Head Parameters Research Articles

Wetting Behavior Driven by Surface Morphology Changes Induced by Picosecond Laser Texturing.

The laser surface texturing (LST) technique has recently been used to enhance adhesion bond strength in various coating applications and to create structures with controlled hydrophobic or superhydrophobic surfaces. The texturing processing parameters can be adjusted to tune the surface's polarity, thereby controlling the ratio between the polar and dispersed components of the surface free energy and determining its hydrophobic character. The aim of this work is to systematically select appropriate laser and scan head parameters for high-quality surface topography of metal-based materials. A correlation between texturing parameters and wetting properties was made in view of several technological applications, i.e., for the proper growth of conformal layers onto laser-textured metal surfaces. Surface analyses, carried out by scanning electron microscopy and profilometry, reveal the presence of periodic microchannels decorated with laser-induced periodic surface structures (LIPSS) in the direction parallel to the microchannels. The water contact angle varies widely from about 20° to 100°, depending on the treated material (titanium, nickel, etc.). Nowadays, reducing the wettability transition time from hydrophilicity to hydrophobicity, while also changing environmental conditions, remains a challenge. Therefore, the characteristics of environmental dust and its influence on the properties of the picosecond laser-textured surface (e.g., chemical bonding of samples) have been studied while monitoring ambient conditions.

Numerical simulation of 3D concrete printing derived from printer head and printing process

Ensuring the repeatability and stability of printing process is significant for the 3D Concrete Printing (3DCP). However, the diversity of printers often leads to unpredictable printing journeys. Hence, in this study the printer head was dimensionally characterized by three factors: channel diameter, neck height, and nozzle diameter. The effects of printer head and process parameters (travel speed, extrusion flow rate, and nozzle height) on the geometry stability and shape of printed filament were investigated with computational fluid dynamics method. The results indicated that, for printing materials without coarse aggregates, extrusion methods had a negligible impact on 3DCP process. For the printer head, the nozzle diameter dominated the geometry stability while the neck height and channel diameter had little effects. A dimensionless parameter φ was proposed to quantitatively analyze the influences of travel speed, extrusion flow rate, and nozzle diameter. The systematic mechanical analysis indicated that the geometry instability (tearing and meandering) was controlled by the φ and nozzle height. Based on the above analysis, the selection principle for printing parameters was proposed to ensure a stable and repeatable printing. The research results regarding printer heads and printing parameters can greatly promise the large-scale application of 3DCP.

Watch Your Head: Assembling Projection Heads to Save the Reliability of Federated Models

Federated learning encounters substantial challenges with heterogeneous data, leading to performance degradation and convergence issues. While considerable progress has been achieved in mitigating such an impact, the reliability aspect of federated models has been largely disregarded. In this study, we conduct extensive experiments to investigate the reliability of both generic and personalized federated models. Our exploration uncovers a significant finding: federated models exhibit unreliability when faced with heterogeneous data, demonstrating poor calibration on in-distribution test data and low uncertainty levels on out-of-distribution data. This unreliability is primarily attributed to the presence of biased projection heads, which introduce miscalibration into the federated models. Inspired by this observation, we propose the "Assembled Projection Heads" (APH) method for enhancing the reliability of federated models. By treating the existing projection head parameters as priors, APH randomly samples multiple initialized parameters of projection heads from the prior and further performs targeted fine-tuning on locally available data under varying learning rates. Such a head ensemble introduces parameter diversity into the deterministic model, eliminating the bias and producing reliable predictions via head averaging. We evaluate the effectiveness of the proposed APH method across three prominent federated benchmarks. Experimental results validate the efficacy of APH in model calibration and uncertainty estimation. Notably, APH can be seamlessly integrated into various federated approaches but only requires less than 30% additional computation cost for 100x inferences within large models.

Correlation between Structural and Functional Changes in Patients with Raised Intraocular Pressure Due to Graves' Orbitopathy.

