Detection of smoke gases by solid state sensors — A focus on research activities

Conventional smoke detection in fire alarm systems is based on a measurement of either physical properties of smoke aerosols (ionization and optical detectors), temperature increase (thermal detectors) or electromagnetic radiation emitted by the fire (radiation detectors). Not much emphasis has been put on smoke gases as signatures of various types of fires. In this paper the most elementary gases produced in CEN-norm fires are qualitatively discussed in order to define levels of gas concentrations reached on time scales typical of early fire warning. Based on that information, various principles and the current state of the research and development of solid state gas sensors are presented and discussed. These are, in particular, the solid state electrolyte, the metal oxide semiconductor, the silicon semiconductor device element and, finally, the microcalorimeter. It is concluded that, with the exception of the last mentioned operating principle, solid state gas detection could provide a viable alternative or additional means for the detection of smouldering or pyrolytic fires at an early stage.     

Letrozole, a new oral non-steroidal aromastase inhibitor in treating postmenopausal patients with advanced breast cancer. A pilot study

Chromosome analysis was performed in 160 patients with cryptorchidism. Chromosomal anomalies were found in 7 patients (4.4%). The incidence of chromosomal abnormalities was not significantly different between patients with bilateral or unilateral cryptorchidism. Of 7 patients, 1 had sex chromosomal aberration, 2 had marker chromosome and 4 had autosomal anomalies. Additional congenital anomalies were observed in 1 with sex chromosomal aberration, 2 with marker chromosome and 2 with autosomal anomaly. These facts indicate that we had better perform chromosome analysis in all patients with bilateral or unilateral cryptorchidism.     

Frictional contact of flexible and rigid bodies

 This paper is about planar frictional contact problems of both flexible and rigid bodies. For the flexible case a nonlinear finite element formulation is presented, which is based on a modified Coulomb friction law. Stick-slip motion is incorporated into the formulation through a radial return mapping scheme. Linearly interpolating four node elements and three node contact elements are utilized for the finite element discretization. The corresponding tangent stiffness matrices and residual vectors of the equations of motion are presented. In the rigid body case the contact problem is divided into impact and continual contact, which are mathematically described by linear complementarity problems. The impact in normal direction is modeled by a modified Poisson hypothesis, which is adapted to allow multiple impacts. The formulation of the tangential impact is grounded on Coulombs law of friction. The normal contact forces of the continual contact are such that colliding bodies are prevented from penetration and the corresponding tangential forces are expressed by Coulombs law of friction. Examples and comparisions between the different methods are presented. Received: 10 January 2001     

Composition-microstructure-property relationships in ceramic monofilaments resulting from the pyrolysis of a polycarbosilane precursor at 800 to 400 °C

A 15 m monofilament was extruded from a Yajima's type molten polycarbosilane, stabilized by addition of oxygen and heat-treated at 800 to 1400 °C under an argon atmosphere. Two important phenomena occur during pyrolysis. At 500 to 750 °C, an organic-inorganic state transition takes place with a first weight loss. It yields an amorphous material stable up to about 1100 °C. At this temperature, its composition is close to Si₄C₅O₂. It can be described as a continuum of SiC₄ and/or SiC_4–x O_x tetrahedral species (and possibly contains free carbon), with a homogeneity domain size less than 1 nm. The amorphous filament exhibits a high strength and semi-conducting properties. Above 1200 °C, a thermal decomposition of the amorphous material takes place with an evolution of gaseous species thought to be mainly SiO and CO, an important cross-section shrinkage and the formation of 7 to 20 nm SiC crystals which are surrounded with a poorly organized turbostratic carbon. The amorphous-crystalline state transition results in a drop in the tensile failure strength and an increase, by four orders of magnitude, in the electrical conductivity which becomes temperature independent. The former effect is due to the crystallization of the filament and the latter to a percolation phenomenon related to the intergranular carbon. The low stiffness is also due to the presence of carbon. It is anticipated that this transition is mainly related to the decomposition of the silicon oxycarbide species. Finally, a 40 to 50 nm layer of turbostratic carbon is formed at the filament surface at 1200 to 1400 °C whose origin remains uncertain. It is thought to be mainly responsible for the formation of the carbon interphase in the high-temperature processing of ceramic matrix composites.     

