scholarly journals Electromagnetic Energy Absorption in a Head Approaching a Radiofrequency Identification (RFID) Reader Operating at 13.56 MHz in Users of Hearing Implants Versus Non-Users

Sensors ◽  
2019 ◽  
Vol 19 (17) ◽  
pp. 3724 ◽  
Author(s):  
Patryk Zradziński ◽  
Jolanta Karpowicz ◽  
Krzysztof Gryz
Keyword(s):  
Specific Absorption Rate ◽  
Acoustic Sensor ◽  
Bonferroni Correction ◽  
Worst Case ◽  
Rfid Reader ◽  
Significant Difference ◽  
Ellipsoidal Model ◽  
Radiofrequency Identification ◽  
Bone Anchored Hearing Aid ◽  
Biophysical Effects

The aim of this study was to model the absorption in the head of an electromagnetic field (EMF) emitted by a radiofrequency identification reader operating at a frequency of 13.56 MHz (recognized as an RFID HF reader), with respect to the direct biophysical effects evaluated by the specific absorption rate (SAR), averaged over the entire head or locally, over any 10 g of tissues. The exposure effects were compared between the head of a user of a hearing implant with an acoustic sensor and a person without such an implant, used as a referenced case. The RFID HF reader, such as is used in shops or libraries, was modeled as a loop antenna (35 × 35 cm). SAR was calculated in a multi-layer ellipsoidal model of the head—with or without models of hearing implants of two types: Bonebridge (MED-EL, Austria) or bone anchored hearing aid attract (BAHA) (Cochlear, Sweden). Relative SAR values were calculated as the ratio between the SAR in the head of the implant user and the non-user. It was found that the use of BAHA hearing implants increased the effects of 13.56 MHz EMF exposure in the head in comparison to non-user—up to 2.1 times higher localized SAR in the worst case exposure scenario, and it is statistically significant higher than when Bonebridge implants are used (Kruscal–Wallis test with Bonferroni correction, p < 0.017). The evaluation of EMF exposure from an RFID reader with respect to limits established for the implant non-user population may be insufficient to protect an implant user when exposure approaches these limits, but the significant difference between exposure effects in users of various types of implants need to be considered.

scholarly journals Assessing Diazinon Pollution in the Three Major Rivers Flowing into the Caspian Sea (Iran)

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 335
Author(s):  
Reza Dahmardeh Behrooz ◽  
Abbas Esmaili-sari ◽  
Magdalena Urbaniak ◽  
Paromita Chakraborty
Keyword(s):  
High Risk ◽  
Organophosphorus Pesticides ◽  
Aquatic Organisms ◽  
The United States ◽  
The Caspian Sea ◽  
Worst Case ◽  
Pollution Levels ◽  
Haraz River ◽  
Significant Difference ◽  
Medium Risk

The aim of this study was to investigate the seasonal and spatial variations in the concentrations of a widely used organophosphorous pesticide (OPP), diazinon, and the associated risk posed by this OPP in the surface water from the three largest rivers located in the northern province of Iran: the Haraz, the Talar and the Babolrood rivers. These rivers are located in the agriculture province of Mazandaran, and are exposed to high doses of organophosphorus pesticides, especially diazinon. The concentration of diazinon was determined using gas chromatography, while the potential risk posed by diazinon was elucidated using a Risk Quotient (RQ) calculated for general (RQm) and worst-case (RQex) scenarios. The obtained results demonstrated that the average diazinon concentrations ranged from 41 ± 76 ng/L in the Talar River and 57 ± 116 ng/L in the Haraz River, to 76.5 ± 145 ng/L in the Babolrood River, with a significant difference noted between summer and autumn seasons for all three rivers. For some stations, the concentration of diazinon is higher than the standard guidelines of Australian/New Zealand Guidelines for Fresh and Marine Water Quality (FMWQ) and the United States Criteria Maximum Concentration (CMC). The calculated RQs indicated a medium risk of diazinon, RQm = 0.73 and RQex = 2.27, in the Talar River; RQm = 1.02 and RQex = 2.49 in the Haraz River; and RQm = 1.35 and RQex = 4.54 in the Babolrood River. The overall exposure of diazinon was defined to have a high risk (RQm and RQex > 1); however, the summer sampling revealed a high risk (RQm and RQex > 1), while the autumn had a medium risk (RQm and RQex < 1). The obtained results revealed not only elevated concentrations of diazinon in the studied rivers but most importantly the high risk posed by this OPP for the aquatic organisms and the wellbeing of the whole river ecosystem. The current study showed that development and implementation of appropriate standards and regulations toward diazinon in countries such as Iran are required to reduce the pollution levels and risks related to elevated concentrations of the studied pesticide.