This study explores the complication of secondary intraocular pressure (IOP) elevation and consequent glaucoma development in Graves' orbitopathy (GO), an autoimmune disorder associated with hyperthyroidism. Utilizing Octopus 900 visual field testing and optical coherence tomography (OCT), the research established correlations between functional and structural changes in optic nerve regions in patients with GO and patients with GO with elevated IOP (GO IOP) groups. A comparison with primary open-angle glaucoma (POAG) was conducted in a cohort of 182 subjects. The study identifies optic nerve head parameters that effectively differentiate changes in GO and GO IOP groups. In the GO group, the strongest correlation between structural and functional changes was observed in sector 7, while in the GO IOP group, it was in sectors 1 and 7. For POAG, correlation was found in six sectors. Elevated IOP in GO correlates with structural and functional impairments similarly to early glaucoma. Risk factors for GO-related elevated IOP included older age, longer duration of thyroid disease, and higher anti-thyroglobulin values. The study highlights the significance of regular IOP measurements, visual field assessments, and OCT examinations in GO patients. Early antiglaucoma intervention is warranted when characteristic structural and functional changes and/or risk factors are identified.

Morphological differences of the neuroretinal rim between temporally tilted and non-tilted optic discs in healthy eyes

This study aimed to compare morphological differences of the neuroretinal rim between the temporally tilted and non-tilted optic discs in healthy eyes. We prospectively enrolled participants aged 20–40 years with temporally tilted or non-tilted optic discs. The optic nerve head parameters were analyzed using spectral domain-optical coherence tomography. The angle between the Bruch’s membrane opening (BMO) plane and BMO-minimum rim width (BMO-MRW) was termed “BMO-MRW angle”. Peripapillary retinal nerve fiber layer thickness (pRNFLT) and BMO-based parameters were compared between the temporally tilted and non-tilted disc groups. As a result, 55 temporally tilted disc eyes and 38 non-tilted disc eyes were analyzed. Global pRNFLT, global BMO-MRW, and total BMO-minimum rim area (BMO-MRA) were similar between the two groups (p = 0.138, 0.161, and p = 0.410, respectively). In the sectoral analysis, temporally tilted disc group exhibited thicker BMO-MRW in the temporal sector (p = 0.032) and thinner in the nasal superior and nasal sectors (p = 0.025 and p = 0.002, respectively). Temporally tilted disc group showed larger BMO-MRA in the temporal, temporal superior, and temporal inferior sectors (p < 0.001, p < 0.001, and p < 0.016, respectively), alongside a higher BMO-MRW angle in the temporal sector and lower in the nasal superior and nasal sectors. In conclusion, the neuroretinal rim, represented by BMO-MRW and BMO-MRA, showed morphological differences between temporally tilted and non-tilted optic discs in healthy eyes. BMO-MRW and BMO-MRA showed temporalization in the same manner as pRNFLT in the temporally tilted disc eyes. The BMO-MRW angle showed that in temporally tilted disc eyes, optic nerve fibers met the BMO plane steeply in the nasal sector and gently in the temporal sector than in non-tilted disc eyes, suggesting potential stress region of optic nerve fibers in temporally tilted disc eyes.

The influence of post-COVID-19 syndrome on microcirculation of the optic nerve head among patients with primary open-angle glaucoma

BACKGROUND: Glaucoma is one of the leading causes of blindness in the world. This is a multifactorial ophthalmopathology, which also results from impaired microcirculation in the optic nerve. One of the diseases affecting ocular blood flow is acute coronavirus infection (COVID-19). AIM: The aim of this study is the assessment of blood flow parameters of the optic nerve head in patients with primary open-angle glaucoma (POAG) against the background of post-COVID-19 syndrome using laser speckle flowgraphy. MATERIALS AND METHODS: The study included 40 patients with advanced stage primary open-angle glaucoma who had COVID-19 within the previous 3 months. Patients were divided into 2 subgroups depending on the severity of the disease. The comparison group consisted of 20 individuals with an advanced stage of primary open-angle glaucoma who did not have COVID-19. All subjects were over 60 years old and had normal blood pressure parameters. Optic nerve head blood flow was measured using the LSFG-NAVI device (Japan) and assessed by LSFG Analyzer software. MBR parameters (MA, MV and MT), as well as pulse wave indicators (Skew, BOS, BOT, RR, FR, FAI, ATI and RI) were analyzed. RESULTS: The most significant decrease was found for the MV and MT parameters, reflecting the blood flow in large vessels and the microvasculature of the optic disc. MV decrease by 20%, MT — by 23%, MA — by 16% were noted, as well as pulse wave parameter changes, in patients with an advanced stage of primary open-angle glaucoma, post-COVID syndrome after moderate COVID-19 compared with patients with an advanced stage of primary open-angle glaucoma who did not have COVID-19 (p ≤ 0.05). CONCLUSIONS: Laser speckle flowgraphy allows rapid and effective assessment of ocular blood flow. Parameters estimated at the examination may be considered as new biomarkers for the detection and evaluation of vascular diseases.

