Assessment Of Aging Effects Research Articles

Assessment of Age Effects on Ovarian Hemodynamics Using Doppler Ultrasound and Progesterone Concentrations in Cycling Spanish Purebred Mares.

Simple SummaryPower Doppler is a non-invasive imaging technique that allows complete monitoring of the ovary changes in cycling mares. We use Power Doppler to investigate differences in follicular diameter and corpus luteum area as well as in follicular and corpus luteum blood flows between young and mature Spanish Purebred mares. Young mares had higher follicular and corpus luteum blood flows as well as higher blood progesterone levels. Moreover, we found that blood progesterone levels could be predicted in both groups from corpus luteum blood flow with moderate precision and accuracy. These results support the usefulness of Power Doppler to monitor ovarian hemodynamics and the suitability of corpus luteum blood flow to estimate blood progesterone levels in cycling mares.In equine reproduction, accurate and timely detection of the moment of ovulation is of great importance. Power Doppler ultrasound technology is a non-invasive method that enables to assess the morpho-echogenic features and blood flow changes during the estral cycle in mares. The objective of the present study was to evaluate the influence of age on ultrasonographic parameters (follicular diameter, follicular blood flow—FBF, corpus luteum (CL) area and corpus luteum blood flow—CLBF) and blood plasma progesterone concentrations in cycling Spanish Purebred mares (15 less than 8 years old and 15 equal o higher than 8 years old). The ultrasound images obtained were analyzed with the Image Colour Summarizer software, which allows the quantification of the pixels of each image. Young mares had significantly higher FBF, CLBF and plasma progesterone levels. Moreover, linear regression analysis showed that blood progesterone levels could be predicted in both groups from CLBF with moderate precision and accuracy. In conclusion, Power Doppler was useful to assess ovarian hemodynamics. Our results support that age is a factor that significantly influences FBF and CLBF as well as blood progesterone concentration in mares. More studies would be needed to develop high precision and accuracy predictive models of blood progesterone concentration from CLBF measured by Power Doppler.

State of the art in the assessment of aging effects on soil liquefaction

A review of the current state of the art in the assessment of aging effects on soil liquefaction is presented in this paper. The review includes a summary of several field case histories indicating greater resistance to liquefaction in aged soils than in young uncemented soils during earthquakes, a discussion of the mechanisms that increase liquefaction resistance with time, an evaluation of proposed methods for quantifying the influence of aging processes (or diagenesis) on liquefaction resistance (KDR), and an evaluation of proposed predictor variables for KDR. The published literature indicates physical diagenetic processes tend to dominate the nature of interactions at the grain-to-grain contacts of sand deposits in the absence of sufficient cementing agents, while chemical processes tend to dominate where sufficient cementing agents are present. Variables proposed for predicting KDR include: the time since deposition or last critical disturbance; the ratio of measured to estimated small-strain shear wave velocity (MEVR); the ratio of small-strain shear modulus to cone tip resistance (Gmax/qc); the adjusted Gmax/qc (KG); and the ratio of measured to estimated adjusted Gmax/qc (MEKG). It is shown that MEVR, Gmax/qc, KG and MEKG are all ratios of measured to estimated or reference shear wave velocity. MEVR and Gmax/qc are slightly more robust predictors (i.e., regression equations with higher coefficient of regression and lower root mean square error) of KDR than KG and MEKG. Time is the least robust predictor of KDR.

Comparative performance analysis of grid-connected photovoltaic system by use of existing performance models

Performance analysis of real world efficiency of photovoltaic installations is proven to be a challenging task, as demonstrated by the processing of data from monitoring operation of a photovoltaic park for a period of 3years. It is important to establish a procedure which evaluates the photovoltaic plant performance based on real world system monitoring data. The role of air mass and clearness index variations in this context is well established and the analysis is conducted with the aid of these factors. The analysis has three main objectives: (i) the evaluation of three existing models, (ii) performance ratio calculation and (iii) the formulation of an evaluation procedure based on normalization to Standard Reporting Conditions. Processing of the monitoring data reveals significant scatter in normalized efficiency. A 10% fluctuation in yearly energy production is observed in the period 2013–2015. It is important to analyze this fluctuation in order to shed light to the reasons behind this fact. Performance ratio analysis, normalization procedure and models comparison, point to a decrease in PV panel’s efficiency from the first year of operation. However, this is a small decrease covered by the terms of the manufacturer’s warranty. Application of the proposed procedure to the analysis of data from older installations is expected to improve understanding and assessment of aging effects in the PV panels.

