Browsing by Subject "Time"

Background

Methodology/principal findings

Conclusions/significance

Phase correction has the potential to increase the image quality of real-time 3D (RT3D) ultrasound, especially for transcranial ultrasound. Such improvement would increase the diagnostic utility of transcranial ultrasound, leading to improvements in stroke diagnosis, treatment, and monitoring. This work describes the implementation of the multi-lag least-squares cross-correlation and partial array speckle brightness methods for static and moving targets and the investigation of contrast-enhanced (CE) RT3D transcranial ultrasound.

The feasibility of using phase aberration correction with 2D arrays and RT3D ultrasound was investigated. Using the multi-lag cross-correlation method on electronic and physical aberrators, we showed the ability of 3D phase aberration correction to increase anechoic cyst identification, image brightness, contrast-to-noise ratio (CNR), and, in 3D color Doppler experiments, the ability to visualize flow. With a physical aberrator, CNR increased by 13%, while the number of detectable cysts increased from 4.3 to 7.7.

We performed an institutional review board (IRB) approved clinical trial to assess the ability of a novel ultrasound technique, namely RT3D CE transcranial ultrasound. Using micro-bubble contrast agent, we scanned 17 healthy volunteers via a single temporal window and 9 via the sub-occipital window and report our detection rates for the major cerebral vessels. In 82% of subjects, we identified the ipsilateral circle of Willis from the temporal window, and in 65% we imaged the entire circle of Willis. From the sub-occipital window, we detected the entire vertebrobasilar circulation in 22% of subjects, and in 50% the basilar artery.

We then compared the performance of the multi-lag cross-correlation method with partial array reference on static and moving targets for an electronic aberrator. After showing that the multi-lag method performs better, we evaluated its performance with a physical aberrator. Using static targets, the correction resulted in an average contrast increase of 22.2%, compared to 13.2% using moving targets. The CNR increased by 20.5% and 12.8%, respectively. Doppler signal strength and number of Doppler voxels increased, by 5.6% and 14.4%, respectively, for the static method, and 9.3% and 4.9% for moving targets.

We performed two successful in vivo aberration corrections. We used this data and measure the isoplanatic patch size to be an average of 10.1°. The number of Doppler voxels increased by 38.6% and 19.2% for the two corrections. In both volunteers, correction enabled the visualization of a vessel not present in the uncorrected volume. These results are promising, and could potentially have a significant impact on public health.

Lastly, we show preliminary work testing the feasibility of a unique portable dedicated transcranial ultrasound system capable of simultaneous scanning from all three acoustic windows. Such a system would ideally be used in a preclinical setting, such as an ambulance.

Consumers are increasingly being encouraged to engage in consumption with the specific intention of improving their own emotional well-being (called “self-gifting consumption”). As a result, the market around self-care and self-gifting has been growing over the last several years. At the same time, however, consumers are also experiencing what has been called a “time famine,” or the sense of not having enough time to accomplish what they need or want to do. Leveraging the academic literatures on self-gifting consumption and time perceptions, this dissertation explores this tension, its psychological underpinnings, and possible solutions. Specifically, two essays explore antecedents of consumer interest in self-gifting, consequences of engaging in self-gifting, and the role of time perceptions in shaping these relationships.

Essay 1 examines the role of perceived time availability in driving consumers’ attitudes toward “self-gifting appeals,” or marketing appeals that communicate the intention to improve one’s emotional well-being through the purchase or consumption of a given offering. Six studies reveal that perceiving time as more (vs. less) abundant leads consumers to resonate more with self-gifting appeals, compared to when the same offerings are positioned in other ways. This occurs because perceived time abundance triggers a heightened sense of contentment—a positive, emotion-like state of feeling complete, and characterized by a desire to focus on one’s emotions—which, in turn, increases attitudes towards appeals that involve a personal, emotional focus (as with self-gifting appeals).

Turning from antecedents to consequences, Essay 2 tests whether engaging in a brief self-gifting experience provides emotional well-being benefits, whether consumers can correctly intuit this outcome, and the potential moderating role of time perceptions. Four studies demonstrate that, despite consumers’ expectations that time scarcity will hamper their ability to derive emotional benefit from self-gifting experiences, time- scarce consumers in fact derive amplified emotional well-being boosts, relative to time- abundant consumers. In addition to improving emotional well-being, self-gifting experiences can also expand one’s sense of available time, particularly for the time-scarce.

Overall, this dissertation contributes to the literatures on time perceptions, self- gifting, affective forecasting, and consumer well-being and has implications for the role that consumption and marketing can play in improving consumers’ lives.