Use of spectral analysis in the detection of frequency differencesin the electrogastrograms of normal and diabetic subjects

The authors investigated the basal electrical rhythm (BER) of the stomach to determine if abnormalities of the BER occur in association with those gastric complaints in patients with long-term insulin-dependent diabetes. They recorded the basal electrical signal of the stomach in nine patients with diabetic gastroparesis and in 11 normal volunteers. They developed a microcomputer-based running spectral analysis technique (overlapping fast Fourier transforms) to analyze the recordings. They found no significant differences between the two subject groups in the prefed state but found a significantly higher proportion of episodes of high frequency, or tachygastria in the diabetic group in the postfed state (15.4-6.2%). The difference was also reflected in the higher postfed mean `peak' frequency of the diabetics. Both diabetics and normals show an increase in the mean of the peak frequency from pre- to postfed states, but the normals do not show an increase in episodes of tachygastria     

A dynamical formalism for unrooted systems of rigid bodies

Summary This paper presents a general formalism for the dynamics ofunrooted systems (=systems without kinematical coupling to a Galilean frame). Starting point are Lagrange's equations in ordered form. A set of points, themain points — introduced by O. Fischer hundred years ago- and a fictious body, theaugmented generalized body, permit to separate the translation of the mass center from the motion in the other coordinates. The basic idea is to break up the virtual velocity of a particle into component velocities that can be readily expressed in algebraic form. This allows, after some tensor-algebraic manipulations, an elegant representation ofall inertia coefficents as a linear function ofone kind of tensor, namely thebasic kinetic tensor. Newglobal inertia tensors (GITs), a generalization of those introduced by M. Fayet, are defined. They allow to separate geometry from affine geometry. GITs of order zero are shown to be ageneralization of the reduced mass. A recursive method is presented for efficent formulation of GITs of order one and two. It is also briefly indicated how rooted systems can be interpreted as a special case of rooted ones. A new formula to compute generalized forces due to a nonhomogeneous Newtonian force field is proposed. Results for rooted trees are reviewed as far as they are necessary for the purposes of this paper. The whole method translates conveniently into efficent computer codes.     

Prevalence of antibodies against virus-like particles of Epidermodysplasia verruciformis-associated HPV8 in patients at risk of skin cancer

The dietary intake of saturated fatty acids affects arteriosclerosis. We studied the effect of supplementation (15% wt/wt) of a hyperlipemic diet (1.3% cholesterol) with evening primrose oil (Oenothera biennis) in four groups of 10 rabbits each. After 6 weeks the aortic endothelium was analyzed morphologically with scanning electron microscopy, and the arterial wall was studied with morphometric techniques and cell nucleus counts. Endothelial functioning was analyzed by measuring prostacyclin synthesis, and thrombogenicity of the subendothelium was studied by perfusion in a Baumgartner annular chamber. Evening primrose oil reduced hypercholesterolemia (from 29 +/- 3 to 12 +/- 2 nmol/l), increased HDL-cholesterol (from 0.5 +/- 0.06 to 0.8 +/- 0.09 nmol/l) and doubled prostacyclin synthesis (from 2.7 +/- 2 to 6.2 +/- 0.7 ng/mg aorta) in rabbits on the hyperlipemic diet, reduced subendothelial surface occupied by platelets (from 6.9 +/- 0.4 to 4.8 +/- 0.3%), and reduced human platelet adhesion on the subendothelium (from 53.3 +/- 6% to 38 +/- 8%, respect to total occupation). Morphological analyses showed that evening primrose oil diminished endothelial lesions caused by the atherogenic diet, reducing area of the arterial wall (from 6.9 +/- 0.2 to 4.7 +/- 0.2 microm2 x 10(6)) and the degree of neointimal proliferation (from 0.6 +/- 0.02 to 0.4 +/- 0.09 microm2 x 10(6)). We conclude that in our experimental model, this dietary supplement enhanced the antithrombotic capacity of the endothelium, reduced subendothelial thrombogenicity, and diminished the extent of vascular wall lesions caused by the hyperlipemic diet.     

