Narrow Results

The biomechanical properties of arteries play a crucial role in governing the overall hemodynamic function of the circulatory system. The nonuniformity in elastic and geometric structures of the blood vessels adds on to the complexity in dealing with pulsatile natures of blood pressure and flow. Short-term or chronic changes in arterial wall properties subjecting to distending pressure and perfusing flow make quantification of arterial compliance especially important in its use in describing the overall arterial function. This paper will first review the methodologies of determining arterial compliance in systole, in diastole and varying throughout the entire cardiac cycle. The stroke volume-to-pulse pressure method, the linear Windkessel model-based approaches and the nonlinear pressure-dependent compliance model method to derive arterial compliance are presented. The clinical relevance and implications are highlighted accordingly, in particular, the consequences of hypertension and aging.

Developing Asia has grown faster than other parts of the world for decades. However, population aging is expected to pose significant headwinds to the region’s future economic growth. We update and enhance the analysis of Park and Shin (2012) to project the impact of population aging on developing Asia’s growth between 2021 and 2050. Our projections indicate that a demographic transition will have a substantial negative effect on the region’s future growth, but the effect varies across economies. Older economies will suffer a demographic tax, whereas younger economies will continue to enjoy a positive but declining demographic dividend.

Purpose: This study investigated the effects of grinding, polishing and aging on physical properties using self-made zirconia and commonly used ultraclear ceramic materials and glass ceramics in the clinic. Methods: The samples were prepared using 3% yttria-stabilized zirconia ceramic (3Y-TZP) powder containing alumina, which was granulated by ball milling. Then, it is pressed into a circular sheet together with Upcera and Wieland materials. The glass ceramic materials are molded. Finally, all materials were subjected to hydrothermal aging. Results: The self-made zirconia had better permeability than the commonly used ultratransparent ceramic materials and glass ceramics. The polishing after grinding improved the surface morphology and roughness of tooth transparent ceramic materials; Polishing after grinding improved the aging resistance of zirconia materials. The bending strength of self-made samples was less than that of two kinds of ceramics commonly used in clinic, but greater than that of glass ceramics. Aging improved the bending strength of zirconia. Conclusions: The self-made zirconia had better permeability than ultratransparent all-ceramic materials and glass ceramics, and its bending strength was better than that of glass ceramics. Grinding and polishing could improve not only the surface morphology and roughness but also the strength and aging resistance.

Since the 1970s, due to the combination of the declining birthrate and rising longevity, the speed of population aging in Japan has been more dramatic than in any other developed country. Consequently, the growth of the working population, which had been faster than the growth of the total population, has gradually become slower in recent years than the latter in Japan. Moreover, similar rapid demographic changes are taking place at various speeds in all prefectures. By introducing demographic variables into empirical models of regional economic growth, which is based on prefecture-level panel data for the period 1980–2010, this paper shows that the recent demographic changes in Japan have had significant effects on its regional economic growth: the contribution of the growth rate difference between the working population and the total population to per capita Gross Regional Domestic Product (GRDP) growth rate, i.e., the demographic bonus, has disappeared. In addition, the growth rate of the aged population (65 years old and over) has had a very significant negative effect on per capita GRDP growth rate, while the growth rate of the young population aged 0–14 has had a significant positive effect. The findings of this study imply that Japan’s population aging and other ongoing demographic changes will continue to depress economic growth in all prefectures. Given the low probability of a significant rise in the birth rate and the rapid increase in the local labor supply, it is important for all prefectures in Japan to raise the quality of their labor-force and improve productivity. Meanwhile, effectively attracting young skilled workers to migrate from other regions/countries should be a key policy issue for both local and central governments in Japan.

The People’s Republic of China is aging rapidly at one of the most rapid paces in the world. The resulting decline in the share of the population that is of working age creates challenges for both the economy and society, making it relevant to explore the health capacity to work among older persons. Using census data and data from the China Health and Retirement Longitudinal Study, this paper applies two widely used methods to estimate the additional health capacity to work. The results confirm large untapped work capacity in the population of older persons, but the additional health capacity to work is unevenly distributed among different groups: Women and urban residents have more additional work capacity than men and older persons in rural areas. Pension systems and variation in types of work contribute to the urban–rural difference.

