Absolute Thickness Research Articles

Influence of peak exercise-induced blood pressure on basal to apical myocardial wall thickness in elite athletes: a sex-specific CMR study

Abstract Background Understanding the sex-specific physiological remodelling response of the myocardial walls to peak exercise-induced blood pressure (SBPpeak) is essential for distinguishing healthy adaptation from pathological remodelling in athletes. Purpose We investigated how SBPpeak relates to myocardial wall thickness measured using cardiac magnetic resonance imaging (CMR) in elite athletes. Methods Cross-sectional analysis of healthy elite athletes included in the ELITE study who underwent both cardiopulmonary exercise testing (CPET) and CMR. Imaging software’s built-in AI option determined average end-diastolic wall thicknesses of all sixteen AHA-defined segments on short-axis cine images with four-chamber long-axis reference. Our primary metrics of interest were Spearman's correlations between SBPpeak and left ventricular mass indexed to body surface area (LVM/BSA), as well as average wall thickness across the sixteen myocardial segments, stratified by sex and endurance/non-endurance sports status. Secondary analyses involved regression models to evaluate the influence of SBPpeak on myocardial wall thickness, adjusting for sex, body size, CPET variables and sport type. Results In 75 athletes (median age: 24; 71% female; 61% engaged in endurance sports), CPET and CMR were performed within a median interval of 5 months [interquartile range: 1-13 months]. SBPpeak was similar in female and male athletes (170 [160-180] vs. 174 [169-184] mmHg, p=0.121, respectively) and in endurance and non-endurance athletes (both 170 [160-180] mmHg, p=0.625). Female elite athletes showed weak to moderate positive correlations between SBPpeak and the majority of basal and mid-ventricular AHA segments (rho = 0.27 – 0.48, Figure). This was most pronounced in the mid-ventricular anterolateral segment (AHA06: rho = 0.48, p<0.001). LVM/BSA in females was positively correlated with SBPpeak (rho = 0.31, p=0.025). Male elite athletes demonstrated greater absolute wall thickness across all AHA segments compared to females, however, there was a moderate correlation with SBPpeak exclusive to the basal anterior segment (AHA01: rho = 0.48, p=0.028). Backward stepwise multivariate regression analyses (Table) revealed SBPpeak as an independent predictor of the thickness of all basal AHA segments except for the basal inferoseptal segment (AHA03), and the mid-anterior and anterolateral segments. Associationswere maintained after adjustment for maximum wattage, body surface area, and sex, with type of sports consistently excluded from the models. Conclusion In the extreme phenotypes of elite athletes, SBPpeak correlates especially with basal myocardial thickness, independent of sex, BSA and maximum work rate influences. We found stronger associations between SBPpeak and myocardial adaptation in female athletes. These findings suggest a paramount role of exercise-induced blood pressure on basal myocardial remodelling surpassing the effect of sports type.Figure:segmental polar plot (heat map)Table:GAM regression models

Absolute wall thickness measurement of conducting plates using pulsed eddy currents

Absolute wall thickness measurement of conducting plates using pulsed eddy currents

Absolute thickness field measurement on curved axisymmetric thin free films with monochromatic light

The thickness of thin films is a key parameter to understand their thinning dynamics and stability. Thickness measurements are commonly performed using interferometry. White light illumination allows us to measure the absolute thickness, but is limited to small thicknesses (<2μm) or is restricted to a point with a spectrometer. Monochromatic light gives access to a broader range of thicknesses but solely in a relative manner unless a reference thickness is known. These methods are extensively used to quantify the thickness profiles of flat soap films. In contrast, they are applied to curved interfaces (bubbles) only in a few specific cases, mainly due to the complexity arising from the curvature as the optical path depends on the position. In this paper, we elucidate the influence of the curvature and show that it can be used to measure the entire and absolute thickness profiles using monochromatic light. We demonstrate the validity of the method on soap bubbles, antibubbles, and catenoid soap films. This cost-effective technique is adapted to quantitatively study the thin film dynamics in these geometries.

