This thesis investigated the role of interference in general cognitive functioning. Study 1 explored the relationships among interference control, memory, and fluid intelligence. Studies 2 and 3 explored the possibility that interference is controlled by suppressing the interfering information rather than, for example, facilitating the target information. Study 1 tested the hypothesis that individual differences in the ability to regulate interference are responsible for the correlation between memory tasks and fluid intelligence. Participants completed common measures of working memory, long-term memory, fluid intelligence, and interference regulation. In structural equation models, controlling for interference regulation ability largely accounted for the correlation between the memory tasks and fluid intelligence. These results suggest that efficient interference control is critical to cognitive functioning. Study 2a tested the hypothesis that interference is regulated by suppressing competing responses. In Phase 1 of a three-phase paradigm, participants performed a vowel-counting task that included pairs of orthographically similar words (e.g., allergy/analogy). In Phase 2 participants solved word fragments (e.g., a _ l _ _ gy) that resembled both words in an earlier pair, but could be completed only by one of these words. Phase 3 measured the consequence of having resolved interference in Phase 2 by asking participants to read a list of words, including the rejected competitors, as quickly as possible. Relative to participants in control conditions that did not require interference resolution these interference condition participants were slower to name competitor words. Study 2b showed that while competitors are suppressed during interference resolution, a complementary facilitative process does not directly enhance accessibility of targets. Finally, Study 3 tested the hypothesis that older adults have impaired suppression abilities. Older adults were tested in the same paradigm used in Studies 2a and 2b. In contrast to younger adults, older adults showed no suppression of competitors. This result supports the theory that some age related memory deficits stem from impaired suppression processes.

There is evidence to suggest that people from different cultures have different cognitive processing styles. For example, by measuring the eye movements of American and Chinese students when viewing pictures, Chua, Boland, and Nisbett (2005) found that American students fixated more on the focal object, whereas Chinese students fixated more on the background. In a subsequent object-recognition task, the Chinese students were less likely to correctly recognize old objects presented in new backgrounds than Americans did. This study used a similar scene-viewing task to investigate whether aging modulates these cultural differences in cognitive processing style. Like Chua et al., we found that young Chinese students spent longer fixating the background than did their Western counterparts. However, we failed to replicate the accompanying memory bias observed by Chua et al. Our strongest finding was that maintaining the original background facilitated memory for objects in young participants of both cultures but not for older participants. This result suggests that older adults had poorer memory for background details and/or had poorer integration of object and background.

This thesis investigated the role of interference in general cognitive functioning. Study 1 explored the relationships among interference control, memory, and fluid intelligence. Studies 2 and 3 explored the possibility that interference is controlled by suppressing the interfering information rather than, for example, facilitating the target information. Study 1 tested the hypothesis that individual differences in the ability to regulate interference are responsible for the correlation between memory tasks and fluid intelligence. Participants completed common measures of working memory, long-term memory, fluid intelligence, and interference regulation. In structural equation models, controlling for interference regulation ability largely accounted for the correlation between the memory tasks and fluid intelligence. These results suggest that efficient interference control is critical to cognitive functioning. Study 2a tested the hypothesis that interference is regulated by suppressing competing responses. In Phase 1 of a three-phase paradigm, participants performed a vowel-counting task that included pairs of orthographically similar words (e.g., allergy/analogy). In Phase 2 participants solved word fragments (e.g., a _ l _ _ gy) that resembled both words in an earlier pair, but could be completed only by one of these words. Phase 3 measured the consequence of having resolved interference in Phase 2 by asking participants to read a list of words, including the rejected competitors, as quickly as possible. Relative to participants in control conditions that did not require interference resolution these interference condition participants were slower to name competitor words. Study 2b showed that while competitors are suppressed during interference resolution, a complementary facilitative process does not directly enhance accessibility of targets. Finally, Study 3 tested the hypothesis that older adults have impaired suppression abilities. Older adults were tested in the same paradigm used in Studies 2a and 2b. In contrast to younger adults, older adults showed no suppression of competitors. This result supports the theory that some age related memory deficits stem from impaired suppression processes.