The Distribution of Boars Spermatozoa in Morphometrically Distinct Subpopulations after In Vitro Exposure to Radiofrequency Electromagnetic Radiation at 2500 MHz and Their Motility.

Anthropogenic radiofrequency electromagnetic radiation (RF-EMR) from wireless technologies has increased dramatically. The boar semen used for artificial insemination is essential in sustaining the pig industry, and additionally it is also exposed to the effects of the RF-EMR of wireless technologies. Furthermore, there are no data on the effects of RF-EMR on semen quality, and this is the first analysis of sperm's morphometric parameters for assessing the effect of RF-EMR on the spermatozoa subpopulations of boars. This study investigated the effect of RF-EMR on in vitro exposed breeding boar semen spermatozoa motility and the proportions of spermatozoa subpopulations according to their morphometric head and tail parameters. The semen samples of 12 boars were divided into control and experimental groups. The samples in the experimental group were exposed in a gigahertz transverse electromagnetic chamber at a frequency of 2500 MHz (the frequency band used in 5G technology) and an electric field strength of 10 Vm-1 for two hours. After exposure, the spermatozoa motility was evaluated for both groups. A morphometric analysis of the semen smears was performed using SFORM software (Version 1.0; VAMS, Zagreb, Croatia). The progressive spermatozoa motility was significantly reduced in the experimental group (74.7% vs. 85.7%). PC analysis and cluster analysis revealed two spermatozoa subpopulations: S1, spermatozoa with a more regular head shape and a smaller midpiece outline, and S2, spermatozoa with a more elongated head shape and a larger midpiece outline. The experimental semen samples had a greater proportion of the S1 spermatozoa subpopulation (68.2% vs. 64.4%). The effect of RF-EMR at 2500 MHz on the in vitro exposed boar semen resulted in decreased progressive spermatozoa motility and a lower proportion of the spermatozoa subpopulation with a higher fertilizing potential.

Research on aircraft skin rivet detection technology based on the normal vector-density clustering algorithm.

Riveting quality is crucial to an aircraft's overall aerodynamic performance and fatigue life. In order to effectively extract the point cloud of rivet heads and analyze the quality of riveting, this paper proposes a rivet flushness detection method based on the normal vector-density clustering algorithm. First, initial point cloud data sampling is based on normal vectors. Then, the density clustering algorithm is employed to cluster and extract the point cloud of rivet heads. Subsequently, the obtained point cloud of rivet heads is subjected to the random sample consensus algorithm for fitting the contour and obtaining the model parameters of the rivet head. The paper introduces a quality detection metric to describe the flushness of the rivet head. Finally, the proposed method is applied to analyze the skin and theoretical model point cloud data of rivets. The results demonstrate that the proposed method yields small errors and high accuracy compared to theoretical values. The method is further employed for quality detection and analysis of rivet flushness in practical aircraft engineering. A visualization system for rivet flushness quality detection is developed to represent the results visually. This system enhances the intuitive identification of rivet detection outcomes. Therefore, the proposed method holds significant engineering application value in rivet flushness detection.