Upregulation of alpha GM-CSF-receptor in nonatopic asthma but not in atopic asthma

BACKGROUND: Intrinsic asthma is characterized by an increased number of activated eosinophils and macrophages and an increased expression of the hematopoietic growth factor granulocyte-macrophage colony-stimulating factor (GM-CSF) in the bronchial mucosa. OBJECTIVE: This study was carried out to investigate the expression of alpha GM-CSF receptor (alpha GM-CSFr) messenger RNA and protein in the bronchial mucosa of patients with intrinsic or atopic asthma and of control subjects and to correlate the expression of alpha GM-CSFr to the number of EG2+ cells (eosinophils) and CD68+ cells (macrophages) and pulmonary function. METHODS: Nineteen patients with stable asthma (9 with atopic and 10 with intrinsic asthma) and 22 normal control subjects (12 atopic and 10 nonatopic subjects) were recruited, and FEV1 (percent predicted) and PC20 were measured before bronchoscopy. Endobronchial biopsy specimens were obtained and examined for membrane-bound alpha GM-CSFr by using in situ hybridization and immunocytochemistry. RESULTS: alpha GM-CSFr mRNA- and protein-positive cells were identified in biopsy specimens from all four groups studied. There was no significant difference in the number of cells expressing alpha GM-CSFr mRNA and protein in patients with atopic asthma compared with atopic and nonatopic control subjects. However, the numbers of alpha GM-CSFr mRNA- and protein-positive cells were significantly higher in nonatopic patients with asthma compared with atopic patients with asthma and atopic and nonatopic control subjects (p < 0.001). In the patients with intrinsic asthma, the number of alpha GM-CSFr mRNA-positive cells per millimeter of basement membrane correlated with numbers of CD68+ cells (r2 = 0.87, p < 0.001) but not with EG2+ cells, and colocalization studies demonstrated that 80% of the cells expressing alpha GMCSFr mRNA were CD68+. The expression of GM-CSF was also significantly increased in patients with intrinsic asthma compared with those with atopic asthma and control subjects (p < 0.05). In addition, in intrinsic asthma, there was a correlation between alpha GM-CSFr mRNA and FEV1 (r2 = 0.61, p < 0.05). CONCLUSION: These results demonstrate that elevated numbers of cells expressing alpha GM-CSFr can be detected in nonatopic asthma but not in atopic asthma and suggest that this increased expression is predominantly macrophage-associated and may play an important pathophysiologic role in intrinsic asthma.     

On the low-rate Shannon limit for binary intersymbol interference channels

For a discrete-time, binary-input, Gaussian channel with finite intersymbol interference, we prove that reliable communication can be achieved if, and only if, E/sub b//N/sub 0/>log2/G/sub opt/, for some constant G/sub opt/ that depends on the channel. To determine this constant, we consider the finite-state machine which represents the output sequences of the channel filter when driven by binary inputs. We then define G/sub opt/ as the maximum output power achieved by a simple cycle in this graph, and show that no other cycle or asymptotically long sequence can achieve an output power greater than this. We provide examples where the binary input constraint leads to a suboptimality, and other cases where binary signaling is just as effective as real signaling at very low signal-to-noise ratios.     

Clinical results of primary intramedullary osteosynthesis with the unreamed AO/ASIF tibial intramedullary nail of open tibial shaft fractures

From 04/91 to 06/96 sixty-nine open fractures of the tibia were primarily treated on the day of the accident with unreamed nailing (UTN, Synthese). The distributions of fracture type according to the AO classification and of soft tissue injury according to Gustilo were as follows: fracture type: A: 28%, B: 52%, C: 20%; soft tissue injury: I: 30%, II: 28%, IIIA: 12%, IIIB: 12%, IIIC: 6%. Of the 65 fractures assessed 46 (71%) healed within 18 weeks without secondary intervention. There was delayed healing in three fractures requiring secondary conversion to reamed nailing. Eight fractures (12%) developed pseudarthrosis of which five (8%) healed uneventfully. Deep infections was manifest in four fractures (6%). Three of these infections developed after secondary intervention to treat pseudarthrosis. Seven of the eight pseudarthroses and three of the four infections healed eventually. Revision procedures were necessary in 11 patients (17%) to deal with disturbed fracture healing or infection (10 reamed nailing procedures, three cancellous bone grafts, and one of each of the following: sequestrectomy, fibular osteotomy, plate fixation, external fixator, monorail procedure). The results show that the same good infection rates were achieved for the UTN as for the external fixator. The advantages of the UTN are, however, a lesser need for secondary intervention and greater patient comfort. Therefore, we find the UTN to be a good alternative to the external fixator in the treatment of open fractures with severe soft tissue damage.