. There were 19 non-hypertensive patients that constituted the control group (G-I). Group II was constituted by the other 19 patients, who were hypertensives. This group was further divided in group II-A (9 patients without left ventricular hypertrophy) and group II-B (10 patients with left ventricular hypertrophy). QT dispersion was obtained by the difference between the longest and the shortest QT registered. RESULTS: QT dispersion was significantly increased on hypertensive patients, both with and without left ventricular hypertrophy, when compared to controls (G-I 31 +/- 9 ms, G-II 52 +/- 15 ms. P < 0.0001; G-IIa 46 +/- 10 ms and G-IIb 56 +/- 18 ms X G-I, p < 0.0005). In hypertensive patients, there was no statistically significant difference between group II-A and group II-B. CONCLUSION: We conclude that QT dispersion is significantly increased on hypertensive patients when compared to non-hypertensive individuals and that such increase, occurs before left ventricular hypertrophy develops. These findings suggest that, in hypertensive patients, electrical changes in left ventricular myocardium can precede structural and morphological abnormalities. Such findings offer new insights into the mechanisms related to enhanced mortality among hypertensive patients.