<p>Research suggests that physiological stress reactions may be reduced by visual impressions from natural environments as compared to urban or built-up environments. The present experiment tested whether similar effects might be found by auditory stimulation. Forty university students were tested in an experiment with four consecutive recovery sessions after stressful mental arithmetic tests. The independent variables were type of sound during recovery. The sound was either a natural sound environment (sounds from water and birdsong, at 50 dBA), or three types of noisy environments (traffic noises at 50 or 80 dBA or ambient background sound at 40 dBA). The main dependent variables were physiological recovery from stress, as measured by decrease in heart rate (HR) and skin conductance level (SCL) after the stressful arithmetic test. The main result was that SCL reduction was faster during nature sounds than during the various noises. For HR, no systematic effects of experimental sounds were found. The result for SCL lends some support the hypothesis that exposure to natural sounds facilitate physiological stress recovery.</p> / Sarcade

Research suggests that physiological stress reactions may be reduced by visual impressions from natural environments as compared to urban or built-up environments. The present experiment tested whether similar effects might be found by auditory stimulation. Forty university students were tested in an experiment with four consecutive recovery sessions after stressful mental arithmetic tests. The independent variables were type of sound during recovery. The sound was either a natural sound environment (sounds from water and birdsong, at 50 dBA), or three types of noisy environments (traffic noises at 50 or 80 dBA or ambient background sound at 40 dBA). The main dependent variables were physiological recovery from stress, as measured by decrease in heart rate (HR) and skin conductance level (SCL) after the stressful arithmetic test. The main result was that SCL reduction was faster during nature sounds than during the various noises. For HR, no systematic effects of experimental sounds were found. The result for SCL lends some support the hypothesis that exposure to natural sounds facilitate physiological stress recovery. / Sarcade

Nature and greenspaces have been enjoyed throughout history and used for relaxation purposes. Several theories, such as biophilia and stress recovery theory, suggest nature’s ability to improve stress recovery. Even though stress helps detect danger and enhances alertness, it causes fatigue and distortive cognitive functions if prolonged. Nature-based intervention such as Shinrin-yoku or forest bathing, which refers to relaxing walks in forest environments, has been recently researched and used to reduce stress in individuals. The current study is an experimental study aimed at whether attendance in nature is beneficial for stress recovery. Ten subjects were divided into an experimental group (walks in nature) and a control group (walks in a city environment). They were tested for stress levels using heart rate variability (HRV) and the Karolinska exhaustion disorder scale (KEDS) before and after the walks. The result demonstrated no significant differences in stress recovery for both measurements before and after walks in nature compared to walks in a city environment. Despite that, it did not reject nature’s positive impact on stress recovery. Therefore more research on nature-based intervention and stress recovery is required.

Composite laminates are increasingly being used as primary load bearing members in<br />structures.  However, because of the directional dependence of the properties of<br />composite materials, additional failure modes appear that are absent in<br />homogeneous, isotropic materials.  Therefore, a stress analysis of a composite<br />laminate is not complete without an accurate representation of the transverse<br />(out-of-plane) stresses.<br /><br />Stress recovery is a common method to estimate the transverse stresses from a<br />plate or shell analysis.  This dissertation extends stress recovery to problems<br />in which geometric nonlinearities, in the sense of von K\\\'rm\\\'{a}n,  are<br />important.  The current work presents a less complex formulation for the stress<br />recovery procedure for plate geometries, compared with other implementations,<br />and results in a post-processing procedure which can be applied to data from<br />any plate analyses; analytical or numerical methods, resulting in continuous or<br />discretized data.<br /><br />Recovered transverse stress results are presented for a variety of<br />geometrically nonlinear example problems: a semi-infinite plate subjected to<br />quasi-static transverse and shear loading, and a finite plate subjected to both<br />quasi-static and dynamic transverse loading.  For all cases, the corresponding<br />results from a fully three-dimensional stress analysis are shown alongside the<br />distributions from the stress recovery procedure.  Good agreement is observed<br />between the stresses obtained from each method for the cases considered.<br />Discussion is included regarding the applicability and accuracy of the<br />technique to varying plate geometries and varying degrees of nonlinearity, as<br />well as the viability of the procedure in replacing a three-dimensional<br />analysis in regard to the time required to obtain a solution.<br /><br />The proposed geometrically nonlinear stress recovery procedure results in<br />estimations for transverse stresses which show good correlation to the<br />three-dimensional finite element solutions.  The procedure is accurate for<br />quasi-static and dynamic loading cases and proves to be a viable replacement<br />for more computationally expensive analyses. / Ph. D.