This paper uses two methodologies to explore the extent to which greater labor force participation among older Malaysians can expand Malaysia’s labor supply. The Milligan–Wise method estimates the potential to increase the labor force participation rate of older Malaysians by estimating how much they would work if they were to work as much as those with the same mortality rate in the past. The Cutler, Meara, and Richards-Shubik (2013) method estimates the same potential by estimating how much older Malaysians would work if they worked as much as their younger counterparts in similar health. We made further simulations to quantify the capacity of older Malaysians to work after they are 60 years old. The results show significant additional work capacity among older people in Malaysia, particularly males, urban dwellers, and those with low educational attainment.

It is known that heart activity changes during aging. In this paper, we evaluated alterations of heart activity from the complexity point of view. We analyzed the variations of heart rate of patients with congestive heart failure that are categorized into four different age groups, namely 30–39, 50–59, 60–69, and 70–79 years old. For this purpose, we employed three complexity measures that include fractal dimension, sample entropy, and approximate entropy. The results showed that the trend of increment of subjects’ age is reflected in the trend of increment of the complexity of heart rate variability (HRV) since the values of fractal dimension, approximate entropy, and sample entropy increase as subjects get older. The analysis of the complexity of other physiological signals can be further considered to investigate the variations of activity of other organs due to aging.

One of the important areas of heart research is investigating how heart activity changes during aging. In this research, we employed complexity-based techniques to analyze how heart activity varies based on the age of subjects. For this purpose, the heart rate variability (HRV) of 54 healthy subjects (30 M, 24 F, 28.5–76 years old) in three different age groups was analyzed using fractal theory, sample entropy, and approximate entropy. We showed that the fractal dimension, sample entropy, and approximate entropy of the RR interval time series (as HRV) are related to the age of the subjects. In other words, as subjects get older, the complexity of their RR interval time series decreases. Therefore, we decoded the variations in HRV during aging. The method of analysis that was employed in this research can be used to analyze the variations of other physiological signals (e.g. Electroencephalogram (EEG) signals) during aging.

Aging can cause degenerative changes in multiple tissues and organs. Gastrointestinal diseases and dysfunctions are common in the elderly population. In this study, we investigated the effects of Astragalus membranaceus polysaccharide (APS) and Astragalus membranaceus ethanol extract (AEE) on age-related intestinal dysfunction and gut microbiota dysbiosis in naturally aging mice. The energy expenditure and physical activity of 23-month-old C57BL6/J mice were recorded using a metabolic cage system. Pathological changes in the intestine were evaluated using Alcian blue staining. The protein levels of leucine-rich repeats containing G protein-coupled receptor 5 (Lgr5) and Stat3 in the small intestine were determined using immunohistochemistry. The intestinal cell migration distance was assessed using bromodeoxyuridine (BrdU) immunofluorescence staining. The gene transcription levels of intestinal stem cell (ISC) markers and ISC-related signaling pathways were detected using quantitative real-time PCR (qRT-PCR). Microbiota analysis based on 16S rDNA was performed to evaluate the composition of the gut microbiota. APS and AEE improved a series of aging phenotypes in female but not in male aging mice. APS and AEE ameliorate intestinal dysfunction and histopathological changes in aging mice. APS had a more significant anti-aging effect than AEE, particularly on intestinal dysfunction. APS promotes ISC regeneration by activating the IL-22 signaling pathway. Cohousing (CH) experiments further confirmed that APS induced the IL-22 signaling pathway by increasing the abundance of Lactobacillus, thereby promoting the regeneration of ISCs. Our results show that APS may serve as a promising agent for improving age-related intestinal dysfunction.

With the acceleration of population aging in China, the number of pure beneficiaries in the economy is higher than that of pure contributors, which seriously affects fiscal sustainability. This paper probes into the influence path and mechanism of population aging to fiscal sustainability in China, and numerically simulates the extent of such influence using a generational accounting method. Aging reduces the tax base and enlarges fiscal expenditure by reducing the quantity of labor and labor productivity, changing the resident’s consumption level and structure, cutting down the saving rate, and widening the gap between social security revenue and expenditure, all of which challenge the balance of the fiscal system. The empirical results show that the problem of inequality in terms of the fiscal burden across generations is extremely prominent and the per capita tax burden under different birth rate assumptions is obviously different. Under the pressure of aging, in order to maintain the fiscal balance, the future per capita tax burden will be increased by a maximum of 55.9%. Although increasing productivity and reducing interest rates can help reduce that gap, their roles are far less important than the role of fertility. In order to cope with aging, the fiscal system should see an increase in income, a reduction in expenditure, and a redeployment of structure. That is, while at the same time perfecting the tax system and widening the tax base, the expenditure structure should also be optimized.

