Determination of axial and lateral exciton diffusion length in GaN by electron energy dependent cathodoluminescence

NASA Astrophysics Data System (ADS)

Hocker, Matthias; Maier, Pascal; Jerg, Lisa; Tischer, Ingo; Neusser, Gregor; Kranz, Christine; Pristovsek, Markus; Humphreys, Colin J.; Leute, Robert A. R.; Heinz, Dominik; Rettig, Oliver; Scholz, Ferdinand; Thonke, Klaus

2016-08-01

We demonstrate the application of low-temperature cathodoluminescence (CL) with high lateral, depth, and spectral resolution to determine both the lateral (i.e., perpendicular to the incident primary electron beam) and axial (i.e., parallel to the electron beam) diffusion length of excitons in semiconductor materials. The lateral diffusion length in GaN is investigated by the decrease of the GaN-related luminescence signal when approaching an interface to Ga(In)N based quantum well stripes. The axial diffusion length in GaN is evaluated from a comparison of the results of depth-resolved CL spectroscopy (DRCLS) measurements with predictions from Monte Carlo simulations on the size and shape of the excitation volume. The lateral diffusion length was found to be (95 ± 40) nm for nominally undoped GaN, and the axial exciton diffusion length was determined to be (150 ± 25) nm. The application of the DRCLS method is also presented on a semipolar (11 2 ¯ 2 ) sample, resulting in a value of (70 ± 10) nm in p-type GaN.

Effect of axial length on laser spot size during photodynamic therapy: an experimental study in monkeys.

PubMed

Kondo, Mineo; Ito, Yasuki; Miyata, Kentaro; Kondo, Nagako; Ishikawa, Kohei; Terasaki, Hiroko

2006-01-01

To investigate the effect of shorter axial length on the laser spot size and laser energy during photodynamic therapy (PDT) in monkeys. Experimental study with four rhesus monkeys. PDT was performed on the normal retina of monkeys whose ocular axial lengths are shorter (19.55 to 20.25 mm) than that of humans. After the PDT, the eyes were enucleated, and the diameter of the irradiated laser spot was measured with a microcaliper. The area of actual laser spot was only 0.56 to 0.61 times of the planned area, which indicated that the laser energy/area was 1.64 to 1.78 times more intense than planned initially. These results are the in vivo demonstration that the diameter of PDT laser spot is smaller for eyes with shorter axial lengths.

Near-Infrared Irradiation Increases Length of Axial Pattern Flap Survival in Rats.

PubMed

Yasunaga, Yoshichika; Matsuo, Kiyoshi; Tanaka, Yohei; Yuzuriha, Shunsuke

2017-01-01

Objective: We previously reported that near-infrared irradiation nonthermally induces long-lasting vasodilation of the subdermal plexus by causing apoptosis of vascular smooth muscle cells. To clarify the possible application of near-infrared irradiation to prevent skin flap necrosis, we evaluated the length of axial pattern flap survival in rats by near-infrared irradiation. Methods: A bilaterally symmetric island skin flap was elevated under the panniculus carnosus on the rat dorsum. Half of the flap was subjected to near-infrared irradiation just before flap elevation with a device that simulates solar radiation, which has a specialized contact cooling apparatus to avoid thermal effects. The length of flap survival of the near-infrared irradiated side was measured 7 days after flap elevation and compared with the nonirradiated side. Results: The irradiated side showed elongation of flap survival compared with the nonirradiated side (73.3 ± 11.7 mm vs 67.3 ± 14.9 mm, respectively, P = .03). Conclusions: Near-infrared irradiation increases the survival length of axial pattern flaps in rats.

Prediction of an Apparent Flame Length in a Co-Axial Jet Diffusion Flame Combustor.

DTIC Science & Technology

1983-04-01

This report is comprised of two parts. In Part I a predictive model for an apparent flame length in a co-axial jet diffusion flame combustor is...Overall mass transfer coefficient, evaluated from an empirically developed correlation, is employed to predict total flame length . Comparison of the...experimental and predicted data on total flame length shows a reasonable agreement within sixteen percent over the investigated air and fuel flow rate

Refraction and the axial length of the eyeball in patients with the optic disc drusen.

PubMed

Obuchowska, Iwona; Mariak, Zofia

2009-01-01

The aim of the study was to demonstrate the relationship between the optic disc drusen (ODD) and the axial length of the eyeball as well as refractive error. We examined prospectively 40 patients with ODD, 18 men and 22 women, age range from 34 to 69 years. All subjects underwent full ophthalmic examination, visual field testing and color-coded duplex sonography of the ocular vessels. Refraction was determined with an autorefractometer (Topcon RM-8000B) and further refined subjectively. Spherical equivalent refraction was calculated as the spherical dioptre plus one half of the cylindrical dioptre. Axial lengths were measured with a Sonomed ultrasound scanner model E-Z Scan AB5500. Clinical signs were observed in 65% of the eyes with drusen, among them, 38% had symptoms of visual acuity loss and all had visual fields defects. There were 21 eyes (18 eyes with and 3 without drusen), with a recorded refractive error. Significant differences in hyperopia were observed between the eyes with and without drusen (p = 0.048). The rate of occurrence of myopia did not differ significantly between affected and unaffected eyes (p = 0.06). The mean spherical equivalent refraction and axial dimensions of the eye differed significantly among the groups of eyes with and without drusen (p < 0.05). Significant differences in mean values of peak-systolic and end-diastolic velocities (p < 0.001) as well as in the resistivity index (p = 0.047) were observed between eyes with and without drusen. The optic disc drusen are often associated with shorter and hyperopic eyes. This anatomical conditions and vascular factors may contribute to pathogenesis of drusen.

Effect of central corneal thickness, corneal curvature, and axial length on applanation tonometry.

PubMed

Kohlhaas, Markus; Boehm, Andreas G; Spoerl, Eberhard; Pürsten, Antje; Grein, Hans J; Pillunat, Lutz E

2006-04-01

To evaluate the effect of central corneal thickness (CCT), corneal curvature, and axial length on applanation tonometry in an in vivo study. In a masked, prospective clinical trial, we examined 125 eyes of 125 patients scheduled for cataract surgery. Corneal curvature was measured by means of keratometry and axial length by A-scan ultrasonography. By cannulating the anterior chamber before surgery, intraocular pressure (IOP) was set to 20, 35, and 50 mm Hg in a closed system by means of a water column. After measuring thickness, the IOP was measured with an applanation tonometer. Pearson product moment correlations and multiple linear regression analyses were performed, and significance levels were evaluated by the paired, 2-tailed t test. The difference between measured and real IOP was significantly dependent (P < .001) on CCT. The associations between IOP and corneal curvature or IOP and axial length were not statistically significant (P = .31). The association between IOP reading and CCT is shown in the "Dresdner correction table," which illustrates an approximately 1-mm Hg correction for every 25-microm deviation from a CCT of 550 microm. The correction values were positive as thickness decreased and negative as thickness increased. Central corneal thickness significantly affects IOP readings obtained by applanation tonometry according to the Goldmann principle. A correction of IOP readings by considering CCT according to the Dresdner correction table might be helpful for determining an accurate IOP value.

Concordance and interchangeability of biometric measurements of ocular axial length in patients awaiting cataract surgery.

PubMed

Martín-Serrano, María José; Roman-Ortiz, Carmen; Villa-Sáez, M Luz; Labrador-Castellanos, M Purificación; Blanco-Carrasco, Rosario; Lozano-Ballesteros, Felicidad; Pedraza-Martín, Carmen; José-Herrero, M Teresa San; López-Ropero, Ana M; Tenías Burillo, José María

2014-01-01

To estimate in patients awaiting cataract surgery the concordance and interchangeability of axial eye length measurements performed with the aid of various biometric methods (optical or ultrasonic) by different operators (nurses) at different times during the period prior to surgery. We selected 182 consecutive eyes from 91 patients.Ocular axial length was measured with the aid of 2 methods (IOLMaster® and Ocuscan®) by 9 randomly allocated technicians at 2 different times during the waiting period. The concordance between measurements was evaluated by means of the intraclass correlation coefficient (ICC); the interchangeability of the results was assessed with Bland Altman plots and Passing and Bablok regression. The measurements were consistent between biometric methods (ICC 0.975, 95% confidence interval [CI] 0.968 to 0.980) and measurement dates (ICC 0.996, 95% CI 0.995 to 0.997). Interobserver agreement was more heterogeneous (ICC range 0.844 to 0.998). No systematic errors were observed among the various biometric methods and measurement dates. Because measurement of axial length in phakic patients may be technician-dependent, the technician's experience should be noted in the protocols of ophthalmology services.

Supersonic axial-force characteristics of a rectangular-box cavity with various length-to-depth ratios in a flat plate

NASA Technical Reports Server (NTRS)

Blair, A. B., Jr.; Stallings, R. L., Jr.

1986-01-01

A wind-tunnel investigation has been conducted at Mach numbers of 1.50, 2.16, and 2.86 to obtain axial-force data on a metric rectangular-box cavity with various length-to-depth ratios. The model was tested at angles of attack from -4 deg to -2 deg. The results are summarized to show variations in cavity axial-force coefficient for deep- and shallow-cavity configurations with detached and attached cavity flow fields, respectively. The results of the investigation indicate that for a wide range of cavity lengths and depths, good correlations of the cavity axial-force coefficients (based on cavity rear-face area) are obtained when these coefficients are plotted as a function of cavity length-to-depth ratio. Abrupt increases in the cavity axial-force coefficients at an angle of attack of 0 deg. reflect the transition from an open (detached) cavity flow field to a closed (attached) cavity flow field. Cavity length-to-depth ratio is the dominant factor affecting the switching of the cavity flow field from one type to the other. The type of cavity flow field (open or closed) is not dependent on the test angles of attack except near the critical value of length-to-depth ratio.

The relationship of birth weight, gestational age, and postmenstrual age with ocular biometry parameters in premature infants.

PubMed

Ozdemir, Ozdemir; Tunay, Zuhal Ozen; Acar, Damla Erginturk; Erol, Muhammet Kazım; Sener, Ender; Acar, Ugur

2015-01-01

To analyze ocular biometry parameters and evaluate their relationship with gestational age, birth weight, and postmenstrual age in prematurely born infants. The right eyes of 361 premature infants born before the 36th gestational week were evaluated. Birth weight, gestational week, and gender were recorded. An A-scan Biometer was used for obtaining axial measurements, including anterior chamber depth, lens thickness, vitreous length, and total axial length. Gestational age and birth weight values ranged from 23 to 36 weeks and from 560 to 2,670 g, respectively. The mean gestational age and birth weight were 30.8 ± 2.8 weeks and 1,497.9 ± 483.6 g, respectively. During the first examination (4-5 weeks of postnatal age), birth weight and gestational age of the infants correlated significantly and positively with lens thickness, vitreous length, and axial length (r>0.5, p<0.001), but not with anterior chamber depth (r<0.5). Increased vitreous and axial lengths correlated significantly with increasing postmenstrual age of the infants (r=0.669, p<0.001; r=0.845, p<0.001, respectively). Lens thickness, vitreous length, and axial length, but not anterior chamber depth, were significantly correlated with birth weight and gestational age. All four parameters increased with increasing postmenstrual age, with higher correlations for vitreous and axial lengths than for anterior chamber depth and lens thickness. It was concluded that axial elongation resulted primarily from increasing posterior chamber length.

Vergence analysis reveals the influence of axial distances on accommodation with age and axial ametropia.

PubMed

Davies, Leon N; Dunne, Mark C M; Gibson, George A; Wolffsohn, James S

2010-07-01

Despite numerous investigations, the aetiology and mechanism of accommodation and presbyopia remains equivocal. Using Gaussian first-order ray tracing calculations, we examine the contribution that ocular axial distances make to the accommodation response. Further, the influence of age and ametropia are also considered. The data show that all changes in axial distances during accommodation reduce the accommodation response, with the reduction in anterior chamber depth contributing most to this overall attenuation. Although the total power loss due to the changes in axial distances remained constant with increasing age, hyperopes exhibited less accommodation than myopes. The study, therefore, enhances our understanding of biometric accommodative changes and demonstrates the utility of vergence analysis in the assessment of accommodation.

What changed during the axial age: Cognitive styles or reward systems?

PubMed Central

Baumard, Nicolas; Hyafil, Alexandre; Boyer, Pascal

2015-01-01

The ‘Axial Age’ (500–300 BCE) refers to the period during which most of the main religious and spiritual traditions emerged in Eurasian societies. Although the Axial Age has recently been the focus of increasing interest,1-5 its existence is still very much in dispute. The main reason for questioning the existence of the Axial Age is that its nature, as well as its spatial and temporal boundaries, remain very much unclear. The standard approach to the Axial Age defines it as a change of cognitive style, from a narrative and analogical style to a more analytical and reflective style, probably due to the increasing use of external memory tools. Our recent research suggests an alternative hypothesis, namely a change in reward orientation, from a short-term materialistic orientation to a long-term spiritual one.6 Here, we briefly discuss these 2 alternative definitions of the Axial Age. PMID:27066164

Association of Bruch's membrane opening and optic disc morphology to axial length and visual field defects in eyes with primary open-angle glaucoma.

PubMed

Nakanishi, Hideo; Suda, Kenji; Yoshikawa, Munemitsu; Akagi, Tadamichi; Kameda, Takanori; Ikeda, Hanako Ohashi; Yokota, Satoshi; Kurimoto, Yasuo; Tsujikawa, Akitaka

2018-03-01

To examine the morphology of Bruch's membrane opening (BMO), optic disc, and peripapillary atrophy (PPA) by scanning laser ophthalmoscopy (SLO) and spectral-domain optical coherence tomography (SD-OCT), and to determine their association with the axial length and visual field defects. This was a cross-sectional study of 94 eyes of 56 subjects; 77 eyes were diagnosed with primary open-angle glaucoma and 17 eyes as normal. The margins of the optic disc were determined in the SLO images, and that of the BMO in the SD-OCT images. The ovality and area of the BMO and the optic disc were measured. The beta and gamma-PPA areas were also measured. The association of each parameter with the axial length and the mean deviation (MD) of the visual field tests was determined by generalized estimating equations (GEEs). The optic disc ovality was associated with the axial length and the MD (β = -0.47, P = 7.6 × 10 -4 and β = 0.12, P = 0.040). The BMO ovality was not significantly associated with the axial length and the MD. The BMO area was associated with the axial length (β = 0.30, P = 0.029). A larger BMO area was associated with a thinner BMO-based neuroretinal rim width (BMO-MRW) after adjustments for the MD (β = -0.30, P = 2.1 × 10 -4 ). The beta- and gamma-PPA areas were associated with the axial length (β = 0.50, P = 7.4 × 10 -5 and β = 0.62, P = 4.2 × 10 -6 ). The optic disc ovality was associated with both the axial length and MD, whereas BMO ovality was not. Attention should be paid to the influence of the axial length-related enlargement of the BMO.

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

PubMed Central

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F.

2015-01-01

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length. PMID:26328984

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length.

PubMed

Liu, Wenzhong; Yi, Ji; Chen, Siyu; Jiao, Shuliang; Zhang, Hao F

2015-09-01

Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (small ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as -0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31 μl/min among four wild-type rats. The authors' measured flow rates were consistent with results in the literature. By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.

Measuring retinal blood flow in rats using Doppler optical coherence tomography without knowing eyeball axial length

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Wenzhong; Yi, Ji; Chen, Siyu

Purpose: Doppler optical coherence tomography (OCT) is widely used for measuring retinal blood flow. Existing Doppler OCT methods require the eyeball axial length, in which empirical values are usually used. However, variations in the axial length can create a bias unaccounted for in the retinal blood flow measurement. The authors plan to develop a Doppler OCT method that can measure the total retinal blood flow rate without requiring the eyeball axial length. Methods: The authors measured the retinal blood flow rate using a dual-ring scanning protocol. The small and large scanning rings entered the eye at different incident angles (smallmore » ring: 4°; large ring: 6°), focused on different locations on the retina, and detected the projected velocities/phase shifts along the probing beams. The authors calculated the ratio of the projected velocities between the two rings, and then used this ratio to estimate absolute flow velocity. The authors tested this method in both Intralipid phantoms and in vivo rats. Results: In the Intralipid flow phantom experiments, the preset and measured flow rates were consistent with the coefficient of determination as 0.97. Linear fitting between preset and measured flow rates determined the fitting slope as 1.07 and the intercept as −0.28. In in vivo rat experiments, the measured average total retinal blood flow was 7.02 ± 0.31μl/min among four wild-type rats. The authors’ measured flow rates were consistent with results in the literature. Conclusions: By using a dual-ring scanning protocol with carefully controlled incident angle difference between the two scanning rings in Doppler OCT, the authors demonstrated that it is feasible to measure the absolute retinal blood flow without knowing the eyeball axial length.« less

Tyre contact length on dry and wet road surfaces measured by three-axial accelerometer

NASA Astrophysics Data System (ADS)

Matilainen, Mika; Tuononen, Ari

2015-02-01

We determined the tyre contact length on dry and wet roads by measuring the accelerations of the inner liner with a three-axial accelerometer. The influence of the tyre pressure, driving velocity, and tread depth on the contact length was studied in both types of road surface conditions. On dry asphalt the contact length was almost constant, regardless of the driving velocity. On wet asphalt the presence of water could be detected even at low driving velocities (e.g. 20 km/h for a worn tyre) as the contact length began to decrease from that found in the dry asphalt situation. In addition to improving the performance of active safety systems and driver warning systems, the contact length information could be beneficial for classifying and studying the aquaplaning behaviour of tyres.

Axial length variation impacts on retinal vessel density and foveal avascular zone area measurement using optical coherence tomography angiography

NASA Astrophysics Data System (ADS)

Sampson, Danuta M.; Gong, Peijun; An, Di; Menghini, Moreno; Hansen, Alex; Mackey, David A.; Sampson, David D.; Chen, Fred K.

2017-04-01

We examined the impact of axial length on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurement using optical coherence tomography angiography. The SRVD and FAZA were quantified before and after correction for magnification error associated with axial length variation. Although SRVD did not differ before and after correction for magnification error in the parafoveal region, change in foveal SRVD and FAZA were significant. This has implications for clinical trials outcome in diseased eyes where significant capillary dropout may occur in the parafovea.

Ocular higher-order aberrations and axial eye growth in young Hong Kong children.

PubMed

Lau, Jason K; Vincent, Stephen J; Collins, Michael J; Cheung, Sin-Wan; Cho, Pauline

2018-04-30

This retrospective longitudinal analysis aimed to investigate the association between ocular higher-order aberrations (HOAs) and axial eye growth in Hong Kong children. Measures of axial length and ocular HOAs under cycloplegia were obtained annually over a two-year period from 137 subjects aged 8.8 ± 1.4 years with mean spherical equivalent refraction of -2.04 ± 2.38 D. A significant negative association was observed between the RMS of total HOAs and axial eye growth (P = 0.03), after adjusting for other significant predictors of axial length including age, sex and refractive error. Similar negative associations with axial elongation were found for the RMS of spherical aberrations ([Formula: see text] and [Formula: see text] combined) (P = 0.037). Another linear mixed model also showed that greater levels of vertical trefoil [Formula: see text], primary spherical aberration [Formula: see text] and negative oblique trefoil [Formula: see text] were associated with slower axial elongation and longer axial length (all P < 0.05). These findings support the potential role of HOAs, image quality and a vision-dependent mechanism in childhood eye growth.

Rapid, Accurate, and Non-Invasive Measurement of Zebrafish Axial Length and Other Eye Dimensions Using SD-OCT Allows Longitudinal Analysis of Myopia and Emmetropization

PubMed Central

Collery, Ross F.; Veth, Kerry N.; Dubis, Adam M.; Carroll, Joseph; Link, Brian A.

2014-01-01

Refractive errors in vision can be caused by aberrant axial length of the eye, irregular corneal shape, or lens abnormalities. Causes of eye length overgrowth include multiple genetic loci, and visual parameters. We evaluate zebrafish as a potential animal model for studies of the genetic, cellular, and signaling basis of emmetropization and myopia. Axial length and other eye dimensions of zebrafish were measured using spectral domain-optical coherence tomography (SD-OCT). We used ocular lens and body metrics to normalize and compare eye size and relative refractive error (difference between observed retinal radial length and controls) in wild-type and lrp2 zebrafish. Zebrafish were dark-reared to assess effects of visual deprivation on eye size. Two relative measurements, ocular axial length to body length and axial length to lens diameter, were found to accurately normalize comparisons of eye sizes between different sized fish (R2 = 0.9548, R2 = 0.9921). Ray-traced focal lengths of wild-type zebrafish lenses were equal to their retinal radii, while lrp2 eyes had longer retinal radii than focal lengths. Both genetic mutation (lrp2) and environmental manipulation (dark-rearing) caused elongated eye axes. lrp2 mutants had relative refractive errors of −0.327 compared to wild-types, and dark-reared wild-type fish had relative refractive errors of −0.132 compared to light-reared siblings. Therefore, zebrafish eye anatomy (axial length, lens radius, retinal radius) can be rapidly and accurately measured by SD-OCT, facilitating longitudinal studies of regulated eye growth and emmetropization. Specifically, genes homologous to human myopia candidates may be modified, inactivated or overexpressed in zebrafish, and myopia-sensitizing conditions used to probe gene-environment interactions. Our studies provide foundation for such investigations into genetic contributions that control eye size and impact refractive errors. PMID:25334040

Longitudinal changes in corneal curvature and its relationship to axial length in the Correction of Myopia Evaluation Trial (COMET) cohort.

PubMed

Scheiman, Mitchell; Gwiazda, Jane; Zhang, Qinghua; Deng, Li; Fern, Karen; Manny, Ruth E; Weissberg, Erik; Hyman, Leslie

2016-01-01

To describe longitudinal changes in corneal curvature (CC) and axial length (AL) over 14 years, and to explore the relationship between AL and CC, and the axial length/corneal radius (AL/CR) ratio. In total 469, 6 to <12-year-old, children were enrolled in COMET. Measurements of refractive error, CC (D), CR (mm), and ocular component dimensions including AL were gathered annually. Linear mixed models were used to evaluate longitudinal changes adjusting for covariates (gender, ethnicity, lens type, baseline age and baseline refraction). The Pearson correlation coefficient between AL and CC was computed at each visit. There was a slight but significant (p<0.0001) flattening in CC over 14 years. At all visits females had significantly steeper CC than males (overall difference=0.53 D, p<0.0001). Caucasians had the steepest CC, and Hispanics the flattest (p=0.001). The correlation between AL and CC was -0.70 (p<0.0001) at baseline (mean age=9.3 years) and decreased to -0.53 (p<0.0001) at the 14-year visit (mean age=24.1 years). The average AL/CR ratio was 3.15 at baseline and increased to 3.31 at the 14-year visit. The correlation between the magnitude of myopia and AL/CR ratio was significantly higher (p<0.0001) at each visit than the correlation between myopia and AL alone. Differences in average corneal curvature by age, gender, and ethnicity observed in early childhood remain consistent as myopia progresses and stabilizes. This study also demonstrates increases in the AL/CR ratio as myopia progresses and then stabilizes, supporting observations from previous cross-sectional data. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Analysis of corneal astigmatism with NIDEK axial length scan in caucasian cataract surgery candidates.

PubMed

Duman, R; Duman, R; Cetinkaya, E; Sabaner, M C; Inan, S; Doğan, M; Doğan, I

2018-04-01

The aim of the study was to analyze and quantify the pattern of corneal astigmatism in Caucasian cataract surgery patients using a new optical biometer (axial length [AL] Scan, NIDEK Co., Gamagori, Japan). The datasets of cataract surgery patients acquired between March 1, 2014, and April 15, 2016, were collected and analyzed. The corneal power (flat keratometry, steep keratometry, and mean keratometry), negative cylinder power, and axis of astigmatism were recorded. Keratometry values were optically measured by optical low coherence interferometry (AL-Scan, NIDEK Co., Ltd.,) before cataract extraction. The study comprised 1233 eyes of 838 consecutive cataract candidates with a mean age of 66.8 ± 10.7 years (range 40-97 years). The mean keratometry value and corneal astigmatism were 43.69 ± 1.61 D and 0.84 ± 0.70 D, respectively. Corneal astigmatism of 1.00 D or greater was found in 344 eyes (27.9%), and 548 eyes (44.4%) had against-the-rule astigmatism. A trend toward decreasing J0 and J45 with age was found by linear regression models. The per-year increase in age was associated with a J0 and J45 decrease of 0.002 D and 0.001D, respectively. This study provides the distribution of astigmatism axis and power for cataract patients in age subsets from Turkey.

Relations between age, weight, refractive error and eye shape by computerized tomography in children.

PubMed

Song, Ha Tae; Kim, Young Jun; Lee, Soo Jung; Moon, Yeon Sung

2007-09-01

To investigate relationships between age, weight, refractive error, and morphologic changes in children's eyes by computerized tomography (CT). Of the 772 eyes of 386 patients under the age of 20 years, who visited our Department of Ophthalmology between January 2005 to August 2006 and underwent CT of the orbit, 406 eyes of 354 patients with clear CT images and normal eyeball contour were enrolled in the present retrospective study. The axial lengths, widths, horizontal and vertical lengths, refractive errors, and body weight of eyes were measured, and relationship between these parameters were investigated. Axial length was found to correlate significantly with eye width (r=0.914), and in emmetropic eyes and myopic eyes, axial lengths and widths were found to increase as age and body weight increased. Axial lengths increased rapidly until age 10, and then increased slowly. In emmetropic eyes, widths/axial lengths increased with age, but in myopic eyes these decreased as age or severity of myopia increased. Moreover, as age increased, the myopic population and severity also increased. The axial length was longer in case of myopia compared to emmetropia in all age groups and there was almost no difference in the increase rate of axial length by the age of myopia and emmetropia. However, the width was wider in case of myopia compared to emmetropia in all age groups and the increase rate of width in myopia by age was smaller than that of emmetropia. Myopia showed decreasing rate of width/axial length with increase of age, from 1.004 in 5 years to 0.971 in 20 years. However, emmetropia showed increasing rate of width/axial length with increase of age, from 0.990 in 5 years to 1.006 in 20 years.

Relations between Age, Weight, Refractive Error and Eye Shape by Computerized Tomography in Children

PubMed Central

Song, Ha Tae; Kim, Young Jun; Lee, Soo Jung

2007-01-01

Purpose To investigate relationships between age, weight, refractive error, and morphologic changes in children's eyes by computerized tomography (CT). Methods Of the 772 eyes of 386 patients under the age of 20 years, who visited our Department of Ophthalmology between January 2005 to August 2006 and underwent CT of the orbit, 406 eyes of 354 patients with clear CT images and normal eyeball contour were enrolled in the present retrospective study. The axial lengths, widths, horizontal and vertical lengths, refractive errors, and body weight of eyes were measured, and relationship between these parameters were investigated. Results Axial length was found to correlate significantly with eye width (r=0.914), and in emmetropic eyes and myopic eyes, axial lengths and widths were found to increase as age and body weight increased. Axial lengths increased rapidly until age 10, and then increased slowly. In emmetropic eyes, widths / axial lengths increased with age, but in myopic eyes these decreased as age or severity of myopia increased. Moreover, as age increased, the myopic population and severity also increased. Conclusions The axial length was longer in case of myopia compared to emmetropia in all age groups and there was almost no difference in the increase rate of axial length by the age of myopia and emmetropia. However, the width was wider in case of myopia compared to emmetropia in all age groups and the increase rate of width in myopia by age was smaller than that of emmetropia. Myopia showed decreasing rate of width/axial length with increase of age, from 1.004 in 5 years to 0.971 in 20 years. However, emmetropia showed increasing rate of width/axial length with increase of age, from 0.990 in 5 years to 1.006 in 20 years. PMID:17804923

Axial Movements and Length Changes of the Human Lower Esophageal Sphincter During Respiration and Distension-induced Secondary Peristalsis Using Functional Luminal Imaging Probe

PubMed Central

Liao, Donghua; Lottrup, Christian; Fynne, Lotte; McMahon, Barry P; Krogh, Klaus; Drewes, Asbjørn M; Zhao, Jingbo; Gregersen, Hans

2018-01-01

Background/Aims Efficient transport through the esophago-gastric junction (EGJ) requires synchronized circular and longitudinal muscle contraction of the esophagus including relaxation of the lower esophageal sphincter (LES). However, there is a scarcity of technology for measuring esophagus movements in the longitudinal (axial) direction. The aim of this study is to develop new analytical tools for dynamic evaluation of the length change and axial movement of the human LES based on the functional luminal imaging probe (FLIP) technology and to present normal signatures for the selected parameters. Methods Six healthy volunteers without hiatal hernia were included. Data were analyzed from stepwise LES distensions at 20, 30, and 40 mL bag volumes. The bag pressure and the diameter change were used for motion analysis in the LES. The cyclic bag pressure frequency was used to distinguish dynamic changes of the LES induced by respiration and secondary peristalsis. Results Cyclic fluctuations of the LES were evoked by respiration and isovolumetric distension, with phasic changes of bag pressure, diameter, length, and axial movement of the LES narrow zone. Compared to the respiration-induced LES fluctuations, peristaltic contractions increased the contraction pressure amplitude (P < 0.001), shortening (P < 0.001), axial movement (P < 0.001), and diameter change (P < 0.01) of the narrow zone. The length of the narrow zone shortened as function of the pressure increase. Conclusions FLIP can be used for evaluation of dynamic length changes and axial movement of the human LES. The method may shed light on abnormal longitudinal muscle activity in esophageal disorders. PMID:29605981

Association of Body Length with Ocular Parameters in Mice

PubMed Central

Chakraborty, Ranjay; Park, Han na; Tan, Christopher C.; Weiss, Paul; Prunt, Megan C.; Pardue, Machelle T.

2017-01-01

Purpose To determine the association between changes in body length with ocular refraction, corneal radii, axial length, and lens thickness in two different mouse strains. Methods Body length, ocular refraction, corneal radii, axial length, and lens thickness were measured for two inbred mouse strains: 129S1/SvJ (n=7) and C57BL/6J (n=10) from 4 to 12 weeks of age. Body length, from tip of nose to base of tail was obtained using a digital camera. Biometric parameters, corneal radii and refractions were measured using spectral-domain optical coherence tomography, automated keratometry and infrared photorefraction, respectively. A mixed model ANOVA was performed to examine the changes in ocular parameters as a function of body length and strain in mice controlling for age, gender and weight over time. Results C57BL/6J mice had significantly longer body length (average body length at 10 weeks, 8.60 ± 0.06 cm) compared 129S1/SvJ mice (8.31 ± 0.05 cm) during development (p<0.001). C57BL/6J mice had significantly hyperopic refractions compared to 129S1/SvJ mice across age (mean refraction at 10 weeks, 129S1/SvJ: +0.99 ± 0.44 D versus C57BL/6J: +6.24 ± 0.38 D, p<0.001). Corneal radius of curvature, axial length and lens thickness (except 10 weeks lens thickness) were similar between the two strains throughout the measurement. In the mixed model ANOVA, changes in body length showed an independent and significant association with the changes in refraction (p=0.002) and corneal radii (p=0.016) for each mouse strain. No significant association was found between the changes in axial length (p=0.925) or lens thickness (p=0.973) as a function of body length and strain. Conclusions Changes in body length are significantly associated with the changes in ocular refraction and corneal radii in different mouse strains. Future studies are needed to determine if the association between body length and ocular refraction are related to changes in corneal curvature in mice. PMID

Effect on fan flow characteristics of length and axial location of a cascade thrust reverser

NASA Technical Reports Server (NTRS)

Dietrich, D. A.

1975-01-01

A series of static tests were conducted on a model fan with a diameter of 14.0 cm to determine the fan operating characteristics, the inlet static pressure contours, the fan-exit total and static pressure contours, and the fan-exit pressure distortion parameters associated with the installation of a partial-circumferential-emission cascade thrust reverser. The tests variables included the cascade axial length, the axial location of the reverser, and the type of fan inlet. It was shown that significant total and static pressure distortions were produced in the fan aft duct, and that some configurations induced a static pressure distortion at the fan face. The amount of flow passed by the fan and the level of the flow distortions were dependent upon all the variables tested.

Axial Length Variation Impacts on Superficial Retinal Vessel Density and Foveal Avascular Zone Area Measurements Using Optical Coherence Tomography Angiography.

PubMed

Sampson, Danuta M; Gong, Peijun; An, Di; Menghini, Moreno; Hansen, Alex; Mackey, David A; Sampson, David D; Chen, Fred K

2017-06-01

To evaluate the impact of image magnification correction on superficial retinal vessel density (SRVD) and foveal avascular zone area (FAZA) measurements using optical coherence tomography angiography (OCTA). Participants with healthy retinas were recruited for ocular biometry, refraction, and RTVue XR Avanti OCTA imaging with the 3 × 3-mm protocol. The foveal and parafoveal SRVD and FAZA were quantified with custom software before and after correction for magnification error using the Littman and the modified Bennett formulae. Relative changes between corrected and uncorrected SRVD and FAZA were calculated. Forty subjects were enrolled and the median (range) age of the participants was 30 (18-74) years. The mean (range) spherical equivalent refractive error was -1.65 (-8.00 to +4.88) diopters and mean (range) axial length was 24.42 mm (21.27-28.85). Images from 13 eyes were excluded due to poor image quality leaving 67 for analysis. Relative changes in foveal and parafoveal SRVD and FAZA after correction ranged from -20% to +10%, -3% to +2%, and -20% to +51%, respectively. Image size correction in measurements of foveal SRVD and FAZA was greater than 5% in 51% and 74% of eyes, respectively. In contrast, 100% of eyes had less than 5% correction in measurements of parafoveal SRVD. Ocular biometry should be performed with OCTA to correct image magnification error induced by axial length variation. We advise caution when interpreting interocular and interindividual comparisons of SRVD and FAZA derived from OCTA without image size correction.

Accurate aging of juvenile salmonids using fork lengths

USGS Publications Warehouse

Sethi, Suresh; Gerken, Jonathon; Ashline, Joshua

2017-01-01

Juvenile salmon life history strategies, survival, and habitat interactions may vary by age cohort. However, aging individual juvenile fish using scale reading is time consuming and can be error prone. Fork length data are routinely measured while sampling juvenile salmonids. We explore the performance of aging juvenile fish based solely on fork length data, using finite Gaussian mixture models to describe multimodal size distributions and estimate optimal age-discriminating length thresholds. Fork length-based ages are compared against a validation set of juvenile coho salmon, Oncorynchus kisutch, aged by scales. Results for juvenile coho salmon indicate greater than 95% accuracy can be achieved by aging fish using length thresholds estimated from mixture models. Highest accuracy is achieved when aged fish are compared to length thresholds generated from samples from the same drainage, time of year, and habitat type (lentic versus lotic), although relatively high aging accuracy can still be achieved when thresholds are extrapolated to fish from populations in different years or drainages. Fork length-based aging thresholds are applicable for taxa for which multiple age cohorts coexist sympatrically. Where applicable, the method of aging individual fish is relatively quick to implement and can avoid ager interpretation bias common in scale-based aging.

Ocular growth in the fetus. 1. Comparative study of axial length and biometric parameters in the fetus.

PubMed

Denis, D; Righini, M; Scheiner, C; Volot, F; Boubli, L; Dezard, X; Vola, J; Saracco, J B

1993-01-01

The knowledge of ocular growth during fetal life, when compared with other fetal biometric parameters, could not only provide a better definition of malformation syndromes but could also give a better understanding of certain pathological processes in premature babies and in newborns. As the literature concerning prenatal ocular dimensions contains few data, the aim of this study was to measure the axial length of the globe (AL) in fetuses and compare this measurement with their gestational age, weight, height, head circumference (HC) and thoracic circumference (TC) in order to compile a reference table. In the present study, 76 globes from 38 fetuses (18-41 weeks gestational age) from the Department of Pathology (Timone University Hospital, Marseille) were examined. Ultrasonography A and B were used to measure the AL, and a pathological examination determined fetal weight, HC, TC and height. We were interested to find out which of the parameters studied would give the best correlation with ocular growth. Statistical analysis showed that HC remained the most discriminant factor and correlated best with ocular growth. We thus obtained an equation for ocular size according to HC that could serve as a basis for detecting pre- or postnatal ocular defects.

Baseline peripheral refractive error and changes in axial refraction during one year in a young adult population.

PubMed

Hartwig, Andreas; Charman, William Neil; Radhakrishnan, Hema

2016-01-01

To determine whether the initial characteristics of individual patterns of peripheral refraction relate to subsequent changes in refraction over a one-year period. 54 myopic and emmetropic subjects (mean age: 24.9±5.1 years; median 24 years) with normal vision were recruited and underwent conventional non-cycloplegic subjective refraction. Peripheral refraction was also measured at 5° intervals over the central 60° of horizontal visual field, together with axial length. After one year, measurements of subjective refraction and axial length were repeated on the 43 subjects who were still available for examination. In agreement with earlier studies, higher myopes tended to show greater relative peripheral hyperopia. There was, however, considerable inter-subject variation in the pattern of relative peripheral refractive error (RPRE) at any level of axial refraction. Across the group, mean one-year changes in axial refraction and axial length did not differ significantly from zero. There was no correlation between changes in these parameters for individual subjects and any characteristic of their RPRE. No evidence was found to support the hypothesis that the pattern of RPRE is predictive of subsequent refractive change in this age group. Copyright © 2015 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

Age Group Comparisons of TENS Response Among Individuals With Chronic Axial Low Back Pain.

PubMed

Simon, Corey B; Riley, Joseph L; Fillingim, Roger B; Bishop, Mark D; George, Steven Z

2015-12-01

Chronic low back pain (CLBP) is a highly prevalent and disabling musculoskeletal pain condition among older adults. Transcutaneous electrical nerve stimulation (TENS) is commonly used to treat CLBP, however response to TENS in older adults compared with younger adults is untested. In a dose-response study stratified by age, 60 participants with axial CLBP (20 young, 20 middle-aged, 20 older) received four 20-minute sessions of high-frequency high-intensity TENS over a 2- to 3-week period in a laboratory-controlled setting. Experimental measures of pain sensitivity (mechanical pressure pain detection threshold) and central pain excitability (phasic heat temporal summation and heat aftersensations) were assessed before and after TENS. Episodic or immediate axial CLBP relief was assessed after TENS via measures of resting pain, movement-evoked-pain, and self-reported disability. Cumulative or prolonged axial CLBP relief was assessed by comparing daily pain reports across sessions. Independent of age, individuals experienced episodic increase in the pressure pain detection threshold and reduction in aftersensation after TENS application. Similarly, all groups, on average, experienced episodic axial CLBP relief via improved resting pain, movement-evoked pain, and disability report. Under this design, no cumulative effect was observed as daily pain did not improve for any age group across the 4 sessions. However, older adults received higher TENS amplitude across all sessions to achieve TENS responses similar to those in younger adults. These findings suggest that older adults experience similar episodic axial CLBP relief to that of younger individuals after high-frequency, high-intensity TENS when higher dose parameters are used. This study examined age group differences in experimental and axial CLBP response to TENS, delivered under the current recommended parameters of strong, but tolerable amplitude. Older adults had comparable TENS response although at higher TENS

Axial Length Measurement Failure Rates With Biometers Using Swept-Source Optical Coherence Tomography Compared to Partial-Coherence Interferometry and Optical Low-Coherence Interferometry.

PubMed

McAlinden, Colm; Wang, Qinmei; Gao, Rongrong; Zhao, Weiqi; Yu, Ayong; Li, Yu; Guo, Yan; Huang, Jinhai

2017-01-01

To compare a new swept-source optical coherence tomography (SSOCT)-based biometer (OA-2000) with the IOLMaster v5.4 (partial-coherence interferometry) and Aladdin (optical low-coherence interferometry) biometers in terms of axial length measurement and failure rate in eyes with cataract. Reliability study. A total of 377 eyes of 210 patients were scanned with the 3 biometers in a random order. For each biometer, the number of unobtainable axial length measurements was recorded and grouped as per the type and severity of cataract based on the Lens Opacities Classification System III by the same experienced ophthalmologist. The Bland-Altman limits-of-agreement (LoA) method was used to assess the agreement in axial length measurements between the 3 biometers. The failure rate was 0 eyes (0%) with the OA-2000, 136 eyes (36.07%) with the IOLMaster, and 51 eyes (13.53%) with the Aladdin. χ 2 analyses indicated a significant difference in failure rate between all 3 devices (P < .001). Logistic regression analysis highlighted a statistically significant trend of higher failure rates with increasing severity of nuclear, cortical, and posterior subcapsular cataracts. Bland-Altman statistics indicated small mean differences and narrow LoA (OA-2000 vs IOLMaster -0.09 to 0.08 mm; OA-2000 vs Aladdin -0.10 to 0.07 mm; IOLMaster vs Aladdin -0.05 to 0.04 mm). The OA-2000, a new SSOCT-based biometer, outperformed both the IOLMaster and Aladdin biometers in very advanced cataracts of various morphologies. The use of SSOCT technology may be the reason for the improved performance of the OA-2000 and may lead to this technology becoming the gold standard for the measurement of axial length. Copyright © 2016 Elsevier Inc. All rights reserved.

Age Group Comparisons of TENS Response among Individuals with Chronic Axial Low Back Pain

PubMed Central

Simon, Corey B.; Riley, Joseph L.; Fillingim, Roger B.; Bishop, Mark D.; George, Steven Z.

2015-01-01

Chronic low back pain (CLBP) is a highly prevalent and disabling musculoskeletal pain condition among older adults. Transcutaneous electrical nerve stimulation (TENS) is commonly used to treat CLBP, however, TENS response for older adults compared to younger adults is untested. In a dose-response study stratified by age, sixty participants with axial CLBP (20 young, 20 middle-aged, 20 older) received four 20-minute sessions of high frequency, high intensity TENS over a two to three-week period in a laboratory-controlled setting. Experimental measures of pain sensitivity (mechanical pressure pain detection threshold, PPT) and central pain excitability (phasic heat temporal summation, TS; heat aftersensations, AS) were assessed before and after TENS. Episodic or immediate axial CLBP relief was assessed after TENS via measures of resting pain, movement-evoked-pain, and self-reported disability. Cumulative or prolonged axial CLBP relief was assessed by comparing daily pain report across sessions. Independent of age, individuals experienced episodic increase in PPT and reduction in AS following TENS application. Similarly, all groups, on average, experienced episodic axial CLBP relief via improved resting pain, movement-evoked pain, and disability report. Under this design, no cumulative effect was observed as daily pain did not improve for any age group across the four sessions. However, older adults received higher TENS amplitude across all sessions in achieving similar TENS responses to younger adults. These findings suggest that older adults experience similar episodic axial CLBP relief as younger individuals following high frequency, high intensity TENS when higher dosage parameters are used. PMID:26342650

Direct determination of minority carrier diffusion lengths at axial GaAs nanowire p-n junctions.

PubMed

Gutsche, Christoph; Niepelt, Raphael; Gnauck, Martin; Lysov, Andrey; Prost, Werner; Ronning, Carsten; Tegude, Franz-Josef

2012-03-14

Axial GaAs nanowire p-n diodes, possibly one of the core elements of future nanowire solar cells and light emitters, were grown via the Au-assisted vapor-liquid-solid mode, contacted by electron beam lithography, and investigated using electron beam induced current measurements. The minority carrier diffusion lengths and dynamics of both, electrons and holes, were determined directly at the vicinity of the p-n junction. The generated photocurrent shows an exponential decay on both sides of the junction and the extracted diffusion lengths are about 1 order of magnitude lower compared to bulk material due to surface recombination. Moreover, the observed strong diameter-dependence is well in line with the surface-to-volume ratio of semiconductor nanowires. Estimating the surface recombination velocities clearly indicates a nonabrupt p-n junction, which is in essential agreement with the model of delayed dopant incorporation in the Au-assisted vapor-liquid-solid mechanism. Surface passivation using ammonium sulfide effectively reduces the surface recombination and thus leads to higher minority carrier diffusion lengths. © 2012 American Chemical Society

SCLERAL AND CHOROIDAL THICKNESS IN SECONDARY HIGH AXIAL MYOPIA.

PubMed

Shen, Ling; You, Qi Sheng; Xu, Xiaolin; Gao, Fei; Zhang, Zhibao; Li, Bin; Jonas, Jost B

2016-08-01

To assess differences in scleral and choroidal thickness between eyes with secondary high axial myopia caused by congenital glaucoma, eyes with primary high axial myopia, and nonhighly myopic eyes. The study consisted of 301 Chinese individuals with a mean age of 23.9 ± 22.6 years and mean axial length of 24.8 ± 4.2 mm. It included the "secondary highly myopic group" (SHMG) because of congenital glaucoma (n = 20 eyes; axial length >26.0 mm), the "primary highly myopic group" (PHMG) (n = 73; axial length >26.0 mm), and the remaining nonhighly myopic group (NHMG). The secondary highly myopic group versus the primary highly myopic group had significantly thinner sclera in the pars plana region (343 ± 71 μm versus 398 ± 83 μm; P = 0.006), whereas scleral thickness in other regions did not differ significantly between both highly myopic groups and was significantly thinner in both highly myopic groups than in the NHMG. Mean total scleral volume did not differ significantly (P > 0.20) between any group (SHMG: 659 ± 106 μm; PHMG: 667 ± 128 μm; NHMG: 626 ± 135 μm). Choroidal thickness was significantly thinner in both highly myopic groups than in the NHMG, with no significant differences between both highly myopic groups. Choroidal volume did not differ significantly (P > 0.40) between any of the groups (SHMG: 43 ± 12 μm; PHMG: 43 ± 13 μm; NHMG: 46 ± 17 μm). In secondary high axial myopia, the sclera gets thinner anterior and posterior to the equator; whereas in primary high axial myopia, scleral thinning is predominantly found posterior to the equator. Because volume of sclera and choroid did not differ between any group, scleral and choroidal thinning in myopia may be due to a rearrangement of tissue and not due to the new formation of tissue.

[One-year longitudinal change in parameters of myopic school children trained by a new accommodative training device--uncorrected visual acuity, refraction, axial length, accommodation, and pupil reaction].

PubMed

Watanabe, Kumiko; Hara, Naoto; Kimijima, Masumi; Kotegawa, Yasue; Ohno, Koji; Arimoto, Ako; Mukuno, Kazuo; Hisahara, Satoru; Horie, Hidenori

2012-10-01

School children with myopia were trained using a visual stimulation device that generated an isolated blur stimulus on a visual target, with a constant retinal image size and constant brightness. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and papillary reaction were measured to investigate the effectiveness of the training. There were 45 school children with myopia without any other ophthalmic diseases. The mean age of the children was 8.9 +/- 2.0 years (age range; 6-16)and the mean refraction was -1.56 +/- 0.58 D (mean +/- standard deviation). As a visual stimulus, a white ring on a black background with a constant ratio of visual target size to retinal image size, irrespective of the distance, was displayed on a liquid crystal display (LCD), and the LCD was quickly moved from a proximal to a distal position to produce an isolated blur stimulus. Training with this visual stimulus was carried out in the relaxation phase of accommodation. Uncorrected visual acuity, cycloplegic refraction, axial length, dynamic accommodation and pupillary reaction were investigated before training and every 3 months during the training. Of the 45 subjects, 42 (93%) could be trained for 3 consecutive months, 33 (73%) for 6 months, 23 (51%) for 9 months, and 21 (47%) for 12 months. The mean refraction decreased by 0.83 +/- 0.56 D (mean +/- standard deviation) and the mean axial length increased by 0.47 +/- 0.16 mm at 1 year, showing that the training bad some effect in improving the visual acuity. In the tests of the dynamic accommodative responses, the latency of the accommodative-phase decreased from 0.4 +/- 0.2 sec to 0.3 +/- 0.1 sec at 1 year, the gain of the accommodative-phase improved from 69.0 +/- 27.0% to 93.3 +/- 13.4%, the maximum speed of the accommodative-phase increased from 5.1 +/- 2.2 D/sec to 6.8 +/- 2.2 D/sec and the gain of the relaxation-phase significantly improved from 52.1 +/- 26.0% to 72.7 +/- 13.7% (corresponding t

The role of axial length-corneal radius of curvature ratio in refractive state categorization in a nigerian population.

PubMed

Iyamu, Eghosasere; Iyamu, Joy; Obiakor, Christian Izuchukwu

2011-01-01

The aim of this study was to investigate the association of axial length (AL)/corneal radius of curvature (CRC) ratio (AL/CRC) with spherical equivalent refractive state (SER) in young adults. A total of seventy (n = 70) subjects consisting of 31 males and 39 females participated in this study. Subjects were categorized into emmetropia, hyperopia and myopia using the spherical equivalent refraction. The axial length was measured with I-2100 A-Scan ultrasonography/Biometer (CIMA Technology, USA), the corneal radius of curvature with Bausch & Lomb H-135A (Bausch & Lomb Corp., USA), and the refractive state by static retinoscopy and subjective refraction. The mean AL, CRC and AL/CRC ratio of all subjects were 23.74 ± 0.70 mm, 7.84 ± 0.19 mm, and 3.03 ± 0.14, respectively. Myopes had significantly longer AL, steeper CRC and higher AL/CRC ratio than the emmetropes and hyperopes. There was statistically significant inverse correlation between AL and CRC (r = -0.53, P < 0.0001), SER (r = -0.64, P < 0.0001), and between SER and AL/CRC (r = -0.78, P < 0.0001). A significant positive correlation was found between CRC and SER (r = -0.69, P < 0.0001). The categorization of the refractive state of an individual is better done by using the AL/CRC ratio index.

Exploring the relationship between age and tenure with length of disability

PubMed Central

Young, Amanda E.; Pransky, Glenn

2015-01-01

Background The aging of the workforce, coupled with the changing nature of career tenure has raised questions about the impact of these trends on work disability. This study aimed to determine if age and tenure interact in relating to work disability duration. Methods Relationships were investigated using random effects models with 239,359 work disability claims occurring between 2008 and 2012. Results A 17‐day difference in the predicted length of disability was observed from ages 25 to 65. Tenure moderated the relationship between age and length of disability. At younger ages, the length of disability decreased as tenure increased, but at older age, the length of disability increased as tenure increased. Discussion Results indicate that although there is a relationship between length of disability and tenure, age makes a greater unique contribution to explaining variance in length of disability. Future research is needed to better understand why specifically age shows a strong relationship with length of disability and why that relationship varies with age. Am. J. Ind. Med. 58:974–987, 2015. © 2015 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc. PMID:26010587

Estimating age at a specified length from the von Bertalanffy growth function

USGS Publications Warehouse

Ogle, Derek H.; Isermann, Daniel A.

2017-01-01

Estimating the time required (i.e., age) for fish in a population to reach a specific length (e.g., legal harvest length) is useful for understanding population dynamics and simulating the potential effects of length-based harvest regulations. The age at which a population reaches a specific mean length is typically estimated by fitting a von Bertalanffy growth function to length-at-age data and then rearranging the best-fit equation to solve for age at the specified length. This process precludes the use of standard frequentist methods to compute confidence intervals and compare estimates of age at the specified length among populations. We provide a parameterization of the von Bertalanffy growth function that has age at a specified length as a parameter. With this parameterization, age at a specified length is directly estimated, and standard methods can be used to construct confidence intervals and make among-group comparisons for this parameter. We demonstrate use of the new parameterization with two data sets.

Age Determination by Back Length for African Savanna Elephants: Extending Age Assessment Techniques for Aerial-Based Surveys

PubMed Central

Trimble, Morgan J.; van Aarde, Rudi J.; Ferreira, Sam M.; Nørgaard, Camilla F.; Fourie, Johan; Lee, Phyllis C.; Moss, Cynthia J.

2011-01-01

Determining the age of individuals in a population can lead to a better understanding of population dynamics through age structure analysis and estimation of age-specific fecundity and survival rates. Shoulder height has been used to accurately assign age to free-ranging African savanna elephants. However, back length may provide an analog measurable in aerial-based surveys. We assessed the relationship between back length and age for known-age elephants in Amboseli National Park, Kenya, and Addo Elephant National Park, South Africa. We also compared age- and sex-specific back lengths between these populations and compared adult female back lengths across 11 widely dispersed populations in five African countries. Sex-specific Von Bertalanffy growth curves provided a good fit to the back length data of known-age individuals. Based on back length, accurate ages could be assigned relatively precisely for females up to 23 years of age and males up to 17. The female back length curve allowed more precise age assignment to older females than the curve for shoulder height does, probably because of divergence between the respective growth curves. However, this did not appear to be the case for males, but the sample of known-age males was limited to ≤27 years. Age- and sex-specific back lengths were similar in Amboseli National Park and Addo Elephant National Park. Furthermore, while adult female back lengths in the three Zambian populations were generally shorter than in other populations, back lengths in the remaining eight populations did not differ significantly, in support of claims that growth patterns of African savanna elephants are similar over wide geographic regions. Thus, the growth curves presented here should allow researchers to use aerial-based surveys to assign ages to elephants with greater precision than previously possible and, therefore, to estimate population variables. PMID:22028925

Engineering of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps

NASA Astrophysics Data System (ADS)

Yu, Yanzhong; Huang, Han; Zhou, Mianmian; Zhan, Qiwen

2018-01-01

Based on the radiation pattern from a sectional-uniform line source antenna, a three-dimensional (3D) focus engineering technique for the creation of multi-segmented light tunnel and flattop focus with designed axial lengths and gaps is proposed. Under a 4Pi focusing system, the fields radiated from sectional-uniform magnetic and electromagnetic current line source antennas are employed to generate multi-segmented optical tube and flattop focus, respectively. Numerical results demonstrate that the produced light tube and flattop focus remain homogeneous along the optical axis; and their lengths of the nth segment and the nth gap between consecutive segments can be easily adjusted and only depend on the sizes of the nth section and the nth blanking between adjacent sectional antennas. The optical tube is a pure azimuthally polarized field but for the flattop focus the longitudinal polarization is dominant on the optical axis. To obtain the required pupil plane illumination for constructing the above focal field with prescribed characteristics, the inverse problem of the antenna radiation field is solved. These peculiar focusing fields might find potential applications in multi-particle acceleration, multi-particle trapping and manipulation.

Axial Length/Corneal Radius of Curvature Ratio and Myopia in 3-Year-Old Children

PubMed Central

Foo, Valencia Hui Xian; Verkicharla, Pavan Kumar; Ikram, Mohammad Kamran; Chua, Sharon Yu Lin; Cai, Shirong; Tan, Chuen Seng; Chong, Yap-Seng; Kwek, Kenneth; Gluckman, Peter; Wong, Tien-Yin; Ngo, Cheryl; Saw, Seang-Mei; on behalf of the GUSTO study group

2016-01-01

Purpose This study investigated the association of axial length (AL) to corneal radius of curvature (CRC) ratio with spherical equivalent (SE) in a 3-year old Asian cohort. Methods Three-hundred forty-nine 3-year old Asian children from The Growing Up in Singapore towards Healthy Outcomes (GUSTO) birth cohort study underwent AL and CRC measurements with a noncontact ocular biometer and cycloplegic refraction using an autorefractor. The ratio of AL to CRC (AL/CRC) was calculated for all the participants, and subsequently AL, CRC, and AL/CRC were analyzed in relationship to SE. Results The SE showed better correlation with AL/CRC (Spearman's correlation coefficient, ρ = −0.53; 95% confidence interval [CI]: −0.66; −0.49; P < 0.001) compared to either AL or CRC alone ([ρ = −0.36; 95% CI: −0.51 to 0.51; P = 0.01] and [ρ = 0.05; 95% CI: −0.04 to 0.17; P = 0.34], respectively). Mean AL/CRC was 2.91 ± 0.06 among myopes and decreased to 2.79 ± 0.06 among hyperopes. Axial length to corneal radius of curvature was strongly correlated with SE in myopes (ρ = −0.78; 95% CI: −3.76; −0.79; P = < 0.001), but not in emmetropes and hyperopes ([ρ = −0.39; 95% CI: −10.73; −0.57; P = 0.01] and [ρ = −0.18; 95% CI: −17.28; 12.42; P = 0.38], respectively). Linear regression adjusted for gender and ethnicity showed a 0.74-diopter shift in SE towards myopia with every 0.1 increase in AL/CRC ratio (P < 0.001, r2 = 0.33). Conclusion The correlation between SE and AL/CRC is stronger than that between AL or CRC alone. This suggests that in a research setting, when cycloplegic refraction is difficult to perform on 3-year-old children, AL/CRC may be the next best reference for refractive error. Translational Relevance In the research setting, AL/CRC may be the next best reference for refractive error over AL alone when cycloplegic refraction is unavailable in 3-year old children. PMID:26929885

Romantic relationship development: The interplay between age and relationship length.

PubMed

Lantagne, Ann; Furman, Wyndol

2017-09-01

The present study explored how romantic relationship qualities develop with age and relationship length. Eight waves of data on romantic relationships were collected over 10.5 years during adolescence and early adulthood from a community-based sample in a Western U.S. city (100 males, 100 females; M age Wave 1 = 15.83). Measures of support, negative interactions, control, and jealousy were derived from interviews and questionnaire measures. Using multilevel modeling, main effects of age were found for jealousy, and main effects of relationship length were found for each quality. However, main effects were qualified by significant age by length interactions for each and every relationship quality. Short relationships increased in support with age. In comparison, long-term adolescent relationships were notable in that they were both supportive and turbulent, with elevated levels of support, negative interactions, control, and jealousy. With age, long-term relationships continued to have high levels of support, but decreased in negative interactions, control, and jealousy. Present findings highlight how the interplay between age and relationship length is key for understanding the development of romantic relationships. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Usefulness of telomere length in DNA from human teeth for age estimation.

PubMed

Márquez-Ruiz, Ana Belén; González-Herrera, Lucas; Valenzuela, Aurora

2018-03-01

Age estimation is widely used to identify individuals in forensic medicine. However, the accuracy of the most commonly used procedures is markedly reduced in adulthood, and these methods cannot be applied in practice when morphological information is limited. Molecular methods for age estimation have been extensively developed in the last few years. The fact that telomeres shorten at each round of cell division has led to the hypothesis that telomere length can be used as a tool to predict age. The present study thus aimed to assess the correlation between telomere length measured in dental DNA and age, and the effect of sex and tooth type on telomere length; a further aim was to propose a statistical regression model to estimate the biological age based on telomere length. DNA was extracted from 91 tooth samples belonging to 77 individuals of both sexes and 15 to 85 years old and was used to determine telomere length by quantitative real-time PCR. Our results suggested that telomere length was not affected by sex and was greater in molar teeth. We found a significant correlation between age and telomere length measured in DNA from teeth. However, the equation proposed to predict age was not accurate enough for forensic age estimation on its own. Age estimation based on telomere length in DNA from tooth samples may be useful as a complementary method which provides an approximate estimate of age, especially when human skeletal remains are the only forensic sample available.

Axial nonuniformity of geometric and mechanical properties of mouse aorta is increased during postnatal growth.

PubMed

Huang, Yi; Guo, Xiaomei; Kassab, Ghassan S

2006-02-01

The hemodynamic conditions of aorta are relatively uniform prenatally and become more heterogeneous postnatally. Our objective was to quantify the heterogeneity of geometry and mechanical properties during growth and development. To accomplish this objective, we obtained a systematic set of data on the geometry and mechanical properties along the length of mouse aorta during postnatal development. C57BL/6 mice of ages 1-33 days were studied. The ascending aorta was cannulated in situ and preconditioned with several cyclic changes in pressure. We investigated the axial variations of geometry (diameter and length) and mechanical properties (stress-stain relation, elastic modulus and compliance) of the mouse aorta from the aortic valve to the common iliac. Our results show that the arterial blood pressure of mice increased from approximately 30 to 80 mmHg during the first 2 wk of life. The stretch ratio, diameter, wall (intima-media) thickness, and total lumen volume of mouse aorta increased with age. The aorta was transformed from a cylindrical tube at birth to a tapered structure during growth. Furthermore, we found the mechanical properties were fairly uniform along the length of the aorta at birth and become more nonuniform with age. We conclude that the rapid change of blood pressure and blood flow after birth alter the geometric and mechanical properties differentially along the length of the aorta. Hence, the axial nonuniformity of the aorta increases as the organ becomes more specialized during growth and development.

Relationship between changes in crystalline lens shape and axial elongation in young children.

PubMed

Ishii, Kotaro; Yamanari, Masahiro; Iwata, Hiroyoshi; Yasuno, Yoshiaki; Oshika, Tetsuro

2013-01-28

To evaluate the relationship between changes in crystalline lens shape and axial elongation during growth in young children. Twenty-five patients (age: 1 month to 6 years) who underwent head magnetic resonance imaging (MRI) were included in the analysis. Refractive error was measured with an autorefractor in 22 patients. Crystalline lens dimensions and axial length (AL) were obtained from the MR images. The radius of curvature and asphericity of the crystalline lens were measured using reconstructed MR images. Crystalline lens shape and eyeball shape were numerically expressed by elliptic Fourier descriptors (EFDs) on the basis of MR images. The contours of the crystalline lens and eyeball were evaluated by principal component analysis of the EFDs. The average anterior and posterior radii of curvature were 6.21 mm (range across ages from 3.89-7.26 mm) and -4.81 mm (range across ages from -2.93 to -5.67 mm). These were closely correlated with age by logarithmic analysis. The first principal component (PC1) of the crystalline lens explained 89.15% of the total variance in lens shape, and it was also significantly correlated with age (Pearson's r = 0.648, P < 0.001) and AL (r = 0.847, P < 0.001). In the multiple linear regression analysis in which AL was a dependent variable, only the PC1 of the crystalline lens was associated with AL. Axial elongation is related to the entire contour of the crystalline lens. This result shows that axial elongation progresses in parallel to change in the crystalline lens shape.

A comparison of age-related changes in axial prestretch in human carotid arteries and in human abdominal aorta.