Background

Objectives

Methods

Results

Conclusions

Consumers often have multiple goals and limited time to pursue them. Running out of time means that people may fail to achieve, or to even attempt, one or more valued goals. When time constrains multiple goal pursuit, what might encourage consumers to protect time for downstream goals (i.e., goals that occur later in a sequence)? I propose that a subtle shift in the way people think about setting multiple goals in relation to limited time can help. Nine experiments demonstrate that, compared to only setting goals, budgeting time first (i.e., allocating total time across tasks before specifying goal levels) encourages people to set more realistic (i.e., more accurate) multiple goals that better fit within the total available time. This occurs because, by disaggregating the total time available for multiple goals into distinct accounts, budgeting time reduces implicit “double dipping” into a shared time pool when setting goals. By encouraging people to set more realistic upstream goals, budgeting time first increases time spent on downstream goals, boosting how much people accomplish toward, and whether they ultimately achieve, those goals. Further, by protecting time for downstream goals, budgeting time first discourages consumers from exceeding the total time budget and spending against future periods. This research contributes to understanding of the relationship between goals and time, multiple goal setting and pursuit, and mental accounting and budgeting. The findings also have substantive implications for consumer goal pursuit and well-being.

As a work of Christian dogmatic theology, this dissertation proceeds from the primary theological claim that human existence in time is determined by the incarnation, passion, resurrection, and ascension of Jesus Christ. It also examines how the predominant accounts of time in the modern West have been affected by, and produced by, claims of scientific authority. The implications of these accounts are not only a matter of abstract doctrinal and philosophical reflection. Instead, they have had, and continue to have, concrete ramifications for human life together. They have been death-dealing rather than life-giving, characterized by a set of temporal pathologies that participate at the deepest level in marking some lives as expendable.

There are four particular pathologies that this project addresses in turn. The first is the mystification of theology by questions of human origins, especially as those questions are addressed by figures of scientific authority. The second is the problem of progress and politicized eschatology, in which securing a desired vision of the future becomes a human project. The third is temporal distancing, in which some human beings are marked as temporally retrograde or outside of history. The fourth, and final, problem addressed is the Hegelian perspective outside of time from which time is evaluated.

This dissertation offers a set of Christological temporal recalibrations through a reading of Søren Kierkegaard and Karl Barth, highlighting the ways that both figures rejected an approach to time that is not coincidentally intertwined with a racialized account of history, and with the co-opting of Christianity by the modern Western state. It also suggests how the liturgical calendar may, and may not, provide Christians with the formational resources to think differently about their own time, and about their neighbors.

This dissertation attempts to do two things. First, I provide a theological interpretation of congregation-based community organizing by connecting this activity to the politics of the church. The link between the two, I argue, is the rule of Christ, a non-hierarchical process of political judgment that operates in a mode of receptive generosity and vulnerability as well as accountability to deliberate and discern how best to resolve conflicts. Situating this activity within an apocalyptic orientation determined by lordship of Jesus Christ, I suggest that this process, when accompanied by the other structuring practices of the church, allows the social, historical community to embody the new age of God's reign. Congregation-based community organizing, I conclude, is the extension and extrapolation of this constitutive process, and therefore, can be understood as an act of mission in witness and service to the world. In addition, this missionary activity can also help to retool the church in the practice of binding and loosing, which has fallen into desuetude. Second, I describe how this missionary activity functions both faithfully and effectively to challenge and counteract the forces of late, global capital. By challenging the configuration and experience of time under capital, the work of organizing can serve to recover political judgment from a regnant market ideology so as to reconstitute the way decisions are made and conflicts resolved by opening them to a process more lilted to the justice of God's reign. Moreover, in doing so, the political work of organizing can serve to offer a new future through forgiveness and reconciliation to individuals and a society trapped within a capitalist history whose end is immanently experienced in the destructive pursuit of unlimited growth and expansion.

This dissertation uses the lens of cultural sociology to understand variance in people’s attitude reports over time. Across three studies, I use a variety of panel surveys and statistical approaches to understand how and why people change their attitudes and adjudicate theories of culture. Study 1 uses data from the 2006 to 2014 rotating panels of the General Social Survey to adjudicate between a settled dispositions model, in which changes in attitudes are temporary and people return to a settled baseline, and an active updating model, where changes persist. Study 2 explores heterogeneity within the settled dispositions group, asking whether people’s attitude reports should be thought of as temporary constructs drawn from stored considerations or whether they represent durable opinions. It quantifies the prevalence of these opinion behaviors for 544 items from 10 panel data sets. Study 3 seeks to predict variance in attitude responses over time. Using data on religious, moral, and family structure beliefs in the National Study of Youth and Religion, I use Latent Class Analysis to deduce a set of constraints that should shape people’s response patterns over time. I test these constraints on people’s subsequent attitude reports. Taken together, results of these studies suggest 1) people’s attitudes are stable, on average, over the long term; 2) this average stability often masks high levels of instability in the short term, though some proportion of the population is stable on any issue; and 3) both this stability and instability are somewhat predictable based on a person’s pattern of beliefs. Findings suggest a model of culture where people internalize a diverse set of considerations when they are young and are shaped, in the short-term, by environmental influences. But durable cognitive structures, likely formed when people are young, limit the power of changing social circumstances to induce durable change.