Ti–6Al–2Sn–4Zr–2Mo (Ti-6242), a near-$\alpha$ titanium alloy explicitly designed for high-temperature applications, consists of a martensitic structure after selective laser melting (SLM). However, martensite is thermally unstable and thus adverse to the long-term service at high temperatures. Hence, understanding martensite decomposition is a high priority for seeking post-heat treatment for SLMed Ti-6242. Besides, compared to the room-temperature titanium alloys like Ti–6Al–4V, aging treatment is indispensable to high-temperature near-$\alpha$ titanium alloys so that their microstructures and mechanical properties are pre-stabilized before working at elevated temperatures. Therefore, the aging response of the material is another concern of this study. To elaborate the two concerns, SLMed Ti-6242 was first isothermally annealed at 650${}^{\circ }\mathrm{\text{C}}\le T\le 1025^{\circ }$C and then water-quenched to room temperature, followed by standard aging at 595${}^{\circ }$C. The microstructure analysis revealed a temperature-dependent martensite decomposition, which proceeded sluggishly at $T\le 700^{\circ }$C despite a long duration but rapidly transformed into lamellar $\alpha +\beta$ above the martensite transition zone (770${}^{\circ }\mathrm{\text{C}}\le T\le 800^{\circ }$C). As heating to $T>\beta -\mathrm{\text{transus}}(993^{\circ }$C), it produced a coarse microstructure containing new martensites formed in water quenching. The subsequent mechanical testing indicated that SLM-built Ti-6242 is excellent in terms of both room- and high-temperature tensile properties, with around 1400 MPa (UTS)$+$5% elongation and 1150 MPa (UTS)$+$10% elongation, respectively. However, the combination of water quenching and aging embrittled the as-built material severely.

Proprioception while standing is important for the balance control, but the proprioception has not been investigated in the unconstrained standing conditions. The purpose of this study was to investigate the effects of age and gender on the thresholds of perception and muscle response in response to the support surface rotation. The experiment was designed so that the thresholds depend mainly on the proprioception, i.e., quasistatic condition (0.2^∘/s rotation of the platform) with eyes closed. Fifty-two healthy subjects (half young and half elderly) participated in this study. A platform was developed which can be rotated in four directions. Perception threshold angle was registered from subjects’ pressing a button. Muscle response threshold angle was determined as the earlier onset of EMG in lower limb muscles. Two standing conditions (feet together and natural stance) were tested. Repeated-measures ANOVA showed that both thresholds increased with age. Post hoc tests revealed (1) that the perception threshold was greater for women than men in the elderly and (2) both thresholds of the elderly were greater for the feet-together stance than natural stance. Inferior perception sensitivity of platform rotation in elderly women may be associated with inferior performance in cortical postural control and greater fall ratio compared to elderly men, which suggests the need of proprioception trainings.

Is Japan’s aging and, more recently, declining population hampering its growth and reflation efforts? Exploiting the demographic and economic variation in the prefectural data between 1990 and 2007, we find that aging of the working age population has had a significant negative impact on the total factor productivity (TFP). Moreover, prefectures that aged at a faster pace experienced lower overall inflation, while prefectures with higher population growth experienced higher inflation. The results give strong support to the notion that demographic headwinds can have a non-trivial impact on the TFP and deflationary pressures.

Ability of epitaxial perovskite oxide ferroelectric films to maintain a poled polarization state on a long-term scale is crucial for advanced devices employing such films. Here polarization relaxation with time, or aging, is experimentally studied in epitaxial capacitor heterostructures of PbTiO₃ sandwiched between SrRuO₃ and Pt electrodes. The relaxation obeys logarithmic time-decay for the time 10²–10⁵s after poling pulses. The decay is by factor $\sim$10 slower than that reported for polycrystalline films. Our experimental results show that existing models are insufficient for epitaxial films.

Britton Chance pursued his research and sailing until his death at age 97. His 100th anniversary was memorialized in this paper from longevity viewpoint. His lifelong work was very creative. His life was very colorful. His aging was very successful. He has lived a longevity.

This paper estimates the impact of population aging on bilateral pork trade between 32 Asian countries (regions) by using a gravity model that incorporates old-age dependency ratio variables. The Poisson pseudo-maximum-likelihood regression performs better than the ordinary least-squares method in the estimations. An aging labor force stimulates pork exports because it reduces pork production costs by supplying the pork industry with low-wage older laborers. An aging consumer-based economy increases pork imports because older consumers usually have higher incomes. Population aging has both a time characteristic and a country characteristic on pork trade in Asia. Increasing birth rates and reforming the pork industry from the supply side are two feasible policy recommendations for aging Asian countries (regions).

