Standard Upright Research Articles

Design and numerical analysis of bicycle driver compartment area through CFD simulation

Upright-seat bicycles exhibit poor aerodynamics, with both rider and bicycle generating significant drag intensified by wind resistance, cold air, and rainfall. This research's aim involves designing and evaluating a bicycle compartment through CFD simulation. Beginning with a standard upright mountain bike model, six conceptual models serve to assess drag, lift, and streamline efficiency. Model 0 (original) provides baseline aerodynamics, indicating a drag coefficient of 0.52, closely aligning with the experimentally measured 0.5. Modifications initiate with Model 1, where rounded frontal corners decrease lift and drag. Model 3 achieves further drag reduction to 0.437 by increasing the rounding radius. Model 4 includes a 350 mm vertical vortex splitter, resulting in a drag coefficient of 0.425. Model 5 integrates horizontal and vertical splitters with chamfering and slanting, while Model 6 adds a rear teardrop angle, enhancing streamlining and reducing recirculation, yielding a drag coefficient of 0.295. Experimental validation in a wind tunnel records a drag coefficient of 0.311, reflecting a 5.42% error due to wind tunnel limitations. Model 6 emerges as the most aerodynamically efficient design.

Bringing cell biology into classroom: tips to culture and observe skeletal muscle cells in high school and college

Watching living cells through a microscope is much more exciting than seeing pictures of cells in high school and college textbooks. However, bringing cell cultures into the classroom is challenging for biology teachers since culturing cells requires sophisticated and expensive instruments such as a CO2 incubator and an inverted phase-contrast microscope. Here, we describe easy and affordable methods to culture and observe skeletal muscle cells using the L-15 culture medium, tissue culture flask, standard dry incubator, standard upright microscope, and modified Smartphone microscope. Watching natural living cells in a “Do-It-Yourself (DIY)” way may inspire more students’ interest in cell biology.

Impact of relaxing incisions on maxillofacial growth following Sommerlad–Furlow modified technique in patients with isolated cleft palate: a preliminary comparative study

ObjectiveTo estimate the impact of relaxing incisions on maxillofacial growth following Sommerlad-Furlow modified technique in patients with isolated cleft palate.Study designA Retrospective Cohort Study.MethodsA total of 90 participants, 60 patients with non-syndromic isolated soft and hard cleft palate underwent primary palatoplasty (30 patients received the Sommerlad-Furlow modified technique without relaxing incision (S.F−RI group), and 30 received Sommerlad-Furlow modified technique with relaxing (S.F+RI group) with no significant difference found between them regarding the cleft type, cleft width, and age at repair. While the other 30 were healthy noncleft participants with skeletal class I pattern as a Control group. The control group (C group) was matched with the patient groups in number, age, and sex. All participants had lateral cephalometric radiographs at least 5 years old age. The lateral cephalometric radiographs were taken with the same equipment by the same experienced radiologist while the participants were in centric occlusion and a standardized upright position, with the transporionic axis and Frankfort horizontal plane parallel to the surface of the floor. A well-trained assessor (S. Elayah) used DOLPHIN Imaging Software to trace twice to eliminate measurement errors. All the study variables were measured using stable landmarks, including 12 linear and 10 angular variants.ResultsThe mean age at collection of cephalograms was 6.03 ± 0.80 in the S.F+RI group, 5.96 ± 0.76 in the S.F−RI group, and 5.91 ± 0.87 in the C group.Regarding cranial base, the results showed no statistically significant differences between the three groups in S–N and S–N-Ba. While the S.F+R.I group had a significantly shortest S-Ba than the S.F−R.I & C groups (P = 0.01 & P < 0.01), but there was no statistically significant difference between S.F−R.I & C groups (P = 0.71).Regarding the skeletal maxilla, there was no significant difference between the S.F+R.I and S.F−R.I groups in all linear measurements (N-ANS and S-PM) except Co-A, the S.F+R.I group had significantly shorter Co-A than the S.F−R.I & C groups (P = < 0.01). While the angular measurement, S.F+R.I group had significantly less SNA angle than the S.F−R.I & C groups (P = < 0.01).Regarding mandibular bone, there were no statistically significant differences in all linear and angular mandibular measurements between the S.F+R.I and S.F−R.I.groups.Regarding intermaxillary relation, the S.F+R.I group had significant differences in Co-Gn—Co-A and ANB compared to the S.F−R.I & C groups (P = < 0.01). While there was no statistically significant difference in PP-MP between the three groups.ConclusionAs a preliminary report, the Sommerlad-Furlow modified technique without relaxing incisions was found to have a good maxillary positioning in the face and a satisfactory intermaxillary relationship compared to the Sommerlad-Furlow modified technique with relaxing incisions.