The problem of safe operation of chimney systems in densely populated developments

The phenomena of backdraft in chimneys due to meteorological conditions and geometrical parameters of the chimney head in the area of adjacent buildings are fundamentally considered. For the purpose of in-depth analysis of the backdraft phenomena, the meteorological parameters of atmospheric pressure and turbulence were calculated, and the wind speed was determined under operational and extreme conditions of chimney systems. Wind has a role to impact, and its consequences must be assessed to provide the required safety level of chimney systems. The technical conflict between National Norms and European Standards regarding the interpretation and definition of the "wind resistance zone" is considered separately, where the European approach has more mathematical approach. It is proposed to consider and analyse this issue according to more modern approach, using CFD computational fluid dynamic modelling and specialised software for thermal and aerodynamic calculations of chimneys, which makes it possible to assess the functional ability of a chimney, both in terms of design features and wind exposure. This approach has the advantage that the analysis is carried out locally, specifically for an individual chimney, which avoids random or template results. In other words, the interaction of the "atmosphere-chimney-room" system is considered. The ANSYS CFX-Post module analyses the formation of backdrafts for different wind speeds with the same geometric parameters of the chimney head, characterised by the speed changes of flue gas movement, static pressure, temperature field, and the formation of a flue gas plume in the atmosphere. The following factors have been identified in the modelling of the chimney functioning: the use of secondary air through the bypass hole, the temperature of the outside air is taken to calculate the minimum draft 288.15 K, the temperature of flue gases is 345.95 K. The obtained results of CFD computational modelling studies provide the motivation for the development of innovative and effective approaches to eliminate dangerous backdraft phenomena in chimneys.

Optic Nerve Head and Retinal Nerve Fiber Layer Analysis in Emmetropic Malay Children.

The study aims to investigate the normal reference values for optic nerve head (ONH) and retinal nerve fiber layer (RNFL) parameters in emmetropic Malay children, utilizing measurements obtained through Cirrus SD-OCT (Carl Zeiss Meditec, Dublin, CA). A cross-sectional study was conducted on 95 Malay children, aged between seven and 17 years, with no ocular abnormalities. It was held at Hospital Universiti Sains Malaysia, Malaysia, from January 2014 to December 2015. All children underwent a full ocular examination, including refraction and calculation of axial length. ONH and retinal nerve fiber layer thickness (RNFLT) parameters were measured using the Cirrus SD-OCT machine. One eye of each subject was selected randomly for study. The associations between the parameters and the effect of age, gender,axial length, and spherical equivalent (SE) on the measurements were statistically validated. Ninety-five children were involved in the study, with 65 females (68.4%) and 30 males (31.6%). The mean age was 10.6 (2.82) years, the mean intraocular pressure (IOP) was 14.8 (2.81) mmHg, the mean SE-refraction was 0.12 (0.28) diopters, and the mean axial length was 23.03 (0.76) mm. The mean disc area, rim area, and cup volume were 2.32 (0.40) mm2, 1.53 (0.33) mm2, and 0.204 (0.16) mm3, respectively. The average cup-to-disc ratio (SD) (CDR) and the vertical CDR were 0.55 (0.13) and 0.50(0.14). Mean (SD) RNFLT was 102.08 (11.08) μm for all patients. There was a strong positive correlation between the average, superior, and inferior RNFLT with the optical disc area. The rim area and the average, superior, inferior, and nasal RNFLT alsoshowed a significant correlation. The inferiorRNFLT was negatively correlated with the average CDR. There was also a major influence of gender on the disc area. There were no major age, axial length, and SE influences on the measurements. This study provided normative information for ONH and RNFLT parameters in emmetropic Malay children. It was observed that emmetropic Malay males exhibited a significantly larger optical disc area. The increase in RNFLT is correlated with a significant increase in disc and rim areas.