scholarly journals Cyclic fatigue resistance of 2Shape, Twisted File and EndoSequence Xpress nickel-titanium rotary files at intracanal temperature

2018 ◽  
Vol 12 (4) ◽  
pp. 283-287 ◽  
Author(s):  
Gülşah Uslu ◽  
Taha Özyürek ◽  
Mustafa Gündoğar ◽  
Koray Yılmaz
Keyword(s):  
Fatigue Resistance ◽  
Statistical Significance ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Bonferroni Correction ◽  
Significant Difference ◽  
Inner Diameter ◽  
The Difference ◽  
Number Of Cycles ◽  
Analyze Data

Background. The aim of this study was to compare the cyclic fatigue resistance of 2Shape, Twisted File (TF) and EndoSequence Xpress (ESX) nickel-titanium rotary files at intracanal temperature (35°C). Methods. Twenty 2Shape TS1 (25/.04), 20 TF (25/.04) and 20 ESX (25/.04) files were tested for cyclic fatigue at intracanal temperature (35°C). All the instruments were rotated in artificial canals which were made of stainless steel with an inner diameter of 1.5 mm, 60° angle of curvature and a radius curvature of 5 mm until fracture occurred; the time to fracture was recorded in seconds using a digital chronometer and the number of cycles to fracture (NCF) for each file was calculated. Kruskal-Wallis test with Bonferroni correction was performed to statistically analyze data using SPSS 21.0. Statistical significance was set at P<0.05. Results. NCF values revealed that the 2Shape had significantly the highest cyclic fatigue resistance, followed by TF and ESX at intracanal temperature (P<0.05). The difference was significant between the TF and ESX groups (P<0.05). There was no significant difference among the 2Shape, TF and ESX files with respect to the lengths of the fractured file fragments (P>.05). Conclusion. Within the limitations of present study, it was concluded that the cyclic fatigue resistance of 2Shape files at the intracanal temperature is higher than that of TF and ESX files.

Multiphase Transient Slugging Flow in Subsea Oil and Gas Production

2016 ◽  
Author(s):  
Zhenhua Zhang ◽  
Longbin Tao
Keyword(s):  
Data Analysis ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Slug Flow ◽  
Field Data ◽  
Oil And Gas ◽  
Gas Production ◽  
Worst Case ◽  
Oil And Gas Production ◽  
Significant Difference

Slug flow in horizontal pipelines and riser systems in deep sea has been proved as one of the challenging flow assurance issues. Large and fluctuating gas/liquid rates can severely reduce production and, in the worst case, shut down, depressurization or damage topside equipment, such as separator, vessels and compressors. Previous studies are primarily based on experimental investigations of fluid properties with air/water as working media in considerably scaled down model pipes, and the results cannot be simply extrapolated to full scale due to the significant difference in Reynolds number and other fluid conditions. In this paper, the focus is on utilizing practical shape of pipe, working conditions and fluid data for simulation and data analysis. The study aims to investigate the transient multiphase slug flow in subsea oil and gas production based on the field data, using numerical model developed by simulator OLGA and data analysis. As the first step, cases with field data have been modelled using OLGA and validated by comparing with the results obtained using PIPESYS in steady state analysis. Then, a numerical model to predict slugging flow characteristics under transient state in pipeline and riser system was set up using multiphase flow simulator OLGA. One of the highlights of the present study is the new transient model developed by OLGA with an added capacity of newly developed thermal model programmed with MATLAB in order to represent the large variable temperature distribution of the riser in deep water condition. The slug characteristics in pipelines and temperature distribution of riser are analyzed under the different temperature gradients along the water depth. Finally, the depressurization during a shut-down and then restart procedure considering hydrate formation checking is simulated. Furthermore, slug length, pressure drop and liquid hold up in the riser are predicted under the realistic field development scenarios.