Mass rural-urban migration and population aging are occurring simultaneously at a rapid speed in contemporary China. Tens of millions of rural young laborers have been migrating to urban areas to meet the demand for cheap labor, whereas large numbers of elderly parents (the Chinese baby boomers) are left behind in the impoverished villages. Consequently, adult children are becoming more and more unavailable to fulfill their elder care responsibilities. This study took a systematic look at how the increasing rural-urban migration shaped the elder care practices in rural Chinese families and how rural elders respond and adapt to this social transformation. Using data from a rural household survey conducted by Renming University in 2004 in three in-land migrant-exporting provinces, this study explored three aspects of elder-care dynamics in China: 1. The patterns of financial care for rural elders whose adult children had migrated to urban areas. 2. Rural elders’ perceptions of filial piety at this time of social change. 3. Rural elders’ self-evaluation of life satisfaction at this historical period of time. The theoretical model of Political Economy of Aging (PEA) and criticism of classic modernization theory were used to guide the generation of hypotheses and analyses of statistical data. Findings from this study revealed that financial care by migrated children was mainly based on an exchange-based model; rural elders who took care of grandchildren received more financial support. With the continued provision of financial care and emotional care, rural elders continued to hold relatively positive evaluation of their migrated children’s filial piety, even though physical care was absent. Thus, the author argued that within the context of rural-urban migration, filial piety was not undergoing decline or erosion; rather, its meanings and significance have been broadened by their elderly parents to adapt to dramatic social changes currently underway in China. Finally this study found that the exchange-based pattern of financial care and the continuation of filial piety had a positive impact on rural elders’ life satisfaction. This study contributes to the knowledge body of elder care in China and provides insightful policy suggestions for the Chinese government.

This study investigated the influence of training on interference in younger and older adults using the Eriksen flanker task. Does flanker interference differ with age and, as practice progresses, does the pattern of interference change? Younger and older adults were given five sessions of training on the flanker task over five successive days. On each trial, participants saw a central target letter flanked vertically by two flanker letters; the flankers could be either compatible or incompatible with the target. Participants were to respond to the identity of the central letter, ignoring the flanker letters. Although older adults were slower overall than younger adults in responding, the two groups showed virtually identical overall benefits from practice. Critically, the two age groups showed equivalent and constant interference due to incompatible flankers at all stages of practice. In the flanker paradigm, aging slows response execution without affecting attention within a trial or learning across trials.

We examined how explicit instructions to encode visual context information accompanying visually-presented unrelated target words affected later recognition of the targets presented alone, in younger and older adults. In Experiments 1 and 3, neutral context scenes, and in Experiments 2 and 4, emotionally salient context scenes, were paired with target words during encoding. Experiments 1 and 2 data were collected using within subject design; in Experiments 3 and 4 we used a between subjects design. Across all four experiments, instructions to explicitly make a link (associate) between simultaneously presented context and target words always led to significantly better recognition memory in both younger and older adults compared to deep or shallow levels of processing (LoP) instructions for the context information. In all experiments the age-related deficit in overall memory remained. There was no consistent difference in the effect of a shallow versus deep processing of context in the first three experiments in young adults, although a standard LoP effect, with better memory performance following deep than shallow processing, was demonstrated with both age groups in Experiment 4. Results suggest that an instruction to explicitly link target words to context information will significantly and consistently improve memory recognition for targets. This was demonstrated in all four experiments, in both younger and older adults. Importantly, results suggest that memory in older adults can be improved with specific instructional manipulations during encoding.

A large body of research has investigated various aspects of attention in normal aging and Alzheimers disease (AD). Most of the previous studies have shown that divided attention, the ability to attend to two tasks or stimuli simultaneously, declines in both normal aging and AD. In a recent study of attention, Baddeley, Baddeley, Bucks, and Wilcock (2001) reported findings that contrast with other divided attention research. Specifically, they found no effects of aging on divided attention. Taken in combination with their findings of age and AD effects on other aspects of attention, the authors concluded that age-equivalent results on divided attention tasks support the theory that attentional control should be viewed as a fractionated system. Study 1 considered methodological differences between the divided attention tasks used by Baddeley et al., and the tasks used by researchers who have reported age-related differences. Specifically, the effects of task difficulty on age effects were examined. Young, middle-aged, and older adults were compared on a dual-task procedure that combined a secondary visuomotor task (box joining) with a primary verbal task (month reciting) administered at two levels of difficulty. Results showed a significant Age x Task Difficulty interaction. That is, differences among age groups were proportionately greater in the difficult dual-task condition versus the easy condition, suggesting that age-related declines in divided attention may only be detected if tasks are sufficiently difficult.<p> Study 2 examined attention in normal aging and AD. Young adults, older adults, and early-stage AD patients were compared on tasks of selective attention, focal attention, and divided attention, with each task administered at two levels of difficulty. Similar Group x Task Difficulty interaction effects were detected for all attentional tasks, a finding which is more consistent with a general-purpose model than a fractionated model of attention. Study 3 considered attentional tasks from a clinical perspective. Specifically, the attentional tasks utilized in Study 2 were examined with respect to their ability to correctly classify individuals with early-stage AD and normal older adults. Findings showed that all attentional tasks successfully discriminated patients from cognitively healthy older adults, with one task of divided attention showing particularly impressive sensitivity and specificity. Findings of the three studies are discussed with regard to their implications for future research and clinical practice.

