A PVDF Sensor for the In-situ Measurement of Stress Intensity Factors During Fatigue Crack Growth

AbstractSeveral analytical and numerical studies of inverse analysis are performed to verify the feasibility and accuracy of the proposed K-sensor. At first, the application to cracks in sheets under in-plane stresses is investigated and compared with the analytical solution for the GRIFFITH's crack under mixed mode. It was found that the convergence radius, where the electrodes have to be placed, must be smaller than half of the crack length, which is sufficient for real cracks of several millimeters. The obtained accuracy of crack tip location and (KI, KII)-factors is better than 1%. Second, the technique is applied to cracks in thin-walled plates of KIRCHHOFF type under bending and torsion moments. In this case, the plate intensity factors (k1, k2) are of interest. Again, the inverse identification procedure is studied by synthetic analytical and numerical solutions of simple crack configurations. Due to the assumptions of the KIRCHHOFF plate model, the sensors have to be placed outside a radius of 3 times plate thickness h. The obtained accuracy in position and intensity factors is quite sufficient as well. The practical realization of the K-factor sensor requires good electric signal measurement and amplification. Its experimental testing on components is ongoing work

Distribution of Craniofacial Variables in South Dalmatian and Middle Croatian Populations

The objective of the present work was to determine some relevant craniofacial parameters, particularly in relation to sex, for the study of the distribution of basic head and face types, and to investigate craniofacial and morphological differences between two population samples. The study sample comprised 100 subjects of both sex aged 18 to 30 from South Dalmatia and 200 subjects from Middle Croatia. Eight basic craniofacial variables were measured to obtain head, forehead and face indexes. The data indicate that average values of all variables can be used as standard craniofacial parameters for the examined population groups. All the craniofacial variables are considerably higher in men than in women (p < 0.05). In the South Dalmatian population mesocephalia (48.0%) and leptoprosopia (82.0%) prevail, while in the Middle Croatian population the brachycephalia (62.0%), and euriprosopia (73.5%) are present to a greater degree. The most significant craniofacial and morphological differences between the examined study samples are head width (Eu–Eu), face width (Zy–Zy), and forehead height (Tr–N). They were found to be statistically significant in the examined Middle Croatian population (p < 0.05). The presented measurements are highly relevant to orthodontic diagnostics and therapy

Sublingual allergen immunotherapy with a liquid birch pollen product in patients with seasonal allergic rhinoconjunctivitis with or without asthma

Background: Sublingual allergen immunotherapy (SLIT) has been demonstrated to be both clinically efficacious and safe. However, in line with the current regulatory guidance from the European Medicines Agency, allergen immunotherapy (AIT) products must demonstrate their efficacy and safety in pivotal phase III trials for registration. Objective: We sought to investigate the efficacy and safety of sublingual high-dose liquid birch pollen extract (40,000 allergy units native [AUN]/mL) in adults with birch pollen allergy. Methods: A randomized, double-blind, placebo-controlled, parallel-group multicenter trial was conducted in 406 adult patients with moderate-to-severe birch pollen-induced allergic rhinoconjunctivitis with or without mild-to-moderate controlled asthma. Treatment was started 3 to 6 months before the birch pollen season and continued during the season in 40 clinical study centers in 5 European countries. For primary end point assessment, the recommended combined symptom and medication score of the European Academy of Allergy and Clinical Immunology was used. Secondary end points included quality-of-life assessments, immunologic parameters, and safety. Results: Primary efficacy results demonstrated a significant (P < .0001) and clinically relevant (32%) reduction in the combined symptom and medication score compared with placebo after 3 to 6 months of SLIT. Significantly better rhinoconjunctivitis quality-of-life scores (P < .0001) and the patient's own overall assessment of his or her health status, including the visual analog scale score (Euro Quality of Life Visual Analogue Scale; P = .0025), were also demonstrated. In total, a good safety profile of SLIT was observed. Conclusion: This study confirmed both the clinical efficacy and safety of a sublingual liquid birch pollen extract in adults with birch pollen allergy in a pivotal phase III trial (EudraCT: 2013-005550-30; ClinicalTrials. gov: NCT02231307)

Dynamic Effects of Food Consistency on Chewing Motions

The purpose of the study was to find evidence of how different types of food consistency affect chewing motions, especially the forward, downward and sidewise extents of motion of the lower jaw. Nineteen individuals with intact tooth sequence, aged from 20 to 37 years, were asked to chew three types of food of different consistency (banana, bread, carrot). The motions of the lower jaw were recorded by ELITE system, i.e. the measurement instrument that by stereo-photo-grametric procedures calculates space co-ordinates of markers on faces of the study subjects. The system enables continuous recording of lower jaw motions in three dimensions, without any possibility of the study subjects’ influencing the operation of the instrument, which significantly decreases the possibility of error. Study results have shown that in all 19 subjects a greater food consistency increases the extent of chewing motion. In each individual study subject different average values were found for equal shifts of lower jaw when chewing the same type of food. Although varying from subject to subject, the chewing cycle depends to a great extent on food consistency. By increasing the consistency of a bite, the extent of lower jaw motion has increased in every single study subject

Covariance systems

We introduce new definitions of states and of representations of covariance systems. The GNS-construction is generalized to this context. It associates a representation with each state of the covariance system. Next, states are extended to states of an appropriate covariance algebra. Two applications are given. We describe a nonrelativistic quantum particle, and we give a simple description of the quantum spacetime model introduced by Doplicher et al.Comment: latex with ams-latex, 23 page

Longitudinal validity of spirometers--a challenge in longitudinal studies.

Pulmonary function testing (PFT) in longitudinal studies involves the repeated use of spirometers over long time periods. We assess the comparability of PFT results taken under biologic field conditions using thirteen certified devices of various technology and age. Comparability of measurements across devices and over time is relevant both in clinical and epidemiological research. Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1) and Forced Expiratory Flow 50% (FEF50) were compared before and after the data collection of the Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) and the European Community Respiratory Health Survey (ECRHS) cohort studies. Three test series were conducted with 46, 50 and 56 volunteers using various combinations of spirometers to compare the eight flow-sensing spirometers (Sensormedics 2200) used in the SAPALDIA cross-sectional and follow-up, two new flow-sensing instruments (Sensormedics Vmax) and three volume displacement spirometers (two Biomedin/Baires and one Sensormedics 2400). The initial comparison (1999/2000) of eight Sensormedics 2200 and the follow-up comparison (2003) of the same devices revealed a maximal variation of up to 2.6% for FVC, 2.4% for FEV1 and 2.8% for FEF50 across devices with no indication of systematic differences between spirometers. Results were also reproducible between Biomedin, Sensormedics 2200 and 2400. The new generation of Sensormedics (Vmax) gave systematically lower results. The study demonstrates the need to conduct spirometer comparison tests with humans. For follow-up studies we strongly recommend the use of the same spirometers

Measurement of Magnetic Field in Dentistry

The principal objective was to measure the magnetic fields occurring in dental surgeries at simultaneous subtraction of direct ground component of the magnetic field. A specifically designed instrument with the Hall probe was used for the measurement. It consisted of two amplifiers and a low frequency filter. Its task was to measure mean square values of the field (RMS) dependent on the position in space. Qualitative and quantitative analyses of the investigated variables enabled making conclusions about the magnetic fields in dental surgeries. A number of studies have shown that many dental instruments produce radiation with magnetic field higher than 40 G, at a significant decrease in power of the magnetic field with increasing distance from the source. It has also been reported that instruments of older generations produce stronger magnetic fields than do the new ones