Fluorescence-Based Calibration Model for In-Situ Measurement of Micro-scaled Lubricant Thickness Distribution at Indentation Interface

This study proposes a model for the measurement of microscale liquid film thickness distribution using fluorescence signals. The interfacial conditions between the tool and the workpiece in mechanical machining are important for understanding these phenomena and mechanisms. In this study, indentation tests with transparent tools were used to observe interfaces; however, it was challenging to obtain the signal from a thin fluorescent liquid film on smooth and steeply inclined surfaces. Therefore, fluorescence-based measurement, such as laser-induced fluorescence, was employed. To measure the absolute thickness of the thin fluorescent film, calibration of the measurement system is necessary. Therefore, a theoretical model was proposed considering the multiple reflections of excitation light and fluorescence at the inclined surface between the indenter and workpiece. By measuring the profile of the surface topography of the indented workpiece and comparing the results with those measured by a surface profiler, the validity of the proposed calibration method and the performance of this measurement system were demonstrated. The measured surface profiles, including scratches of 2–4 µm, were in good agreement, demonstrating the validity of the proposed method.

Bark thickness and related parameters of tree species along an elevation transect leading to treeline in Central Himalaya.

Since treelines are generally fire-free, the trees growing there are expected to have thin bark, unless adaptation to other factors than fire results in the selection of a thick bark. Related to this is also higher proportional investment in inner bark in such an environment of infrequent fire. This study has considered stem bark thickness both in absolute and relative terms and also in the frame of the composition of outer and inner bark components of 20 tree species along an elevation transect (2100-3300m) in high ranges of the Central Himalaya leading to treelines. The study species varied from 2.1 to 16.2mm for total bark thickness and from 1.2 to 18.85% for relative bark thickness. The average absolute total bark thickness across the tree species decreased with elevation from forest to treeline, both when trees of all diameters (10.2 ± 0.84mm for forest and 6.9 ± 1.79mm for treeline) and those of the same stem diameter range (18-20m) were compared (9.10 ± 1.30mm for forest species and 6.38 ± 1.31mm for treeline species). Nevertheless, the treeline bark thickness was similar to those of several forest communities considered to have comparatively thick bark. Like many other biological structures, bark carries out multiple functions; therefore, its thickness could be affected by more than one environmental factor. We suggest that the requirement of mechanical resistance to the snowfall, rainstorms, wind and adaptation to a high sunlight and UV radiations or storage of water, and non-structural carbohydrates could affect total, outer and inner bark thickness. Studies on these aspects in similar ecosystems may help understand the multi-functional attributes of the bark. For trees of comparable sizes (trees with 18-20cm diameter at breast height) treeline species also had lower relative bark thickness (< 6%) than trees of forest below it (> 7%). The median proportion of inner bark of the total bark (70.5%) for our 20 species was more than that for savannas (~ 50%), exposed to frequent fire regime and similar to those of in cool sclerophyllous forests and temperate rain forests where fire return time is > 100years. However, it was lower than the inner bark proportion reported for tropical rain forests. To conclude, in spite of a fire-free environment, the Himalayan treeline and adjoining forest species show mixed bark characters.

Features of adaptation of the skin of turkeys in industrial conditions

The skin, through its structural features, while performing its functions, participates in the formation and establishment of adaptive processes in the bird’s body in response to the influence of factors of both exogenous and endogenous origin. The purpose of this work was to study the regional and agerelated features of the histostructure of the skin of Hybrid Converter NOVO cross tur keys raised in the conditions of a poultry farm in the Tyumen region. Macroscopic and microscopic studies of the skin of turkey poults were carried out in the laboratory of the Department of Anatomy and Physiology. It has been established that turkey skin has 3 layers: epidermis, dermis and subcutaneous layer. The epidermis consists of the horny and germinal layers, the dermis of the superficial and deep layers, where feather follicles lie. The stratum corneum of the epidermis is represented by corneocytes, and the germinal layer is represented by keratinocytes. The thickness of the skin of the back is less than that of the abdomen. At the same time, the thickness of the stratum corneum on the back is less than that of the germinal layer up to 105 days of age. On the abdomen, the thickness of the horny and germinal layers is almost the same at all ages. There is a thickening of the stratum corneum on the abdomen compared to the skin of the back. The skin is thickest on the abdomen and gradually thins towards the back. The epidermis is thin. The dermis is characterized by a dense interweaving of collagen fibers. Smooth muscle fibers in the skin and hair follicles develop by 42 days, and increase in volume by 105 days of age. The thinning of the feather cover in the sternum and belly area, caused by mechanical stress when poultry are kept on the floor, contributes to an increase in the absolute thickness of the epidermis in this area (about 3.5 times greater than in the back area), which is associated with its participation in protecting the skin from mechanical impacts damage.

