Bite force and its correlation with long face in children and youth

Background: Bite force is one of the indicators of proper functioning of the stomatognathic system, and its value may have diagnostic significance in disorders of the musculoskeletal system of facial bones. The aim of the study was to evaluate the relationship between gender and age, and bite force in patients with high­-angle vertical relationship of jaws and cranial bases. Materials and methods: The study group comprised 66 subjects aged 7–17 years, in whom the mandibular jaw base line and maxillary jaw-base line (ML-NL) angles were greater than 27° and the mandibular jaw-baseline and the anterior cranial base line (ML-NSL) above 33°, and a control group (n = 54) aged 7–16 years, in which the ML-NL angles were 20.0 ± 7.0° and ML-NSL 28.0 ± 5.0°. For measuring the bite force, a Japanese digital dynamometer Imada type ZPS-LM­-2000N was used. Results: In the study group no statistically significant correlation between the bite force and gender was shown, and in the control group the average bite force on the right side was significantly different for boys and girls, whereas for boys it was higher. In the study group the relationship between the age and average and maximum bite force on the right and left side was significant. In the group of people with a high-angle relationship of bases of jaws and skull no statistically significant correlation between the bite force and gender was shown. Conclusions: The was no effect of gender on the bite force in all subjects up to 18 years of age, both in patients with a high-angle and normal relationship of bases of jaws and skull. In people with a high-angle relationship of bases of jaws and cranium masticatory forces increase with age

The relationship between selected parameters of a cephalometric analysis determining the vertical morphology of facial skeleton and bite force

Background: There are few studies devoted to an assessment of the relation between bite force and detailed results of cephalometric analysis that determine craniofacial structure. The purpose of the study was to assess the correlation between the selected criteria determining the craniofacial structure and bite force in patients with normal and increased vertical relation of the bases of jaws and skull. Materials and methods: The study material included 120 patients, aged between 7 and 17 years, who presented for examination and possible orthodontic treatment. The patients were divided into a study group and a control group. The basis of this division were ML-NL and ML-NSL angles, according to Segner’s and Hasund’s analysis standards, respectively: above 27° and above 30° in the study group, and 20.0 ± 7.0° and 28.0 ± 5.0° in the control group. Bite force was tested using a digital dynamometer calibrated in Newtons. The measurement was performed at the level of the first permanent molars. Vertical relations were assessed using the following cephalometric measurements: ML-NSL, ML-NL, NL-NSL, N-Me, Sp-Me, SpMe:NMe, ms-NL, SGo:NMe. Results: Bite force was not found to be dependent on the lower anterior face height (Sp-Me), the ratio of anterior lower to total anterior face height (SpMe:NMe), and NL-NSL angle both in patients with abnormal and normal relations of bases of jaws and skull. Although statistically non-significant, the average mean and maximum bite force values were found to be lower in patients with high-angle relation of bases of jaws and skull than in subjects with normal relation of bases of jaws and skull. Conclusions: Among the selected parameters determining the vertical craniofacial structure, the rear height of the alveolar process (ms-NL) exerts the greatest influence on bite force in both patients with increased and normal vertical relation of bases of jaws and skull, and with an increase in the value of ms-NL, bite force is reduced.

Comparative study of radiation-induced damage in magnesium aluminate spinel by means of IL, CL and RBS/C techniques

International audienceA comparative study of damage accumulation in magnesium aluminate spinel (MgAl2O4) has been conducted using ionoluminescence (IL), cathodoluminescence (CL) and Rutherford Backscattering Spectrometry/channeling (RBS/C) techniques. MgAl2O4 single crystal and polycrystalline samples were irradiated with 320 keV Ar+ ions at fluencies ranging from 1 × 1012 to 2 × 1016 cm−2 in order to create various levels of radiation damage. RBS/C measurements provided quantitative data about damage concentration in the samples. These values were then compared to the luminescence measurements. The results obtained by IL and RBS/C methods demonstrate a two-step character of damage buildup process. The CL data analysis points to the three-step damage accumulation mechanism involving the first defect transformation at fluencies of about 1013 cm−2 and second at about 1015 cm−2. The rate of changes resulting from the formation of nonluminescent recombination centers is clearly nonlinear and cannot be described in terms of continuous accumulation of point defects. Both, IL and CL techniques, appear as new, complementary tools bringing new possibilities in the damage accumulation studies in single- and polycrystalline materials

Observations of the Sun using LOFAR Baldy station

We report first results of solar spectroscopic observations carried out with the Baldy LOFAR (LOw-Frequency ARray) station, Poland from October 2016 to July 2017. During this time, we observed different types of radio emission: type I and type III radio bursts. Our observations show that the station is fully operational and it is capable to work efficiently in the single station mode for solar observations. Furthermore, in this paper we will briefly describe the observational technique and instrument capabilities and show some examples of first observations. (C) 2018 COSPAR. Published by Elsevier Ltd. All rights reserved.Peer reviewe

Grey squirrels in central Italy: a new threat for endemic red squirrel subspecies

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The relationship between facial skeleton morphology and bite force in people with a normal relation of the bases of jaws and skull