3D printed chamber for live cell imaging on an upright epifluorescence microscope

ABSTRACT Live cell imaging is a standard technique in experimental biology that enables the observation of isolated cells and tissue slices in real time and the testing of cellular responses to changes in buffer composition. However, most live cell imaging devices require the use of dedicated microscopes and/or specialised stage adaptors, and come at a reasonably high cost. We employed 3D printing technology to create a low-cost imaging chamber with side ports to exchange fluids, to be used on upright microscopes. The chamber increased the functionality of a standard upright epifluorescent microscope to allow dynamic, real-time calcium imaging of cultured hypothalamic astrocytes from mice, and to test the effects of ATP stimulation upon calcium signalling. It was also used on slices obtained from the mouse brain using a brain matrix slicer. The advantages of this chamber include a very simple design that can be used with upright epifluorescence microscopes, does not require any special stage adaptor, and includes ports to permit fluid exchange during imaging. This chamber is ideal for educational settings with undergraduate laboratories that do not have access to dedicated inverted fluorescent microscopes for tissue culture experiments.

High-Sensitivity Intrinsic Optical Signal Imaging Through Flexible, Low-Cost Adaptations of an Upright Microscope.

Intrinsic optical signal imaging (IOSI) is a staple technique in modern neuroscience. Pioneered >30 years ago, IOSI allows macroscopic mapping of neuronal activity throughout the cortex. The technique has been used to study sensory processing and experience-dependent plasticity, and is often used as an adjunctive procedure to localize cortical areas for subsequent targeting by other imaging or physiology techniques. Despite the ubiquity of IOSI in neuroscience, there are few commercially available turn-key IOSI systems. As a result, investigators have typically resorted to building their own imaging systems. Over the years, simplified systems built either as dedicated rigs or incorporated into existing microscope platforms have been developed. Here we present a straightforward set of adaptations that can be applied to any standard upright microscope, using readily available, inexpensive, commercial parts for illumination, optics, and signal detection, that enables high-sensitivity IOSI. Using these adaptations, we are able to readily map sensory-evoked signals across the somatosensory and visual cortex, including single-whisker barrel cortical activity maps in mice. We show that these IOSI maps are highly reproducible across animals and can be used to study plasticity mechanisms in the somatosensory cortex. We also provide open-source applications to control illumination and analyze raw data to generate activity maps. We anticipate that these resources will be useful for neuroscience investigators looking to add IOSI capabilities to an existing microscope in the laboratory on a budget.

Classification of Free-Living Body Posture with ECG Patch Accelerometers: Application to the Multicenter AIDS Cohort Study.

As health studies increasingly monitor free-living heart performance via ECG patches with accelerometers, researchers will seek to investigate cardio-electrical responses to physical activity and sedentary behavior, increasing demand for fast, scalable methods to process accelerometer data. We extend a posture classification algorithm for accelerometers in ECG patches when researchers do not have ground-truth labels or other reference measurements (i.e., upright measurement). Men living with and without HIV in the Multicenter AIDS Cohort study wore the Zio XT® for up to two weeks (n = 1,250). Our novel extensions for posture classification include (1) estimation of an upright posture for each individual without a reference upright measurement; (2) correction of the upright estimate for device removal and re-positioning using novel spherical change-point detection; and (3) classification of upright and recumbent periods using a clustering and voting process rather than a simple inclination threshold used in other algorithms. As no posture labels exist in the free-living environment, we perform numerous sensitivity analyses and evaluate the algorithm against labelled data from the Towson Accelerometer Study, where participants wore accelerometers at the waist. On average, 87.1% of participants were recumbent at 4am and 15.5% were recumbent at 1pm. Participants were recumbent 54 minutes longer on weekends compared to weekdays. Performance was good in comparison to labelled data in a separate, controlled setting (accuracy = 96.0%, sensitivity = 97.5%, specificity = 95.9%). Posture may be classified in the free-living environment from accelerometers in ECG patches even without measuring a standard upright position. Furthermore, algorithms that fail to account for individuals who rotate and re-attach the accelerometer may fail in the free-living environment.

