The Malm? model: a problem-based learning curriculum in undergraduate dental education

A new undergraduate dental curriculum was introduced in Malm? in 1990 which is based on problem-based learning (PBL). The principles of PBL are strongly influenced by evidence from cognitive psychology and they form the educational strategy throughout the whole curriculum. Two further essential principles underpin the curriculum: a holistic attitude to patient care, and the promotion of oral health. Basic sciences and clinical dentistry are integrated within a structure based on oral conditions prevalent in the community. Students are encouraged to build their new knowledge, understanding and skills into the context of what they have already learned. This approach is facilitated by the presentation of conceptual models, one of which, The Oral Ecosystem is described in detail. The educational programme also gives students opportunities to learn in the clinical context from an early stage, and we endeavour to promote a scientific attitude from the very beginning of the programme. This paper describes the curriculum at three organisational levels (whole curriculum, single course, individual week).     

Elements in rice from the Swedish market: 1. Cadmium, lead and arsenic (total and inorganic)

A survey of the levels of cadmium, lead and arsenic in different types of rice available on the Swedish retail market was carried out in 2001-03. The types of rice included long and short grain, brown, white, and parboiled white rice. The mean levels found were as follows: total As: 0.20 mg kg^-1, inorganic As: 0.11 mg kg^-1; Cd: 0.024 mg kg^-1; and Pb: 0.004 mg kg^-1. ICP-MS was used for the determination of As (total and inorganic) after acid digestion. Lead and cadmium were determined using graphite furnace atomic absorption spectrometry (GFAAS) after dry ashing. In countries where rice is a staple food, it may represent a significant contribution in relation to the provisional tolerable weekly intake for Cd and inorganic As.     

Pain analysis is vital in rheumatic diseases. Pain often causes much worry to patients

The article consists of a synthesis of a rheumatic pain symposium held at the annual meeting of the Swedish Medical Association in 1996. Various aspects of pain in rheumatic diseases were discussed, such as physiological, neurohumoral and neurogenic mechanisms, sensory stimulation treatment, differentiation of mechanical and inflammatory pain, quality enhancement by improved co-operation between primary and tertiary care facilities, pharmacological treatment with (centrally and peripherally acting) opioids, selective cyclo-oxygenase inhibitors, and NMDA (N-methyl-D-aspartate) receptor antagonists. For patients with rheumatic disorders exacerbated by pain problems, as for other patients, a pain diagnosis is of fundamental importance. This can be achieved by analysis of the social, psychological, physiological and medical factors contributing to the cause and degree of pain and to pain behaviour, and of the extent to which the pain may be nociceptive (i.e., inflammatory, mechanical, or ischaemic in origin), neurogenic or idiopathic. Pain analysis should be followed by individualised treatment focused on the patient's most crucial problems, thus enhancing the prospect of optimal treatment outcome.     

Benzene emitted from glowing charcoal

Benzene was assessed as the predominant aromatic compound emitted from glowing charcoal and firewood embers. Concentrations measured above charcoal used for grilling exceeded 10 mg m(-3) at a 5% carbon dioxide level. Charcoal with a high carbon content released less benzene. Glowing wood pellets emitted less benzene than glowing firewood remainders. The emissions of ethene and propene relative to benzene were low for commercial charcoal and wood-pellet embers, but high for firewood ember. The proportions of methylbenzene and naphthalene from charcoal were typically only 10% relative to benzene, and those of benzofuran, dibenzofuran and benzonitrile were typically below 5%. The polycyclic aromatic hydrocarbon (PAH) indicator phenanthrene was below the 1% level. Adsorbent sampling and GC-MS were used for assessing all the aromatic compounds. Earlier studies of charcoal emissions have focused on carbon monoxide, PAH and dioxins. It is concluded that the carcinogenic benzene may be an even more severe health hazard to be addressed by exposure-decreasing measures.     

Topology optimization of frame structures with flexible joints

A method for structural topology optimization of frame structures with flexible joints is presented. A typical frame structure is a set of beams and joints assembled to carry an applied load. The problem considered in this paper is to find the stiffest frame for a given mass. By introducing design variables for beams and joints, a mass distribution for optimal structural stiffness can be found. Each beam can have several design variables connected to its cross section. One of these is an area-type design variable which is used to represent the global size of the beam. The other design variables are of length ratio type, controlling the cross section of the beam. Joints are flexible elements connecting the beams in the structure. Each joint has stiffness properties and a mass. A framework for modelling these stiffnesses is presented and design variables for joints are introduced. We prove a theorem which can be interpreted as the fact that the removal of structural elements, e.g. joints or beams, can be modelled by a small strictly positive material amount assigned to the element. This is needed for the computations of sensitivities used in the applied gradient based iterative method. Both two and three dimensional problems, as well as multiple load cases and multiple mass constraints, are treated.     