The joint strength and fracture surface of Sn80¢HAu20¢H and Sn20¢HAu80¢H solders in laser diode package under thermal aging testing were studied experimentally. The AuSn thin film solders were coated on the substrate by electro-plating technique. The Sn80¢HAu20¢H solder was melting point at 210¢J,while the Sn20¢HAu80¢Hsolder was melting point at 280¢J. During the processes of bonding substrate and Al2O3 together, the N2 and H2 gases were used to achieve the bonding. Then the specimens were aged at 150¢J for one, four, nine, sixteen, twenty-five, thirty-six and forty-nine days. We investigated the bonding strength, voids, IMC thickness and microstructure of the Sn80¢HAu20¢H and Sn20¢HAu80¢H solders. In addition, we also studied the comparison with the process of flux and fluxless. Under the forty-nine days of aging, the bonding strength of Sn80¢HAu20¢Hand Sn20¢HAu80¢H solders decreased from 34.3¢V to 26.0¢V and from 54.96¢V to 47.06¢V,respectively. Moreover,the IMC thickness of Sn80¢HAu20¢H and Sn20¢HAu80¢H solders increased from1.07£gm to 2.85£gm and from 0.83 £gm to 1.08 £gm, respectively. The Sn20¢HAu80¢H solders showed a better joint strength performance than Sn80¢HAu20¢H due to the less grown of IMC and superior mechanical properties of Au. The fluxless process exhibited the better joint strength performance due to the less grown of voids. In the study, by using the lead-free and fluxless process, the reliability of laser module package may be improved.

Aging is characterized by a progressive decline in cardiac function. A critical contributor to the age-related impairment in heart function is the loss of cardiac myocytes through ??apoptosis??, or programmed cell death. A dramatic increase in the rate of apoptosis has been reported with aging in the rat left ventricle. In contrast, exercise training not only improves cardiac function, but also reduces the risk of heart disease. However, the ability of exercise training to modulate apoptotic signaling and apoptosis in the aging heart remains unknown. Therefore, the purpose of this study was to determine the effects of exercise training on apoptotic signaling and apoptosis in the aging heart. We hypothesized that (1) aging would increase pro-apoptotic signaling and apoptosis in the rat left ventricle, and (2) exercise training would ameliorate upregulation of Bcl-2 family-driven apoptosis in the heart. Four and 25 month old Fischer-344 rats were assigned to four groups: young control (YC), young trained (YT), old control (OC), and old trained (OT). Exercise training groups ran on a treadmill for 60 min/day at 15 m/min (15&#730; incline), 5 d/wk for 12 wk. Protein expression of Bax, Bcl-2, caspase-9, and cleaved caspase-3 was measured using Western immunoblot analysis. Apoptosis (DNA fragmentation) was assessed using a cell death detection ELISA. Bax levels in OC were dramatically higher (+176.0%) compared to YC. In contrast, exercise training resulted in a significant decrease (-53.4%) in Bax in OT compared to OC. Bcl-2 levels in OC were lower (-26.3%) compared to YC. Conversely, exercise training significantly increased Bcl-2 levels by 117.8% in OT compared to OC. Caspase-9 levels were higher (+98.7%) in OC than YC, while exercise training significantly reduced caspase-9 levels in YT (-52.6%) and OT (-76.9%), respectively. Aging resulted in a dramatic increase (+122.8%) in cleaved caspase-3 levels and a significant decrease (-32.9%) with exercise training. Finally, apoptosis (DNA fragmentation) significantly increased (+163.8%) with aging and decreased (-43.9%) with exercise training. These novel data indicate that aging increases pro-apoptotic signaling and apoptosis in the left ventricle, while exercise training is effective in diminishing pro-apoptotic signaling and apoptosis in the aging heart.

A common maxim of protein biochemistry states, “structure is function.” This is generally just as true for an individual polypeptide chains as for multi-protein complexes. The advent of yeast tagged-protein libraries has allowed systematic screening of a protein’s local interaction partners as well as a roughly mapping its cellular location. Recently our group and others discovered hundreds proteins forming new structures in stationary phase yeast cells using the yeast GFP-tag library. That equates to well over a quarter of normally diffuse cytoplasmic proteins assembled into discrete structures that appear as foci or fibers, all of unknown function. This study provides evidence that many of these foci are formed by protein aggregation- that contrary the maxim, structure can be dysfunction. Furthermore, this study uses yeast to demonstrate the generality of cytoplasmic protein aggregation in response to a variety of stresses, provides evidence that increasing aggregation of particular cytoplasmic proteins correlates with aging even across organisms, and proposes a theoretical framework for how cellular energy levels affect protein aggregation propensity. / text