Evaluation of Posturographic and Neuromuscular Parameters during Upright Stance and Hand Standing: A Pilot Study

Upright bipedal posture is the physiological human posture; however, it is not the only possible form of human standing; indeed, an inverted position, a handstand, is required during gymnastics or other sports. Thus, this study aimed to understand the differences between the two standing strategies from a postural and neuromuscular perspective. Thirteen gymnasts with at least three years of sports experience underwent a baropodometric assessment and a surface electromyography (sEMG) examination in a standard upright bipodalic stance and during a handstand. The sEMG examination was performed on the gastrocnemius during an upright stance and on the flexor carpi radialis during the handstand. Limb weight distribution presented differences between the two vertical stances (p < 0.01). During the handstand, the weight ratio was prevalently observed on the palm of the hand for both hands with a significant difference between the front and rear aspect of the hand compared to the standing tasks (p < 0.01). Normalized sEMG amplitude showed significant differences during bipedal standing and hand standing; however, over a 5 s period, the normalized median frequency (MDF) value was similar for the two tasks. Both standing tasks presented similar postural weight managing patterns when analysed on the frontal plane, but they were different on the sagittal plane. In addition, the neuromuscular patterns during a 5 s window differ in amplitude but not for the frequency domain.

Comparison of trunk muscle exercises in supine position during short arm centrifugation with 1g at centre of mass and upright in 1g.

Spaceflight is associated with reduced antigravitational muscle activity, which results in trunk muscle atrophy and may contribute to post-flight postural and spinal instability. Exercise in artificial gravity (AG) performed via short-arm human centrifugation (SAHC) is a promising multi-organ countermeasure, especially to mitigate microgravity-induced postural muscle atrophy. Here, we compared trunk muscular activity (mm. rectus abdominis, ext. obliques and multifidi), cardiovascular response and tolerability of trunk muscle exercises performed during centrifugation with 1 g at individual center of mass on a SAHC against standard upright exercising. We recorded heart rate, blood pressure, surface trunk muscle activity, motion sickness and rating of perceived exertion (BORG) of 12 participants (8 male/4 female, 34 ± 7 years, 178.4 ± 8.2 cm, 72.1 ± 9.6 kg). Heart rate was significantly increased (p < 0.001) during exercises without differences in conditions. Systolic blood pressure was higher (p < 0.001) during centrifugation with a delayed rise during exercises in upright condition. Diastolic blood pressure was lower in upright (p = 0.018) compared to counter-clockwise but not to clockwise centrifugation. Target muscle activation were comparable between conditions, although activity of multifidi was lower (clockwise: p = 0.003, counter-clockwise: p < 0.001) and rectus abdominis were higher (clockwise: p = 0.0023, counter-clockwise: < 0.001) during centrifugation in one exercise type. No sessions were terminated, BORG scoring reflected a relevant training intensity and no significant increase in motion sickness was reported during centrifugation. Thus, exercising trunk muscles during centrifugation generates comparable targeted muscular and heart rate response and appears to be well tolerated. Differences in blood pressure were relatively minor and not indicative of haemodynamic challenge. SAHC-based muscle training is a candidate to reduce microgravity-induced inter-vertebral disc pathology and trunk muscle atrophy. However, further optimization is required prior to performance of a training study for individuals with trunk muscle atrophy/dysfunction.

How often does the preoperative plan for freehand pedicle screw placement match the actual surgical execution in adolescent idiopathic scoliosis?