PubMed

Horný, Lukáš; Adámek, Tomáš; Kulvajtová, Markéta

2017-02-01

It is known that large arteries in situ are subjected to significant axial prestretch. This prestretch plays an important physiological role in optimizing the biomechanical response of an artery. It is also known that the prestretch declines with age. However, a detailed description of age-related changes in prestretch is available only for the abdominal aorta and for the femoropliteal artery. Our study presents results of measurements of axial prestretch in 229 left common carotid arteries excised in autopsies. It was found that the prestretch of the carotid artery correlates significantly with age ([Formula: see text], p value < 0.001). A linear regression model was used to fit the observations. Simultaneously with the measurement of the prestretch in the carotid artery, the axial prestretch was also measured in abdominal aorta. By comparing data obtained from these locations, it was concluded that the axial prestretch in the carotid artery is greater than in the abdominal aorta, and that atherosclerosis develops more rapidly in the abdominal aorta than in the carotid artery. Histological sections obtained from 8 carotid arteries and aortas suggest that the medial layer of the left common carotid artery is significantly thinner than aortic media (median/IQR: 0.343/0.086 vs. 0.482/0.172 mm, [Formula: see text] in Wilcoxon signed-rank test) and simultaneously that carotid media contains a lower number of elastic membranes (median/IQR: 26.5/11.8 vs. 31.5/11.8, [Formula: see text] in the Wilcoxon signed-rank test). This could be a reason for the different extent of the prestretch observed in aorta and in carotid artery. Our data sample also contains 5 measurements of the axial prestretch in abdominal aortas suffering from an aneurysm. It was found that aneurysmatic aortas also exhibit axial retraction when excised from in situ position. To the best of our knowledge, this is the first time that detailed data characterizing axial prestretch of the human left common

Axial superchargers

NASA Technical Reports Server (NTRS)

Betz, A

1944-01-01

Improvements, however, have been attained which permit a shortening of the structure without any impairment of the efficiency. The axial supercharger has a better efficiency and a simpler design than the radial supercharger. The relatively narrow range in which it operates satisfactorily should not be a very disturbing factor for practical flight problems. The length of this type of supercharger may be reduced considerably if some impairment in the efficiency is permitted.

Leukocyte telomere length and marital status among middle-aged adults

PubMed Central

Mainous, Arch G.; Everett, Charles J.; Diaz, Vanessa A.; Baker, Richard; Mangino, Massimo; Codd, Veryan; Samani, Nilesh J.

2011-01-01

Background: being unmarried is associated with worse health and increased mortality risk. Telomere length has emerged as a marker for biological ageing but it is unclear how telomere length relates to marital status. Objective: to examine the relationship between telomere length and marital status in a sample of middle-aged adults. Design and subjects: cross-sectional analysis among 321 adults aged 40–64 years. Methods: telomere length was measured by PCR (T/S ratio). Participants provided information on healthy lifestyle activities including smoking, alcohol use, diet, exercise, obesity as well as social support. Results: participants married or living with a partner had a mean T/S ratio of 1.70 and those widowed, divorced, separated or never married had a mean T/S ratio of 1.58 in a model adjusted for age, gender and race/ethnicity (P < 0.001). When the analysis was further adjusted for diet, alcohol consumption, exercise, smoking, social support, poverty and obesity, persons married or living with a partner had a higher mean T/S ratio of 1.69 than their unmarried counterparts (1.59) (P = 0.004). Conclusions: these results indicate that unmarried individuals have shorter telomeres. This relationship between marital status and telomere length is independent of presumed benefits of marriage such as social support and a healthier lifestyle. PMID:20817935

Maximum step length: relationships to age and knee and hip extensor capacities.

PubMed

Schulz, Brian W; Ashton-Miller, James A; Alexander, Neil B

2007-07-01

Maximum Step Length may be used to identify older adults at increased risk for falls. Since leg muscle weakness is a risk factor for falls, we tested the hypotheses that maximum knee and hip extension speed, strength, and power capacities would significantly correlate with Maximum Step Length and also that the "step out and back" Maximum Step Length [Medell, J.L., Alexander, N.B., 2000. A clinical measure of maximal and rapid stepping in older women. J. Gerontol. A Biol. Sci. Med. Sci. 55, M429-M433.] would also correlate with the Maximum Step Length of its two sub-tasks: stepping "out only" and stepping "back only". These sub-tasks will be referred to as versions of Maximum Step Length. Unimpaired younger (N=11, age=24[3]years) and older (N=10, age=73[5]years) women performed the above three versions of Maximum Step Length. Knee and hip extension speed, strength, and power capacities were determined on a separate day and regressed on Maximum Step Length and age group. Version and practice effects were quantified and subjective impressions of test difficulty recorded. Hypotheses were tested using linear regressions, analysis of variance, and Fisher's exact test. Maximum Step Length explained 6-22% additional variance in knee and hip extension speed, strength, and power capacities after controlling for age group. Within- and between-block and test-retest correlation values were high (>0.9) for all test versions. Shorter Maximum Step Lengths are associated with reduced knee and hip extension speed, strength, and power capacities after controlling for age. A single out-and-back step of maximal length is a feasible, rapid screening measure that may provide insight into underlying functional impairment, regardless of age.

Electrochemical cell apparatus having axially distributed entry of a fuel-spent fuel mixture transverse to the cell lengths

DOEpatents

Reichner, P.; Dollard, W.J.

1991-01-08

An electrochemical apparatus is made having a generator section containing axially elongated electrochemical cells, a fresh gaseous feed fuel inlet, a gaseous feed oxidant inlet, and at least one gaseous spent fuel exit channel, where the spent fuel exit channel passes from the generator chamber to combine with the fresh feed fuel inlet at a mixing apparatus, reformable fuel mixture channel passes through the length of the generator chamber and connects with the mixing apparatus, that channel containing entry ports within the generator chamber, where the axis of the ports is transverse to the fuel electrode surfaces, where a catalytic reforming material is distributed near the reformable fuel mixture entry ports. 2 figures.

Comparing the Relationship Between Age and Length of Disability Across Common Chronic Conditions

PubMed Central

Jetha, Arif; Besen, Elyssa; Smith, Peter M.

2016-01-01

Objective: The aim of this study was to compare the association between age and disability length across common chronic conditions. Methods: Analysis of 39,915 nonwork-related disability claims with a diagnosis of arthritis, diabetes, hypertension, coronary artery disease, depression, low back pain, chronic pulmonary disease, or cancer. Ordinary least squares regression models examined age-length of disability association across chronic conditions. Results: Arthritis (76.6 days), depression (63.2 days), and cancer (64.9 days) were associated with longest mean disability lengths; hypertension was related to shortest disability lengths (41.5 days). Across chronic conditions, older age was significantly associated with longer work disability. The age–length of disability association was most significant for chronic pulmonary disease and cancer. The relationship between age and length of work disability was linear among most chronic conditions. Conclusions: Work disability prevention strategies should consider both employee age and chronic condition diagnosis. PMID:27164446

Method to Measure Tone of Axial and Proximal Muscle

PubMed Central

Gurfinkel, Victor S.; Cacciatore, Timothy W.; Cordo, Paul J.; Horak, Fay B.

2011-01-01

The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention. PMID:22214974

Telomere Length in Epidemiology: A Biomarker of Aging, Age-Related Disease, Both, or Neither?

PubMed Central

Sanders, Jason L.; Newman, Anne B.

2013-01-01

Telomeres are nucleoprotein caps flanking DNA. They are shortened by cell division and oxidative stress and are lengthened by the enzyme telomerase and DNA exchange during mitosis. Short telomeres induce cellular senescence. As an indicator of oxidative stress and senescence (2 processes thought to be fundamental to aging), telomere length is hypothesized to be a biomarker of aging. This hypothesis has been tested for more than a decade with epidemiologic study methods. In cross-sectional studies, researchers have investigated whether leukocyte telomere length (LTL) is associated with demographic, behavioral, and health variables. In prospective studies, baseline LTL has been used to predict mortality and occasionally other adverse health outcomes. Conflicting data have generated heated debate about the value of LTL as a biomarker of overall aging. In this review, we address the epidemiologic data on LTL and demonstrate that shorter LTL is associated with older age, male gender, Caucasian race, and possibly atherosclerosis; associations with other markers of health are equivocal. We discuss the reasons for discrepancy across studies, including a detailed review of methods for measuring telomere length as they apply to epidemiology. Finally, we conclude with questions about LTL as a biomarker of aging and how epidemiology can be used to answer these questions. PMID:23302541

Analysis of the age of Panax ginseng based on telomere length and telomerase activity.

PubMed

Liang, Jiabei; Jiang, Chao; Peng, Huasheng; Shi, Qinghua; Guo, Xiang; Yuan, Yuan; Huang, Luqi

2015-01-23

Ginseng, which is the root of Panax ginseng (Araliaceae), has been used in Oriental medicine as a stimulant and dietary supplement for more than 7,000 years. Older ginseng plants are substantially more medically potent, but ginseng age can be simulated using unscrupulous cultivation practices. Telomeres progressively shorten with each cell division until they reach a critical length, at which point cells enter replicative senescence. However, in some cells, telomerase maintains telomere length. In this study, to determine whether telomere length reflects ginseng age and which tissue is best for such an analysis, we examined telomerase activity in the main roots, leaves, stems, secondary roots and seeds of ginseng plants of known age. Telomere length in the main root (approximately 1 cm below the rhizome) was found to be the best indicator of age. Telomeric terminal restriction fragment (TRF) lengths, which are indicators of telomere length, were determined for the main roots of plants of different ages through Southern hybridization analysis. Telomere length was shown to be positively correlated with plant age, and a simple mathematical model was formulated to describe the relationship between telomere length and age for P. ginseng.

Macular Pigment Optical Density and Ocular Pulse Amplitude in Subjects with Different Axial Lengths and Refractive Errors.

PubMed

Czepita, Maciej; Karczewicz, Danuta; Safranow, Krzysztof; Czepita, Damian

2015-06-13

The purpose of our study was to: (1) investigate the macular pigment optical density (MPOD) and ocular pulse amplitude (OPA) in subjects with different axial lengths (AL) and refractive errors (RE); (2) determine if there is a correlation between MPOD and OPA; and (3) evaluate whether MPOD and OPA depend on intraocular pressure (IOP). This study included 140 eyes of 70 subjects - 17 men and 53 women, aged 18 to 29 years (mean: 22.5 years; SD=2.8). Every examined person underwent a thorough eye examination including: visual acuity, anterior segment and fundus examination, keratometry, auto-refractometry, and MPOD, OPA, AL, and IOP measurements. The obtained results were analyzed statistically using Statistica 10 software. P values of <0.05 were considered statistically significant. The following refractive errors were selected: emmetropia (34 eyes), hyperopia (18 eyes), low myopia (60 eyes), medium myopia (19 eyes), and high myopia (9 eyes). It has been established that the OPA increases with the rise in the spherical equivalents (SE) (Rs=+0.38, P<0.001), while the increase in AL correlates with the decrease of OPA (Rs=-0.40, P<0.001). The increase in IOP correlates with the rise in the OPA (Rs=+0.20, P<0.05). There were no significant correlations between IOP and SE or AL. (1) MPOD is not correlated with the OPA in subjects with different AL and RE; (2) OPA decreases with the rise of AL; (3) OPA decreases with the fall of the SE; and (4) OPA increases with the rise in IOP.

Does Relative Age Affect Career Length in North American Professional Sports?

PubMed

Steingröver, C; Wattie, N; Baker, J; Schorer, J

Relative age effects (RAEs) typically favour older members within a cohort; however, research suggests that younger players may experience some long-term advantages, such as longer career length. The purposes of this study were to replicate previous findings on RAEs among National Hockey League (NHL) ice hockey players, National Basketball Association (NBA) basketball players and National Football League (NFL) football players and to investigate the influence of relative age on career length in all three sports. Using official archives, birthdates and number of games played were collected for players drafted into the NBA ( N  = 407), NFL ( N  = 2380) and NHL ( N  = 1028) from 1980 to 1989. We investigated the possibility that younger players might be able to maximize their career length by operationalizing career length as players' number of games played throughout their careers. There was a clear RAE for the NHL, but effects were not significant for the NBA or NFL. Moreover, there was a significant difference in matches played between birth quartiles in the NHL favouring relatively younger players. There were no significant quartiles by career length effects in the NBA or NFL. The significant relationship between relative age and career length provides further support for relative age as an important constraint on expertise development in ice hockey but not basketball or football. Currently, the reason why relatively younger players have longer careers is not known. However, it may be worth exploring the influence of injury risk or the development of better playing skills.

Physical activity and telomere length: Impact of aging and potential mechanisms of action.

PubMed

Arsenis, Nicole C; You, Tongjian; Ogawa, Elisa F; Tinsley, Grant M; Zuo, Li

2017-07-04

Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations.

Decreasing initial telomere length in humans intergenerationally understates age-associated telomere shortening

PubMed Central

Holohan, Brody; De Meyer, Tim; Batten, Kimberly; Mangino, Massimo; Hunt, Steven C; Bekaert, Sofie; De Buyzere, Marc L; Rietzschel, Ernst R; Spector, Tim D; Wright, Woodring E; Shay, Jerry W

2015-01-01

Telomere length shortens with aging, and short telomeres have been linked to a wide variety of pathologies. Previous studies suggested a discrepancy in age-associated telomere shortening rate estimated by cross-sectional studies versus the rate measured in longitudinal studies, indicating a potential bias in cross-sectional estimates. Intergenerational changes in initial telomere length, such as that predicted by the previously described effect of a father’s age at birth of his offspring (FAB), could explain the discrepancy in shortening rate measurements. We evaluated whether changes occur in initial telomere length over multiple generations in three large datasets and identified paternal birth year (PBY) as a variable that reconciles the difference between longitudinal and cross-sectional measurements. We also clarify the association between FAB and offspring telomere length, demonstrating that this effect is substantially larger than reported in the past. These results indicate the presence of a downward secular trend in telomere length at birth over generational time with potential public health implications. PMID:25952108

Electrochemical cell apparatus having axially distributed entry of a fuel-spent fuel mixture transverse to the cell lengths

DOEpatents

Reichner, Philip; Dollard, Walter J.

1991-01-01

An electrochemical apparatus (10) is made having a generator section (22) containing axially elongated electrochemical cells (16), a fresh gaseous feed fuel inlet (28), a gaseous feed oxidant inlet (30), and at least one gaseous spent fuel exit channel (46), where the spent fuel exit channel (46) passes from the generator chamber (22) to combine with the fresh feed fuel inlet (28) at a mixing apparatus (50), reformable fuel mixture channel (52) passes through the length of the generator chamber (22) and connects with the mixing apparatus (50), that channel containing entry ports (54) within the generator chamber (22), where the axis of the ports is transverse to the fuel electrode surfaces (18), where a catalytic reforming material is distributed near the reformable fuel mixture entry ports (54).

Physical activity and telomere length: Impact of aging and potential mechanisms of action

PubMed Central

Arsenis, Nicole C.; You, Tongjian; Ogawa, Elisa F.; Tinsley, Grant M.; Zuo, Li

2017-01-01

Telomeres protect the integrity of information-carrying DNA by serving as caps on the terminal portions of chromosomes. Telomere length decreases with aging, and this contributes to cell senescence. Recent evidence supports that telomere length of leukocytes and skeletal muscle cells may be positively associated with healthy living and inversely correlated with the risk of several age-related diseases, including cancer, cardiovascular disease, obesity, diabetes, chronic pain, and stress. In observational studies, higher levels of physical activity or exercise are related to longer telomere lengths in various populations, and athletes tend to have longer telomere lengths than non-athletes. This relationship is particularly evident in older individuals, suggesting a role of physical activity in combating the typical age-induced decrements in telomere length. To date, a small number of exercise interventions have been executed to examine the potential influence of chronic exercise on telomere length, but these studies have not fully established such relationship. Several potential mechanisms through which physical activity or exercise could affect telomere length are discussed, including changes in telomerase activity, oxidative stress, inflammation, and decreased skeletal muscle satellite cell content. Future research is needed to mechanistically examine the effects of various modalities of exercise on telomere length in middle-aged and older adults, as well as in specific clinical populations. PMID:28410238

Is there a correlation between right bronchus length and diameter with age?

PubMed

Otoch, José Pinhata; Minamoto, Hélio; Perini, Marcos; Carneiro, Fred Olavo; de Almeida Artifon, Everson Luiz

2013-06-01

Right main bronchial anatomy knowledge is essential to guide endoscopic stent placement in modern era. The aim is to describe right bronchial anatomy, cross-area and its relation with the right pulmonary artery and patient's age. One hundred thirty four cadaveric specimens were studied after approval by the Research and Ethics Committee at the University of São Paulo Medical School and Medical Forensic Institute of São Paulo. All necropsies were performed in natura after 24 hours of death and patients with previous pulmonary disease were excluded. Landmarks to start measurement were the first tracheal ring, vertex of carina, first right bronchial ring, and right pulmonary artery area over the right main bronchus. After mobilization, the specimens were measured using a caliper and measurement of distances was recorded in centimeters at landmarks points. All the measures (distances, cross sectional area and planes) were performed by three independent observers and recorded as mean, standard error and ranges. Student t test was used to compare means and linear regression was applied to correlate the measurements. From 134 specimens studied, 34 were excluded (10 with previous history of pulmonary diseases, surgery or deformities and 24 of female gender). Linear regression showed proportionality between tracheal length and right bronchus length; with the area at first tracheal ring and carina and also between the cross sectional area at these points. Linear regression analysis between tracheal length and age (R=0.593 P<0.005), right bronchus length and age (R=0.523, P<0.005), area of contact between right bronchus and right pulmonary artery and age (R=0.35, P<0.005). We can conclude that large airways grow progressively with increasing age in male gender. There was a direct correlation between age and tracheal length; as has age and right bronchus length. There was a direct correlation between age and the area of the right bronchus covered by the right pulmonary

Fetal kidney length as a useful adjunct parameter for better determination of gestational age.

PubMed

Ugur, Mete G; Mustafa, Aynur; Ozcan, Huseyin C; Tepe, Neslihan B; Kurt, Huseyin; Akcil, Emre; Gunduz, Reyhan

2016-05-01

To determine the validity of fetal kidney length and amniotic fluid index (AFI) in labor dating.  This prospective study included 180 pregnant women followed up in the outpatient clinic at the Department of Obstetrics and Gynecology, Gaziantep University, Turkey, between January 2014 and January 2015. The gestational age (GA) was estimated by early fetal ultrasound measures and last menstrual period. Routine fetal biometric parameters, fetal kidney length, and amniotic fluid index were measured. We studied the correlation between fetal kidney length, amniotic fluid index, and gestational age.  The mean gestational age depending on last menstrual period and early ultrasound was 31.98±4.29 (24-39 weeks). The mean kidney length was 35.66±6.61 (19-49 mm). There was a significant correlation between gestational age and fetal kidney length (r=0.947, p=0.001). However, there was a moderate negative correlation between GA and AFI. Adding fetal kidney length to the routine biometrics improved the effectiveness of the model used to estimate GA (R2=0.965 to R2=0.987).  Gestational age can be better predicted by adding fetal kidney length to other routine parameters.

Hierarchical Bayesian analysis to incorporate age uncertainty in growth curve analysis and estimates of age from length: Florida manatee (Trichechus manatus) carcasses

USGS Publications Warehouse

Schwarz, L.K.; Runge, M.C.

2009-01-01

Age estimation of individuals is often an integral part of species management research, and a number of ageestimation techniques are commonly employed. Often, the error in these techniques is not quantified or accounted for in other analyses, particularly in growth curve models used to describe physiological responses to environment and human impacts. Also, noninvasive, quick, and inexpensive methods to estimate age are needed. This research aims to provide two Bayesian methods to (i) incorporate age uncertainty into an age-length Schnute growth model and (ii) produce a method from the growth model to estimate age from length. The methods are then employed for Florida manatee (Trichechus manatus) carcasses. After quantifying the uncertainty in the aging technique (counts of ear bone growth layers), we fit age-length data to the Schnute growth model separately by sex and season. Independent prior information about population age structure and the results of the Schnute model are then combined to estimate age from length. Results describing the age-length relationship agree with our understanding of manatee biology. The new methods allow us to estimate age, with quantified uncertainty, for 98% of collected carcasses: 36% from ear bones, 62% from length.

A tubular hybrid Halbach/axially-magnetized permanent-magnet linear machine

NASA Astrophysics Data System (ADS)

Sui, Yi; Liu, Yong; Cheng, Luming; Liu, Jiaqi; Zheng, Ping

2017-05-01

A single-phase tubular permanent-magnet linear machine (PMLM) with hybrid Halbach/axially-magnetized PM arrays is proposed for free-piston Stirling power generation system. Machine topology and operating principle are elaborately illustrated. With the sinusoidal speed characteristic of the free-piston Stirling engine considered, the proposed machine is designed and calculated by finite-element analysis (FEA). The main structural parameters, such as outer radius of the mover, radial length of both the axially-magnetized PMs and ferromagnetic poles, axial length of both the middle and end radially-magnetized PMs, etc., are optimized to improve both the force capability and power density. Compared with the conventional PMLMs, the proposed machine features high mass and volume power density, and has the advantages of simple control and low converter cost. The proposed machine topology is applicable to tubular PMLMs with any phases.

Low serum vitamin D is associated with axial length and risk of myopia in young children.

PubMed

Tideman, J Willem L; Polling, Jan Roelof; Voortman, Trudy; Jaddoe, Vincent W V; Uitterlinden, André G; Hofman, Albert; Vingerling, Johannes R; Franco, Oscar H; Klaver, Caroline C W

2016-05-01

The aim of the study was to investigate the relationship between serum 25(OH)D levels and axial length (AL) and myopia in 6-year-old children. A total of 2666 children aged 6 years participating in the birth-cohort study Generation R underwent a stepwise eye examination. First, presenting visual acuity (VA) and AL were performed. Second, automated cycloplegic refraction was measured if LogMAR VA > 0.1. Serum 25-hydroxyvitamin D [25(OH)D] was determined from blood using liquid chromatography/tandem mass spectrometry. Vitamin D related SNPs were determined with a SNP array; outdoor exposure was assessed by questionnaire. The relationships between 25(OH)D and AL or myopia were investigated using linear and logistic regression analysis. Average 25(OH)D concentration was 68.8 nmol/L (SD ± 27.5; range 4-211); average AL 22.35 mm (SD ± 0.7; range 19.2-25.3); and prevalence of myopia 2.3 % (n = 62). After adjustment for covariates, 25(OH)D concentration (per 25 nmol/L) was inversely associated with AL (β -0.043; P < 0.01), and after additional adjusting for time spent outdoors (β -0.038; P < 0.01). Associations were not different between European and non-European children (β -0.037 and β -0.039 respectively). Risk of myopia (per 25 nmol/L) was OR 0.65 (95 % CI 0.46-0.92). None of the 25(OH)D related SNPs showed an association with AL or myopia. Lower 25(OH)D concentration in serum was associated with longer AL and a higher risk of myopia in these young children. This effect appeared independent of outdoor exposure and may suggest a more direct role for 25(OH)D in myopia pathogenesis.

Axially staggered seed-blanket reactor fuel module construction

DOEpatents

Cowell, Gary K.; DiGuiseppe, Carl P.

1985-01-01

A heterogeneous nuclear reactor of the seed-blanket type is provided wher the fissile (seed) and fertile (blanket) nuclear fuels are segregated axially within each fuel element such that fissile and fertile regions occur in an alternating pattern along the length of the fuel element. Further, different axial stacking patterns are used for the fuel elements of at least two module types such that when modules of different types are positioned adjacent to one another, the fertile regions of the modules are offset or staggered. Thus, when a module of one type is surrounded by modules of the second type the fertile regions thereof will be surrounded on all sides by fissile material. This provides enhanced neutron communication both radially and axially, thereby resulting in greater power oscillation stability than other axial arrangements. The arrangements of the fissile and fertile regions in an alternating axial manner minimizes the radial power peaking factors and provides a more optional thermal-hydraulic design than is afforded by radial arrangements.

Paternal age and telomere length in twins: the germ stem cell selection paradigm

PubMed Central

Hjelmborg, Jacob B; Dalgård, Christine; Mangino, Massimo; Spector, Tim D; Halekoh, Ulrich; Möller, Sören; Kimura, Masayuki; Horvath, Kent; Kark, Jeremy D; Christensen, Kaare; Kyvik, Kirsten O; Aviv, Abraham

2015-01-01

Telomere length, a highly heritable trait, is longer in offspring of older fathers. This perplexing feature has been attributed to the longer telomeres in sperm of older men and it might be an ‘epigenetic’ mechanism through which paternal age plays a role in telomere length regulation in humans. Based on two independent (discovery and replication) twin studies, comprising 889 twin pairs, we show an increase in the resemblance of leukocyte telomere length between dizygotic twins of older fathers, which is not seen in monozygotic twins. This phenomenon might result from a paternal age-dependent germ stem cell selection process, whereby the selected stem cells have longer telomeres, are more homogenous with respect to telomere length, and share resistance to aging. PMID:25865872

Estimation of gestational age from hand and foot length.

PubMed

Kumar, G P; Kumar, U K

1994-01-01

Abortion, foeticide and infanticide have been practised from time immemorial by both primitive and civilized societies. Establishing the precise duration of gestation is an important point in the total medical evidentiary picture of infanticide. In this study, an attempt has been made to establish the gestational age of the foetus using foot and hand length. This study will be of help in establishing the gestational age when the foetus is fragmented. Results obtained were significant in establishing the gestational age.

Association of lifestyle and body structure to ocular axial length in Japanese elementary school children.

PubMed

Terasaki, Hiroto; Yamashita, Takehiro; Yoshihara, Naoya; Kii, Yuya; Sakamoto, Taiji

2017-07-12

The purpose of this study is to determine whether the lifestyle and body stature are significantly associated with the axial length (AL) of the eyes of Japanese third grade students. A prospective, cross sectional, observational study was performed on 122 third grade students consisting of 61 boys and 61 girls ages 8 to 9 years. The AL, body height, body weight, and body mass index (BMI) were measured. The lifestyle was determined by activities such as the daily duration of indoor studying, television viewing, use of computers and smart phones, outdoor activity time, bed time, Japanese or Western dietary habits, and parental myopia were investigated by a questionnaire with three or five grade levels. The relationship between AL and the questionnaire variables were analyzed by Spearman's correlation analyses. Westernized dietary habits (r = -0.24, P = 0.01), duration of computer and smart phone use (r = 0.24, P = 0.008), parental myopia (r = 0.39, P < 0.001), body weight (r = 0.26, P = 0.005), and BMI (r = 0.23, P = 0.011) were significantly correlated with the AL. Multiple logistic regression analyses showed that the sex [r = -0.48; 95% confidence interval (CI) -0.80 to -0.17, P = 0.003], body weight (r = 0.04; 95% CI 0.02 to 0.07, P = 0.038), westernized dietary habits (r = -0.30; 95% CI -0.55 to -0.05, P = 0.021), and parental myopia (r = 0.40; 95% CI 0.20 to 0.61, P < 0.001) were significantly and independently correlated with the AL. The body weight and parental myopia and westernized dietary habits are factors significantly associated with myopia. Changing from Japanese food style to westernized food style might increase the risk of progression of school myopia.

Diurnal variations in axial length, choroidal thickness, intraocular pressure, and ocular biometrics.

PubMed

Chakraborty, Ranjay; Read, Scott A; Collins, Michael J

2011-07-11

To investigate the pattern of diurnal variations in axial length (AL), choroidal thickness, intraocular pressure (IOP), and ocular biometrics over 2 consecutive days. Measurements of ocular biometrics and IOP were collected for 30 young adult subjects (15 myopes, 15 emmetropes) at 10 different times over 2 consecutive days. Five sets of measurements were collected each day at approximately 3-hour intervals, with the first measurement taken at ~9 AM and final measurement at ~9 PM. AL underwent significant diurnal variation (P < 0.0001) that was consistently observed across the 2 measurement days. The longest AL was typically observed at the second measurement session (mean time, 12:26) and the shortest AL at the final session of each day (mean time, 21:06). The mean diurnal change in AL was 0.032 ± 0.018 mm. Choroidal thickness underwent significant diurnal variation (mean change, 0.029 ± 0.016 mm; P < 0.001) and varied approximately in antiphase to the AL changes. Significant diurnal variations were also found in vitreous chamber depth (VCD; mean change, 0.06 ± 0.029 mm; P < 0.0001) and IOP (mean change, 3.54 ± 0.84 mm Hg; P < 0.0001). A positive association was found between the variations of AL and IOP (r(2) = 0.17, P < 0.0001) and AL and VCD (r(2) = 0.31, P < 0.0001) and a negative association between AL and choroidal thickness (r(2) = 0.13, P < 0.0001). There were no significant differences in the magnitude and timing of diurnal variations associated with refractive error. Significant diurnal variations in AL, choroidal thickness, and IOP were consistently observed over 2 consecutive days of testing.

Influence of tip end-plate on noise of small axial fan

NASA Astrophysics Data System (ADS)

Mao, Hongya; Wang, Yanping; Lin, Peifeng; Jin, Yingzi; Setoguchi, Toshiaki; Kim, Heuy Dong

2017-02-01

In this work, tip end-plate is used to improve the noise performance of small axial fans. Both numerical simulations and experimental methods were adopted to study the fluid flow and noise level of axial fans. Four modified models and the prototype are simulated. Influences of tip end-plate on static characteristics, internal flow field and noise of small axial fans are analyzed. The results show that on basis of the prototype, the model with the tip end-plate of 2 mm width and changed length achieved best noise performance. The overall sound pressure level of the model with the tip end-plate of 2 mm width and changed length is 2.4 dB less than that of the prototype at the monitoring point in specified far field. It is found that the mechanism of noise reduction is due to the decrease of vorticity variation on the surface of blades caused by the tip end-plate. Compared with the prototype, the static pressure of the model with the tip end-plate of 2 mm width and changed length at design flow rate decreases by 2 Pa and the efficiency decreases by 0.8%. It is concluded that the method of adding tip end-plate to impeller blades has a positive influence on reducing noise, but it may diminish the static characteristics of small axial fan to some extent.

Long axial imaging range using conventional swept source lasers in optical coherence tomography via re-circulation loops

NASA Astrophysics Data System (ADS)

Bradu, Adrian; Jackson, David A.; Podoleanu, Adrian

2018-03-01

Typically, swept source optical coherence tomography (SS-OCT) imaging instruments are capable of a longer axial range than their camera based (CB) counterpart. However, there are still various applications that would take advantage for an extended axial range. In this paper, we propose an interferometer configuration that can be used to extend the axial range of the OCT instruments equipped with conventional swept-source lasers up to a few cm. In this configuration, the two arms of the interferometer are equipped with adjustable optical path length rings. The use of semiconductor optical amplifiers in the two rings allows for compensating optical losses hence, multiple paths depth reflectivity profiles (Ascans) can be combined axially. In this way, extremely long overall axial ranges are possible. The use of the recirculation loops produces an effect equivalent to that of extending the coherence length of the swept source laser. Using this approach, the achievable axial imaging range in SS-OCT can reach values well beyond the limit imposed by the coherence length of the laser, to exceed in principle many centimeters. In the present work, we demonstrate axial ranges exceeding 4 cm using a commercial swept source laser and reaching 6 cm using an "in-house" swept source laser. When used in a conventional set-up alone, both these lasers can provide less than a few mm axial range.

Axially staggered seed-blanket reactor-fuel-module construction. [LWBR

DOEpatents

Cowell, G.K.; DiGuiseppe, C.P.

1982-10-28

A heterogeneous nuclear reactor of the seed-blanket type is provided wherein the fissile (seed) and fertile (blanket) nuclear fuels are segregated axially within each fuel element such that fissile and fertile regions occur in an alternating pattern along the length of the fuel element. Further, different axial stacking patterns are used for the fuel elements of at least two module types such that when modules of different types are positioned adjacent to one another, the fertile regions of the modules are offset or staggered. Thus, when a module of one type is surrounded by modules of the second type the fertile regions thereof will be surrounded on all sides by fissile material. This provides enhanced neutron communication both radially and axially, thereby resulting in greater power oscillation stability than other axial arrangements.

Axially staged combustion system for a gas turbine engine

DOEpatents

Bland, Robert J [Oviedo, FL

2009-12-15

An axially staged combustion system is provided for a gas turbine engine comprising a main body structure having a plurality of first and second injectors. First structure provides fuel to at least one of the first injectors. The fuel provided to the one first injector is adapted to mix with air and ignite to produce a flame such that the flame associated with the one first injector defines a flame front having an average length when measured from a reference surface of the main body structure. Each of the second injectors comprising a section extending from the reference surface of the main body structure through the flame front and having a length greater than the average length of the flame front. Second structure provides fuel to at least one of the second injectors. The fuel passes through the one second injector and exits the one second injector at a location axially spaced from the flame front.

Novel Integration Radial and Axial Magnetic Bearing

NASA Technical Reports Server (NTRS)

Blumenstock, Kenneth; Brown, Gary

2000-01-01

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

Novel Integrated Radial and Axial Magnetic Bearing

NASA Technical Reports Server (NTRS)

Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

2000-01-01

Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

Axial force measurement for esophageal function testing

PubMed Central

Gravesen, Flemming H; Funch-Jensen, Peter; Gregersen, Hans; Drewes, Asbjørn Mohr

2009-01-01

The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method. PMID:19132762

CHOROIDAL THICKNESS IN HEALTHY CHINESE CHILDREN AGED 6 to 12: The Shanghai Children Eye Study.

PubMed

He, Xiangui; Jin, Peiyao; Zou, Haidong; Li, Qiangqiang; Jin, Jiali; Lu, Lina; Zhao, Huijuan; He, Jiangnan; Xu, Xun; Wang, Mingjin; Zhu, Jianfeng

2017-02-01

To explore the characteristics of choroidal thickness (ChT) in Chinese children. A total of 144 healthy children, aged 6 years to 12 years old, were enrolled in the study. The ChT of subfovea and peripheral locations 0.5, 1.5, and 2.5 mm away from the fovea were evaluated by enhanced depth imaging optical coherence tomography. The association between subfoveal ChT and systemic, as well as ocular factors, including age, sex, height, weight, body mass index, axial length, refractive error, intraocular pressure, preterm history, and the refractive status of parents were studied. The mean subfoveal ChT was 302 ± 63 μm. In the nasal, superior, and inferior areas, the ChT of locations closer to the fovea was thicker than those farther away from the fovea (all P < 0.05); however, ChT was not significantly different among different locations in the temporal area (P = 0.16). The ChT of the nasal quadrant was significantly thinner than that of other areas (P < 0.01). Subfoveal ChT decreased with age, axial length, preterm history, and increased with height. Sex was not statistically associated with subfoveal ChT. In Chinese children, the ChT is thinnest in the nasal quadrant and thicker in central regions than in peripheral areas. The subfoveal ChT independently decreases with age, axial length, preterm history, and increases with height.

Romantic Relationship Development: The Interplay between Age and Relationship Length

ERIC Educational Resources Information Center

Lantagne, Ann; Furman, Wyndol

2017-01-01

The present study explored how romantic relationship qualities develop with age and relationship length. Eight waves of data on romantic relationships were collected over 10.5 years during adolescence and early adulthood from a community-based sample in a Western U.S. city (100 males, 100 females; M age Wave 1 = 15.83). Measures of support,…

Correction of axial deformity during lengthening in fibular hypoplasia: Hexapodal versus monorail external fixation.

PubMed

Chalopin, A; Geffroy, L; Pesenti, S; Hamel, A; Launay, F

2017-09-01

Childhood fibular hypoplasia is a rare pathology which may or may not involve limb-length discrepancy and axial deformity in one or more dimensions. The objective of the present study was to compare the quality of the axial correction achieved in lengthening procedures by hexapodal versus monorail external fixators. The hypothesis was that the hexapodal fixator provides more precise correction. A retrospective multicenter study included 52 children with fibular hypoplasia. Seventy-two tibias were analyzed, in 2 groups: 52 using a hexapodal fixator, and 20 using a monorail fixator. Mean age was 10.2 years. Mean lengthening was 5.7cm. Deformities were analyzed and measured in 3 dimensions and classified in 4 preoperative types and 4 post-lengthening types according to residual deformity. Complete correction was achieved in 26 tibias in the hexapodal group (50%) and 2 tibias in the monorail group (10%). Mean post-correction mechanical axis deviation was smaller in the hexapodal group: 12.83mm, versus 14.29mm in the monorail group. Mean post-correction mechanical lateral distal femoral angle was 87.5° in the hexapodal group, versus 84.3° in the monorail group (P=0.002), and mean mechanical medial proximal tibial angle 86.9° versus 89.5°, respectively (P=0.015). No previous studies focused on this congenital pathology in lengthening and axial correction programs for childhood lower-limb deformity. The present study found the hexapodal fixator to be more effective in conserving or restoring mechanical axes during progressive bone lengthening for fibular hypoplasia. The hexapodal fixator met the requirements of limb-length equalization in childhood congenital lower-limb hypoplasia, providing better axial correction than the monorail fixator. IV. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

[Association between sleep and leukocyte telomere length in middle-aged and older adults].

PubMed

Liu, H F; Li, F; Wang, Y H; Chen, J H; Peng, D X; Chen, J; Tan, L H; Mi, X; Zhao, B H

2017-07-10

Objective: To understand the association between peripheral leukocytes telomere length (TL) and sleep in middle-aged and old adults. Methods: A total of 176 middle-aged and old adults were investigated by using the Pittsburgh Sleep Quality Index and questionnaire. TL was measured by fluorescence quantitative PCR. The correlation and regression analysis between sleep and telomere length was performed. Results: TL had a mean T/S ratio of 0.995±0.23. There was a negative correlation between TL and age ( r =-0.241, P =0.003). With increasing age, sleep quality became worse ( r =-0.230, P <0.01), the time to fall asleep became longer ( r =0.227, P <0.01), sleep duration was shorter ( r =-0.486, P <0.01), sleep efficiency became worse ( r =-0.226, P <0.01). After controlling for the effects of gender, age, marital status, income level, residence, smoking, drinking, physical exercise and disease status, multiple linear regression analysis indicated that sleep quality ( β =0.057, P <0.01), time to fall asleep ( β =-0.046, P <0.01), sleep duration ( β =0.086, P <0.01) were independent influencing factors of telomere length, suggesting that the people who had better sleep quality, the shorter time to fall asleep, the longer sleep time would have longer telomere length. Conclusions: Sleep is a relevant factor affecting TL in middle-aged and elderly population. Good sleep may delay aging by slowing TL. We encourage to conduct health education about the importance of sleep quality in community.

Ultrasonographic study on changes in axial eye dimensions after encircling procedure in retinal detachment surgery.

PubMed

Larsen, J S; Syrdalen, P

1979-06-01

The pre- and postoperative results of ultrasonographic measurements on the axial ocular components in 10 phakic eyes with retinal detachment treated with encircling silicone rubber band are presented. A significant increase (P less than 0.001) in axial eye length from 0.62 to 1.24 mm (average: 0.98 mm) was found. The elongation of the eye was caused by a corresponding increase in the length of the vitreous cavity. No significant changes were found in the anterior segment of the eyes. These data demonstrate that the postoperative refractive change in a myopic direction, which an encircling procedure with moderate indentation often produces, is caused by an axial elongation of the eye.

Design of graphene nanoparticle undergoing axial compression: quantum study

NASA Astrophysics Data System (ADS)

Glukhova, O. E.; Kirillova, I. V.; Saliy, I. N.; Kolesnikova, A. S.; Slepchenkov, M. M.

2011-03-01

We report the results of quantum mechanical investigations of the atomic structure and deformations of graphene nanoparticle undergoing axial compression. We applied the tight-binding (TB) method. Our transferable tightbinding potential correctly reproduced tight-binding changes in the electronic configuration as a function of the local bonding geometry around each carbon atom. The tight-binding method applied provided the consideration and calculation of the rehybridization between σ- and π-orbitals. To research nanoribbons using tight-binding potential our own program was used. We adapted TB method to be able to run the algorithm on a parallel computing machine (computer cluster). To simulate axial compression of graphene nanoparticles the atoms on the ends were fixed on the plates. The plates were moved towards each other to decrease the length at some percent. Plane atomic network undergoing axial compression became wave-like. The amplitude of wave and its period were not constant and changed along axis. This is a phase transition. The strain energy collapse occurs at the value of axial compression 0.03-0.04. The strain energy increased up to the quantity compression 0.03, then collapsed sharply and decreased. So according to our theoretical investigation, the elasticity of graphene nanoparticles is more than the elasticity of nanotubes the same width and length. The curvature of the atomic network because of compression will decrease the reactivity of graphene nanoparticles. We have calculated the atomic structure and electronic structure of the compression graphene nanopaticle at each step of strain of axial compression. We have come to the conclusion that the wave-like graphenes adsorbing protein and nucleic acid are the effective nanosensors and bionanosensors.

Body weight status and telomere length in U.S. middle-aged and older adults.

PubMed

An, Ruopeng; Yan, Hai

Telomere length has been proposed as a biomarker of biological aging. This study examined the relationship between body weight status and telomere length in U.S. middle-aged and older adults. Nationally representative data (N=2749) came from the Health and Retirement Study. Linear regressions were performed to examine the relationship between baseline body weight status reported in 1992 and telomere length measured in 2008 in the overall sample and by sex and racial/ethnic groups, adjusted for individual characteristics. Baseline overweight (25kg/m 2 ≤body mass index [BMI]<30kg/m 2 ) and obesity (BMI≥30kg/m 2 ) status positively predicted telomere length 17 years later. Compared with their normal weight counterparts, telomere length ratio was on average 0.062 (95% confidence interval=0.016, 0.109) and 0.125 (0.048, 0.202) larger among overweight and obese adults, respectively. In comparison to women and racial/ethnic minorities, the estimated positive associations between overweight and obesity status and telomere length were more salient among men and non-Hispanic whites, respectively. The positive association between body weight status and telomere length found in this study was opposite to what existing biological model predicts, and could partially relate to the nonlinear relationship between body weight status and telomere length across age cohorts, and/or the lack of reliability of BMI as an indicator for adiposity in the older population. Large-scale longitudinal studies with baseline telomere length measures are warranted to replicate this study finding and explore the potential heterogeneous relationship between body weight status and telomere length. Copyright © 2016 Asia Oceania Association for the Study of Obesity. Published by Elsevier Ltd. All rights reserved.

Is Telomere Length a Biomarker for Aging: Cross-Sectional Evidence from the West of Scotland?

PubMed Central

Der, Geoff; Batty, G. David; Benzeval, Michaela; Deary, Ian J.; Green, Michael J.; McGlynn, Liane; McIntyre, Alan; Robertson, Tony; Shiels, Paul G.

2012-01-01

Background The search for biomarkers of aging (BoAs) has been largely unsuccessful to-date and there is widespread skepticism about the prospects of finding any that satisfy the criteria developed by the American Federation of Aging Research. This may be because the criteria are too strict or because a composite measure might be more appropriate. Telomere length has attracted a great deal of attention as a candidate BoA. We investigate whether it meets the criteria to be considered as a single biomarker of aging, and whether it makes a useful contribution to a composite measure. Methodology/Principal Findings Using data from a large population based study, we show that telomere length is associated with age, with several measures of physical and cognitive functioning that are related to normal aging, and with three measures of overall health. In the majority of cases, telomere length adds predictive power to that of age, although it was not nearly as good a predictor overall. We used principal components analysis to form two composites from the measures of functioning, one including telomere length and the other not including it. These composite BoAs were better predictors of the health outcomes than chronological age. There was little difference between the two composites. Conclusions Telomere length does not satisfy the strict criteria for a BoA, but does add predictive power to that of chronological age. Equivocal results from previous studies might be due to lack of power or the choice of measures examined together with a focus on single biomarkers. Composite biomarkers of aging have the potential to outperform age and should be considered for future research in this area. PMID:23028820

Is telomere length a biomarker for aging: cross-sectional evidence from the west of Scotland?

PubMed

Der, Geoff; Batty, G David; Benzeval, Michaela; Deary, Ian J; Green, Michael J; McGlynn, Liane; McIntyre, Alan; Robertson, Tony; Shiels, Paul G

2012-01-01

The search for biomarkers of aging (BoAs) has been largely unsuccessful to-date and there is widespread skepticism about the prospects of finding any that satisfy the criteria developed by the American Federation of Aging Research. This may be because the criteria are too strict or because a composite measure might be more appropriate. Telomere length has attracted a great deal of attention as a candidate BoA. We investigate whether it meets the criteria to be considered as a single biomarker of aging, and whether it makes a useful contribution to a composite measure. Using data from a large population based study, we show that telomere length is associated with age, with several measures of physical and cognitive functioning that are related to normal aging, and with three measures of overall health. In the majority of cases, telomere length adds predictive power to that of age, although it was not nearly as good a predictor overall. We used principal components analysis to form two composites from the measures of functioning, one including telomere length and the other not including it. These composite BoAs were better predictors of the health outcomes than chronological age. There was little difference between the two composites. Telomere length does not satisfy the strict criteria for a BoA, but does add predictive power to that of chronological age. Equivocal results from previous studies might be due to lack of power or the choice of measures examined together with a focus on single biomarkers. Composite biomarkers of aging have the potential to outperform age and should be considered for future research in this area.

Spontaneous axial myopia and emmetropization in a strain of wild-type guinea pig (Cavia porcellus).

PubMed

Jiang, Liqin; Schaeffel, Frank; Zhou, Xiangtian; Zhang, Sen; Jin, Xi; Pan, Miaozhen; Ye, Lingying; Wu, Xiaomin; Huang, Qinzhu; Lu, Fan; Qu, Jia

2009-03-01

To describe a wild-type guinea pig strain with an incidence of spontaneous axial myopia, minimal pupil responses, lack of accommodation, and apparently normal spatial vision. Such a strain is of interest because it may permit the exploration of defective emmetropization and mapping of the underlying quantitative trait loci. Twenty-eight guinea pigs were selected from 220 animals based on binocular myopia (exceeding -1.50 diopter [D]) or anisometropia (difference between both eyes exceeding 10 D) at 4 weeks of age. Refractions and pupil responses were measured with eccentric infrared photoretinoscopy, corneal curvature by modified conventional keratometer, and axial lengths by A-scan ultrasonography once a week. Twenty-one guinea pigs were raised under a normal 12-hour light/12-hour dark cycle. From a sample of 18 anisometropic guinea pigs, 11 were raised under normal light cycle and 7 were raised in the dark to determine the extent to which visual input guides emmetropization. Spatial vision was tested in an automated optomotor drum. In 10 guinea pigs with myopia in both eyes, refractive errors ranged from -15.67 D to -1.50 D at 3 weeks with a high interocular correlation (R = 0.82); axial length and corneal curvature grew almost linearly over time. Strikingly, two patterns of recovery were observed in anisometropic guinea pigs: in 12 (67%) anisometropia persisted, and in 6 (33%) it declined over time. These ratios remained similar in dark-reared guinea pigs. Unlike published strains, all guinea pigs of this strain showed weak pupil responses and no signs of accommodation but up to 3 cyc/deg of spatial resolution. This strain of guinea pigs has spontaneous axial refractive errors that may be genetically or epigenetically determined. Interestingly, it differs from other published strains that show no refractive errors, vivid accommodation, or pupil responses.

Shorter telomere length increases age-related tumor risks in von Hippel-Lindau disease patients.

PubMed

Wang, Jiang-Yi; Peng, Shuang-He; Ning, Xiang-Hui; Li, Teng; Liu, Sheng-Jie; Liu, Jia-Yuan; Hong, Bao-An; Qi, Nie-Nie; Peng, Xiang; Zhou, Bo-Wen; Zhang, Jiu-Feng; Cai, Lin; Gong, Kan

2017-09-01

Von Hippel-Lindau (VHL) disease is a rare autosomal dominant cancer syndrome caused by alterations of VHL gene. Patients are predisposed to develop pheochromocytomas and solid or cystic tumors of the central nervous system, kidney, pancreas, and retina. Remarkable phenotypic heterogeneity exits in organ involvement and tumor onset age between and within VHL families. However, no reliable markers have been found to predict the age-related tumor risks in VHL patients. A large Chinese cohort composed of 300 VHL patients and 92 healthy family controls was enrolled in our study. Blood relative telomere length was measured in 184 patients and all the controls available for genomic DNA samples. Age-related risks for the five major VHL-associated tumors were evaluated using Kaplan-Meier plots and Cox regression analysis. Differences in clinical phenotype were observed between Chinese cohort and the United Kingdom cohort. VHL patients showed significantly shorter telomere length than healthy family controls(P = 0.0183), and a positive correlation was found between telomere length and onset age of the five major tumors, respectively. Moreover, patients in the shorter telomere group (age-adjusted telomere length ≤ 0.44) suffered higher age-related risks for VHL-associated central nervous system hemangioblastomas (HR: 1.879, P = 0.004), renal cell carcinoma (HR: 2.126, P = 0.002) and pancreatic cyst and neuroendocrine tumors (HR: 2.093, P = 0.001). These results indicate that blood shorter telomere length is a new biomarker for age-related tumor risks in VHL patients, which will be crucial to genetic counseling and future research about the role of telomere shortening in the pathogenesis of VHL-associated tumors. © 2017 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.

Telomere length and early severe social deprivation: linking early adversity and cellular aging

PubMed Central

Drury, SS; Theall, K; Gleason, MM; Smyke, AT; De Vivo, I; Wong, JYY; Fox, NA; Zeanah, CH; Nelson, CA

2012-01-01

Accelerated telomere length attrition has been associated with psychological stress and early adversity in adults; however, no studies have examined whether telomere length in childhood is associated with early experiences. The Bucharest Early Intervention Project is a unique randomized controlled trial of foster care placement compared with continued care in institutions. As a result of the study design, participants were exposed to a quantified range of time in institutional care, and represented an ideal population in which to examine the association between a specific early adversity, institutional care and telomere length. We examined the association between average relative telomere length, telomere repeat copy number to single gene copy number (T/S) ratio and exposure to institutional care quantified as the percent of time at baseline (mean age 22 months) and at 54 months of age that each child lived in the institution. A significant negative correlation between T/S ratio and percentage of time was observed. Children with greater exposure to institutional care had significantly shorter relative telomere length in middle childhood. Gender modified this main effect. The percentage of time in institutional care at baseline significantly predicted telomere length in females, whereas the percentage of institutional care at 54 months was strongly predictive of telomere length in males. This is the first study to demonstrate an association between telomere length and institutionalization, the first study to find an association between adversity and telomere length in children, and contributes to the growing literature linking telomere length and early adversity. PMID:21577215

Effect of Variable Chord Length on Transonic Axial Rotor Performance Investigated

NASA Technical Reports Server (NTRS)

Suder, Kenneth L.

2002-01-01

During the life of any gas turbine, blade erosion is present, especially for those units that are exposed to unfiltered air, such as aviation turbofan engines. The effect of this erosion is to reduce the blade chord progressively from the midspan to the tip region and to roughen and distort the blade surface. The effects of roughness on rotor performance have been documented by Suder et al. and Roberts. These papers indicate that the penalty for leading-edge roughness and erosion can be significant. Turbofan operators, therefore, restore chord length at routine maintenance intervals to regain performance before deterioration is too severe to salvage blades. As the rotor blades erode, the leading edge becomes rough - blunt and distorted from the nominal shape - and the aerodynamic performance suffers. Nominal performance can be recovered by recontouring the leading edges. This process, which inherently shortens the blade chord, can be used until the blade chord erodes to the stall limit. Below this chord length, which varies among engine-compressor types, a decrease of stall margin is likely. After compressor blade rework that includes leading edge recontouring, the blades have different chord lengths, ranging from blades that are near nominal chord length down to those near the stall chord limit. Furthermore, as blades erode below the stall limit, they must be replaced with new blades that have the full nominal chord length. Consequently, a set of compressor blades with varying chord lengths will be installed into each turbofan engine that goes through a complete maintenance cycle. The question arises, "Does fan or compressor performance depend on the order in which mixed-chord blades are installed into a fan or compressor disk?"

Effects of Step Length, Age, and Fall History on Hip and Knee Kinetics and Knee Co-contraction during the Maximum Step Length Test

PubMed Central

Schulz, Brian W.; Jongprasithporn, Manutchanok; Hart-Hughes, Stephanie J.; Bulat, Tatjana

2017-01-01

Background Maximum step length is a brief clinical test involving stepping out and back as far as possible with the arms folded across the chest. This test has been shown to predict fall risk, but the biomechanics of this test are not fully understood. Knee and hip kinetics (moments and powers) are greater for longer steps and for younger subjects, but younger subjects also step farther. Methods To separate effects of step length, age, and fall history on joint kinetics; 14 healthy younger, 14 older non-fallers, and 11 older fallers (27(5), 72(5), 75(6) years respectively) all stepped to the same relative target distances of 20-80% of their height. Knee and hip kinetics and knee co-contraction were calculated. Findings Hip and knee kinetics and knee co-contraction all increased with step length, but older non-fallers and fallers utilized greater stepping hip and less stepping knee extensor kinetics. Fallers had greater stepping knee co-contraction than non-fallers. Stance knee co-contraction of non-fallers was similar to young for shorter steps and similar to fallers for longer steps. Interpretation Age had minimal effects and fall history had no effects on joint kinetics of steps to similar distances. Effects of age and fall history on knee co-contraction may contribute to age-related kinetic differences and shorter maximal step lengths of older non-fallers and fallers, but step length correlated with every variable tested. Thus, declines in maximum step length could indicate declines in hip and knee extensor kinetics and impaired performance on similar tasks like recovering from a trip. PMID:23978310

Whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography

PubMed Central

Zhong, Jianguang; Tao, Aizhu; Xu, Zhe; Jiang, Hong; Shao, Yilei; Zhang, Huicheng; Liu, Che; Wang, Jianhua

2014-01-01

PURPOSE To investigate changes of whole eye axial biometry during accommodation using ultra-long scan depth optical coherence tomography (UL-OCT). DESIGN Prospective, observational case series. METHODS Twenty-one adult subjects were enrolled. Using UL-OCT, the left eye of each subject was imaged with relaxed (0 D) and accommodative stimuli (+6 D). Full eye biometry included central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness, vitreous length and axial length (AL). RESULTS During accommodation (+6 D), the axial biometry of the whole eye changed significantly. Compared to the rest state, ACD at the accommodative state decreased significantly from 3.128 ± 0.305 mm to 2.961 ± 0.298 mm (paired t-test, P < 0.001). The lens thickness increased significantly from 3.723 ± 0.237 mm to 3.963 ± 0.234 mm (P < 0.001). The vitreous length decreased significantly from 17.129 ± 0.864 mm to 17.057± 0.848 mm (P < 0.001). AL was 24.519 ± 0.917 mm at the rest state and increased to 24.545±0.915 mm with +6 D accommodation stimulus. The elongated AL of 26.1 ± 13.4 μm between the rest and accommodative states was significant (P < 0.001). CONCLUSIONS During accommodation, whole eye axial biometry changed, including a decrease in ACD and vitreous length, and an increase in lens thickness and AL. UL-OCT provides an alternative method that is suitable for full eye biometry during accommodation. PMID:24487051

The Relationship between Anterior Chamber Depth, Axial Length and Intraocular Lens Power among Candidates for Cataract Surgery.

PubMed

Sedaghat, Mohammad Reza; Azimi, Ali; Arasteh, Peyman; Tehranian, Naghmeh; Bamdad, Shahram

2016-10-01

Basic anatomical parameters in ophthalmology are variable in different countries according to ethnic groups, genetics and some environmental factors. The aim of this study was to determine the relationship between axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOL) in a referral center from eastern Iran among patients who had cataract surgery, in comparison to studies from other regions of the world. In a cross-sectional retrospective study from 2011 to 2013, the records of 698 cataract patients referring to Khatam Al Anbia general hospital in Mashhad, Iran were evaluated. We divided patients, based on their AL and ACD, into three separate groups and compared their results. The SPSS software was used for data analysis. The Chi-Square test and the Independent-samples t-test were used to compare qualitative and quantitative data between two groups, respectively. The Kendall and the Pearson product-moment correlation tests were used to assess the relationship between AL and ACD. The linear Regression model was used to obtain a mathematical model to estimate ACD, using AL, age and sex. Among individuals who had normal AL (between 22-24.5mm), there was a positive correlation between AL and ACD (p<0.001, r=0.17), however, among individuals with short (AL<22mm) or long sightedness (AL>24.5mm), no significant correlation was detected. We also found that older people have shorter AL (p=0.001 and r=-0.287). Men have an average longer AL (23.7±2.4mm vs. 22.9±2.1mm; p<0.001) and deeper ACD compared to women (2.93±0.45mm vs. 2.82±0.42mm, p=0.002). Our findings were mostly similar to previous literature from other regions of the world and although some anatomical variations may exist regarding ophthalmic anatomy, factors like race and geographical area have little effect on the relationship between ACD, AL and IOL power calculation, furthermore our results support the use of third and fourth generation formulas for IOL power calculation.

Is socioeconomic status associated with biological aging as measured by telomere length?

PubMed

Robertson, Tony; Batty, G David; Der, Geoff; Fenton, Candida; Shiels, Paul G; Benzeval, Michaela

2013-01-01

It has been hypothesized that one way in which lower socioeconomic status (SES) affects health is by increasing the rate of biological aging. A widely used marker of biological aging is telomere length. Telomeres are structures at the ends of chromosomes that erode with increasing cell proliferation and genetic damage. We aimed to identify, through systematic review and meta-analysis, whether lower SES (greater deprivation) is associated with shorter telomeres. Thirty-one articles, including 29 study populations, were identified. We conducted 3 meta-analyses to compare the telomere lengths of persons of high and low SES with regard to contemporaneous SES (12 study populations from 10 individual articles), education (15 study populations from 14 articles), and childhood SES (2 study populations from 2 articles). For education, there was a significant difference in telomere length between persons of high and low SES in a random-effects model (standardized mean difference (SMD) = 0.060, 95% confidence interval (CI): 0.002, 0.118; P = 0.042), although a range of sensitivity analyses weakened this association. There was no evidence for an association between telomere length and contemporaneous SES (SMD = 0.104, 95% CI: -0.027, 0.236; P = 0.119) or childhood SES (SMD = -0.037, 95% CI: -0.143, 0.069; P = 0.491). These results suggest weak evidence for an association between SES (as measured by education) and biological aging (as measured by telomere length), although there was a lack of consistent findings across the SES measures investigated here. © The Author 2012. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health.

Estimating age from recapture data: integrating incremental growth measures with ancillary data to infer age-at-length

USGS Publications Warehouse

Eaton, Mitchell J.; Link, William A.

2011-01-01

Estimating the age of individuals in wild populations can be of fundamental importance for answering ecological questions, modeling population demographics, and managing exploited or threatened species. Significant effort has been devoted to determining age through the use of growth annuli, secondary physical characteristics related to age, and growth models. Many species, however, either do not exhibit physical characteristics useful for independent age validation or are too rare to justify sacrificing a large number of individuals to establish the relationship between size and age. Length-at-age models are well represented in the fisheries and other wildlife management literature. Many of these models overlook variation in growth rates of individuals and consider growth parameters as population parameters. More recent models have taken advantage of hierarchical structuring of parameters and Bayesian inference methods to allow for variation among individuals as functions of environmental covariates or individual-specific random effects. Here, we describe hierarchical models in which growth curves vary as individual-specific stochastic processes, and we show how these models can be fit using capture–recapture data for animals of unknown age along with data for animals of known age. We combine these independent data sources in a Bayesian analysis, distinguishing natural variation (among and within individuals) from measurement error. We illustrate using data for African dwarf crocodiles, comparing von Bertalanffy and logistic growth models. The analysis provides the means of predicting crocodile age, given a single measurement of head length. The von Bertalanffy was much better supported than the logistic growth model and predicted that dwarf crocodiles grow from 19.4 cm total length at birth to 32.9 cm in the first year and 45.3 cm by the end of their second year. Based on the minimum size of females observed with hatchlings, reproductive maturity was estimated

Axial displacements in external and internal implant-abutment connection.

PubMed

Lee, Ji-Hye; Kim, Dae-Gon; Park, Chan-Jin; Cho, Lee-Ra

2014-02-01

The purpose of this study was to evaluate the axial displacement of the abutments during clinical procedures by the tightening torque and cyclic loading. Two different implant-abutment connection systems were used (external butt joint connection [EXT]; internal tapered conical connection [INT]). The master casts with two implant replicas, angulated 10° from each other, were fabricated for each implant connection system. Four types of impression copings were assembled and tightened with the corresponding implants (hex transfer impression coping, non-hex transfer impression coping, hex pick-up impression coping, non-hex pick-up impression coping). Resin splinted abutments and final prosthesis were assembled. The axial displacement was measured from the length of each assembly, which was evaluated repeatedly, after 30 Ncm torque tightening. After 250 N cyclic loading of final prosthesis for 1,000,000 cycles, additional axial displacement was recorded. The mean axial displacement was statistically analyzed (repeated measured ANOVA). There was more axial displacement in the INT group than that of the EXT group in impression copings, resin splinted abutments, and final prosthesis. Less axial displacement was found at 1-piece non-hex transfer type impression coping than other type of impression copings in the INT group. There was more axial displacement at the final prosthesis than resin splinted abutments in the INT and the EXT groups. After 250 N cyclic loading of final prosthesis, the INT group showed more axial displacement than that of the EXT group. Internal tapered conical connection demonstrated a varying amount of axial displacement with tightening torque and cyclic loading. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.

Canine Length in Wild Male Baboons: Maturation, Aging and Social Dominance Rank

PubMed Central

Galbany, Jordi; Tung, Jenny; Altmann, Jeanne; Alberts, Susan C.

2015-01-01

Canines represent an essential component of the dentition for any heterodont mammal. In primates, like many other mammals, canines are frequently used as weapons. Hence, tooth size and wear may have significant implications for fighting ability, and consequently for social dominance rank, reproductive success, and fitness. We evaluated sources of variance in canine growth and length in a well-studied wild primate population because of the potential importance of canines for male reproductive success in many primates. Specifically, we measured maxillary canine length in 80 wild male baboons (aged 5.04–20.45 years) from the Amboseli ecosystem in southern Kenya, and examined its relationship with maturation, age, and social dominance rank. In our analysis of maturation, we compared food-enhanced baboons (those that fed part time at a refuse pit associated with a tourist lodge) with wild-feeding males, and found that food-enhanced males achieved long canines earlier than wild-feeding males. Among adult males, canine length decreased with age because of tooth wear. We found some evidence that, after controlling for age, longer canines were associated with higher adult dominance rank (accounting for 9% of the variance in rank), but only among relatively high-ranking males. This result supports the idea that social rank, and thus reproductive success and fitness, may depend in part on fighting ability mediated by canine size. PMID:25950700

A single-cell assay for telomere DNA content shows increasing telomere length heterogeneity, as well as increasing mean telomere length in human spermatozoa with advancing age.