Role of Pre-Operative Nutrition Status on Surgical Site Infection After Posterior Lumbar Interbody Fusion: A Retrospective Study.

Background: A retrospective case-control study to determine the role of pre-operative systemic and local nutritional factors on patients developing a surgical site infection (SSI) after posterior lumbar interbody fusion (PLIF). Surgical site infection after PLIF remains a substantial cause of morbidity. The literature demonstrates the prognosis of surgical patients is associated with pre-operative nutritional status that not only includes systemic nutritional factors, such as prognostic nutritional index (PNI), body mass index (BMI), and serum albumin, but also local nutritional factors, such as subcutaneous fat thickness at the surgical site, including absolute fat thickness and relative fat thickness. However, the role of pre-operative nutrition status in SSI after PLIF surgery remains unclear. Patients and Method: A retrospective review was performed on a consecutive cohort of 766 consecutive adult patients who underwent PLIF surgery for lumbar degenerative conditions between 2020 and 2021 at Second Xiangya Hospital. Previously identified risk factors as well as systemic and local nutritional factors nutritional factors were collected. Results: Among the 766 patients, 38 had post-operative SSI including 15 superficial SSI and 23 deep SSI. Univariable analysis showed that body weight, BMI, PNI, serum albumin, and relative fat thickness differed between the SSI and non-SSI groups. Multivariable logistic regression analysis showed that pre-operative PNI and relative fat thickness were independently associated with SSI after PLIF surgery. Conclusions: Lower pre-operative PNI and higher relative fat thickness are independent risk factors for developing deep SSI after PLIF.

Short-term echocardiographic follow-up after hospitalization for COVID-19: a focus on early post-acute changes.

Impaired physical functional status is one of the typical long-term sequelae of COVID-19 infection that significantly affects the quality of life and work capacity. Minor changes in cardiac structure and function that are unable to cause the manifestation of overt heart failure may remain undetected in COVID-19 convalescents, at the same time potentially contributing to the persistence of symptoms and development of long COVID syndrome. To study the typical features and short-term dynamics of cardiac remodeling and possible signs of cardiac dysfunction following hospitalization for COVID-19. This is a combined cross-sectional and longitudinal cohort study in which 176 hospitalized patients (93 female and 83 male, mean age 53.4 ± 13.6 years) with COVID-19 infection underwent comprehensive transthoracic echocardiography pre-discharge (22.6 ± 7.1 days from the onset of symptoms) with repeated evaluation after 1 month. The control group included 88 age-, sex-, height- and weight-matched healthy individuals, with a subset of those (n = 53) matched to the subset of non-hypertensive study participants (n = 106). Concentric left ventricular geometry was revealed in 59% of participants, including 43% of non-hypertensive subjects; predominantly Grade I diastolic dysfunction was found in 35 and 25% of patients, respectively. Other findings were naturally following from described phenotype of the left venticle and included a mild increase in the absolute and relative wall thickness (0.45 ± 0.07 vs. 0.39 ± 0.04, p < 0.001), worsening of diastolic indices (e' velocity 9.2 ± 2.2 vs. 11.3 ± 2.6 cm/s, p < 0.001, E/e' ratio 7.5 ± 1.8 vs. 6.8 ± 1.7, p = 0.002) and global longitudinal strain (17.5 ± 2.4 vs. 18.6 ± 2.2, p < 0.001). No significant improvement was found on re-evaluation at 1 month. Hospitalized patients recovering from COVID-19 were characterized by a high prevalence of left ventricular concentric remodeling, predominantly Grade I diastolic dysfunction, and a mild decrease in the longitudinal systolic function. These changes were less frequent but still prevalent in the non-hypertensive subgroup and largely persisted throughout the 1-month follow-up.

Effect of Repeated Intravitreal Injections in Glaucoma Spectrum Diseases.