To provide a baseline for comparison with future advancements, this study determined the accuracy of preoperative planning of pedicle screw placement using standard radiographs for posterior fusion (PSF) for adolescent idiopathic scoliosis (AIS). Ninety-five patients with AIS planned for PSF were prospectively enrolled. Preoperative planning was based upon standard upright posteroanterior and lateral radiographs. The planned number of screws to be placed at each level was recorded. Intraoperatively, all screws were placed by freehand technique. The number of successfully placed screws and the reasons for abandoning screw placement were documented. There were a total of 1783 pedicle screws planned preoperatively. The average planned implant density was 2.0 implants/vertebra. A total of 1723 (96.6%) of the planned screws were placed successfully. Fourteen (0.8%) screws were abandoned after attempted placement (range 0-2 screws/case). Of 241 screws planned in pedicles noted to be "hypoplastic," 13 resulted in the use of a hook or no instrumentation. The placement was not attempted for 49 (range 0-7/case) planned screws due to intraoperative decision-making and a sense that the curve was flexible enough not to require every screw. Three cases (3.2%) required instrumentation of an additional level. Standard spine radiographs allow for accurate preoperative planning for freehand pedicle screw placement in AIS. Ninety-seven percent of planned screws were placed successfully. The primary reason for deviation from the preoperative plan was intraoperative surgeon decision-making rather than difficulty with screw placement. This study will serve as a baseline when considering the utilization of navigation in PSF for AIS.

Development of Planar Illumination Strategies for Solving Mysteries in the Sub-Cellular Realm.

Optical microscopy has vastly expanded the frontiers of structural and functional biology, due to the non-invasive probing of dynamic volumes in vivo. However, traditional widefield microscopy illuminating the entire field of view (FOV) is adversely affected by out-of-focus light scatter. Consequently, standard upright or inverted microscopes are inept in sampling diffraction-limited volumes smaller than the optical system’s point spread function (PSF). Over the last few decades, several planar and structured (sinusoidal) illumination modalities have offered unprecedented access to sub-cellular organelles and 4D (3D + time) image acquisition. Furthermore, these optical sectioning systems remain unaffected by the size of biological samples, providing high signal-to-noise (SNR) ratios for objective lenses (OLs) with long working distances (WDs). This review aims to guide biologists regarding planar illumination strategies, capable of harnessing sub-micron spatial resolution with a millimeter depth of penetration.

Evaluation of cephalometric indices in patients with obstructive sleep apnea in comparison with healthy individuals

Study objectivesThis study aimed to evaluate the cephalometric parameters related to obstructive sleep apnea (OSA). MethodsTwenty-four patients with OSA diagnosis and Apnea-Hypopnea Index (AHI) ≥15 in overnight polysomnography were recruited. A similar number of control participants were selected based on the absence of OSA clinical presentations through evaluation with the Epworth Sleepiness Scale and STOP-Bang questionnaires. Two groups were matched for age, sex, and body mass index. The standardized upright lateral cephalograms of all participants were obtained; afterward, skeletal and soft tissue landmarks were traced and digitized. ResultsWe observed that in patients with OSA, mandibular ramus length was significantly bigger (p = 0.02), and the mandibular plane made a greater angle with the line passing through the nasion and the sella (p < 0.001). They had a retro-positioned mandible (p < 0.001), and the hyoid bone was placed inferiorly (p < 0.001) compared to control participants. Regarding the differences related to soft tissue, they had elongated tongue (p < 0.001) and soft palate (p < 0.001). The ANB angle was negatively correlated with diseases severity (r = −0.49, p = 0.013). Among different cephalometric measurements, the H-MP and TL with the cut-off values of 14 and 67 mm had the highest power to predict OSA. ConclusionsThe patients with OSA exhibited longer soft palate and tongue, inferiorly positioned hyoid bones, and retruded and longer mandible. The disease severity was mainly related to the retruded mandible. Moreover, hyoid bone position and tongue length were the most reliable measures to predict OSA.

