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A beam/adhesive-layer model is developed. For this model a closed-form solution method applicable to arbitrary boundary conditions is presented. This enables the solution of a large number of pract ...

Fracture behaviour of adhesive joints under mixed mode loading is analysed by using the beam/adhesive-layer (b/a) model, in which, the adherends are beamlike and the adhesive is constrained to a thin flexible layer between the adherends. The adhesive layer deforms in peel (mode I), in shear (mode II) or in a combination of peel and shear (mixed mode). Macroscopically, the ends of the bonded part of the joints can be considered as crack tips. The energy release rate of a single-layer adhesive joint is then formulated as a function of the crack tip deformation and the mode-mixity is defined by the shear portion of the total energy release rate. The effects of transversal forces and the flexibility of the adhesive layer are included in the b/a-model, which can be applied to joints with short crack length as well as short bonding length. The commonly used end-loaded unsymmetric semi-infinite joints are examined and closed-form solutions are given. In comparison to the singular-field model in the context of linear elastic fracture mechanics, the b/a-model replaces the singularity at the crack tip with a stress concentration zone. It is shown that the b/a-model and the singular-field model yield fundamentally different mode-mixities for unsymmetric systems. The presented closed-form b/a-model solutions facilitates parametric studies of the influence of unbalance in loading, unsymmetry of the adherends, as well as the flexibility of the adhesive layer, on the mode mixity of an adhesive joint.

Objective Maternal smoking has previously been associated with risk of stillbirth. If women who quit smoking reduce their risk of stillbirth, the hypothesis of a causal association would be supported. Design Prospective cohort study. Setting Nationwide study in Sweden. Population All primiparous women who delivered their first and second consecutive single births between 1983 and 2001, giving a total number of 526 691 women. Method A population-based Swedish study with data from the Medical Birth Registry, the Immigration Registry and the Education Registry. Logistic regression analyses were used to estimate odds ratios, using 95% confidence intervals. Main outcome measure Stillbirth in the second pregnancy. Results Compared with nonsmokers in both pregnancies, women who smoked during the first pregnancy but not during the second do not have an increased risk of stillbirth (OR 1.02; 95% CI 0.79–1.30), while corresponding risk among women who smoked during both pregnancies was 1.35 (95% CI 1.15–1.58). Conclusion The result supports that maternal smoking during pregnancy is causally associated with stillbirth risk. Smoking is a preventable cause of stillbirth, and smoking interventions is an important issue in antenatal care.

A traction-separation relation to model the fracture process is presented. The cohesive law captures the linear elastic and softening behaviour prior to fracture. It also allows for different fracture parameters, such as fracture energy, strength and critical separation in different mode mixities. Thus, the fracture process in mode I (peel), in mode II (shear) or in mixed mode (a combination of peel and shear) can be modelled without the limitation of a common fracture energy in peel and shear. Examples are given in form of FE- implementations of the normalised cohesive law, namely for the Unsymmetrical Double Cantilever Beam (UDCB) specimen and the Mixed-mode double Cantilever Beam (MCB) specimen. Both specimens are adhesively bonded and loaded in mixed-mode.

Summary Background : Systemic glucocorticosteroid therapy is effective in Crohn's disease, but is associated with side-effects. Budesonide has high topical anti-inflammatory activity, but considerably lower systemic activity than other oral glucocorticosteroids. Aim : To evaluate the systemic exposure to budesonide (controlled ileal release capsules) in children and adults with active Crohn's disease, and to assess the suppression of plasma cortisol. Methods : In an open label study, patients (eight children and six adults) with active Crohn's disease received 9 mg budesonide (Entocort capsules) orally once daily for 7 days. Plasma concentrations were determined on the seventh day of administration, and pharmacokinetic parameters were calculated. For reference, 0.5 mg budesonide was given intravenously separately. Plasma cortisol levels were compared with the pre-treatment baseline values. Results : Systemic exposure to budesonide (AUC0−24 h) after 1 week of oral administration was 41 ± 21 nmol/L × h (mean ± s.d.) in children and 35 ± 20 nmol/L × h in adults. The estimated systemic availability in children was 9 ± 5% and in adults 11 ± 7%. The mean plasma cortisol (AUC0−24 h) decreased by 64 ± 18% in children and by 50 ± 27% in adults. Conclusions : The systemic exposure, systemic availability and cortisol suppression after oral administration of 9 mg budesonide were similar in children and adults with active Crohn's disease. Budesonide was well tolerated and no clinically important safety-related findings were identified.

Increased concentration of nitric oxide (NO) metabolites, nitrite and nitrate, in the urine is a strong indication of ongoing small intestinal inflammation, which is a hallmark of the enteropathy of coeliac disease (CD). It has previously been shown that children with symptomatic, untreated CD have increased levels of NO oxidation products in their urine. The aim of this study was to investigate whether screening-detected, asymptomatic coeliac children display the same urinary nitrite/nitrate pattern.In a multicenter screening study, serum samples were collected from 7208 12-year-old children without previously diagnosed CD. Sera were analysed for anti-human tissue transglutaminase (tTG) of isotype IgA. Small bowel biopsy was performed in antibody-positive children, yielding 153 new cases of CD. In the screening-detected individuals, the sum of nitrite and nitrate concentrations in the urine was analysed and used as an indicator of NO production. For comparison, 73 children with untreated, symptomatic CD were studied.The nitrite/nitrate levels in children with screening-detected CD and those with untreated symptomatic CD did not differ significantly. Both groups had significantly increased urinary nitrite/nitrate concentrations compared to the children with normal small bowel biopsy (p 0.001). Children with screening-detected CD have increased production of NO just as children with untreated symptomatic CD. High NO metabolite levels in the urine may indicate a pathogenetic feature of CD and be a marker of major clinical importance.

