1,918 research outputs found
Self-organization and phase transition in financial markets with multiple choices
Market confidence is essential for successful investing. By incorporating
multi-market into the evolutionary minority game, we investigate the effects of
investor beliefs on the evolution of collective behaviors and asset prices.
When there exists another investment opportunity, market confidence, including
overconfidence and under-confidence, is not always good or bad for investment.
The roles of market confidence is closely related to market impact. For low
market impact, overconfidence in a particular asset makes an investor become
insensitive to losses and a delayed strategy adjustment leads to a decline in
wealth, and thereafter, one's runaway from the market. For high market impact,
under-confidence in a particular asset makes an investor over-sensitive to
losses and one's too frequent strategy adjustment leads to a large fluctuation
in asset prices, and thereafter, a decrease in the number of agents. At an
intermediate market impact, the phase transition occurs. No matter what the
market impact is, an equilibrium between different markets exists, which is
reflected in the occurrence of similar price fluctuations in different markets.
A theoretical analysis indicates that such an equilibrium results from the
coupled effects of strategy updating and shift in investment. The runaway of
the agents trading a specific asset will lead to a decline in the asset price
volatility and such a decline will be inhibited by the clustering of the
strategies. A uniform strategy distribution will lead to a large fluctuation in
asset prices and such a fluctuation will be suppressed by the decrease in the
number of agents in the market. A functional relationship between the price
fluctuations and the numbers of agents is found
Overexpression of soybean ubiquitin-conjugating enzyme gene GmUBC2 confers enhanced drought and salt tolerance through modulating abiotic stress-responsive gene expression in Arabidopsis
Previous studies have shown that ubiquitination plays important roles in plant abiotic stress responses. In the present study, the ubiquitin-conjugating enzyme gene GmUBC2, a homologue of yeast RAD6, was cloned from soybean and functionally characterized. GmUBC2 was expressed in all tissues in soybean and was up-regulated by drought and salt stress. Arabidopsis plants overexpressing GmUBC2 were more tolerant to salinity and drought stresses compared with the control plants. Through expression analyses of putative downstream genes in the transgenic plants, we found that the expression levels of two ion antiporter genes AtNHX1 and AtCLCa, a key gene involved in the biosynthesis of proline, AtP5CS, and the copper chaperone for superoxide dismutase gene AtCCS, were all increased significantly in the transgenic plants. These results suggest that GmUBC2 is involved in the regulation of ion homeostasis, osmolyte synthesis, and oxidative stress responses. Our results also suggest that modulation of the ubiquitination pathway could be an effective means of improving salt and drought tolerance in plants through genetic engineering
Lifespan Intellectual Factors, Genetic Susceptibility, and Cognitive Phenotypes in Aging: Implications for Interventions
Along with rapid global population aging, the age-related cognitive disorders such as mild cognitive impairment (MCI) and dementia have posed a serious threat to public health, health care system, and sustainable economic and societal development of all countries. In this narrative review, we seek to summarize the major epidemiological studies from the life-course perspective that investigate the influence of genetic susceptibility [e.g., apolipoprotein (APOE) ε4 allele] and intellectual or psychosocial factors (e.g., educational attainments and leisure activities) as well as their interactions on cognitive phenotypes in aging. Numerous population-based studies have suggested that early-life educational attainments and socioeconomic status, midlife work complexity and social engagements, late-life leisure activities (social, physical, and mentally-stimulating activities), certain personality traits (e.g., high neuroticism and low conscientiousness), and depression significantly affect late-life cognitive phenotypes. Furthermore, certain intellectual or psychosocial factors (e.g., leisure activities and depression) may interact with genetic susceptibility (e.g., APOE ε4 allele) to affect the phenotypes of cognitive aging such that risk or beneficial effects of these factors on cognitive function may vary by carrying the susceptibility genes. Current evidence from the randomized controlled trials that support the cognitive benefits of cognitive training among cognitive healthy older adults remains limited. The cognitive reserve hypothesis has been proposed to partly explain the beneficial effects of lifetime intellectual and psychosocial factors on late-life cognitive function. This implies that, from a life-course perspective, preventive intervention strategies targeting multiple modifiable intellectual and psychosocial factors could interfere with clinical expression of cognitive disorders in old age and delay the onset of dementia syndrome, and thus, may help achieve healthy brain aging