Application of complex neck loads to human spine at the occipital condyle joint: Implications for nonstandard postures for automated vehicles

Objective The automotive industry's shift toward automated vehicles allows the occupants to assume postures different from the standard upright seated position. Injury criteria assessments are needed under these nonstandard postures to advance safety. The objective of this study is to develop a new device that can position the human cadaver head-neck structures in different nonstandard pre-postures using custom devices and apply external loading anticipated in modern and future automotive and military scenarios. Methods An isolated head to T1 human cadaver specimen was attached to a load cell at T1. The load cell was fixed to the top of a six-degree-of-freedom custom spinal positioning device to orient the specimen such that the occipital condyle joint was in line with the torque axis of a custom angular displacement test device. The angular device converted the linear motion of a vertically oriented electro-hydraulic piston to a torque about the occipital condyle joint of the specimen. The head was pre-rotated in the axial plane, approximately 20 degrees to the left, while maintaining the coronal alignment of the lower cervical spine. Targets were secured at the head and spine (details in the body of the manuscript), and their three-dimensional positions were measured using a seven-camera optical motion capture system. Right and then left lateral bending tests were conducted. Occipital condyle joint loads were determined from the superior load cell, and the stiffness difference between the left and right lateral bending was determined. Results The peak coronal bending moments were 27.1 Nm and 47.6 Nm for the right and left lateral bending tests. At the time of the peak x-moment, the y moments were 1.6 and 9.1 Nm, and the z moments were 3.1 and 4.8 Nm. The head angle with respect to T1 at the time of peak x-moments was 28.1 and 27.7 deg about x, 11.0 and 11.7 deg about y, and 33.9 and 21.8 deg about z axes for the right and lateral bending tests. C1 left lateral mass fractured following the left lateral bending test. Conclusions The stiffness of the spine increased by approximately three times due to asymmetries in posture and loading. The present system of custom spinal positioning and angular displacement test devices and loading methodologies can be used in conjunction with a conventional piston testing apparatus to conduct additional experiments to delineate the injury patterns and mechanisms and develop injury criteria applicable to modern and future vehicle environments.

The differences in whole-body sagittal alignment between different postures in young, healthy adults

Study designProspective study.ObjectiveTo identify the radiographic differences between the standard upright position and the natural and comfortable upright position.MethodsThe radiographic data of 50 young and healthy adults were evaluated, and parameters including the global cervical angle (GCA), global thoracic angle (GTA), global lumbar angle (GLA) were used to depict the spine profile; the distance from the cranial center to the posterior corner of S1 (CSVA-S), the center of the hip (CSVA-H), the center of the knee (CSVA-K) and the center of the ankle (CSVA-A) were measured in both the standard and the natural and comfortable upright positions to assess whole-body balance.ResultsSignificant differences were observed in the GCA (17.39 ± 6.90 vs. 10.90 ± 3.77, p < .001), GTA (25.63 ± 7.27 vs. 45.42 ± 8.15 p < .001), GLA (42.64 ± 8.05 vs. 20.21 ± 7.47 p < .001), CSVA-S (0.33 ± 2.76 cm vs. 8.54 ± 3.78 cm, p < 0.001), CSVA-H (1.53 ± 3.11 cm vs. 5.71 ± 3.26 cm, p < 0.001), CSVA-K (3.58 ± 2.47 cm vs. 5.22 ± 2.69 cm, p = 0.002) and CSVA-A (1.79 ± 1.92 cm vs. 4.79 ± 2.51 cm, p < 0.001) between the two different standing postures. Compared with the standard upright position, the natural and comfortable upright position results in a more kyphotic spine profile.ConclusionSignificant differences in sagittal radiographic parameters were found between the standard upright position and the natural and comfortable upright position; the latter served as a marker for energy conservation during standing and revealed a more kyphotic spinal profile. The standard upright position and natural and comfortable upright position are equally important and should be addressed before a surgical plan is developed for patients who need surgery.