To evaluate whether repeated intravitreal injections (IVI) with an anti-vascular endothelial growth factor (anti-VEGF) agent are associated with glaucomatous progression in eyes with glaucoma spectrum diseases (GSD). Single-center, retrospective, longitudinal study of patients with bilateral and similar GSD who: (1) received ≥8 IVI in only one eye during the study period; (2) had ≥2 retinal nerve fiber layer thickness (RNFL) measurements obtained by spectral-domain optical coherence tomography (SD-OCT) at least 12 months apart. The primary outcome was the absolute RNFL thickness change, comparing injected and fellow uninjected eyes. Linear mixed effects models were constructed, including a multivariable model. Sixty-eight eyes from 34 patients were included, 34 injected and 34 fellow uninjected eyes. Average baseline age was 67.68±21.77 years with a follow-up of 3.66±1.89 years and 25.12±14.49 IVI. RNFL thickness decreased significantly from 80.92±15.78 to 77.20±17.35 μm (p<0.001; -1.18±1.93 μm/year) in injected eyes and from 79.95±17.91 to 76.61±17.97 μm (p<0.001; -1.07±0.98 μm/year) in uninjected eyes. In a multivariable linear mixed model of injected eyes, only higher baseline RNFL thickness (p < 0.001) significantly predicted higher absolute RNFL thickness loss. Neither absolute RNFL thickness variation (p=0.716) nor RNFL rate (p=0.779) was significantly different between paired injected and uninjected eyes. Absolute IOP variation was not significantly different between groups (16.62±4.77 to 15.09±4.34 mmHg in injected eyes and 17.68±5.01 to 14.50±3.39 mmHg in fellow uninjected eyes; p=0.248). The proportion of eyes receiving glaucoma medical treatment increased significantly in both groups (55.9% to 76.5% in injected eyes; p=0.039; 58.8% to 76.5% in uninjected eyes; p = 0.031). The number of glaucoma medications also increased significantly in both groups (1.03±1.11 to 1.59±1.18 glaucoma medications in injected eyes; p=0.003; 1.09±1.11 to 1.56±1.19 glaucoma medications in uninjected eyes; p=0.003). Repeated IVI do not seem to accelerate glaucomatous progression. Future studies with a longer follow-up are needed.

Relative lateral wall thickness is an improved predictor for postoperative lateral wall fracture after trochanteric femoral fracture osteosynthesis

Lateral wall thickness is a known predictor for postoperative stability of trochanteric femoral fractures and occurrence of secondary lateral wall fractures. Currently, the AO/OTA classification relies on the absolute lateral wall thickness (aLWT) to distinguish between stable A1.3 and unstable A2.1 fractures that does not take interpersonal patient differences into account. Thus, a more individualized and accurate measure would be favorable. Therefore, we proposed and validated a new patient-specific measure—the relative lateral wall thickness (rLWT)—to consider individualized measures and hypothesized its higher sensitivity and specificity compared with aLWT. First, in 146 pelvic radiographs of patients without a trochanteric femoral fracture, the symmetry of both caput-collum-diaphyseal angle (CCD) and total trochanteric thickness (TTT) was assessed to determine whether the contralateral side can be used for rLWT determination. Then, data of 202 patients were re-evaluated to compare rLWT versus previously published aLWT. Bilateral symmetry was found for both CCD and TTT (p ≥ 0.827), implying that bone morphology and geometry of the contralateral intact side could be used to calculate rLWT. Validation revealed increased accuracy of the rLWT compared with the gold standard aLWT, with increased specificity by 3.5% (Number Needed to Treat = 64 patients) and sensitivity by 1% (Number Needed to Treat = 75 patients). The novel rLWT is a more accurate and individualized predictor of secondary lateral wall fractures compared with the standard aLWT. This study established the threshold of 50.5% rLWT as a reference value for predicting fracture stability in trochanteric femoral fractures.

Analysis of electrical resistance measurements as a potential determination method for coating thickness on powders

The electrical resistance of conductive and non-conductive coatings on non-conductive and conductive powders, respectively, is investigated under increasing external load. A specially designed equipment was used to deposit coatings on small and light as well as heavy powdery substances by DC magnetron sputtering. Several reference methods to predict or measure the absolute film thickness on powders are discussed.When measuring the electrical resistance of insulating powders coated with a metal, in this case hollow glass microspheres (HGMs) coated with copper, under increasing load, a typical resistance curve is found. This resistance curve is discussed in terms of percolation theory and the Heckel equation for powder compaction. The influence of coating thickness of the conductive coating is then evaluated and other factors like inhomogeneity of the coating are discussed. To reduce the influence of measurement parameters, selected experiments are interpreted under the concept of a force per grain, which is introduced and explained.To further substantiate the typical electrical resistance curve, stabilized and non-stabilized NMC811 powder is coated with aluminium and zirconium oxides of different thicknesses, corresponding to a conductive powder with an insulating coating. When comparing measurements for stabilized and non-stabilized powder, the perspective for electrical resistance measurements under increasing load becomes apparent, as it is possible to even detect surface modifications which are not known a priori.

