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Although a significant amount of research has focused on traditional media choice and use, and even on some ‘new’ media, these studies have either neglected the Internet and World Wide Web or were conducted prior to their recent popularity. This study offers a novel exploration of individuals' use of three Internet functions (information retrieval, information giving, and conversation capabilities) in the context of the use of other communication media. Data from 684 individuals demonstrate that the Internet is a multidimensional technology used in a manner similar to other, more traditional media. Specifically, conversation features of the Internet align with mediated interpersonal technologies (the telephone and electronic mail), whereas the Internet's information‐retrieval and information‐giving features are used in ways similar to mass media channels (newspapers, television, and books and magazines). In addition, needs fulfilled by these channels cluster in ways consistent with past research, regardless of the technologies employed to meet them.  相似文献   
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Public goods theories highlight an incentive system that rewards ‘free riding’ on the contributions of early contributors toward collective actions. However, because such theories focus on creation of the good, they may underestimate returns that accrue to early contributors subsequent to the good's realization. The concept of formative investment is introduced here to describe the extent to which organizations help to create public goods such as interorganizational linkages like participatory federations. Data from the CEOs of 48 organizations involved in a participatory federation were used to assess how an organization's level of formative investment is related to later patterns of dependency and interaction among federation members. Findings suggest that from a long‐term perspective, and for goods that involve communication and interaction, the incentive structure may not be so favorable for free riders. To the extent that organizations with high formative investment have the capability to envision the future and communicate that vision to potential federation partners, they may be able to both reduce free riding and secure for themselves advantageous positions in the subsequent network of relations.  相似文献   
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Molecular sequence data, made available in the last 15 years or so, have led to the classification of living cells into three phylogenetic domains: Bacteria, Archaea, and Eucarya. All the organisms that have been tested belonging to either domain were capable of mounting a stress response with essentially the same characteristics, regardless of the stressor. The protagonists in the cell's stress response are the stress genes and their protein products. Some of the latter are molecular chaperones. Under physiological conditions, these chaperones aid other cellular proteins to fold properly and achieve a native -functional- configuration, and to translocate from the place of synthesis to the cell's locale in which they will operate. In a stressed cell, the stress proteins that are chaperones protect other molecules from denaturation and help those partially damaged to regain a functional configuration. Thus, cell death is avoided and recovery is enhanced. The study of stress genes and proteins has progressed considerably in organisms belonging to the domains Bacteria and Eucarya. Less is known about the archaeal stress genes. Here, research with an organism from the Archaea is discussed, focusing on the stress genes of the hsp70 (dnaK) locus. Future perspectives for basic and applied research within the health sciences and biotechnology industries are presented.  相似文献   
4.
Although children born preterm or low birth weight (PT LBW) are more likely to exhibit behavior problems compared to children born at term, developmental and family processes associated with these problems are unclear. We examined trajectories of maternal depressive symptoms in relation to toddler compliance and behavior problems in families with PT LBW infants. A total of 177 infants (93 boys, 84 girls) and their mothers enrolled in the study during the infant's NICU stay. Data were collected at five time points across 2 years. Assessments of maternal depressive symptoms were conducted at all time points, and toddler compliance and opposition to maternal requests and behavior problems were assessed at 2 years. Toddlers born earlier with more health problems to mothers whose depressive symptoms increased over time exhibited the most opposition to maternal requests during a cleanup task at 24 months, consistent with multiple risk models. Mothers with elevated depression symptoms reported more behavior problems in their toddlers. The study has implications for family‐based early intervention programs seeking to identify PT LBW infants at highest risk for problem behaviors.  相似文献   
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Thresholds in various visual and auditory perception tasks have been found to improve markedly with practice at intermediate levels of task difficulty. Recently, however, there have been reports that training with identical stimuli, which, by definition, were impossible to discriminate correctly beyond chance, could induce as much discrimination learning as could training with different stimuli. These surprising findings have been interpreted as evidence that discrimination learning can occur in the absence of perceived differences between stimuli and need not involve the fine-tuning of a discrimination mechanism. Here, we show that these counterintuitive findings of discrimination learning without discrimination can be understood simply by considering the effect of internal noise on sensory representations. Because of such noise, physically identical stimuli are unlikely to be perceived as being strictly identical. We show that, given empirically derived levels of sensory noise, perceived differences evoked by identical stimuli are actually not much smaller than those induced by the physical differences typically used in discrimination-learning experiments. We suggest that findings of discrimination learning with identical stimuli can be explained without implicating any fundamentally new learning mechanism.  相似文献   
6.
Innovation adoption research has demonstrated that organizational features and perceived benefits of innovations play significant roles in explaining organizational‐level decisions to adopt new technologies. Beyond such motivations, however, social pressures operating at the interorganizational level have been proposed to influence the decision to adopt innovations, even without regard to any proven or anticipated benefit from the innovation itself. To empirically determine the influence of organizational features, perceived benefits, and social pressures on organizations' innovation adoption decisions, this study examined the decisions of 288 organizations to adopt Internet websites. Organizational social pressures were found to be the most significant discriminators of adopters and non adopters, although they were not particularly important in predicting the likelihood of future adoption for those organizations currently without websites. This finding suggests that social pressures are significant in innovation adoption, but that they may have their strongest effect during the early phases of innovation diffusion. Organizational features and perceived benefits were also reasonable discriminators of adopters and nonadopters as well as effective predictors of the likelihood of adoption for nonadopters. To a lesser degree, these factors were also predictive of the stage of adoption for those organizations that have already adopted websites.  相似文献   
7.
Pitch, the perceptual correlate of fundamental frequency (F0), plays an important role in speech, music, and animal vocalizations. Changes in F0 over time help define musical melodies and speech prosody, while comparisons of simultaneous F0 are important for musical harmony, and for segregating competing sound sources. This study compared listeners' ability to detect differences in F0 between pairs of sequential or simultaneous tones that were filtered into separate, nonoverlapping spectral regions. The timbre differences induced by filtering led to poor F0 discrimination in the sequential, but not the simultaneous, conditions. Temporal overlap of the two tones was not sufficient to produce good performance; instead performance appeared to depend on the two tones being integrated into the same perceptual object. The results confirm the difficulty of comparing the pitches of sequential sounds with different timbres and suggest that, for simultaneous sounds, pitch differences may be detected through a decrease in perceptual fusion rather than an explicit coding and comparison of the underlying F0s.  相似文献   
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