Systemic glucocorticosteroid therapy is effective in Crohn's disease, but is associated with side-effects. Budesonide has high topical anti-inflammatory activity, but considerably lower systemic activity than other oral glucocorticosteroids.To evaluate the systemic exposure to budesonide (controlled ileal release capsules) in children and adults with active Crohn's disease, and to assess the suppression of plasma cortisol.In an open label study, patients (eight children and six adults) with active Crohn's disease received 9 mg budesonide (Entocort capsules) orally once daily for 7 days. Plasma concentrations were determined on the seventh day of administration, and pharmacokinetic parameters were calculated. For reference, 0.5 mg budesonide was given intravenously separately. Plasma cortisol levels were compared with the pre-treatment baseline values.Systemic exposure to budesonide (AUC0-24 h) after 1 week of oral administration was 41 +/- 21 nmol/L x h (mean +/- s.d.) in children and 35 +/- 20 nmol/L x h in adults. The estimated systemic availability in children was 9 +/- 5% and in adults 11 +/- 7%. The mean plasma cortisol (AUC0-24 h) decreased by 64 +/- 18% in children and by 50 +/- 27% in adults.The systemic exposure, systemic availability and cortisol suppression after oral administration of 9 mg budesonide were similar in children and adults with active Crohn's disease. Budesonide was well tolerated and no clinically important safety-related findings were identified.

The inner cars of pigeons have been irradiated by means of a Q-switched ruby laser with an output pulse energy of about 0.3 joule. Atrophy of the epithelium and changes in the bony and membranous labyrinth have been observed. The ability of the laser beam to penetrate thin slices of bone has been tested. The biological effect of the laser beam seems to be mainly thermal, but ultrasonic waves created in the focal spot may contribute.

Minute and reproducible inner-ear lesions were produced in surviving guinea pigs by using an argon laser. Preselected areas, mainly in the cochlea, were irradiated for 0.5-30 seconds at power densities at the focal spot of around 1 to 2 kW/cm2. the laser beam did not perforate the otic capsule but produced superficial changes. Beneath the impact point in the bone, a rounded lesion was observed in the vascular stria. Damage to the organ of Corti of varying extent occurred, depending on the energy dosage delivered. the organ of Corti in the impact area was characterized by either a complete loss or a reduced number of lipid granules in the Hensen cells. Hair-cell changes covering about one-third of a coil were frequently noted. Variations in the appearance of the cilia after irradiation are presented. Expansions of the tips of the cilia on the outer hair cells are described. the outer hair cells proved to be more affected by the laser irradiation than the inner hair cells. Scanning electron microscopy and p...

Stimulated emission from gas discharge tubes built up of ceramic disc capacitors (C = 3 000 pF) separated by electrodes and having a central hole (discharge channel) has been studied. Nitrogen has been used as test gas. It is shown that the output power density is appreciably higher from this tube when fed by a high voltage pulse generator than from an ordinary straight tube with end electrodes. 230 kW pulses (superradiant mode without mirrors) have been observed from a tube 7 mm in bore and 102 mm long at at nitrogen pressure of 175 torr. The pulse duration is approximately 2 ns. It is further shown that the stimulated emission occurs during breakdown. In a similar tube with aluminium oxide discs (εr = 8) instead of the disc capacitors, laser action has been observed at considerably higher pressure. In air at atmospheric pressure an output of 25 kW has been achieved from a tube 4 mm in bore and 102 mm long. The pulse duration is in this case approximately 1 ns.

The design and performance of an electrodeless plasma gun is described. The driving circuit consists of a capacitor feeding a single primary turn, placed behind the flat end wall of a Pyrex tube. Max. primary current is 65 kA with a risetime of 0.35 μs. The discharges have been studied by means of magnetic pick-up loops, a Kerrcell camera, and by spectroscopical measurements. Plasma rings of comparatively high purity and with velocities up to 5 cm/μs have been produced. By means of a longitudinal magnetic field, strength up to 1200 gauss, the burst of plasma has been contracted to the center of the tube.

The design principles of a pulse generator using circular plate capacitors to generate high voltage pulses is described. The properties of such capacitors, discharged in the centre, are utilized to get a fast risetime whilst maintaining a flexible and compact design. The properties of generators with output voltages of 300 kV, 600 kV and 1.2 MV at load impedance of 40 ohms, 60 ohms and 120 ohms respectively, have been studied. The duration of the voltage pulse is approximately 20 nanoseconds.

Superradiant, stimulated emission at 3371 A has been observed from spark discharges in air at atmospheric pressure. This emission corresponds to transitions in the second positive band system of molecular nitrogen. Duration of the emitted laser pulse is about 0.6 nsec and peak power output is about 2 W.

Design and performance data of a field emission X-ray flash tube are presented. The electrode assembly is exchangeable. It is thus possible to adapt the tube impedance to the voltage source or to replace the anode tip when necessary. The tube has been tested in the voltage range 100-1 200 kV; the pulse width at 1 200 kV is typically 10 ns and the penetration 5 cm of steel at 1 m.

The design and construction of a simple graphite shunt with a resistance in the range 10-100 mΩ is described. These shunts show typically less than 10% overshoot to pulses with approximately 0.5 nsec rise time and may be used for measurements of 10 A-10 kA current transients with characteristic times in the range 0.3 nsec-1 μsec in combination with travelling wave tube oscilloscopes.