Elevation and thickness of the 11–10 Kyr old ‘Sinkholes Salt’ layer in the Dead Sea: clues to past limnology, paleo-bathymetry and lake levels

The sinkholes along the Dead Sea (DS) shores form by dissolution of an 11–10 kyr old subsurface salt layer (hereafter named the ‘Sinkholes Salt’) that precipitated on the lake’s floor during periods of negative water balance, water level decline and salinity increase. We analyze the variations in absolute elevation and thickness of this layer in 40 boreholes along the western shores of the DS, reconstruct water-body stratification, past lake levels, and paleo-bathymetry during salt deposition, and comment on the role of the salt-layer elevation in future sinkhole formation. In the northern basin of the DS, maximum thickness of salt (~ 23 m) is found where salt top and bottom elevations are below ~ 440 meters below sea level (mbsl) and ~ 465 mbsl, respectively. Above these elevations the salt layer gradually thins out until 416 mbsl, above which it is no longer found. These relationships suggest that thermohaline stratification, with a thermocline at 25–30 m depth, similar to the present day dynamics of the DS, developed annually during the salt-precipitation period, giving rise to uniform salt accumulation below the thermocline and partial to full dissolution above it. Salt accumulation was controlled by the bathymetry of the lake and its configuration relative to the thermocline, and locally hampered by discharge of subaqueous under-saturated groundwater. The truncation of the salt layer at elevation of 416 mbsl is attributed to salt dissolution down to this elevation by a relatively diluted upper water layer that developed following inflow of fresh surface water at the end of the salt period. This event also marks the change to a positive water balance and lake level rise from its lowest stand of ~ 405 mbsl, as determined from limnological considerations.

Macular Thickness Fluctuations in Eyes With Diabetic Macular Edema Treated With Intravitreal Steroid.

Macular thickness fluctuations (MTF) over time may be more predictive of visual outcomes than absolute macular thickness in patients with diabetic macular edema (DME) treated with anti-vascular endothelial growth factor (anti-VEGF). It is unclear whether this association exists in DME patients treated with intravitreal steroids or whether steroids confer reduced MTF versus anti-VEGF treatments. MTF was compared before and after initiation of steroids in DME patients treated with intravitreal steroids. A mixed-effects linear regression model was used to determine the association between MTF and best-corrected visual acuity (BCVA). Mean 12-month MTF significantly decreased after steroid initiation (61.1 μm versus 53.5 μm, P = 0.04, n = 105 eyes). Mean BCVA after 12 months was not significantly different from baseline. No significant association between post-steroid MTF and 12-month BCVA was found. Steroid treatment decreases MTF while BCVA remains stable in DME patients previously treated with anti-VEGF. [Ophthalmic Surg Lasers Imaging Retina 2023;54:454-460.].

Middle meningeal artery embolization of septated chronic subdural hematomas.

Middle meningeal artery embolization (MMAE) has emerged as a promising new treatment for patients with chronic subdural hematomas (cSDH). Its efficacy, however, upon the subtype with a high rate of recurrence-septated cSDH-remains undetermined. From our prospective registry of patients with cSDH treated with MMAE, we classified patients based on the presence or absence of septations. The primary outcome was the rate of recurrence of cSDH. Secondary outcomes included a reduction in cSDH thickness, midline shift, and rate of reoperation. Among 80 patients with 99 cSDHs, the median age was 68 years (IQR 59-77) with 20% females. Twenty-eight cSDHs (35%) had septations identified on imaging. Surgical evacuation with burr holes was performed in 45% and craniotomy in 18.8%. Baseline characteristics between no-septations (no-SEP) and septations (SEP) groups were similar except for median age (SEP vs no-SEP, 72.5 vs. 65.5, p = 0.016). The recurrence rate was lower in the SEP group (SEP vs. no-SEP, 3 vs. 16.7%, p = 0.017) with higher odds of response from MMAE for septated lesions even when controlling for evacuation strategy and antithrombotic use (OR = 0.06, CI [0.006-0.536], p = 0.012). MMAE resulted in higher mean absolute thickness reduction (SEP vs. no-SEP, -8.2 vs. -4.8 mm, p = 0.016) with a similar midline shift change. The rate of reoperation did not differ (6.2 vs. 3.1%, p = 0.65). MMAE appears to be equal to potentially more effective in preventing the recurrence of cSDH in septated lesions. These findings may aid in patient selection.