PubMed

Antunes, Danielle M F; Kalmbach, Keri H; Wang, Fang; Dracxler, Roberta C; Seth-Smith, Michelle L; Kramer, Yael; Buldo-Licciardi, Julia; Kohlrausch, Fabiana B; Keefe, David L

2015-11-01

The effect of age on telomere length heterogeneity in men has not been studied previously. Our aims were to determine the relationship between variation in sperm telomere length (STL), men's age, and semen parameters in spermatozoa from men undergoing in vitro fertilization (IVF) treatment. To perform this prospective cross-sectional pilot study, telomere length was estimated in 200 individual spermatozoa from men undergoing IVF treatment at the NYU Fertility Center. A novel single-cell telomere content assay (SCT-pqPCR) measured telomere length in individual spermatozoa. Telomere length among individual spermatozoa within an ejaculate varies markedly and increases with age. Older men not only have longer STL but also have more variable STL compared to younger men. STL from samples with normal semen parameters was significantly longer than that from samples with abnormal parameters, but STL did not differ between spermatozoa with normal versus abnormal morphology. The marked increase in STL heterogeneity as men age is consistent with a role for ALT during spermatogenesis. No data have yet reported the effect of age on STL heterogeneity. Based on these results, future studies should expand this modest sample size to search for molecular evidence of ALT in human testes during spermatogenesis.

Nonlinear Response of Thin Cylindrical Shells with Longitudinal Cracks and Subjected to Internal Pressure and Axial compression Loads

NASA Technical Reports Server (NTRS)

Starnes, James H.; Rose, Cheryl A.

1998-01-01

The results of an analytical study of the nonlinear response of a thin unstiffened aluminum cylindrical shell with a longitudinal crack are presented. The shell is analyzed with a nonlinear shell analysis code that maintains the shell in a nonlinear equilibrium state while the crack is grown. The analysis accurately accounts for global and local structural response phenomena. Results are presented for internal pressure, axial compression, and combined internal pressure and axial compression loads. The effects of varying crack length on the nonlinear response of the shell subjected to internal pressure are described. The effects of varying crack length on the prebuckling, buckling and postbuckling responses of the shell subjected to axial compression, and subjected to combined internal pressure and axial compression are also described. The results indicate that the nonlinear interaction between the in-plane stress resultants and the out-of-plane displacements near a crack can significantly affect the structural response of the shell. The results also indicate that crack growth instabilities and shell buckling instabilities can both affect the response of the shell as the crack length is increased.

In vivo evaluation of axial integrity of coronary stents using intravascular ultrasound: Insights on longitudinal stent deformation.

PubMed

Dvir, Danny; Kitabata, Hironori; Barbash, Israel M; Minha, Sa'ar; Badr, Salem; Loh, Joshua P; Chen, Fang; Torguson, Rebecca; Waksman, Ron

2014-09-01

To evaluate the axial integrity of different coronary stents using intravascular ultrasound (IVUS). Longitudinal stent deformation was recently reported. Consecutive patients who underwent IVUS analysis after drug-eluting stent (DES) implantation for de novo coronary lesions were evaluated. Stent length was compared with label length for calculation of absolute change and relative difference (absolute change divided by label length). A total of 233 DES utilizing five different platforms were included. The median absolute change in stent length was 0.90 mm (interquartile range [IQR] 0.48-1.39) and the relative difference was 5.24% (IQR 2.55-8.29). There was no significant difference among the groups in median absolute or relative change: Cypher 0.89 mm/3.89%, Taxus 0.88 mm/5.39%, Endeavor 1.16 mm/6.77%, Xience V 0.86 mm/5.80%, and PROMUS Element 0.79 mm/5.34% (P = 0.085, P = 0.072, respectively). Multivariate logistic regression revealed that the Cypher stent was independently correlated with a lower change in length, whereas stent label length and deployment pressure were correlated with higher absolute change. The axial integrity of DES platforms examined in vivo was high, with only mild changes in stent length after implantation. While there are differences between first- and second-generation DES, axial integrity among second-generation DES was similar. © 2013 Wiley Periodicals, Inc.

Paternal age at birth is an important determinant of offspring telomere length.

PubMed

De Meyer, Tim; Rietzschel, Ernst R; De Buyzere, Marc L; De Bacquer, Dirk; Van Criekinge, Wim; De Backer, Guy G; Gillebert, Thierry C; Van Oostveldt, Patrick; Bekaert, Sofie

2007-12-15

Although evidence supports the function of telomere length (TL) as a marker for biological aging, no major determinants of TL are known besides inheritance, age and gender. Here we validate and, more importantly, assess the impact of paternal age at birth as a determinant for the offspring's peripheral blood leukocyte TL within the Asklepios study population. Telomere restriction fragment length and paternal age information were available for 2433 volunteers (1176 men and 1257 women) aged approximately 35-55 years old. Paternal age at birth was positively associated with offspring TL (offspring age and gender adjusted, P < 10 (-14)). The increase in TL was estimated at 17 base pairs for each supplemental year at birth and was not statistically different between male and female offspring. The effect size of paternal age outweighed the classical TL determinant gender by a factor of 2, demonstrating the large impact. Maternal age at birth was not independently associated with offspring TL. The peculiar interaction between paternal age at birth and inheritance might explain a large part of the genetic component of TL variance on a population level. This finding also provides further proof for the theory that TL is not completely reset in the zygote. Furthermore, as paternal age is subject to demographic evolution, its association with TL might have a substantial impact on the results and comparability of TL within and between epidemiological studies. In conclusion, paternal age is an important determinant for TL, with substantial consequences for future studies.

Evaluation of Eyeball and Orbit in Relation to Gender and Age.

PubMed

Özer, Cenk Murat; Öz, Ibrahim Ilker; Şerifoğlu, Ismail; Büyükuysal, Mustafa Çağatay; Barut, Çağatay

2016-11-01

The orbital aperture is the entrance to the orbit in which most important visual structures such as the eyeball and the optic nerve are found. It is vital not only for the visual system but also for the evaluation and recognition of the face. Eyeball volume is essential for diagnosing microphthalmos or buphthalmos in several eye disorders. Knowing the length of the optic nerve is necessary in selecting the right instruments for enucleation. Therefore, the aim of this study was to evaluate eyeball volume, orbital aperture, and optic nerve dimensions for a morphological description in a Turkish population sample according to gender and body side.Paranasal sinus computed tomography (CT) scans of 198 individuals (83 females, 115 males) aged between 5 and 74 years were evaluated retrospectively. The dimensions of orbital aperture, axial length and volume of eyeball, and diameter and length of the intraorbital part of the optic nerve were measured. Computed tomography examinations were performed on an Activion 16 CT Scanner (Toshiba Medical Systems, 2008 Japan). The CT measurements were calculated by using OsiriX software on a personal computer. All parameters were evaluated according to gender and right/left sides. A statistically significant difference between genders was found with respect to axial length of eyeball, optic nerve diameter, dimensions of orbital aperture on both sides, and right optic nerve length. Furthermore, certain statistically significant side differences were also found. There were statistically significant correlations between age and the axial length of the eyeball, optic nerve diameter, and the transverse length of the orbital aperture on both sides for the whole study group.In this study we determined certain morphometric parameters of the orbit. These outcomes may be helpful in developing a database to determine normal orbit values for the Turkish population so that quantitative assessment of orbital disease and orbital deformities will be

The Axial Age and the Problems of the Twentieth Century: Du Bois, Jaspers, and Universal History.

PubMed

Boy, John D

The axial age debate has put big questions of social and cultural change back on the agenda of sociology. This paper takes this development as an occasion to reflect on how social thought works with (and against) nineteenth-century intellectual traditions in its efforts to understand history on a macro scale. Karl Jaspers, who initially formulated the axial age thesis in The Origin and Goal of History , revised the Hegelian account of world history by broadening the scope of the narrative to encompass all civilizations participating in the events of the first millennium BCE that saw the rise of major philosophical and religious traditions. However, his account, like the earlier philosophical accounts he seeks to improve upon, privileges cognitive developments over material practices and social interactions, and as such offers little to those seeking to make sense of how cultural patterns interact with others and spread. Here another social theorist engaging with Hegel, W. E. B. Du Bois, provides a helpful contrast. His account of the development of double-consciousness in "Of Our Spiritual Strivings," the opening chapter of The Souls of Black Folk , helps us to understand experiences of encounter and the perduring historical effects they may have. Du Bois' relational theory reminds us of the importance of unpacking abstractions and understanding processes in terms of social interactions.

Myopia and/or longer axial length are protective against diabetic retinopathy: a meta-analysis.

PubMed

Fu, Yu; Geng, Dengfeng; Liu, Hua; Che, Huixin

2016-06-01

To evaluate the current evidence of the relationship between myopia, together with its structural and refractive component, and diabetic retinopathy (DR) risk. A systematic search was performed up to April, 2015. Summary odds ratios (ORs) and 95% confidence intervals (CIs) were calculated employing random-effects models. Three models were used to assess the association between myopia and risk of DR: axial length (AL) (per millimetre increase) and DR; myopia (myopia versus non-myopia) and DR; refractive error (RE) (per D decrease) and DR. Publication bias of the literature was evaluated using Begg's funnel plots and Egger's test. A total of 11 studies that met the predefined criteria were included in this meta-analysis. Overall, longer AL (per millimetre increase) was associa-ted with a significantly decreased risk of DR (combined OR, 0.75; 95% CI, 0.65-0.86; p < 0.001); myopic eyes (myopia versus non-myopia) showed a lower risk of DR (combined OR, 0.70; 95% CI, 0.58-0.85; p < 0.001). A greater degree of myopic RE (per D decrease) also revealed a significantly decreased risk of DR (combined OR, 0.89; 95% CI, 0.85-0.93; p < 0.001). The sensitivity analyses and cumulative meta-analysis showed similar results. No publication bias was detected in any of the three models. This meta-analysis suggests that both myopic refraction and longer AL are associated with a lower risk of DR. Further studies are needed to determine exact mechanisms underpinning the protective effect of myopia against DR. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

A Comparative Study to Assess the Predictability of Different IOL Power Calculation Formulas in Eyes of Short and Long Axial Length.

PubMed

Doshi, Dharmil; Limdi, Purvi; Parekh, Nilesh; Gohil, Neepa

2017-01-01

Accurate Intraocular Lens (IOL) power calculation in cataract surgery is very important for providing postoperative precise vision. Selection of most appropriate formula is difficult in high myopic and hypermetropic patients. To investigate the predictability of different IOL (Intra Ocular Lens) power calculation formulae in eyes with short and long Axial Length (AL) and to find out most accurate IOL power calculation formula in both groups. A prospective study was conducted on 80 consecutive patients who underwent phacoemulsification with monofocal IOL implantation after obtaining an informed and written consent. Preoperative keratometry was done by IOL Master. Axial length and anterior chamber depth was measured using A-scan machine ECHORULE 2 (BIOMEDIX). Patients were divided into two groups based on AL. (40 in each group). Group A with AL<22 mm and Group B with AL>24.5 mm. The IOL power calculation in each group was done by Haigis, Hoffer Q, Holladay-I, SRK/T formulae using the software of ECHORULE 2. The actual postoperative Spherical Equivalent (SE), Estimation error (E) and Absolute Error (AE) were calculated at one and half months and were used in data analysis. The predictive accuracy of each formula in each group was analyzed by comparing the Absolute Error (AE). The Kruskal Wallis test was used to compare differences in the (AE) of the formulae. A statistically significant difference was defined as p-value<0.05. In Group A, Hoffer Q, Holladay 1 and SRK/T formulae were equally accurate in predicting the postoperative refraction after cataract surgery (IOL power calculation) in eyes with AL less than 22.0 mm and accuracy of these three formulae was significantly higher than Haigis formula. Whereas in Group B, Hoffer Q, Holladay 1, SRK/T and Haigis formulae were equally accurate in predicting the postoperative refraction after cataract surgery (IOL power calculation) in eyes with AL more than 24.5 mm. Hoffer Q, Holladay 1 and SRK/T formulae were showing

Nine Loci for Ocular Axial Length Identified through Genome-wide Association Studies, Including Shared Loci with Refractive Error

PubMed Central

Cheng, Ching-Yu; Schache, Maria; Ikram, M. Kamran; Young, Terri L.; Guggenheim, Jeremy A.; Vitart, Veronique; MacGregor, Stuart; Verhoeven, Virginie J.M.; Barathi, Veluchamy A.; Liao, Jiemin; Hysi, Pirro G.; Bailey-Wilson, Joan E.; St. Pourcain, Beate; Kemp, John P.; McMahon, George; Timpson, Nicholas J.; Evans, David M.; Montgomery, Grant W.; Mishra, Aniket; Wang, Ya Xing; Wang, Jie Jin; Rochtchina, Elena; Polasek, Ozren; Wright, Alan F.; Amin, Najaf; van Leeuwen, Elisabeth M.; Wilson, James F.; Pennell, Craig E.; van Duijn, Cornelia M.; de Jong, Paulus T.V.M.; Vingerling, Johannes R.; Zhou, Xin; Chen, Peng; Li, Ruoying; Tay, Wan-Ting; Zheng, Yingfeng; Chew, Merwyn; Rahi, Jugnoo S.; Hysi, Pirro G.; Yoshimura, Nagahisa; Yamashiro, Kenji; Miyake, Masahiro; Delcourt, Cécile; Maubaret, Cecilia; Williams, Cathy; Guggenheim, Jeremy A.; Northstone, Kate; Ring, Susan M.; Davey-Smith, George; Craig, Jamie E.; Burdon, Kathryn P.; Fogarty, Rhys D.; Iyengar, Sudha K.; Igo, Robert P.; Chew, Emily; Janmahasathian, Sarayut; Iyengar, Sudha K.; Igo, Robert P.; Chew, Emily; Janmahasathian, Sarayut; Stambolian, Dwight; Wilson, Joan E. Bailey; MacGregor, Stuart; Lu, Yi; Jonas, Jost B.; Xu, Liang; Saw, Seang-Mei; Baird, Paul N.; Rochtchina, Elena; Mitchell, Paul; Wang, Jie Jin; Jonas, Jost B.; Nangia, Vinay; Hayward, Caroline; Wright, Alan F.; Vitart, Veronique; Polasek, Ozren; Campbell, Harry; Vitart, Veronique; Rudan, Igor; Vatavuk, Zoran; Vitart, Veronique; Paterson, Andrew D.; Hosseini, S. Mohsen; Iyengar, Sudha K.; Igo, Robert P.; Fondran, Jeremy R.; Young, Terri L.; Feng, Sheng; Verhoeven, Virginie J.M.; Klaver, Caroline C.; van Duijn, Cornelia M.; Metspalu, Andres; Haller, Toomas; Mihailov, Evelin; Pärssinen, Olavi; Wedenoja, Juho; Wilson, Joan E. Bailey; Wojciechowski, Robert; Baird, Paul N.; Schache, Maria; Pfeiffer, Norbert; Höhn, René; Pang, Chi Pui; Chen, Peng; Meitinger, Thomas; Oexle, Konrad; Wegner, Aharon; Yoshimura, Nagahisa; Yamashiro, Kenji; Miyake, Masahiro; Pärssinen, Olavi; Yip, Shea Ping; Ho, Daniel W.H.; Pirastu, Mario; Murgia, Federico; Portas, Laura; Biino, Genevra; Wilson, James F.; Fleck, Brian; Vitart, Veronique; Stambolian, Dwight; Wilson, Joan E. Bailey; Hewitt, Alex W.; Ang, Wei; Verhoeven, Virginie J.M.; Klaver, Caroline C.; van Duijn, Cornelia M.; Saw, Seang-Mei; Wong, Tien-Yin; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Saw, Seang-Mei; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Saw, Seang-Mei; Wong, Tien-Yin; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Saw, Seang-Mei; Wong, Tien-Yin; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Saw, Seang-Mei; Tai, E-Shyong; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Saw, Seang-Mei; Teo, Yik-Ying; Fan, Qiao; Cheng, Ching-Yu; Zhou, Xin; Ikram, M. Kamran; Mackey, David A.; MacGregor, Stuart; Hammond, Christopher J.; Hysi, Pirro G.; Deangelis, Margaret M.; Morrison, Margaux; Zhou, Xiangtian; Chen, Wei; Paterson, Andrew D.; Hosseini, S. Mohsen; Mizuki, Nobuhisa; Meguro, Akira; Lehtimäki, Terho; Mäkelä, Kari-Matti; Raitakari, Olli; Kähönen, Mika; Burdon, Kathryn P.; Craig, Jamie E.; Iyengar, Sudha K.; Igo, Robert P.; Lass, Jonathan H.; Reinhart, William; Belin, Michael W.; Schultze, Robert L.; Morason, Todd; Sugar, Alan; Mian, Shahzad; Soong, Hunson Kaz; Colby, Kathryn; Jurkunas, Ula; Yee, Richard; Vital, Mark; Alfonso, Eduardo; Karp, Carol; Lee, Yunhee; Yoo, Sonia; Hammersmith, Kristin; Cohen, Elisabeth; Laibson, Peter; Rapuano, Christopher; Ayres, Brandon; Croasdale, Christopher; Caudill, James; Patel, Sanjay; Baratz, Keith; Bourne, William; Maguire, Leo; Sugar, Joel; Tu, Elmer; Djalilian, Ali; Mootha, Vinod; McCulley, James; Bowman, Wayne; Cavanaugh, H. Dwight; Verity, Steven; Verdier, David; Renucci, Ann; Oliva, Matt; Rotkis, Walter; Hardten, David R.; Fahmy, Ahmad; Brown, Marlene; Reeves, Sherman; Davis, Elizabeth A.; Lindstrom, Richard; Hauswirth, Scott; Hamilton, Stephen; Lee, W. Barry; Price, Francis; Price, Marianne; Kelly, Kathleen; Peters, Faye; Shaughnessy, Michael; Steinemann, Thomas; Dupps, B.J.; Meisler, David M.; Mifflin, Mark; Olson, Randal; Aldave, Anthony; Holland, Gary; Mondino, Bartly J.; Rosenwasser, George; Gorovoy, Mark; Dunn, Steven P.; Heidemann, David G.; Terry, Mark; Shamie, Neda; Rosenfeld, Steven I.; Suedekum, Brandon; Hwang, David; Stone, Donald; Chodosh, James; Galentine, Paul G.; Bardenstein, David; Goddard, Katrina; Chin, Hemin; Mannis, Mark; Varma, Rohit; Borecki, Ingrid; Chew, Emily Y.; Haller, Toomas; Mihailov, Evelin; Metspalu, Andres; Wedenoja, Juho; Simpson, Claire L.; Wojciechowski, Robert; Höhn, René; Mirshahi, Alireza; Zeller, Tanja; Pfeiffer, Norbert; Lackner, Karl J.; Donnelly, Peter; Barroso, Ines; Blackwell, Jenefer M.; Bramon, Elvira; Brown, Matthew A.; Casas, Juan P.; Corvin, Aiden; Deloukas, Panos; Duncanson, Audrey; Jankowski, Janusz; Markus, Hugh S.; Mathew, Christopher G.; Palmer, Colin N.A.; Plomin, Robert; Rautanen, Anna; Sawcer, Stephen J.; Trembath, Richard C.; Viswanathan, Ananth C.; Wood, Nicholas W.; Spencer, Chris C.A.; Band, Gavin; Bellenguez, Céline; Freeman, Colin; Hellenthal, Garrett; Giannoulatou, Eleni; Pirinen, Matti; Pearson, Richard; Strange, Amy; Su, Zhan; Vukcevic, Damjan; Donnelly, Peter; Langford, Cordelia; Hunt, Sarah E.; Edkins, Sarah; Gwilliam, Rhian; Blackburn, Hannah; Bumpstead, Suzannah J.; Dronov, Serge; Gillman, Matthew; Gray, Emma; Hammond, Naomi; Jayakumar, Alagurevathi; McCann, Owen T.; Liddle, Jennifer; Potter, Simon C.; Ravindrarajah, Radhi; Ricketts, Michelle; Waller, Matthew; Weston, Paul; Widaa, Sara; Whittaker, Pamela; Barroso, Ines; Deloukas, Panos; Mathew, Christopher G.; Blackwell, Jenefer M.; Brown, Matthew A.; Corvin, Aiden; Spencer, Chris C.A.; Bettecken, Thomas; Meitinger, Thomas; Oexle, Konrad; Pirastu, Mario; Portas, Laura; Nag, Abhishek; Williams, Katie M.; Yonova-Doing, Ekaterina; Klein, Ronald; Klein, Barbara E.; Hosseini, S. Mohsen; Paterson, Andrew D.; Genuth, S.; Nathan, D.M.; Zinman, B.; Crofford, O.; Crandall, J.; Reid, M.; Brown-Friday, J.; Engel, S.; Sheindlin, J.; Martinez, H.; Shamoon, H.; Engel, H.; Phillips, M.; Gubitosi-Klug, R.; Mayer, L.; Pendegast, S.; Zegarra, H.; Miller, D.; Singerman, L.; Smith-Brewer, S.; Novak, M.; Quin, J.; Dahms, W.; Genuth, Saul; Palmert, M.; Brillon, D.; Lackaye, M.E.; Kiss, S.; Chan, R.; Reppucci, V.; Lee, T.; Heinemann, M.; Whitehouse, F.; Kruger, D.; Jones, J.K.; McLellan, M.; Carey, J.D.; Angus, E.; Thomas, A.; Galprin, A.; Bergenstal, R.; Johnson, M.; Spencer, M.; Morgan, K.; Etzwiler, D.; Kendall, D.; Aiello, Lloyd Paul; Golden, E.; Jacobson, A.; Beaser, R.; Ganda, O.; Hamdy, O.; Wolpert, H.; Sharuk, G.; Arrigg, P.; Schlossman, D.; Rosenzwieg, J.; Rand, L.; Nathan, D.M.; Larkin, M.; Ong, M.; Godine, J.; Cagliero, E.; Lou, P.; Folino, K.; Fritz, S.; Crowell, S.; Hansen, K.; Gauthier-Kelly, C.; Service, J.; Ziegler, G.; Luttrell, L.; Caulder, S.; Lopes-Virella, M.; Colwell, J.; Soule, J.; Fernandes, J.; Hermayer, K.; Kwon, S.; Brabham, M.; Blevins, A.; Parker, J.; Lee, D.; Patel, N.; Pittman, C.; Lindsey, P.; Bracey, M.; Lee, K.; Nutaitis, M.; Farr, A.; Elsing, S.; Thompson, T.; Selby, J.; Lyons, T.; Yacoub-Wasef, S.; Szpiech, M.; Wood, D.; Mayfield, R.; Molitch, M.; Schaefer, B.; Jampol, L.; Lyon, A.; Gill, M.; Strugula, Z.; Kaminski, L.; Mirza, R.; Simjanoski, E.; Ryan, D.; Kolterman, O.; Lorenzi, G.; Goldbaum, M.; Sivitz, W.; Bayless, M.; Counts, D.; Johnsonbaugh, S.; Hebdon, M.; Salemi, P.; Liss, R.; Donner, T.; Gordon, J.; Hemady, R.; Kowarski, A.; Ostrowski, D.; Steidl, S.; Jones, B.; Herman, W.H.; Martin, C.L.; Pop-Busui, R.; Sarma, A.; Albers, J.; Feldman, E.; Kim, K.; Elner, S.; Comer, G.; Gardner, T.; Hackel, R.; Prusak, R.; Goings, L.; Smith, A.; Gothrup, J.; Titus, P.; Lee, J.; Brandle, M.; Prosser, L.; Greene, D.A.; Stevens, M.J.; Vine, A.K.; Bantle, J.; Wimmergren, N.; Cochrane, A.; Olsen, T.; Steuer, E.; Rath, P.; Rogness, B.; Hainsworth, D.; Goldstein, D.; Hitt, S.; Giangiacomo, J.; Schade, D.S.; Canady, J.L.; Chapin, J.E.; Ketai, L.H.; Braunstein, C.S.; Bourne, P.A.; Schwartz, S.; Brucker, A.; Maschak-Carey, B.J.; Baker, L.; Orchard, T.; Silvers, N.; Ryan, C.; Songer, T.; Doft, B.; Olson, S.; Bergren, R.L.; Lobes, L.; Rath, P. Paczan; Becker, D.; Rubinstein, D.; Conrad, P.W.; Yalamanchi, S.; Drash, A.; Morrison, A.; Bernal, M.L.; Vaccaro-Kish, J.; Malone, J.; Pavan, P.R.; Grove, N.; Iyer, M.N.; Burrows, A.F.; Tanaka, E.A.; Gstalder, R.; Dagogo-Jack, S.; Wigley, C.; Ricks, H.; Kitabchi, A.; Murphy, M.B.; Moser, S.; Meyer, D.; Iannacone, A.; Chaum, E.; Yoser, S.; Bryer-Ash, M.; Schussler, S.; Lambeth, H.; Raskin, P.; Strowig, S.; Zinman, B.; Barnie, A.; Devenyi, R.; Mandelcorn, M.; Brent, M.; Rogers, S.; Gordon, A.; Palmer, J.; Catton, S.; Brunzell, J.; Wessells, H.; de Boer, I.H.; Hokanson, J.; Purnell, J.; Ginsberg, J.; Kinyoun, J.; Deeb, S.; Weiss, M.; Meekins, G.; Distad, J.; Van Ottingham, L.; Dupre, J.; Harth, J.; Nicolle, D.; Driscoll, M.; Mahon, J.; Canny, C.; May, M.; Lipps, J.; Agarwal, A.; Adkins, T.; Survant, L.; Pate, R.L.; Munn, G.E.; Lorenz, R.; Feman, S.; White, N.; Levandoski, L.; Boniuk, I.; Grand, G.; Thomas, M.; Joseph, D.D.; Blinder, K.; Shah, G.; Boniuk; Burgess; Santiago, J.; Tamborlane, W.; Gatcomb, P.; Stoessel, K.; Taylor, K.; Goldstein, J.; Novella, S.; Mojibian, H.; Cornfeld, D.; Lima, J.; Bluemke, D.; Turkbey, E.; van der Geest, R.J.; Liu, C.; Malayeri, A.; Jain, A.; Miao, C.; Chahal, H.; Jarboe, R.; Maynard, J.; Gubitosi-Klug, R.; Quin, J.; Gaston, P.; Palmert, M.; Trail, R.; Dahms, W.; Lachin, J.; Cleary, P.; Backlund, J.; Sun, W.; Braffett, B.; Klumpp, K.; Chan, K.; Diminick, L.; Rosenberg, D.; Petty, B.; Determan, A.; Kenny, D.; Rutledge, B.; Younes, Naji; Dews, L.; Hawkins, M.; Cowie, C.; Fradkin, J.; Siebert, C.; Eastman, R.; Danis, R.; Gangaputra, S.; Neill, S.; Davis, M.; Hubbard, L.; Wabers, H.; Burger, M.; Dingledine, J.; Gama, V.; Sussman, R.; Steffes, M.; Bucksa, J.; Nowicki, M.; Chavers, B.; O’Leary, D.; Polak, J.; Harrington, A.; Funk, L.; Crow, R.; Gloeb, B.; Thomas, S.; O’Donnell, C.; Soliman, E.; Zhang, Z.M.; Prineas, R.; Campbell, C.; Ryan, C.; Sandstrom, D.; Williams, T.; Geckle, M.; Cupelli, E.; Thoma, F.; Burzuk, B.; Woodfill, T.; Low, P.; Sommer, C.; Nickander, K.; Budoff, M.; Detrano, R.; Wong, N.; Fox, M.; Kim, L.; Oudiz, R.; Weir, G.; Espeland, M.; Manolio, T.; Rand, L.; Singer, D.; Stern, M.; Boulton, A.E.; Clark, C.; D’Agostino, R.; Lopes-Virella, M.; Garvey, W.T.; Lyons, T.J.; Jenkins, A.; Virella, G.; Jaffa, A.; Carter, Rickey; Lackland, D.; Brabham, M.; McGee, D.; Zheng, D.; Mayfield, R.K.; Boright, A.; Bull, S.; Sun, L.; Scherer, S.; Zinman, B.; Natarajan, R.; Miao, F.; Zhang, L.; Chen;, Z.; Nathan, D.M.; Makela, Kari-Matti; Lehtimaki, Terho; Kahonen, Mika; Raitakari, Olli; Yoshimura, Nagahisa; Matsuda, Fumihiko; Chen, Li Jia; Pang, Chi Pui; Yip, Shea Ping; Yap, Maurice K.H.; Meguro, Akira; Mizuki, Nobuhisa; Inoko, Hidetoshi; Foster, Paul J.; Zhao, Jing Hua; Vithana, Eranga; Tai, E-Shyong; Fan, Qiao; Xu, Liang; Campbell, Harry; Fleck, Brian; Rudan, Igor; Aung, Tin; Hofman, Albert; Uitterlinden, André G.; Bencic, Goran; Khor, Chiea-Chuen; Forward, Hannah; Pärssinen, Olavi; Mitchell, Paul; Rivadeneira, Fernando; Hewitt, Alex W.; Williams, Cathy; Oostra, Ben A.; Teo, Yik-Ying; Hammond, Christopher J.; Stambolian, Dwight; Mackey, David A.; Klaver, Caroline C.W.; Wong, Tien-Yin; Saw, Seang-Mei; Baird, Paul N.

2013-01-01

Refractive errors are common eye disorders of public health importance worldwide. Ocular axial length (AL) is the major determinant of refraction and thus of myopia and hyperopia. We conducted a meta-analysis of genome-wide association studies for AL, combining 12,531 Europeans and 8,216 Asians. We identified eight genome-wide significant loci for AL (RSPO1, C3orf26, LAMA2, GJD2, ZNRF3, CD55, MIP, and ALPPL2) and confirmed one previously reported AL locus (ZC3H11B). Of the nine loci, five (LAMA2, GJD2, CD55, ALPPL2, and ZC3H11B) were associated with refraction in 18 independent cohorts (n = 23,591). Differential gene expression was observed for these loci in minus-lens-induced myopia mouse experiments and human ocular tissues. Two of the AL genes, RSPO1 and ZNRF3, are involved in Wnt signaling, a pathway playing a major role in the regulation of eyeball size. This study provides evidence of shared genes between AL and refraction, but importantly also suggests that these traits may have unique pathways. PMID:24144296

Significant Enhancement of the Chiral Correlation Length in Nematic Liquid Crystals by Gold Nanoparticle Surfaces Featuring Axially Chiral Binaphthyl Ligands.

PubMed

Mori, Taizo; Sharma, Anshul; Hegmann, Torsten

2016-01-26

surface is diminished as the size of the particle is reduced. However, in comparison to the free ligands, per chiral molecule all tested gold nanoparticles induce helical distortions in a 10- to 50-fold larger number of liquid crystal host molecules surrounding each particle, indicating a significantly enhanced chiral correlation length. We propose that both the helicity and the chirality transfer efficiency of axially chiral binaphthyl derivatives can be controlled at metal nanoparticle surfaces by adjusting the particle size and curvature as well as the number and density of the chiral ligands to ultimately measure and tune the chiral correlation length.

Telomere length analysis.

PubMed

Canela, Andrés; Klatt, Peter; Blasco, María A

2007-01-01

Most somatic cells of long-lived species undergo telomere shortening throughout life. Critically short telomeres trigger loss of cell viability in tissues, which has been related to alteration of tissue function and loss of regenerative capabilities in aging and aging-related diseases. Hence, telomere length is an important biomarker for aging and can be used in the prognosis of aging diseases. These facts highlight the importance of developing methods for telomere length determination that can be employed to evaluate telomere length during the human aging process. Telomere length quantification methods have improved greatly in accuracy and sensitivity since the development of the conventional telomeric Southern blot. Here, we describe the different methodologies recently developed for telomere length quantification, as well as their potential applications for human aging studies.

Ocular dimensions in relation to auxological data in a sample of Swedish children aged 4-15 years.

PubMed

Raffa, Lina H; Hellström, Ann; Aring, Eva; Andersson, Susann; Grönlund, Marita Andersson

2014-11-01

The purpose was to characterize normal growth patterns of ocular and optical components and to relate them to auxological data in a sample of Swedish children aged 4-15 years. A prospective cross-sectional study was carried out in 143 Swedish children with a mean age of 9.8 years. Variables including gestational age (GA), weight, length and head circumference (HCF) at birth and at the time of assessment were registered. Visual acuity (VA), cycloplegic refraction and biometric measures were obtained. Palpebral fissure length and inner canthal distance were measured. Optic disc morphology as seen on fundus photographs was analysed. Children born more mature, with male predilection, were found to have deeper anterior and vitreous chamber depths, longer axial lengths and thinner crystalline lens thickness. No correlations were found between ocular biometric measurements and VA or refraction after adjustment for confounding variables. Inner canthal distance was significantly correlated with birth length (p = 0.03), height, weight, BMI and HCF (p = 0.0008, p = 0.0007, p = 0.037, and p = 0.04, respectively) at time of assessment. Total axial length was found to be significantly correlated with GA (p = 0.0226) and length at assessment in girls (p = 0.0084). Right optic disc and rim areas decreased with increasing age (p = 0.0078 and p = 0.0107, respectively); however, optic disc parameters were not dependent on any other variable. These normative values may serve as a basis for the ocular findings and their relationship to auxological data in Caucasian children aged 4-15 years, as well as for future comparison in patients with paediatric ocular pathologies. © 2014 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Changes in the axial orientation of the zygapophyseal joint in the subaxial cervical spine from childhood to middle-age, and the biomechanical implications of these changes.

PubMed

Chen, Mao-Yu; Liu, Yu-Tse; Hsu, Wen-Hsing

2017-10-01

The objective of this study was to investigate the effect of age on facet orientation (FO) of the cervical spine during development, maturation, and degeneration. Computed tomography (CT) data of the cervical spine of 131 subjects without pathology of the cervical spine were analyzed. Subjects were categorized as: pediatric (n=36, 8-16years old), young adult (n=33, 18-24years old), and middle-age (n=62, 40-59years old). Serial CT scans were reconstructed by image processing. The FO in the axial plane was measured bilaterally at each vertebral level from C3/4 to C6/7. Differences in FO were analyzed between the 3 groups. The degree of external rotation of FO significantly decreased at C3/4 and C4/5 with increasing in age, and maximum external rotation was observed at C5/6. The external rotation at C6/7 increased from pediatric to young adulthood, but decreased from young adults to middle-aged adults. The dominant external rotation was seen in C4/5 and C5/6 in the pediatric age group, C5/6 and C6/7 in young adults, and C4/5 and C5/6 in middle-aged adults. These results lead us to conclude that FO in the axial plane exhibits significant differences with age. The degree of external rotation with respect to FO at each vertebral level is comparable to changes in cervical spinal dynamics with age. Hence, FO in the axial plane is a biomechanical parameter that can be used to assess changes in the cervical spinal during maturation and degeneration. Copyright © 2017. Published by Elsevier Ltd.

Nine loci for ocular axial length identified through genome-wide association studies, including shared loci with refractive error.

PubMed

Cheng, Ching-Yu; Schache, Maria; Ikram, M Kamran; Young, Terri L; Guggenheim, Jeremy A; Vitart, Veronique; MacGregor, Stuart; Verhoeven, Virginie J M; Barathi, Veluchamy A; Liao, Jiemin; Hysi, Pirro G; Bailey-Wilson, Joan E; St Pourcain, Beate; Kemp, John P; McMahon, George; Timpson, Nicholas J; Evans, David M; Montgomery, Grant W; Mishra, Aniket; Wang, Ya Xing; Wang, Jie Jin; Rochtchina, Elena; Polasek, Ozren; Wright, Alan F; Amin, Najaf; van Leeuwen, Elisabeth M; Wilson, James F; Pennell, Craig E; van Duijn, Cornelia M; de Jong, Paulus T V M; Vingerling, Johannes R; Zhou, Xin; Chen, Peng; Li, Ruoying; Tay, Wan-Ting; Zheng, Yingfeng; Chew, Merwyn; Burdon, Kathryn P; Craig, Jamie E; Iyengar, Sudha K; Igo, Robert P; Lass, Jonathan H; Chew, Emily Y; Haller, Toomas; Mihailov, Evelin; Metspalu, Andres; Wedenoja, Juho; Simpson, Claire L; Wojciechowski, Robert; Höhn, René; Mirshahi, Alireza; Zeller, Tanja; Pfeiffer, Norbert; Lackner, Karl J; Bettecken, Thomas; Meitinger, Thomas; Oexle, Konrad; Pirastu, Mario; Portas, Laura; Nag, Abhishek; Williams, Katie M; Yonova-Doing, Ekaterina; Klein, Ronald; Klein, Barbara E; Hosseini, S Mohsen; Paterson, Andrew D; Makela, Kari-Matti; Lehtimaki, Terho; Kahonen, Mika; Raitakari, Olli; Yoshimura, Nagahisa; Matsuda, Fumihiko; Chen, Li Jia; Pang, Chi Pui; Yip, Shea Ping; Yap, Maurice K H; Meguro, Akira; Mizuki, Nobuhisa; Inoko, Hidetoshi; Foster, Paul J; Zhao, Jing Hua; Vithana, Eranga; Tai, E-Shyong; Fan, Qiao; Xu, Liang; Campbell, Harry; Fleck, Brian; Rudan, Igor; Aung, Tin; Hofman, Albert; Uitterlinden, André G; Bencic, Goran; Khor, Chiea-Chuen; Forward, Hannah; Pärssinen, Olavi; Mitchell, Paul; Rivadeneira, Fernando; Hewitt, Alex W; Williams, Cathy; Oostra, Ben A; Teo, Yik-Ying; Hammond, Christopher J; Stambolian, Dwight; Mackey, David A; Klaver, Caroline C W; Wong, Tien-Yin; Saw, Seang-Mei; Baird, Paul N

2013-08-08

Refractive errors are common eye disorders of public health importance worldwide. Ocular axial length (AL) is the major determinant of refraction and thus of myopia and hyperopia. We conducted a meta-analysis of genome-wide association studies for AL, combining 12,531 Europeans and 8,216 Asians. We identified eight genome-wide significant loci for AL (RSPO1, C3orf26, LAMA2, GJD2, ZNRF3, CD55, MIP, and ALPPL2) and confirmed one previously reported AL locus (ZC3H11B). Of the nine loci, five (LAMA2, GJD2, CD55, ALPPL2, and ZC3H11B) were associated with refraction in 18 independent cohorts (n = 23,591). Differential gene expression was observed for these loci in minus-lens-induced myopia mouse experiments and human ocular tissues. Two of the AL genes, RSPO1 and ZNRF3, are involved in Wnt signaling, a pathway playing a major role in the regulation of eyeball size. This study provides evidence of shared genes between AL and refraction, but importantly also suggests that these traits may have unique pathways. Copyright © 2013 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.

Thermal Aging Behavior of Axial Suspension Plasma-Sprayed Yttria-Stabilized Zirconia (YSZ) Thermal Barrier Coatings

NASA Astrophysics Data System (ADS)

Zhao, Yuexing; Wang, Liang; Yang, Jiasheng; Li, Dachuan; Zhong, Xinghua; Zhao, Huayu; Shao, Fang; Tao, Shunyan

2015-02-01

7.5YSZ thermal barrier coatings (TBCs) were deposited onto the stainless steel substrates using axial suspension plasma spraying (ASPS). Free-standing coatings were isothermally aged in air from 1200 to 1600 °C for 24 h and at 1550 °C for 20 to 100 h, respectively. Thermal aging behavior such as phase composition, microstructure evolutions, grain growth, and mechanical properties for thermal-aged coatings were investigated. Results show that the as-sprayed metastable tetragonal (t'-ZrO2) phase decomposes into equilibrium tetragonal (t-ZrO2) and cubic (c-ZrO2) phases during high-temperature exposures. Upon further cooling, the c-ZrO2 may be retained or transform into another metastable tetragonal (t″-ZrO2) phase, and tetragonal → monoclinic phase transformation occurred after 1550 °C/40 h aging treatment. The coating exhibits a unique structure with segmentation cracks and micro/nano-size grains, and the grains grow gradually with increasing aging temperature and time. In addition, the hardness ( H) and Young's modulus ( E) significantly increased as a function of temperature due to healing of pores or cracks and grain growth of the coating. And a nonmonotonic variation is found in the coatings thermal aged at a constant temperature (1550 °C) with prolonged time, this is a synergetic effect of coating sintering and m-ZrO2 phase formation.

Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes

PubMed Central

2013-01-01

Background Equine incisors are subjected to continuous occlusal wear causing multiple, age related changes of the extragingival crown. It is assumed that the occlusal wear is compensated by continued tooth elongation at the apical ends of the teeth. In this study, μCT-datasets offered the opportunity to analyze the three-dimensional appearance of the extra- and intraalveolar parts of the enamel containing dental crown as well as of the enamel-free dental root. Multiple morphometric measurements elucidated age related, morphological changes within the intraalveolar part of the incisors. Results Equine incisors possess a unique enamel cover displaying large indentations on the mesial and distal sides. After eruption tooth elongation at the apical end outbalances occlusal wear for two to four years resulting in increasing incisor length in this period of time. Remarkably, this maximum length is maintained for about ten years, up to a tooth age of 13 to 15 years post eruption. Variances in the total length of individual teeth are related to different Triadan positions (central-, middle- and corner incisors) as well as to the upper and lower arcades. Conclusion Equine incisors are able to fully compensate occlusal wear for a limited period of time. However, after this ability ceases, it is expected that a diminished intraalveolar tooth length will cause massive changes in periodontal biomechanics. The time point of these morphodynamic and biomechanical changes (13 to 15 years post eruption) occurs in coincidence with the onset of a recently described destructive disease of equine incisor (equine odontoclastic tooth resorption and hypercementosis) in aged horses. However, further biomechanical, cell biological and microbiological investigations are needed to elucidate a correlation between age related changes of incisor morphology and this disease. PMID:24321365

Three-dimensional anatomy of equine incisors: tooth length, enamel cover and age related changes.

PubMed

Schrock, Patricia; Lüpke, Matthias; Seifert, Hermann; Staszyk, Carsten

2013-12-09

Equine incisors are subjected to continuous occlusal wear causing multiple, age related changes of the extragingival crown. It is assumed that the occlusal wear is compensated by continued tooth elongation at the apical ends of the teeth. In this study, μCT-datasets offered the opportunity to analyze the three-dimensional appearance of the extra- and intraalveolar parts of the enamel containing dental crown as well as of the enamel-free dental root. Multiple morphometric measurements elucidated age related, morphological changes within the intraalveolar part of the incisors. Equine incisors possess a unique enamel cover displaying large indentations on the mesial and distal sides. After eruption tooth elongation at the apical end outbalances occlusal wear for two to four years resulting in increasing incisor length in this period of time. Remarkably, this maximum length is maintained for about ten years, up to a tooth age of 13 to 15 years post eruption. Variances in the total length of individual teeth are related to different Triadan positions (central-, middle- and corner incisors) as well as to the upper and lower arcades. Equine incisors are able to fully compensate occlusal wear for a limited period of time. However, after this ability ceases, it is expected that a diminished intraalveolar tooth length will cause massive changes in periodontal biomechanics. The time point of these morphodynamic and biomechanical changes (13 to 15 years post eruption) occurs in coincidence with the onset of a recently described destructive disease of equine incisor (equine odontoclastic tooth resorption and hypercementosis) in aged horses. However, further biomechanical, cell biological and microbiological investigations are needed to elucidate a correlation between age related changes of incisor morphology and this disease.

Axial strain insensitivity of weakly guiding optical fibers

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1993-01-01

A numerical model has been developed to calculate the modal phase shift of circular step index profile weakly guiding fibers under axial strain. Whenever an optical fiber is under stress, the optical path length, the index of refraction, and the propagation constants of each mode change. In consequence, the phase of each mode is also modified. A relationship for the modal phase shift is presented. This relation is applied to both single mode and two-mode fibers in order to determine the sensitivity characteristics of strained fibers. It was found that the phase shift is strongly dependent on the core refractive index, n(co). It was also found that it is possible to design fibers which are insensitive to axial strain. Practical applications of strain insensitive fibers are discussed.

A Comparative Study to Assess the Predictability of Different IOL Power Calculation Formulas in Eyes of Short and Long Axial Length

PubMed Central

Limdi, Purvi; Parekh, Nilesh; Gohil, Neepa

2017-01-01

Introduction Accurate Intraocular Lens (IOL) power calculation in cataract surgery is very important for providing postoperative precise vision. Selection of most appropriate formula is difficult in high myopic and hypermetropic patients. Aim To investigate the predictability of different IOL (Intra Ocular Lens) power calculation formulae in eyes with short and long Axial Length (AL) and to find out most accurate IOL power calculation formula in both groups. Materials and Methods A prospective study was conducted on 80 consecutive patients who underwent phacoemulsification with monofocal IOL implantation after obtaining an informed and written consent. Preoperative keratometry was done by IOL Master. Axial length and anterior chamber depth was measured using A-scan machine ECHORULE 2 (BIOMEDIX). Patients were divided into two groups based on AL. (40 in each group). Group A with AL<22 mm and Group B with AL>24.5 mm. The IOL power calculation in each group was done by Haigis, Hoffer Q, Holladay-I, SRK/T formulae using the software of ECHORULE 2. The actual postoperative Spherical Equivalent (SE), Estimation error (E) and Absolute Error (AE) were calculated at one and half months and were used in data analysis. The predictive accuracy of each formula in each group was analyzed by comparing the Absolute Error (AE). The Kruskal Wallis test was used to compare differences in the (AE) of the formulae. A statistically significant difference was defined as p-value<0.05. Results In Group A, Hoffer Q, Holladay 1 and SRK/T formulae were equally accurate in predicting the postoperative refraction after cataract surgery (IOL power calculation) in eyes with AL less than 22.0 mm and accuracy of these three formulae was significantly higher than Haigis formula. Whereas in Group B, Hoffer Q, Holladay 1, SRK/T and Haigis formulae were equally accurate in predicting the postoperative refraction after cataract surgery (IOL power calculation) in eyes with AL more than 24.5 mm

Effects of Aging on Arm Swing during Gait: The Role of Gait Speed and Dual Tasking.

PubMed

Mirelman, Anat; Bernad-Elazari, Hagar; Nobel, Tomer; Thaler, Avner; Peruzzi, Agnese; Plotnik, Meir; Giladi, Nir; Hausdorff, Jeffrey M

2015-01-01

Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty healthy adults between the ages of 30-77 were included in this study designed to address this gap. Lightweight body fixed sensors were placed on each wrist and lower back. Participants walked under 3 walking conditions each of 1 minute: 1) comfortable speed, 2) walking while serially subtracting 3's (Dual Task), 3) walking at fast speed. Aging effects on arm swing amplitude, range, symmetry, jerk and axial rotation amplitude and jerk were compared between decades of age (30-40; 41-50; 51-60; 61-77 years). As expected, older adults walked slower (p = 0.03) and with increased stride variability (p = 0.02). Arm swing amplitude decreased with age under all conditions (p = 0.04). In the oldest group, arm swing decreased during dual task and increased during the fast walking condition (p<0.0001). Similarly, arm swing asymmetry increased during the dual task in the older groups (p<0.004), but not in the younger groups (p = 0.67). Significant differences between groups and within conditions were observed in arm swing jerk (p<0.02), axial rotation amplitude (p<0.02) and axial jerk (p<0.001). Gait speed, arm swing amplitude of the dominant arm, arm swing asymmetry and axial rotation jerk were all independent predictors of age in a multivariate model. These findings suggest that the effects of gait speed and dual tasking on arm swing and axial rotation during walking are altered among healthy older adults. Follow-up work is needed to examine if these effects contribute to reduced stability in aging.

Effects of Aging on Arm Swing during Gait: The Role of Gait Speed and Dual Tasking

PubMed Central

Mirelman, Anat; Bernad-Elazari, Hagar; Nobel, Tomer; Thaler, Avner; Peruzzi, Agnese; Plotnik, Meir; Giladi, Nir; Hausdorff, Jeffrey M.

2015-01-01

Healthy walking is characterized by pronounced arm swing and axial rotation. Aging effects on gait speed, stride length and stride time variability have been previously reported, however, less is known about aging effects on arm swing and axial rotation and their relationship to age-associated gait changes during usual walking and during more challenging conditions like dual tasking. Sixty healthy adults between the ages of 30–77 were included in this study designed to address this gap. Lightweight body fixed sensors were placed on each wrist and lower back. Participants walked under 3 walking conditions each of 1 minute: 1) comfortable speed, 2) walking while serially subtracting 3’s (Dual Task), 3) walking at fast speed. Aging effects on arm swing amplitude, range, symmetry, jerk and axial rotation amplitude and jerk were compared between decades of age (30–40; 41–50; 51–60; 61–77 years). As expected, older adults walked slower (p = 0.03) and with increased stride variability (p = 0.02). Arm swing amplitude decreased with age under all conditions (p = 0.04). In the oldest group, arm swing decreased during dual task and increased during the fast walking condition (p<0.0001). Similarly, arm swing asymmetry increased during the dual task in the older groups (p<0.004), but not in the younger groups (p = 0.67). Significant differences between groups and within conditions were observed in arm swing jerk (p<0.02), axial rotation amplitude (p<0.02) and axial jerk (p<0.001). Gait speed, arm swing amplitude of the dominant arm, arm swing asymmetry and axial rotation jerk were all independent predictors of age in a multivariate model. These findings suggest that the effects of gait speed and dual tasking on arm swing and axial rotation during walking are altered among healthy older adults. Follow-up work is needed to examine if these effects contribute to reduced stability in aging. PMID:26305896

Axial pain after posterior cervical spine surgery: a systematic review.

PubMed

Wang, Shan-Jin; Jiang, Sheng-Dan; Jiang, Lei-Sheng; Dai, Li-Yang

2011-02-01

Posterior operative approach has been the standard treatment for cervical compressive myelopathy, and axial pain after laminoplasty or laminectomy as a postoperative complication is now gradually receiving more and more attention. The objective of this study was to provide a systematic review of the current understanding of axial pain after cervical laminoplasty and laminectomy, and summarize clinical features, influence factors and preventive measures of axial pain after posterior decompressive surgery based on a review of literature published in the English language. Axial pain distributes over nuchal, periscapular and shoulder regions. Posterior surgery is not the major cause of axial pain, but axial pain can be worsened by the procedure. There are many clinical factors that influence postoperative axial pain such as age, preoperative axial pain, different surgical technique and postoperative management, but most of them are still controversial. Several surgical modifications have been innovated to reduce axial pain. Less invasive surgery, reconstruction of the extensor musculature, avoiding detachment of the semispinalis cervicis muscle and early removal of external immobilization have proved to be effective. Axial pain is under the influence of multiple factors, so comprehensive methods are required to reduce and avoid the postoperative axial pain. Because of methodological shortcomings in publications included in this systematic review, different results from different studies may be produced due to differences in study design, evaluation criteria, sample size, and incidence or severity of axial pain. More high-quality studies are necessary for drawing more reliable and convincing conclusions.

Characteristics of the Swirling Flow Generated by an Axial Swirler

NASA Technical Reports Server (NTRS)

Fu, Yongqiang; Jeng, San-Mou; Tacina, Robert

2005-01-01

An experimental investigation was conducted to study the aerodynamic characteristics of the confined, non-reacting, swirling flow field. The flow was generated by a helicoidal axial-vaned swirler with a short internal convergent-divergent venturi, which was confined within 2-inch square test section. A series of helicoidal axial-vaned swirlers have been designed with tip vane angles of 40 deg., 45 deg., 50 deg., 55 deg., 60 deg. and 65 deg.. The swirler with the tip vane angle of 60 deg. was combined with several simulated fuel nozzle insertions of varying lengths. A two-component Laser Doppler Velocimetry (LDV) system was employed to measure the three-component mean velocities and Reynolds stresses. Detailed data are provided to enhance understanding swirling flow with different swirl degrees and geometries and to support the development of more accurate physicaVnumerica1 models. The data indicated that the degree of swirl had a clear impact on the mean and turbulent flow fields. The swirling flow fields changed significantly with the addition of a variety of simulated fuel nozzle insertion lengths

Stress appraisals and cellular aging: A key role for anticipatory threat in the relationship between psychological stress and telomere length

PubMed Central

O’Donovan, Aoife; Tomiyama, A. Janet; Lin, Jue; Puterman, Eli; Adler, Nancy E.; Kemeny, Margaret; Wolkowitz, Owen M.; Blackburn, Elizabeth H.; Epel, Elissa S.

2012-01-01

Chronic psychological stressis a risk factor formultiple diseases of aging. Accelerated cellular aging as indexed by short telomere length has emerged as a potential common biological mechanism linking various forms of psychological stress and diseases of aging. Stress appraisals determine the degree and type of biological stress responses and altered stress appraisals may be a common psychological mechanism linking psychological stress and diseases of aging. However, no previous studies have examined the relationship between stress appraisals and telomere length. We exposed chronically stressed female caregivers and non-caregiving controls (N= 50; M age = 62.14±6.10) to a standardized acute laboratory stressor and measured their anticipatory and retrospective threat and challenge appraisals of the stressor. We hypothesized that threat and challenge appraisals would be associated with shorter and longer telomere length respectively, and that chronic care giving stress would influence telomere length through altered stress appraisals. Higher anticipatory threat appraisals were associated with shorter age-adjusted telomere length (β = −.32, p = .03), but challenge appraisals and retrospective threat appraisals showed no independent association with telomere length. Caregivers reported significantly higher anticipatory (β = −.36, p = .006)and retrospective (β = −.29, p = .03) threat appraisals than controls, but similar challenge appraisals. Although there was no significant main effect of caregiver status on telomere length, care giving had a significant indirect effect on telomere length through anticipatory threat appraisals. Exaggerated anticipatory threat appraisals may be a common and modifiable psychological mechanism of psychological stress effects on cellular aging. PMID:22293459

Axial-Force Reduction by Interference Between Jet and Neighboring Afterbody

NASA Technical Reports Server (NTRS)

Pitts, William C.; Wiggins, Lyle E.

1960-01-01

Experimental results are presented for an exploratory investigation of the effectiveness of interference between jet and afterbody in reducing the axial force on an afterbody with a neighboring jet. In addition to the interference axial force., measurements are presented of the interference normal force and the center of pressure of the interference normal force. The free-stream Mach number was 2.94, the jet-exit Mach number was 2.71, and the Reynolds number was 0.25 x 10, based on body diameter. The variables investigated include static-pressure ratio of the jet (up to 9), nacelle position relative to afterbody, angle of attack (-5 deg to 10 deg), and afterbody shape. Two families of afterbody shapes were tested. One family consisted of tangent-ogive bodies of revolution with varying length and base areas. The other family was formed by taking a planar slice off a circular cylinder with varying angle between the plane and cylinder. The trends with these variables are shown for conditions near maximum jet-afterbody interference. The interference axial forces are large and favorable. For several configurations the total afterbody axial force is reduced to zero by the interference.

Analysis of Mechanical Failure of Polymer Microneedles by Axial Force

PubMed Central

Park, Jung-Hwan; Prausnitz, Mark R.

2010-01-01

A polymeric microneedle has been developed for drug delivery applications. The ultimate goal of the polymeric microneedle is insertion into the specified region without failure for effective transdermal drug delivery. Mechanical failure of various geometries of microneedles by axial load was modeled using the Euler formula and the Johnson formula to predict the failure force of tapered-column microneedles. These formulas were compared with measured data to identify the mechanical behavior of microneedles by determining the critical factors including the actual length and end-fixed factor. The comparison of the two formulas with the data showed good agreement at the end-fixity (K) of 0.7. This value means that a microneedle column has one fixed end and one pinned end, and that part of the microneedle was overloaded by axial load. When the aspect ratio of length to equivalent diameter is 12:1 at 3 GPa of Young’s modulus, there is a transition from the Euler region to the Johnson region by the decreased length and increased base diameter of the microneedle. A polymer having less than 3 GPa of stiffness would follow the Euler formula. A 12:1 aspect ratio of length to equivalent diameter of the microneedle was the mechanical indicator determining the failure mode between elastic buckling and inelastic buckling at less than 3 GPa of Young’s modulus of polymer. Microneedles with below a 12:1 aspect ratio of length-to-equivalent diameter and more than 3 GPa of Young’s were recommended for reducing sudden failure by buckling and for successfully inserting the microneedle into the skin. PMID:21218133

Maximum length and age of round gobies (Apollonia melanostomus) in Lake Huron

USGS Publications Warehouse

French, John R. P.; Black, M. Glen

2009-01-01

The round goby (Apollonia [Neogobius] melanostomus,) an invasive species, is generally smaller and shorter-lived in the Great Lakes than it native range. We examined 30 large male round gobies from trawl samples taken in Lake Huron and used otoliths to determine their age and back-calculated growth. Standard lengths ranged from 76 to 97 mm, and the oldest fish were age-5. Low water temperatures in nearshore regions of Lake Huron might cause slow growth and late maturation.

Axial spondyloarthritis.

PubMed

Sieper, Joachim; Braun, Jürgen; Dougados, Maxime; Baeten, Dominique

2015-07-09

The term axial spondyloarthritis covers both non-radiographic disease and radiographic disease (also known as ankylosing spondylitis). Some studies have been performed to investigate the prevalence of axial spondyloarthritis, although most are limited to patients with radiographic disease. A strong genetic association has been shown between axial spondyloarthritis and human leukocyte antigen-B27 (HLA-B27), but the pathogenetic role of HLA-B27 has not yet been clarified. Tumour necrosis factor (TNF), IL-17, IL-23 and downstream pathways also seem to be important - based on the good results of therapies directed against these molecules - but their exact role in the inflammatory process is also not yet clear. Elucidating the interaction between osteoproliferation and inflammation will be crucial for the prevention of long-term structural damage of the bone. The development of new criteria for classification, diagnosis and screening of patients with axial spondyloarthritis will enable earlier intervention for this chronic inflammatory disease. MRI has become an important tool for the early detection of axial spondyloarthritis. NSAIDs and TNF blockers are effective therapies, including in the early non-radiographic stage. Therapeutic blockade of IL-17 or IL-23 seems to be a promising new treatment option. Tools for measuring quality of life in axial spondyloarthritis have become relevant to assess the impact that the disease has on patients. These diagnostic and therapeutic advances will continue to change the management of axial spondyloarthritis, and new insights into the disease pathogenesis will hopefully accelerate this process. For an illustrated summary of this Primer, visit: http://go.nature.com/51b1af.

Axial and Radial Permeability Evolutions of Compressed Sandstones: End Effects and Shear-band Induced Permeability Anisotropy

NASA Astrophysics Data System (ADS)

Dautriat, Jeremie; Gland, Nicolas; Guelard, Jean; Dimanov, Alexandre; Raphanel, Jean L.

2009-07-01

The influence of hydrostatic and uniaxial stress states on the porosity and permeability of sandstones has been investigated. The experimental procedure uses a special triaxial cell which allows permeability measurements in the axial and radial directions. The core sleeve is equipped with two pressure samplers placed distant from the ends. They provide mid-length axial permeability measure as opposed to the overall permeability measure, which is based on the flow imposed through the pistons of the triaxial cell. The core sleeve is also equipped to perform flows in two directions transverse to the axis of the sample. Two independent measures of axial and complementary radial permeability are thus obtained. Both Fontainebleau sandstone specimens with a porosity of about 5.8% to 8% and low permeability ranging from 2.5 mD to 30 mD and Bentheimer sandstone with a porosity of 24% and a high permeability of 3 D have been tested. The initial axial permeability values obtained by each method are in good agreement for the Fontainebleau sandstone. The Bentheimer sandstone samples present an axial mid-length permeability 1.6 times higher than the overall permeability. A similar discrepancy is also observed in the radial direction, also it relates essentially to the shape of flow lines induced by the radial flow. All the tested samples have shown a higher stress dependency of overall and radial permeability than mid-length permeability. The effect of compaction damage at the pistons/sample and radial ports/sample interfaces is discussed. The relevance of directional permeability measurements during continuous uniaxial compression loadings has been shown on the Bentheimer sandstone until the failure of the sample. We can efficiently measure the influence of brittle failure associated to dilatant regime on the permeability: It tends to increase in the failure propagation direction and to decrease strongly in the transverse direction.

Refractive indices used by the Haag-Streit Lenstar to calculate axial biometric dimensions.

PubMed

Suheimat, Marwan; Verkicharla, Pavan K; Mallen, Edward A H; Rozema, Jos J; Atchison, David A

2015-01-01

To estimate refractive indices used by the Lenstar biometer to translate measured optical path lengths into geometrical path lengths within the eye. Axial lengths of model eyes were determined using the IOLMaster and Lenstar biometers; comparing those lengths gave an overall eye refractive index estimate for the Lenstar. Using the Lenstar Graphical User Interface, we noticed that boundaries between media could be manipulated and opposite changes in optical path lengths on either side of the boundary could be introduced. Those ratios were combined with the overall eye refractive index to estimate separate refractive indices. Furthermore, Haag-Streit provided us with a template to obtain 'air thicknesses' to compare with geometrical distances. The axial length estimates obtained using the IOLMaster and the Lenstar agreed to within 0.01 mm. Estimates of group refractive indices used in the Lenstar were 1.340, 1.341, 1.415, and 1.354 for cornea, aqueous, lens, and overall eye, respectively. Those refractive indices did not match those of schematic eyes, but were close in the cases of aqueous and lens. Linear equations relating air thicknesses to geometrical thicknesses were consistent with our findings. The Lenstar uses different refractive indices for different ocular media. Some of the refractive indices, such as that for the cornea, are not physiological; therefore, it is likely that the calibrations in the instrument correspond to instrument-specific corrections and are not the real optical path lengths. © 2014 The Authors Ophthalmic & Physiological Optics © 2014 The College of Optometrists.

Variable focal length deformable mirror

DOEpatents

Headley, Daniel [Albuquerque, NM; Ramsey, Marc [Albuquerque, NM; Schwarz, Jens [Albuquerque, NM

2007-06-12

A variable focal length deformable mirror has an inner ring and an outer ring that simply support and push axially on opposite sides of a mirror plate. The resulting variable clamping force deforms the mirror plate to provide a parabolic mirror shape. The rings are parallel planar sections of a single paraboloid and can provide an on-axis focus, if the rings are circular, or an off-axis focus, if the rings are elliptical. The focal length of the deformable mirror can be varied by changing the variable clamping force. The deformable mirror can generally be used in any application requiring the focusing or defocusing of light, including with both coherent and incoherent light sources.

Model of an axially strained weakly guiding optical fiber modal pattern

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1992-01-01

Axial strain can be determined by monitoring the modal pattern variation of an optical fiber. The results of a numerical model developed to calculate the modal pattern variation at the end of a weakly guiding optical fiber under axial strain is presented. Whenever an optical fiber is under stress, the optical path length, the index of refraction, and the propagation constants of each fiber mode change. In consequence, the modal phase term for the fields and the fiber output pattern are also modified. For multimode fibers, very complicated patterns result. The predicted patterns are presented, and an expression for the phase variation with strain is derived.

Axial Seamount Relative Eruption Timing Constraints Based on Paleointensity Data

NASA Astrophysics Data System (ADS)

Bowles, J. A.; Dreyer, B. M.; Clague, D. A.