Carrier medium exchange through ultrasonic particle switching in microfluidic channels

This paper describes a method, utilizing acoustic force manipulation of suspended particles, in which particles in a laminar flow microchannel are continuously translated from one medium to another with virtually no mixing of the two media. During the study, 5-microm polyamide spheres suspended in distilled water, spiked (contaminated) with Evans blue, were switched over to clean distilled water. More than 95% of the polyamide spheres could be collected in the clean medium while removing up to 95% of the contaminant. Preliminary experiments to use this method to wash blood were performed. Red blood cells were switched from blood, spiked with Evans blue, to clean blood plasma. At least 95% of the red blood cells (bovine blood) could be collected in clean blood plasma while up to 98% of the contaminant was removed. The obtained results indicate that the presented method can be used as a generic method for particle washing and, more specifically, be applied for both intraoperative and postoperative blood washing.     

Identification of Helicobacter in gastric biopsies by PCR based on 16S rDNA sequences: a matter of little significance for the prediction of H. pylori-associated gastritis?

The aim of the present study was to correlate molecular evidence of the presence of Helicobacter pylori in gastric biopsy samples, based on analysis of 16S rDNA, vacuolating toxin (vacA), urease A (ureA) and cagA genes, with the clinical, histological and serological findings in patients with H. pylori-associated gastritis. Fresh biopsy samples were collected from the gastric antrum and corpus of 22 asymptomatic volunteers with or without H. pylori-associated gastritis. Total DNA was extracted from the biopsy material and subjected to 16S rDNA PCR amplification, Southern blotting and 16S rDNA sequence analysis of the PCR products. The vacA, ureA and cagA genes were characterised by PCR amplification and Southern blot analysis. Based on partial 16S rDNA sequence analysis, DNA belonging to the genus Helicobacter was detected in gastric biopsy samples from 20 of 22 subjects, including seven of nine histologically and serologically normal controls. Six of 20 partial 16S rDNA sequences revealed variations within variable regions V3 and V4 that deviated from those of the H. pylori type strain ATCC 4350T and, therefore, possibly represented other species of Helicobacter. VacA genes identical with those of the type strain were found predominantly in the subjects with H. pylori gastritis, and all the patients except one were found to be cagA-positive. There was no evidence of false positive PCR reactions. In conclusion, the PCR-based molecular typing methods used here were apparently too sensitive when applied to the detection of H. pylori in human gastric tissues. The lack of quantitative analysis makes them inappropriate as clinical tools for the diagnosis of H. pylori-associated gastritis, despite the fact that they provide a qualitative and sensitive tool for the detection and characterisation of H. pylori in the gastrointestinal tract.     

Saturation capacitance of thin oxide MOS structures and the effective surface density of states of silicon

The capacitance vs voltage curve of thin oxide (30–40 Å) MOS structures in strong accumulation was studied. The results were interpreted in terms of equivalent surface density of state masses, which was found to be 0·2 m₀ for the silicon valence band and 0·06 m₀ for the conduction band, for both 111 and 100 surfaces. The experimental density of state masses were shown to be much lower than the bulk values. Equivalent density of states masses were calculated from a surface quantization model and in this case agreement with the experiments was obtained for the valence band only.     

Synthesis of a linear low‐density polyethylene/MgO@Mg(OH)2 nanocomposite using modified in situ polymerization

Composites of linear low‐density polyethylene were obtained in toluene slurry by in situ copolymerization of ethylene and 1‐octene in the presence of untreated magnesium oxide–hydroxide nanoparticles (MgO@Mg(OH)₂) of ±50 nm and such treated with dibutylmagnesium (DBM) as support for a bis(n‐butylcyclopentadienyl)zirconium dichloride–methylaluminoxane (MAO) catalyst system. Treatment of the nanoparticles with DBM (0.5–6 mmol g^?1 MgO@Mg(OH)₂) allows one to decrease the amount of MAO by 1.2 mmol Al g^?1 MgO@Mg(OH)₂, while reaching the same average catalyst activity and a finer distribution of the particles. Energy‐dispersive X‐ray mapping shows that the MAO is mainly associated with the filler. The crystallinity of the matrix polymer decreases with filler content. © 2018 Society of Chemical Industry