Effect of boundary layer thickness on supersonic combustion in a scramjet combustor

In this study, the effect of boundary layer thickness on supersonic combustion in an ethylene-fueled scramjet combustor under Mach 5.5 flight conditions is studied by employing experiments, numerical simulations, and theoretical modeling. The plate flow quantitative results show that the absolute thickness of the boundary layer is higher for a larger combustor. But the relative thickness is thin. Although boundary layer thickness changes greatly as the combustion chamber scale enlarges, the influence on the transverse jet and cavity flow is limited. In contrast, the combustion chamber scale change has a great impact on the combustion. More violent flames exist in large-scale combustion chambers. A theoretical model demonstrated that a large subsonic region led to a long fuel residence time, resulting in larger Damköhler numbers. This indicated that a large combustor could maintain large combustion. Based on the above analysis, although the relative thickness of the boundary layer is thinner, the absolute subsonic region of the boundary layer full of combustion is increased, which is conducive to intense combustion. In addition, a verification calculation of the 50 mm shortening isolation section is carried out. It is found from the flame cloud diagram and the quantitative wall pressure data that the combustion is significantly weakened.

Ganglion Cell Complex Analysis: Correlations with Retinal Nerve Fiber Layer on Optical Coherence Tomography.

The aim of this review is to analyze the correlations between the changes in the ganglion cell complex (GCC) and the retinal nerve fiber layer (RNFL) on optical coherence tomography in different possible situations, especially in eyes with glaucoma. For glaucoma evaluation, several studies have suggested that in the early stages, GCC analysis, especially the thickness of the infero and that of the inferotemporal GCC layers, is a more sensitive examination than circumpapillary RNFL (pRNFL). In the moderate stages of glaucoma, inferior pRNFL thinning is better correlated with the disease than in advanced cases. Another strategy for glaucoma detection is to find any asymmetry of the ganglion cell-inner plexiform layers (GCIPL) between the two macular hemifields, because this finding is a valuable indicator for preperimetric glaucoma, better than the RNFL thickness or the absolute thickness parameters of GCIPL. In preperimetric and suspected glaucoma, GCC and pRNFL have better specificity and are superior to the visual field. In advanced stages, pRNFL and later, GCC reach the floor effect. Therefore, in this stage, it is more useful to evaluate the visual field for monitoring the progression of glaucoma. In conclusion, GCC and pRNFL are parameters that can be used for glaucoma diagnosis and monitoring of the progression of the disease, with each having a higher accuracy depending on the stage of the disease.

A drift isopach model for the southwestern Great Slave Lake region, Northwest Territories, Canada

ABSTRACT This study produced a drift thickness model for the southwestern Great Slave Lake area of northern Canada, using 12,692 lithostratigraphic records (seismic shothole drillers’ logs, diamond drill holes, petroleum wells), and field observations. Numerous algorithms and modelling parameters were tested using 6122 records of absolute drift thickness, and based on a cross-validation analysis, an empirical Bayesian kriging K-Bessel detrended algorithm was found to produce the best fit. The final model, incorporating selected maximum and minimum thickness estimate data, produced a root mean square error of 4.98 m, with 94.8% of the data points within ±2 m of the modelled drift thicknesses. The model identifies widespread areas of drift >10 m thick, and prominent southeast-northwest aligned bedrock ramps. Karst structures buried by ≤73 m of drift were identified southwest of Great Slave Lake and appear to be aligned with regional fault systems like ore-associated karst at Pine Point. These may be the source of anomalous glacial sediment-derived base metal indicators collected proximally to the west. The most striking drift anomaly is in Cameron Hills where the eastern and northern margins are comprised of shale and siltstone bedrock overlain by 20–40 m of glacial sediments, but the central and western uplands have petroleum well logs identifying glacial sediments up to 400 m thick. In addition to mineral exploration, results of this study provide baseline data that can be used predictively by the petroleum industry in designing future seismic and drilling (casing depth) operations, and by those modelling groundwater sources and flow.