Clinical Characteristics and Associated Factors to the Development of Glaucoma in Eyes With Myopic Optic Neuropathy

PurposeTo observe the development of glaucoma in myopic eyes with and without myopic optic neuropathy (MON) and analyze associated factors to the development of typical glaucomatous damage. DesignA prospective, observational, cohort study MethodsA total of 233 myopic eyes with no definite evidence of glaucomatous damage were included in the study. Myopic patients without any retinal nerve fiber layer (RNFL) or visual field (VF) abnormalities were classified as myopic eyes without MON. Myopic patients with decreased RNFL at the superonasal (SN) or nasal area, and with corresponding VF defects either in the temporal or inferotemporal (IT) region, which is different from glaucomatous damage, were classified as myopic eyes with MON. Myopic eyes that developed glaucoma were defined by the presence of glaucomatous VF in the SN region including defects in Bjerrum area, or a new localized RNFL defect in the IT region on red-free photography or RNFL OCT. Disc morphological features and optic nerve head (ONH) parameters of two groups were compared. Hazard ratios for the association between baseline factors and conversion to glaucoma were obtained using Cox regression analysis. ResultsMean follow-up period was 11.66 ± 2.86 years. Myopic eyes with MON had a thinner average peripapillary RNFL thickness (P < 0.001), worse MD of the VF (P = 0.031), a higher percentage of IT VF defects (P < 0.001), smaller torsion degree (P = 0.047), and greater LCD (P = 0.022). Myopic eyes with MON who developed glaucoma had a thinner average peripapillary RNFL thickness (P = 0.009), greater PPA area (P = 0.049), greater LCD (P < 0.001), and thinner LCT (P < 0.001). Thinner baseline temporal RNFL thickness (HR, 0.956; 95% CI, 0.928–0.986; P = 0.004), greater baseline LCD (HR, 1.003; 95% CI, 1.000–1.005; P = 0.022), and greater PPA area (HR, 1.000; 95% CI, 1.000–1.003; P = 0.050) were significantly associated factors with glaucoma development in the Cox regression analysis. ConclusionMyopic eyes with MON have a greater risk to develop glaucoma compared to myopic eyes without MON. Myopic eyes with MON had larger PPA area, greater LCD, and thinner temporal peripapillary RNFL, indicating that accompanying structural weakness due to myopia, especially at the temporal side of the optic nerve head and the peripapillary sclera, increases the risk of glaucoma in myopic eyes with MON.

The predictive value of parameters of optic disk in evaluating the progression of myopia

Aims/Purpose: To analyse the parameters of the optic nerve head (ONH) as markers of the progression of myopia with the usage of optical coherence tomography (OCT).Methods: 72 patients (144 eyes) aged 9–57 years with myopia were investigated. The standard OCT parameters of the ONH, the ovality index (OI), the zone of parapapillary atrophy (PPA), location of the lamina cribrosa (LC) of the sclera and the trunk of the central retinal vessels (CRV) were evaluated. Data was statistically approved.Results: A positive correlation between the axial length (AL) and the optic disc cup area, its horizontal and vertical diameters was found. Whilst the volume and the depth of the optic disc cup increased till the AL reached a certain critical value (26.3 mm) with subsequent reduction. An inverse correlation between the AL and the neuroretinal rim area, volume and rim/disc ratio was revealed. These changes in the ONH can be explained by scleral remodelling during elongation of the eye. Formation of γ‐zone PPA and an increase in the β‐zone PPA was accompanied by the tendency of thinning of the retinal nerve fibre layer (RNFL) in the inferior, nasal‐superior and superior sectors of the ONH. In 27.63% cases tilted optic discs were noted, of which 61.90% were vertically and 38.1% ‐ horizontally tilted. The direction of the tilt was determined by the location of the PPA zone with a tendency to thinning of the RNFL in the same sectors. A positive correlation between the AL of eye and the location of the LC of sclera was found. In 29.17% the superficial location of the LC was determined. In 54.17% elongation was accompanied by displacement of the trunk of the CRV on ONH in the nasal ‐ 71.79%, or in the superior‐nasal direction ‐ 28.21%.Conclusions: The revealed changes of optic disc cup, neuroretinal rim and the parapapillary zones; a superficial displacement of LC of sclera and ‘nasalization’ of the trunk of CRV; a decrease in the OI with growth in the AL; relationships of the PPA zone with a tendency to thinning of the RNFL and direction of the tilt can be useful as OCT markers in interpreting normative data in patients with myopia, predicting its progression, and also in differential diagnosis with glaucomatous optic neuropathy.