2013-12-01

Axial Seamount, located on the Juan de Fuca Ridge in the northeast Pacific, is one of the most extensively studied seamounts in the world. High-resolution mapping and camera imagery by remotely operated vehicle (ROV) have allowed for the creation of a geologic map of the caldera. Individual flow fields have been identified, and relative ages have been assigned based on ROV observations. Some constraints on absolute age have been obtained by 14C dating of the overlying sediments, and flows with inadequate sediment to sample are assumed to be less than 300 years old. To refine relative age relationships between flow fields, geomagnetic paleointensity recorded in basaltic glass is compared with models of field behavior over the past ~1,000 years. Thellier-type paleointensity experiments were carried out on samples from within Axial caldera. Paleointensity results from the 2011 Axial eruption give a paleofield value of 46.0×4.5 μT compared to the IGRF value of 52.1 μT. This suggests that the geodynamo-produced field is being locally distorted by the pre-existing magnetic topography of Axial seamount. Long-wavelength distortion may arise from the large seamount edifice itself, or short- wavelength distortion may arise from small scale (meters to 10s of meters) roughness in the surface flows. The dominance of long-wavelength distortion is implied by an analysis of samples from other flows within the Axial caldera. Within each flow, the paleointensity values are relatively tightly clustered compared to the overall scatter in the data, suggesting that short-wavelength distortion is minimized. These flows are thought to be less than a few hundred years old, and over this time period, the strength of the geomagnetic field should be monotonically decreasing. Such a decreasing trend is recovered in paleointensity results from flows in the north, south, and east caldera regions, supporting the relative age interpretations made from ROV observations. However, all

Usefulness of oblique axial scan in magnetic resonance imaging evaluation of anterior talofibular ligament in ankle sprain.

PubMed

Kim, Jin-su; Moon, Yong-ju; Choi, Yun Sun; Park, Young Uk; Park, Seung Min; Lee, Kyung Tai

2012-01-01

The purpose of the present study was to clarify the usefulness of the oblique axial scan parallel to the course of the anterior talofibular ligament in magnetic resonance imaging of the anterior talofibular ligament in patients with chronic ankle instability. We evaluated this anterior talofibular ligament view and routine axial magnetic resonance imaging planes of 115 ankles. We diagnosed the grade of the anterior talofibular ligament injury and confirmed full-length views of the anterior talofibular ligament. Associated lesions were also checked. The subjective diagnostic convenience of associated problems was determined. The full-length view of the anterior talofibular ligament was checked in 85 (73.9%) patients in the routine axial view and 112 (97.4%) patients in the anterior talofibular ligament view. The grade of injury increased in the anterior talofibular ligament view in 26 (22.6%) patients compared with the routine axial view. There were 64 associated injuries. The anterior inferior tibiofibular ligament, posterior inferior tibiofibular ligament, and posterior tibialis tendinitis were more easily diagnosed on the routine axial view than on the anterior talofibular ligament view. An additional anterior talofibular ligament view is useful in the evaluation of the anterior talofibular ligament in patients with chronic ankle instability. Copyright © 2012 American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.

Prevalence and Length of the Anterior Loop of the Inferior Alveolar Nerve in Iranians.

PubMed

Moghddam, Maryam Rastegar; Davoudmanesh, Zeinab; Azizi, Nasim; Rakhshan, Vahid; Shariati, Mahsa

2017-10-01

The anterior loop of the inferior alveolar nerve is a sensitive anatomical feature that should be taken into account during installation of dental implants anterior to the mental foramen. This study was conducted to explore the controversy regarding prevalence and length. A total of 452 mandible quadrants of 234 patients (age: 50.1 ± 13.3 years, 113 males, 121 females) were studied using cone-beam computerized tomography. After reconstructing axial, frontal, and sagittal slices, the region between the most anterior point on the mental foramen and the most anterior part of the mandibular nerve was inspected for signs of anterior loop presence. If positive, the length of the anterior loop was measured in mm as the distance between the anterior border of mental foramen and the anterior border of the loop. Prevalence and length of the anterior loop were compared statistically between sexes and age groups. The anterior loop was observed in 106 quadrants (23.5% of 451 quadrants) of 95 patients (40.6% of 234 patients), of whom 11 had bilateral anterior loops. Prevalences were similar in males (41%) and females (39%, chi-square P =.791). The mean anterior loop length was 2.77 ± 1.56 mm (95% CI: 2.5-3.1 mm), without significant sex (regression beta = -0.159, P = .134) or age (beta = -0.059, P = .578) differences. The anterior loop might exist in about 40% of patients, regardless of their gender. The mean safe anterior distance from the anterior loop is about 3 mm + (2.5-3.1 mm) = 5.5-6.1 mm, regardless of age.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body.

PubMed

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification.

Normal axial alignment of the lower extremity and load-bearing distribution at the knee.

PubMed

Hsu, R W; Himeno, S; Coventry, M B; Chao, E Y

1990-06-01

Based on a series of 120 normal subjects of different gender and age, the geometry of the knee joint was analyzed using a full-length weight-bearing roentgenogram of the lower extremity. A special computer program based on the theory of a rigid body spring model was applied to calculate the important anatomic and biomechanical factors of the knee joint. The tibiofemoral mechanical angle was 1.2 degrees varus. Hence, it is difficult to rationalize the 3 degree varus placement of the tibial component in total knee arthroplasty suggested by some authors. The distal femoral anatomic valgus (measured from the lower one-half of the femur) was 4.2 degrees in reference to its mechanical axis. This angle became 4.9 degrees when the full-length femoral anatomic axis was used. When simulating a one-legged weight-bearing stance by shifting the upper-body gravity closer to the knee joint, 75% of the knee joint load passed through the medial tibial plateau. The knee joint-line obliquity was more varus in male subjects. The female subjects had a higher peak joint pressure and a greater patello-tibial Q angle. Age had little effect on the factors relating to axial alignment of the lower extremity and load transmission through the knee joint.

Distribution of the Crystalline Lens Power In Vivo as a Function of Age.

PubMed

Jongenelen, Sien; Rozema, Jos J; Tassignon, Marie-José

2015-11-01

To observe the age-related changes in crystalline lens power in vivo in a noncataractous European population. Data were obtained though Project Gullstrand, a multicenter population study with data from healthy phakic subjects between 20 and 85 years old. One randomly selected eye per subject was used. Lens power was calculated using the modified Bennett-Rabbetts method, using biometry data from an autorefractometer, Oculus Pentacam, and Haag-Streit Lenstar. The study included 1069 Caucasian subjects (490 men, 579 women) with a mean age of 44.2 ± 14.2 years and mean lens power of 24.96 ± 2.18 diopters (D). The average lens power showed a statistically significant decrease as a function of age, with a steeper rate of decrease after the age of 55. The highest crystalline lens power was found in emmetropic eyes and eyes with a short axial length. The correlation of lens power with different refractive components was statistically significant for axial length (r = -0.523, P < 0.01) and anterior chamber depth (r = -0.161, P < 0.01), but not for spherical equivalent and corneal power (P > 0.05). This in vivo study showed a monotonous decrease in crystalline lens power with age, with a steeper decline after 55 years. While this finding fundamentally concurs with previous in vivo studies, it is at odds with studies performed on donor eyes that reported lens power increases after the age of 55.

Model of an axially strained weakly guiding optical fiber modal pattern

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1991-01-01

Axial strain may be determined by monitoring the modal pattern variation of an optical fiber. In this paper we present the results of a numerical model that has been developed to calculate the modal pattern variation at the end of a weakly guiding optical fiber under axial strain. Whenever an optical fiber is under stress, the optical path length, the index of refraction and the propagation constants of each fiber mode change. In consequence, the modal phase term of the fields and the fiber output pattern are also modified. For multimode fibers, very complicated patterns result. The predicted patterns are presented, and an expression for the phase variation with strain is derived.

Longitudinal changes of telomere length and epigenetic age related to traumatic stress and post-traumatic stress disorder.

PubMed

Boks, Marco P; van Mierlo, Hans C; Rutten, Bart P F; Radstake, Timothy R D J; De Witte, Lot; Geuze, Elbert; Horvath, Steve; Schalkwyk, Leonard C; Vinkers, Christiaan H; Broen, Jasper C A; Vermetten, Eric

2015-01-01

Several studies have reported an association between traumatic stress and telomere length suggesting that traumatic stress has an impact on ageing at the cellular level. A newly derived tool provides an additional means to investigate cellular ageing by estimating epigenetic age based on DNA methylation profiles. We therefore hypothesise that in a longitudinal study of traumatic stress both indicators of cellular ageing will show increased ageing. We expect that particularly in individuals that developed symptoms of post-traumatic stress disorder (PTSD) increases in these ageing parameters would stand out. From an existing longitudinal cohort study, ninety-six male soldiers were selected based on trauma exposure and the presence of symptoms of PTSD. All military personnel were deployed in a combat zone in Afghanistan and assessed before and 6 months after deployment. The Self-Rating Inventory for PTSD was used to measure the presence of PTSD symptoms, while exposure to combat trauma during deployment was measured with a 19-item deployment experiences checklist. These groups did not differ for age, gender, alcohol consumption, cigarette smoking, military rank, length, weight, or medication use. In DNA from whole blood telomere length was measured and DNA methylation levels were assessed using the Illumina 450K DNA methylation arrays. Epigenetic ageing was estimated using the DNAm age estimator procedure. The association of trauma with telomere length was in the expected direction but not significant (B=-10.2, p=0.52). However, contrary to our expectations, development of PTSD symptoms was associated with the reverse process, telomere lengthening (B=1.91, p=0.018). In concordance, trauma significantly accelerated epigenetic ageing (B=1.97, p=0.032) and similar to the findings in telomeres, development of PTSD symptoms was inversely associated with epigenetic ageing (B=-0.10, p=0.044). Blood cell count, medication and premorbid early life trauma exposure did not

Fast-axial turbulent flow CO2 laser output characteristics and scaling parameters

NASA Astrophysics Data System (ADS)

Dembovetsky, V. V.; Zavalova, Valentina Y.; Zavalov, Yuri N.

1996-04-01

The paper presents the experimental results of evaluating the output characteristics of TLA- 600 carbon-dioxide laser with axial turbulent gas flow, as well as the results of numerical modeling. The output characteristic and spatial distribution of laser beam were measured with regard to specific energy input, working mixture pressure, active media length and output mirror reflection. The paper presents the results of experimental and theoretical study and design decisions on a succession of similar type industrial carbon-dioxide lasers with fast-axial gas-flow and dc discharge excitation of active medium developed at NICTL RAN. As an illustration, characteristics of the TLA-600 laser are cited.

Evaluation of skeletal and dental age using third molar calcification, condylar height and length of the mandibular body

PubMed Central

Kedarisetty, Sunil Gupta; Rao, Guttikonda Venkateswara; Rayapudi, Naveen; Korlepara, Rajani

2015-01-01

Aim: To identify the most reliable method for age estimation among three variables, that is, condylar height, length of mandibular body and third molar calcification by Demirjian's method. Materials and Methods: Orthopantomograms and lateral cephalograms of 60 patients with equal gender ratio were included in the study, among each gender 15 subjects were below 18 years and 15 subjects were above 18 years. Lateral cephalograms were traced, height of condyle and mandibular body are measured manually on the tracing paper, OPG's were observed on radiographic illuminator and maturity score of third molar calcification was noted according to Demirjian's method. All the measurements were subjected to statistical analysis. Results: The results obtained are of no significant difference between estimated age and actual age with all three parameters (P > 0.9780 condylar height, P > 0.9515 length of mandibular body, P > 0.8611 third molar calcification). Among these three, length of mandibular body shows least standard error test (i.e. 0.188). Conclusion: Although all three parameters can be used for age estimation, length of mandibular body is more reliable followed by height of condyle and third molar calcification. PMID:26005300

Arm span and ulnar length are reliable and accurate estimates of recumbent length and height in a multiethnic population of infants and children under 6 years of age.

PubMed

Forman, Michele R; Zhu, Yeyi; Hernandez, Ladia M; Himes, John H; Dong, Yongquan; Danish, Robert K; James, Kyla E; Caulfield, Laura E; Kerver, Jean M; Arab, Lenore; Voss, Paula; Hale, Daniel E; Kanafani, Nadim; Hirschfeld, Steven

2014-09-01

Surrogate measures are needed when recumbent length or height is unobtainable or unreliable. Arm span has been used as a surrogate but is not feasible in children with shoulder or arm contractures. Ulnar length is not usually impaired by joint deformities, yet its utility as a surrogate has not been adequately studied. In this cross-sectional study, we aimed to examine the accuracy and reliability of ulnar length measured by different tools as a surrogate measure of recumbent length and height. Anthropometrics [recumbent length, height, arm span, and ulnar length by caliper (ULC), ruler (ULR), and grid (ULG)] were measured in 1479 healthy infants and children aged <6 y across 8 study centers in the United States. Multivariate mixed-effects linear regression models for recumbent length and height were developed by using ulnar length and arm span as surrogate measures. The agreement between the measured length or height and the predicted values by ULC, ULR, ULG, and arm span were examined by Bland-Altman plots. All 3 measures of ulnar length and arm span were highly correlated with length and height. The degree of precision of prediction equations for length by ULC, ULR, and ULG (R(2) = 0.95, 0.95, and 0.92, respectively) was comparable with that by arm span (R(2) = 0.97) using age, sex, and ethnicity as covariates; however, height prediction by ULC (R(2) = 0.87), ULR (R(2) = 0.85), and ULG (R(2) = 0.88) was less comparable with arm span (R(2) = 0.94). Our study demonstrates that arm span and ULC, ULR, or ULG can serve as accurate and reliable surrogate measures of recumbent length and height in healthy children; however, ULC, ULR, and ULG tend to slightly overestimate length and height in young infants and children. Further testing of ulnar length as a surrogate is warranted in physically impaired or nonambulatory children. © 2014 American Society for Nutrition.

Corneal Thickness Profile and Associations in Chinese Children Aged 7 to 15 Years Old.

PubMed

Ma, Yingyan; Zhu, Xiaofeng; He, Xiangui; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-01-01

Corneal thickness (CT) maps of the central (2-mm diameter), para-central (2 to 5-mm diameter), peripheral (5 to 6-mm diameter), and minimum (5-mm diameter) cornea were measured in normal Chinese school children aged 7 to 15 years old using Fourier-domain optical coherence tomography. Multiple regression analyses were performed to explore the effect of associated factors [age, gender, refraction, axial length and corneal curvature radius (CCR)] on CT and the relationship between central corneal thickness (CCT) and intraocular pressure (IOP). A total of 1228 eyes from 614 children were analyzed. The average CCT was 532.96 ± 28.33 μm for right eyes and 532.70 ±28.45 μm for left eyes. With a 10 μm increase in CCT, the IOP was elevated by 0.37 mm Hg, as measured by noncontact tonometry. The CT increased gradually from the center to the periphery. The superior and superior nasal regions had the thickest CTs, while the thinnest points were primarily located in the inferior temporal cornea. The CCT was associated with CCR (p = 0.008) but not with gender (p = 0.075), age (p = 0.286), axial length (p = 0.405), or refraction (p = 0.985). In the para-central region and the peripheral cornea, increased CT was associated with younger age, male gender, and a flatter cornea.

Corneal Epithelium Thickness Profile in 614 Normal Chinese Children Aged 7-15 Years Old.

PubMed

Ma, Yingyan; He, Xiangui; Zhu, Xiaofeng; Lu, Lina; Zhu, Jianfeng; Zou, Haidong

2016-03-23

The purpose of the study is to describe the values and distribution of corneal epithelium thickness (CET) in normal Chinese school-aged children, and to explore associated factors with CET. CET maps were measured by Fourier-domain optical coherence tomography (FD-OCT) in normal Chinese children aged 7 to 15 years old from two randomly selected schools in Shanghai, China. Children with normal intraocular pressure were further examined for cycloplegic autorefraction, corneal curvature radius (CCR) and axial length. Central (2-mm diameter area), para-central (2- to 5-mm diameter area), and peripheral (5- to 6-mm diameter area) CET in the superior, superotemporal, temporal, inferotemporal, inferior, inferonasal, nasal, superonasal cornea; minimum, maximum, range, and standard deviation of CET within the 5-mm diameter area were recorded. The CET was thinner in the superior than in the inferior and was thinner in the temporal than in the nasal. The maximum CET was located in the inferior zone, and the minimum CET was in the superior zone. A thicker central CET was associated with male gender (p = 0.009) and older age (p = 0.037) but not with CCR (p = 0.061), axial length (p = 0.253), or refraction (p = 0.351) in the multiple regression analyses. CCR, age, and gender were correlated with para-central and peripheral CET.

Subjectively measured ejaculation latency time and its association with different sexual activities while controlling for age and relationship length.

PubMed

Jern, Patrick; Santtila, Pekka; Johansson, Ada; Varjonen, Markus; Witting, Katarina; von der Pahlen, Bettina; Sandnabba, Kenneth

2009-09-01

Recently, attempts to formulate valid and suitable definitions for (different subcategories of) premature ejaculation have resulted in substantial progress in the pursuit to gain knowledge about ejaculatory function. However, the association between ejaculatory dysfunction and different types of sexual activities has yet to be thoroughly investigated, and (due to conflicting results between studies) the potential effects of age and relationship length still need to be taken into account. The aim of this study is to investigate the associations of age, relationship length, frequency of different sexual activities, and different modes of achieving ejaculation with self-reported ejaculation latency time. The main outcome is establishing associations between age, relationship length, self-reported ejaculation latency time, and frequency of different kinds of sexual activities and different modes of achieving ejaculation (such as achieving ejaculation through oral or vaginal sex). Statistical analyses of data on age, relationship length, self-reported ejaculation latency time, and frequency of different sexual activities and different modes of achieving ejaculation were conducted on a population-based sample of 3,189 males aged 18-48 years (mean = 29.9 years, standard deviation = 6.94). Age and relationship length were significantly negatively associated with self-reported ejaculation latency time. Frequency of different kinds of sexual behavior generally had a positive association with self-reported ejaculation latency time, as had different modes of achieving ejaculation. The findings highlight the need for more extensive studies on and increased knowledge of different aspects of ejaculatory function before a valid and suitable definition for premature ejaculation can be formulated.

The effects of age and step length on joint kinematics and kinetics of large out-and-back steps.

PubMed

Schulz, Brian W; Ashton-Miller, James A; Alexander, Neil B

2008-06-01

Maximum step length (MSL) is a clinical test that has been shown to correlate with age, various measures of fall risk, and knee and hip joint extension speed, strength, and power capacities, but little is known about the kinematics and kinetics of the large out-and-back step utilized. Body motions and ground reaction forces were recorded for 11 unimpaired younger and 10 older women while attaining maximum step length. Joint kinematics and kinetics were calculated using inverse dynamics. The effects of age group and step length on the biomechanics of these large out-and-back steps were determined. Maximum step length was 40% greater in the younger than in the older women (P<0.0001). Peak knee and hip, but not ankle, angle, velocity, moment, and power were generally greater for younger women and longer steps. After controlling for age group, step length generally explained significant additional variance in hip and torso kinematics and kinetics (incremental R2=0.09-0.37). The young reached their peak knee extension moment immediately after landing of the step out, while the old reached their peak knee extension moment just before the return step liftoff (P=0.03). Maximum step length is strongly associated with hip kinematics and kinetics. Delays in peak knee extension moment that appear to be unrelated to step length, may indicate a reduced ability of older women to rapidly apply force to the ground with the stepping leg and thus arrest the momentum of a fall.

The effects of age and step length on joint kinematics and kinetics of large out-and-back steps

PubMed Central

Schulz, Brian W.; Ashton-Miller, James A.; Alexander, Neil B.

2008-01-01

Background Maximum Step Length is a clinical test that has been shown to correlate with age, various measures of fall risk, and knee and hip joint extension speed, strength, and power capacities, but little is known about the kinematics and kinetics of the large out-and-back step utilized. Methods Body motions and ground reaction forces were recorded for 11 unimpaired younger and 10 older women while attaining Maximum Step Length. Joint kinematics and kinetics were calculated using inverse dynamics. The effects of age group and step length on the biomechanics of these large out-and-back steps were determined. Findings Maximum Step Length was 40% greater in the younger than in the older women (p<0.0001). Peak knee and hip, but not ankle, angle, velocity, moment, and power were generally greater for younger women and longer steps. After controlling for age group, step length generally explained significant additional variance in hip and torso kinematics and kinetics (incremental R2=0.09–0.37). The young reached their peak knee extension moment immediately after landing of the step out, while the old reached their peak knee extension moment just before the return step lift off (p=0.03). Interpretation Maximum Step Length is strongly associated with hip kinematics and kinetics. Delays in peak knee extension moment that appear to be unrelated to step length, may indicate a reduced ability of older women to rapidly apply force to the ground with the stepping leg and thus arrest the momentum of a fall. PMID:18308435

Depressive Symptoms and Salivary Telomere Length in a Probability Sample of Middle-Aged and Older Adults.

PubMed

Whisman, Mark A; Richardson, Emily D

To examine the association between depressive symptoms and salivary telomere length in a probability sample of middle-aged and older adults, and to evaluate age and sex as potential moderators of this association and test whether this association was incremental to potential confounds. Participants were 3,609 individuals from the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction on DNA extracted from saliva samples. Depressive symptoms were assessed via interview, and health and lifestyle factors, traumatic life events, and neuroticism were assessed via self-report. Regression analyses were conducted to examine the associations between predictor variables and salivary telomere length. After adjusting for demographics, depressive symptoms were negatively associated with salivary telomere length (b = -.003; p = .014). Furthermore, this association was moderated by sex (b = .005; p = .011), such that depressive symptoms were significantly and negatively associated with salivary telomere length for men (b = - .006; p < .001) but not for women (b = - .001; p = .644). The negative association between depressive symptoms and salivary telomere length in men remained statistically significant after additionally adjusting for cigarette smoking, body mass index, chronic health conditions, childhood and lifetime exposure to traumatic life events, and neuroticism. Higher levels of depressive symptoms were associated with shorter salivary telomeres in men, and this association was incremental to several potential confounds. Shortened telomeres may help account for the association between depression and poor physical health and mortality.

Magnetic resonance imaging mesencephalic tectum dimensions according to age and gender.

PubMed

Sabanciogullari, Vedat; Salk, Ismail; Balaban, Hatice; Oztoprak, Ibrahim; Kelkit, Seref; Cimen, Mehmet

2013-01-01

To analyze and classify normal MRI tectum length and colliculus dimensions according to age and gender. Tectum length and colliculus diameters were measured on the T1 midsagittal and axial cranial MR images in the radiology archive of 532 (344 women, 188 men) patients aged 37.36+/-21.49 (range: 4-91) years old on average, and with no disorders affecting the mesencephalic tectum. All 532 patients underwent clinical MR imaging of the cranium at the MRI Unit of Sivas Numune Hospital and Sivas Cumhuriyet University Hospital, Sivas, Turkey between February and December 2011. Although there was a positive linear correlation between tectum length and age, there was a negative correlation between the anteroposterior diameter of the colliculus superior and colliculus inferior and age (p<0.01). While tectum length (M3) increases with age, the anteroposterior diameter of the colliculus superior and inferior (M1 and M2) decreased (p<0.01). The colliculi were larger, and the tectum was longer in men. Although there was no difference in size between right and left superior colliculi, the left colliculus inferior was larger than the right one. In addition to the fact that normal mesencephalic tectum dimensions provide information on the brain development of individuals, they may also be beneficial for the detection and treatment of related pathologies.

Effect of ethnicity and sex on the growth of the axial and appendicular skeleton of children living in a developing country.

PubMed

Nyati, Lukhanyo H; Norris, Shane A; Cameron, Noel; Pettifor, John M

2006-05-01

Bones in the axial and appendicular skeletons exhibit heterogeneous growth patterns between different ethnic and sex groups. However, the influence of this differential growth on the expression of bone mineral content is not yet established. The aims of the present study were to investigate: 1) whether there are ethnic and sex differences in axial and appendicular dimensions of South African children; and 2) whether regional segment length is a better predictor of bone mass than stature. Anthropometric measurements of stature, weight, sitting height, and limb lengths were taken on 368 black and white, male and female 9-year-old children. DXA (dual-energy x-ray absorptiometry) scans of the distal ulna, distal radius, and hip and lumbar spine were also obtained. Analyses of covariance were performed to assess differences in limb lengths, adjusted for differences in stature. Multiple regression analyses were used to assess significant predictors of site-specific bone mass. Stature-adjusted means of limb lengths show that black boys have longer legs and humeri but shorter trunks than white boys. In addition, black children have longer forearms than white children, and girls have longer thighs than boys. The regression analysis demonstrated that site-specific bone mass was more strongly associated with regional segment length than stature, but this had little effect on the overall pattern of ethnic and sex differences. In conclusion, there is a differential effect of ethnicity and sex on the growth of the axial and appendicular skeletons, and regional segment length is a better predictor of site-specific bone mass than stature. Copyright 2005 Wiley-Liss, Inc.

Telomere Length in Aged Mayak PA Nuclear Workers Chronically Exposed to Internal Alpha and External Gamma Radiation.

PubMed

Scherthan, Harry; Sotnik, Natalia; Peper, Michel; Schrock, Gerrit; Azizova, Tamara; Abend, Michael

2016-06-01

Telomeres consist of GC-rich DNA repeats and the "shelterin" protein complex that together protect chromosome ends from fusion and degradation. Telomeres shorten with age due to incomplete end replication and upon exposure to environmental and intrinsic stressors. Exposure to ionizing radiation is known to modulate telomere length. However, the response of telomere length in humans chronically exposed to radiation is poorly understood. Here, we studied relative telomere length (RTL) by IQ-FISH to leukocyte nuclei in a group of 100 workers from the plutonium production facility at the Mayak Production Association (PA) who were chronically exposed to alpha-emitting ((239)Pu) radiation and/or gamma (photon) radiation, and 51 local residents serving as controls, with a similar mean age of about 80 years. We applied generalized linear statistical models adjusted for age at biosampling and the second exposure type on a linear scale and observed an age-dependent telomere length reduction. In those individuals with the lowest exposure, a significant reduction of about 20% RTL was observed, both for external gamma radiation (≤1 Gy) and internal alpha radiation (≤0.05-0.1 Gy to the red bone marrow). In highly exposed individuals (>0.1 Gy alpha, 1-1.5 Gy gamma), the RTL was similar to control. Stratification by gender revealed a significant (∼30%) telomere reduction in low-dose-exposed males, which was absent in females. While the gender differences in RTL may reflect different working conditions, lifestyle and/or telomere biology, absence of a dose response in the highly exposed individuals may reflect selection against cells with short telomeres or induction of telomere-protective effects. Our observations suggest that chronic systemic exposure to radiation leads to variable dose-dependent effects on telomere length.

Experimental Verification of the Streamline Curvature Numerical Analysis Method Applied to the Flow through an Axial Flow Fan.

DTIC Science & Technology

1980-05-28

Total Deviation Angles and Measured Inlet Axial Velocity . . . . 55 ix LIST OF FIGURES (Continued) Figure Page 19 Points Defining Blade Sections of...distance from leading edge to point of maximum camber along chord line ar tip vortex core radius AVR axial velocity ratio (Vx /V x c chord length CL tip...yaw ceoefficient d longitudinal distance from leading edge to tip vortex calculation point G distance from chord line to maximum camber point K cascade

Effects of flickering light on refraction and changes in eye axial length of C57BL/6 mice.

PubMed

Yu, Ying; Chen, Hui; Tuo, Jingsheng; Zhu, Yin

2011-01-01

To investigate the effectiveness and feasibility of inducing myopia in mice by flickering-light (FL) stimulation. Forty-five 28-day-old C57BL/6 (B6) mice were randomly assigned to three groups: control group, FL stimulation group and form deprivation (FD) group. Mice in the control group were raised under 250 lux illumination from 8:00 a.m. to 8:00 p.m. Mice in the FL group were raised under illumination with a duty cycle of 50% at a flash rate of 2 Hz from 8:00 a.m. to 8:00 p.m. for 6 weeks. Mice in the FD group were raised under the same conditions as the control group; the right eyes of the mice were covered with semitransparent hemispherical plastic shells serving as eye diffusers. The refractive state and axial length (AL) of the right eyes were measured by eccentric infrared photorefraction and A-scan ultrasonography, respectively, before treatment and after 2, 4, 6 or 8 weeks' treatment. After 6 weeks' exposure to FL, the refraction became more myopic compared with the control group as indicated by longer AL compared with the control group (p < 0.05); the FD eyes were more myopic than the FL eyes (p < 0.05). However, some mice lost their eye diffusers, and lens opacities were found. Myopia can be induced by FL in B6 mice. The myopic shift induced by FL is less than that induced by FD, but FL causes fewer side effects, and is safery and easier to manipulate. Copyright © 2011 S. Karger AG, Basel.

A comparison of lead lengths for mini-fyke nets to sample age-0 gar species

USGS Publications Warehouse

Long, James M.; Snow, Richard A.; Patterson, Chas P.

2016-01-01

Mini-fyke nets are often used to sample small-bodied fishes in shallow (<1 m depth) water, especially in vegetated shoreline habitats where seines are ineffective. Recent interest in gar (Lepisosteidae) ecology and conservation led us to explore the use of mini-fyke nets to capture age-0 gar and specifically how capture is affected by lead length of the fyke net. In the summers of 2012, 2013, and 2015, mini-fyke nets with two different lead lengths (4.57 m and 9.14 m) were set at random sites in backwaters and coves of the Red River arm of Lake Texoma, Oklahoma. Mean CPUE (catch-per-unit-effort; number per net night) was significantly lower for mini-fyke nets with short leads (0.52) compared to those with long leads (1.51). Additionally, Spotted Gar (Lepisosteus oculatus) were captured at a higher rate than the other three gar species present in Lake Texoma, although this could have been an artifact of sampling location. We found that differences in length-frequency of captured gar between gear types were nearly significant, with total length ranging from 47mm to 590mm. Mini-fyke nets with longer leads increased the efficiency of sampling for age-0 gar by increasing catch rate without affecting estimates of other population parameters and appear to be useful for this purpose. 

Reference curves of birth weight, length, and head circumference for gestational ages in Yogyakarta, Indonesia.

PubMed

Haksari, Ekawaty L; Lafeber, Harrie N; Hakimi, Mohammad; Pawirohartono, Endy P; Nyström, Lennarth

2016-11-21

The birth weight reference curve to estimate the newborns at risk in need of assessment and monitoring has been established. The previous reference curves from Indonesia, approximately 8 years ago, were based on the data collected from teaching hospitals only with limited gestational ages. The aims of the study were to update the reference curves for birth weight, supine length and head circumference for Indonesia, and to compare birth weight curves of boys and girls, first child and later children, and the ones in the previous studies. Data were extracted from the Maternal-Perinatal database between 1998-2007. Only live singletons with recorded gestational ages of 26 to 42 weeks and the exact time of admission to the neonatal facilities delivered or referred within 24 h of age to Sardjito Hospital, five district hospitals and five health centers in Yogyakarta Special Territory were included. Newborns with severely ill conditions, congenital anomaly and chromosomal abnormality were excluded. Smoothening of the curves was accomplished using a third-order polynomial equation. Our study included 54,599 singleton live births. Growth curves were constructed for boys (53.3%) and girls (46.7%) for birth weight, supine length, and head circumference. At term, mean birth weight for each gestational age of boys was significantly higher than that of girls. While mean birth weight for each gestational age of first-born-children, on the other hand was significantly lower than that of later-born-children. The mean birth weight was lower than that of Lubchenco's study. Compared with the previous Indonesian study by Alisyahbana, no differences were observed for the aterm infants, but lower mean birth weight was observed in preterm infants. Updated neonatal reference curves for birth weight, supine length and head circumference are important to classify high risk newborns in specific area and to identify newborns requiring attention.

Paternal age at birth is associated with offspring leukocyte telomere length in the nurses' health study.

PubMed

Prescott, J; Du, M; Wong, J Y Y; Han, J; De Vivo, I

2012-12-01

Is the association between paternal age at birth and offspring leukocyte telomere length (LTL) an artifact of early life socioeconomic status (SES)? Indicators of early life SES did not alter the relationship between paternal age at birth and offspring LTL among a population of white female nurses. Telomere length is considered a highly heritable trait. Recent studies report a positive correlation between paternal age at birth and offspring LTL. Maternal age at birth has also been positively associated with offspring LTL, but may stem from the strong correlation with paternal age at birth. The Nurses' Health Study (NHS) is an ongoing prospective cohort study of 121 700 female registered nurses who were enrolled in 1976. Great effort goes into maintaining a high degree of follow-up among our cohort participants (>95% of potential person-years). In 1989-1990, a subset of 32 826 women provided blood samples from which we selected participants for several nested case-control studies of telomere length and incident chronic disease. We used existing LTL data on a total of 4250 disease-free women who also reported maternal and paternal age at birth for this study. Nested case-control studies of stroke, myocardial infarction, cancers of the breast, endometrium, skin, pancreas and colon, as well as colon adenoma, were conducted within the blood sub-cohort. Each study used the following study design: for each case of a disease diagnosed after blood collection, a risk-set sampling scheme was used to select from one to three controls from the remaining participants in the blood sub-cohort who were free of that disease when the case was diagnosed. Controls were matched to cases by age at blood collection (± 1 year), date of blood collection (± 3 months), menopausal status, recent postmenopausal hormone use at blood collection (within 3 months, except for the myocardial infarction case-control study), as well as other factors carefully chosen for each individual study. The

Referral Patterns, Diagnosis, and Disease Management of Patients With Axial Spondyloarthritis

PubMed Central

van der Heijde, Désirée; Sieper, Joachim; Elewaut, Dirk; Deodhar, Atul; Pangan, Aileen L.; Dorr, Alexander P.

2014-01-01

Background Recognition, diagnosis, and management of axial spondyloarthritis (axial SpA) continue to advance. Objectives The objectives of this study were to compare referrals, diagnosis, and management of axial SpA in Western Europe (WE), North America (US and Canada), and the rest of world (RoW) in academic and community rheumatology practices and to identify areas for further education. Methods Rheumatologists responded online to the MAXIMA (Management of Axial SpA International and Multicentric Approaches) survey. Questions pertained to referral, diagnosis, and management of axial SpA. Results Rheumatologists (N = 809) from 56 countries completed the survey about patients with chronic back pain (≥3 months) starting before age 45 years. Responses from academic and community practice rheumatologists were generally similar. Most referrals were from primary care providers. Symptom duration of 3 years or more at referral was reported more frequently by WE and RoW than US respondents. More WE and RoW than US rheumatologists referred to the Assessment of SpondyloArthritis International Society criteria for axial SpA in clinical practice. Rheumatologists reported prescribing disease-modifying antirheumatic drugs for the management of axial SpA. Sulfasalazine was frequently prescribed across regions; methotrexate was more commonly prescribed by US rheumatologists compared with other regions. Conclusions Referral patterns, diagnosis, and disease management for axial SpA were similar among WE, North America, and RoW rheumatologists and in academic/community practices, although more WE and RoW rheumatologists referred to Assessment of SpondyloArthritis International Society criteria in clinical practice. Disease-modifying antirheumatic drugs were commonly prescribed for axial SpA patients, although it was unclear whether these were prescribed for axial or peripheral symptoms. PMID:25417676

Depressive Symptoms and Salivary Telomere Length in a Probability Sample of Middle-Aged and Older Adults

PubMed Central

Whisman, Mark A.; Richardson, Emily D.

2016-01-01

Objective To examine the association between depressive symptoms and salivary telomere length in a probability sample of middle-aged and older adults, evaluate age and sex as potential moderators of this association, and test whether this association was incremental to potential confounds. Methods Participants were 3,609 individuals from the 2008 wave of the Health and Retirement Study. Telomere length assays were performed using quantitative real-time polymerase chain reaction (qPCR) on DNA extracted from saliva samples. Depressive symptoms were assessed via interview, and health and lifestyle factors, traumatic life events, and neuroticism were assessed via self-report. Regression analyses were conducted to examine the associations between predictor variables and salivary telomere length. Results After adjusting for demographics, depressive symptoms were negatively associated with salivary telomere length (b = −.003, p = .014). Furthermore, this association was moderated by sex (b = .005, p = .011), such that depressive symptoms were significantly and negatively associated with salivary telomere length for men (b = −.006, p < .001) but not for women (b = −.001, p = .644). The negative association between depressive symptoms and salivary telomere length in men remained statistically significant after additionally adjusting for cigarette smoking, body mass index, chronic health conditions, childhood and lifetime exposure to traumatic life events, and neuroticism. Conclusions Higher levels of depressive symptoms were associated with shorter salivary telomeres in men and this association was incremental to several potential confounds. Shortened telomeres may help account for the association between depression and poor physical health and mortality. PMID:28029664

Accuracy of axial length measurements obtained by optical biometry and acoustic biometry in rhegmatogenous retinal detachment: a prospective study.

PubMed

Pongsachareonnont, Pear; Tangjanyatam, Sagol

2018-01-01

We compared the accuracy of axial length (AL) measurement obtained by optical biometry with that obtained by acoustic biometry in eyes with rhegmatogenous retinal detachment (RRD). This prospective descriptive analytic study measured the AL of eyes with RRD preoperatively and 3 months postoperatively using optical biometry (intraocular lens [IOL] master group) and acoustic biometry (immersion A-scan group). Preoperative and postoperative measurements were compared by paired t -test. The agreement between preoperative and postoperative measurements was analyzed using a Bland-Altman plot. Subgroup analysis of macular involvement status was performed. Twenty-seven eyes were analyzed in this study. The mean AL in the IOL master group was 23.58±0.97 mm preoperatively and 24.17±1.16 mm postoperatively; the mean difference was -0.59±0.90 mm ( P = 0.007). The mean AL in the immersion A-scan group was 24.29±1.59 mm preoperatively and 24.27±1.69 mm postoperatively; the mean difference was 0.02±0.48 mm ( P = 0.827). Bland-Altman analysis revealed disagreement between preoperative and postoperative AL measurements in both techniques. In subgroup analysis of macula with RRD, there were significant differences between preoperative and postoperative AL measurements in the IOL master group ( P = 0.014). Significant underestimation of AL measurement was observed when using the IOL master in eyes with RRD with macular involvement, which could affect IOL power selection.

Computational analysis of an axial flow pediatric ventricular assist device.

PubMed

Throckmorton, Amy L; Untaroiu, Alexandrina; Allaire, Paul E; Wood, Houston G; Matherne, Gaynell Paul; Lim, David Scott; Peeler, Ben B; Olsen, Don B

2004-10-01

Longer-term (>2 weeks) mechanical circulatory support will provide an improved quality of life for thousands of pediatric cardiac failure patients per year in the United States. These pediatric patients suffer from severe congenital or acquired heart disease complicated by congestive heart failure. There are currently very few mechanical circulatory support systems available in the United States as viable options for this population. For that reason, we have designed an axial flow pediatric ventricular assist device (PVAD) with an impeller that is fully suspended by magnetic bearings. As a geometrically similar, smaller scaled version of our axial flow pump for the adult population, the PVAD has a design point of 1.5 L/min at 65 mm Hg to meet the full physiologic needs of pediatric patients. Conventional axial pump design equations and a nondimensional scaling technique were used to estimate the PVAD's initial dimensions, which allowed for the creation of computational models for performance analysis. A computational fluid dynamic analysis of the axial flow PVAD, which measures approximately 65 mm in length by 35 mm in diameter, shows that the pump will produce 1.5 L/min at 65 mm Hg for 8000 rpm. Fluid forces (approximately 1 N) were also determined for the suspension and motor design, and scalar stress values remained below 350 Pa with maximum particle residence times of approximately 0.08 milliseconds in the pump. This initial design demonstrated acceptable performance, thereby encouraging prototype manufacturing for experimental validation.

Two- and three-dimensional CT measurements of urinary calculi length and width: a comparative study.

PubMed

Lidén, Mats; Thunberg, Per; Broxvall, Mathias; Geijer, Håkan

2015-04-01

The standard imaging procedure for a patient presenting with renal colic is unenhanced computed tomography (CT). The CT measured size has a close correlation to the estimated prognosis for spontaneous passage of a ureteral calculus. Size estimations of urinary calculi in CT images are still based on two-dimensional (2D) reformats. To develop and validate a calculus oriented three-dimensional (3D) method for measuring the length and width of urinary calculi and to compare the calculus oriented measurements of the length and width with corresponding 2D measurements obtained in axial and coronal reformats. Fifty unenhanced CT examinations demonstrating urinary calculi were included. A 3D symmetric segmentation algorithm was validated against reader size estimations. The calculus oriented size from the segmentation was then compared to the estimated size in axial and coronal 2D reformats. The validation showed 0.1 ± 0.7 mm agreement against reference measure. There was a 0.4 mm median bias for 3D estimated calculus length compared to 2D (P < 0.001), but no significant bias for 3D width compared to 2D. The length of a calculus in axial and coronal reformats becomes underestimated compared to 3D if its orientation is not aligned to the image planes. Future studies aiming to correlate calculus size with patient outcome should use a calculus oriented size estimation. © The Foundation Acta Radiologica 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Molecular Modeling of the Axial and Circumferential Elastic Moduli of Tubulin

PubMed Central

Zeiger, A. S.; Layton, B. E.

2008-01-01

Microtubules play a number of important mechanical roles in almost all cell types in nearly all major phylogenetic trees. We have used a molecular mechanics approach to perform tensile tests on individual tubulin monomers and determined values for the axial and circumferential moduli for all currently known complete sequences. The axial elastic moduli, in vacuo, were found to be 1.25 GPa and 1.34 GPa for α- and β-bovine tubulin monomers. In the circumferential direction, these moduli were 378 MPa for α- and 460 MPa for β-structures. Using bovine tubulin as a template, 269 homologous tubulin structures were also subjected to simulated tensile loads yielding an average axial elastic modulus of 1.10 ± 0.14 GPa for α-tubulin structures and 1.39 ± 0.68 GPa for β-tubulin. Circumferentially the α- and β-moduli were 936 ± 216 MPa and 658 ± 134 MPa, respectively. Our primary finding is that that the axial elastic modulus of tubulin diminishes as the length of the monomer increases. However, in the circumferential direction, no correlation exists. These predicted anisotropies and scale dependencies may assist in interpreting the macroscale behavior of microtubules during mitosis or cell growth. Additionally, an intergenomic approach to investigating the mechanical properties of proteins may provide a way to elucidate the evolutionary mechanical constraints imposed by nature upon individual subcellular components. PMID:18621829

Axial Crushing Behaviors of Thin-Walled Corrugated and Circular Tubes - A Comparative Study

NASA Astrophysics Data System (ADS)

Reyaz-Ur-Rahim, Mohd.; Bharti, P. K.; Umer, Afaque

2017-10-01

With the help of finite element analysis, this research paper deals with the energy absorption and collapse behavior with different corrugated section geometries of hollow tubes made of aluminum alloy 6060-T4. Literature available experimental data were used to validate the numerical models of the structures investigated. Based on the results available for symmetric crushing of circular tubes, models were developed to investigate corrugated thin-walled structures behavior. To study the collapse mechanism and energy absorbing ability in axial compression, the simulation was carried in ABAQUS /EXPLICIT code. In the simulation part, specimens were prepared and axially crushed to one-fourth length of the tube and the energy diagram of crushing force versus axial displacement is shown. The effect of various parameters such as pitch, mean diameter, corrugation, amplitude, the thickness is demonstrated with the help of diagrams. The overall result shows that the corrugated section geometry could be a good alternative to the conventional tubes.

[Intrauterine growth curves for body weight, body length, head circumference, chest circumference, and crown-rump length in 16 887 neonates with a gestational age of 27-42 weeks in Shenzhen, China].

PubMed

Huang, Xiao-Yun; Liu, Hui-Long; Lei, Min; Mai, Hui-Fen; Lian, Chao-Hui; Li, You-Cong

2017-08-01

To establish the intrauterine growth curves of neonates in Shenzhen, China and to investigate the intrauterine growth of neonates in Shenzhen. Cross-sectional cluster sampling was performed for an on-the-spot investigation of 16 887 neonates (9 418 males and 7 469 females) with a gestational age of 27-42 weeks who were born in two hospitals in Shenzhen from April 2013 to September 2015. The Lambda Mu Sigma (LMS) method was used for the curve fitting of body weight, body length, head circumference, chest circumference, and crown-rump length. The 3rd-97th percentile intrauterine growth curves for body weight, body length, head circumference, chest circumference, and crown-rump length were plotted for the neonates with a gestational age of 27-42 weeks who were divided into three groups (male, female, and mixed). The male neonates had significantly higher curves for the five indices than the female counterparts. The pattern and changing trend of body weight curves of these neonates were basically consistent with those in China Neonatal Network. The percentile intrauterine growth curves for body weight, body length, head circumference, chest circumference, and crown-rump length in neonates with a gestational age of 27-42 weeks in Shenzhen which has been established can provide a reference for clinical practice in the department of neonatology.

Differences in placental telomere length suggest a link between racial disparities in birth outcomes and cellular aging

PubMed Central

JONES, Christopher W.; GAMBALA, Cecilia; ESTEVES, Kyle C.; WALLACE, Maeve; SCHLESINGER, Reid; O’QUINN, Marguerite; KIDD, Laura; THEALL, Katherine P.; DRURY, Stacy S.

2017-01-01

BACKGROUND Health disparities begin early in life and persist across the life course. Despite current efforts Black women exhibit greater risk for pregnancy complications and negative perinatal outcomes compared to White women. The placenta, a complex multi-tissue organ, serves as the primary transducer of bidirectional information between the mother and fetus. Altered placental function is linked to multiple racially disparate pregnancy complications, however little is known about racial differences in molecular factors within the placenta. Several pregnancy complications, including preeclampsia and fetal growth restriction, exhibit racial disparities and are associated with shorter placental telomere length, an indicator of cellular stress and aging. Cellular senescence and telomere dynamics are linked to the molecular mechanisms associated with the onset of labor and parturition. Further, racial differences in telomere length are found in a range of different peripheral tissues. Together these factors suggest that exploration of racial differences in telomere length of the placenta may provide novel mechanistic insight into racial disparities in birth outcomes. OBJECTIVE This study examined whether telomere length measured in four distinct fetally-derived tissues were significantly different between Blacks and Whites. The study had two hypotheses: (1) that telomere length measured in different placental tissue types would be correlated and (2) that across all sampled tissues telomere length would differ by race. STUDY DESIGN In a prospective study, placental tissue samples were collected from the amnion, chorion, villus, and umbilical cord from Black and White singleton pregnancies (N=46). Telomere length was determined using monochrome multiplex quantitative real-time polymerase chain reaction in each placental tissue. Demographic and pregnancy-related data were also collected. Descriptive statistics characterized the sample overall and among Black and White

Effect of length of residence on overweight by region of birth and age at arrival among US immigrants.

PubMed

Oza-Frank, Reena; Narayan, K M Venkat

2010-06-01

To estimate associations between the length of residence and overweight among US immigrants by region of birth and age at arrival. Cross-sectional data from the National Health Interview Survey 1997-2005 were pooled. Multivariate-adjusted prevalence and OR were computed to test associations of length of residence and overweight. United States. Immigrant adults aged 18-74 years. The odds of being overweight were three times higher in migrants from Mexico, South America, Europe, Russia, Africa and the Middle East residing in the US for >15 years than their counterparts residing in the United States for <5 years. On the other hand, migrants from the Indian subcontinent and Southeast (SE) Asia had no association between the length of residence and overweight prevalence. Among both men and women, weight differences emerged as early as 5 years after arrival among those arriving at 18-24 years of age (OR 1.5-1.8). The odds of being overweight was higher among Hispanic men arriving before the age of 18 years than the European migrants (Mexico OR 1.7, 95 % CI 1.3, 2.2; South America OR 1.5, 95 % CI 1.0, 2.3), whereas the odds of being overweight among those from Africa and SE Asia was lower (OR 0.5, 95 % CI 0.3, 0.9 and OR 0.5, 95 % CI 0.4, 0.8, respectively). Among women who arrived at 25-44 years of age, the odds of being overweight among those from Africa and the Indian subcontinent was higher than the European migrants (OR 2.9, 95 % CI 1.7, 5.0 and OR 1.8, 95 % CI 1.8, 2.8, respectively). We found associations between the length of residence and overweight to vary by region of birth and age at arrival, highlighting the importance of these characteristics in assessing overweight risk among the US immigrants.

Theoretical analysis of the axial growth of nanowires starting with a binary eutectic droplet via vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Liu, Qing; Li, Hejun; Zhang, Yulei; Zhao, Zhigang

2018-06-01

A series of theoretical analysis is carried out for the axial vapor-liquid-solid (VLS) growth of nanowires starting with a binary eutectic droplet. The growth model considering the entire process of axial VLS growth is a development of the approaches already developed by previous studies. In this model, the steady and unsteady state growth are considered both. The amount of solute species in a variable liquid droplet, the nanowire length, radius, growth rate and all other parameters during the entire axial growth process are treated as functions of growth time. The model provides theoretical predictions for the formation of nanowire shape, the length-radius and growth rate-radius dependences. It is also suggested by the model that the initial growth of single nanowire is significantly affected by Gibbs-Thompson effect due to the shape change. The model was applied on predictions of available experimental data of Si and Ge nanowires grown from Au-Si and Au-Ge systems respectively reported by other works. The calculations with the proposed model are in satisfactory agreement with the experimental results of the previous works.

Bicuspid aortic valves: diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT.

PubMed

Murphy, David J; McEvoy, Sinead H; Iyengar, Sri; Feuchtner, Gudrun; Cury, Ricardo C; Roobottom, Carl; Baumueller, Stephan; Alkadhi, Hatem; Dodd, Jonathan D

2014-08-01

To assess the diagnostic accuracy of standard axial 64-slice chest CT compared to aortic valve image plane ECG-gated cardiac CT for bicuspid aortic valves. The standard axial chest CT scans of 20 patients with known bicuspid aortic valves were blindly, randomly analyzed for (i) the appearance of the valve cusps, (ii) the largest aortic sinus area, (iii) the longest aortic cusp length, (iv) the thickest aortic valve cusp and (v) valve calcification. A second blinded reader independently analyzed the appearance of the valve cusps. Forty-two age- and sex-matched patients with known tricuspid aortic valves were used as controls. Retrospectively ECG-gated cardiac CT multiphase reconstructions of the aortic valve were used as the gold-standard. Fourteen (21%) scans were scored as unevaluable (7 bicuspid, 7 tricuspid). Of the remainder, there were 13 evaluable bicuspid valves, ten of which showed an aortic valve line sign, while the remaining three showed a normal Mercedes-Benz appearance owing to fused valve cusps. The 35 evaluable tricuspid aortic valves all showed a normal Mercedes-Benz appearance (P=0.001). Kappa analysis=0.62 indicating good interobserver agreement for the aortic valve cusp appearance. Aortic sinus areas, aortic cusp lengths and aortic cusp thicknesses of ≥ 3.8 cm(2), 3.2 cm and 1.6mm respectively on standard axial chest CT best distinguished bicuspid from tricuspid aortic valves (P<0.0001 for all). Of evaluable scans, the sensitivity, specificity, positive and negative predictive values of standard axial chest CT in diagnosing bicuspid aortic valves was 77% (CI 0.54-1.0), 100%, 100% and 70% respectively. The aortic valve is evaluable in approximately 80% of standard chest 64-slice CT scans. Bicuspid aortic valves may be diagnosed on evaluable scans with good diagnostic accuracy. An aortic valve line sign, enlarged aortic sinuses and elongated, thickened valve cusps are specific CT features. Copyright © 2014 Elsevier Ireland Ltd. All rights

Aging and cardiovascular complexity: effect of the length of RR tachograms

PubMed Central

Nagaraj, Nithin

2016-01-01

As we age, our hearts undergo changes that result in a reduction in complexity of physiological interactions between different control mechanisms. This results in a potential risk of cardiovascular diseases which are the number one cause of death globally. Since cardiac signals are nonstationary and nonlinear in nature, complexity measures are better suited to handle such data. In this study, three complexity measures are used, namely Lempel–Ziv complexity (LZ), Sample Entropy (SampEn) and Effort-To-Compress (ETC). We determined the minimum length of RR tachogram required for characterizing complexity of healthy young and healthy old hearts. All the three measures indicated significantly lower complexity values for older subjects than younger ones. However, the minimum length of heart-beat interval data needed differs for the three measures, with LZ and ETC needing as low as 10 samples, whereas SampEn requires at least 80 samples. Our study indicates that complexity measures such as LZ and ETC are good candidates for the analysis of cardiovascular dynamics since they are able to work with very short RR tachograms. PMID:27957395

Relative Leukocyte Telomere Length, Hematological Parameters and Anemia - Data from the Berlin Aging Study II (BASE-II).

PubMed

Meyer, Antje; Salewsky, Bastian; Buchmann, Nikolaus; Steinhagen-Thiessen, Elisabeth; Demuth, Ilja

2016-01-01

The length of the chromosome ends, telomeres, is widely accepted as a biomarker of aging. However, the dynamic of the relationship between telomere length and hematopoietic parameters in the normal aging process, which is of particular interest with respect to age-related anemia, is not well understood. We have analyzed the relationship between relative leukocyte telomere length (rLTL) and several hematological parameters in the older group of the Berlin Aging Study II (BASE-II) participants. This paper also compares rLTL between both BASE-II age groups (22-37 and 60-83 years). Genomic DNA was extracted from peripheral blood leukocytes of BASE-II participants and used to determine rLTL by a quantitative PCR protocol. Standard methods were used to determine blood parameters, and the WHO criteria were used to identify anemic participants. Telomere length data were available for 444 younger participants (28.4 ± 3.1 years old; 52% women) and 1,460 older participants (68.2 ± 3.7 years old; 49.4% women). rLTL was significantly shorter in BASE-II participants of the older group (p = 3.7 × 10-12) and in women (p = 4.2 × 10-31). rLTL of older men exhibited a statistically significant, positive partial correlation with mean corpuscular hemoglobin (MCH; p = 0.012) and MCH concentration (p = 0.002). While these correlations were only observed in men, the rLTL of older women was negatively correlated with the number of thrombocytes (p = 0.015) in the same type of analysis. Among all older participants, 6% met the criteria to be categorized as 'anemic'; however, there was no association between anemia and rLTL. In the present study, we have detected isolated correlations between rLTL and hematological parameters; however, in all cases, rLTL explained only a small part of the variation of the analyzed parameters. In disagreement with some other studies showing similar data, we interpret the association between rLTL and some of the hematological parameters studied here to be

Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model.

PubMed

Johnson, Eric G; Swenarton, Mary Katherine

2016-01-01

The effective management of invasive species requires detailed understanding of the invader's life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish ( Pterois volitans/miles ) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water.

Age, growth and population structure of invasive lionfish (Pterois volitans/miles) in northeast Florida using a length-based, age-structured population model

PubMed Central

2016-01-01

The effective management of invasive species requires detailed understanding of the invader’s life history. This information is essential for modeling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Indo-Pacific lionfish (Pterois volitans/miles) have rapidly invaded the western Atlantic, Gulf of Mexico and Caribbean Sea with documented negative impacts on native ecosystems. To better understand the life history of this species, we developed and validated a length-based, age-structured model to investigate age, growth and population structure in northeast Florida. The main findings of this study were: (1) lionfish exhibited rapid growth with seasonal variation in growth rates; (2) distinct cohorts were clearly identifiable in the length-frequency data, suggesting that lionfish are recruiting during a relatively short period in summer; and (3) the majority of lionfish were less than two years old with no lionfish older than three years of age, which may be the result of culling efforts as well as ontogenetic habitat shifts to deeper water. PMID:27920953

Study on axial strength of a channel-shaped pultruded GFRP member

NASA Astrophysics Data System (ADS)

Matsumoto, Yukihiro; Satake, Chito; Nisida, Kenji

2017-10-01

Fiber reinforced polymers (FRP) are widely used in vehicle and aerospace applications because of their lightweight and high-strength characteristics. Additionally, FRPs are increasingly applied to building structures. However, the elastic modulus of glass fiber reinforced polymers (GFRPs) is lower than that of steel. Hence, the evaluating the buckling strength of GFRP members for design purpose is necessary. The buckling strength is determined by Euler buckling mode as well as local buckling. In this study investigated the compressive strength of GFRP members subjected to axial compression through experiments and theoretical calculations. The adopted GFRP member was a channel-shaped GFRP, which was molded via pultrusion, at various lengths. Although, the mechanical properties as longitudinal elastic modulus and fiber volume fraction and strength of GFRP members subjected, to axial can be easily evaluated, evaluating transverse elastic modulus and shear modulus in typical material tests is difficult in standard section. Therefore the composite law was used in this study. As a result, we confirmed that the axial strength of a GFRP member could be calculated by a theoretical evaluation method utilizing longitudinal elastic modulus and fiber volume fraction.

Measurement of minority carrier diffusion lengths in GaAs nanowires by a nanoprobe technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Darbandi, A.; Watkins, S. P., E-mail: simonw@sfu.ca

Minority carrier diffusion lengths in both p-type and n-type GaAs nanowires were studied using electron beam induced current by means of a nanoprobe technique without lithographic processing. The diffusion lengths were determined for Au/GaAs rectifying junctions as well as axial p-n junctions. By incorporating a thin lattice-matched InGaP passivating shell, a 2-fold enhancement in the minority carrier diffusion lengths and one order of magnitude reduction in the surface recombination velocity were achieved.

Axial interaction free-electron laser

DOEpatents

Carlsten, Bruce E.

1997-01-01

Electron orbits from a helical axial wiggler in an axial guide field are absolutely unstable as power is extracted from the particles. For off-axis beams an axial FEL mechanism exists when the axial electric field in a TM mode is wiggled to interact with the axial velocity of the electrons that form the beam. The interaction strength is comparable to that for helical FELs and is insensitive to beam orbit errors. The orbits for this mechanism are extremely stable in the absence of space charge and lead to high extraction efficiencies without particle phasing incoherence or interception. This interaction mechanism is suitable for use with intense annular electron beams for high power generation at microwave frequencies.

Axial interaction free-electron laser

DOEpatents

Carlsten, B.E.

1997-09-02

Electron orbits from a helical axial wiggler in an axial guide field are absolutely unstable as power is extracted from the particles. For off-axis beams an axial FEL mechanism exists when the axial electric field in a TM mode is wiggled to interact with the axial velocity of the electrons that form the beam. The interaction strength is comparable to that for helical FELs and is insensitive to beam orbit errors. The orbits for this mechanism are extremely stable in the absence of space charge and lead to high extraction efficiencies without particle phasing incoherence or interception. This interaction mechanism is suitable for use with intense annular electron beams for high power generation at microwave frequencies. 5 figs.

Significant Axial Elongation with Minimal Change in Refraction in 3- to 6-Year-Old Chinese Preschoolers: The Shenzhen Kindergarten Eye Study.

PubMed

Guo, Xinxing; Fu, Min; Ding, Xiaohu; Morgan, Ian G; Zeng, Yangfa; He, Mingguang

2017-12-01

To document the distribution of ocular biometry and to evaluate its associations with refraction in a group of Chinese preschoolers. Population-based cross-sectional study. A total of 1133 preschoolers 3 to 6 years of age from 8 representative kindergartens. Biometric measurements including axial length (AL), anterior chamber depth (ACD), and corneal radius of curvature (CR) were obtained from partial-coherence laser interferometry (IOL Master; Carl Zeiss Meditec, Oberkochen, Germany) before cycloplegia. Lens power (LP) and AL-to-CR ratio were calculated. Cycloplegic refraction (3 drops of 1% cyclopentolate) was measured using an autorefractor (KR8800; Topcon Corp., Tokyo, Japan), and spherical equivalent refraction (SER) was calculated. Biometric and refractive parameters were assessed as a function of age and gender. Multiple regression analysis was performed to explore the associations between refraction and ocular biometry. Ocular biometric distributions and their relationships to refraction. Among the 1127 children (99.5%) with successful cycloplegic refraction, mean SER was 1.37±0.63 diopters (D). Prevalence of myopia increased from 0% at 3 years of age to 3.7% (95% confidence interval, 1.0%-6.5%) at 6 years of age. Biometric parameters followed Gaussian distributions with means of 22.39±0.68 mm for AL, 7.79±0.25 mm for CR, and 24.61±1.42 D for calculated LP; and non-Gaussian distributions with means of 3.34±0.24 mm for ACD and 2.88±0.06 for AL-to-CR ratio. Axial length, ACD, and AL-to-CR ratio increased from 3 to 6 years of age, CR remained stable, whereas LP declined. Overall, SER declined slightly. For the SER variance, AL explained 18.6% and AL-to-CR ratio explained 39.8%, whereas AL, CR, and LP accounted for 80.0% after adjusting for age and gender. Young Chinese children are predominantly mildly hyperopic, with a low prevalence of myopia by the age of 6 years. An increase of 1 mm in AL was associated with only 0.45 D of myopic change. Decreases in

Choroidal Thickness in 3001 Chinese Children Aged 6 to 19 Years Using Swept-Source OCT

PubMed Central

Xiong, Shuyu; He, Xiangui; Deng, Junjie; Lv, Minzhi; Jin, Jiali; Sun, Sifei; Yao, Chunxia; Zhu, Jianfeng; Zou, Haidong; Xu, Xun

2017-01-01

The purpose of the cross-sectional study is to describe the values and distribution of choroidal thickness and to explore its related factors, especially age, in Chinese children. A total of 3001 Chinese school children aged 6 to 19 years underwent comprehensive ophthalmic examinations, including axial length and cycloplegic refraction. Choroidal thickness was measured by swept-source optical coherence tomography (SS-OCT). There was a greater difference in the more central regions between the myopes and emmetropes. Multiple regression analysis was performed to determine the associated factors of choroidal thickness. The results demonstrated that age was independently positively related to choroidal thickness for emmetropes (β = 3.859, p < 0.001), and mild myopes with spherical equivalent greater than −2.00 D (−1.25 D < spherical equivalent ≤ −0.50 D: β = 3.476, p = 0.006; −2.00 D < spherical equivalent ≤ −1.25 D: β = 3.232, p = 0.020). However, no significant relationship between age and choroidal thickness was found in children with spherical equivalent ≤ −2.00 D, suggesting that the protective effect of physiologic choroidal growth with age against rapid axial elongation disappeared while axial elongation becomes the dominant determinant of choroidal thickness among children with myopia worse than −2.00 D. PMID:28327553

Exact analytic solution for the spin-up maneuver of an axially symmetric spacecraft

NASA Astrophysics Data System (ADS)

Ventura, Jacopo; Romano, Marcello

2014-11-01

The problem of spinning-up an axially symmetric spacecraft subjected to an external torque constant in magnitude and parallel to the symmetry axis is considered. The existing exact analytic solution for an axially symmetric body is applied for the first time to this problem. The proposed solution is valid for any initial conditions of attitude and angular velocity and for any length of time and rotation amplitude. Furthermore, the proposed solution can be numerically evaluated up to any desired level of accuracy. Numerical experiments and comparison with an existing approximated solution and with the integration of the equations of motion are reported in the paper. Finally, a new approximated solution obtained from the exact one is introduced in this paper.