Recommendation for strut designs of vertical axis wind turbines: Effects of strut profiles and connecting configurations on the aerodynamic performance

The strut is a necessary support structure that connects the vertical axis wind turbine blade to the rotating shaft and transfers the torque, and is one of the key factors affecting the aerodynamic performance of the wind turbine. However, research on struts is limited and the appropriate strut design remain uncertain. Therefore, in this paper, the struts of a straight-bladed vertical axis wind turbine are investigated by a three-dimensional computational fluid dynamics approach, to find the appropriate strut design parameters that minimize the impact on the aerodynamic performance. Thirty strut profiles with different chord lengths, thicknesses, areas, and streamlined shapes were parametrically created and analyzed, including a novel strut-specific profile proposed in this paper. Furthermore, all strut connecting parameters, such as spanwise and chordwise positions, connecting angle and fairing were investigated. The results show that the power loss of a vertical axis wind turbine has a relatively linear relationship with the dimensionless absolute thickness of the strut within a certain range. The strut chord length is another important influencing factor. Equal chord lengths of the strut and the blade should be avoided as much as possible. The proposed novel olivary strut profile has lower drag characteristics and more favorable geometrical structural properties compared to the most used NACA airfoil. The influence of the spanwise connecting position (within the range around the blade quarter span) is minor. But the chordwise position has a significant effect, and special attention should be paid to avoid the strut maximum thickness position connecting with the blade aerodynamic center, which will result in the greatest performance degradation. Analysis of the connecting angles shows that inclined struts are suitable for small wind turbines. The fairing is effective when the strut chord length is equal to or longer than the blade chord length. With these results, a set of recommended design parameters for vertical axis wind turbine struts is presented.

A simple model for daily basin-wide thermodynamic sea ice thickness growth retrieval

Abstract. As changes to Earth's polar climate accelerate, the need for robust, long–term sea ice thickness observation datasets for monitoring those changes and for verification of global climate models is clear. By linking an algorithm for retrieving snow–ice interface temperature from passive microwave satellite data to a thermodynamic sea ice energy balance relation known as Stefan's law, we have developed a retrieval method for estimating thermodynamic sea ice thickness growth from space: Stefan's Law Integrated Conducted Energy (SLICE). With an initial condition at the beginning of the sea ice growth season, the method can model basin-wide absolute sea ice thickness by combining the one-dimensional SLICE retrieval with an ice motion dataset. The advantages of the SLICE retrieval method include daily basin-wide coverage, lack of atmospheric reanalysis product input requirement, and a potential for use beginning in 1987. Validation of the retrieval against measurements from 10 ice mass balance buoys shows a mean correlation of 0.89 and a mean bias of 0.06 m over the course of an entire sea ice growth season. Despite its simplifications and assumptions relative to models like the Pan-Arctic Ice–Ocean Modeling and Assimilation System (PIOMAS), basin-wide SLICE performs nearly as well as PIOMAS when compared against CryoSat-2 and Operation IceBridge using a linear correlation between collocated points.

Total retinal thickness: a neglected factor in the evaluation of inner retinal thickness.

AimTo determine whether macular retinal nerve fibre layer (mRNFL) and ganglion cell-inner plexiform layer (GC-IPL) thicknesses vary by ethnicity after accounting for total retinal thickness.MethodsWe included healthy participants from the UK Biobank cohort who underwent macula-centred spectral domain-optical coherence tomography scans. mRNFL and GC-IPL thicknesses were determined for groups from different self-reported ethnic backgrounds. Multivariable regression models adjusting for covariables including age, gender, ethnicity and refractive error were built, with and without adjusting for total retinal thickness.Results20237 participants were analysed. Prior to accounting for total retinal thickness, mRNFL thickness was on average 0.9 μm (−1.2, –0.6; p<0.001) lower among Asians and 1.5 μm (−2.3, –0.6; p<0.001) lower among black participants compared with white participants. Prior to accounting for total retinal thickness, the average GC-IPL thickness was 1.9 μm (−2.5, –1.4; p<0.001) lower among Asians compared with white participants, and 2.4 μm (−3.9, –1.0; p=0.001) lower among black participants compared with white participants. After accounting for total retinal thickness, the layer thicknesses were not significantly different among ethnic groups. When considered as a proportion of total retinal thickness, mRNFL thickness was ~0.1 and GC-IPL thickness was ~0.2 across age, gender and ethnic groups.ConclusionsThe previously reported ethnic differences in layer thickness among groups are likely driven by differences in total retinal thickness. Our results suggest using layer thickness ratio (retinal layer thicknesses/total retinal thickness) rather than absolute thickness values when comparing retinal layer thicknesses across groups.