The effect of stand origin on the wood structure of Norway spruce

A study was carried out to compare the annual ring width, latewood share and density of spruce wood from the north eastern a nd south w estern ranges of Norway spruce. Twelve trial plots were located in the north eastern range, while within the south w estern range eight trial plots were established in the Sudeten Mountains and twelve trial plots in the Carpathian Mountains. On ev ery trial plot fifteen spruce trees were chosen, from which increment cores were sampled using a Pressler borer. Next, the increment cores had their surfaces smoothed and measurements were made of the width of annual rings, latewood zones and the share of latewood. Then the cores were divided into 2 cm sections, for which the relative wood density was determined. The analyses indicate that annual rings were wider in trees growing within the north eastern range than in those from the south western range an d the Kruskal Wallis test showed the differences to be statistically significant. T he latewood share followed an opposite pattern: t he wood from the Mazury region had a higher proportion of latewood than the wood from the mountainous areas and the statist ical test again indicated that the differences were significant. The analys i s of wood density showed slight differences between the density of wood from the north eastern and south western ranges, but in this case the Kruskal Wallis test showed the differe nces to be statistically insignificant

Advanced analysis of steel frames with effects of joint deformability and partial strength accounted for

The paper summarises the current progress in methods of advanced analysis for design of frames with semirigid joints. The methods presented in the paper belong to general secondâ€order refined plasticâ€hinge methods that allow for the combined effects of joint stiffness degradation and distributed plasticity along the member length as well as across the member sections. The advanced analysis for steel frame design, proposed by the authors, is based on the springâ€inâ€series model. The effect of joint semiâ€rigidity and partial strength is taken care of by specifying certain values of the initial stiffness, ultimate moment and the shape factor of the momentâ€rotation characteristic for the spring representing the joint. The effect of imperfections affecting the performance of imperfect structural members in compression is modelled by the application of a simplified tangent modulus concept combined with the reduction of the initial value of the elasticity modulus. The effect of residual stresses is taken care of by specifying certain values of the shape parameter for the momentâ€rotation characteristic of the spring representing the gradual yielding of the member. It is dependent upon the crossâ€section type and fabrication method (ie upon the residual stress pattern resulting from rolling or welding processes). A case study analysis is presented. Concluding remarks referring to the application of advanced analysis in design, pertaining to the study case considered, are drawn. First Published Online: 14 Oct 201

Cranial and ventricular size following shunting or endoscopic third ventriculostomy (ETV) in infants with aqueductal stenosis: further insights from the International Infant Hydrocephalus Study (IIHS)

Purpose The craniometrics of head circumference (HC) and ventricular size are part of the clinical assessment of infants with hydrocephalus and are often utilized in conjunction with other clinical and radiological parameters to determine the success of treatment. We aimed to assess the effect of endoscopic third ventriculostomy (ETV) and shunting on craniometric measurements during the follow-up of a cohort of infants with symptomatic triventricular hydrocephalus secondary to aqueductal stenosis. Methods We performed a post hoc analysis of data from the International Infant Hydrocephalus Study (IIHS)-a prospective, multicenter study of infants (< 24 months old) with hydrocephalus from aqueductal stenosis who were treated with either an ETV or shunt. During various stages of a 5-year follow-up period, the following craniometrics were measured: HC, HC centile, HCz-score, and frontal-occipital horn ratio (FOR). Data were compared in an analysis of covariance, adjusting for baseline variables including age at surgery and sex. Results Of 158 enrolled patients, 115 underwent an ETV, while 43 received a shunt. Both procedures led to improvements in the mean HC centile position andz-score, a trend which continued until the 5-year assessment point. A similar trend was noted for FOR which was measured at 12 months and 3 years following initial treatment. Although the values were consistently higher for ETV compared with shunt, the differences in HC value, centile, andz-score were not significant. ETV was associated with a significantly higher FOR compared with shunting at 12 months (0.52 vs 0.44;p = 0.002) and 3 years (0.46 vs 0.38;p = 0.03) of follow-up. Conclusion ETV and shunting led to improvements in HC centile,z-score, and FOR measurements during long-term follow-up of infants with hydrocephalus secondary to aqueductal stenosis. Head size did not significantly differ between the treatment groups during follow-up, however ventricle size was greater in those undergoing ETV when measured at 1 and 3 years following treatment