Evaluation of Peripapillary Choroidal Thickness, Retinal Nerve Fiber Layer, and Optic Nerve Head Parameters in Patients with Multiple Sclerosis.

The objectives of the study are to assess the peripapillary choroidal thickness (PPCT), retinal nerve fiber layer (RNFL), and optic nerve head (ONH) parameters in multiple sclerosis (MS) patients compared to healthy subjects. One hundred and twenty-eight eyes from 64 patients were included in this cross-sectional study. Eighty-two eyes of 41 MS patients and 46 eyes of 23 healthy subjects were examined. PPCT and RNFL were measured using spectral-domain optical coherence tomography (OCT). PPCT was measured from the four quadrants around the optic disc at a distance of 1 mm (PPCT-1) and 2 mm (PPCT-2) from the edge of the ONH and the beginning of the retinal pigment epithelium. ONH parameters were measured with Heidelberg retinal tomography (HRT-3). Disease duration, the number of episodes, MS subtypes, and Expanded Disability Status Scale (EDSS) scores were recorded. The RNFL measurements and the mean PPCT-1 and PPCT-2 were significantly lower in MS patients compared to healthy individuals. PPCT-1 and PPCT-2 were measured as the thickest in the temporal quadrant, followed by the superior, nasal, and inferior quadrants, respectively, in both groups. When the ONH parameters were evaluated, cup/disc area ratio, cup area, and cup volume values were significantly higher, whereas optic rim volume and rim area values were significantly lower in MS patients compared to healthy subjects (p<0.05). We observed significant changes in RNFL and ONH parameters of MS patients in parallel with disease severity determined by EDSS scores and the presence of optic neuritis. There were significant changes in RNFL thickness, PPCT, and ONH parameters when MS patients were compared with healthy subjects. Assessment of RNFL and PPCT with OCT and ONH with HRT-3 may be useful in the follow-up of MS patients.

Development of Small Hydroelectric Power Plant Maintenance Costs using Chaos Embedded Adaptive Particle Swarm Optimization

In this study, a new equation model is proposed to improve the maintenance costs of Small Scale Hydroelectric Power Plants (SHPP). The proposed equation model consists of 4 terms and 7 parameters using the Chaos Embedded Adaptive Particle Swarm Optimization (CEAPSO). The MATLAB program was used to calculate the parameters in the proposed equation model. In this study, the main error value for 14 maintenance items required for a SHPP is calculated as 17.4819%. The maintenance cost of a SHPP to be installed in this way can be predicted with high accuracy using the proposed equation model. In the study, the sensitivity analysis of the proposed equation model is also performed, and maintenance cost changes are expressed in different parameter values. In the study, corrected data from 8 SHPP in India are used. These data cover the maintenance costs of all components for the years 2015-2016. In the study, unlike the literature, the flow parameter is added to the power and head parameters. In this way, a more sensitive equation model is developed for SHPP data. In addition, realistic results are obtained by applying constraints to the parameters. Considering the 14 different maintenance cost parameters examined in the study, a correlation model is proposed to give better results than the literature for other maintenance costs except the power channel and penstock cost.

Influence of Positive Guide Vane Geometric Parameters on the Head-Flow Curve of the Multistage Pump as Turbine