Moving towards high-power, high-frequency and low-resistance CNT supercapacitors by tuning the CNT length, axial deformation and contact resistance

NASA Astrophysics Data System (ADS)

Basiricò, L.; Lanzara, G.

2012-08-01

In this paper it is shown that the electrochemical behaviour of vertically aligned multi-walled carbon nanotube (VANT) supercapacitors is influenced by the VANTs’ length (electrode thickness), by their axial compression and by their interface with the current collector. It is found that the VANTs, which can be interpreted as a dense array of nanochannels, have an active area available to ions that is strongly affected by the electrode’s thickness and compressional state. Consequently, the tested thinner electrodes, compressed electrodes or a combination of the two were found to be characterized by a significant improvement in terms of power density (up to 1246%), knee frequency (58 822% working up to 10 kHz), equivalent series resistance (ESR, up to 67%) and capacitance (up to 21%) when compared with thicker and/or uncompressed electrodes. These values are significantly higher than those reported in the literature where long VANTs with no control on compression are typically used. It is also shown that the ESR can be reduced not only by using shorter and compressed VANTs that have a higher conductance or by improving the electrode/collector electrical contact by changing the contact morphology at the nanoscale through compression, but also by depositing a thin platinum layer on the VANT tips in contact with the current collector (73% ESR decrease).

Moving towards high-power, high-frequency and low-resistance CNT supercapacitors by tuning the CNT length, axial deformation and contact resistance.

PubMed

Basiricò, L; Lanzara, G

2012-08-03

In this paper it is shown that the electrochemical behaviour of vertically aligned multi-walled carbon nanotube (VANT) supercapacitors is influenced by the VANTs' length (electrode thickness), by their axial compression and by their interface with the current collector. It is found that the VANTs, which can be interpreted as a dense array of nanochannels, have an active area available to ions that is strongly affected by the electrode's thickness and compressional state. Consequently, the tested thinner electrodes, compressed electrodes or a combination of the two were found to be characterized by a significant improvement in terms of power density (up to 1246%), knee frequency (58,822% working up to 10 kHz), equivalent series resistance (ESR, up to 67%) and capacitance (up to 21%) when compared with thicker and/or uncompressed electrodes. These values are significantly higher than those reported in the literature where long VANTs with no control on compression are typically used. It is also shown that the ESR can be reduced not only by using shorter and compressed VANTs that have a higher conductance or by improving the electrode/collector electrical contact by changing the contact morphology at the nanoscale through compression, but also by depositing a thin platinum layer on the VANT tips in contact with the current collector (73% ESR decrease).

Age-related changes in optical and biometric characteristics of emmetropic eyes.

PubMed

Atchison, David A; Markwell, Emma L; Kasthurirangan, Sanjeev; Pope, James M; Smith, George; Swann, Peter G

2008-04-28

We measured optical and biometric parameters of emmetropic eyes as a function of age. There were approximately 20 subjects each in age groups 18-29, 30-39, 40-49, 50-59, and 60-69 years with similar male and female numbers. One eye was tested for each subject, having spherical equivalent in the range -0.88 D to +0.75 D and age changes: anterior chamber depth decreased 0.011 mm/year, lens central thickness increased 0.024 mm/year, anterior segment depth increased 0.013 mm/year, eye length increased 0.011 mm/year, anterior lens radius of curvature decreased 0.044 mm/year, and lens equivalent refractive index decreased 0.0003/year. Males had higher anterior corneal radii of curvature (0.16 mm), lower lens equivalent refractive index (0.006), longer vitreous lengths (0.51 mm), and longer axial lengths (0.62 mm) than females. Superficially, the results suggest that eyes get bigger as they age. However, results can be related to refraction patterns in which refraction is stable in 20s to 40s and then moves in the hypermetropic direction. It is likely that several young subjects will become hypermetropic as they age, and it is possible that some of the older subjects were myopic when younger.

Inflammation, But Not Telomere Length, Predicts Successful Ageing at Extreme Old Age: A Longitudinal Study of Semi-supercentenarians.

PubMed

Arai, Yasumichi; Martin-Ruiz, Carmen M; Takayama, Michiyo; Abe, Yukiko; Takebayashi, Toru; Koyasu, Shigeo; Suematsu, Makoto; Hirose, Nobuyoshi; von Zglinicki, Thomas

2015-10-01

To determine the most important drivers of successful ageing at extreme old age, we combined community-based prospective cohorts: Tokyo Oldest Old Survey on Total Health (TOOTH), Tokyo Centenarians Study (TCS) and Japanese Semi-Supercentenarians Study (JSS) comprising 1554 individuals including 684 centenarians and (semi-)supercentenarians, 167 pairs of centenarian offspring and spouses, and 536 community-living very old (85 to 99 years). We combined z scores from multiple biomarkers to describe haematopoiesis, inflammation, lipid and glucose metabolism, liver function, renal function, and cellular senescence domains. In Cox proportional hazard models, inflammation predicted all-cause mortality with hazard ratios (95% CI) 1.89 (1.21 to 2.95) and 1.36 (1.05 to 1.78) in the very old and (semi-)supercentenarians, respectively. In linear forward stepwise models, inflammation predicted capability (10.8% variance explained) and cognition (8(.)6% variance explained) in (semi-)supercentenarians better than chronologic age or gender. The inflammation score was also lower in centenarian offspring compared to age-matched controls with Δ (95% CI) = - 0.795 (- 1.436 to - 0.154). Centenarians and their offspring were able to maintain long telomeres, but telomere length was not a predictor of successful ageing in centenarians and semi-supercentenarians. We conclude that inflammation is an important malleable driver of ageing up to extreme old age in humans.

Inflammation, But Not Telomere Length, Predicts Successful Ageing at Extreme Old Age: A Longitudinal Study of Semi-supercentenarians

PubMed Central

Arai, Yasumichi; Martin-Ruiz, Carmen M.; Takayama, Michiyo; Abe, Yukiko; Takebayashi, Toru; Koyasu, Shigeo; Suematsu, Makoto; Hirose, Nobuyoshi; von Zglinicki, Thomas

2015-01-01

To determine the most important drivers of successful ageing at extreme old age, we combined community-based prospective cohorts: Tokyo Oldest Old Survey on Total Health (TOOTH), Tokyo Centenarians Study (TCS) and Japanese Semi-Supercentenarians Study (JSS) comprising 1554 individuals including 684 centenarians and (semi-)supercentenarians, 167 pairs of centenarian offspring and spouses, and 536 community-living very old (85 to 99 years). We combined z scores from multiple biomarkers to describe haematopoiesis, inflammation, lipid and glucose metabolism, liver function, renal function, and cellular senescence domains. In Cox proportional hazard models, inflammation predicted all-cause mortality with hazard ratios (95% CI) 1.89 (1.21 to 2.95) and 1.36 (1.05 to 1.78) in the very old and (semi-)supercentenarians, respectively. In linear forward stepwise models, inflammation predicted capability (10.8% variance explained) and cognition (8.6% variance explained) in (semi-)supercentenarians better than chronologic age or gender. The inflammation score was also lower in centenarian offspring compared to age-matched controls with Δ (95% CI) = − 0.795 (− 1.436 to − 0.154). Centenarians and their offspring were able to maintain long telomeres, but telomere length was not a predictor of successful ageing in centenarians and semi-supercentenarians. We conclude that inflammation is an important malleable driver of ageing up to extreme old age in humans. PMID:26629551

Differences in placental telomere length suggest a link between racial disparities in birth outcomes and cellular aging.

PubMed

Jones, Christopher W; Gambala, Cecilia; Esteves, Kyle C; Wallace, Maeve; Schlesinger, Reid; O'Quinn, Marguerite; Kidd, Laura; Theall, Katherine P; Drury, Stacy S

2017-03-01

Health disparities begin early in life and persist across the life course. Despite current efforts, black women exhibit greater risk for pregnancy complications and negative perinatal outcomes compared with white women. The placenta, which is a complex multi-tissue organ, serves as the primary transducer of bidirectional information between the mother and fetus. Altered placental function is linked to multiple racially disparate pregnancy complications; however, little is known about racial differences in molecular factors within the placenta. Several pregnancy complications, which include preeclampsia and fetal growth restriction, exhibit racial disparities and are associated with shorter placental telomere length, which is an indicator of cellular stress and aging. Cellular senescence and telomere dynamics are linked to the molecular mechanisms that are associated with the onset of labor and parturition. Further, racial differences in telomere length are found in a range of different peripheral tissues. Together these factors suggest that exploration of racial differences in telomere length of the placenta may provide novel mechanistic insight into racial disparities in birth outcomes. This study examined whether telomere length measured in 4 distinct fetally derived tissues were significantly different between black and white women. The study had 2 hypotheses: (1) that telomere length that is measured in different placental tissue types would be correlated and (2) that across all sampled tissues telomere length would differ by race. In a prospective study, placental tissue samples were collected from the amnion, chorion, villus, and umbilical cord from black and white singleton pregnancies (N=46). Telomere length was determined with the use of monochrome multiplex quantitative real-time polymerase chain reaction in each placental tissue. Demographic and pregnancy-related data were also collected. Descriptive statistics characterized the sample overall and among

Axial and radial diffusivity in preterm infants who have diffuse white matter changes on magnetic resonance imaging at term-equivalent age.

PubMed

Counsell, Serena J; Shen, Yuji; Boardman, James P; Larkman, David J; Kapellou, Olga; Ward, Philip; Allsop, Joanna M; Cowan, Frances M; Hajnal, Joseph V; Edwards, A David; Rutherford, Mary A

2006-02-01

Diffuse excessive high signal intensity (DEHSI) is observed in the majority of preterm infants at term-equivalent age on conventional MRI, and diffusion-weighted imaging has shown that apparent diffusion coefficient values are elevated in the white matter (WM) in DEHSI. Our aim was to obtain diffusion tensor imaging on preterm infants at term-equivalent age and term control infants to test the hypothesis that radial diffusivity was significantly different in the WM in preterm infants with DEHSI compared with both preterm infants with normal-appearing WM on conventional MRI and term control infants. Diffusion tensor imaging was obtained on 38 preterm infants at term-equivalent age and 8 term control infants. Values for axial (lambda1) and radial [(lambda2 + lambda3)/2] diffusivity were calculated in regions of interest positioned in the central WM at the level of the centrum semiovale, frontal WM, posterior periventricular WM, occipital WM, anterior and posterior portions of the posterior limb of the internal capsule, and the genu and splenium of the corpus callosum. Radial diffusivity was elevated significantly in the posterior portion of the posterior limb of the internal capsule and the splenium of the corpus callosum, and both axial and radial diffusivity were elevated significantly in the WM at the level of the centrum semiovale, the frontal WM, the periventricular WM, and the occipital WM in preterm infants with DEHSI compared with preterm infants with normal-appearing WM and term control infants. There was no significant difference between term control infants and preterm infants with normal-appearing WM in any region studied. These findings suggest that DEHSI represents an oligodendrocyte and/or axonal abnormality that is widespread throughout the cerebral WM.

Microwave electron cyclotron electron resonance (ECR) ion source with a large, uniformly distributed, axially symmetric, ECR plasma volume

DOEpatents

Alton, Gerald D.

1996-01-01

An electron cyclotron resonance (ECR) ion source includes a primary mirror coil disposed coaxially around a vacuum vessel in which a plasma is induced and introducing a solenoidal ECR-producing field throughout the length of the vacuum vessel. Radial plasma confinement is provided by a multi-cusp, multi-polar permanent magnet array disposed azimuthally around the vessel and within the primary mirror coil. Axial confinement is provided either by multi-cusp permanent magnets at the opposite axial ends of the vessel, or by secondary mirror coils disposed on opposite sides of the primary coil.

The Frequency Versus Length Response for a Deformed SLIFER Cable.

DTIC Science & Technology

1980-02-01

lux- 0 Vph where o M the frequency of the oscillator when the length of the shorted cable is zero (it depends only on the internal inductance of the...form of Eq. (2) that takes into account the characteristic impedance of the cable. x = harctan Y j- x tan . (12) WX cWxW( Vph ) For a co-axial cable, the

Length and weight of very low birth weight infants in Germany at 2 years of age: does it matter at what age they start complementary food?

PubMed

Spiegler, J; Eisemann, N; Ehlers, S; Orlikowsky, T; Kannt, O; Herting, E; Göpel, W

2015-06-01

We analysed at what age parents start complementary food in very low birth weight infants, determined risk factors for early introduction of complementary food (post-term age) and analysed whether the age at introduction of complementary food influences height or weight at 2 years of age. Parents of premature infants born in 2009-2011 answered questionnaires regarding introduction of complementary food in the first year of life (N=2262) and were followed up at a post-term age of 2 years (N=981). Length and weight were compared with full-term infants from the KiGGs study. Logistic and linear regression analyses were conducted to study predictors for early introduction of complementary food and the influence of age at introduction of complementary food on later height and weight. Average age at introduction of complementary food was 3.5 months post-term age. The lower the gestational age at birth, the earlier (post-term age) vegetables and meat were introduced. Age at introduction of complementary food was influenced by intrauterine growth restriction, gestational age at birth, maternal education and a developmental delay perceived by the parents. Length and weight at a post-term age of 2 years was not negatively influenced by early introduction of complementary food. VLBW infants are introduced to complementary food on average before a post-term age of 4 months. There was no negative effect of early introduction of complementary food on height and weight at 2 years of age.

Color discrimination errors associate with axial motor impairments in Parkinson's disease.

PubMed

Bohnen, Nicolaas I; Haugen, Jacob; Ridder, Andrew; Kotagal, Vikas; Albin, Roger L; Frey, Kirk A; Müller, Martijn L T M

2017-01-01

Visual function deficits are more common in imbalance-predominant compared to tremor-predominant PD suggesting a pathophysiological role of impaired visual functions in axial motor impairments. To investigate the relationship between changes in color discrimination and motor impairments in PD while accounting for cognitive or other confounder factors. PD subjects (n=49, age 66.7±8.3 years; Hoehn & Yahr stage 2.6±0.6) completed color discrimination assessment using the Farnsworth-Munsell 100 Hue Color Vision Test, neuropsychological, motor assessments and [ 11 C]dihydrotetrabenazine vesicular monoamine transporter type 2 PET imaging. MDS-UPDRS sub-scores for cardinal motor features were computed. Timed up and go mobility and walking tests were assessed in 48 subjects. Bivariate correlation coefficients between color discrimination and motor variables were significant only for the Timed up and go (R S =0.44, P=0.0018) and the MDS-UPDRS axial motor scores (R S =0.38, P=0.0068). Multiple regression confounder analysis using the Timed up and go as outcome parameter showed a significant total model (F (5,43) = 7.3, P<0.0001) with significant regressor effects for color discrimination (standardized β=0.32, t=2.6, P=0.012), global cognitive Z-score (β=-0.33, t=-2.5, P=0.018), duration of disease (β=0.26, t=1.8, P=0.038), but not for age or striatal dopaminergic binding. The color discrimination test was also a significant independent regressor in the MDS-UPDRS axial motor model (standardized β=0.29, t=2.4, P=0.022; total model t (5,43) = 6.4, P=0.0002). Color discrimination errors associate with axial motor features in PD independent of cognitive deficits, nigrostriatal dopaminergic denervation, and other confounder variables. These findings may reflect shared pathophysiology between color discrimination visual impairments and axial motor burden in PD.

Are gestational age, birth weight, and birth length indicators of favorable fetal growth conditions? A structural equation analysis of Filipino infants.

PubMed

Bollen, Kenneth A; Noble, Mark D; Adair, Linda S

2013-07-30

The fetal origins hypothesis emphasizes the life-long health impacts of prenatal conditions. Birth weight, birth length, and gestational age are indicators of the fetal environment. However, these variables often have missing data and are subject to random and systematic errors caused by delays in measurement, differences in measurement instruments, and human error. With data from the Cebu (Philippines) Longitudinal Health and Nutrition Survey, we use structural equation models, to explore random and systematic errors in these birth outcome measures, to analyze how maternal characteristics relate to birth outcomes, and to take account of missing data. We assess whether birth weight, birth length, and gestational age are influenced by a single latent variable that we call favorable fetal growth conditions (FFGC) and if so, which variable is most closely related to FFGC. We find that a model with FFGC as a latent variable fits as well as a less parsimonious model that has birth weight, birth length, and gestational age as distinct individual variables. We also demonstrate that birth weight is more reliably measured than is gestational age. FFGCs were significantly influenced by taller maternal stature, better nutritional stores indexed by maternal arm fat and muscle area during pregnancy, higher birth order, avoidance of smoking, and maternal age 20-35 years. Effects of maternal characteristics on newborn weight, length, and gestational age were largely indirect, operating through FFGC. Copyright © 2013 John Wiley & Sons, Ltd.

Comminuted supracondylar femoral fractures: a biomechanical analysis comparing the stability of medial versus lateral plating in axial loading.

PubMed

Briffa, Nikolai; Karthickeyan, Raju; Jacob, Joshua; Khaleel, Arshad

2016-11-01

The aim of this study was to compare the biomechanical properties of medial and lateral plating of a medially comminuted supracondylar femoral fracture. A supracondylar femoral fracture model comparing two fixation methods was tested cyclically in axial loading. One-centimetre supracondylar gap osteotomies were created in six synthetic femurs approximately 6 cm proximal to the knee joint. There were two constructs investigated: group 1 and group 2 were stabilized with an 8-hole LC-DCP, medially and laterally, respectively. Both construct groups were axially loaded. Global displacement (total length), wedge displacement, bending moment and strain were measured. Medial plating showed a significantly decreased displacement, bending moment and strain at the fracture site in axial loading. Medial plating of a comminuted supracondylar femur fracture is more stable than lateral plating.

Transitions in axial morphology along the Southeast Indian Ridge

NASA Astrophysics Data System (ADS)

Ma, Ying; Cochran, James R.

1996-07-01

Shipboard bathymetric and magnetic profiles across the Southeast Indian Ridge (SEIR) were analyzed in order to examine the nature of along-axis variations in axial morphology at this intermediate spreading rate ridge. Three types of axial morphology are observed along the SEIR: an axial high, a shallow (200-700 m deep) axial valley and a deep (>1000 m deep) axial valley. An axial high is found to the east of the Australian-Antarctic Discordance (AAD) (east of 128°E) and between 82°E and 104°E. A shallow rift valley is found from 104°E to 114°E and from 82°E westward past the Amerstdam/St. Paul hotspot (ASP) to about 30°S, 75°E. Deep rift valleys are found from 114°E to 128°E in the vicinity of the AAD and from the Indian Ocean Triple Junction (IOTJ) at 25°S, 70°E to about 30°S, 75°E. The transition near 30°S occurs in an area of constant zero-age depth and does not appear to result from an increase in mantle temperature. It could be the result of the rapid increase in spreading rate along that portion of the SEIR. The most likely cause of the other transitions in axial morphology is variations in mantle temperature. The transitions between the different types of axial morphology are well defined and occur over a limited distance. Transitions in axial morphology are accompanied by significant changes in ridge flank topographic roughness. The transitions from axial valleys to axial highs are also accompanied by changes in the amplitude of the seafloor magnetic anomalies. Our observations suggest that there are distinct modes rather than a continuum of axial morphology on the SEIR and that there appears to be a "threshold" mechanism for a rapid change between different states of axial morphology. The ASP has only a limited influence on the SEIR. The ridge axis is marked by an axial valley for the entire distance from the IOTJ up to and past the ASP. The ridge axis becomes shallower as the ASP is approached from the northwest but only by about 300 m over

Telomere length analysis in Down syndrome birth.

PubMed

Bhaumik, Pranami; Bhattacharya, Mandar; Ghosh, Priyanka; Ghosh, Sujay; Kumar Dey, Subrata

2017-06-01

Human reproductive fitness depends upon telomere chemistry. Maternal age, meiotic nondisjunction error and telomere length of mother of trisomic child are someway associated. Reports exhibiting maternal inheritance of telomere length in Down syndrome child are very scanty. To investigate this, we collected peripheral blood from 170 mothers of Down syndrome child and 186 age matched mothers of euploid child with their newly born babies. Telomere length was measured by restriction digestion - southern blotting technique. Meiotic nondisjunction error was detected by STR genotyping. Subjects are classified by age (old >35 years and young ˂35 years) and by meiotic error (MI and MII). Linear regression was run to explore the age - telomere length relationship in each maternal groups. The study reveals that with age, telomere erodes in length. Old MII mothers carry the shortest (p˂0.001), control mothers have the longest telomere and MI lies in between. Babies from older mother have longer telomere (p˂0.001) moreover; telomeres are longer in Down syndrome babies than control babies (p˂0.001). To conclude, this study represents not only the relation between maternal aging and telomere length but also explore the maternal heritability of telomere length in families with Down syndrome child. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in diffusion path length with old age in diffuse optical tomography

NASA Astrophysics Data System (ADS)

Bonnéry, Clément; Leclerc, Paul-Olivier; Desjardins, Michèle; Hoge, Rick; Bherer, Louis; Pouliot, Philippe; Lesage, Frédéric

2012-05-01

Diffuse, optical near infrared imaging is increasingly being used in various neurocognitive contexts where changes in optical signals are interpreted through activation maps. Statistical population comparison of different age or clinical groups rely on the relative homogeneous distribution of measurements across subjects in order to infer changes in brain function. In the context of an increasing use of diffuse optical imaging with older adult populations, changes in tissue properties and anatomy with age adds additional confounds. Few studies investigated these changes with age. Duncan et al. measured the so-called diffusion path length factor (DPF) in a large population but did not explore beyond the age of 51 after which physiological and anatomical changes are expected to occur [Pediatr. Res. 39(5), 889-894 (1996)]. With increasing interest in studying the geriatric population with optical imaging, we studied changes in tissue properties in young and old subjects using both magnetic resonance imaging (MRI)-guided Monte-Carlo simulations and time-domain diffuse optical imaging. Our results, measured in the frontal cortex, show changes in DPF that are smaller than previously measured by Duncan et al. in a younger population. The origin of these changes are studied using simulations and experimental measures.

Comparison of anterior segment parameters and axial length measurements performed on a Scheimpflug device with biometry function and a reference optical biometer.

PubMed

Muzyka-Woźniak, Maria; Oleszko, Adam

2018-04-26

To compare measurements of axial length (AL), corneal curvature (K), anterior chamber depth (ACD) and white-to-white (WTW) distance on a new device combining Scheimpflug camera and partial coherence interferometry (Pentacam AXL) with a reference optical biometer (IOL Master 500). To evaluate differences between IOL power calculations based on the two biometers. Ninety-seven eyes of 97 consecutive cataract or refractive lens exchange patients were examined preoperatively on IOL Master 500 and Pentacam AXL units. Comparisons between two devices were performed for AL, K, ACD and WTW. Intraocular lens (IOL) power targeting emmetropia was calculated with SRK/T and Haigis formulas on both devices and compared. There were statistically significant differences between two devices for all measured parameters (P < 0.05), except ACD (P = 0.36). Corneal curvature measured with Pentacam AXL was significantly flatter then with IOL Master. The mean difference in AL was clinically insignificant (0.01 mm; 95% LoA 0.16 mm). Pentacam AXL yielded higher IOL power in 75% of eyes for Haigis formula and in 62% of eyes for SRK/T formula, with a mean difference within ± 0.5 D for 72 and 86% of eyes, respectively. There were statistically significant differences between AL, K and WTW measurements obtained with the compared biometers. Flatter corneal curvature measurements on Pentacam AXL necessitate formulas optimisation for Pentacam AXL.

Strength and stability analysis of a single-walled black phosphorus tube under axial compression

NASA Astrophysics Data System (ADS)

Cai, Kun; Wan, Jing; Wei, Ning; Qin, Qing H.

2016-07-01

Few-layered black phosphorus materials currently attract much attention due to their special electronic properties. As a consequence, a single-layer black phosphorus (SLBP) nanotube has been theoretically built. The corresponding electronic properties of such a black phosphorus nanotube (BPNT) were also evaluated numerically. However, unlike graphene formed with 2sp2 covalent carbon atoms, SLBP is formed with 3sp3 bonded atoms. It means that the structure from SLBP will possess lower Young’s modulus and mechanical strength than those of carbon nanotubes. In this study, molecular dynamics simulation is performed to investigate the strength and stability of BPNTs affected by the factors of diameter, length, loading speed and temperature. Results are fundamental for investigating the other physical properties of a BPNT acting as a component in a nanodevice. For example, buckling of the BPNT happens earlier than fracture, before which the nanostructure has very small axial strain. For the same BPNT, a higher load speed results in lower critical axial strain and a nanotube with lower axial strain can still be stable at a higher temperature.

Axial static mixer

DOEpatents

Sandrock, H.E.

1982-05-06

Static axial mixing apparatus includes a plurality of channels, forming flow paths of different dimensions. The axial mixer includes a flow adjusting device for adjustable selective control of flow resistance of various flow paths in order to provide substantially identical flows through the various channels, thereby reducing nonuniform coating of interior surfaces of the channels. The flow adjusting device may include diaphragm valves, and may further include a pressure regulating system therefor.

Performance of the SRK/T formula using A-Scan ultrasound biometry after phacoemulsification in eyes with short and long axial lengths.

PubMed

Karabela, Yunus; Eliacik, Mustafa; Kaya, Faruk

2016-07-08

eyes (94.74 %) for short ALs and (70.97 %) for long ALs were within ±1 D of the predicted refractive error. No significant relationship with PE and IOL types, AL, K1, K2, IOL power, and attempted value, besides with MAE and AL, K1, K2, age, attempted, achieved value were found in both groups. The SRK/T formula performs well and shows good predictability in eyes with short and long axial lengths.

Numerical study of axial turbulent flow over long cylinders

NASA Technical Reports Server (NTRS)

Neves, J. C.; Moin, P.; Moser, R. D.

1991-01-01

The effects of transverse curvature are investigated by means of direct numerical simulations of turbulent axial flow over cylinders. Two cases of Reynolds number of about 3400 and layer-thickness-to-cylinder-radius ratios of 5 and 11 were simulated. All essential turbulence scales were resolved in both calculations, and a large number of turbulence statistics were computed. The results are compared with the plane channel results of Kim et al. (1987) and with experiments. With transverse curvature the skin friction coefficient increases and the turbulence statistics, when scaled with wall units, are lower than in the plane channel. The momentum equation provides a scaling that collapses the cylinder statistics, and allows the results to be interpreted in light of the plane channel flow. The azimuthal and radial length scales of the structures in the flow are of the order of the cylinder diameter. Boomerang-shaped structures with large spanwise length scales were observed in the flow.

Synthesis, fabrication and characterization of Ge/Si axial nanowire heterostructure tunnel FETs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Picraux, Samuel T; Dayeh, Shadi A

2010-01-01

Axial Ge/Si heterostructure nanowires allow energy band-edge engineering along the axis of the nanowire, which is the charge transport direction, and the realization of asymmetric devices for novel device architectures. This work reports on two advances in the area of heterostructure nanowires and tunnel FETs: (i) the realization of 100% compositionally modulated Si/Ge axial heterostructure nanowires with lengths suitable for device fabrication and (ii) the design and implementation of Schottky barrier tunnel FETs on these nanowires for high-on currents and suppressed ambipolar behavior. Initial prototype devices resulted in a current drive in excess of 100 {micro}A/{micro}m (I/{pi}D) and 10{sup 5}more » I{sub on}/I{sub off} ratios. These results demonstrate the potential of such asymmetric heterostructures (both in the semiconductor channel and metal-semiconductor barrier heights) for low-power and high performance electronics.« less

Confocal microscopy using variable-focal-length microlenses and an optical fiber bundle.

PubMed

Yang, Lisong; Mac Raighne, Aaron; McCabe, Eithne M; Dunbar, L Andrea; Scharf, Toralf

2005-10-01

The use of variable-focal-length (VFL) microlenses can provide a way to axially scan the foci across a sample by electronic control. We demonstrate an approach to coupling VFL microlenses individually to a fiber bundle as a way to create a high-throughput aperture array with a controllable aperture pattern. It would potentially be applied in real-time confocal imaging in vivo for biological specimens. The VFL microlenses that we used consist of a liquid-crystal film sandwiched between a pair of conductive substrates for which one has a hole-patterned electrode. One obtains the variation of the focal length by changing the applied voltage. The fiber bundle has been characterized by coupling with both coherent and incoherent light sources. We further demonstrate the use of a VFL microlens array in combination with the fiber bundle to build up a confocal system. The axial response of the confocal system has been measured without mechanical movement of the sample or the objective, and the FWHM is estimated to be approximately 16 microm, with asymmetric sidelobes.

Measuring axial pump thrust

DOEpatents

Suchoza, Bernard P.; Becse, Imre

1988-01-01

An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices.

Sports and Exercise at Different Ages and Leukocyte Telomere Length in Later Life--Data from the Berlin Aging Study II (BASE-II).

PubMed

Saßenroth, Denise; Meyer, Antje; Salewsky, Bastian; Kroh, Martin; Norman, Kristina; Steinhagen-Thiessen, Elisabeth; Demuth, Ilja

2015-01-01

Physical activity and sports have repeatedly been reported to be associated with telomere length. We studied the association of different types of sports across different stages of life on relative leukocyte telomere length (rLTL) in advanced age.815 participants (397 men) from the Berlin Aging Study II aged over 61 years were included in the analysis. rLTL was measured by real time PCR and physical activity was determined retrospectively by questionnaire, assessing type and duration of sports in the past as well as currently. Five separate multiple linear regression models adjusted for various control variables were performed. 67.3% of participants exercised currently, whereas 19.4% performed sports only between the age of 20 and 30. rLTL was higher in subjects who stated to exercise currently (N = 456), and in subjects who engaged in endurance (N = 138) or intensive activity sports (N = 32). Current physical activity was positively associated with rLTL in the risk factor adjusted regression model (β = 0.26, p < 0.001) and practicing sports for a minimum of 10 years preceding the assessment had a significant effect on rLTL (β = 0.39, p = 0.011). The highest impact was seen for intensive activity sports (β = 0.79, p < 0.001) and physical activity since at least 42 years (β = 0.47, p = 0.001). However, physical activity only between 20 and 30 years of age did not affect rLTL in old age when compared to no sports at all (β = -0.16, p = 0.21). Physical activity is clearly associated with longer rLTL. The effect is seen with longer periods of physical activity (at least 10 years), with intensive sports activities having the greatest impact on rLTL. Our data suggest that regular physical activity for at least 10 years is necessary to achieve a sustained effect on rLTL.

Rasterstereographic analysis of axial back surface rotation in standing versus forward bending posture in idiopathic scoliosis.

PubMed

Hackenberg, Lars; Hierholzer, Eberhard; Bullmann, Viola; Liljenqvist, Ulf; Götze, Christian

2006-07-01

The forward bending test according to Adams and rib hump quantification by scoliometer are common clinical examination techniques in idiopathic scoliosis, although precise data about the change of axial surface rotation in forward bending posture are not available. In a pilot study the influence of leg length inequalities on the back shape of five normal subjects was clarified. Then 91 patients with idiopathic scoliosis with Cobb-angles between 20 degrees and 82 degrees were examined by rasterstereography, a 3D back surface analysis system. The axial back surface rotation in standing posture was compared with that in forward bending posture and additionally with a scoliometer measurement in forward bending posture. The changes of back shape in forward bending posture were correlated with the Cobb-angle, the level of the apex of the scoliotic primary curve and the age of the patient. Averaged over all patients, the back surface rotation amplitude increased from 23.1 degrees in standing to 26.3 degrees in forward bending posture. The standard deviation of this difference was high (6.1 degrees ). The correlation of back surface rotation amplitude in standing with that in forward bending posture was poor (R (2)=0.41) as was the correlation of back surface rotation in standing posture with the scoliometer in forward bending posture measured rotation (R (2)=0.35). No significant correlation could be found between the change of back shape in forward bending and the degree of deformity (R (2)=0.07), likewise no correlation with the height of the apex of the scoliosis (R (2)=0.005) and the age of the patient (R (2)=0.001). Before forward bending test leg length inequalities have to be compensated accurately. Compared to the standing posture, forward bending changes back surface rotation. However, this change varies greatly between patients, and is independent of the type and degree of scoliosis. Furthermore remarkable differences were found between scoliometer measurement

CONTRIBUTION OF AXIAL MOTOR IMPAIRMENT TO PHYSICAL INACTIVITY IN PARKINSON'S DISEASE

PubMed Central

Bryant, Mon S; Hou, Jyhgong Gabriel; Collins, Robert L; Protas, Elizabeth J

2015-01-01

Objective To investigate the relationships between motor symptoms of Parkinson’s disease (PD) and activity limitations in persons with PD. Design/Methods Cross-sectional study of persons with mild to moderate PD (N=90). Associations among axial motor features, limb motor signs, the Physical Activity Scale for Elders (PASE), the ability to perform Activities of Daily Living (ADL) and level of ADL dependency were studied. A composite score of axial motor features included the following UPDRS items: speech, rigidity of the neck, arising from chair, posture, gait and postural stability. A composite score of limb motor signs included the following UPDRS items: tremor at rest of all extremities, action tremor, rigidity of all extremities, finger taps, hand movement, rapid alternating hand movements and foot tapping. Results Axial motor features of PD were significantly correlated with physical inactivity (p<.001), decreased ADL (p<.001) and increase in ADL dependency (p<.001). Limb motor signs significantly correlated with decreased ADL (p<.001) and level of ADL dependency (p=.035), but was not correlated with physical inactivity. After controlling for age, gender, disease duration and comorbidity, axial motor features contributed significantly to physical inactivity, decreased ADL and increase in ADL dependency, whereas the limb motor signs did not. Conclusions Axial motor impairment contributed to physical inactivity and decreased ability to perform ADLs in persons with PD. PMID:26368837

Axial vector Z‧ and anomaly cancellation

NASA Astrophysics Data System (ADS)

Ismail, Ahmed; Keung, Wai-Yee; Tsao, Kuo-Hsing; Unwin, James

2017-05-01

Whilst the prospect of new Z‧ gauge bosons with only axial couplings to the Standard Model (SM) fermions is widely discussed, examples of anomaly-free renormalisable models are lacking in the literature. We look to remedy this by constructing several motivated examples. Specifically, we consider axial vectors which couple universally to all SM fermions, as well as those which are generation-specific, leptophilic, and leptophobic. Anomaly cancellation typically requires the presence of new coloured and charged chiral fermions, and we argue that in a large class of models masses of these new states are expected to be comparable to that of the axial vector. Finally, an axial vector mediator could provide a portal between SM and hidden sector states, and we also consider the possibility that the axial vector couples to dark matter. If the dark matter relic density is set due to freeze-out via the axial vector, this strongly constrains the parameter space.

Intraoperative floppy iris syndrome and its association with various concurrent medications, bulbus length, patient age and gender.

PubMed

Wahl, Michael; Tipotsch-Maca, Saskia M; Vecsei-Marlovits, Pia V

2017-01-01

To evaluate the association between intraoperative floppy iris syndrome (IFIS) and concurrent medications containing selective alpha1A receptor antagonists as well as nonselective alpha1-adrenergic receptor antagonists, bulbus length, patient age and gender. We performed a prospective data acquisition of IFIS occurrence and grading, and retrospective evaluation of concurrent medications, bulbus length, patient age and gender of all patients undergoing cataract surgery over a 6-month period. IFIS was observed in 119 of 947 cases (12.6 %). 31 of those 119 patients (26.1 %) had a concurrent medication with a drug that is associated with a higher risk of causing IFIS. Tamsulosin was the drug most commonly associated with IFIS (n = 11), followed by a combination of drugs (n = 7), doxazosin (n = 4), quetiapine (n = 4), finasterid (n = 2), prothipendyl (n = 2), and mianserin (n = 1). Bulbus length and age did not show any significant association with occurrence or grade of IFIS. Gender distribution among IFIS cases was 57.1 % males (n = 68) and 42.9 % (n = 51) females. The occurrence of IFIS has to be expected with a variety of concurrent medications. The number of IFIS cases and the percentage of females in this series are higher compared to previous reports. The observations might be due to a rising awareness of surgeons or to an increasing number of causative medications on the market.

Telomere length regulation during cloning, embryogenesis and ageing.

PubMed

Schaetzlein, S; Rudolph, K L

2005-01-01

Telomeres are nucleoprotein complexes at the end of eukaryotic chromosomes with an essential role in chromosome capping. Owing to the end-replication problem of DNA polymerase, telomeres shorten during each cell division. When telomeres become critically short, they loose their capping function, which in turn induces a DNA damage-like response. This mechanism inhibits cell proliferation at the senescence stage and there is evidence that it limits the regenerative capacity of tissues and organs during chronic diseases and ageing. The holoenzyme telomerase synthesises telomeric DNA de novo, but, in humans, it is active only during embryogenesis, in immature germ cells and in a subset of stem/progenitor cells during postnatal life. Telomere length can be maintained or increased by telomerase, a process that appears to be regulated by a variety of telomere-binding proteins that control telomerase recruitment and activity at the telomeres. During embryogenesis, telomerase is strongly activated at the morula/blastocyst transition. At this transition, telomeres are significantly elongated in murine and bovine embryos. Early embryonic telomere elongation is telomerase dependent and leads to a rejuvenation of telomeres in cloned bovine embryos. Understanding of the molecular mechanisms underlying this early embryonic telomere elongation programme is of great interest for medical research in the fields of regeneration, cell therapies and therapeutic cloning.

Experimental Studies on Strength Behaviour of Notched Glass/Epoxy Laminated Composites under Uni-axial and Bi-axial Loading

NASA Astrophysics Data System (ADS)

Guptha, V. L. Jagannatha; Sharma, Ramesh S.

2017-11-01

The use of FRP composite materials in aerospace, aviation, marine, automotive and civil engineering industry has increased rapidly in recent years due to their high specific strength and stiffness properties. The structural members contrived from such composite materials are generally subjected to complex loading conditions and leads to multi-axial stress conditions at critical surface localities. Presence of notches, much required for joining process of composites, makes it further significant. The current practice of using uni-axial test data alone to validate proposed material models is inadequate leading to evaluation and consideration of bi-axial test data. In order to correlate the bi-axial strengths with the uni-axial strengths of GFRP composite laminates in the presence of a circular notch, bi-axial tests using four servo-hydraulic actuators with four load cells were carried out. To determine the in-plane strength parameters, bi-axial cruciform test specimen model was considered. Three different fibre orientations, namely, 0°, 45°, and 90° are considered with a central circular notch of 10 mm diameter in the present investigation. From the results obtained, it is observed that there is a reduction in strength of 5.36, 2.41 and 13.92% in 0°, 45°, and 90° fibre orientation, respectively, under bi-axial loading condition as compared to that of uni-axial loading in laminated composite.

Association between leukocyte telomere length and bone mineral density in women 25-93 years of age.

PubMed

Nielsen, Barbara Rubek; Linneberg, Allan; Bendix, Laila; Harboe, Maria; Christensen, Kaare; Schwarz, Peter

2015-06-01

Leukocyte telomere length (LTL) and bone mineral density (BMD) are associated with health and mortality. Because osteoporosis is an age-related condition and LTL is considered to be a biomarker of aging, we hypothesized that shorter LTL could predict lower BMD. The aim of our study was to assess whether there is an association of LTL with BMD and to determine whether this possible association is independent of age. The BMDs of the lumbar spine (LS), femoral neck (FN) and total hip (TH) were evaluated in 460 women using DXA. LTL was analyzed using quantitative polymerase chain reaction. The women completed a health and lifestyle questionnaire. The associations were estimated by regression models that considered age, body mass index (BMI), menopause, physical activity, alcohol consumption and smoking habits. We found a statistically significant unadjusted association between LTL and age (estimate and 95% confidence interval (CI): -0.003 (-0.005; -0.002)); and between BMI adjusted age and logarithmic transformed BMD. Estimates and 95% CI were as follows: LS: -0.13 (-0.26; -0.01); right TH: -0.44 (-0.53; -0.34); left TH: -0.38 (-0.48; -0.28); right FN: -0.57 (-0.67; -0.46) and left FN: -0.51 (-0.62; -0.40). There were no statistically significant associations between BMD and LTL (both logarithmically transformed) with or without age adjustments. The age-adjusted estimates and CI were as follows: LS: -0.10 (-0.71; 0.52); right TH: -0.13 (-0.66; 0.41); left TH: -0.13 (-0.67; 0.42); right FN: -0.03 (-0.58; 0.52) and left FN: 0.09 (-0.47; 0.66). In conclusion, we found no statistically significant associations between BMD and LTL, although the estimates of the crude associations were all positive, indicating hypothesis consistency; that shorter LTL predict lower BMD values. This positive association was no longer apparent after adjusting for age. As expected, age was statistically significantly associated with both telomere length and BMI adjusted BMD. Copyright © 2015

Endocarditis associated with vertebral osteomyelitis and septic arthritis of the axial skeleton.

PubMed

Murillo, Oscar; Grau, Imma; Gomez-Junyent, Joan; Cabrera, Celina; Ribera, Alba; Tubau, Fe; Peña, Carmen; Ariza, Javier; Pallares, Roman

2018-04-01

The relationship between infective endocarditis (IE) and osteoarticular infections (OAIs) are not well known. We aimed to study the characteristics of patients with IE and OAIs, and the interactions between these two infections. An observational study (1993-2014) which includes two cohorts: (1) patients with IE (n = 607) and (2) patients with bacteremic OAIs (n = 458; septic arthritis of peripheral and axial skeleton, and vertebral and peripheral osteomyelitis). These two cohorts were prospectively collected, and we retrospectively reviewed the clinical and microbiological variables. There were 70 cases of IE with concomitant OAIs, representing 11.5% of IE cases and 15% of bacteremic OAI cases. Among cases with IE, the associated OAIs mainly involved the axial skeleton (n = 54, 77%): 43 were vertebral osteomyelitis (61%), mainly caused by "less virulent" bacteria (viridans and bovis streptococci, enterococci, and coagulase-negative staphylococci), and 15 were septic arthritis of the axial skeleton (21%), which were mainly caused by Staphylococcus aureus. OAIs with involvement of the axial skeleton were associated with IE (adjusted OR = 2.2; 95% CI 1.1-4.3) independently of age, sex, and microorganisms. Among patients with IE, the associated OAIs mainly involve the axial skeleton. Transesophageal echocardiography should be carefully considered in patients presenting with these bacteremic OAIs.

A mini axial and a permanent maglev radial heart pump.

PubMed

Qian, Kun-Xi; Ru, Wei-Min; Wang, Hao; Jing, Teng

2007-05-31

The implantability and durability have been for decades the focus of artificial heart R&D. A mini axial and a maglev radial pump have been developed to meet with such requirements.The mini axial pump weighing 27g (incl.5g rotor) has an outer diameter of 21mm and a length of 10mm in its largest point, but can produce a maximal blood flow of 6l/min with 50mmHg pressure increase. Therefore, it is suitable for the patients of 40-60kg body weight. For other patients of 60-80kg or 80-100kg body weight, the mini axial pumps of 23mm and 25mm outer diameter had been developed before, these devices were acknowledged to be the world smallest LVADs by Guinness World Record Center in 2004.The permanent maglev radial pump weighing 150g is a shaft-less centrifugal pump with permanent magnetic bearings developed by the author. It needs no second coil for suspension of the rotor except the motor coil, different from all other maglev pumps developed in USA, Japan, European, etc. Thus no detecting and controlling systems as well as no additional power supply for maglev are necessary. The pump can produce a blood flow up to as large as 10l/min against 100mmHg pressure.An implantable and durable blood pump will be a viable alternative to natural donor heart for transplantation.

Split Venturi, Axially-Rotated Valve

DOEpatents

Walrath, David E.; Lindberg, William R.; Burgess, Robert K.

2000-08-29

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane.

Measuring axial pump thrust

DOEpatents

Suchoza, B.P.; Becse, I.

1988-11-08

An apparatus for measuring the hydraulic axial thrust of a pump under operation conditions is disclosed. The axial thrust is determined by forcing the rotating impeller off of an associated thrust bearing by use of an elongate rod extending coaxially with the pump shaft. The elongate rod contacts an impeller retainer bolt where a bearing is provided. Suitable measuring devices measure when the rod moves to force the impeller off of the associated thrust bearing and the axial force exerted on the rod at that time. The elongate rod is preferably provided in a housing with a heat dissipation mechanism whereby the hot fluid does not affect the measuring devices. 1 fig.

Analysis of nonlinear axial vibration of single-walled carbon nanotubes using Homotopy perturbation method

NASA Astrophysics Data System (ADS)

Fatahi-Vajari, A.; Azimzadeh, Z.

2018-05-01

This paper investigates the nonlinear axial vibration of single-walled carbon nanotubes (SWCNTs) based on Homotopy perturbation method (HPM). A second order partial differential equation that governs the nonlinear axial vibration for such nanotubes is derived using doublet mechanics (DM) theory. To obtain the nonlinear natural frequency in axial vibration mode, this nonlinear equation is solved using HPM. The influences of some commonly used boundary conditions, amplitude of vibration, changes in vibration modes and variations of the nanotubes geometrical parameters on the nonlinear axial vibration characteristics of SWCNTs are discussed. It was shown that unlike the linear one, the nonlinear natural frequency is dependent to maximum vibration amplitude. Increasing the maximum vibration amplitude decreases the natural frequency of vibration compared to the predictions of the linear models. However, with increase in tube length, the effect of the amplitude on the natural frequency decreases. It was also shown that the amount and variation of nonlinear natural frequency is more apparent in higher mode vibration and two clamped boundary conditions. To show the accuracy and capability of this method, the results obtained herein were compared with the fourth order Runge-Kuta numerical results and good agreement was observed. It is notable that the results generated herein are new and can be served as a benchmark for future works.

Short-term absence from industry: I Literature, definitions, data, and the effect of age and length of service

PubMed Central

Froggatt, P.

1970-01-01

Froggatt, P. (1970).Brit. J. industr. Med.,27, 199-210. Short-term absence from industry. I. Literature, definitions, data, and the effect of age and length of service. This, with two subsequent papers, comprises the first extensive study directed only to short-term absence from industry, an entity common in all branches of organized work and now one of the greatest personnel problems of an industrial society. This first paper reviews the literature and background of industrial absence, describes the sources of the data and the groups for study, defines terms used throughout, discusses the rationale of the selection criteria, and examines the effect on the numbers of one-day and two-day absences of age and length of service in the organization. The observations are from two light engineering works and two government departments and cover in all some 2 300 male and female personnel, both salaried and hourly-paid, over periods of up to seven years. Twenty study groups were identified for the analyses, each comprising members of similar `works centre', sex, supervisory grade, and marital status, who neither changed relevant status during the study period nor were absent for more than 65 days in any year. This stringency in delimitation enhanced the validity of the conclusions drawn by (a) ensuring necessary homogeneity for crucial variables, and (b) permitting examination of the consistency of the results over groups and organizations. Multiple regression analysis for the effect of age and length of service on short-term absence showed that, generally, length of service had no effect but that age was (weakly) negatively linearly associated with the number of one-day absences but independent of the number of two-day absences. Transforming the skewed dependent variates to normal functions for completely valid analysis had no important effect on these results, which were also confirmed by data from a longitudinal study in one company. This association between age and one

Development an efficient calibrated nonlocal plate model for nonlinear axial instability of zirconia nanosheets using molecular dynamics simulation.

PubMed

Sahmani, S; Fattahi, A M

2017-08-01

New ceramic materials containing nanoscaled crystalline phases create a main object of scientific interest due to their attractive advantages such as biocompatibility. Zirconia as a transparent glass ceramic is one of the most useful binary oxides in a wide range of applications. In the present study, a new size-dependent plate model is constructed to predict the nonlinear axial instability characteristics of zirconia nanosheets under axial compressive load. To accomplish this end, the nonlocal continuum elasticity of Eringen is incorporated to a refined exponential shear deformation plate theory. A perturbation-based solving process is put to use to derive explicit expressions for nonlocal equilibrium paths of axial-loaded nanosheets. After that, some molecular dynamics (MD) simulations are performed for axial instability response of square zirconia nanosheets with different side lengths, the results of which are matched with those of the developed nonlocal plate model to capture the proper value of nonlocal parameter. It is demonstrated that the calibrated nonlocal plate model with nonlocal parameter equal to 0.37nm has a very good capability to predict the axial instability characteristics of zirconia nanosheets, the accuracy of which is comparable with that of MD simulation. Copyright © 2017 Elsevier Inc. All rights reserved.

Length of residence, age and patterns of medicinal plant knowledge and use among women in the urban Amazon

PubMed Central

2014-01-01

Background This paper explores patterns of women’s medicinal plant knowledge and use in an urban area of the Brazilian Amazon. Specifically, this paper examines the relationship between a woman’s age and her use and knowledge of medicinal plants. It also examines whether length of residence in three different areas of the Amazon is correlated with a woman’s use and knowledge of medicinal plants. Two of the areas where respondents may have resided, the jungle/seringal and farms/colonias, are classified as rural. The third area (which all of the respondents resided in) was urban. Methods This paper utilizes survey data collected in Rio Branco, Brazil. Researchers administered the survey to 153 households in the community of Bairro da Luz (a pseudonym). The survey collected data on phytotherapeutic knowledge, general phytotherapeutic practice, recent phytotherapeutic practice and demographic information on age and length of residence in the seringal, on a colonia, and in a city. Bivariate correlation coefficients were calculated to assess the inter-relationships among the key variables. Three dependent variables, two measuring general phytotherapeutic practice and one measuring phytotherapeutic knowledge were regressed on the demographic factors. Results The results demonstrate a relationship between a woman’s age and medicinal plant use, but not between age and plant knowledge. Additionally, length of residence in an urban area and on a colonia/farm are not related to medicinal plant knowledge or use. However, length of residence in the seringal/jungle is positively correlated with both medicinal plant knowledge and use. Conclusions The results reveal a vibrant tradition of medicinal plant use in Bairro da Luz. They also indicate that when it comes to place of residence and phytotherapy the meaningful distinction is not rural versus urban, it is seringal versus other locations. Finally, the results suggest that phytotherapeutic knowledge and use should be

Gravidity is not associated with telomere length in a biracial cohort of middle-aged women: The Coronary Artery Risk Development in Young Adults (CARDIA) study

PubMed Central

Puterman, Eli; Gunderson, Erica P.; Chan, Cheeling; Hou, Lifang; Carnethon, Mercedes

2017-01-01

Objective Having experienced 2–3 births is associated with reduced mortality versus women with <2 or ≥4 births. The effect of 2–3 births on lifespan may be associated with delayed cellular aging. We hypothesized telomere length, a marker of cellular aging, would be longer in women who had 2–3 pregnancies. Methods Leukocyte telomere length was measured using quantitative real-time polymerase chain reaction in 620 women in CARDIA at the year 15 and 20 exams, expressed as the ratio of telomere repeat copy number to single-copy gene copy number (T/S). Number of pregnancies at the time of telomere length measurement was obtained (mean age = 41±0.1 years, average gravidity = 2.64±0.1 pregnancies). Participants were divided into 4 groups by number of pregnancies: 0, 1, 2–3, and ≥4, to test for differences in telomere length by gravidity group. Results The mean and SD for telomere length was 0.98 ± 0.20 T/S in the whole cohort. There were no differences in mean telomere length between groups; 0.98±0.02 T/S in women with 0 pregnancies, 1.01±0.02 T/S in women with 1 pregnancy, 0.97±0.01 T/S in women with 2–3 pregnancies, and 0.99±0.02 T/S in women with ≥4 pregnancies (p = 0.51). We defined high-risk (shorter) telomere length as ≤25th percentile, and low-risk (longer) telomere length as ≥75 percentile. There were no differences in the prevalence of high-risk or low-risk telomere length between gravidity groups. Conclusions Gravidity was not associated with telomere length in early middle age; the protective association of 2–3 births may act through other mechanisms. PMID:29049398

Gravidity is not associated with telomere length in a biracial cohort of middle-aged women: The Coronary Artery Risk Development in Young Adults (CARDIA) study.

PubMed

Lane-Cordova, Abbi D; Puterman, Eli; Gunderson, Erica P; Chan, Cheeling; Hou, Lifang; Carnethon, Mercedes

2017-01-01

Having experienced 2-3 births is associated with reduced mortality versus women with <2 or ≥4 births. The effect of 2-3 births on lifespan may be associated with delayed cellular aging. We hypothesized telomere length, a marker of cellular aging, would be longer in women who had 2-3 pregnancies. Leukocyte telomere length was measured using quantitative real-time polymerase chain reaction in 620 women in CARDIA at the year 15 and 20 exams, expressed as the ratio of telomere repeat copy number to single-copy gene copy number (T/S). Number of pregnancies at the time of telomere length measurement was obtained (mean age = 41±0.1 years, average gravidity = 2.64±0.1 pregnancies). Participants were divided into 4 groups by number of pregnancies: 0, 1, 2-3, and ≥4, to test for differences in telomere length by gravidity group. The mean and SD for telomere length was 0.98 ± 0.20 T/S in the whole cohort. There were no differences in mean telomere length between groups; 0.98±0.02 T/S in women with 0 pregnancies, 1.01±0.02 T/S in women with 1 pregnancy, 0.97±0.01 T/S in women with 2-3 pregnancies, and 0.99±0.02 T/S in women with ≥4 pregnancies (p = 0.51). We defined high-risk (shorter) telomere length as ≤25th percentile, and low-risk (longer) telomere length as ≥75 percentile. There were no differences in the prevalence of high-risk or low-risk telomere length between gravidity groups. Gravidity was not associated with telomere length in early middle age; the protective association of 2-3 births may act through other mechanisms.

Application of a tri-axial accelerometry-based portable motion recorder for the quantitative assessment of hippotherapy in children and adolescents with cerebral palsy

PubMed Central

Mutoh, Tomoko; Mutoh, Tatsushi; Takada, Makoto; Doumura, Misato; Ihara, Masayo; Taki, Yasuyuki; Tsubone, Hirokazu; Ihara, Masahiro

2016-01-01

[Purpose] This case series aims to evaluate the effects of hippotherapy on gait and balance ability of children and adolescents with cerebral palsy using quantitative parameters for physical activity. [Subjects and Methods] Three patients with gait disability as a sequela of cerebral palsy (one female and two males; age 5, 12, and 25 years old) were recruited. Participants received hippotherapy for 30 min once a week for 2 years. Gait parameters (step rate, step length, gait speed, mean acceleration, and horizontal/vertical displacement ratio) were measured using a portable motion recorder equipped with a tri-axial accelerometer attached to the waist before and after a 10-m walking test. [Results] There was a significant increase in step length between before and after a single hippotherapy session. Over the course of 2 year intervention, there was a significant increase in step rate, gait speed, step length, and mean acceleration and a significant improvement in horizontal/vertical displacement ratio. [Conclusion] The data suggest that quantitative parameters derived from a portable motion recorder can track both immediate and long-term changes in the walking ability of children and adolescents with cerebral palsy undergoing hippotherapy. PMID:27821971

[Growth standardized values and curves based on weight, length/height and head circumference for Chinese children under 7 years of age].

PubMed

Li, Hui

2009-03-01

To construct the growth standardized data and curves based on weight, length/height, head circumference for Chinese children under 7 years of age. Random cluster sampling was used. The fourth national growth survey of children under 7 years in the nine cities (Beijing, Harbin, Xi'an, Shanghai, Nanjing, Wuhan, Fuzhou, Guangzhou and Kunming) of China was performed in 2005 and from this survey, data of 69 760 urban healthy boys and girls were used to set up the database for weight-for-age, height-for-age (length was measured for children under 3 years) and head circumference-for-age. Anthropometric data were ascribed to rigorous methods of data collection and standardized procedures across study sites. LMS method based on BOX-COX normal transformation and cubic splines smoothing technique was chosen for fitting the raw data according to study design and data features, and standardized values of any percentile and standard deviation were obtained by the special formulation of L, M and S parameters. Length-for-age and height-for-age standards were constructed by fitting the same model but the final curves reflected the 0.7 cm average difference between these two measurements. A set of systematic diagnostic tools was used to detect possible biases in estimated percentiles or standard deviation curves, including chi2 test, which was used for reference to evaluate to the goodness of fit. The 3rd, 10th, 25th, 50th, 75th, 90th, 97th smoothed percentiles and -3, -2, -1, 0, +1, +2, +3 SD values and curves of weight-for-age, length/height-for-age and head circumference-for-age for boys and girls aged 0-7 years were made out respectively. The Chinese child growth charts was slightly higher than the WHO child growth standards. The newly established growth charts represented the growth level of healthy and well-nourished Chinese children. The sample size was very large and national, the data were high-quality and the smoothing method was internationally accepted. The new Chinese

Semi-rigid screws provide an auxiliary option to plate working length to control interfragmentary movement in locking plate fixation at the distal femur.

PubMed

Heyland, Mark; Duda, Georg N; Haas, Norbert P; Trepczynski, Adam; Döbele, Stefan; Höntzsch, Dankward; Schaser, Klaus-Dieter; Märdian, Sven

2015-10-01

Extent and orientation of interfragmentary movement (IFM) are crucially affecting course and quality of fracture healing. The effect of different configurations for implant fixation on successful fracture healing remain unclear. We hypothesize that screw type and configuration of locking plate fixation profoundly influences stiffness and IFM for a given load in a distal femur fracture model. Simple analytical models are presented to elucidate the influence of fixation configuration on construct stiffness. Models were refined with a consistent single-patient-data-set to create finite-element femur models. Locking plate fixation of a distal femoral 10mm-osteotomy (comminution model) was fitted with rigid locking screws (rLS) or semi-rigid locking screws (sLS). Systematic variations of screw placements in the proximal fragment were tested. IFM was quantitatively assessed and compared for different screw placements and screw types. Different screw allocations significantly affect IFM in a locking plate construct. LS placement of the first screw proximal to the fracture (plate working length, PWL) has a significant effect on axial IFM (p < 0.001). Replacing rLS with sLS caused an increase (p < 0.001) of IFM under the plate (cis-cortex) between +8.4% and +28.1% for the tested configurations but remained constant medially (<1.1%, trans-cortex). Resultant shear movements markedly increased at fracture level (p < 0.001) to the extent that plate working length increased. The ratio of shear/axial IFM was found to enhance for longer PWL. sLS versus rLS lead to significantly smaller ratios of shear/axial IFM at the cis-cortex for PWL of ≥ 62 mm (p ≤ 0.003). Mechanical frame conditions can be significantly influenced by type and placement of the screws in locking plate osteosynthesis of the distal femur. By varying plate working length stiffness and IFM are modulated. Moderate axial and concomitantly low shear IFM could not be achieved through changes in screw placement

High temperature co-axial winding transformers

NASA Technical Reports Server (NTRS)

Divan, Deepakraj M.; Novotny, Donald W.

1993-01-01

The analysis and design of co-axial winding transformers is presented. The design equations are derived and the different design approaches are discussed. One of the most important features of co-axial winding transformers is the fact that the leakage inductance is well controlled and can be made low. This is not the case in conventional winding transformers. In addition, the power density of co-axial winding transformers is higher than conventional ones. Hence, using co-axial winding transformers in a certain converter topology improves the power density of the converter. The design methodology used in meeting the proposed specifications of the co-axial winding transformer specifications are presented and discussed. The final transformer design was constructed in the lab. Co-axial winding transformers proved to be a good choice for high power density and high frequency applications. They have a more predictable performance compared with conventional transformers. In addition, the leakage inductance of the transformer can be controlled easily to suit a specific application. For space applications, one major concern is the extraction of heat from power apparatus to prevent excessive heating and hence damaging of these units. Because of the vacuum environment, the only way to extract heat is by using a cold plate. One advantage of co-axial winding transformers is that the surface area available to extract heat from is very large compared to conventional transformers. This stems from the unique structure of the co-axial transformer where the whole core surface area is exposed and can be utilized for cooling effectively. This is a crucial issue here since most of the losses are core losses.

Evaluation of axial pile bearing capacity based on pile driving analyzer (PDA) test using Neural Network

NASA Astrophysics Data System (ADS)

Maizir, H.; Suryanita, R.

2018-01-01

A few decades, many methods have been developed to predict and evaluate the bearing capacity of driven piles. The problem of the predicting and assessing the bearing capacity of the pile is very complicated and not yet established, different soil testing and evaluation produce a widely different solution. However, the most important thing is to determine methods used to predict and evaluate the bearing capacity of the pile to the required degree of accuracy and consistency value. Accurate prediction and evaluation of axial bearing capacity depend on some variables, such as the type of soil, diameter, and length of pile, etc. The aims of the study of Artificial Neural Networks (ANNs) are utilized to obtain more accurate and consistent axial bearing capacity of a driven pile. ANNs can be described as mapping an input to the target output data. The method using the ANN model developed to predict and evaluate the axial bearing capacity of the pile based on the pile driving analyzer (PDA) test data for more than 200 selected data. The results of the predictions obtained by the ANN model and the PDA test were then compared. This research as the neural network models give a right prediction and evaluation of the axial bearing capacity of piles using neural networks.

Reduced vision in highly myopic eyes without ocular pathology: the ZOC-BHVI high myopia study.

PubMed

Jong, Monica; Sankaridurg, Padmaja; Li, Wayne; Resnikoff, Serge; Naidoo, Kovin; He, Mingguang

2018-01-01

The aim was to investigate the relationship of the magnitude of myopia with visual acuity in highly myopic eyes without ocular pathology. Twelve hundred and ninety-two highly myopic eyes (up to -6.00 DS both eyes, no astigmatic cut-off) with no ocular pathology from the ZOC-BHVI high myopia study in China, had cycloplegic refraction, followed by subjective refraction and visual acuities and axial length measurement. Two logistic regression models were undertaken to test the association of age, gender, refractive error, axial length and parental myopia with reduced vision. Mean group age was 19.0 ± 8.6 years; subjective spherical equivalent refractive error was -9.03 ± 2.73 D; objective spherical equivalent refractive error was -8.90 ± 2.60 D and axial length was 27.0 ± 1.3 mm. Using visual acuity, 82.4 per cent had normal vision, 16.0 per cent had mildly reduced vision, 1.2 per cent had moderately reduced vision, 0.3 per cent had severely reduced vision and no subjects were blind. The percentage with reduced vision increased with spherical equivalent to 74.5 per cent from -15.00 to -39.99 D, axial length to 67.7 per cent of eyes from 30.01 to 32.00 mm and age to 22.9 per cent of those 41 years and over. Spherical equivalent and axial length were significantly associated with reduced vision (p < 0.0001). Age and parental myopia were not significantly associated with reduced vision. Gender was significant for one model (p = 0.04). Mildly reduced vision is common in high myopia without ocular pathology and is strongly correlated with greater magnitudes of refractive error and axial length. Better understanding is required to minimise reduced vision in high myopes. © 2017 Optometry Australia.