scholarly journals Artificial teeth: evaluation of wear resistance, microhardness and composition

2015 ◽  
Vol 63 (3) ◽  
pp. 263-270 ◽  
Author(s):  
Matheus GRANDO ◽  
Lívia Muniz PACHECO ◽  
Daniela Maffei BOTEGA ◽  
Luciana Mayumi HIRAKATA ◽  
Juliana Balbinot HILGERT
Keyword(s):  
Wear Resistance ◽  
Acrylic Resin ◽  
Knoop Hardness ◽  
Composition Analysis ◽  
Bonferroni Correction ◽  
Hardness Tester ◽  
Significant Difference ◽  
Microhardness Testing ◽  
Wear Evaluation ◽  
Artificial Teeth

Objective: To evaluate the Knoop hardness, composition, and wear resistance of acrylic-resin artificial teeth exposed to mechanical toothbrushing. Methods: Artificial teeth from three commercial brands - Biotone, Trilux, and Soluut PX - were used. From each brand, 10 teeth were selected for wear evaluation after mechanical brushing, 10 for microhardness testing, and 5 for composition analysis. Specimens underwent 55,000 brushing cycles, under a 200-g load and at a frequency of 250 cycles per minute, using a soft-bristled toothbrush (IndicatorPlus 30, Oral-B) soaked in a 1:1 toothpaste/water slurry (Oral B Pró Saúde). Microhardness testing was performed using a 25-g load for 15 seconds in an HMV-2 hardness tester (Shimadzu). The composition of teeth from different brands was determined by scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDS) (Jeol JSM 5800). Results: Wear results after mechanical brushing were compared by means of the paired t-test, whereas those obtained in microhardness testing were compared by ANOVA with Bonferroni correction. There was no statistically significant difference between brands in either trial. Conclusion: Composition analysis revealed that all of the artificial teeth analyzed contain carbon and oxygen. Trilux and Soluut PX brand teeth also contain silicon; however, the presence of filler particles did not result in increased resistance.

scholarly journals Microleakage under Ceramic and Metallic Brackets Bonded with Resin-Modified Glass Ionomer

2009 ◽  
Vol 79 (1) ◽  
pp. 138-143 ◽  
Author(s):  
Sabri Ilhan Ramoglu ◽  
Tancan Uysal ◽  
Mustafa Ulker ◽  
Huseyin Ertas
Keyword(s):  
Glass Ionomer ◽  
Bonferroni Correction ◽  
Adhesive Systems ◽  
Dye Penetration ◽  
Group 4 ◽  
System A ◽  
Significant Difference ◽  
Resin Modified Glass Ionomer ◽  
Ceramic Brackets ◽  
Group 3

Abstract Objective: To test the null hypothesis that there is no significant difference between the microleakage of adhesive interferences at the occlusal and gingival margins of both ceramic and metallic brackets bonded with light-cured resin-modified glass ionomer and a conventional adhesive. Materials and Methods: Sixty freshly extracted human maxillary premolar teeth were randomly divided into four groups of 15 teeth each. Metal and ceramic brackets were bonded to groups 1 and 2 with resin-modified glass ionomer adhesive (RMGIA). Metal and ceramic brackets were bonded to group 3 and group 4 with a conventional adhesive (CA) system. A dye-penetration method was used for microleakage evaluation. Microleakage from the occlusal and gingival margins was determined by a stereomicroscope for the enamel-adhesive and bracket-adhesive interfaces. Statistical analysis was performed using the Kruskal-Wallis test and the Mann-Whitney U-test with a Bonferroni correction. Results: The gingival side of all groups exhibited higher microleakage scores compared with the occlusal side for both adhesive interfaces. All bracket and adhesive combinations displayed statistically significant differences in microleakage between the enamel-adhesive and adhesive-bracket interfaces at the occlusal and gingival sides of the brackets (P &lt; .001). When the adhesive systems were compared, the RMGIA showed more microleakage than the CA between the different interfaces. Conclusions: The hypothesis is rejected. RMGIA results in more microleakage between enamel-adhesive interfaces.