In order to reduce the impact of production changes on the performances of pumps as turbines (PATs) in the process industry, it is imperative to lessen head variations at different mass flow rates. This study established a relationship equation between theoretical head and geometric parameters for multistage PATs. The influence of these parameters on the flatness of the head-flow (H-Q) curve was determined through derivation methods. The original PAT was a two-stage pump, and 12 PAT models were designed by modifying the geometric parameters of the positive guide vanes. Fluent software was employed for numerical simulations. The study found that numerical calculations aligned well with theoretical derivations for the flat H-Q curve. Considering the geometric variations in the positive guide vane, increasing the outlet placement angle, blade number, and throat area or decreasing the base circle diameter was able to flatten the H-Q curve effectively; at the best efficiency point, the throat area had the most significant impact on a slope, followed by the outlet placement angle, blade number, and base circle diameter, respectively. The individual contributions to reducing the slope were 0.53, 0.24, 0.1, and 0.09. In terms of the best efficiency point (BEP) of PATs, increasing the throat area appropriately was able to improve the BEP of the PAT by around 1.65% and shifted its BEP towards higher flow rates. However, in other cases, the BEPs all decreased. Increasing the outlet placement angle of the positive guide vane by 3° led to the BEP being reduced by 0.79%. When the number of positive guide vane blades was increased from 8 to 10, the BEP decreased by 1.24%. When the diameter of the base circle of the positive guide vane was decreased, the BEP of the turbine decreased by 0.06%. This study provides theoretical support and can serve as a reference for the design of multistage hydraulic turbines with flatter H-Q curves.

Determining the effects of AR/VR HMD design parameters (mass and inertia) on cervical spine joint torques

This study aimed to determine gravitational and dynamic torques and muscle activity of the neck across a series of design parameters of head mounted displays (mass, center of mass, and counterweights) associated with virtual and augmented reality (VR/AR). Twenty young adult participants completed five movement types (Slow and Fast Flexion/Extension and Rotation, and Search) while wearing a custom-designed prototype headset that varied the three design parameters: display mass (0, 200, 500, and 750 g), distance of the display's center of mass in front of the eyes (approximately 1, 3, and 5 cm anteriorly), and counterweights of 0, 166, 332, and 500 g to balance the display mass of 500 g at 7 cm. Inverse dynamics of a link segment model of the head and headset provided estimates of the torques about the joint between the skull and the occiput-first cervical vertebrae (OC1) and joint between the C7 and T1 vertebrae (C7). Surface electromyography (EMG) measured bilateral muscle activity of the splenius and upper trapezius muscles. Adding 750 g of display mass nearly doubled root mean square joint torques across all movement types. Increasing the distance of the display mass in front of the eyes by 4 cm increased torques about OC1 for the Slow and Fast Rotation and Search movements by approximately 20%. Adding a counterweight decreased torques about OC1 during the rotation and search tasks but did not decrease the torques experienced in the lower cervical spine (C7). For the flexion/extension axis, the magnitude of the dynamic torque component was 20% or less of the total torque experienced whereas for the rotation axis the magnitude of the dynamic torque component was greater than 50% of the total torque. Surface EMG root mean square values significantly varied across movement types with the fast rotation having the largest values; however, they did not vary significantly across the headset configurations.

Effect of Bergmeister papilla on disc parameters in spectral domain optical coherence tomography

ObjectivesTo investigate the morphological characteristics of Bergmeister papilla (BMP), a persistent hyaloid remnant tissue, and its effects on the measurements and repeatability of spectral-domain optical coherence tomography (OCT).Subjects/MethodsThe subjects of this prospective cross-sectional study including 83 patients with BMP and 76 unaffected individuals, all had open-angle structures. Images, including a 5-line raster and three consecutive optic disc cube scans centred on the optic disc, were acquired using the Cirrus high-definition OCT. BMP’s structural characteristics were classified based on the raster scan images, and repeatability of acquiring optic nerve head and retinal nerve fibre layer parameters acquisition was analysed by calculating the test-retest standard deviation (Sw), coefficient of variance (CV), and intraclass correlation coefficient.ResultsBMPs (n = 83) were categorised into lifting edge (LE) type (63.9%, n = 53), which partially covers the edge of the optic nerve head, and covering disc (CD) type (36.1%, n = 30), which completely covers the cupping area like a cap. The average cup-to-disc ratio (0.58 ± 0.21), vertical cup-to-disc ratio (0.55 ± 0.21), and cup volume (0.22 ± 0.22) of the CD type were lower than those of the LE type (0.66 ± 0.13, 0.64 ± 0.13, and 0.4 ± 0.27, respectively; all P < 0.05). Tolerability indices for repeatability of cup volume (Sw = 0.40 and CV = 0.36) and inferonasal (4 o’clock) retinal nerve fibre layer (Sw = 0.27 and CV = 0.25) in LE-type BMPs exceeded the cut-off value (0.22) and demonstrated stronger correlation with BMP location than that of the controls.ConclusionCaution should be exercised when interpreting OCT findings in eyes with BMP, as BMP can introduce a pitfall in OCT imaging.