Coronal and sagittal spinal alignment in lumbar disc herniation with scoliosis and trunk shift

BackgroundTo investigate the incidence of scoliosis and trunk shift in patients with LDH (lumbar disc herniation) and analyze the differences in spinopelvic alignment among patients with or without trunk shift and non-symptom controls.Materials and methodsAll included subjects had standard upright antero-posterior and lateral radiographs of the whole spine taken. Evidence of disc herniation was confirmed by computed tomography or magnetic resonance imaging. The parameters measured included trunk shift and Cobb angle, TK (thoracic kyphosis), TLK (thoraco-lumbar junction kyphosis), LL (lumbar lordosis), PI (pelvic incidence), SS (sacral slope), PT (pelvic tilt) and SVA (sagittal vertical axis).ResultsSixty-eight patients with LDH and 61 controls were included. There were significantly more male patients with trunk shift than the patients without trunk shift. Forty-two patients had curve magnitudes ranging from 5 to 38°. The trunk shift ranged from 0.5 to 7.3 cm. A total of 54.76% of patients had a disc herniation on the concave side of the main curve. Fifty percent of patients showed a trunk shift towards the opposite side of disc herniation. There were significant differences in spinopelvic parameters among groups. Significant correlations were also observed between several spinopelvic parameters in the three groups. However, the degrees of correlations among the spinopelvic parameters differed among the three groups.ConclusionSpinal sagittal morphology in LDH patients with trunk shift exhibits a more anterior shift of the C7 plumb line, less LL, and a more horizontal sacrum. Correlation analysis indicated a disharmonious spinopelvic interaction and a change in the compensatory model in patients with LDH.

Multi-flow channel bioreactor enables real-time monitoring of cellular dynamics in 3D engineered tissue

The key to understanding, harnessing, and manipulating natural biological processes for the benefit of tissue engineering lies in providing a controllable dynamic environment for tissue development in vitro while being able to track cell activity in real time. This work presents a multi-channel bioreactor specifically designed to enable on-line imaging of fluorescently labeled cells embedded in replicated 3D engineered constructs subjected to different flow conditions. The images are acquired in 3D using a standard upright confocal microscope and further analyzed and quantified by computer vision. The platform is used to characterize and quantify the pace and directionality of angiogenic processes induced by flow. The presented apparatus bears considerable potential to advance scientific research, from basic research pursuing the effect of flow versus static conditions on 3D scaffolds and cell types, to clinically oriented modeling in drug screening and cytotoxicity assays.

RETRACTED ARTICLE: Subjective visual vertical in virtual reality (Curator SVV): validation and normative data

Subjective visual vertical (SVV) assesses the ability to perceive verticality, which is a measure of vestibular otolithic function. Vestibular lesions influence this perception of verticality. We developed a method using virtual reality (VR) display and an Android software application named ‘Curator SVV’. The virtual reality SVV (Curator SVV) consisted of ten readily identifiable artworks projected by a Samsung phone S6 which is inserted into a virtual reality headset. In the first study, 20 patients had there SVV assessed with two devices: (1) a commercially available SVV measurement device (VestiTest®) and (2) a virtual reality SVV using the Curator SVV application. In a second study, 32 healthy subjects had their SVV assessed by the Curator SVV application whilst sitting in a chair. In the first study, there was no significant difference (p = 0.44, paired t test and p = 0.01, test of equivalence) between results obtained by Curator SVV and the commercially available device. In the second study, the average angle measured for healthy subjects was 0.00° ± 0.85°. The normal range (mean ± 2 SD) was ± 2° in standard upright position. We were able to demonstrate that the Curator SVV can be readily employed as an objective, non-invasive and affordable means of assessing otolith function in the clinical context. We validated this novel methodology by finding strong quantitative parity between a standard commercial SVV unit and the VR Curator SVV method. Our very lightweight and mobile device can be employed in clinical contexts including at the bedside and in different head and body positions.

L5 pedicle subtraction osteotomy: indication, surgical technique and specificities.