A generalized public goods game with coupling of individual ability and project benefit
Facing a heavy task, any single person can only make a limited contribution
and team cooperation is needed. As one enjoys the benefit of the public goods,
the potential benefits of the project are not always maximized and may be
partly wasted. By incorporating individual ability and project benefit into the
original public goods game, we study the coupling effect of the four
parameters, the upper limit of individual contribution, the upper limit of
individual benefit, the needed project cost and the upper limit of project
benefit on the evolution of cooperation. Coevolving with the individual-level
group size preferences, an increase in the upper limit of individual benefit
promotes cooperation while an increase in the upper limit of individual
contribution inhibits cooperation. The coupling of the upper limit of
individual contribution and the needed project cost determines the critical
point of the upper limit of project benefit, where the equilibrium frequency of
cooperators reaches its highest level. Above the critical point, an increase in
the upper limit of project benefit inhibits cooperation. The evolution of
cooperation is closely related to the preferred group-size distribution. A
functional relation between the frequency of cooperators and the dominant group
size is found
Relation between axial length and ocular parameters
AIM: To investigatethe relation between axial length(AL), age and ocular parameters.<p>METHODS: A total of 360 subjects(360 eyes)with emmetropia or myopia were recruited. Refraction, center corneal thickness(CCT), AL, intraocular pressure(IOP)were measured by automatic-refractor, Pachymeter, A-mode ultrasound and non-contact tonometer, respectively. Corneal curvature(CC), anterior chamber depth(ACD)and white-to-white distance(WWD)were measured by Orbscan II. Three dimensional frequency domain coherent optical tomography(3D-OCT)was used to examine the retinal nerve fiber layer thickness(RNFLT). The Pearson correlation coefficient(<i>r</i>)and multiple regression analysis were performed to evaluate the relationship between AL, age and ocular parameters.<p>RESULTS: The average AL was 24.15±1.26mm. With elongation of the AL, spherical equivalent(SE)(<i>r</i>=-0.742,<i>P</i><0.01), CC(<i>r</i>=-0.395, <i>P</i><0.01)and RNFLT(<i>r</i>=-0.374, <i>P</i><0.01)all decreased, while the mean ACD(<i>r</i>=0.411, <i>P</i><0.01)increased. On the contrary, there was not statistical significan with CCT(<i>r</i>=0.099, <i>P</i>=0.060)and WWD(<i>r</i>=0.061, <i>P</i>=0.252). There was also a significant correlation between AL and age(<i>P</i>=0.001), SE(<i>P</i><0.001), ACD(<i>P</i><0.001), CC(<i>P</i><0.001)in Multiple linear regression analysis.<p>CONCLUSION: In longer eyes, there is a tendency toward myopia, a flatter cornea, a deeper ACD and a thinner RNFLT. Age is an influencing factor for the AL as well
Identification of a new thermostable and alkali-tolerant α-carbonic anhydrase from Lactobacillus delbrueckii as a biocatalyst for CO2 biomineralization
Colorectal cancer screening with fecal occult blood test: A 22-year cohort study.
The aim of the present study was to investigate the efficacy of colorectal cancer (CRC) screening with a three-tier fecal occult blood test (FOBT) in the Chinese population. The study was performed between 1987 and 2008 at the Beijing Military General Hospital, in a cohort of army service males and females aged >50 years. Between 1987 and 2005, a three-tier screening program, comprising guaiac-based FOBTs (gFOBTs), followed by immunochemical FOBTs for positive guaiac test samples and then colonoscopy for positive immunochemical test subjects, was performed annually. The cohort was followed up until 2008. The cohort included 5,104 subjects, of which, 3,863 subjects participated in screening (screening group) and 1,241 did not (non-screening group). The two groups did not differ in age, gender or other major risk factors for colon cancer. Overall, 36 CRCs occurred in the screening group and 21 in the non-screening group. Compared with the non-screening group, the relative risk for the incidence and mortality of CRC was 0.51 [95% confidence interval (CI), 0.30-0.87] and 0.36 (95% CI, 0.18-0.71), respectively, in the screening group. The general sensitivity of this three-tier FOBT was 80.6% (95% CI, 65.3-91.1). Thus, annual screening using the three-tier FOBT program may reduce the CRC incidence and mortality rate
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