The consensus of the normal magnitude of lumbosacral curve has not been achieved. The Cobb's angle cannot depict the whole contour of this curve. For practical applications, a clearer image of these curves and their aging changes should be further investigated. This study aimed to provide a more consolidate concept of normal lumbosacral curves for clinician through a computerized reconstruction method.

Standing lateral radiographs of lumbosacral spine in 82 normal adults were used for reconstructing the sagittal lumbosacral curves. The geometric characteristics of these curves according to the gender and age groups were studied. Using standing lateral radiographs, reconstruction of the lumbosacral curves was performed through digitization, programming and computation. These curves and related parameters were normalized and averaged for analyzing the differences of gender and age.

The most anteriorward and horizontal vertebrae usually occurred on the L4 and L3 in any gender and age groups. The sacral inclination angle did not change obviously with the increasing ages. A tendency of L1 shifting backward was noted in the age groups of 40 to 60 and above 60 years old. The sagittal lumbosacral curves can be easily reconstructed by digitizing lateral radiographs, The aging changes of lumbosacral curves could be qualitatively described as the flattening of lower lumbar curve and the rearward inclination of upper lumbar curve. The changes occurred obviously above 40 years old. Although individual variations existed, the aging changes and the geometric characteristics such as the most anteriorward or horizontal vertebrae could be used as an important guideline during therapy or surgical correction.

The purpose of this study was to evaluate the effects of diosgenin on the D-galactose-induced cerebral cortical widely dispersed apoptosis. Male 12-week-old Wistar rats were divided into four groups: Control (1mg/kg/day of saline, i.p.), DD0 (150mg/kg/day of D-galactose, i.p.), DD10, and DD50 (D-galactose$+10$ or 50mg/kg/day of diosgenin orally). After eight weeks, histopathological analysis, positive TUNEL and Western blotting assays were performed on the excised cerebral cortex from all four groups. The TUNEL-positive apoptotic cells, the components of Fas pathway (Fas, FADD, active caspase-8 and active caspase-3), and mitochondria pathway (t-Bid, Bax, cytochrome $c$, active caspase-9 and active caspase-3) were increased in the DD0 group compared with the control group, whereas they were decreased in the DD50 group. The components of survival pathway (p-Bad, Bcl-2, Bcl-xL, IGF-1, p-PI3K and p-AKT) were increased in the DD50 group compared to the control group, whereas the levels of Bcl-xL, p-PI3K, and p-AKT were also compensatorily increased in the DD0 group compared to the control group. Taken together, diosgenin suppressed D-galactose-induced neuronal Fas-dependent and mitochondria-dependent apoptotic pathways and enhanced the Bcl-2 family associated pro-survival and IGF-1-PI3K-AKT survival pathways, which might provide neuroprotective effects of diosgenin for prevention of the D-galactose-induced aging brain.

Precipitation hardening is an effective way to improve the functional stability of NiTi shape memory alloys. The precipitates, mainly Ni₄Ti₃, could be introduced by aging treatment in Ni-rich NiTi alloys. However, the presence of Ni₄Ti₃ precipitates could disturb the transformation behavior, resulting in the multi-stage martensitic transformation (MMT). With the presence of MMT, it is difficult to control the transformation behavior, and thus limits the applicability of NiTi alloys. In this work, previous efforts on explaining the observed MMT are summarized. The difficulties in developing a unified explanation are discussed, and a possible way to avoid the MMT is proposed.

Rotation of the cervical spine beyond its normal range of motion is a leading cause of fall-related spinal cord injuries (SCIs) in older adults. This rotation is constrained, in part, by the spinal ligaments. The experimentally measured properties of these ligaments are tabulated in literature, including sex-specific properties; however, their influence on the rotation kinematics of the cervical spine has not been compared. We examined how different mechanical properties of spinal ligaments, including sex-specific properties, affected the rotational kinematics of the cervical spine using finite element analysis (FEA). Ligament properties most influenced the rotation of the lower cervical spine, with increased ligament stiffness reducing rotation. Ligament deformation remained mostly in the toe region of their force-displacement curves, emphasizing the need to incorporate non-linear ligament behavior in FEA. Predictions made using one set of experimental properties (Property 1) better-matched experimental kinematic data. Using sex-specific properties had a moderate effect (6% in extension, –3% in flexion) on rotation, with a greater impact on extension. Ligament properties also affected the segmental distribution of rotation, causing a variability of 3–21% at different levels. We emphasized the need to incorporate tailored approaches to FEA to obtain clinically relevant results when modeling flexion/extension rotation.