Influence of Gender and Age on Upper-Airway Length During Development

PubMed Central

Ronen, Ohad; Malhotra, Atul; Pillar, Giora

2008-01-01

OBJECTIVE Obstructive sleep apnea has a strong male predominance in adults but not in children. The collapsible portion of the upper airway is longer in adult men than in women (a property that may increase vulnerability to collapse during sleep). We sought to test the hypothesis that in prepubertal children, pharyngeal airway length is equal between genders, but after puberty boys have a longer upper airway than girls, thus potentially contributing to this change in apnea propensity. METHODS Sixty-nine healthy boys and girls who had undergone computed tomography scans of their neck for other reasons were selected from the computed tomography archives of Rambam and Carmel hospitals. The airway length was measured in the midsagittal plane and defined as the length between the lower part of the posterior hard palate and the upper limit of the hyoid bone. Airway length and normalized airway length/body height were compared between the genders in prepubertal (4- to 10-year-old) and postpubertal (14- to 19-year-old) children. RESULTS In prepubertal children, airway length was similar between boys and girls (43.2 ± 5.9 vs 46.8 ± 7.7 mm, respectively). When normalized to body height, airway length/body height was significantly shorter in prepubertal boys than in girls (0.35 ± 0.03 vs 0.38 ± 0.04 mm/cm). In contrast, postpubertal boys had longer upper airways (66.5 ± 9.2 vs 52.2 ± 7.0 mm) and normalized airway length/body height (0.38 ± 0.05 vs 0.33 ± 0.05 mm/cm) than girls. CONCLUSIONS Although boys have equal or shorter airway length compared with girls among prepubertal children, after puberty, airway length and airway length normalized for body height are significantly greater in boys than in girls. These data suggest that important anatomic changes at puberty occur in a gender-specific manner, which may be important in explaining the male predisposition to pharyngeal collapse in adults. PMID:17908723

Polestriding Intervention Improves Gait and Axial Symptoms in Mild to Moderate Parkinson Disease.

PubMed

Krishnamurthi, Narayanan; Shill, Holly; O'Donnell, Darolyn; Mahant, Padma; Samanta, Johan; Lieberman, Abraham; Abbas, James

2017-04-01

To evaluate the effects of 12-week polestriding intervention on gait and disease severity in people with mild to moderate Parkinson disease (PD). A-B-A withdrawal study design. Outpatient movement disorder center and community facility. Individuals (N=17; 9 women [53%] and 8 men [47%]; mean age, 63.7±4.9y; range, 53-72y) with mild to moderate PD according to United Kingdom brain bank criteria with Hoehn & Yahr score ranging from 2.5 to 3.0 with a stable medication regimen and ability to tolerate "off" medication state. Twelve-week polestriding intervention with 12-week follow-up. Gait was evaluated using several quantitative temporal, spatial, and variability measures. In addition, disease severity was assessed using clinical scales such as Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn & Yahr scale, and Parkinson's Disease Questionnaire-39. Step and stride lengths, gait speed, and step-time variability were improved significantly (P<.05) because of 12-week polestriding intervention. Also, the UPDRS motor score, the UPDRS axial score, and the scores of UPDRS subscales on walking and balance improved significantly after the intervention. Because increased step-time variability and decreased step and stride lengths are associated with PD severity and an increased risk of falls in PD, the observed improvements suggest that regular practice of polestriding may reduce the risk of falls and improve mobility in people with PD. Copyright © 2016 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Flow Split Venturi, Axially-Rotated Valve

DOEpatents

Walrath, David E.; Lindberg, William R.; Burgess, Robert K.; LaBelle, James

2000-02-22

The present invention provides an axially-rotated valve which permits increased flow rates and lower pressure drop (characterized by a lower loss coefficient) by using an axial eccentric split venturi with two portions where at least one portion is rotatable with respect to the other portion. The axially-rotated valve typically may be designed to avoid flow separation and/or cavitation at full flow under a variety of conditions. Similarly, the valve is designed, in some embodiments, to produce streamlined flow within the valve. An axially aligned outlet may also increase the flow efficiency. A typical cross section of the eccentric split venturi may be non-axisymmetric such as a semicircular cross section which may assist in both throttling capabilities and in maximum flow capacity using the design of the present invention. Such a design can include applications for freeze resistant axially-rotated valves and may be fully-opened and fully-closed in one-half of a complete rotation. An internal wide radius elbow typically connected to a rotatable portion of the eccentric venturi may assist in directing flow with lower friction losses. A valve actuator may actuate in an axial manner yet be uniquely located outside of the axial flow path to further reduce friction losses. A seal may be used between the two portions that may include a peripheral and diametrical seal in the same plane. A seal separator may increase the useful life of the seal between the fixed and rotatable portions.

Axial hypertonicity in Parkinson’s disease: Direct measurements of trunk and hip torque

PubMed Central

Wright, W.G.; Gurfinkel, V.S.; Nutt, J.; Horak, F.B.; Cordo, P.J.

2007-01-01

A cardinal feature of Parkinson’s disease (PD) is muscle hypertonicity, i.e. rigidity. Little is known about the axial tone in PD or the relation of hypertonia to functional impairment. We quantified axial rigidity to assess its relation to motor symptoms as measured by UPDRS and determine whether rigidity is affected by levodopa treatment. Axial rigidity was measured in 12 PD and 14 age-matched controls by directly measuring torsional resistance of the longitudinal axis to twisting (±10°). Feet were rotated relative to fixed hips (Hip Tone) or feet and hips were rotated relative to fixed shoulders (Trunk Tone). To assess tonic activity only, low constant velocity rotation (1°/s) and low acceleration (<12°/s2) were used to avoid eliciting phasic sensorimotor responses. Subjects stood during testing without changing body orientation relative to gravity. Body parts fixed against rotation could translate laterally within the boundaries of normal postural sway, but could not rotate. PD OFF-medication had higher axial rigidity (p<0.05) in hips (5.07 Nm) and trunk (5.30 Nm) than controls (3.51 Nm and 4.46 Nm, respectively), which didn’t change with levodopa (p>0.10). Hip-to-trunk torque ratio was greater in PD than controls (p<0.05) and unchanged by levodopa (p=0.28). UPDRS scores were significantly correlated with hip rigidity for PD OFF-medication (r=0.73, p<0.05). Torsional resistance to clockwise versus counter-clockwise axial rotation was more asymmetrical in PD than controls (p<0.05), however, there was no correspondence between direction of axial asymmetry and side of disease onset. In conclusion, these findings concerning hypertonicity may underlie functional impairments of posture and locomotion in PD. The absence of a levodopa effect on axial tone suggests axial and appendicular tone are controlled by separate neural circuits. PMID:17692315

Gestational Age at Birth and Brain White Matter Development in Term-Born Infants and Children.

PubMed

Ou, X; Glasier, C M; Ramakrishnaiah, R H; Kanfi, A; Rowell, A C; Pivik, R T; Andres, A; Cleves, M A; Badger, T M

2017-12-01

Studies on infants and children born preterm have shown that adequate gestational length is critical for brain white matter development. Less is known regarding how variations in gestational age at birth in term infants and children affect white matter development, which was evaluated in this study. Using DTI tract-based spatial statistics methods, we evaluated white matter microstructures in 2 groups of term-born (≥37 weeks of gestation) healthy subjects: 2-week-old infants ( n = 44) and 8-year-old children ( n = 63). DTI parameters including fractional anisotropy, mean diffusivity, axial diffusivity, and radial diffusivity were calculated by voxelwise and ROI methods and were correlated with gestational age at birth, with potential confounding factors such as postnatal age and sex controlled. Fractional anisotropy values, which are markers for white matter microstructural integrity, positively correlated ( P < .05, corrected) with gestational age at birth in most major white matter tracts/regions for the term infants. Mean diffusivity values, which are measures of water diffusivities in the brain, and axial and radial diffusivity values, which are markers for axonal growth and myelination, respectively, negatively correlated ( P < .05, corrected) with gestational age at birth in all major white matter tracts/regions excluding the body and splenium of the corpus callosum for the term infants. No significant correlations with gestational age were observed for any tracts/regions for the term-born 8-year-old children. Our results indicate that longer gestation during the normal term period is associated with significantly greater infant white matter development (as reflected by higher fractional anisotropy and lower mean diffusivity, axial diffusivity, and radial diffusivity values); however, similar associations were not observable in later childhood. © 2017 by American Journal of Neuroradiology.

Age of onset of myopia predicts risk of high myopia in later childhood in myopic Singapore children.

PubMed

Chua, Sharon Y L; Sabanayagam, Charumathi; Cheung, Yin-Bun; Chia, Audrey; Valenzuela, Robert K; Tan, Donald; Wong, Tien-Yin; Cheng, Ching-Yu; Saw, Seang-Mei

2016-07-01

To investigate the effect of age of myopia onset on the severity of myopia later in life among myopic children. In this prospective study, school children aged 7-9 years from the Singapore Cohort Of the Risk factors for Myopia (SCORM) were followed up till 11 years (n = 928). Age of myopia onset was defined either through questionnaire at baseline (age 7-9 years) or subsequent annual follow-up visits. Age of onset of myopia was a surrogate indicator of duration of myopia progression till age 11 years. Cycloplegic refraction and axial length were measured at every annual eye examination. High myopia was defined as spherical equivalent of ≤-5.0 D. A questionnaire determined the other risk factors. In multivariable regression models, younger age of myopia onset (per year decrease) or longer duration of myopia progression was associated with high myopia (odds ratio (OR) = 2.86; 95% CI: 2.39 to 3.43), more myopic spherical equivalent (regression coefficient (β) = -0.86 D; 95% CI: -0.93 to -0.80) and longer axial length (β = 0.28 mm; 95% CI: 0.24 to 0.32) at aged 11 years, after adjusting for gender, race, school, books per week and parental myopia. In Receiver Operating Curve (ROC) analyses, age of myopia onset alone predicted high myopia by 85% (area under the curve = 0.85), while the addition of other factors including gender, race, school, books per week and parental myopia only marginally improved this prediction (area under the curve = 0.87). Age of myopia onset or duration of myopia progression was the most important predictor of high myopia in later childhood in myopic children. Future trials to retard the progression of myopia to high myopia could focus on children with younger age of myopia onset or with longer duration of myopia progression. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

The relationships between chronological age, length of experience, and job performance ratings of air route traffic control specialists.

DOT National Transportation Integrated Search

1967-06-01

The survey-type study of several hundred journeymen radar control specialists of four Air Route Traffic Control Centers was conducted in order to determine the extent to which job performance might be associative with chronological age and length of ...

A Mini Axial and a Permanent Maglev Radial Heart Pump§

PubMed Central

Qian, Kun-Xi; Ru, Wei-Min; Wang, Hao; Jing, Teng

2007-01-01

The implantability and durability have been for decades the focus of artificial heart R&D. A mini axial and a maglev radial pump have been developed to meet with such requirements. The mini axial pump weighing 27g (incl.5g rotor) has an outer diameter of 21mm and a length of 10mm in its largest point, but can produce a maximal blood flow of 6l/min with 50mmHg pressure increase. Therefore, it is suitable for the patients of 40-60kg body weight. For other patients of 60-80kg or 80-100kg body weight, the mini axial pumps of 23mm and 25mm outer diameter had been developed before, these devices were acknowledged to be the world smallest LVADs by Guinness World Record Center in 2004. The permanent maglev radial pump weighing 150g is a shaft-less centrifugal pump with permanent magnetic bearings developed by the author. It needs no second coil for suspension of the rotor except the motor coil, different from all other maglev pumps developed in USA, Japan, European, etc. Thus no detecting and controlling systems as well as no additional power supply for maglev are necessary. The pump can produce a blood flow up to as large as 10l/min against 100mmHg pressure. An implantable and durable blood pump will be a viable alternative to natural donor heart for transplantation. PMID:19662120

An Axial-Torsional, Thermomechanical Fatigue Testing Technique

NASA Technical Reports Server (NTRS)

Kalluri, Sreeramesh; Bonacuse, Peter J.

1995-01-01

A technique for conducting strain-controlled, thermomechanical, axial-torsional fatigue tests on thin-walled tubular specimens was developed. Three waveforms of loading, namely, the axial strain waveform, the engineering shear strain waveform, and the temperature waveform were required in these tests. The phasing relationships between the mechanical strain waveforms and the temperature and axial strain waveforms were used to define a set of four axial-torsional, thermomechanical fatigue (AT-TMF) tests. Real-time test control (3 channels) and data acquisition (a minimum of 7 channels) were performed with a software program written in C language and executed on a personal computer. The AT-TMF testing technique was used to investigate the axial-torsional thermomechanical fatigue behavior of a cobalt-base superalloy, Haynes 188. The maximum and minimum temperatures selected for the AT-TMF tests were 760 and 316 C, respectively. Details of the testing system, calibration of the dynamic temperature profile of the thin-walled tubular specimen, thermal strain compensation technique, and test control and data acquisition schemes, are reported. The isothermal, axial, torsional, and in- and out-of-phase axial-torsional fatigue behaviors of Haynes 188 at 316 and 760 C were characterized in previous investigations. The cyclic deformation and fatigue behaviors of Haynes 188 in AT-TMF tests are compared to the previously reported isothermal axial-torsional behavior of this superalloy at the maximum and minimum temperatures.

Longitudinal patterns in flathead catfish relative abundance and length at age within a large river: Effects of an urban gradient

USGS Publications Warehouse

Paukert, C.P.; Makinster, A.S.

2009-01-01

We investigated the spatial variation of flathead catfish (Pylodictis olivaris) relative abundance and growth in the 274 km long Kansas River to determine if population dynamics of catfish are related to urbanization. Electrofishing was conducted at 462 random sites throughout the river in summer, 2005-2006 to collect fish. Relative abundance of age 1 fish (???200mm), subadult (>200-400mm) and adult fish (>400 mm) ranged from 0.34 to 14.67 fish h-1, mean length at age 1 was 165 (range: 128-195) mm total length (TL) and mean length at age 3 was 376 mm TL (range: 293-419mm TL). The proportion of land use within 200 m of the river edge was between 0 and 0.54 urban. River reaches with high relative abundance of age 1 flathead catfish had high relative abundance of subadult and adult catfish. River reaches with fast flathead catfish growth to age 1 had fast growth to age 3. High urban land use and riprap in the riparian area were evident in river reaches near the heavily populated Kansas City and Topeka, Kansas, USA. Reaches with increased number of log jams and islands had decreased riparian agriculture. Areas of low urbanization had faster flathead catfish growth (r = 0.67, p = 0.005). Relative abundance of flathead catfish was higher in more agricultural areas (r = -0.57, p = 0.02). Changes in land use in riverine environments may alter population dynamics of a fish species within a river. Spatial differences in population dynamics need to be considered when evaluating riverine fish populations. Published in 2008 by John Wiley & Sons Ltd.

Axial Flow Conditioning Device for Mitigating Instabilities

NASA Technical Reports Server (NTRS)

Ahuja, Vineet (Inventor); Birkbeck, Roger M. (Inventor); Hosangadi, Ashvin (Inventor)

2017-01-01

A flow conditioning device for incrementally stepping down pressure within a piping system is presented. The invention includes an outer annular housing, a center element, and at least one intermediate annular element. The outer annular housing includes an inlet end attachable to an inlet pipe and an outlet end attachable to an outlet pipe. The outer annular housing and the intermediate annular element(s) are concentrically disposed about the center element. The intermediate annular element(s) separates an axial flow within the outer annular housing into at least two axial flow paths. Each axial flow path includes at least two annular extensions that alternately and locally direct the axial flow radially outward and inward or radially inward and outward thereby inducing a pressure loss or a pressure gradient within the axial flow. The pressure within the axial flow paths is lower than the pressure at the inlet end and greater than the vapor pressure for the axial flow. The invention minimizes fluidic instabilities, pressure pulses, vortex formation and shedding, and/or cavitation during pressure step down to yield a stabilized flow within a piping system.

Choroidal thickness measurement in children using optical coherence tomography.

PubMed

Bidaut-Garnier, Mélanie; Schwartz, Claire; Puyraveau, Marc; Montard, Michel; Delbosc, Bernard; Saleh, Maher

2014-04-01

To measure choroidal thickness (CT) in children of various ages by using spectral optical coherence tomography with enhanced depth imaging and to investigate the association between subfoveal CT and ocular axial length, age, gender, weight, and height in children. Healthy children were prospectively included between May and August 2012. Optical coherence tomography with the enhanced depth imaging system (Spectralis, Heidelberg, Germany) was used for choroidal imaging at nine defined points of the macula of both eyes. Axial length was measured using IOLMaster (Carl Zeiss Meditec, Dublin, CA). Height, weight, and refraction were recorded. Interobserver agreement in readings was also assessed by the Bland-Altman Method. Three hundred and forty-eight eyes from 174 children aged 3.5 years to 14.9 years were imaged. The mean subfoveal CT in right eyes was 341.96 ± 74.7 µm. Choroidal thickness increased with age (r = 0.24, P = 0.017), height, and weight but not with gender (P > 0.05). It was also inversely correlated to the axial length (r = 0.24, P = 0.001). The nasal choroid appeared thinner than in the temporal area (analysis of variance, P < 0.0001). In children, CT increases with age and is inversely correlated to axial length. There is a significant variation of CT between children of the same age.

Determinants of Major League Baseball Pitchers' Career Length.

PubMed

Hardy, Rich; Ajibewa, Tiwaloluwa; Bowman, Ray; Brand, Jefferson C

2017-02-01

To investigate variables (injury, position, performance, and pitching volume) that affect the career longevity of Major League Baseball pitchers. To be eligible, pitchers must have entered Major League Baseball between 1989 and 1992 without missing information for the variables on the website http://www.baseball-reference.com. The variables assessed were average innings pitched per year before and after age 25 years, earned run average, walks and hits divided by innings pitched, strikeout to walk ratio, pitching position, time on the disabled list, length of career, and starting and retirement age. We used analysis of variance to compare the differences between groups and a regression model to assess the relationship between variables before age 25 years and career length. Mean retirement age for the group was 31.74 (95% confidence interval 30.83-32.65) and mean career length was 10.97 (95% confidence interval, 10.02-11.92) years. Innings pitched after age 25 years increased slightly, but not significantly, from the number of innings pitched before age 25 years, 85.35 versus 74.25, P = .5063. Career earned run average was not significantly different after age 25 years compared with before age 25 years, 4.83 versus 5.58, respectively, P = .8834. Both strikeout to walk ratio, 1.55 to 1.77, P = .0022, and walks and hits divided by innings pitched, 1.63 to 1.50, P = .0339, improved significantly after age 25 years compared with before age 25 years. The position the player started and ended his career (starter or reliever) did not influence career length. Multiple regression analysis comparing the variables from before age 25 revealed only the number of innings pitched before age 25 were positively related to career length, R 2  = 0.1408, P < .0001. All other variables analyzed before age 25 years were not significantly related to career length. The only studied variable that had significant relationship, which was weak to low, with career length was

Reference charts of sitting height, leg length and body proportions for Chinese children aged 0-18 years.

PubMed

Zhang, Ya-qin; Li, Hui

2015-01-01

The reference charts of sitting height (SH), subischial leg length (LL) and the sitting height/leg length ratio (SH/LL) are useful tools in assessing body proportion for clinicians and researchers in related areas. However, reference charts of body proportions for Chinese children and adolescents are limited. To construct reference charts of SH, LL and SH/LL for Chinese children and adolescents. Stature and sitting height of 92 494 (46 240 boys and 46 254 girls) healthy Han nationality children, aged 0-18 years, were measured in two national large-scale cross-sectional surveys in 2005 in China. SH/LL was selected as the indicator of body proportion. References of SH, LL and SH/LL were constructed using the LMS method. The reference charts demonstrated that SH and LL increased with age. Growth in SH slowed by the age of 17 years in boys and 15 years in girls. Similarly, growth in LL slowed at 16 years in boys and 14 years in girls. The SH/LL ratio declined from birth (2.00 in boys and 2.03 in girls) to 13 years in boys (1.11) and to 11 years in girls (1.13), then increased slightly to the age of 18 (1.16 in boys and 1.18 in girls). The gender difference of SH/LL was not significantly different before the age of 11 years. After the age of 11, SH/LL appeared elevated in girls compared to boys. The reference charts of SH, LL and SH/LL are useful tools for assessing body proportions for Chinese children and adolescent individuals.

Effects of Birth Weight on Anterior Segment Measurements in Full-Term Children Without Low Birth Weight by Dual-Scheimpflug Analyzer.

PubMed

Yeter, Volkan; Aritürk, Nurşen; Bİrİncİ, Hakki; Süllü, Yüksel; Güngör, İncİ

2015-10-01

To evaluate the effects of birth weight on ocular anterior segment parameters in full-term children without low birth weight using the Galilei Dual-Scheimpflug Analyzer. Retrospective cohort study. The right eyes from 110 healthy children, 3-6 years of age, were scanned with the Galilei Dual-Scheimpflug Analyzer. A total of 78 eyes were measured in full-term children with birth weight of >2500 g. Central, paracentral, pericentral, and the thinnest corneal thicknesses; anterior and posterior keratometry (average, steep, flat); axial curvatures; asphericity of cornea; anterior chamber depth and volume; and iridocorneal angle values were measured. Axial length, lens thickness, and vitreous length were obtained by ultrasound biometry. The mean age of children was 55.86 ± 12.52 (mean ± SD) months. Mean birth weight and gestational age were 3426.3 ± 545 g and 39.4 ± 1.2 weeks, respectively. Although lens thickness, vitreous length, axial length, and anterior chamber volume were moderately correlated with birth weight (P < .05), there was no relationship between birth weight and anterior chamber depth. With the exception of pericentral corneal thickness, all regions of corneal thicknesses were correlated with birth weight (P < .05). Birth weight was negatively correlated with anterior curvature (P < .05) and had no relationship to posterior curvature. While central and paracentral axial curvatures correlated with birth weight (P < .05), pericentral axial curvature did not. Preschoolers who were born heavier had thicker cornea and lens, longer axial length, and flatter corneal curve. The thicknesses and axial curves of central cornea within 7 mm may be particularly associated with birth weight. Copyright © 2015 Elsevier Inc. All rights reserved.

Twin-Axial Wire Antenna

DTIC Science & Technology

2015-08-06

12 and 14 can be of differing gauges and can be either stranded or solid. In a prototype, both conductors were made from #22 solid copper wire ...08-2015 Publication Twin-Axial Wire Antenna David A. Tonn Naval Under Warfare Center Division, Newport 1176 Howell St., Code 00L, Bldg 102T...Approved for Public Release Distribution is unlimited Attorney Docket No. 300030 1 of 10 TWIN-AXIAL WIRE ANTENNA STATEMENT OF GOVERNMENT INTEREST

Mean-line Modeling of an Axial Turbine

NASA Astrophysics Data System (ADS)

Tkachenko, A. Yu; Ostapyuk, Ya A.; Filinov, E. P.

2018-01-01

The article describes the approach for axial turbine modeling along the mean line. It bases on the developed model of an axial turbine blade row. This model is suitable for both nozzle vanes and rotor blades simulations. Consequently, it allows the simulation of the single axial turbine stage as well as a multistage turbine. The turbine stage model can take into account the cooling air flow before and after a throat of each blade row, outlet straightener vanes existence and stagger angle controlling of nozzle vanes. The axial turbine estimation method includes the loss estimation and thermogasdynamic analysis. The single stage axial turbine was calculated with the developed model. The obtained results deviation was within 3% when comparing with the results of CFD modeling.

Axial gap rotating electrical machine

DOEpatents

None

2016-02-23

Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.

Axial Pump

NASA Technical Reports Server (NTRS)

Bozeman, Richard J., Jr. (Inventor); Akkerman, James W. (Inventor); Aber, Gregory S. (Inventor); VanDamm, George Arthur (Inventor); Bacak, James W. (Inventor); Svejkovsky, Paul A. (Inventor); Benkowski, Robert J. (Inventor)

1997-01-01

A rotary blood pump includes a pump housing for receiving a flow straightener, a rotor mounted on rotor bearings and having an inducer portion and an impeller portion, and a diffuser. The entrance angle, outlet angle, axial and radial clearances of blades associated with the flow straightener, inducer portion, impeller portion and diffuser are optimized to minimize hemolysis while maintaining pump efficiency. The rotor bearing includes a bearing chamber that is filled with cross-linked blood or other bio-compatible material. A back emf integrated circuit regulates rotor operation and a microcomputer may be used to control one or more back emf integrated circuits. A plurality of magnets are disposed in each of a plurality of impeller blades with a small air gap. A stator may be axially adjusted on the pump housing to absorb bearing load and maximize pump efficiency.

Comparison of axial length, anterior chamber depth and intraocular lens power between IOLMaster and ultrasound in normal, long and short eyes.

PubMed

Dong, Jing; Zhang, Yaqin; Zhang, Haining; Jia, Zhijie; Zhang, Suhua; Wang, Xiaogang

2018-01-01

To compare the axial length (AL), anterior chamber depth (ACD) and intraocular lens power (IOLP) of IOLMaster and Ultrasound in normal, long and short eyes. Seventy-four normal eyes (≥ 22 mm and ≤ 25 mm), 74 long eyes (> 25 mm) and 78 short eyes (< 22 mm) underwent AL and ACD measurements with both devices in the order of IOLMaster followed by Ultrasound. The IOLP were calculated using a free online LADAS IOL formula calculator. The difference in AL and IOLP between IOLMaster and Ultrasound was statistically significant when all three groups were combined. The difference in ACD between IOLMaster and Ultrasound was statistically significant in the normal group (P<0.001) and short eye group (P<0.001) but not the long eye group (P = 0.465). For the IOLP difference between IOLMaster and Ultrasound in the normal group, the percentage of IOLP differences <|0.5|D, ≥|0.5|D<|0.75|D, ≥|0.75|D<|1.0|D, and ≥|1.0|D were 90.5%, 8.1%, 1.4% and 0%, respectively. For the long eye group, they were 90.5%, 5.4%, 4.1% and 0%, respectively. For the short eye group, they were 61.5%, 23.1%, 10.3%, and 5.1%, respectively. IOLMaster and Ultrasound have statistically significant differences in AL measurements and IOLP (using LADAS formula) for normal, long eye and short eye. The two instruments agree regarding ACD measurements for the long eye group, but differ for the normal and short eye groups. Moreover, the high percentage of IOLP differences greater than |0.5|D in the short eye group is noteworthy.

Maternal telomere length inheritance in the king penguin.

PubMed

Reichert, S; Rojas, E R; Zahn, S; Robin, J-P; Criscuolo, F; Massemin, S

2015-01-01

Telomeres are emerging as a biomarker for ageing and survival, and are likely important in shaping life-history trade-offs. In particular, telomere length with which one starts in life has been linked to lifelong survival, suggesting that early telomere dynamics are somehow related to life-history trajectories. This result highlights the importance of determining the extent to which telomere length is inherited, as a crucial factor determining early life telomere length. Given the scarcity of species for which telomere length inheritance has been studied, it is pressing to assess the generality of telomere length inheritance patterns. Further, information on how this pattern changes over the course of growth in individuals living under natural conditions should provide some insight on the extent to which environmental constraints also shape telomere dynamics. To fill this gap partly, we followed telomere inheritance in a population of king penguins (Aptenodytes patagonicus). We tested for paternal and maternal influence on chick initial telomere length (10 days old after hatching), and how these relationships changed with chick age (at 70, 200 and 300 days old). Based on a correlative approach, offspring telomere length was positively associated with maternal telomere length early in life (at 10 days old). However, this relationship was not significant at older ages. These data suggest that telomere length in birds is maternally inherited. Nonetheless, the influence of environmental conditions during growth remained an important factor shaping telomere length, as the maternal link disappeared with chicks' age.

Referral patterns, diagnosis, and disease management of patients with axial spondyloarthritis: results of an international survey.

PubMed

van der Heijde, Désirée; Sieper, Joachim; Elewaut, Dirk; Deodhar, Atul; Pangan, Aileen L; Dorr, Alexander P

2014-12-01

Recognition, diagnosis, and management of axial spondyloarthritis (axial SpA) continue to advance. The objectives of this study were to compare referrals, diagnosis, and management of axial SpA in Western Europe (WE), North America (US and Canada), and the rest of world (RoW) in academic and community rheumatology practices and to identify areas for further education. Rheumatologists responded online to the MAXIMA (Management of Axial SpA International and Multicentric Approaches) survey. Questions pertained to referral, diagnosis, and management of axial SpA. Rheumatologists (N = 809) from 56 countries completed the survey about patients with chronic back pain (≥3 months) starting before age 45 years. Responses from academic and community practice rheumatologists were generally similar. Most referrals were from primary care providers. Symptom duration of 3 years or more at referral was reported more frequently by WE and RoW than US respondents. More WE and RoW than US rheumatologists referred to the Assessment of SpondyloArthritis International Society criteria for axial SpA in clinical practice. Rheumatologists reported prescribing disease-modifying antirheumatic drugs for the management of axial SpA. Sulfasalazine was frequently prescribed across regions; methotrexate was more commonly prescribed by US rheumatologists compared with other regions. Referral patterns, diagnosis, and disease management for axial SpA were similar among WE, North America, and RoW rheumatologists and in academic/community practices, although more WE and RoW rheumatologists referred to Assessment of SpondyloArthritis International Society criteria in clinical practice. Disease-modifying antirheumatic drugs were commonly prescribed for axial SpA patients, although it was unclear whether these were prescribed for axial or peripheral symptoms.

Rural–urban variations in age at menarche, adult height, leg-length and abdominal adiposity in black South African women in transitioning South Africa

PubMed Central

2018-01-01

Abstract Background: The pre-pubertal socioeconomic environment may be an important determinant of age at menarche, adult height, body proportions and adiposity: traits closely linked to adolescent and adult health. Aims: This study explored differences in age at menarche, adult height, relative leg-length and waist circumference between rural and urban black South African young adult women, who are at different stages of the nutrition and epidemiologic transitions. Subjects and methods: We compared 18–23 year-old black South African women, 482 urban-dwelling from Soweto and 509 from the rural Mpumalanga province. Age at menarche, obstetric history and household socio-demographic and economic information were recorded using interview-administered questionnaires. Height, sitting-height, hip and waist circumference were measured using standardised techniques. Results: Urban and rural black South African women differed in their age at menarche (at ages 12.7 and 14.5 years, respectively). In urban women, a one-year increase in age at menarche was associated with a 0.65 cm and 0.16% increase in height and relative leg-length ratio, respectively. In both settings, earlier age at menarche and shorter relative leg-length were independently associated with an increase in waist circumference. Conclusions: In black South African women, the earlier onset of puberty, and consequently an earlier growth cessation process, may lead to central fat mass accumulation in adulthood. PMID:29557678

What factors are associated with myopia in young adults? A survey study in Taiwan Military Conscripts.

PubMed

Lee, Yin-Yang; Lo, Chung-Ting; Sheu, Shwu-Jiuan; Lin, Julia L

2013-02-05

We investigated the independent impact of potential risk factors on myopia in young adults. A survey study was conducted with male military conscripts aged 18 to 24 years between February 2010 and March 2011 in Taiwan. The participants were examined using non-cycloplegic autorefraction and biometry. The participants provided data about potential risk factors, including age, parental myopia, education, near work, outdoor activity, and urbanization. Myopia was defined as the mean spherical equivalent of the right eye of ≤ 0.5 diopters (D). Among 5145 eligible participants, 5048 (98.11%) had refraction and questionnaire data available; 2316 (45.88%) of these received axial length examination. The prevalence of myopia was 86.1% with a mean refractive error of -3.66 D (SD = 2.73) and an axial length of 25.40 mm (SD = 1.38). Older age, having myopic parents, higher education level, more time spent reading, nearer reading distance, less outdoor activity, and higher urbanization level were associated with myopia and longer axial length. More computer use was related to longer axial length. All risk factors associated with myopia also were predictors of high myopia (≤ -6.0 D), with the exception of outdoor activity. Finally, an interaction analysis showed shorter axial length was associated with more time spent outdoors only at high urbanization level. Older age, parental myopia, higher education level, more near work, less outdoor activity, and higher urbanization level were independent predictors of myopia. These data provided evidence to the multifactorial nature of myopia in young men in Taiwan.

Interocular symmetry in macular choroidal thickness in children.

PubMed

Al-Haddad, Christiane; El Chaar, Lama; Antonios, Rafic; El-Dairi, Mays; Noureddin, Baha'

2014-01-01

Objective. To report interocular differences in choroidal thickness in children using spectral domain optical coherence tomography (SD-OCT) and correlate findings with biometric data. Methods. This observational cross-sectional study included 91 (182 eyes) healthy children aged 6 to 17 years with no ocular abnormality except refractive error. After a comprehensive eye exam and axial length measurement, high definition macular scans were performed using SD-OCT. Two observers manually measured the choroidal thickness at the foveal center and at 1500 µm nasally, temporally, inferiorly, and superiorly. Interocular differences were computed; correlations with age, gender, refractive error, and axial length were performed. Results. Mean age was 10.40 ± 3.17 years; mean axial length and refractive error values were similar between fellow eyes. There was excellent correlation between the two observers' measurements. No significant interocular differences were observed at any location. There was only a trend for right eyes to have higher values in all thicknesses, except the superior thickness. Most of the choroidal thickness measurements correlated positively with spherical equivalent but not with axial length, age, or gender. Conclusion. Choroidal thickness measurements in children as performed using SD-OCT revealed a high level of interobserver agreement and consistent interocular symmetry. Values correlated positively with spherical equivalent refraction.

Temporal and Spatial Variability in the Geochemistry of Axial and CoAxial Segment Lavas and their Mantle Sources

NASA Astrophysics Data System (ADS)

Smith, M. C.; Perfit, M. R.; Davis, C.; Kamenov, G. D.

2011-12-01

Three spatially related volcanic eruptions along the CoAxial Segment of the Juan de Fuca Ridge (JdFR) have documented emplacements between 1981 and 1993. Two of the historic flows outcrop at the "Flow Site" and were emplaced within less than 12 years and 500 m from one another. The third was emplaced at the "Floc Site" to the south in the 1980s. Previous studies have documented that CoAxial lavas are among the most incompatible element and isotopically depleted lavas along the entire JdFR, whereas the Axial Seamount segment immediately south of CoAxial has erupted the most chemically enriched lavas south of the Endeavor Segment. Geochemical studies have shown little temporal change in the chemistry of recent Axial Seamount eruptives, whereas CoAxial lavas exhibit distinct chemical differences over short time periods. Significant chemical differences observed among depleted CoAxial lavas emplaced close to one another in space and time are in marked contrast to the relatively constant chemical characteristics of enriched lavas erupted at the magmatically more robust Axial segment only 10's of kilometers to the south and west. New trace element and isotopic (Sr, Nd, Pb) geochemical analyses of historic and older CoAxial lavas have resulted in better documentation of interflow and intraflow chemical variation providing an improved understanding of spatial/temporal chemical variability in lavas, and further insight into JdFR magmatic processes. Modeling of major and trace element abundances suggest that the observed intraflow chemical variation within CoAxial lavas is largely due to shallow-level fractional crystallization but that a single fractional crystallization model cannot account for all interflow chemical variation. In fact, elemental and isotopic data require different parental magmas for each of the three recent CoAxial Segment lava flows suggesting very short-term differences or changes in the chemical character of the mantle source region. In particular

Study of axial magnetic effect

DOE Office of Scientific and Technical Information (OSTI.GOV)

Braguta, Victor; School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922; Chernodub, M. N.

2016-01-22

The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower comparedmore » to a theoretical prediction.« less

Effective Cross Section of Cold Formed Steel Column Under Axial Compression

NASA Astrophysics Data System (ADS)

Manikandan, P.; Pradeep, T.

2018-06-01

The compressive resistance of cold-formed steel (CFS) section may be governed by local, distortional or overall buckling and any apparent interaction between these modes. A new inventive stiffened CFS section is elected in this study, selected cross sections geometries and lengths are chosen such that all the types of buckling modes are met with. Buckling plot is plotted using linear elastic buckling analysis software (CUFSM). Using the test results obtained in the literature, the developed finite element model is calibrated and furthers a total of 126 parametric study is conducted such as a consequence of dimensions and the length of the cross section, thickness and yield stress. The FEA included relevant material and geometric imperfections. All the columns are analyzed under pin end conditions with axial compression. The analysis results demonstrate that the DSM equations generally assess the strength of stiffened section conservatively. Modifications to the DSM equations are recommended to evaluate the strength of stiffened section more precisely.

Comparative Investigation and Operational Performance Characteristics of a Wick Assisted and Axially Square Grooved Heat Pipe

NASA Astrophysics Data System (ADS)

Naik, Rudra, Dr.; Rama Narasihma, K., Dr.; Anikivi, Atmanand

2018-04-01

The present work reported here involves the experimental investigation and performance evaluation of wick assisted and axially square grooved heat pipes of outer diameter 8mm, inner diameter 4mm with a length of 150mm.The objective of this work is to design, fabricate and test the heat pipes with and without an axial square groove for horizontal and gravity assisted conditions. The performance of the heat pipes was measured in terms of thermal resistance and heat transfer coefficients. In the present investigation four different working fluids were chosen namely acetone, ethanol, methanol and distilled water. Experiments were conducted by varying the heat load from 2 W to 10 W for different fill charge ratios in the range of 25% to 75% of evaporator volume for wick assisted heat pipe and 8 W to 18 W for axially square grooved heat pipe. From the experiments, it was found that there is a steady increase in temperature with the increase in heat input. The overall heat transfer coefficient was found to increase with the increase heat load for wick assisted heat pipe. In case of axially square grooved heat pipe, an attempt was made to experiment the heat pipe in different orientations. The maximum heat transfer coefficient of 7000 W/m2 °C is found for Acetone at 180° orientation.

Short Telomere Length is Associated with Aging, Central Obesity, Poor Sleep and Hypertension in Lebanese Individuals

PubMed Central

Zgheib, Nathalie K; Sleiman, Fatima; Nasreddine, Lara; Nasrallah, Mona; Nakhoul, Nancy; Isma’eel, Hussain; Tamim, Hani

2018-01-01

In Lebanon, data stemming from national cross-sectional surveys indicated significant increasing trends in the prevalence of cardiovascular diseases and associated behavioral and age-related risk factors. To our knowledge, no data are available on relative telomere length (RTL) as a potential biomarker for age-related diseases in a Lebanese population. The aim of this study was to evaluate whether there is an association between RTL and demographic characteristics, lifestyle habits and diseases in the Lebanese. This was a cross-sectional study of 497 Lebanese subjects. Peripheral blood RTL was measured by amplifying telomere and single copy gene using real-time PCR. Mean ± SD RTL was 1.42 ± 0.83, and it was categorized into 3 tertiles. Older age (P=0.002) and wider waist circumference (WC) (P=0.001) were statistically significantly associated with shorter RTL. Multinomial logistic regression showed that subjects who had some level of sleeping difficulty had a statistically significantly shorter RTL when compared to those with no sleeping difficulties at all [OR (95% CI): 2.01 (1.11-3.62) in the first RTL tertile]. Importantly, statistically significantly shorter RTL was found with every additional 10 cm of WC [OR (95% CI): 1.30 (1.11-1.52) for first RTL tertile]. In addition, and after performing the multivariate logistic regression and adjusting for “predictors” of RTL, the odds of having hypertension or being treated for hypertension were higher in patients who had shorter RTL: OR (95% CI): 2.45 (1.36-4.44) and 2.28 (1.22-4.26) in the first RTL tertiles respectively with a similar trend, though not statistically significant, in the second RTL tertiles. This is the first study in Lebanon to show an association between age, central obesity, poor sleep and hypertension and RTL. It is hoped that telomere length measurement be potentially used as a biomarker for biological age and age-related diseases and progression in the Lebanese. PMID:29392083

The Correlation between Angle Kappa and Ocular Biometry in Koreans

PubMed Central

Choi, Se Rang

2013-01-01

Purpose To investigate normative angle kappa data and to examine whether correlations exist between angle kappa and ocular biometric measurements (e.g., refractive error, axial length) and demographic features in Koreans. Methods Data from 436 eyes (213 males and 223 females) were analyzed in this study. The angle kappa was measured using Orbscan II. We used ocular biometric measurements, including refractive spherical equivalent, interpupillary distance and axial length, to investigate the correlations between angle kappa and ocular biometry. The IOL Master ver. 5.02 was used to obtain axial length. Results The mean patient age was 57.5 ± 12.0 years in males and 59.4 ± 12.4 years in females (p = 0.11). Angle kappa averaged 4.70 ± 2.70 degrees in men and 4.89 ± 2.14 degrees in women (p = 0.48). Axial length and spherical equivalent were correlated with angle kappa (r = -0.342 and r = 0.197, respectively). The correlation between axial length and spherical equivalent had a negative correlation (r = -0.540, p < 0.001). Conclusions Angle kappa increased with spherical equivalent and age. Thus, careful manipulation should be considered in older and hyperopic patients when planning refractive or strabismus surgery. PMID:24311927

Axial Halbach Magnetic Bearings

NASA Technical Reports Server (NTRS)

Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

2008-01-01

Axial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control.

The feasibility of bomb radiocarbon analysis to support an age-at-length relationship for red abalone, Haliotis rufescens Swainson in northern California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leaf, R T; Andrews, A H; Cailliet, G M

2009-01-07

Analysis of bomb generated radiocarbon ({sup 14}C) changes in a red abalone, Haliotis rufescens Swainson shell was used to investigate age-at-length relationships derived from data from a previous multi-year, multi-site tag-recapture study. Shell carbonate was extracted from four successive growth trajectory locations in a single shell with a length of 251 mm MSL. Extraction locations were based on VBGF predictions and chosen to span the initial rise of the {sup 14}C-bomb pulse that is known to have occurred in surface ocean waters during 1958 {+-} 1 y in the northeast Pacific. The close temporal correspondence of the red abalone samplemore » series to regional {Delta}{sup 14}C records demonstrated the utility of the technique for validating age-at-length relationships for the red abalone. The findings provided support for a mean VBGF derived age of 32 y (range 30 to 33 y) for the specimen; however, the analysis of {sup 14}C data indicated that the specimen could be older.« less

System Study for Axial Vane Engine Technology

NASA Technical Reports Server (NTRS)

Badley, Patrick R.; Smith, Michael R.; Gould, Cedric O.

2008-01-01

The purpose of this engine feasibility study was to determine the benefits that can be achieved by incorporating positive displacement axial vane compression and expansion stages into high bypass turbofan engines. These positive-displacement stages would replace some or all of the conventional compressor and turbine stages in the turbine engine, but not the fan. The study considered combustion occurring internal to an axial vane component (i.e., Diesel engine replacing the standard turbine engine combustor, burner, and turbine); and external continuous flow combustion with an axial vane compressor and an axial vane turbine replacing conventional compressor and turbine systems.

Analyzing Axial Stress and Deformation of Tubular for Steam Injection Process in Deviated Wells Based on the Varied (T, P) Fields

PubMed Central

Liu, Yunqiang; Xu, Jiuping; Wang, Shize; Qi, Bin

2013-01-01

The axial stress and deformation of high temperature high pressure deviated gas wells are studied. A new model is multiple nonlinear equation systems by comprehensive consideration of axial load of tubular string, internal and external fluid pressure, normal pressure between the tubular and well wall, and friction and viscous friction of fluid flowing. The varied temperature and pressure fields were researched by the coupled differential equations concerning mass, momentum, and energy equations instead of traditional methods. The axial load, the normal pressure, the friction, and four deformation lengths of tubular string are got ten by means of the dimensionless iterative interpolation algorithm. The basic data of the X Well, 1300 meters deep, are used for case history calculations. The results and some useful conclusions can provide technical reliability in the process of designing well testing in oil or gas wells. PMID:24163623

Cellular aging and restorative processes: subjective sleep quality and duration moderate the association between age and telomere length in a sample of middle-aged and older adults.

PubMed

Cribbet, Matthew R; Carlisle, McKenzie; Cawthon, Richard M; Uchino, Bert N; Williams, Paula G; Smith, Timothy W; Gunn, Heather E; Light, Kathleen C

2014-01-01

To examine whether subjective sleep quality and sleep duration moderate the association between age and telomere length (TL). Participants completed a demographic and sleep quality questionnaire, followed by a blood draw. Social Neuroscience Laboratory. One hundred fifty-four middle-aged to older adults (age 45-77 y) participated. Participants were excluded if they were on immunosuppressive treatment and/or had a disease with a clear immunologic (e.g., cancer) component. N/A. Subjective sleep quality and sleep duration were assessed using the Pittsburgh Sleep Quality Index (PSQI) and TL was determined using peripheral blood mononuclear cells (PBMCs). There was a significant first-order negative association between age and TL. Age was also negatively associated with the self-reported sleep quality item and sleep duration component of the PSQI. A significant age × self-reported sleep quality interaction revealed that age was more strongly related to TL among poor sleepers, and that good sleep quality attenuated the association between age and TL. Moreover, adequate subjective sleep duration among older adults (i.e. greater than 7 h per night) was associated with TL comparable to that in middle-aged adults, whereas sleep duration was unrelated to TL for the middle-aged adults in our study. The current study provides evidence for an association between sleep quality, sleep duration, and cellular aging. Among older adults, better subjective sleep quality was associated with the extent of cellular aging, suggesting that sleep duration and sleep quality may be added to a growing list of modifiable behaviors associated with the adverse effects of aging.

The Effect of Age, Accommodation and Refractive Error on the Adult Human Eye

PubMed Central

Richdale, Kathryn; Bullimore, Mark A.; Sinnott, Loraine T.; Zadnik, Karla

2015-01-01

Purpose To quantify changes in ocular dimensions associated with age, refractive error, and accommodative response, in vivo, in 30- to 50-year-old human subjects. Methods The right eyes of 91 adults were examined using ultrasonography, phakometry, keratometry, pachymetry, interferometry, anterior segment optical coherence tomography, and high resolution magnetic resonance imaging. Accommodation was measured subjectively with a push-up test and objectively using open-field autorefraction. Regression analyses were used to assess differences in ocular parameters with age, refractive error and accommodation. Results With age, crystalline lens thickness increased (0.03 mm/yr), anterior lens curvature steepened (0.11 mm/yr), anterior chamber depth decreased (0.02 mm/y) and lens equivalent refractive index decreased (0.001 /y) (all p < 0.01). With increasing myopia, there were significant increases in axial length (0.37 mm/D), vitreous chamber depth (0.34 mm/D), vitreous chamber height (0.09 mm/D) and ciliary muscle ring diameter (0.10 mm/D) (all p < 0.05). Increasing myopia was also associated with steepening of both the cornea (0.16 mm/D) and anterior lens surface (0.011 mm/D) (both p < 0.04). With accommodation, the ciliary muscle ring diameter decreased (0.08 mm/D), and the muscle thinned posteriorly (0.008 mm/D), allowing the lens to shorten equatorially (0.07 mm/D) and thicken axially (0.06 mm/D) (all p < 0.03). Conclusions Refractive error is significantly correlated with not only the axial dimensions, but the anterior equatorial dimension of the adult eye. Further testing and development of accommodating intraocular lenses should account for differences in patients’ preoperative refractive error. PMID:26703933

Age-dependent associations between telomere length and environmental conditions in roe deer.

PubMed

Wilbourn, Rachael V; Froy, Hannah; McManus, Marie-Christina; Cheynel, Louise; Gaillard, Jean-Michel; Gilot-Fromont, Emmanuelle; Regis, Corinne; Rey, Benjamin; Pellerin, Maryline; Lemaître, Jean-François; Nussey, Daniel H

2017-09-01

Telomere length (TL) represents a promising biomarker of overall physiological state and of past environmental experiences, which could help us understand the drivers of life-history variation in natural populations. A growing number of studies in birds suggest that environmental stress or poor environmental conditions are associated with shortened TL, but studies of such relationships in wild mammals are lacking. Here, we compare leucocyte TL from cross-sectional samples collected from two French populations of roe deer which experience different environmental conditions. We found that, as predicted, TL was shorter in the population experiencing poor environmental conditions but that this difference was only significant in older individuals and was independent of sex and body mass. Unexpectedly, the difference was underpinned by a significant increase in TL with age in the population experiencing good environmental conditions, while there was no detectable relationship with age in poor conditions. These results demonstrate both the environmental sensitivity and complexity of telomere dynamics in natural mammal populations, and highlight the importance of longitudinal data to disentangle the within- and among-individual processes that generate them. © 2017 The Authors.

Ocular Risk Factors for Age-related Macular Degeneration: The Los Angeles Latino Eye Study (LALES)

PubMed Central

Fraser-Bell, Samantha; Choudhury, Farzana; Klein, Ronald; Azen, Stanley; Varma, Rohit

2010-01-01

Purpose To assess the association of ocular factors and age-related macular degeneration (AMD) in Latinos. Design Population-based, cross-sectional study of 6357 self-identified Latinos aged 40 years and older. Methods Ophthalmic examination included subjective refraction, measurement of axial length, evaluation of iris color, Lens Opacities Classification System II (LOCS II) grading of cataracts, and stereoscopic macular photographs for AMD lesions. Generalized estimating equation analysis incorporated data from both eyes to estimate odds ratios adjusted for covariates. Results After controlling for confounders (age, gender and smoking), prior cataract surgery was associated with advanced AMD (OR: 2.8, 95% CI 1.0, 7.8), increased retinal pigment (OR: 1.6, 95% CI 1.0, 1.5) and retinal pigment epithelial depigmentation (OR: 2.2, 95% CI 1.1, 4.4). The presence of any lens opacity was associated with soft drusen (OR: 1.2; 95% CI 1.0, 1.5). Longer axial length (per mm) was associated with a decreased odds of soft drusen, increased retinal pigment, and geographic atrophy (GA) (ORs: 0.8 [95% CI 0.7, 0.9], 0.8 [95% CI 0.7, 0.9], 0.7 [95% CI 0.5, 0.9], respectively. Myopia was inversely associated with soft drusen (OR: 0.8; 95% CI 0.7, 1.0). Lighter colored irises were associated with GA (OR: 5.0; 95% CI 1.0, 25.3). Conclusions Cross-sectional associations of ocular factors such as cataract, cataract surgery, and refractive errors with early AMD lesions found in Latinos were consistent with those in whites. Additionally, prior cataract surgery was associated with advanced AMD. PMID:20138605

Telomere Length and the Risk of Atrial Fibrillation: Insights into the Role of Biological versus Chronological Aging

PubMed Central

Roberts, Jason D.; Dewland, Thomas A.; Longoria, James; Fitzpatrick, Annette L.; Ziv, Elad; Hu, Donglei; Lin, Jue; Glidden, David V.; Psaty, Bruce M.; Burchard, Esteban G.; Blackburn, Elizabeth H.; Olgin, Jeffrey E.; Heckbert, Susan R.; Marcus, Gregory M.

2014-01-01

Background Advanced age is the most important risk factor for atrial fibrillation (AF), however the mechanism remains unknown. Telomeres, regions of DNA that shorten with cell division, are considered reliable markers of biological aging. We sought to examine the association between leukocyte telomere length (LTL) and incident AF in a large population-based cohort using direct LTL measurements and genetic data. To further explore our findings, we compared atrial cell telomere length (ATL) and LTL in cardiac surgery patients. Methods and Results Mean LTL and the TERT rs2736100 single nucleotide polymorphism (SNP) were assessed as predictors of incident AF in the Cardiovascular Health Study (CHS). Among the surgical patients, within subject comparison of ATL versus LTL was assessed. Among 1639 CHS participants, we observed no relationship between mean LTL and incident AF prior to and after adjustment for potential confounders (adjusted hazard ratio [HR] 1.09; 95% CI: 0.92–1.29, p=0.299); chronologic age remained strongly associated with AF in the same model. No association was observed between the TERT rs2736100 SNP and incident AF (adjusted HR: 0.95; 95% CI: 0.88–1.04, p=0.265). In 35 cardiac surgery patients (26 with AF), ATL was longer than LTL (1.19 ± 0.20 versus 1.02 ± 0.25 [T/S ratio], p< 0.001), a finding that remained consistent within the AF subgroup. Conclusions Our study revealed no evidence of an association between LTL and incident AF and no evidence of relative atrial cell telomere shortening in AF. Chronological aging independent of biological markers of aging is the primary risk factor for AF. PMID:25381796

What has influenced patient health-care expenditures in Japan?: variables of age, death, length of stay, and medical care.

PubMed

Sato, Emi; Fushimi, Kiyohide

2009-07-01

This study considers variables related to health-care expenditures associated with aging and long-term hospitalization in Japan. We focused on daily per capita inpatient health-care expenditures, and examined the impact of inpatient characteristics such as sex, age, survived or deceased, length of stay, adult disease, and type of medical care received during the duration of each stay. We analyzed data from the Survey of Medical-Care Activities in Public Health Insurance by multinomial logistic regression analyses. Age of patient had little impact on per capita inpatient health-care expenditures per day. As regards length of stay, inpatient stays of 8-14 days had a little impact on health-care expenditures. This study suggested that these results might be due to the kind of medical care received. More research is needed to determine the appropriate medical services to reduce long-term hospitalization. In the last month of care for patients who died, medical examinations had a great influence on health-care expenditures. This study showed that increasing medical examinations in the end-of-life care needs further investigation.

Vietnamese Immigrant and Refugee Women's Mental Health: An Examination of Age of Arrival, Length of Stay, Income, and English Language Proficiency

ERIC Educational Resources Information Center

Brown, Chris; Schale, Codi L.; Nilsson, Johanna E.

2010-01-01

Vietnamese immigrant and refugee women (N = 83) were surveyed regarding their mental health, English language proficiency, age of arrival, length of stay, and income. English language proficiency and age of arrival correlated with reduced symptomatology. Moreover, English language proficiency was the sole predictor of somatic distress. (Contains 1…

An immediate effect of axial neck rotation training with real time visual feedback using a smartphone inclinometer on improvement in axial neck rotation function.

PubMed

Park, Kyue-Nam; Kwon, Oh-Yun; Kim, Si-Hyun; Jeon, In-Cheol

2017-03-01

The purpose of this study was to compare the immediate effects of axial neck rotation training (Axi-NRT) with and without real-time visual feedback (VF) using a smartphone inclinometer on the range of motion (ROM) for axial neck rotation and the onset of compensatory neck lateral bending and extension during active neck rotation. Twenty participants with restricted ROM for neck rotation but no neck pain (21.1 ± 1.6 years and 8 males, 12 females) were recruited for Axi-NRT with VF, and twenty age- and gender-matched participants with restricted ROM for neck rotation were recruited for Axi-NRT without VF. Changes in ROM for neck rotation and the onset time of compensatory neck movement during active neck rotation were measured using an electromagnetic tracking system. Axi-NRT with VF was more effective in increasing ROM for neck rotation and decreasing and delaying the onset of compensatory neck movements during active neck rotation compared with Axi-NRT without VF. Repeated Axi-NRT using VF is useful to educate participants in maintaining the axis of the cervical spine and to increase ROM for axial neck rotation with less compensatory neck motion in participants with a restricted range of neck rotations.

Insulin acts as a powerful stimulator of axial myopia in chicks.

PubMed

Feldkaemper, Marita P; Neacsu, Irina; Schaeffel, Frank

2009-01-01

In animal models, it has been shown that the retina can use the defocus of the projected image to control emmetropization. Glucagon may be involved in the sign of defocus detection, at least in chickens. Since glucagon and insulin often have opposite effects in metabolic pathways, the effect of insulin on eye growth was investigated. Chicks were treated with either positive or negative spectacle lenses and intravitreally injected with saline or different amounts of insulin. Refraction, axial length, and corneal curvature were measured. Effects of insulin on vitreal glucose concentration, on retinal ZENK and glucagon mRNA levels, and on the number of ZENK-immunoreactive glucagon amacrine cells were studied. Insulin injections (0.3 nmol) caused only a small myopic shift in control chicks. When positive lenses were worn, insulin injections (0.3; 0.03 nmol) not only blocked hyperopia but rather induced high amounts of axial myopia. Insulin also enhanced myopia that was induced by negative lenses. Axial elongation was mostly due to an increase in anterior chamber depth and a thickening of the crystalline lens. Insulin temporarily reduced vitreal glucose levels. Insulin increased retinal ZENK mRNA levels, whereas the number of ZENK-immunoreactive glucagon amacrine cells was reduced, a finding that is typically linked to the development of myopia. Given that insulin is used in therapy for human metabolic disorders and has been proposed to treat corneal epithelial disease, its powerful myopiagenic effect, which is mostly due to its effects on the optics of the anterior segment of the eye, merits further investigation.

MRI Evaluation of Spinal Length and Vertebral Body Angle During Loading with a Spinal Compression Harness

NASA Technical Reports Server (NTRS)

Campbell, James A.; Hargens, Alan R.; Murthy, G.; Ballard, R. E.; Watenpaugh, D. E.; Hargens, Alan, R.; Sanchez, E.; Yang, C.; Mitsui, I.; Schwandt, D.;

Glaucoma in high myopia and parapapillary delta zone

PubMed Central

Weber, Pascal; Nagaoka, Natsuko; Ohno-Matsui, Kyoko

2017-01-01

Purpose To examine the prevalence of glaucomatous optic neuropathy (GON) in a medium myopic to highly myopic group of patients and its association with parapapillary gamma zone and parapapillary delta zone. Methods The retrospective observational hospital-based study included patients who had attended the Tokyo High Myopia Clinics within January 2012 and December 2012 and for whom fundus photographs were available. GON was defined based on the appearance of the optic nerve head on the fundus photographs. Results The study included 519 eyes (262 individuals) with a mean age of 62.0±14.3 years (range:13–89 years) and mean axial length of 29.5±2.2 mm (range:23.2–35.3mm). GON was present in 141 (27.2%; 95% confidence intervals (CI): 23.3, 31.0%) eyes. Prevalence of GON increased from 12.2% (1.7, 22.7) in eyes with an axial length of <26.5mm to 28.5% (24.4, 32.5) in eyes with an axial length of ≥26.5mm, to 32.6% (27.9, 37.2) in eyes with an axial length of ≥28mm, to 36.0% (30.5, 41.4) in eyes with an axial length of ≥29mm, and GON prevalence increased to 42.1% (35.5, 48.8) in eyes with an axial length of ≥30mm. In multivariate analysis, higher GON prevalence was associated (Nagelkerke r2: 0.28) with larger parapapillary delta zone diameter (P<0.001; odds ratio (OR):1.86;95%CI:1.33,2.61), longer axial length (P<0.001;OR:1.45;95%CI:1.26,1.67) and older age (P = 0.01;OR:1.03;95%CI:1.01,1.05). If parapapillary delta zone width was replaced by the vertical disc diameter, higher GON prevalence was associated (r2:0.24) with larger vertical optic disc diameter (P = 0.04;OR:1.70;95%CI:1.03,2.81), after adjusting for longer axial length (P<0.001;OR:1.44;95%CI:1.26,1.64) and older age (P<0.001;OR:1.04;95%CI:1.02,1.06). Conclusions Axial elongation associated increase in GON prevalence (mean: 28.1% in a medium to highly myopic study population) was associated with parapapillary delta zone as surrogate for an elongated peripapillary scleral flange and with larger optic

Behavior of sandwich panels subjected to bending fatigue, axial compression loading and in-plane bending

NASA Astrophysics Data System (ADS)

Mathieson, Haley Aaron

This thesis investigates experimentally and analytically the structural performance of sandwich panels composed of glass fibre reinforced polymer (GFRP) skins and a soft polyurethane foam core, with or without thin GFRP ribs connecting skins. The study includes three main components: (a) out-of-plane bending fatigue, (b) axial compression loading, and (c) in-plane bending of sandwich beams. Fatigue studies included 28 specimens and looked into establishing service life (S-N) curves of sandwich panels without ribs, governed by soft core shear failure and also ribbed panels governed by failure at the rib-skin junction. Additionally, the study compared fatigue life curves of sandwich panels loaded under fully reversed bending conditions (R=-1) with panels cyclically loaded in one direction only (R=0) and established the stiffness degradation characteristics throughout their fatigue life. Mathematical models expressing fatigue life and stiffness degradation curves were calibrated and expanded forms for various loading ratios were developed. Approximate fatigue thresholds of 37% and 23% were determined for non-ribbed panels loaded at R=0 and -1, respectively. Digital imaging techniques showed significant shear contribution significantly (90%) to deflections if no ribs used. Axial loading work included 51 specimens and examined the behavior of panels of various lengths (slenderness ratios), skin thicknesses, and also panels of similar length with various rib configurations. Observed failure modes governing were global buckling, skin wrinkling or skin crushing. In-plane bending involved testing 18 sandwich beams of various shear span-to-depth ratios and skin thicknesses, which failed by skin wrinkling at the compression side. The analytical modeling components of axially loaded panels include; a simple design-oriented analytical failure model and a robust non-linear model capable of predicting the full load-displacement response of axially loaded slender sandwich panels

Effects of age and step length on joint kinetics during stepping task.

PubMed

Bieryla, Kathleen A; Buffinton, Christine

2015-07-16

Following a balance perturbation, a stepping response is commonly used to regain support, and the distance of the recovery step can vary. To date, no other studies have examined joint kinetics in young and old adults during increasing step distances, when participants are required to bring their rear foot forward. Therefore, the purpose of this study was to examine age-related differences in joint kinetics with increasing step distance. Twenty young and 20 old adults completed the study. Participants completed a step starting from double support, at an initial distance equal to the individual's average step length. The distance was increased by 10% body height until an unsuccessful attempt. A one-way, repeated measures ANOVA was used to determine the effects of age on joint kinetics during the maximum step distance. A two-way, repeated measures, mixed model ANOVA was used to determine the effects of age, step distance, and their interaction on joint kinetics during the first three step distances for all participants. Young adults completed a significantly longer step than old adults. During the maximum step, in general, kinetic measures were greater in the young than in the old. As step distance increased, all but one kinetic measure increased for both young and old adults. This study has shown the ability to discriminate between young and old adults, and could potentially be used in the future to distinguish between fallers and non-fallers. Copyright © 2015 Elsevier Ltd. All rights reserved.

Altering the axial light gradient affects photomorphogenesis in emerging seedlings of Zea mays L

NASA Technical Reports Server (NTRS)

Parks, B. M.; Poff, K. L.