scholarly journals An Evaluation of Electromagnetic Exposure While Using Ultra-High Frequency Radiofrequency Identification (UHF RFID) Guns

Sensors ◽  
2019 ◽  
Vol 20 (1) ◽  
pp. 202 ◽  
Author(s):  
Patryk Zradziński ◽  
Jolanta Karpowicz ◽  
Krzysztof Gryz ◽  
Victoria Ramos
Keyword(s):  
High Frequency ◽  
General Public ◽  
Environmental Influence ◽  
Uhf Rfid ◽  
Exposure Limits ◽  
Case Scenario ◽  
Worst Case ◽  
Ultra High Frequency ◽  
Close Proximity ◽  
Radiofrequency Identification

The aim is to evaluate specific absorption rate (SAR) values from exposure near handheld ultra-high frequency radiofrequency identification readers (UHF RFID guns—small electronic devices, or even portable computers with relevant accessories—emitting up to several watts of electromagnetic field (EMF) to search for RFID sensors (tags) attached to marked objects), in order to test the hypothesis that they have an insignificant environmental influence. Simulations of SAR in adult male and female models in seven exposure scenarios (gun near the head, arm, chest, hip/thigh of the operator searching for tags, or near to the chest and arm of the scanned person or a bystander). The results showed EMF exposure compliant with SAR limits for general public exposure (ICNIRP/European Recommendation 1999/519/EC) at emissions up to 1 W (reading range 3.5–11 m, depending on tag sensitivity). In the worst-case scenario, guns with a reading range exceeding 5 m (>2 W emission) may cause an SAR exceeding the general public limits in the palm of the user and the torso of the user, a bystander, or a scanned person; occupational exposure limits may be exceeded when emission >5 W. Users of electronic medical implants and pregnant women should be treated as individuals at particular risk in close proximity to guns, even at emissions of 1 W. Only UHF RFID guns emitting below 1 W may be considered as environmentally insignificant EMF sources.

Anterior-Posterior (AP) Calcaneal Profile View: A Novel Radiographic Image to Assess Varus Malalignment

2020 ◽  
Vol 41 (10) ◽  
pp. 1249-1255
Author(s):  
John Y. Kwon ◽  
Bruno Moura ◽  
Tyler Gonzalez ◽  
Christopher P. Miller ◽  
Jorge Briceno
Keyword(s):  
Pairwise Comparison ◽  
Bonferroni Correction ◽  
Varus Malalignment ◽  
Profile View ◽  
Varus Angulation ◽  
Significant Difference ◽  
The Mean ◽  
Calcaneus Fractures ◽  
Axial View ◽  
Anterior Posterior

Background: Assessing and correcting malalignment is important when treating calcaneus fractures. The Harris axial view is commonly utilized to assess varus deformity but may be inherently inaccurate due to its tangential nature. The anterior-posterior (AP) calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. Methods: Five nonpaired ankle cadaveric specimens were used in this investigation. Oblique osteotomies were created in relation to the long axis, and varus deformities were produced by inserting solid radiolucent wedges into the osteotomies to create models of 10, 20, and 30 degrees of angulation of the calcaneal tuberosity. Specimens were imaged using both the Harris axial view and the AP calcaneal profile view. Results: For cadavers with 10 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 10.9 ± 4.8 (range, 5.5-16.0) degrees and 13.0 ± 5.5 (range, 7.3-20.9) degrees, respectively. For cadavers with 20 degrees of actual varus angulation, the mean Harris view angle and the AP calcaneal profile view angle were 11.5 ± 2 (range, 8.2-13.6) degrees and 18.1 ± 4.8 (range, 11.7-23.5) degrees, respectively ( P = .005). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle ( P = .012) and actual angulation ( P = .011). For cadavers with 30 degrees of actual varus angulation, the mean Harris axial view angle and the AP calcaneal profile view angle were 18.3 ± 4.3 (range, 13.3-23.6) degrees and 28.3 ± 2.9 (range, 24.4-31.1) degrees, respectively ( P < .001). On pairwise comparison with Bonferroni correction, there was a significant difference between the Harris axial view angle and both the AP calcaneal profile view angle ( P = .001) and actual angulation ( P < .001). There was no significant difference between the AP calcaneal profile view angle and actual angulation ( P > .999). Conclusion: The AP calcaneal profile view is a novel radiographic view that is easily obtained with demonstrated increased accuracy for assessing calcaneal axial alignment. While both views demonstrated similar measurement error for lesser degrees of varus malalignment, the AP calcaneal profile view demonstrated more accurate measurement of increasing heel varus compared with the Harris view. Clinical Relevance: The AP calcaneal profile view could be used in addition to other radiographic views when treating displaced, intra-articular calcaneus fractures to help optimize correction of hindfoot alignment.