A gaussian mixture model approach for estimating and comparing the shapes of distributions of neuroimaging data: diffusion-measured aging effects in brain white matter.

Neuroimaging signal intensity measures underlying physiology at each voxel unit. The brain-wide distribution of signal intensities may be used to assess gross brain abnormality. To compare distributions of brain image data between groups, t-tests are widely applied. This approach, however, only compares group means and fails to consider the shapes of the distributions. We propose a simple approach for estimating both subject- and group-level density functions based on the framework of Gaussian mixture modeling, with mixture probabilities that are testable between groups. We demonstrate this approach by application to the analysis of fractional anisotropy image data for assessment of aging effects in white matter.

CURRENT STATUS AND PROSPECT FOR PERIODIC SAFETY REVIEW OF AGING NUCLEAR POWER PLANTS IN KOREA

Korean utility has utilized a Periodic Safety Review (PSR) that assesses the cumulative effects of plant aging, modifications, operating experience, technical developments, and site characteristics since 2000. In particular, the assessment and management of plant aging is one of the major areas in PSR. It includes identification of critical Systems, Structures, and Components (SSCs) for aging, assessment of aging effects, and implementation of aging management programs. Since the PSR system was introduced based on the atomic energy acts and related laws, PSRs of eight sets for 12 Nuclear Power Plants (NPPs) that have been operating more than 10 years have been completed. PSRs of two sets for 4 NPPs are currently being carried out. The utility has confirmed that domestic NPPs have been operated safely through these PSRs and have implemented the follow-up corrective activities to increase the nuclear safety. In this paper, the status of PSR implementation is discussed and improvement programs to conduct PSR follow-up corrective activities efficiently for NPPs are suggested based on experiences with aging assessments.

Episodic and semantic remote autobiographical memory in ageing

Many laboratory studies have demonstrated an age effect on episodic memory which is in contrast with the preservation of semantic memory. The aim of this study was the assessment of age effects on autobiographical memory according to the length of the retention interval, taking into account the episodic and semantic components. A total of 52 subjects, aged between 40 and 79, were divided into four age groups. They were tested with a sophisticated autobiographical questionnaire consisting of two tasks, one involving the recall of semantic information and another the recall of episodic events. Results revealed that episodic recall deteriorated more with age and retention interval than semantic recall. These data, gathered using an ecological test, confirm age differences demonstrated by laboratory tests on the episodic-semantic distinction. Furthermore, the profile of results obtained for the recall of specific detailed events, and analysed according to age of encoding, confirms the distribution of episodic memories across the lifespan, as modelled by Rubin, Wetzler, and Nebes (1986) with the cue-word technique.

Aging effects upon pursuit eye movements.

Quantitative assessment of aging effects upon pursuit eye movements was done in step-ramp stimulus conditions using 32 normal individuals. Eye movements were recorded with infrared reflection oculography. The target was a spot of 0.5 degree red lazar light. The light spot was blanked for 5 ms while the mirror galvanometer moved to a new position. Eye and target position were sampled at 250 Hz and analysed by a personal computer. In onward stimulation in which 2 degrees, 4 degrees, 6 degrees and 8 degrees position steps were followed by fixed ramp speed (10 degrees/s), and also in backward stimulation in which 2 degrees, 4 degrees, 6 degrees step positions were followed by 9 degrees, 17 degrees and 27 degrees/s, eye acceleration increased depending upon increase of retinal slip velocity in the younger group below 49 years. Among the factors effecting aging effects, the cerebrum might be important because visual recognition and eye acceleration are performed in the parietal lobe.