1986-01-01

The axial (longitudinal) red light gradient (632 nanometers) of 4 day old dark-grown maize seedlings is increased by staining the peripheral cells of the coleoptile. The magnitude of increase in the light gradient is dependent solely on the light-absorbing qualities of the stain used. Metanil yellow has no effect on the axial red-light gradient, while methylene blue causes a large increase in this light gradient. These stains did not affect growth in darkness or the sensitivity of mesocotyl elongation to red light. However, mesocotyl elongation was altered for the dark-grown seedlings stained with methylene blue when these seedlings were transplanted, covered with soil, and permitted to emerge under natural lighting conditions. These observations are consistent with the idea that there is a single perceptive site below the coleoptilar node, and suggest that this perceptive site gives the actinic light which has traveled downward through the length of the shoot from an entry point in the plant tip region.

Glycoconjugate distribution in early human notochord and axial mesenchyme.

PubMed

Götz, W; Quondamatteo, F

2001-02-01

Glycosylation patterns of cells and tissues give insights into spatially and temporally regulated developmental processes and can be detected histochemically using plant lectins with specific affinities for sugar moieties. The early development of the vertebral column in man is a process which has never been investigated by lectin histochemistry. Therefore, we studied binding of several lectins (AIA, Con A, GSA II, LFA, LTA, PNA, RCA I, SBA, SNA, WGA) in formaldehyde-fixed sections of the axial mesenchyme of 5 human embryos in Carnegie stages 12-15. During these developmental stages, an unsegmented mesenchyme covers the notochord. Staining patterns did not show striking temporal variations except for SBA which stained the cranial axial mesenchyme only in the early stage 12 embryo and for PNA, of which the staining intensity in the mesenchyme decreased with age. The notochord appeared as a highly glycosylated tissue. Carbohydrates detected may correspond to adhesion molecules or to secreted substances like proteoglycans or proteins which could play an inductive role, for example, for the neural tube. The axial perinotochordal unsegmented mesenchyme showed strong PNA binding. Therefore, its function as a PNA-positive "barrier" tissue is discussed. The endoderm of the primitive gut showed a lectin-binding pattern that was similar to that of the notochord, which may correlate with interactions between these tissues during earlier developmental stages.

A Study of Laminar Compressible Viscous Pipe Flow Accelerated by an Axial Body Force, with Application to Magnetogasdynamics

NASA Technical Reports Server (NTRS)

Martin, E. Dale

1961-01-01

A study is made of the steady laminar flow of a compressible viscous fluid in a circular pipe when the fluid is accelerated by an axial body force. The application of the theory to the magnetofluidmechanics of an electrically conducting gas accelerated by electric and magnetic fields is discussed. Constant viscosity, thermal conductivity, and electrical conductivity are assumed. Fully developed flow velocity and temperature profiles are shown, and detailed results of the accelerating flow development, including velocity and pressure as functions of distance, are given for the case where the axial body force is constant and for the case where it is a linear function of velocity. From these results are determined the pipe entry length and the pressure difference required.

Axial flow heat exchanger devices and methods for heat transfer using axial flow devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

Koplow, Jeffrey P.

Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferredmore » across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.« less

Inverse axial mounting stiffness design for lithographic projection lenses.

PubMed

Wen-quan, Yuan; Hong-bo, Shang; Wei, Zhang

2014-09-01

In order to balance axial mounting stiffness of lithographic projection lenses and the image quality under dynamic working conditions, an easy inverse axial mounting stiffness design method is developed in this article. Imaging quality deterioration at the wafer under different axial vibration levels is analyzed. The desired image quality can be determined according to practical requirements, and axial vibrational tolerance of each lens is solved with the damped least-squares method. Based on adaptive interval adjustment, a binary search algorithm, and the finite element method, the axial mounting stiffness of each lens can be traveled in a large interval, and converges to a moderate numerical solution which makes the axial vibrational amplitude of the lens converge to its axial vibrational tolerance. Model simulation is carried out to validate the effectiveness of the method.

Increased telomere length and proliferative potential in peripheral blood mononuclear cells of adults of different ages stimulated with concanavalin A

PubMed Central

2013-01-01

Background Recently, a direct correlation with telomere length, proliferative potential and telomerase activity has been found in the process of aging in peripheral blood cells. The objective of the study was to evaluate telomere length and proliferative potential in peripheral blood mononuclear cells (PBMCs) after stimulation with Concanavalin A (ConA) of young adults compared with older adults. Methods Blood samples were obtained from 20 healthy young males (20–25 years old) (group Y) and 20 males (60–65 years old) (group O). We compared PBMC proliferation before and after stimulation with ConA. DNA was isolated from cells separated before and after culture with ConA for telomeric measurement by real-time polymerase chain reaction. Results In vitro stimulation of PBMCs from young subjects induced an increase of telomere length as well as a higher replicative capacity of cell proliferation. Samples from older adults showed higher loss of telomeric DNA (p = 0.03) and higher levels of senescent (≤6.2 kb) telomeric DNA (p = 0.02) and displayed a marked decrease of proliferation capacity. Viability cell counts and CFSE tracking in 72-h-old cell cultures indicated that group O PBMCs (CD8+ and CD4+ T cells) underwent fewer mitotic cycles and had shorter telomeres than group Y (p = 0.04). Conclusions Our findings confirm that telomere length in older-age adults is shorter than in younger subjects. After stimulation with ConA, cells are not restored to the previous telomere length and undergo replicative senescence. This is in sharp contrast to the response observed in young adults after ConA stimulation where cells increase in telomere length and replicative capacity. The mechanisms involved in this phenomenon are not yet clear and merit further investigation. PMID:24063536

Application of the line-spring model to a cylindrical shell containing a circumferential or axial part-through crack

NASA Technical Reports Server (NTRS)

Delale, F.; Erdogan, F.

1981-01-01

An approximate solution was obtained for a cylindrical shell containing a part-through surface crack. It was assumed that the shell contains a circumferential or axial semi-elliptic internal or external surface crack and was subjected to a uniform membrane loading or a uniform bending moment away from the crack region. A Reissner type theory was used to account for the effects of the transverse shear deformations. The stress intensity factor at the deepest penetration point of the crack was tabulated for bending and membrane loading by varying three dimensionless length parameters of the problem formed from the shell radius, the shell thickness, the crack length, and the crack depth. The upper bounds of the stress intensity factors are provided by the results of the elasticity solution obtained from the axisymmetric crack problem for the circumferential crack, and that found from the plane strain problem for a circular ring having a radial crack for the axial crack. The line-spring model gives the expected results in comparison with the elasticity solutions. Results also compare well with the existing finite element solution of the pressurized cylinder containing an internal semi-elliptic surface crack.

Axial Compressor Reversed Flow Performance.

DTIC Science & Technology

1985-05-01

5.3.2. Axial Tempature Profils TIme-verage axial temperature profiles were acquired through the use of exposed...on the above questions, or any additional details concerning the current application, future potential, or other value of this research. Please use the...were heavily dependent upon the model used for defining compressor post-stall performance, both steady state end transient, especially In the reve a

Liquid rocket engine axial-flow turbopumps

NASA Technical Reports Server (NTRS)

Scheer, D. D.; Huppert, M. C.; Viteri, F.; Farquhar, J.; Keller, R. B., Jr. (Editor)

1978-01-01

The axial pump is considered in terms of the total turbopump assembly. Stage hydrodynamic design, pump rotor assembly, pump materials for liquid hydrogen applications, and safety factors as utilized in state of the art pumps are among the topics discussed. Axial pump applications are included.

Age-related changes in molar topography and shearing crest length in a wild population of mountain Gorillas from Volcanoes National Park, Rwanda.

PubMed

Glowacka, Halszka; McFarlin, Shannon C; Catlett, Kierstin K; Mudakikwa, Antoine; Bromage, Timothy G; Cranfield, Michael R; Stoinski, Tara S; Schwartz, Gary T

2016-05-01

Great ape teeth must remain functional over long lifespans. The molars of the most folivorous apes, the mountain gorillas, must maintain shearing function for 40+ years while the animals consume large quantities of mechanically challenging foods. While other folivorous primates experience dental senescence, which compromises their occlusal surfaces and affects their reproductive success as they age, it is unknown whether dental senescence also occurs in mountain gorillas. In this article, we quantified and evaluated how mountain gorilla molars change throughout their long lifespans. We collected high-resolution replicas of M(1)s (n = 15), M(2)s (n = 13), and M(3)s (n = 11) from a cross-sectional sample of wild mountain gorilla skeletons from the Virunga Volcanoes, ranging in age from 4 to 43 years. We employed dental topographic analyses to track how aspects of occlusal slope, angularity, relief index, and orientation patch count rotated change with age. In addition, we measured the relative length of shearing crests in two- and three-dimensions. Occlusal topography was found to decrease, while 2D relative shearing crest length increased, and 3D relative crest lengths were maintained with age. Our findings indicate that shearing function is maintained throughout the long lifetimes of mountain gorillas. Unlike the dental senescence experienced by other folivorous primates, mountain gorillas do not appear to possess senesced molars despite their long lifetimes, mechanically challenging diets, and decreases in occlusal topography with age. © 2016 Wiley Periodicals, Inc.

Cyclic Axial-Torsional Deformation Behavior of a Cobalt-Base Superalloy

NASA Technical Reports Server (NTRS)

Bonacuse, Peter J.; Kalluri, Sreeramesh

1995-01-01

The cyclic, high-temperature deformation behavior of a wrought cobalt-base super-alloy, Haynes 188, is investigated under combined axial and torsional loads. This is accomplished through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue database has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gage section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. The fatigue behavior of Haynes 188 at 760 C under axial, torsional, and combined axial-torsional loads and the monotonic and cyclic deformation behaviors under axial and torsional loads have been previously reported. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress ,versus engineering shear strain, axial strain versus engineering shear strain. and axial stress versus shear stress spaces are presented for cyclic in-phase and out-of-phase axial-torsional tests. For in-phase tests, three different values of the proportionality constant lambda (the ratio of engineering shear strain amplitude to axial strain amplitude, are examined, viz. 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 degrees with lambda equals 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress-strain and the maximum shear stress-maximum engineering shear strain (Tresca) curves. Comparisons are also made between the hardening behaviors of cyclic axial, torsional, and combined in-phase (lambda = 1.73 and phi = 0) and out-of-phase (lambda = 1.73 and phi = 90') axial-torsional fatigue tests. These comparisons

Soda and cell aging: associations between sugar-sweetened beverage consumption and leukocyte telomere length in healthy adults from the National Health and Nutrition Examination Surveys.

PubMed

Leung, Cindy W; Laraia, Barbara A; Needham, Belinda L; Rehkopf, David H; Adler, Nancy E; Lin, Jue; Blackburn, Elizabeth H; Epel, Elissa S

2014-12-01

We tested whether leukocyte telomere length maintenance, which underlies healthy cellular aging, provides a link between sugar-sweetened beverage (SSB) consumption and the risk of cardiometabolic disease. We examined cross-sectional associations between the consumption of SSBs, diet soda, and fruit juice and telomere length in a nationally representative sample of healthy adults. The study population included 5309 US adults, aged 20 to 65 years, with no history of diabetes or cardiovascular disease, from the 1999 to 2002 National Health and Nutrition Examination Surveys. Leukocyte telomere length was assayed from DNA specimens. Diet was assessed using 24-hour dietary recalls. Associations were examined using multivariate linear regression for the outcome of log-transformed telomere length. After adjustment for sociodemographic and health-related characteristics, sugar-sweetened soda consumption was associated with shorter telomeres (b = -0.010; 95% confidence interval [CI] = -0.020, -0.001; P = .04). Consumption of 100% fruit juice was marginally associated with longer telomeres (b = 0.016; 95% CI = -0.000, 0.033; P = .05). No significant associations were observed between consumption of diet sodas or noncarbonated SSBs and telomere length. Regular consumption of sugar-sweetened sodas might influence metabolic disease development through accelerated cell aging.

Soda and Cell Aging: Associations Between Sugar-Sweetened Beverage Consumption and Leukocyte Telomere Length in Healthy Adults From the National Health and Nutrition Examination Surveys

PubMed Central

Laraia, Barbara A.; Needham, Belinda L.; Rehkopf, David H.; Adler, Nancy E.; Lin, Jue; Blackburn, Elizabeth H.

2014-01-01

Objectives. We tested whether leukocyte telomere length maintenance, which underlies healthy cellular aging, provides a link between sugar-sweetened beverage (SSB) consumption and the risk of cardiometabolic disease. Methods. We examined cross-sectional associations between the consumption of SSBs, diet soda, and fruit juice and telomere length in a nationally representative sample of healthy adults. The study population included 5309 US adults, aged 20 to 65 years, with no history of diabetes or cardiovascular disease, from the 1999 to 2002 National Health and Nutrition Examination Surveys. Leukocyte telomere length was assayed from DNA specimens. Diet was assessed using 24-hour dietary recalls. Associations were examined using multivariate linear regression for the outcome of log-transformed telomere length. Results. After adjustment for sociodemographic and health-related characteristics, sugar-sweetened soda consumption was associated with shorter telomeres (b = –0.010; 95% confidence interval [CI] = −0.020, −0.001; P = .04). Consumption of 100% fruit juice was marginally associated with longer telomeres (b = 0.016; 95% CI = −0.000, 0.033; P = .05). No significant associations were observed between consumption of diet sodas or noncarbonated SSBs and telomere length. Conclusions. Regular consumption of sugar-sweetened sodas might influence metabolic disease development through accelerated cell aging. PMID:25322305

Leukocyte telomere length dynamics in women and men: menopause vs age effects

PubMed Central

Dalgård, Christine; Benetos, Athanase; Verhulst, Simon; Labat, Carlos; Kark, Jeremy D; Christensen, Kaare; Kimura, Masayuki; Kyvik, Kirsten Ohm; Aviv, Abraham

2015-01-01

Background: A longer leukocyte telomere length (LTL) in women than men has been attributed to a slow rate of LTL attrition in women, perhaps due to high estrogen exposure during the premenopausal period. Methods: To test this premise we performed a longitudinal study (an average follow-up of 12 years) in a subset of the population-based Danish National Twin Registry. Participants consisted of 405 women, aged 37.5 (range 18.0–64.3) years, and 329 men, aged 38.8 (range 18.0–58.5) years, at baseline examination. Results: Women showed a longer LTL [kb ± standard error(SE)] than men (baseline: 7.01 ± 0.03 vs 6.87 ± 0.04; follow-up: 6.79 ± 0.03 vs 6.65 ± 0.03; both P = 0.005). Women displayed deceleration of LTL attrition (bp/years ± SE), as they transitioned from the premenopausal period (20.6 ± 1.0) through the perimenopausal period (16.5 ± 1.3) to the postmenopausal period (15.1 ± 1.7). Age was not associated with LTL attrition in women after statistical control for menopausal status. Men, in contrast, displayed a trend for age-dependent increase in the rate of LTL attrition, which differed significantly from the pattern in women (P for interaction = 0.01). Conclusions: Results indicate that the premenopausal period is expressed in a higher rate of LTL attrition than the postmenopausal period. They further suggest that the sex gap in LTL stems from earlier ages—the period of growth and development. The higher rate of LTL attrition in premenopausal women, we propose, might relate to estrogen-mediated increased turnover of erythrocytes, menstrual bleeding or both. PMID:26385867

Gestational length assignment based on last menstrual period, first trimester crown-rump length, ovulation, and implantation timing.

PubMed

Mahendru, Amita A; Wilhelm-Benartzi, Charlotte S; Wilkinson, Ian B; McEniery, Carmel M; Johnson, Sarah; Lees, Christoph

2016-10-01

Understanding the natural length of human pregnancy is central to clinical care. However, variability in the reference methods to assign gestational age (GA) confound our understanding of pregnancy length. Assignation from ultrasound measurement of fetal crown-rump length (CRL) has superseded that based on last menstrual period (LMP). Our aim was to estimate gestational length based on LMP, ultrasound CRL, and implantation that were known, compared to pregnancy duration assigned by day of ovulation. Prospective study in 143 women trying to conceive. In 71 ongoing pregnancies, gestational length was estimated from LMP, CRL at 10-14 weeks, ovulation, and implantation day. For each method of GA assignment, the distribution in observed gestational length was derived and both agreement and correlation between the methods determined. Median ovulation and implantation days were 16 and 27, respectively. The gestational length based on LMP, CRL, implantation, and ovulation was similar: 279, 278, 276.5 and 276.5 days, respectively. The distributions for observed gestational length were widest where GA was assigned from CRL and LMP and narrowest when assigned from implantation and ovulation day. The strongest correlation for gestational length assessment was between ovulation and implantation (r = 0.98) and weakest between CRL and LMP (r = 0.88). The most accurate method of predicting gestational length is ovulation day, and this agrees closely with implantation day. Prediction of gestational length from CRL and known LMP are both inferior to ovulation and implantation day. This information could have important implications on the routine assignment of gestational age.

Radial/axial power divider/combiner

NASA Technical Reports Server (NTRS)

Vaddiparty, Yerriah P. (Inventor)

1987-01-01

An electromagnetic power divider/combiner comprises N radial outputs (31) having equal powers and preferably equal phases, and a single axial output (20). A divider structure (1) and a preferably identical combiner structure (2) are broadside coupled across a dielectric substrate (30) containing on one side the network of N radial outputs (31) and on its other side a set of N equispaced stubs (42) which are capacitively coupled through the dielectric substrate (30) to the N radial outputs (31). The divider structure (1) and the combiner structure (2) each comprise a dielectric disk (12, 22, respectively) on which is mounted a set of N radial impedance transformers (14, 24, respectively). Gross axial coupling is determined by the thickness of the dielectric layer (30). Rotating the disks (12, 22) with respect to each other effectuates fine adjustment in the degree of axial coupling.

[Eye development in children. Part I. Eyeball dimensions].

PubMed

Lachowicz, Ewelina; Czepita, Damian

2010-01-01

The aim of an article is to introduce and elaborate on the available literature concerning eyeball development. The information content in the article comes from studies performed on groups of children of different ages. In some analysis study groups were chosen depending on sex. Axial length of the eye, depth of anterior chamber, lens's thickness and vitreous's dimension was defined. Intensive changes of eyeball dimensions progress with age. A period of fast and slow growth of the eye can be discerned. Axial length of the eye, depth of anterior chamber, lens's thickness and vitreous's dimension increase over time. Growth of the axial length is mainly caused by increasing axial length of vitreous cavity. The increase in depth of the anterior chamber plays a lesser role. Girls tend to have shorter eyes compared with boys. Both age and male gender are associated with deeper anterior chambers and larger vitreous cavity. Lens thickness decreases with the growth of the eyeball. However gender does not play a role. Based on current literature, it is difficult exactly indicate what are the standards of eyeball growth in children and youths. To establish these parameters, further studies on the another examination in representative group of children and teenagers are necessary.

Comparison of femoropopliteal artery stents under axial and radial compression, axial tension, bending, and torsion deformations.

PubMed

Maleckis, Kaspars; Deegan, Paul; Poulson, William; Sievers, Cole; Desyatova, Anastasia; MacTaggart, Jason; Kamenskiy, Alexey

2017-11-01

High failure rates of Peripheral Arterial Disease (PAD) stenting appear to be associated with the inability of certain stent designs to accommodate severe biomechanical environment of the femoropopliteal artery (FPA) that bends, twists, and axially compresses during limb flexion. Twelve Nitinol stents (Absolute Pro, Supera, Lifestent, Innova, Zilver, Smart Control, Smart Flex, EverFlex, Viabahn, Tigris, Misago, and Complete SE) were quasi-statically tested under bench-top axial and radial compression, axial tension, bending, and torsional deformations. Stents were compared in terms of force-strain behavior, stiffness, and geometrical shape under each deformation mode. Tigris was the least stiff stent under axial compression (6.6N/m axial stiffness) and bending (0.1N/m) deformations, while Smart Control was the stiffest (575.3N/m and 105.4N/m, respectively). Under radial compression Complete SE was the stiffest (892.8N/m), while Smart Control had the lowest radial stiffness (211.0N/m). Viabahn and Supera had the lowest and highest torsional stiffness (2.2μNm/° and 959.2μNm/°), respectively. None of the 12 PAD stents demonstrated superior characteristics under all deformation modes and many experienced global buckling and diameter pinching. Though it is yet to be determined which of these deformation modes might have greater clinical impact, results of the current analysis may help guide development of new stents with improved mechanical characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.

Factors Influencing Central Lamina Cribrosa Depth: A Multicenter Study

PubMed Central

Luo, Haomin; Yang, Hongli; Gardiner, Stuart K.; Hardin, Christy; Sharpe, Glen P.; Caprioli, Joseph; Demirel, Shaban; Girkin, Christopher A.; Liebmann, Jeffrey M.; Mardin, Christian Y.; Quigley, Harry A.; Scheuerle, Alexander F.; Fortune, Brad; Chauhan, Balwantray C.; Burgoyne, Claude F.

2018-01-01

Purpose To quantify the influence of ocular and demographic factors on central laminar depth (LD) in healthy participants. Methods A total of 362 normal subjects underwent optical coherence tomography (OCT) enhanced depth imaging of the optic nerve head (ONH) with a 24 radial B-scan pattern aligned to the fovea–to–Bruch's membrane opening (BMO) axis. BMO, anterior lamina, anterior scleral canal opening (ASCO), Bruch's membrane (BM), and the peripapillary scleral surface were manually segmented. The extent of laminar segmentation was quantified within 72 ASCO subsectors. Central LD was quantified relative to four reference planes: BMO, ASCO, BM, and scleral. The effects of age, sex, ethnicity, IOP, BMO area, ASCO area, and axial length on LD were assessed. Results Laminar visibility was most consistent within the central ASCO (median 89%, range, 69%–95%). LDBMO and LDBM were significantly shallower in eyes with greater age, BMO area, and axial length and in females. LDASCO was shallower in eyes with greater ASCO area and axial length and in European and Hispanic descent compared to African descent eyes. LDSclera behaved similarly, but was not associated with axial length. BMO and ASCO area were not different between African descent and European descent eyes. Conclusions Central LD was deeper in African descent eyes and influenced least by age, axial length, and sex, but more by ASCO area, when measured relative to the ASCO and sclera. However, the magnitude of these effects for all four reference planes was small, and their clinical importance in the detection of glaucoma and its progression remains to be determined. PMID:29847642

Sonographic Measurement of Fetal Ear Length in Turkish Women with a Normal Pregnancy

PubMed Central

Özdemir, Mucize Eriç; Uzun, Işıl; Karahasanoğlu, Ayşe; Aygün, Mehmet; Akın, Hale; Yazıcıoğlu, Fehmi

2014-01-01

Background: Abnormal fetal ear length is a feature of chromosomal disorders. Fetal ear length measurement is a simple measurement that can be obtained during ultrasonographic examinations. Aims: To develop a nomogram for fetal ear length measurements in our population and investigate the correlation between fetal ear length, gestational age, and other standard fetal biometric measurements. Study Design: Cohort study. Methods: Ear lengths of the fetuses were measured in normal singleton pregnancies. The relationship between gestational age and fetal ear length in millimetres was analysed by simple linear regression. In addition, the correlation of fetal ear length measurements with biparietal diameter, head circumference, abdominal circumference, and femur length were evaluated.Ear length measurements were obtained from fetuses in 389 normal singleton pregnancies ranging between 16 and 28 weeks of gestation. Results: A nomogram was developed by linear regression analysis of the parameters ear length and gestational age. Fetal ear length (mm) = y = (1.348 X gestational age)−12.265), where gestational ages is in weeks. A high correlation was found between fetal ear length and gestational age, and a significant correlation was also found between fetal ear length and the biparietal diameter (r=0.962; p<0.001). Similar correlations were found between fetal ear length and head circumference, and fetal ear length and femur length. Conclusion: The results of this study provide a nomogram for fetal ear length. The study also demonstrates the relationship between ear length and other biometric measurements. PMID:25667783

Animated axial surface mapping: The multimedia companion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hook, S.C.; Shaw, J.H.; Suppe, J.

1995-09-01

This newly expanded version of AAPG`s first DataShare Disk brings to life the concepts and applications of a new method of structural trend analysis. Through the dynamic use of color, sound, animation, and humor, this multimedia companion to the May 1994 article on Axial Surface Mapping introduces the reader (or viewer) to the concepts of rigid-block translation, fault-bend folding, and axial surface mapping. Animated models of growing fault-bend folds allow the viewer to see in four dimensions. The axial surface map shows the horizontal plane; the folding lines show depth planes; and the animations show the structure and its two-dimensionalmore » map changing with time and increasing slip. The animations create theoretical map patterns under varying, but controlled conditions that can be compared to axial surface maps from real data. The model patterns are then used to interpret seismic data and axial surface maps from a producing gas field in offshore California and from an exploration play in Pennsylvania.« less

Comparison of ophthalmic measurements obtained via high-frequency ultrasound imaging in four species of snakes.

PubMed

Hollingsworth, Steven R; Holmberg, Bradford J; Strunk, Anneliese; Oakley, Alicia D; Sickafoose, Leann M; Kass, Philip H

2007-10-01

To measure the dimensions of the eyes of living snakes by use of high-frequency ultrasound imaging and correlate those measurements with age, length, and weight. Animals-14 clinically normal snakes. Species, age, length, weight, and horizontal spectacle diameter were recorded, and each snake underwent physical and ophthalmic examinations; ultrasonographic examination of both eyes was performed by use of a commercially available ultrasound unit and a 50-MHz transducer. Ultrasonographic measurements included spectacle thickness, subspectacular space depth, corneal thickness, anterior chamber depth, lens thickness, vitreous cavity depth, and globe length. All measurements were made along the visual axis. 2 corn snakes, 5 California king snakes, 1 gopher snake, and 6 ball pythons were examined. There were no significant differences within or between the species with regard to mean spectacle thickness, corneal thickness, or subspectacular space depth. However, mean horizontal spectacle diameter, anterior chamber depth, and axial globe length differed among the 4 species; for each measurement, ball pythons had significantly larger values than California king snakes. Spectacle thickness, subspectacular space depth, and corneal thickness were similar among the species of snake examined and did not vary significantly with age, length, or weight. Measurements of these dimensions can potentially serve as baseline values to evaluate snakes of these species with a retained spectacle, subspectacular abscess, or subspectacular fluid accumulation. Anterior chamber depth and axial length appeared variable among species, but axial length did not vary with age, length, or weight in the species studied.

Wave propagation in axially moving periodic strings

NASA Astrophysics Data System (ADS)

Sorokin, Vladislav S.; Thomsen, Jon Juel

2017-04-01

The paper deals with analytically studying transverse waves propagation in an axially moving string with periodically modulated cross section. The structure effectively models various relevant technological systems, e.g. belts, thread lines, band saws, etc., and, in particular, roller chain drives for diesel engines by capturing both their spatial periodicity and axial motion. The Method of Varying Amplitudes is employed in the analysis. It is shown that the compound wave traveling in the axially moving periodic string comprises many components with different frequencies and wavenumbers. This is in contrast to non-moving periodic structures, for which all components of the corresponding compound wave feature the same frequency. Due to this "multi-frequency" character of the wave motion, the conventional notion of frequency band-gaps appears to be not applicable for the moving periodic strings. Thus, for such structures, by frequency band-gaps it is proposed to understand frequency ranges in which the primary component of the compound wave attenuates. Such frequency band-gaps can be present for a moving periodic string, but only if its axial velocity is lower than the transverse wave speed, and, the higher the axial velocity, the narrower the frequency band-gaps. The revealed effects could be of potential importance for applications, e.g. they indicate that due to spatial inhomogeneity, oscillations of axially moving periodic chains always involve a multitude of frequencies.

Feasibility Study of an Axially Extendable Multiplex Cylinder PET

NASA Astrophysics Data System (ADS)

Yoshida, Eiji; Hirano, Yoshiyuki; Tashima, Hideaki; Inadama, Naoko; Nishikido, Fumihiko; Murayama, Hideo; Ito, Hiroshi; Yamaya, Taiga

2013-10-01

Current clinical PET scanners have a 15-22 cm axial field-of-view (FOV). These scanners image the whole body using six or more bed positions. We designed an axially extendable multiplex cylinder (AEMC) PET scanner to provide high versatility for clinical and research studies using semiconductor photo-sensor based, depth-of-interaction (DOI) detectors. Since silicon-photomultipliers (Si-PMs) have high gain like conventional photomultiplier tubes and a compact design, the Si-PM-based detector is particularly expected to enable various new detector arrangements. The AEMC-PET scanner consists of multiple independent and laminated detector rings using the DOI detectors. The AEMC-PET scanner can extend the axial FOV as each stacked detector ring can be slid sideways. When this PET scanner is used for the four-layer DOI detector, its minimum axial FOV is 24 cm and its maximum crystal thickness is 3 cm. On the other hand, the axial FOV can be extended to 96 cm when laminated detector rings are slid sideways, but the crystal thickness must be 1/4 of 3 cm. In this work, we evaluated performance characteristics of the PET scanner with a variable axial FOV using Monte Carlo simulation. From the simulation of the 180-cm line source, the 96-cm axial FOV was found to have two-fold better sensitivity compared to the 24-cm axial FOV. For extension of the axial FOV, scatter and attenuation of oblique lines-of-response reduced the yield of true coincidences, but effects of scatter and attenuation were small. Conclusive results were obtained showing the 52.8-cm axial FOV yielded an increase in the noise equivalent count rate of approximately 30% relative to the 24-cm axial FOV. We expect the designed AEMC-PET scanner will provide high versatility in applications such as for measuring whole-body tracer uptakes while keeping the continuous axial FOV; as well, the scan time for static images will be reduced for a comparable number of detectors as conventional PET scanners.

Axially adjustable magnetic properties in arrays of multilayered Ni/Cu nanowires with variable segment sizes

NASA Astrophysics Data System (ADS)

Shirazi Tehrani, A.; Almasi Kashi, M.; Ramazani, A.; Montazer, A. H.

2016-07-01

Arrays of multilayered Ni/Cu nanowires (NWs) with variable segment sizes were fabricated into anodic aluminum oxide templates using a pulsed electrodeposition method in a single bath for designated potential pulse times. Increasing the pulse time between 0.125 and 2 s in the electrodeposition of Ni enabled the formation of segments with thicknesses ranging from 25 to 280 nm and 10-110 nm in 42 and 65 nm diameter NWs, respectively, leading to disk-shaped, rod-shaped and/or near wire-shaped geometries. Using hysteresis loop measurements at room temperature, the axial and perpendicular magnetic properties were investigated. Regardless of the segment geometry, the axial coercivity and squareness significantly increased with increasing Ni segment thickness, in agreement with a decrease in calculated demagnetizing factors along the NW length. On the contrary, the perpendicular magnetic properties were found to be independent of the pulse times, indicating a competition between the intrawire interactions and the shape demagnetizing field.

Investigation of Fluctuation-Induced Electron Transport in Hall Thrusters with a 2D Hybrid Code in the Azimuthal and Axial Coordinates

NASA Astrophysics Data System (ADS)

Fernandez, Eduardo; Borelli, Noah; Cappelli, Mark; Gascon, Nicolas

2003-10-01

Most current Hall thruster simulation efforts employ either 1D (axial), or 2D (axial and radial) codes. These descriptions crucially depend on the use of an ad-hoc perpendicular electron mobility. Several models for the mobility are typically invoked: classical, Bohm, empirically based, wall-induced, as well as combinations of the above. Experimentally, it is observed that fluctuations and electron transport depend on axial distance and operating parameters. Theoretically, linear stability analyses have predicted a number of unstable modes; yet the nonlinear character of the fluctuations and/or their contribution to electron transport remains poorly understood. Motivated by these observations, a 2D code in the azimuthal and axial coordinates has been written. In particular, the simulation self-consistently calculates the azimuthal disturbances resulting in fluctuating drifts, which in turn (if properly correlated with plasma density disturbances) result in fluctuation-driven electron transport. The characterization of the turbulence at various operating parameters and across the channel length is also the object of this study. A description of the hybrid code used in the simulation as well as the initial results will be presented.

Relationship between interpersonal sensitivity and leukocyte telomere length.

PubMed

Suzuki, Akihito; Matsumoto, Yoshihiko; Enokido, Masanori; Shirata, Toshinori; Goto, Kaoru; Otani, Koichi

2017-10-10

Telomeres are repetitive DNA sequences located at the ends of chromosomes, and telomere length represents a biological marker for cellular aging. Interpersonal sensitivity, excessive sensitivity to the behavior and feelings of others, is one of the vulnerable factors to depression. In the present study, we examined the effect of interpersonal sensitivity on telomere length in healthy subjects. The subjects were 159 unrelated healthy Japanese volunteers. Mean age ± SD (range) of the subjects was 42.3 ± 7.8 (30-61) years. Interpersonal sensitivity was assessed by the Japanese version of the Interpersonal Sensitivity Measure (IPSM). Leukocyte telomere length was determined by a quantitative real-time PCR method. Higher scores of the total IPSM were significantly (β = -0.163, p = 0.038) related to shorter telomere length. In the sub-scale analysis, higher scores of timidity were significantly (β = -0.220, p = 0.044) associated with shorter telomere length. The present study suggests that subjects with higher interpersonal sensitivity have shorter leukocyte telomere length, implying that interpersonal sensitivity has an impact on cellular aging.

Biomechanical optimization of implant diameter and length for immediate loading: a nonlinear finite element analysis.

PubMed

Kong, Liang; Gu, Zexu; Li, Tao; Wu, Junjie; Hu, Kaijin; Liu, Yanpu; Zhou, Hongzhi; Liu, Baolin

2009-01-01

A nonlinear finite element method was applied to examine the effects of implant diameter and length on the maximum von Mises stresses in the jaw, and to evaluate the maximum displacement of the implant-abutment complex in immediate-loading models. The implant diameter (D) ranged from 3.0 to 5.0 mm and implant length (L) ranged from 6.0 to 16.0 mm. The results showed that the maximum von Mises stress in cortical bone was decreased by 65.8% under a buccolingual load with an increase in D. In cancellous bone, it was decreased by 71.5% under an axial load with an increase in L. The maximum displacement in the implant-abutment complex decreased by 64.8% under a buccolingual load with an increase in D. The implant was found to be more sensitive to L than to D under axial loads, while D played a more important role in enhancing its stability under buccolingual loads. When D exceeded 4.0 mm and L exceeded 11.0 mm, both minimum stress and displacement were obtained. Therefore, these dimensions were the optimal biomechanical selections for immediate-loading implants in type B/2 bone.

Characteristics of Modic changes in cervical kyphosis and their association with axial neck pain.

PubMed

An, Yonghui; Li, Jia; Li, Yongqian; Shen, Yong

2017-01-01

The purpose of this study was to evaluate characteristics of Modic changes in cervical kyphosis (CK) and their association with axial neck pain. Study participants included 286 asymptomatic or symptomatic patients with CK (mean age = 54.2 ± 12.2 years) who were consecutively enrolled from March 2009 to October 2015. Clinical and radiographic evaluations were performed at a university outpatient department. CK was classified as global type, reverse sigmoid type, or sigmoid type. There were 138 participants with global type CK, 103 with reverse sigmoid type CK, and 45 with sigmoid type CK. Of the 286 participants, 102 had Modic changes (Modic-1 in 38 segments and Modic-2 in 75 segments). Spinal cord compression grade and disc degeneration occurred more frequently in the group with axial neck pain compared to the group without pain. Angular motion was decreased in those with axial neck pain (mean ± standard deviation [SD] 7.8°±4.6°) compared to those who were asymptomatic (mean ± SD 8.9°±5.1°; P <0.001). In multivariate logistic regression analysis, Modic changes were associated with axial neck pain (odds ratio =5.356; 95% confidence interval =1.314-12.800; P <0.001). Modic changes occur most commonly in association with CK global type and less commonly with reverse sigmoid type and sigmoid type. Modic changes are associated with axial neck pain in patients with CK.

Δ(1232) axial charge and form factors from lattice QCD.

PubMed

Alexandrou, Constantia; Gregory, Eric B; Korzec, Tomasz; Koutsou, Giannis; Negele, John W; Sato, Toru; Tsapalis, Antonios

2011-09-30

We present the first calculation on the Δ axial vector and pseudoscalar form factors using lattice QCD. Two Goldberger-Treiman relations are derived and examined. A combined chiral fit is performed to the nucleon axial charge, N to Δ axial transition coupling constant and Δ axial charge.

Aging and visual length discrimination: sequential dependencies, biases, and the effects of multiple implicit standards.

PubMed

Norman, J Farley; Cheeseman, Jacob R; Baxter, Michael W; Thomason, Kelsey E; Adkins, Olivia C; Rogers, Connor E

2014-05-01

Younger (20-25 years of age) and older (61-79 years) adults were evaluated for their ability to visually discriminate length. Almost all experiments that have utilized the method of single stimuli to date have required participants to judge test stimuli relative to a single implicit standard (for a rare exception, see Morgan, On the scaling of size judgements by orientational cues, Vision Research, 1992, 32, 1433-1445). In the current experiments, we not only asked participants to judge lengths relative to a single implicit standard, but they also compared test stimuli to two different implicit standards within the same blocks of trials. We analyzed our participants' judgments to evaluate whether significant sequential dependencies occurred. We found that while individual younger and older adults possessed similar length difference thresholds and exhibited similar overall biases, the judgments of older adults within individual blocks of trials were more strongly biased (than younger adults) by preceding responses (i.e., their judgments on any given trial were more strongly affected by responses to previously viewed stimuli). In addition, the judgments of both younger and older adults were more strongly biased by preceding responses in the blocks of trials with multiple implicit standards. Overall, our results are consistent with the operation of the tracking mechanism described by Criterion-setting theory (Lages and Treisman, Spatial frequency discrimination: Visual long-term memory or criterion setting? Vision Research, 1998, 38, 557-572). Copyright © 2014 Elsevier Ltd. All rights reserved.

The interaction of glottal-pulse rate and vocal-tract length in judgements of speaker size, sex, and age

NASA Astrophysics Data System (ADS)

Smith, David R. R.; Patterson, Roy D.

2005-11-01

Glottal-pulse rate (GPR) and vocal-tract length (VTL) are related to the size, sex, and age of the speaker but it is not clear how the two factors combine to influence our perception of speaker size, sex, and age. This paper describes experiments designed to measure the effect of the interaction of GPR and VTL upon judgements of speaker size, sex, and age. Vowels were scaled to represent people with a wide range of GPRs and VTLs, including many well beyond the normal range of the population, and listeners were asked to judge the size and sex/age of the speaker. The judgements of speaker size show that VTL has a strong influence upon perceived speaker size. The results for the sex and age categorization (man, woman, boy, or girl) show that, for vowels with GPR and VTL values in the normal range, judgements of speaker sex and age are influenced about equally by GPR and VTL. For vowels with abnormal combinations of low GPRs and short VTLs, the VTL information appears to decide the sex/age judgement.

Nuclear axial currents in chiral effective field theory

DOE PAGES

Baroni, Alessandro; Girlanda, Luca; Pastore, Saori; ...

2016-01-11

Two-nucleon axial charge and current operators are derived in chiral effective field theory up to one loop. The derivation is based on time-ordered perturbation theory and accounts for cancellations between the contributions of irreducible diagrams and the contributions owing to nonstatic corrections from energy denominators of reducible diagrams. Ultraviolet divergencies associated with the loop corrections are isolated in dimensional regularization. The resulting axial current is finite and conserved in the chiral limit, while the axial charge requires renormalization. As a result, a complete set of contact terms for the axial charge up to the relevant order in the power countingmore » is constructed.« less

Three Dimensional Viscous Flow Field in an Axial Flow Turbine Nozzle Passage

NASA Technical Reports Server (NTRS)

Ristic, D.; Lakshminarayana, B.

1997-01-01

The objective of this investigation is experimental and computational study of three dimensional viscous flow field in the nozzle passage of an axial flow turbine stage. The nozzle passage flow field has been measured using a two sensor hot-wire probe at various axial and radial stations. In addition, two component LDV measurements at one axial station (x/c(sum m) = 0.56) were performed to measure the velocity field. Static pressure measurements and flow visualization, using a fluorescent oil technique, were also performed to obtain the location of transition and the endwall limiting streamlines. A three dimensional boundary layer code, with a simple intermittency transition model, was used to predict the viscous layers along the blade and endwall surfaces. The boundary layers on the blade surface were found to be very thin and mostly laminar, except on the suction surface downstream of 70% axial chord. Strong radial pressure gradient, especially close to the suction surface, induces strong cross flow components in the trailing edge regions of the blade. On the end-walls the boundary layers were much thicker, especially near the suction corner of the casing surface, caused by secondary flow. The secondary flow region near the suction-casing surface corner indicates the presence of the passage vortex detached from the blade surface. The corner vortex is found to be very weak. The presence of a closely spaced rotor downstream (20% of the nozzle vane chord) introduces unsteadiness in the blade passage. The measured instantaneous velocity signal was filtered using FFT square window to remove the periodic unsteadiness introduced by the downstream rotor and fans. The filtering decreased the free stream turbulence level from 2.1% to 0.9% but had no influence on the computed turbulence length scale. The computation of the three dimensional boundary layers is found to be accurate on the nozzle passage blade surfaces, away from the end-walls and the secondary flow region. On

Telomere length of the colonial coral Galaxea fascicularis at different developmental stages

NASA Astrophysics Data System (ADS)

Tsuta, H.; Hidaka, M.

2013-06-01

The ability to estimate coral age using soft tissue would be useful for population biology or aging studies on corals. In this study, we investigated whether telomere length can be used to estimate coral age. We applied single telomere length analysis to a colonial coral, Galaxea fascicularis, and estimated telomere lengths of specific coral chromosomes at different developmental stages. If the telomere shortened at each cell division, the telomere length of the coral would be longest in sperm and shortest in adult colonies. However, the mean telomere length of sperm, planula larvae, and polyps was approximately 4 kb, with no significant differences among the developmental stages. The telomerase restriction fragment (TRF) analysis also showed no significant difference in the mean TRF length among the developmental stages. Our results suggested that telomere length is maintained during developmental stages and that estimating the age of colonial coral based on telomere length may not be possible. However, our findings can be used to examine avoidance of aging and rejuvenation during regeneration and asexual reproduction in colonial corals.

Confined anterior cerebral artery infarction manifesting as isolated unilateral axial weakness.

PubMed

Honig, Asaf; Eliahou, Ruth; Auriel, Eitan

2017-02-15

We describe isolated unilateral axial weakness in three patients eventually diagnosed with anterior cerebral artery infarction (ACAI), a new clinical observation. Files of three ACAI patients (2 females, 1 male, ages 55-80) were retrospectively reviewed. All three presented to the ED with sudden unsteadiness. On initial neurological examination, all three patients manifested unilateral truncal deviation to the side contralateral to the weakness, even while seated. There was significant unilateral hypotonia due to substantial paravertebral weakness. None had pyramidal signs or increased limb tone. Speech, language, and cognitive performance were intact during admission examination. In all three patients, initial diffusion-weighted imaging (DWI) MRI showed small confined regions of restriction involving the posterolateral border of ACA territory; CT angiography was normal in one patient with a newly diagnosed atrial fibrillation but showed atherosclerotic vasculature with severe narrowing of the A3 segment of the ACA in two. Awareness of ACAI presenting as unilateral axial weakness is warranted. We suggest that optimal diagnostic management should include examination of axial tone. Ischemic involvement of distal ACA branches may herald a more extensive ACAI. Prompt diagnosis may enable thrombolysis or endovascular treatment, and blood pressure maintenance may allow adequate perfusion to damaged tissue. Copyright © 2016 Elsevier B.V. All rights reserved.

Minimal shortening of leukocyte telomere length across age groups in a cross-sectional study for carriers of a longevity-associated FOXO3 allele.

PubMed

Davy, Philip M C; Willcox, D Craig; Shimabukuro, Michio; Donlon, Timothy A; Torigoe, Trevor; Suzuki, Makoto; Higa, Moritake; Masuzaki, Hiroaki; Sata, Masataka; Chen, Randi; Murkofsky, Rachel; Morris, Brian J; Lim, Eunjung; Allsopp, Richard C; Willcox, Bradley J

2018-04-21

FOXO3 is one of the most prominent genes demonstrating a consistently reproducible genetic association with human longevity. The mechanisms by which these individual gene variants confer greater organismal lifespan are not well understood. We assessed the effect of longevity-associated FOXO3 alleles on age-related leukocyte telomere dynamics in a cross-sectional study comprising of samples from 121 healthy Okinawan-Japanese donors aged 21-95 years. We found that telomere length for carriers of the longevity associated allele of FOXO3 single nucleotide polymorphism rs2802292 displayed no significant correlation with age, an effect that was most pronounced in older (>50) participants. This is the first validated longevity gene variant identified to date showing an association with negligible loss of telomere length with age in humans in a cross sectional study. Reduced telomere attrition may be a key mechanism for the longevity-promoting effect of the FOXO3 genotype studied.

Heat transfer analysis of the Bridgman-Stockbarger configuration for crystal growth. Part 1: Analytical treatment of the axial temperature distribution

NASA Technical Reports Server (NTRS)

Jasinski, T. J.; Rohsenow, W. M.; Witt, A. F.

1982-01-01

All first order effects on the axial temperature distribution in a solidifying charge in a Bridgman-Stockbarger configuration for crystal growth are analyzed on the basis of a one dimensional model whose validity can be verified through comparison with published finite difference ana;uses of two dimensional models. The model presented includes an insulated region between axially aligned heat pipes and considers the effects of charge diameter, charge motion, thickness, and thermal conductivity of a confining crucible, thermal conductivity change at the crystal-melt interface, generation of latent heat at the interface, and finite charge length. Results are primarily given in analytical form and can be used without recourse to computer work for both improve furnace design and optimization of growth conditions in a given thermal configuration.

Best Stent Length Predicted by Simple CT Measurement Rather than Patient Height.

PubMed

Barrett, Keith; Foell, Kirsten; Lantz, Andrea; Ordon, Michael; Lee, Jason Y; Pace, Kenneth T; Honey, R John D'A

2016-09-01

Ureteral stent length is important, as stents that are too long might worsen symptoms and too short are at higher risk of migration. The purpose of this study was to determine if patient or radiologic parameters correlate with directly measured ureteral length and if directly measured ureteral length predicts proper stent positioning. During stent placement, ureteral length (ureteropelvic junction to ureterovesical junction distance) was directly measured by endoscopically viewing a ureteral catheter (with 1-cm marking) emanating from the ureteral orifice. A 22, 24, or 26 cm stent was chosen to be closest to the measured ureteral length. For ureters >26 cm, a 26 cm stent was chosen. Ends of an "ideally positioned" stent were fully curled in the renal pelvis and bladder, without crossing the bladder midline. Rates of ideal stent position were compared between patients with matching stent and ureteral lengths and those with stent lengths differing by ≥1 cm (mismatched). The measured ureteral length was correlated with patient height, L1-L5 height, and length measured on CT. Fifty-nine ureters from 57 patients were included. Height was reasonably correlated with L1-L5 height (Spearman correlation coefficient [rho] = 0.79), although both were poorly correlated with directly measured ureteral length (rho = 0.18 for height and 0.32 for lumbar height). Ureteral lengths measured on CT correlated well with direct measurement (rho = 0.63 for axial cuts and rho = 0.64 for coronal cuts). Matched stent length was associated with higher rates of ideal stent position than mismatched (100% vs 70.9%, p = 0.006). CT measurements, rather than height, correlate well with measured length and could be used to choose the appropriate stent length. Stents matching directly measured ureteral lengths are associated with high rates of ideal stent position.

Facilitating higher-fidelity simulations of axial compressor instability and other turbomachinery flow conditions

NASA Astrophysics Data System (ADS)

Herrick, Gregory Paul

The quest to accurately capture flow phenomena with length-scales both short and long and to accurately represent complex flow phenomena within disparately sized geometry inspires a need for an efficient, high-fidelity, multi-block structured computational fluid dynamics (CFD) parallel computational scheme. This research presents and demonstrates a more efficient computational method by which to perform multi-block structured CFD parallel computational simulations, thus facilitating higher-fidelity solutions of complicated geometries (due to the inclusion of grids for "small'' flow areas which are often merely modeled) and their associated flows. This computational framework offers greater flexibility and user-control in allocating the resource balance between process count and wall-clock computation time. The principal modifications implemented in this revision consist of a "multiple grid block per processing core'' software infrastructure and an analytic computation of viscous flux Jacobians. The development of this scheme is largely motivated by the desire to simulate axial compressor stall inception with more complete gridding of the flow passages (including rotor tip clearance regions) than has been previously done while maintaining high computational efficiency (i.e., minimal consumption of computational resources), and thus this paradigm shall be demonstrated with an examination of instability in a transonic axial compressor. However, the paradigm presented herein facilitates CFD simulation of myriad previously impractical geometries and flows and is not limited to detailed analyses of axial compressor flows. While the simulations presented herein were technically possible under the previous structure of the subject software, they were much less computationally efficient and thus not pragmatically feasible; the previous research using this software to perform three-dimensional, full-annulus, time-accurate, unsteady, full-stage (with sliding

Characterization of Femoral Component Initial Stability and Cortical Strain in a Reduced Stem-Length Design.

PubMed

Small, Scott R; Hensley, Sarah E; Cook, Paige L; Stevens, Rebecca A; Rogge, Renee D; Meding, John B; Berend, Michael E

2017-02-01

Short-stemmed femoral components facilitate reduced exposure surgical techniques while preserving native bone. A clinically successful stem should ideally reduce risk for stress shielding while maintaining adequate primary stability for biological fixation. We asked (1) how stem-length changes cortical strain distribution in the proximal femur in a fit-and-fill geometry and (2) if short-stemmed components exhibit primary stability on par with clinically successful designs. Cortical strain was assessed via digital image correlation in composite femurs implanted with long, medium, and short metaphyseal fit-and-fill stem designs in a single-leg stance loading model. Strain was compared to a loaded, unimplanted femur. Bone-implant micromotion was then compared with reduced lateral shoulder short stem and short tapered-wedge designs in cyclic axial and torsional testing. Femurs implanted with short-stemmed components exhibited cortical strain response most closely matching that of the intact femur model, theoretically reducing the potential for proximal stress shielding. In micromotion testing, no difference in primary stability was observed as a function of reduced stem length within the same component design. Our findings demonstrate that within this fit-and-fill stem design, reduction in stem length improved proximal cortical strain distribution and maintained axial and torsional stability on par with other stem designs in a composite femur model. Short-stemmed implants may accommodate less invasive surgical techniques while facilitating more physiological femoral loading without sacrificing primary implant stability. Copyright © 2016 Elsevier Inc. All rights reserved.

Trunk axial rotation in baseball pitching and batting.

PubMed

Fleisig, Glenn S; Hsu, Wellington K; Fortenbaugh, Dave; Cordover, Andrew; Press, Joel M

2013-11-01

The purpose of this study was to quantify trunk axial rotation and angular acceleration in pitching and batting of elite baseball players. Healthy professional baseball pitchers (n = 40) and batters (n = 40) were studied. Reflective markers attached to each athlete were tracked at 240 Hz with an eight-camera automated digitizing system. Trunk axial rotation was computed as the angle between the pelvis and the upper trunk in the transverse plane. Trunk angular acceleration was the second derivative of axial rotation. Maximum trunk axial rotation (55 +/- 6 degrees) and angular acceleration (11,600 +/- 3,100 degrees/s2) in pitching occurred before ball release, approximately at the instant the front foot landed. Maximum trunk axial rotation (46 +/- 9 degrees) and angular acceleration (7,200 +/- 2,800 degrees/s2) in batting occurred in the follow-through after ball contact. Thus, the most demanding instant for the trunk and spine was near front foot contact for pitching and after ball contact for batting.

Spiral vortices and Taylor vortices in the annulus between rotating cylinders and the effect of an axial flow.

PubMed

Hoffmann, Ch; Lücke, M; Pinter, A

2004-05-01

We present numerical simulations of vortices that appear via primary bifurcations out of the unstructured circular Couette flow in the Taylor-Couette system with counter rotating as well as with corotating cylinders. The full, time dependent Navier Stokes equations are solved with a combination of a finite difference and a Galerkin method for a fixed axial periodicity length of the vortex patterns and for a finite system of aspect ratio 12 with rigid nonrotating ends in a setup with radius ratio eta=0.5. Differences in structure, dynamics, symmetry properties, bifurcation, and stability behavior between spiral vortices with azimuthal wave numbers M=+/-1 and M=0 Taylor vortices are elucidated and compared in quantitative detail. Simulations in axially periodic systems and in finite systems with stationary rigid ends are compared with experimental spiral data. In a second part of the paper we determine how the above listed properties of the M=-1, 0, and 1 vortex structures are changed by an externally imposed axial through flow with Reynolds numbers in the range -40< or =Re< or =40. Among other things we investigate when left handed or right handed spirals or toroidally closed vortices are preferred.

Cyclic axial-torsional deformation behavior of a cobalt-base superalloy

NASA Technical Reports Server (NTRS)

Bonacuse, Peter J.; Kalluri, Sreeramesh

1992-01-01

Multiaxial loading, especially at elevated temperature, can cause the inelastic response of a material to differ significantly from that predicted by simple flow rules, i.e., von Mises or Tresca. To quantify some of these differences, the cyclic high-temperature, deformation behavior of a wrought cobalt-based superalloy, Haynes 188, is investigated under combined axial and torsional loads. Haynes 188 is currently used in many aerospace gas turbine and rocket engine applications, e.g., the combustor liner for the T800 turboshaft engine for the RAH-66 Comanche helicopter and the liquid oxygen posts in the main injector of the space shuttle main engine. The deformation behavior of this material is assessed through the examination of hysteresis loops generated from a biaxial fatigue test program. A high-temperature axial, torsional, and combined axial-torsional fatigue data base has been generated on Haynes 188 at 760 C. Cyclic loading tests have been conducted on uniform gauge section tubular specimens in a servohydraulic axial-torsional test rig. Test control and data acquisition were accomplished with a minicomputer. In this paper, the cyclic hardening characteristics and typical hysteresis loops in the axial stress versus axial strain, shear stress versus engineering shear strain, axial strain versus engineering shear strain, and axial stress versus shear stress spaces are presented for cyclic, in-phase and out-of-phase, axial torsional tests. For in-phase tests three different values of the proportionality constant, lambda (ratio of engineering shear strain amplitude to axial strain amplitude), are examined, viz., 0.86, 1.73, and 3.46. In the out-of-phase tests, three different values of the phase angle, phi (between the axial and engineering shear strain waveforms), are studied, viz., 30, 60, and 90 deg with lambda = 1.73. The cyclic hardening behaviors of all the tests conducted on Haynes 188 at 760 C are evaluated using the von Mises equivalent stress

Nonuniformity of axial and circumferential remodeling of large coronary veins in response to ligation.

PubMed

Choy, Jenny Susana; Dang, Quang; Molloi, Sabee; Kassab, Ghassan S

2006-04-01

The pressure-induced remodeling of coronary veins is important in coronary venous retroperfusion. Our hypothesis is that the response of the large coronary veins to pressure overload will depend on the degree of myocardial support. Eleven normal Yorkshire swine from either sex, weighing 31-39 kg, were studied. Five pigs underwent ligation of the left anterior descending (LAD) vein, and six served as sham-operated controls. The ligation of the coronary vein caused an increase in pressure intermediate to arterial and venous values. After 2 wk of ligation, the animals were euthanized and the coronary vessels were perfusion-fixed with glutaraldehyde. The LAD vein was sectioned, and detailed morphometric measurements were made along its length from the point of ligation near the base down to the apex of the heart. The structural remodeling of the vein was circumferentially nonuniform because the vein is partially embedded in the myocardium; it was also axially nonuniform because it is tethered to the myocardium to different degrees along its axial length. The wall area was significantly larger in the experimental group, whereas luminal area in the proximal LAD vein was significantly smaller in the same group compared with sham-operated controls. The wall thickness-to-radius ratio was also significantly larger in the experimental group in proportion to the increase in pressure. The major conclusion of this study is that the response of the vein depends on the local wall stress, which is, in part, determined by the surrounding tissue. Furthermore, the geometric remodeling of the coronary vein restores the circumferential stress to the homeostatic value.

Axial field shaping under high-numerical-aperture focusing

NASA Astrophysics Data System (ADS)

Jabbour, Toufic G.; Kuebler, Stephen M.

2007-03-01

Kant reported [J. Mod. Optics47, 905 (2000)] a formulation for solving the inverse problem of vector diffraction, which accurately models high-NA focusing. Here, Kant's formulation is adapted to the method of generalized projections to obtain an algorithm for designing diffractive optical elements (DOEs) that reshape the axial point-spread function (PSF). The algorithm is applied to design a binary phase-only DOE that superresolves the axial PSF with controlled increase in axial sidelobes. An 11-zone DOE is identified that axially narrows the PSF central lobe by 29% while maintaining the sidelobe intensity at or below 52% of the peak intensity. This DOE could improve the resolution achievable in several applications without significantly complicating the optical system.

Effect of segmented electrode length on the performances of Hall thruster

NASA Astrophysics Data System (ADS)

Duan, Ping; Chen, Long; Liu, Guangrui; Bian, Xingyu; Yin, Yan

2016-09-01

The influences of the low-emissive graphite segmented electrode placed near the channel exit on the discharge characteristics of Hall thruster are studied using the particle-in-cell method. A two-dimensional physical model is established according to the Hall thruster discharge channel configuration. The effects of electrode length on potential, ion density, electron temperature, ionization rate and discharge current are investigated. It is found that, with the increasing of segmented electrode length, the equipotential lines bend towards the channel exit, and approximately parallel to the wall at the channel surface, radial velocity and radial flow of ions are increased, and the electron temperature is also enhanced. Due to the conductive characteristic of electrodes, the radial electric field and the axial electron conductivity near the wall are enhanced, and the probability of the electron-atom ionization is reduced, which leads to the degradation of ionization rate in discharge channel. However, the interaction between electrons and the wall enhances the near wall conductivity, therefore the discharge current grows along with the segmented electrode length, and the performance of the thruster is also affected.

Relationship Between Humeral Retroversion and Length of Baseball Career Before the Age of 16 Years.

PubMed

Nakase, Chihiro; Mihata, Teruhisa; Itami, Yasuo; Takeda, Atsushi; Neo, Masashi

2016-09-01

Humeral retroversion physiologically decreases during growth. However, in throwing athletes, the external forces caused by repetitive throwing are thought to increase humeral retroversion on the dominant side compared with that on the nondominant side. To investigate the correlation between humeral retroversion and length of baseball career before age 16 years. Cross-sectional study; Level of evidence, 3. A total of 112 high school baseball players (32 pitchers and 80 position players) with a mean age of 15.6 years (range, 15-16 years) were enrolled in the study. All participants completed questionnaires regarding their player position and the age when they started baseball and were given physical examinations. Shoulder range of motion and humeral retroversion were assessed on the dominant and nondominant sides. Humeral retroversion (rotation angle of the proximal humerus relative to the distal humerus) was measured ultrasonographically. Humeral retroversion was significantly greater on the dominant side than on the nondominant side in both pitchers (P < .0001) and position players (P = .0005). The side-to-side difference in humeral retroversion in pitchers (13.9° ± 11.2°) was significantly greater than that in position players (9.0° ± 11.1°, P = .0361). In pitchers, there was a significant negative correlation between humeral retroversion and the age at which the players had started baseball (P = .033, β = -2.494). These results suggest that humeral retroversion increases with decreasing age at commencement of a baseball career before age 16 years in pitchers. © 2016 The Author(s).

Universality of modulation length and time exponents.

PubMed

Chakrabarty, Saurish; Dobrosavljević, Vladimir; Seidel, Alexander; Nussinov, Zohar

2012-10-01

We study systems with a crossover parameter λ, such as the temperature T, which has a threshold value λ(*) across which the correlation function changes from exhibiting fixed wavelength (or time period) modulations to continuously varying modulation lengths (or times). We introduce a hitherto unknown exponent ν(L) characterizing the universal nature of this crossover and compute its value in general instances. This exponent, similar to standard correlation length exponents, is obtained from motion of the poles of the momentum (or frequency) space correlation functions in the complex k-plane (or ω-plane) as the parameter λ is varied. Near the crossover (i.e., for λ→λ(*)), the characteristic modulation wave vector K(R) in the variable modulation length "phase" is related to that in the fixed modulation length "phase" q via |K(R)-q|[proportionality]|T-T(*)|(νL). We find, in general, that ν(L)=1/2. In some special instances, ν(L) may attain other rational values. We extend this result to general problems in which the eigenvalue of an operator or a pole characterizing general response functions may attain a constant real (or imaginary) part beyond a particular threshold value λ(*). We discuss extensions of this result to multiple other arenas. These include the axial next-nearest-neighbor Ising (ANNNI) model. By extending our considerations, we comment on relations pertaining not only to the modulation lengths (or times), but also to the standard correlation lengths (or times). We introduce the notion of a Josephson time scale. We comment on the presence of aperiodic "chaotic" modulations in "soft-spin" and other systems. These relate to glass-type features. We discuss applications to Fermi systems, with particular application to metal to band insulator transitions, change of Fermi surface topology, divergent effective masses, Dirac systems, and topological insulators. Both regular periodic and glassy (and spatially chaotic behavior) may be found in

Size-dependent elastic/inelastic behavior of enamel over millimeter and nanometer length scales.

PubMed

Ang, Siang Fung; Bortel, Emely L; Swain, Michael V; Klocke, Arndt; Schneider, Gerold A

2010-03-01

The microstructure of enamel like most biological tissues has a hierarchical structure which determines their mechanical behavior. However, current studies of the mechanical behavior of enamel lack a systematic investigation of these hierarchical length scales. In this study, we performed macroscopic uni-axial compression tests and the spherical indentation with different indenter radii to probe enamel's elastic/inelastic transition over four hierarchical length scales, namely: 'bulk enamel' (mm), 'multiple-rod' (10's microm), 'intra-rod' (100's nm with multiple crystallites) and finally 'single-crystallite' (10's nm with an area of approximately one hydroxyapatite crystallite). The enamel's elastic/inelastic transitions were observed at 0.4-17 GPa depending on the length scale and were compared with the values of synthetic hydroxyapatite crystallites. The elastic limit of a material is important as it provides insights into the deformability of the material before fracture. At the smallest investigated length scale (contact radius approximately 20 nm), elastic limit is followed by plastic deformation. At the largest investigated length scale (contact size approximately 2 mm), only elastic then micro-crack induced response was observed. A map of elastic/inelastic regions of enamel from millimeter to nanometer length scale is presented. Possible underlying mechanisms are also discussed. (c) 2009 Elsevier Ltd. All rights reserved.

Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.

PubMed

Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki

2013-07-29

We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.