To evaluate the radiographic, functional outcomes, complications and surgical specificities of L5 pedicle subtraction osteotomy for fixed sagittal and coronal malalignment. A retrospective cohort of consecutive patients with prospectively collected data. Ten patients who underwent PSO at L5 were eligible for a 2-year minimum follow-up (average, 4.0years). Patients were evaluated by standardized upright radiographs. Preoperative and postoperative radiographies, surgical data and complications were collected. All surgeries were revision surgeries. The mean lumbar lordosis before surgery was -22.5° (range, 8° to -33°) and improved to -58.5° (range, -40° to -79°). The sagittal vertical axis demonstrated a preoperative mean sagittal malalignment of 13.7cm (range 3.5 to 20cm), with correction to 4.6cm postoperatively. Three patients required additional surgery at the latest follow-up for rod breakage. PSO of L5 can be a safe and effective technique to treat and correct fixed sagittal imbalance and provide biomechanical stability. The high complication rate mandates a careful assessment of the risk/benefit ratio of such a major surgery. Most patients are satisfied, particularly when sagittal balance is achieved.

Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries

Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection's standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45° bent position is overestimated compared to the upright phantom below 1MeV by as much as 27% and 82% in the 90° position. The effective dose in the 45° bent position was comparable to that in the 90° bent position for the LLAT and RLAT irradiation geometries. However, the upright phantom underestimates the effective dose to PIMAL in the LLAT and RLAT geometries by as much as 30% at 50keV.

The effect of settling on cytotoxicity evaluation of SiO2 nanoparticles

The in vitro cytotoxicity of nanomaterials is commonly assessed by monitoring cell viability under exposure to their suspensions. The actual nanoparticle dose delivered to cells for the same nominal nanoparticle concentration may depend on their settling rate. The goal here is to evaluate quantitatively the importance of settling for the in vitro cytotoxicity evaluation of aerosol-made, fractal-like SiO2 nanoparticles that have similar agglomerate size and structure but varying primary particle diameter. Their deposition rate is measured by UV-visible spectroscopy and their in vitro cytotoxicity is evaluated in both standard upright and inverted murine macrophage culture configurations. Silicas of larger primary particles settle faster and appear more cytotoxic than those of smaller ones in standard upright cell cultures. In contrast, with inverted cell cultures all silicas show similar and much lower cytotoxicity revealing the impact of nanoparticle settling in such assessments that are benchmarked with H2O2 solutions and nanosilver suspensions. When the measured settled fractions are accounted for, the reduction in cell viability depends on the surface of SiO2 nanoparticles deposited onto cells regardless of primary particle size. This study quantitatively demonstrates the importance of nanoparticle settling for in vitro studies of the widely used fumed SiO2 and highlights that settling measurements combined with inverted-upright cell cultures can be useful tools in nanotoxicology studies.

Corneal Endothelial Cell Density in Children: Normative Data From Birth to 5 Years Old

To establish a normative database of endothelial cell density (ECD) using invivo specular microscopy in children under 5 years old. Cross-sectional study. Specular microscopy was performed during a clinic visit in cooperative children in the standard upright position. In uncooperative children, specular microscopy was performed in the lateral decubitus position under general anesthesia, before surgery for other reasons. Corneal diameter (CD) was measured in children undergoing general anesthesia and was stratified according to age. One hundred and eighteen eyes of 118 patients were included in the study. The mean patient age was 2.6 ± 1.4 years (range 0.1-5 years) and the mean ECD was 3746 ± 370 cells/mm2 (range 3145-5013 cells/mm2). The mean CD under 2 years of age was 11.85 ± 0.57mm (n= 40, range 10.50-12.75mm). Up to 2 years of age, ECD was more inversely correlated with CD than with age (r=-0.61, P < .0001; r=-0.38, P= .01, respectively). In contrast, after the age of 2 years, the ECD was inversely correlated with age but not with CD (r=-0.27, P= .02; r=-0.24, P= .2). Between the first and second year of life, the rate of ECD decrease was significantly higher than between 2 and 5 years of age (8.2%, 334 cells/mm2 vs 2.7%, 100 cells/mm2 a year, respectively). In the first 2 years of life there is a rapid decline in ECD, which is likely related to growth in CD and hence surface area. After the cornea reaches adult size, the ECD decreases at a rate similar to that reported in adults.