Survival rate of self-tapping implants for bone-anchored hearing aids

2006 ◽  
Vol 121 (2) ◽  
pp. 101-104 ◽  
Author(s):  
A Tjellström ◽  
G Granström ◽  
M Odersjö
Keyword(s):  
Hearing Aids ◽  
High Frequency ◽  
Operating Time ◽  
The Self ◽  
Heavy Smoker ◽  
Exact Test ◽  
Time Period ◽  
Significant Difference ◽  
Bone Anchored Hearing Aid

Objective: The purpose of this study was to investigate whether a new self-tapping implant for a bone-anchored hearing aid (BAHA) had the same high frequency of osseointegration as previous implants requiring pre-tapping.Method: Over a three-year period, 144 consecutive implants were placed in the mastoid for BAHA and evaluated.Results: Two implants were lost; both were of the self-tapping type. One was in an 11-year-old boy, who lost his implant six weeks after surgery when the BAHA was fitted. The other was in an elderly man, a heavy smoker with diabetes. Using Fisher's exact test, there was no significant difference between the two groups (p>0.30).Conclusion: Self-tapping implants facilitate surgery and shorten operating time. Over a short follow up, we did not find any significant difference; however, it is important to follow these implants over a longer time period.

scholarly journals The effect on tumour control probability of using AXB algorithm in replacement of AAA for SBRT of hepatocellular carcinoma located at lung–liver boundary region

BJR|Open ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Michael Lok Man Cheung ◽  
Monica WK Kan ◽  
Vanessa TY Yeung ◽  
Darren MC Poon ◽  
Michael KM Kam ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Volumetric Modulated Arc Therapy ◽  
Boundary Region ◽  
Volume Data ◽  
Worst Case ◽  
Tumour Control ◽  
Tumour Control Probability ◽  
Significant Difference ◽  
Target Volumes ◽  
The Difference

Objective: To retrospectively analyze the clinical impact on stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) located at lung–liver boundary due to the use of Acuros XB algorithm (AXB) in replacement of anisotropic analytical algorithm (AAA). Methods: 23 SBRT volumetric modulated arc therapy (VMAT) plans for HCC located at lung–liver boundary were calculated using AAA and AXB respectively with the same treatment parameters. The dose–volume data of the planned target volumes (PTVs) were compared. A published tumour control probability (TCP) model was used to calculate the effect of dosimetric difference between AAA and AXB on tumour control probability. Results: For dose calculated by AXB (Dose to medium), the D95% and D98% of the PTV were on average 2.4 and 3.1% less than that calculated by AAA. For dose calculated by AXB (dose to water), the D95% and D98% of the PTV were on average 1.8%, and 2.7% less than that calculated by AAA. Up to 5% difference in D95% and 8% difference in D98% were observed in the worst cases. The significant decrease in D95% calculated by AXB compared to AAA could result in a % decrease in 2 year TCP up to 8% in the worst case (from 46.8 to 42.9%). Conclusion: The difference in dose calculated by AAA and AXB could lead to significant difference in TCP for HCC SBRT located at lung–liver boundary region. Advances in knowledge: The difference in calculated dose and tumour control probability for HCC SBRT between AAA and AXB algorithm at lung–liver boundary region was compared.

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