Acoustic performance of low pressure axial fan rotors with different blade chord length and radial load distribution

NASA Astrophysics Data System (ADS)

Carolus, Thomas

The paper examines the acoustic and aerodynamic performance of low-pressure axial fan rotors with a hub/tip ratio of 0.45. Six rotors were designed for the same working point by means of the well-known airfoil theory. The condition of an equilibrium between the static pressure gradient and the centrifugal forces is maintained. All rotors have unequally spaced blades to diminish tonal noise. The rotors are tested in a short cylindrical housing without guide vanes. All rotors show very similar flux-pressure difference characteristics. The peak efficiency and the noise performance is considerably influenced by the chosen blade design. The aerodynamically and acoustically optimal rotor is the one with the reduced load at the hub and increased load in the tip region under satisfied equilibrium conditions. It runs at the highest aerodynamic efficiency, and its noise spectrum is fairly smooth. The overall sound pressure level of this rotor is up to 8 dB (A) lower compared to the other rotors under consideration.

Retinal nerve fiber layer measurements by scanning laser polarimetry with enhanced corneal compensation in healthy subjects.

PubMed

Rao, Harsha L; Venkatesh, Chirravuri R; Vidyasagar, Kelli; Yadav, Ravi K; Addepalli, Uday K; Jude, Aarthi; Senthil, Sirisha; Garudadri, Chandra S

2014-12-01

To evaluate the (i) effects of biological (age and axial length) and instrument-related [typical scan score (TSS) and corneal birefringence] parameters on the retinal nerve fiber layer (RNFL) measurements and (ii) repeatability of RNFL measurements with the enhanced corneal compensation (ECC) protocol of scanning laser polarimetry (SLP) in healthy subjects. In a cross-sectional study, 140 eyes of 73 healthy subjects underwent RNFL imaging with the ECC protocol of SLP. Linear mixed modeling methods were used to evaluate the effects of age, axial length, TSS, and corneal birefringence on RNFL measurements. One randomly selected eye of 48 subjects from the cohort underwent 3 serial scans during the same session to determine the repeatability. Age significantly influenced all RNFL measurements. RNFL measurements decreased by 1 µm for every decade increase in age. TSS affected the overall average RNFL measurement (β=-0.62, P=0.003), whereas residual anterior segment retardance affected the superior quadrant measurement (β=1.14, P=0.01). Axial length and corneal birefringence measurements did not influence RNFL measurements. Repeatability, as assessed by the coefficient of variation, ranged between 1.7% for the overall average RNFL measurement and 11.4% for th nerve fiber indicator. Age significantly affected all RNFL measurements with the ECC protocol of SLP, whereas TSS and residual anterior segment retardance affected the overall average and the superior average RNFL measurements, respectively. Axial length and corneal birefringence measurements did not influence any RNFL measurements. RNFL measurements had good intrasession repeatability. These results are important while evaluating the change in structural measurements over time in glaucoma patients.

Allometric relationships among body mass, MUZZLE-tail length, and tibia length during the growth of Wistar rats.

PubMed

Santiago, Hildemberg Agostinho Rocha de; De Pierro, Lucas Rodolfo; Reis, Rafael Menezes; Caluz, Antônio Gabriel Ricardo Engracia; Ribeiro, Victor Barbosa; Volpon, José Batista

2015-11-01

To investigate allometric relationships among body mass (BM), muzzle-tail length (MTL), and tibia length (TL) in Wistar rats and establish their growth rate change parameters. Eighteen male and 18 female Wistar rats were studied from the 3rd to the 21st week of age. BM, MTL, and TL were measured daily, and relative growth was compared using allometry. A positive correlation between BM and MTL (p<0.05) and BM and TL (p<0.05) was observed. Males and females showed comparable curves; however, females had turning points at a younger age. The allometric relationship between BM and MTL presented a regular increase until reaching a mass of 351 g (males) and 405 g (females). BM and TL showed an initial increase until 185 g (males) and 182 g (females), and then reached a plateau that finished at 412 g (males) and 334 g (females), to display another increase. The allometric relationship of body mass with animal length and tibia length was comparable for male and female rats, with female rats maturing earlier. Animal longitudinal growth occurred in a single stage. In contrast, tibia length depicted two stages of accelerated growth with an intermediate period of deceleration.

Early brain enlargement and elevated extra-axial fluid in infants who develop autism spectrum disorder.

PubMed

Shen, Mark D; Nordahl, Christine W; Young, Gregory S; Wootton-Gorges, Sandra L; Lee, Aaron; Liston, Sarah E; Harrington, Kayla R; Ozonoff, Sally; Amaral, David G

2013-09-01

Prospective studies of infants at risk for autism spectrum disorder have provided important clues about the early behavioural symptoms of autism spectrum disorder. Diagnosis of autism spectrum disorder, however, is not currently made until at least 18 months of age. There is substantially less research on potential brain-based differences in the period between 6 and 12 months of age. Our objective in the current study was to use magnetic resonance imaging to identify any consistently observable brain anomalies in 6-9 month old infants who would later develop autism spectrum disorder. We conducted a prospective infant sibling study with longitudinal magnetic resonance imaging scans at three time points (6-9, 12-15, and 18-24 months of age), in conjunction with intensive behavioural assessments. Fifty-five infants (33 'high-risk' infants having an older sibling with autism spectrum disorder and 22 'low-risk' infants having no relatives with autism spectrum disorder) were imaged at 6-9 months; 43 of these (27 high-risk and 16 low-risk) were imaged at 12-15 months; and 42 (26 high-risk and 16 low-risk) were imaged again at 18-24 months. Infants were classified as meeting criteria for autism spectrum disorder, other developmental delays, or typical development at 24 months or later (mean age at outcome: 32.5 months). Compared with the other two groups, infants who developed autism spectrum disorder (n = 10) had significantly greater extra-axial fluid at 6-9 months, which persisted and remained elevated at 12-15 and 18-24 months. Extra-axial fluid is characterized by excessive cerebrospinal fluid in the subarachnoid space, particularly over the frontal lobes. The amount of extra-axial fluid detected as early as 6 months was predictive of more severe autism spectrum disorder symptoms at the time of outcome. Infants who developed autism spectrum disorder also had significantly larger total cerebral volumes at both 12-15 and 18-24 months of age. This is the first magnetic

Weight, Length, and Body Mass Index Growth of Children Under 2 Years of Age With Cleft Lip and Palate.

PubMed

Miranda, Gabriela Serrano; Marques, Ilza Lazarini; de Barros, Suely Prietto; Arena, Eliane Petean; de Souza, Luiz

2016-05-01

To study the growth of length-for-age (L/A), weight-for-age (W/A), and body mass index (BMI) of children with cleft lip and palate receiving a normal diet; to establish specific growth curves for children with cleft palate with or without cleft lip (CLP/ICP) who had not undergone palatoplasty and for children with isolated cleft lip (ICL); and to assess if CLP/ICP growth differed from ICL growth and if CLP/ICP and ICL growth differed from growth for typical children. Prospective and cross-sectional study. Hospital for Rehabilitation of Craniofacial Anomalies, Bauru, São Paulo, Brazil. Weight and length of 381 children with cleft lip and palate and who were younger than 2 years were recorded and used to calculate W/A, L/A, and BMI growth curves. The 2006 World Health Organization growth charts were used as a reference for typical children. All children received a normal diet for age. Children with CLP/ICP had median W/A and BMI growth curves below growth curves for typical children but showed spontaneous recovery starting at approximately 5 months of age, even with nonoperated cleft palate. Children with ICL had growth similar to that of typical children. Children with CLP/ICP, who initially had W/A and BMI values less than those of the ICL group, had W/A and BMI equal to or higher than the ICL group after 9 months of age. Children with CLP/ICP had impaired W/A and BMI growth with spontaneous recovery starting early in childhood. This study established specific W/A, BMI, and L/A growth curves for children with cleft lip and palate.

Prenatal factors associated with birth weight and length and current nutritional status of hospitalized children aged 4-24 months.

PubMed

Mariante Giesta, Juliana; Ramón da Rosa, Suélen; Moura Pessoa, Juliana Salino; Lúcia Bosa, Vera

2015-06-01

The objective of the present study was to investigate the associations of prenatal factors with birth weight and length, as well as current nutritional status, of children hospitalized in southern Brazil. We conducted a cross-sectional study of 300 child-mother pairs. Children were between 4 and 24 months old. They were at the inpatient unit or pediatric emergency department of the Hospital de Clínicas de Porto Alegre. Anthropometric data were collected, and a questionnaire on gestational data was answered by the children's mothers. Maternal variables of interest were: prepregnancy body mass index (BMI), gestational weight gain, smoking and/or use of alcohol, use of illicit drugs, gestational diabetes and/ or high blood pressure. Children's variables of interest were: sex, gestational age, birth weight (BW) and birth length (BL), and current anthropometric data [body mass index for age (BMI/A), height for age (H/A), and weight for age (W/A)]. The gestational weight gain and smoking were associated with BW. We also found that H/A was associated with BW and BL, W/A was associated with BW, and BMI/A was associated with BL. The gestational weight gain was associated with BL, diabetes was associated with BW and BL, and high blood pressure was associated with low height in the first two years of life. We concluded that prenatal factors may have an influence on both BW and BL, causing the birth of small and large for gestational age children, and thus affecting their growth rate during the first years of life. Copyright AULA MEDICA EDICIONES 2014. Published by AULA MEDICA. All rights reserved.

The distribution of deformation in parallel fault-related folds with migrating axial surfaces: comparison between fault-propagation and fault-bend folding

NASA Astrophysics Data System (ADS)

Salvini, Francesco; Storti, Fabrizio

2001-01-01

In fault-related folds that form by axial surface migration, rocks undergo deformation as they pass through axial surfaces. The distribution and intensity of deformation in these structures has been impacted by the history of axial surface migration. Upon fold initiation, unique dip panels develop, each with a characteristic deformation intensity, depending on their history. During fold growth, rocks that pass through axial surfaces are transported between dip panels and accumulate additional deformation. By tracking the pattern of axial surface migration in model folds, we predict the distribution of relative deformation intensity in simple-step, parallel fault-bend and fault-propagation anticlines. In both cases the deformation is partitioned into unique domains we call deformation panels. For a given rheology of the folded multilayer, deformation intensity will be homogeneously distributed in each deformation panel. Fold limbs are always deformed. The flat crests of fault-propagation anticlines are always undeformed. Two asymmetric deformation panels develop in fault-propagation folds above ramp angles exceeding 29°. For lower ramp angles, an additional, more intensely-deformed panel develops at the transition between the crest and the forelimb. Deformation in the flat crests of fault-bend anticlines occurs when fault displacement exceeds the length of the footwall ramp, but is never found immediately hinterland of the crest to forelimb transition. In environments dominated by brittle deformation, our models may serve as a first-order approximation of the distribution of fractures in fault-related folds.

Axial forces in centrifugal compressor couplings

NASA Astrophysics Data System (ADS)

Ivanov, A. N.; Ivanov, N. M.; Yun, V. K.

2017-08-01

The article presents the results of the theoretical and experimental investigation of axial forces arising in the toothed and plate couplings of centrifugal compressor shaft lines. Additional loads on the thrust bearing are considered that can develop in the toothed couplings as a result of coupled rotors misalignment. Design relationships to evaluate the level of axial forces and recommendations for their reduction in the operating conditions are given.

Numerical investigation on the self-induced unsteadiness in tip leakage flow of a micro-axial fan rotor

NASA Astrophysics Data System (ADS)

Chen, Jinxin; Lai, Huanxin

2015-06-01

The self-induced unsteadiness in tip leakage flow (TLF) of a micro-axial fan rotor is numerically studied by solvingReynolds-averaged Navier-Stokes equations. The micro-axial fan, which is widely used in cooling systems of electronic devices, has a tip clearance of 6% of the axial chord length of the blade. At the design rotation speed, four cases near the peak efficiency point (PEP) with self-induced unsteadiness and four steady cases which have much weaker pressure fluctuations are investigated Using the "interface" separating the incoming main flow and the TLF defined by Du et al. [1], an explanation based on the propagation of the low energy spot and its multi-passing through the high gradient zone of the relativetotal pressure, is proposed to clarify the originating mechanism of the unsteadiness. At the operating points near the PEP, the main flow is weaker than the TLF and the interface moves upstream. The low energy spot which propagates along in the close behind of the interface has opportunity to circulate in the circumferential direction and passes through the sensitive interfaces several times, a slight perturbation therefore may be magnified significantlyand develops into the self-induced unsteadiness. The explanation is demonstrated by numerical results

Circulating leukocyte telomere length is highly heritable among families of Arab descent

PubMed Central

2012-01-01

Background Telomere length, an indicator of ageing and longevity, has been correlated with several biomarkers of cardiometabolic disease in both Arab children and adults. It is not known, however, whether or not telomere length is a highly conserved inheritable trait in this homogeneous cohort, where age-related diseases are highly prevalent. As such, the aim of this study was to address the inheritability of telomere length in Saudi families and the impact of cardiometabolic disease biomarkers on telomere length. Methods A total of 119 randomly selected Saudi families (123 adults and 131 children) were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for routine analyses of fasting glucose and lipid profile. Leukocyte telomere length was determined using quantitative real time PCR. Results Telomere length was highly heritable as assessed by a parent-offspring regression [h2 = 0.64 (p = 0.0006)]. Telomere length was modestly associated with BMI (R2 0.07; p-value 0.0087), total cholesterol (R2 0.08; p-value 0.0033), and LDL-cholesterol (R2 0.15; p-value 3 x 10-5) after adjustments for gender, age and age within generation. Conclusion The high heritability of telomere length in Arab families, and the associations of telomere length with various cardiometabolic parameters suggest heritable genetic fetal and/or epigenetic influences on the early predisposition of Arab children to age-related diseases and accelerated ageing. PMID:22606980

Circulating leukocyte telomere length is highly heritable among families of Arab descent.

PubMed

Al-Attas, Omar S; Al-Daghri, Nasser M; Alokail, Majed S; Alkharfy, Khalid M; Alfadda, Assim A; McTernan, Philip; Gibson, Greg C; Sabico, Shaun B; Chrousos, George P

2012-05-18

Telomere length, an indicator of ageing and longevity, has been correlated with several biomarkers of cardiometabolic disease in both Arab children and adults. It is not known, however, whether or not telomere length is a highly conserved inheritable trait in this homogeneous cohort, where age-related diseases are highly prevalent. As such, the aim of this study was to address the inheritability of telomere length in Saudi families and the impact of cardiometabolic disease biomarkers on telomere length. A total of 119 randomly selected Saudi families (123 adults and 131 children) were included in this cross-sectional study. Anthropometrics were obtained and fasting blood samples were taken for routine analyses of fasting glucose and lipid profile. Leukocyte telomere length was determined using quantitative real time PCR. Telomere length was highly heritable as assessed by a parent-offspring regression [h2 = 0.64 (p = 0.0006)]. Telomere length was modestly associated with BMI (R(2) 0.07; p-value 0.0087), total cholesterol (R(2) 0.08; p-value 0.0033), and LDL-cholesterol (R(2) 0.15; p-value 3 x 10(-5)) after adjustments for gender, age and age within generation. The high heritability of telomere length in Arab families, and the associations of telomere length with various cardiometabolic parameters suggest heritable genetic fetal and/or epigenetic influences on the early predisposition of Arab children to age-related diseases and accelerated ageing.

Angular and axial deformities of the legs of children.

PubMed

McDonough, M W

1984-12-01

Age is often a determining factor in establishing a treatment program for these axial and angular problems. As can be seen, the deformities of torsion are noticeable from early life. Any tibial torsion should be treated early, but an excessive medial range of motion in the infant leg with a corresponding adequate lateral range of motion of the limb may be cautiously observed. Medial femoral torsion is a normal early finding in the infant thigh. The problem becomes evident as the child matures without the corresponding reduction in femoral torsion, leading to a persistence of fetal or infantile alignment. The gait consequences are usually noticed at 4 to 8 years of age. The angular changes generally are a delayed finding noticed in stance. The bowleg may be associated with marked tibial torsion and picked up early but the Blount's patient has been traditionally definable at 2 years of age. Levin and Drennan may hasten the time of diagnosis with their radiographic criteria. Knock-knee is an alignment disturbance noticed during the early to mid-childhood years, age 4 to 8 years. The diagnosis is important, differentiating physiologic from torsion-related deformities, and treatment, if warranted, should not be delayed. Generally the earlier these problems are discovered, the more optimistic the prognosis. Since the pediatric limb is in a constant state of transition, there will be a perpetual argument as to the need or efficacy of various approaches to the problems of knock-knee and bowleg. If observation is the treatment of choice, the percentage of cases which go on to osteotomies and epiphyseal stapling will continue. For those with axial or angular deformities, degenerative arthritis of the knee may be forthcoming. Swanson, Greene, and Allis warned of problems becoming "unphysiologic." If we consider the epiphyseal malleability, not only to deformity but to correction, we can appreciate Lenoir's comment of "every day the problem goes untreated is a golden

Determination of Yield and Flow Surfaces for Inconel 718 Under Axial-Torsional Loading at Temperatures Up to 649 C

NASA Technical Reports Server (NTRS)

Gil, Christopher M.

1998-01-01

An experimental program to determine flow surfaces has been established and implemented for solution annealed and aged IN718. The procedure involved subjecting tubular specimens to various ratios of axial-torsional stress at temperatures between 23 and 649 C and measuring strain with a biaxial extensometer. Each stress probe corresponds to a different direction in stress space, and unloading occurs when a 30 microstrain (1 micro eplison = 10(exp -6) mm/mm) offset is detected. This technique was used to map out yield loci in axial-torsional stress space. Flow surfaces were determined by post-processing the experimental data to determine the inelastic strain rate components. Surfaces of constant inelastic strain rate (SCISRS) and surfaces of constant inelastic power (SCIPS) were mapped out in the axial-shear stress plane. The von Mises yield criterion appeared to closely fit the initial loci for solutioned IN718 at 23 C. However, the initial loci for solutioned IN718 at 371 and 454 C, and all of the initial loci for aged IN718 were offset in the compression direction. Subsequent loci showed translation, distortion, and for the case of solutioned IN718, a slight cross effect. Aged IN718 showed significantly more hardening behavior than solutioned IN718.

Behaviour of axially and eccentrically loaded short columns reinforced with GFRP bars

NASA Astrophysics Data System (ADS)

Sreenath, S.; Balaji, S.; Saravana Raja Mohan, K.

2017-07-01

The corrosion of steel reinforcing bars is a predominant factor in limiting the life expectancy of Reinforced Cement Concrete (RCC) structures. Corrosion resistant Fibre Reinforced Polymer (FRP) bars can be an effective alternative to steel bars in this context. Recent investigations reported the flexural behaviour of RCC beams reinforced with Glass Fibre Reinforced Polymer (GFRP) bars. This study is meant to investigate the suitability of Sand Coated GFRP reinforcement bars in short square columns which when loaded axially and loaded with a minimum eccentricity. Standard tests to assess mechanical properties of GFRP bars and pullout test to quantify the bond strength between the bars and concrete were conducted. GFRP reinforced column specimens with a cross-sectional dimension of 100mm X 100mm and of length 1000mm were cast and tested under axial and eccentric loading. The assessed load carrying capacity was compared with that of conventional steel reinforced columns of the same size. The yield load and ultimate load at failure withstood by the steel reinforced columns were considerably more than that of GFRP reinforced columns. The energy absorption capacity of GFRP reinforced columns was also poor compared to steel reinforced columns. Both the columns exhibited nearly the same ductile behaviour. Hence GFRP reinforcements are not recommendable for compression members.

Axial magnetic field injection in magnetized liner inertial fusion

NASA Astrophysics Data System (ADS)

Gourdain, P.-A.; Adams, M. B.; Davies, J. R.; Seyler, C. E.

2017-10-01

MagLIF is a fusion concept using a Z-pinch implosion to reach thermonuclear fusion. In current experiments, the implosion is driven by the Z-machine using 19 MA of electrical current with a rise time of 100 ns. MagLIF requires an initial axial magnetic field of 30 T to reduce heat losses to the liner wall during compression and to confine alpha particles during fusion burn. This field is generated well before the current ramp starts and needs to penetrate the transmission lines of the pulsed-power generator, as well as the liner itself. Consequently, the axial field rise time must exceed hundreds of microseconds. Any coil capable of being submitted to such a field for that length of time is inevitably bulky. The space required to fit the coil near the liner, increases the inductance of the load. In turn, the total current delivered to the load decreases since the voltage is limited by driver design. Yet, the large amount of current provided by the Z-machine can be used to produce the required 30 T field by tilting the return current posts surrounding the liner, eliminating the need for a separate coil. However, the problem now is the field penetration time, across the liner wall. This paper discusses why skin effect arguments do not hold in the presence of resistivity gradients. Numerical simulations show that fields larger than 30 T can diffuse across the liner wall in less than 60 ns, demonstrating that external coils can be replaced by return current posts with optimal helicity.

Feasibility study of determining axial stress in ferromagnetic bars using reciprocal amplitude of initial differential susceptibility obtained from static magnetization by permanent magnets

NASA Astrophysics Data System (ADS)

Deng, Dongge; Wu, Xinjun

2018-03-01

An electromagnetic method for determining axial stress in ferromagnetic bars is proposed. In this method, the tested bar is under the static magnetization provided by permanent magnets. The tested bar do not have to be magnetized up to the technical saturation because reciprocal amplitude of initial differential susceptibility (RAIDS) is adopted as the feature parameter. RAIDS is calculated from the radial magnetic flux density Br Lo = 0.5 at the Lift-off Lo = 0.5 mm, radial magnetic flux density Br Lo = 1 at the Lift-off Lo = 1 mm and axial magnetic flux density Bz Lo = 1 at the Lift-off Lo = 1 mm from the surface of the tested bar. Firstly, the theoretical derivation of RAIDS is carried out according to Gauss' law for magnetism, Ampere's Law and the Rayleigh relation in Rayleigh region. Secondly, the experimental system is set up for a 2-meter length and 20 mm diameter steel bar. Thirdly, an experiment is carried out on the steel bar to analyze the relationship between the obtained RAIDS and the axial stress. Experimental results show that the obtained RAIDS decreases almost linearly with the increment of the axial stress inside the steel bar in the initial elastic region. The proposed method has the potential to determine tensile axial stress in the slender cylindrical ferromagnetic bar.

Rotor whirl forces induced by the tip clearance effect in axial flow compressors

NASA Astrophysics Data System (ADS)

Ehrich, F.

1993-10-01

It is now widely recognized that destabilizing forces, tending to generate forward rotor whirl, are generated in axial flow turbines as a result of the nonuniform torque induced by the nonuniform tip-clearance in a deflected rotor-the so called Thomas/Alford force (Thomas, 1958, and Alford, 1965). It is also recognized that there will be a similar effect in axial flow compressors, but qualitative considerations cannot definitively establish the magnitude or even the direction of the induced whirling forces-that is, if they will tend to forward or backward whirl. Applying a 'parallel compressor' model to simulate the operation of a compressor rotor deflected radially in its clearance, it is possible to derive a quantitative estimate of the proportionality factor which relates the Thomas/Alford force in axial flow compressors (i.e., the tangential force generated by a radial deflection of the rotor) to the torque level in the compressor. The analysis makes use of experimental data from the GE Aircraft Engines Low Speed Research Compressor facility comparing the performance of three different axial flow compressors, each with four stages (typical of a mid-block of an aircraft gas turbine compressor) at two different clearances (expressed as a percent of blade length) - CL/L = 1.4 percent and CL/L = 2.8 percent. It is found that the value of Beta is in the range of + 0.27 to - 0.71 in the vicinity of the stages' nominal operating line and + 0.08 to - 1.25 in the vicinity of the stages' operation at peak efficiency. The value of Beta reaches a level of between - 1.16 and - 3.36 as the compressor is operated near its stalled condition. The final result bears a very strong resemblance to the correlation obtained by improvising a normalization of the experimental data of Vance and Laudadio (1984) and a generic relationship to the analytic results of Colding-Jorgensen (1990).

Effect of race, age, and axial length on optic nerve head parameters and retinal nerve fiber layer thickness measured by Cirrus HD-OCT.

PubMed

Knight, O'Rese J; Girkin, Christopher A; Budenz, Donald L; Durbin, Mary K; Feuer, William J

2012-03-01

To determine the effect of race, demographic, and ocular variables on optic nerve head and retinal nerve fiber layer (RNFL) thickness measurements using spectral-domain optical coherence tomography. In a cross-sectional observational study, 284 normal subjects aged 18 to 84 years were evaluated at 7 sites using Cirrus HD-OCT. Disc area, rim area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and average, temporal, superior, nasal, and inferior RNFL thicknesses were calculated. The main outcome measures were associations between Cirrus HD-OCT optic nerve head and RNFL measurements and age, sex, and race. The 284 subjects self-identified as being of European (122), Chinese (63), African (51), or Hispanic (35) descent. After adjusting for the effect of age, there was a statistically significant difference among racial groups for all optic nerve head and RNFL parameters (all P ≤ .005) except rim area (P = .22). Rim area, average cup-disc ratio, vertical cup-disc ratio, and cup volume were moderately associated with disc area (r(2) = 0.15, 0.33, 0.33, and 0.37, respectively). After a linear adjustment for disc area, there was no statistically significant difference among racial groups for any optic nerve head parameter. Individuals of European descent had thinner RNFL measurements except in the temporal quadrant. There are racial differences in optic disc area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and RNFL thickness as measured by Cirrus HD-OCT. These differences should be considered when using Cirrus HD-OCT to assess for glaucomatous damage in differing population groups.

Effect of Race, Age, and Axial Length on Optic Nerve Head Parameters and Retinal Nerve Fiber Layer Thickness Measured by Cirrus HD-OCT

PubMed Central

Knight, O’Rese J.; Girkin, Christopher A.; Budenz, Donald L.; Durbin, Mary K.; Feuer, William J.

2017-01-01

Objective To determine the effect of race, demographic, and ocular variables on optic nerve head and retinal nerve fiber layer (RNFL) thickness measurements using spectral-domain optical coherence tomography. Methods In a cross-sectional observational study, 284 normal subjects aged 18 to 84 years were evaluated at 7 sites using Cirrus HD-OCT. Disc area, rim area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and average, temporal, superior, nasal, and inferior RNFL thicknesses were calculated. The main outcome measures were associations between Cirrus HD-OCT optic nerve head and RNFL measurements and age, sex, and race. Results The 284 subjects self-identified as being of European (122), Chinese (63), African (51), or Hispanic (35) descent. After adjusting for the effect of age, there was a statistically significant difference among racial groups for all optic nerve head and RNFL parameters (all P≤.005) except rim area (P=.22). Rim area, average cup-disc ratio, vertical cup-disc ratio, and cup volume were moderately associated with disc area (r2=0.15, 0.33, 0.33, and 0.37, respectively). After a linear adjustment for disc area, there was no statistically significant difference among racial groups for any optic nerve head parameter. Individuals of European descent had thinner RNFL measurements except in the temporal quadrant. Conclusions There are racial differences in optic disc area, average cup-disc ratio, vertical cup-disc ratio, cup volume, and RNFL thickness as measured by Cirrus HD-OCT. These differences should be considered when using Cirrus HD-OCT to assess for glaucomatous damage in differing population groups. PMID:22411660

Social Relationships and Salivary Telomere Length Among Middle-Aged and Older African American and White Adults.

PubMed

Lincoln, Karen D; Lloyd, Donald A; Nguyen, Ann W

2017-05-09

A common mechanism underlying premature morbidity may be accelerated biological aging as reflected by salivary telomere length (STL). This study examined the extent to which social relationships, both positive and negative, can be protective or confer risk relative to biological aging. Data from the Health and Retirement Study and multiple regression were used to examine cross-sectional associations between STL, self-reported social support, and negative interaction (e.g., conflict, criticism) with family in a nationally representative sample of African American and non-Hispanic White middle-aged and older adults (N = 4,080). Social support from family was associated with shorter STL. Negative interaction with family had no main effect on STL but interactions characterized by high social support and more frequent negative interactions were associated with longer STL. Negative interaction with family was negatively associated with STL for African Americans and Whites but the magnitude of the effect was greater for African Americans. Study findings highlight the role of social relationships in physiological deterioration among middle-aged and older adults and identify a potential mechanism whereby race is linked to accelerated biological aging. Findings highlight the importance of considering positive and negative aspects of social relationships to understand the consequences of social connections for cellular aging in diverse populations. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

[Renal length measured by ultrasound in adult mexican population].

PubMed

Oyuela-Carrasco, J; Rodríguez-Castellanos, F; Kimura, E; Delgado-Hernández, R; Herrera-Félix, J P

2009-01-01

Renal length estimation by ultrasound is an important parameter in clinical evaluation of kidney disease and healthy donors. Changes in renal volume may be a sign of kidney disease. Correct interpretation of renal length requires the knowledge of normal limits, these have not been described for Latin American population. To describe normal renal length (RL) by ultrasonography in a group of Mexican adults. Ultrasound measure of RL in 153 healthy Mexican adults stratified by age. Describe the association of RL to several anthropometric variables. A total of 77 males and 76 females were scanner. The average age for the group was 44.12 +/- 15.44 years. The mean weight, body mass index (BMI) and height were 68.87 +/- 11.69 Kg, 26.77 +/- 3.82 kg/m2 and 160 +/- 8.62 cm respectively. Dividing the population by gender, showed a height of 166 +/- 6.15 cm for males and 154.7 +/- 5.97 cm for females (p =0.000). Left renal length (LRL) in the whole group was 105.8 +/- 7.56 mm and right renal length (RRL) was 104.3 +/- 6.45 mm (p = 0.000.) The LRL for males was 107.16 +/- 6.97 mm and for females was 104.6 +/- 7.96 mm. The average RRL for males was 105.74 +/- 5.74 mm and for females 102.99 +/- 6.85 mm (p = 0.008.) We noted that RL decreased with age and the rate of decline accelerates alter 60 years of age. Both lengths correlated significantly and positively with weight, BMI and height. The RL was significantly larger in males than in females in both kidneys (p = 0.036) in this Mexican population. Renal length declines after 60 years of age and specially after 70 years.

The Slotted Blade Axial-Flow Blower

DTIC Science & Technology

1955-09-01

YORK 18, NEW YORK w is|’ .THE SLOTTED BLADE AXIAL-FLOW BLOVER AUG 0 1 13941J F Dr. H. E. Sheets, Member ASME Chief Research and Development Engineer ... blades of an axial flow blower. The subject of boundary-layer control has attracted considerable attention in respect to the isolated airfoil (1)1 but... blades . Flow through airfoils displays a region of laminar flow beginning at the leading edge. Further downstream, at approximately the location of the

Functional-adaptive anatomy of the axial skeleton of some extant marsupials and the paleobiology of the paleocene marsupials Mayulestes ferox and Pucadelphys andinus.

PubMed

Argot, Christine

2003-03-01

In this study, the axial skeletons of two Early Paleocene marsupials, Mayulestes ferox and Pucadelphys andinus, were analyzed functionally and compared to that of six South American and three Australian species of extant marsupials. In the case of the South American opossums, myological data of the epaxial musculature were collected and analyzed and osteological-myological associations were related to locomotor behavior. Various features of the vertebral column that relate to diet or to locomotor or postural patterns were pointed out. These features include: the craniocaudal development of the neural process of the axis; the position of the anticlinal vertebra; the morphology of the neural processes of the thoracolumbar vertebrae (orientation, length, and craniocaudal width); the length, orientation, and curvature of the transverse processes of the lumbar vertebrae; and the length and robustness of the caudal vertebrae. In both fossil forms the vertebral column is mobile and allows a great range of flexion and extension of the spine, more so than in most of the living didelphids. It is emphasized here that the analysis of the axial skeleton complements and improves the conclusions provided by the forelimb and hindlimb analyses. It is proposed that Mayulestes and Pucadelphys represent an ancestral morphotype suggesting that the generalized type of locomotion of Paleocene marsupials was partly terrestrial with some climbing ability. Copyright 2003 Wiley-Liss, Inc.

Thermoelastic Damping in FGM Nano-Electromechanical System in Axial Vibration Based on Eringen Nonlocal Theory

NASA Astrophysics Data System (ADS)

Rahimi, Z.; Rashahmadi, S.

2017-11-01

The thermo-elastic damping is a dominant source of internal damping in micro-electromechanical systems (MEMS) and nano-electromechanical systems (NEMS). The internal damping cannot neither be controlled nor minimized unless either mechanical or geometrical properties are changed. Therefore, a novel FGMNEM system with a controllable thermo-elastic damping of axial vibration based on Eringen nonlocal theory is considered. The effects of different parameter like the gradient index, nonlocal parameter, length of nanobeam and ambient temperature on the thermo-elastic damping quality factor are presented. It is shown that the thermo-elastic damping can be controlled by changing different parameter.

Foot length--a new and potentially useful measurement in the neonate.

PubMed

James, D K; Dryburgh, E H; Chiswick, M L

1979-03-01

The foot length, occipito-frontal head circumference (OFC), crown-rump, and crown-heel length (CHL) of 123 neonates of gestational ages 26-42 weeks, were measured between 12 hours and 5 days. A gauge, designed and constructed at St Mary's Hospital, Manchester, was used to measure foot length. In term babies (37-42 weeks) who were of weights appropriate for gestational age (AGA) the scatter about the mean of foot length measurements was small (coefficient of variation = 4.5%) compared with birthweight (coefficient of variation = 12.0%). The wide range of foot length measurements in babies of different gestational ages prevented maturity being accurately estimated. The mean birthweight of term light-for-dates (LFD) babies was 30.9% lower than term AGA babies, whereas the mean foot length, OFC, and body length of LFD babies was reduced by only 4.2-8.8%. There was a positive linear correlation between foot length and other indices of body size in LFD and AGA babies of all gestational ages. However, in premature babies (less than 37 weeks) the correlation between foot length and birthweight (r = 0.95) and foot length and CHL (r = 0.96) was pronounced. The 95% confidence limits of the regression lines were +/- 327 g and +/- 2.3 cm respectively. Birthweight and CHL of premature babies can therefore be estimated from a measurement of foot length that is performed simply and rapidly. Measurements of foot length are valuable in premature babies who are too ill at birth for conventional anthropometric measurements to be made, and in whom such measurements cannot be carried out subsequently because of the encumbrance of the incubator and intensive care apparatus. Drug dosages and intravenous fluid requirements based on body weight or surface area can be indirectly calculated from a measurement of foot length.

Simultaneous refraction measurement and OCT axial biometry of the eye during accommodation (Conference Presentation)

NASA Astrophysics Data System (ADS)

De Freitas, Carolina; Hernandez, Victor M.; Ruggeri, Marco; Durkee, Heather A.; Williams, Siobhan; Gregori, Giovanni; Ho, Arthur; Manns, Fabrice; Parel, Jean-Marie

2016-03-01

The purpose of this project is to design and evaluate a system that will enable objective assessment of the optical accommodative response in real-time while acquiring axial biometric information. The system combines three sub-systems which were integrated and mounted on a joystick x-y-z adjustable modified slit-lamp base to facilitate alignment and data acquisition: (1) a Shack-Hartmann wavefront sensor for dynamic refraction measurement, provided software calculates sphere, cylinder and axis values, (2) an extended-depth Optical Coherence Tomography (OCT) system using an optical switch records high-resolution cross-sectional images across the length of the eye, from which, dynamic axial biometry (corneal thickness, anterior chamber depth, crystalline lens thickness and vitreous depth) can be extracted, and (3) a modified dual-channel accommodation stimulus unit based on the Badal optometer for providing a step change in accommodative stimulus. The prototypal system is capable of taking simultaneous measurements of both the optical and the mechanical response of lens accommodation. These measurements can provide insight into correlating changes in lens shape with changes in lens power and ocular refraction and ultimately provide a more comprehensive understanding of accommodation, presbyopia and an objective assessment of presbyopia correction techniques.

The axial crushes behaviour on foam-filled round Jute/Polyester composite tubes

NASA Astrophysics Data System (ADS)

Othman, A.; Ismail, A. E.

2018-04-01

The present paper investigates the effect of axial loading compression on jute fibre reinforced polyester composite round tubes. The specimen of composite tube was fabricated by hand lay-up method of 120 mm length with fix 50.8 mm inner diameter to determine the behaviour of energy absorption on number of layers of 450 angle fibre and internally reinforced with and without foam filler material. The foam filler material used in this studies were polyurethane (PU) and polystyrene (PE) with average of 40 and 45 kg/m3 densities on the axial crushing load against displacement relations and on the failure modes. The number of layers of on this study were two; three and four were selected to calculate the crush force efficiency (CFE) and the specific energy absorption (SEA) of the composite tubes. Result indicated that the four layers’ jute/polyester show significant value in term of crushing load compared to 2 and 3 layers higher 60% for 2 layer and 3% compared to 3 layers. It has been found that the specific energy absorption of the jute/polyester tubes with polystyrene foam-filled is found higher respectively 10% to 12% than empty and polyurethane (PU) foam tubes. The increase in the number of layers from two to four increases the mean axial load from 1.01 KN to 3.60 KN for empty jute/polyester and from 2.11 KN to 4.26 KN for the polyurethane (PU) foam-filled jute/polyester tubes as well as for 3.60 KN to 5.58 KN for the polystyrene (PE) foam-filled jute/polyester. The author’s found that the failure of mechanism influence the characteristic of curve load against displacement obtained and conclude that an increasing number of layers and introduce filler material enhance the capability of specific absorbed energy.

Longer leukocyte telomere length in Costa Rica's Nicoyan Peninsula: A population-based study

PubMed Central

Rehkopf, David H; Dow, William H; Rosero-Bixby, Luis; Lin, Jue; Epel, Elissa S; Blackburn, Elizabeth H

2013-01-01

Studies in humans suggest that leukocyte telomere length may act as a marker of biological aging. We investigated whether individuals in the Nicoya region of Costa Rica, known for exceptional longevity, had longer telomere length than those in other parts of the country. After controlling for age, age squared, rurality, rainy season and gender, mean leukocyte telomere length in Nicoya was substantially longer (81 base pairs, p<0.05) than in other areas of Costa Rica, providing evidence of a biological pathway to which this notable longevity may be related. This relationship remains unchanged (79 base pairs, p<0.05) after statistically controlling for nineteen potential biological, dietary and social and demographic mediators. Thus the difference in mean leukocyte telomere length that characterizes this unique region does not appear to be explainable by traditional behavioral and biological risk factors. More detailed examination of mean leukocyte telomere length by age shows that the regional telomere length difference declines at older ages. PMID:23988653

Elastic Buckling of Orthotropic Plates Under Varying Axial Stresses

NASA Technical Reports Server (NTRS)

Badir, Ashraf; Hu, Hurang; Diallo, Abdouramane

1997-01-01

The elastic buckling load of simply supported rectangular orthotropic plates subjected to a second degree parabolic variation of axial stresses in the longitudinal direction is calculated using analytical methods. The variation of axial stresses is equilibrated by nonuniform shear stresses along the plate edges and transverse normal stresses. The influence of the aspect ratio is examined, and the results are compared with plates subjected to uniform axial stresses.

Planned Axial Reorientation Investigation on Sloshsat

NASA Technical Reports Server (NTRS)

Chato, David J.

2000-01-01

This paper details the design and logic of an experimental investigation to study axial reorientation in low gravity. The Sloshsat free-flyer is described. The planned axial reorientation experiments and test matrixes are presented. Existing analytical tools are discussed. Estimates for settling range from 64 to 1127 seconds. The planned experiments are modelled using computational fluid dynamics. These models show promise in reducing settling estimates and demonstrate the ability of pulsed high thrust settling to emulate lower thrust continuous firing.

Molecular-Level Study of the Effect of Prior Axial Compression/Torsion on the Axial-Tensile Strength of PPTA Fibers

NASA Astrophysics Data System (ADS)

Grujicic, M.; Yavari, R.; Ramaswami, S.; Snipes, J. S.; Yen, C.-F.; Cheeseman, B. A.

2013-11-01

A comprehensive all-atom molecular-level computational investigation is carried out in order to identify and quantify: (i) the effect of prior longitudinal-compressive or axial-torsional loading on the longitudinal-tensile behavior of p-phenylene terephthalamide (PPTA) fibrils/fibers; and (ii) the role various microstructural/topological defects play in affecting this behavior. Experimental and computational results available in the relevant open literature were utilized to construct various defects within the molecular-level model and to assign the concentration to these defects consistent with the values generally encountered under "prototypical" PPTA-polymer synthesis and fiber fabrication conditions. When quantifying the effect of the prior longitudinal-compressive/axial-torsional loading on the longitudinal-tensile behavior of PPTA fibrils, the stochastic nature of the size/potency of these defects was taken into account. The results obtained revealed that: (a) due to the stochastic nature of the defect type, concentration/number density and size/potency, the PPTA fibril/fiber longitudinal-tensile strength is a statistical quantity possessing a characteristic probability density function; (b) application of the prior axial compression or axial torsion to the PPTA imperfect single-crystalline fibrils degrades their longitudinal-tensile strength and only slightly modifies the associated probability density function; and (c) introduction of the fibril/fiber interfaces into the computational analyses showed that prior axial torsion can induce major changes in the material microstructure, causing significant reductions in the PPTA-fiber longitudinal-tensile strength and appreciable changes in the associated probability density function.

Influence of the effective lens position, as predicted by axial length and keratometry, on the near add power of multifocal intraocular lenses.

PubMed

Savini, Giacomo; Hoffer, Kenneth J; Lombardo, Marco; Serrao, Sebastiano; Schiano-Lomoriello, Domenico; Ducoli, Pietro

2016-01-01

To calculate the near focal distance of different multifocal intraocular lenses (IOLs) as a function of the 2 parameters that are measured before cataract surgery; that is, axial length (AL) and refractive corneal power (keratometry [K]). GB Bietti Foundation IRCCS, Rome, Italy. Noninterventional theoretical study. The IOL power for emmetropia was first calculated in an eye model with the AL ranging from 20 to 30 mm and K from 38 to 48 diopters (D). Then, the predicted myopic refraction for any given IOL add power (from +1.5 to +4.0 D) was calculated, and from this value the near focal distance was obtained. Calculations were also performed for the average eye (K = 43.81 D; AL = 23.65 mm). The near focal distance increased with increasing values of K and AL for each near power add. The near focal distance ranged between 53 cm and 72 cm (21 inches and 28 inches) for a multifocal IOL with +2.50 D, between 44 cm and 60 cm (17 inches and 24 inches) for a multifocal IOL with +3.00 D add, and between 33 cm and 44 cm (13 inches and 18 inches) for a multifocal IOL with +4.00 D add. In the average eye, the near focal distance ranges between 36 cm (near add power = 4.00 D) and 99 cm (near add power = 1.5 D). Longer eyes with steeper corneas showed the longest near focal distance and could experience more difficulties in focusing near objects after surgery. The opposite was true for short hyperopic eyes. Dr. Hoffer receives licensing fees for the commercial use of the registered trademark Hoffer from all biometry manufacturers using the Hoffer Q formula to ensure that it is programmed correctly and book royalties from Slack, Inc., for the textbook IOL Power. None of the authors has a financial or proprietary interest in any material or method mentioned. Copyright © 2016 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Anomalous transport and generalized axial charge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirilin, Vladimir P.; Sadofyev, Andrey V.

For this article, we continue studying the modification of the axial charge in chiral media by macroscopic helicities. Recently it was shown that magnetic reconnections result in a persistent current of zero mode along flux tubes. Here we argue that in general a change in the helical part of the generalized axial charge results in the same phenomenon. Thus one may say that there is a novel realization of chiral effects requiring no initial chiral asymmetry. The transfer of flow helicity to zero modes is analyzed in a toy model based on a vortex reconnection in a chiral superfluid. Then,more » we discuss the balance between the two competing processes effect of reconnections and the chiral instability on the example of magnetic helicity. We argue that in the general case there is a possibility for the distribution of the axial charge between the magnetic and fermionic forms at the end of the instability.« less

Anomalous transport and generalized axial charge

DOE PAGES

Kirilin, Vladimir P.; Sadofyev, Andrey V.

2017-07-25

For this article, we continue studying the modification of the axial charge in chiral media by macroscopic helicities. Recently it was shown that magnetic reconnections result in a persistent current of zero mode along flux tubes. Here we argue that in general a change in the helical part of the generalized axial charge results in the same phenomenon. Thus one may say that there is a novel realization of chiral effects requiring no initial chiral asymmetry. The transfer of flow helicity to zero modes is analyzed in a toy model based on a vortex reconnection in a chiral superfluid. Then,more » we discuss the balance between the two competing processes effect of reconnections and the chiral instability on the example of magnetic helicity. We argue that in the general case there is a possibility for the distribution of the axial charge between the magnetic and fermionic forms at the end of the instability.« less

Axial diffusivity of the corona radiata correlated with ventricular size in adult hydrocephalus.

PubMed

Cauley, Keith A; Cataltepe, Oguz

2014-07-01

Hydrocephalus causes changes in the diffusion-tensor properties of periventricular white matter. Understanding the nature of these changes may aid in the diagnosis and treatment planning of this relatively common neurologic condition. Because ventricular size is a common measure of the severity of hydrocephalus, we hypothesized that a quantitative correlation could be made between the ventricular size and diffusion-tensor changes in the periventricular corona radiata. In this article, we investigated this relationship in adult patients with hydrocephalus and in healthy adult subjects. Diffusion-tensor imaging metrics of the corona radiata were correlated with ventricular size in 14 adult patients with acute hydrocephalus, 16 patients with long-standing hydrocephalus, and 48 consecutive healthy adult subjects. Regression analysis was performed to investigate the relationship between ventricular size and the diffusion-tensor metrics of the corona radiata. Subject age was analyzed as a covariable. There is a linear correlation between fractional anisotropy of the corona radiata and ventricular size in acute hydrocephalus (r = 0.784, p < 0.001), with positive correlation with axial diffusivity (r = 0.636, p = 0.014) and negative correlation with radial diffusivity (r = 0.668, p = 0.009). In healthy subjects, axial diffusion in the periventricular corona radiata is more strongly correlated with ventricular size than with patient age (r = 0.466, p < 0.001, compared with r = 0.058, p = 0.269). Axial diffusivity of the corona radiata is linearly correlated with ventricular size in healthy adults and in patients with hydrocephalus. Radial diffusivity of the corona radiata decreases linearly with ventricular size in acute hydrocephalus but is not significantly correlated with ventricular size in healthy subjects or in patients with long-standing hydrocephalus.

Magmatic controls on axial relief and faulting at mid-ocean ridges

NASA Astrophysics Data System (ADS)

Liu, Zhonglan; Buck, W. Roger

2018-06-01

Previous models do not simultaneously reproduce the observed range of axial relief and fault patterns at plate spreading centers. We suggest that this failure is due to the approximation that magmatic dikes open continuously rather than in discrete events. During short - lived events, dikes open not only in the strong axial lithosphere but also some distance into the underlying weaker asthenosphere. Axial valley relief affects the partitioning of magma between the lithosphere and asthenosphere during diking events. The deeper the valley, the more magma goes into lithospheric dikes in each event and so the greater the average opening rate of those dikes. The long-term rate of lithospheric dike opening controls faulting rate and axial depth. The feedback between axial valley depth D and lithospheric dike opening rate allows us to analytically relate steady-state values of D to lithospheric thickness HL and crustal thickness HC. A two-dimensional model numerical model with a fixed axial lithospheric structure illustrates the analytic model implications for axial faulting. The predictions of this new model are broadly consistent with global and segment-scale trends of axial depth and fault patterns with HL and HC.

Novel axially disubstituted non-aggregated silicon phthalocyanines.

PubMed

Bıyıklıoğlu, Zekeriya; Cakır, Dilek

2012-12-01

This paper describes the synthesis, spectroscopic characterization of a range of new axially-disubstituted silicon phthalocyanines with 2-[2-(dimethylamino)ethoxy] or 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy] groups as axial ligands. 2-[2-(Dimethylamino)ethoxy]ethanol 2, 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy]ethanol 4 are reacted with silicon phthalocyanine 1, to give an axially-disubstituted silicon phthalocyanines 3 and 5. Axially-disubstituted silicon phthalocyanine complexes were synthesized at the first time. Newly synthesized silicon phthalocyanines were characterized by UV-Vis, IR, (1)H NMR, (13)C NMR spectroscopy, ESI mass spectrometry. These new silicon(IV) phthalocyanines 3 and 5 showed excellent solubility in organic solvents such as CHCl(3), CH(2)Cl(2), acetone, DMF, DMSO, THF, EtOAc. The aggregation behavior of these compounds were investigated in different concentrations of DMSO. The effect of solvents on absorption spectra were studied in various organic solvents. The thermal stabilities of the silicon(IV) phthalocyanines 3 and 5 were determined by thermogravimetric analysis. Copyright © 2012 Elsevier B.V. All rights reserved.

Persistent Axial Dipole Decay for Past 400 Years Deduced from Lava Flows in Japan

NASA Astrophysics Data System (ADS)

Fukuma, K.

2017-12-01

Temporal variation of the axial dipole moment g10 was deduced from paleointensity data that were obtained from volcanic islands Izu-Oshima and Miyakejima in Japan for the last 400 years, combined with historical field model gufm1. The basaltic lava flows are precisely dated based on ancient documents on the eruptions. Essentially no age error is necessary to be counted. Thellier paleointensity measurements were performed using a fully automated magnetometer-furnace system "tspin" using about 450 specimens, which were mainly collected from clinkers and scorias. Appropriate Thellier temperature steps for each specimen were chosen, based on the thermomagnetic curve that was quite variable depending on the vertical position within a lava flow. The newly obtained paleointensities are much more consistent between sites and provide more reliable paleointensity variation than previous data from lava interiors. I applied the method as Gubbins et al. [2006] to this single spot paleointensity variation from Japan, and obtained persisitent decay of the axial dipole moment over the last 400 years. Contrary to gufm1's assumption that g10 linearly decayed from 1590 to 1840 as extrapolating the post-1840 instrumental records, Gubbins et al. [2006] argued no definite temporal trend on g10 recognizable from the existing archeointensity database. The g10 variation calculated from the previous paleointensity data are seriously discredited by both age and intensity errors resulted from various materials, locations and experimental methods involved. Our single spot and well-dated paleointensity data are free from the problems and support persistent axial dipole decay for past 400 years as assumed in gufm1.

Moderate and intense exercise lifestyles attenuate the effects of aging on telomere length and the survival and composition of T cell subpopulations.

PubMed

Silva, Léia Cristina Rodrigues; de Araújo, Adriana Ladeira; Fernandes, Juliana Ruiz; Matias, Manuella de Sousa Toledo; Silva, Paulo Roberto; Duarte, Alberto J S; Garcez Leme, Luiz Eugênio; Benard, Gil

2016-02-01

Studies indicate that exercise might delay human biological aging, but the effects of long-term exercise on T cell function are not well known. We tested the hypothesis that moderate or intense exercise lifestyle may attenuate the effects of aging on the telomere length and the survival and composition of T cell subpopulations. Elderly (65-85 years) with intense training lifestyle (IT, n = 15), moderate training lifestyle (MT, n = 16), and who never trained (NT, n = 15) were studied. Although the three groups presented the age-associated contraction of the TCD4(+)/TCD8(+) naïve compartments and expansion of the memory compartments, both training modalities were associated with lower proportion of terminally differentiated (CD45RA(+)CCR7(neg)) TCD4(+) and TCD8(+) cells, although among the latter cells, the reduction reached statistical significance only with IT. MT was associated with higher proportion of central memory TCD4(+) cells, while IT was associated with higher proportion of effector memory TCD8(+) cells. However, both training lifestyles were unable to modify the proportion of senescent (CD28(neg)) TCD8(+) cells. Telomeres were longer in T cells in both training groups; with IT, telomere length increased mainly in TCD8(+) cells, whereas with MT, a modest increase in telomere length was observed in both TCD8(+) and TCD4(+) cells. Reduced commitment to apoptosis of resting T cells, as assessed by caspase-3 and Bcl-2 expression, was seen predominantly with IT. Measurement of pro-inflammatory cytokines in serum and peripheral blood mononuclear cell (PBMC)'s supernatants did not show chronic low-grade inflammation in any of the groups. In conclusion, MT and IT lifestyles attenuated some of the effects of aging on the immune system.

Experimental investigation on circumferential and axial temperature gradient over fuel channel under LOCA

NASA Astrophysics Data System (ADS)

Yadav, Ashwini Kumar; kumar, Ravi; Gupta, Akhilesh; Chatterjee, Barun; Mukhopadhyay, Deb; Lele, H. G.

2014-06-01

In a nuclear reactor temperature rises drastically in fuel channels under loss of coolant accident due to failure of primary heat transportation system. Present investigation has been carried out to capture circumferential and axial temperature gradients during fully and partially voiding conditions in a fuel channel using 19 pin fuel element simulator. A series of experiments were carried out by supplying power to outer, middle and center rods of 19 pin fuel simulator in ratio of 1.4:1.1:1. The temperature at upper periphery of pressure tube (PT) was slightly higher than at bottom due to increase in local equivalent thermal conductivity from top to bottom of PT. To simulate fully voided conditions PT was pressurized at 2.0 MPa pressure with 17.5 kW power injection. Ballooning initiated from center and then propagates towards the ends and hence axial temperature difference has been observed along the length of PT. For asymmetric heating, upper eight rods of fuel simulator were activated and temperature difference up-to 250 °C has been observed from top to bottom periphery of PT. Such situation creates steep circumferential temperature gradient over PT and could lead to breaching of PT under high pressure.

Three-dimensional Aerodynamic Instability in Multi-stage Axial Compressors

NASA Technical Reports Server (NTRS)

Suder, Kenneth (Technical Monitor); Tan, Choon-Sooi

2003-01-01

Four separate tasks are reported. The first task: A Computational Model for Short Wavelength Stall Inception and Development In Multi-Stage Compressors; the second task: Three-dimensional Rotating Stall Inception and Effects of Rotating Tip Clearance Asymmetry in Axial Compressors; the third task:Development of an Effective Computational Methodology for Body Force Representation of High-speed Rotor 37; and the fourth task:Development of Circumferential Inlet Distortion through a Representative Eleven Stage High-speed axial compressor. The common theme that threaded throughout these four tasks is the conceptual framework that consists of quantifying flow processes at the fadcompressor blade passage level to define the compressor performance characteristics needed for addressing physical phenomena such compressor aerodynamic instability and compressor response to flow distoriton with length scales larger than compressor blade-to-blade spacing at the system level. The results from these two levels can be synthesized to: (1) simulate compressor aerodynamic instability inception local to a blade rotor tip and its development from a local flow event into the nonlinear limit cycle instability that involves the entire compressor as was demonstrated in the first task; (2) determine the conditions under which compressor stability assessment based on two-dimensional model may not be adequate and the effects of self-induced flow distortion on compressor stability limit as in the second task; (3) quantify multistage compressor response to inlet distortion in stagnation pressure as illustrated in the fourth task; and (4) elucidate its potential applicability for compressor map generation under uniform as well as non-uniform inlet flow given three-dimensional Navier-Stokes solution for each individual blade row as was demonstrated in the third task.

Organocatalytic atroposelective synthesis of axially chiral styrenes

NASA Astrophysics Data System (ADS)

Zheng, Sheng-Cai; Wu, San; Zhou, Qinghai; Chung, Lung Wa; Ye, Liu; Tan, Bin

2017-05-01

Axially chiral compounds are widespread in biologically active compounds and are useful chiral ligands or organocatalysts in asymmetric catalysis. It is well-known that styrenes are one of the most abundant and principal feedstocks and thus represent excellent prospective building blocks for chemical synthesis. Driven by the development of atroposelective synthesis of axially chiral styrene derivatives, we discovered herein the asymmetric organocatalytic approach via direct Michael addition reaction of substituted diones/ketone esters/malononitrile to alkynals. The axially chiral styrene compounds were produced with good chemical yields, enantioselectivities and almost complete E/Z-selectivities through a secondary amine-catalysed iminium activation strategy under mild conditions. Such structural motifs are important precursors for further transformations into biologically active compounds and synthetic useful intermediates and may have potential applications in asymmetric synthesis as olefin ligands or organocatalysts.

Postnatal change in sulcal length asymmetry in cerebrum of cynomolgus monkeys (Macaca fascicularis).

PubMed

Sakamoto, Kazuhito; Sawada, Kazuhiko; Fukunishi, Katsuhiro; Noritaka, Imai; Sakata-Haga, Hiromi; Yoshihiro, Fukui

2014-02-01

The purpose of this study was to determine the timing of the onset of adult-type sulcal length asymmetry during postnatal development of the male cynomolgus monkey cerebrum. The monkey brain has already reached adult size by 3 months of age, although the body weight only represents 1/8 of the adult body weight by that time. The fronto-occipital length and the cerebral width also reached adult levels by that postnatal age with no left/right bias. Consistently, lengths of the major primary sulci reached adult levels by 3 months of age, and then decreased slightly in sexually mature monkeys (4-6.5 years of age). Asymmetry quotient analysis showed that sulcal length asymmetry patterns gradually changed during postnatal development. The male adult pattern of sulcal length asymmetry was acquired after 24 months of age. In particular, age-dependent rightward lateralization of the arcuate sulcal length was revealed during cerebral maturation by three-way ANOVA. The results suggest that the regional difference in cerebral maturation from adolescence to young adulthood modifies the sulcal morphology with characteristic asymmetric patterns in male cynomolgus monkeys. Copyright © 2013 Wiley Periodicals, Inc.

Crystalline lens paradoxes revisited: significance of age-related restructuring of the GRIN.

PubMed

Sheil, Conor J; Goncharov, Alexander V

2017-09-01

The accommodating volume-constant age-dependent optical (AVOCADO) model of the crystalline lens is used to explore the age-related changes in ocular power and spherical aberration. The additional parameter m in the GRIN lens model allows decoupling of the axial and radial GRIN profiles, and is used to stabilise the age-related change in ocular power. Data for age-related changes in ocular geometry and lens parameter P in the axial GRIN profile were taken from published experimental data. In our age-dependent eye model, the ocular refractive power shows behaviour similar to the previously unexplained "lens paradox". Furthermore, ocular spherical aberration agrees with the data average, in contrast to the proposed "spherical aberration paradox". The additional flexibility afforded by parameter m , which controls the ratio of the axial and radial GRIN profile exponents, has allowed us to study the restructuring of the lens GRIN medium with age, resulting in a new interpretation of the origin of the power and spherical aberration paradoxes. Our findings also contradict the conceptual idea that the ageing eye is similar to the accommodating eye.

Frequency response of a thermocouple wire: Effects of axial conduction

NASA Technical Reports Server (NTRS)

Forney, L. J.; Fralick, G. C.

1990-01-01

Theoretical expressions are derived for the steady-state frequency response of a thermocouple wire. In particular, the effects of axial heat conduction are demonstrated for both a uniform thermocouple wire and a nonuniform wire with unequal material properties and wire diameters across the junction. For the case of a uniform wire, the amplitude ratio and phase angle compare favorably with the series solution of Scadron and Warshawsky (1952) except near the ends of the wire. For the case of a non-uniform wire, the amplitude ratio at low frequency omega yields 0 agrees with the results of Scadron and Warshawsky for a steady-state temperature distribution. Moreover, the frequency response for a non-uniform wire in the limit of infinite length l yields infinity is shown to reduce to a simple expression that is analogous to the classic first order solution for a thermocouple wire with uniform properties.

Continuous millennial decrease of the Earth's magnetic axial dipole

NASA Astrophysics Data System (ADS)

Poletti, Wilbor; Biggin, Andrew J.; Trindade, Ricardo I. F.; Hartmann, Gelvam A.; Terra-Nova, Filipe

2018-01-01

Since the establishment of direct estimations of the Earth's magnetic field intensity in the first half of the nineteenth century, a continuous decay of the axial dipole component has been observed and variously speculated to be linked to an imminent reversal of the geomagnetic field. Furthermore, indirect estimations from anthropologically made materials and volcanic derivatives suggest that this decrease began significantly earlier than direct measurements have been available. Here, we carefully reassess the available archaeointensity dataset for the last two millennia, and show a good correspondence between direct (observatory/satellite) and indirect (archaeomagnetic) estimates of the axial dipole moment creating, in effect, a proxy to expand our analysis back in time. Our results suggest a continuous linear decay as the most parsimonious long-term description of the axial dipole variation for the last millennium. We thus suggest that a break in the symmetry of axial dipole moment advective sources occurred approximately 1100 years earlier than previously described. In addition, based on the observed dipole secular variation timescale, we speculate that the weakening of the axial dipole may end soon.

Theoretical Determination of Axial Fan Performance

NASA Technical Reports Server (NTRS)

Struve, E.

1943-01-01

The report presents a method for the computation of axial fan characteristics. The method is based on the assumption that the law of constancy of the circulation along the blade holds, approximately, for all fan conditions for which the blade elements operate at normal angles of attack (up to the stalling angles). Pressure head coefficient K(sub a) and power coefficient K(sub u) for the force components in the axial and tangential directions, respectively, and analogous to the lift and drag coefficients C(sub y) and C(sub x) are conveniently introduced.

Guidelines for magnetic resonance imaging in axial spondyloarthritis: A Delphi study.

PubMed

Narváez, J A; Bueno Horcajadas, A; de Miguel Mendieta, E; Sanz Sanz, J

2015-01-01

The term axial spondyloarthritis refers to a group of chronic inflammatory rheumatic diseases with a common genetic basis that course with axial and peripheral involvement and enthesitis. Recently, the Assessment of SpondyloArthritis international Society (ASAS) established some diagnostic criteria, including for the first time magnetic resonance imaging (MRI) findings. Given the difficulties of obtaining MRI in some environments and the lack of experience with axial spondyloarthritis, a group of radiologists and rheumatologists sought to establish some practical guidelines to ensure the correct use of MRI in this disease. Using the Delphi method, we used a questionnaire with 49 items stratified into 4 blocks to survey 46 experts in the MRI diagnosis of axial spondyloarthritis. The experts agreed on 82% of the items. The degree of agreement was 100% in the block "Importance of early diagnosis of axial spondyloarthritis", 69% in the block "Optimization of the use of MRI in the diagnosis of axial spondyloarthritis", 93% in the block "Use of MRI in axial spondyloarthritis: Technical aspects", and 57% in the block "Usefulness of MRI in the prognosis, follow-up, and evaluation of the response to treatment in axial spondyloarthritis". Despite the importance of MRI in the early diagnosis of axial spondyloarthritis, this study shows the need for standardization and points to relative disagreement about how to use MRI in the follow-up of the disease and evaluation of the response to treatment. The results of this study can help improve the use of MRI in axial spondyloarthritis. Copyright © 2014 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Altered Axial Skeletal Development

EPA Science Inventory