Особенности диагностики глаукомы на миопических глазах в отдаленные сроки после кераторефракционной хирургии (клинический случай)

Purpose. Demonstration of a clinical case of diagnosis and dynamic observation of glaucoma in a patient after LASIK. Material and methods. Patient A., 58 years old. Complaints about decreasing in vision of the right eye into the distance during the last year. In 2004, LASIK was performed for moderate myopia with astigmatism. In 2018, for the first time, asymmetry of the parameters of the optic nerve head (the ratio of the maximum excavation size to the diameter of the disk (E/D)) was revealed for the first time: up to 0.7 in the right eye; on the left eye – up to 0.5. At the same time, the level of intraocular pressure (IOP) according to Maklakov was 22 mm Hg. Installations of prostaglandin analogues (APG) (0.005% solution of latanoprost) once are recommended. In subsequent years, the patient was on the «D» register at the place of residence, the level of IOP according to Maklakov varied from 18 to 20 mm Hg. After 4 years, the level of IOP according to Maklakov (on the previous hypotensive regimen): OD – 18 mm Hg; OS – 21 mm Hg. Ophthalmoscopically OD: E/D – 0.85–0.9; on OS: E/D – 0.9 with a breakthrough of the neuroretinal rim from below. SAP: OD – with absolute scotoma in the Bjerrum’s zone 5–15° from the fixation point, OS – blind spot expansion. Based on this, the diagnosis was formulated: primary open-angle glaucoma III A of the right eye, II A of the left eye. Results. Selective laser trabeculoplasty was performed. But due to the lack of complete stabilization of the IOP level, the hypotensive regimen was strengthened in the form of installations of APG and alpha-agonists. Despite this, the progression of glaucoma optic neuropathy was noted, and a decision was made to perform antiglaucoma surgery. Conclusion. Despite Maklakov’s IOP levels within the average statistical norm, in patients after LASIK, it is important to assess carefully the condition of the structures of the optic nerve head. Keywords: keratorefractive operations, myopia, glaucoma, ophthalmotonometry

Параметры диска зрительного нерва как маркеры прогрессирования близорукости

Параметры диска зрительного нерва как маркеры прогрессирования близорукости

The race that never slows: Otolaryngology - Head and Neck Surgery residency applicant parameters over time.

There has been an increasing number of Canadian medical graduates who have gone unmatched in the residency selection process. Medical students have been engaging in extracurricular activities outside the formal curriculum which may help to distinguish themselves from their peers in the selection process. To understand how competitiveness in residency selection shapes applicant demographic characteristics and behaviours, this study set out to explore the demographic characteristics and prevalence of reported extra-curricular activities by applicants to Canadian Otolaryngology - Head & Neck Surgery (OTL-HNS) residency across time. A retrospective, descriptive study reviewed specific sections of the curriculum vitae (CV) of applicants to OTL-HNS programs in Canada. These sections were self-reported, and included research productivity, involvement in volunteer and leadership activities, membership in associations, and honours or awards granted. Data was quantified and analyzed descriptively. Between 2013 to 2017, a total of 267 applicants reported a median of 12.6 research publications, 9.6 volunteer activities, six leadership activities, six association memberships and 9.8 honours/awards. Applicants were younger over time, with proportions of applicants over 30 years old decreasing from 56% in 2013 to 9% in 2017. Applicants to Canadian OTL-HNS residency programs are reporting consistently high numbers of extracurricular activities and were of increasingly younger ages. Medical students are investing significant time and energy to pursue these activities which are above and beyond the formal curriculum, possibly contributing to decreased diversity in applicants for competitive residencies, increasing the likelihood of misrepresentation in residency applications, and likely contributing to medical student burnout.