Background: Better knowledge on the relationship between craniofacial structure and bite force may serve as a reference point for prophylactic and therapeutic activities targeted at developmental age patients. The aim of the study was to assess the correlation between facial skeletal morphology and bite force. Materials and methods: The study included 54 subjects aged 7–16 years with a normal relation of the bases of jaws and skull, according to Segner’s and Hasund’s analysis standards (ML-NL and ML-NSL angles values were 20.0 ± 7.0° and 28.0 ± 5.0°, respectively). The study group included patients who volunteered to diagnosis and possible orthodontic treatment. Bite force was tested with a digital dynamometer calibrated in Newtons. The measurement was performed at the level of the first permanent molars. Cephalometric analysis was based on lateral cephalometric radiographs. The vertical relations were assessed using the following measurements: ML-NSL, ML-NL, NL-NSL, N-Me, Sp-Me, SpMe:NMe, ms-NL, SGo:NMe. Results: Bite force does not depend on the following factors: lower anterior face height (Sp-Me), lower anterior face height to total anterior face height ratio (SpMe:NMe), posterior to anterior face height ratio (SG0:NMe), and the value of ML-NL, ML-NSL and NL-NSL angles. Conclusions: The posterior height of the maxilla alveolar process (ms-NL) exerts the greatest influence on bite force in people with a normal relation of the bases of jaws and skull: with an increase in ms-NL value bite force is reduced

Neural modelling for calculating the heat transfer coefficient and required isolation layer of wall barier

W referacie przedstawiono zastosowanie sztucznych sieci neuronowych do obliczania współczynnika przenikania ciepła U oraz model odwrotny, polegający na obliczaniu grubości warstwy izolacyjnej przy zadanym współczynniku. Opisano metodykę sporządzenia zbioru uczącego sztuczne sieci neuronowe oraz opisano zbiór przetestowanych sieci neuronowych. Metody sztucznej inteligencji, w tym sztuczne sieci neuronowe, pozwalają uwzględnić w obliczeniach wiele zjawisk i procesów trudnych do opisu matematycznego ze względu na swoją nieliniowość, stąd uzyskane modele neuronowe będą uzupełniane w przyszłości o dodatkowe parametry obliczeniowe.The report presents the usage of artificial neural networks to calculate heat transfer coefficient U and the opposite model, which consists on calculating the thickness of the isolation layer with given coefficient. The methodology of making a set teaching artificial neural networks and the set of tested neural networks were described. The methods of artificial intelligence, including neural networks, let include in calculations many phenomena and processes hard to describe mathematically because of their nonlinearity, so obtained neural models will be completed by additional computable parameters in future

Electrical Conductivity of Ethylene Glycol Based Nanofluids with Different Types of Thulium Oxide Nanoparticles

The paper presents experimental investigation on electrical conductivity of thulium oxides-ethylene glycol (Tm₂O₃-EG) nanofluids based on nanoparticles with three different sizes, and prepared in different conditions. Nanofluids were prepared with two-step method with use of the nanoparticles obtained by precipitation method. Measurements were conducted at constant temperature 293.15 K for various mass concentrations from 0% to 20% with 5% step. The electrical conductivity was measured using conductivity meter MultiLine 3410 (WTW GmBH, Weilheim, Germany) and temperature was stabilized in a water bath MLL 547 (AJL Electronic, Cracow, Poland). The results indicate that increase in mass concentration of nanoparticles in base fluid causes increase in electrical conductivity of Tm₂O₃-EG nanofluids. The enhancement in electrical conductivity of nanosuspensions of thulium oxide is dependent on particle size

Measurements and diagnostics of a laser beam as a manufacturing machine tool

Omówiono podstawowe dla jakości procesu parametry wiązki laserowej takie jak: długość Rayleigha; przewężenie wiązki; współczynniki jakości K, M2 i BPP; rozkład gęstości mocy oraz kaustykę. Opisano metody pomiarowe wiązek dużej mocy bazujące na wirującej igle pomiarowej oraz akwizycji obrazu przez matrycę CCD/CMOS. Przedstawiono wyniki pomiarów wykonanych aparaturą FocusMonitor firmy Primes dla systemów obróbkowych wyposażonych m.in. w lasery: diodowy 4 kW, dyskowy 2 kW oraz gazowy CO2 2 kW. Przeanalizowano uzyskane wyniki oraz powtarzalność pomiarów. Pokazano charakterystyczne problemy będące skutkiem aberracji w torze optycznym - astygmatyzm wiązki i zjawisko "focus shift" oraz omówiono najczęstsze wady systemów laserowych.Laser beam as a machine tool for manufacturing has to keep its parameters just as classic mechanical machine tools. The paper describes the following laser beam parameters essential for processing quality: Rayleigh length; beam waist; K, M2 and BPP beam quality factors; power density distribution and beam caustic [2]. The main parameters are presented in Fig. 1. Actual measurement methods for the listed above laser beam parameters that comply with the ISO 11146 recommendations are described. That concerns scanning the laser beam with a rotating tip [9] as a first method and acquiring the image of the laser beam intensity distribution projected on the CCD or CMOS photosensitive matrix [10] as a second method. Principles of both methods are shown in Fig. 2. Different laser machine systems equipped with, i.a.: 4 kW diode laser, 2 kW disc laser, 2kW CO2 laser has been measured by Primes FocusMonitor and analysed (Tab. 2) The measurement repeatability has been calculated for a specified setting of a P=1 kW disc laser beam emission and presented in Tab. 3. Characteristic problems caused by optical path aberrations - astigmatisms (Fig. 4) and focus shift (Fig. 5) as well as other common laser systems failures are discussed