Flertalet studier har visat att grönområden främjar människors fysiska och psykiska hälsa. I takt med en ökad urbanisering och stadsutbyggnad ersätts naturliga miljöer med bebyggelse vilket påverkar befolkningen i urbana miljöer negativt, eftersom urbana grönområden genererar viktiga ekosystemtjänster. En urban livsstil kan dessutom medföra hälsorisker som psykisk ohälsa, hjärt-kärlsjukdomar och fysisk inaktivitet. Syftet med uppsatsen var att genom en kvalitativ ansats undersöka vilken betydelse urbana grönområden har haft för enskilda invånare i Helsingborg under covid-19-pandemin. Tio kvalitativa e-postintervjuer genomfördes och empirin analyserades med en induktiv ansats. Uppsatsens teoretiska ramverk bestod av Attention restoration theory samt Stress recovery theory och den insamlade empirin gav upphov till följande teman: lugn och ro, hämta energi, samt miljöombyte. Resultatet visar att urbana grönområden har betydelse för informanternas hälsa, eftersom urbana grönområden bidrar till återhämtning och stressminskning, vilket är betydande faktorer för en god fysisk och psykisk hälsa. Utifrån studiens resultat kan slutsatsen dras att genom att bevara urbana grönområden kanmänniskors livskvalitet öka eftersom urbana grönområden bidrar till bättre fysisk och psykisk hälsa i samhället. / Former studies have shown that urban green spaces improve physical and mental health.Urbanisation and urban development result in green environments being replaced by buildings. This has a negative effect on urban residents as urban green spaces provide important ecosystem services. An urban lifestyle can involve health risks such as mental illness, cardiovascular disease, and physical inactivity. This study aimed to investigate through a qualitative approach, the importance of urban green spaces for individual residents of Helsingborg during the covid-19 pandemic. Ten qualitative e-mail interviews were conducted, and the empirical findings were analyzed with an inductive approach. The collected empirics resulted in the following themes: peace and quiet, gain energy, and change of scenery. The results were analyzed through the theoretical framework Attention restoration theory and Stress recovery theory. The results showed that urban green spacesare essential for the informant’s health, as they contribute to recovery and stress reduction, which are significant factors for good physical and mental health. The main conclusion of this study shows that by preserving urban green spaces, people’s quality of life can increase as urban green spaces contribute to better physical and mental health in society.

Master of Landscape Architecture / Department of Landscape Architecture/Regional & Community Planning / Brent Chamberlain / The purpose of this research is to identify if virtual reality environments with varying degrees of exposure to nature influence stress recovery at different rates. In 1991, environmental psychologist and architect, Rodger Ulrich, conducted a study on how varying degrees of exposure to nature influences stress recovery by showing participants videos with different levels of nature. His research concluded that participants who viewed the tapes containing scenes with higher degrees of nature recovered from stress quicker than those shown the tapes with higher degrees of human intervention. To expand on this research, it is important to understand how different mediums influence stress recovery. In particular, analyzing how fully immersive virtual reality environments influence the amount of time it takes to recover from a stressor. Virtual reality is particularly beneficial for testing as it enables variable isolation and complete environmental control. A test similar to Ulrich’s was conducted in three parts, a baseline, a stressor, and a stress recovery period. Two environments with varying degrees of human intervention were tested. The virtual reality environments were strategically designed along a same path to minimize the addition of extraneous variables. During this test, biometric data was taken in addition to stated stress levels and stated affective response. The study concluded that regardless of the environment type, participants lowered their baseline stress level. This study represents one of the firsts of its type and can serve as a valuable learning mechanism for testing in virtual reality. Results show promise for mitigating stress levels. However, it is recommended that a similar study be replicated in a more refined manor. Lessons learned from this study could be used to inform future studies investigating the effect of VR environments on stress and mental health.

No description available.

Selective attention to dysphoric stimuli is hypothesized to contribute to the onset and maintenance of emotional disorders. Over the past two decades, research on training and modifying attention as a form of treatment for anxiety and depression, Attentional Bias Modification (ABM) treatment, has increased exponentially. ABM has been employed in research and clinical settings with varying levels of success due to vast heterogeneity among studies. The primary aims of the present study were to examine the effects of different training contingencies, stimulus pairs, and moderators (baseline attentional bias, self-report trait anxiety, and attentional control) on stress reactivity and recovery. Undergraduates (N = 376) were randomly assigned to one of five conditions: four attention conditions each unique in training contingency and stimulus pair, and one control condition. Participants completed self-report measures, a pre-assessment of attention, one of the five conditions, a post-assessment of attention, and a stress induction. Results suggest stimulus types in AMB paradigms have a greater impact on stress responses relative to training contingencies. Participants with high levels of anxiety showed reduced stress recovery after conditions with negative stimuli. Participants with high levels of depression showed less stress reactivity after conditions with emotional stimuli. Attentional control and trait anxiety moderated stress responses. The current findings may be important in advancing ABM treatment by highlighting the significance of including emotional stimuli in ABM paradigms and tailoring treatment with baseline characteristics.

In this study, Ritz method has been employed to analyze the following problems: free vibrations of plates with curvilinear stiffeners, the lowest 100 frequencies of thick isotropic plates, free vibrations of thick quadrilateral laminates and free vibrations and static deformations of rectangular laminates, and sandwich structures. Admissible functions in the Ritz method are chosen as a product of the classical Jacobi orthogonal polynomials and weight functions that exactly satisfy the prescribed essential boundary conditions while maintaining orthogonality of the admissible functions. For free vibrations of plates with curvilinear stiffeners, made possible by additive manufacturing, both plate and stiffeners are modeled using a first-order shear deformation theory. For the thick isotropic plates and laminates, a third-order shear and normal deformation theory is used. The accuracy and computational efficiency of formulations are shown through a range of numerical examples involving different boundary conditions and plate thicknesses. The above formulations assume the whole plate as an equivalent single layer. When the material properties of individual layers are close to each other or thickness of the plate is small compared to other dimensions, the equivalent single layer plate (ESL) theories provide accurate solutions for vibrations and static deformations of multilayered structures. If, however, sufficiently large differences in material properties of individual layers such as those in sandwich structure that consists of stiff outer face sheets (e.g., carbon fiber-reinforced epoxy composite) and soft core (e.g., foam) exist, multilayered structures may exhibit complex kinematic behaviors. Hence, in such case, C_z⁰ conditions, namely, piecewise continuity of displacements and the interlaminar continuity of transverse stresses must be taken into account. Here, Ritz formulations are extended for ESL and layerwise (LW) Nth-order shear and normal deformation theories to model sandwich structures with various face-to-core stiffness ratios. In the LW theory, the C⁰ continuity of displacements is satisfied. However, the continuity of transverse stresses is not satisfied in both ESL and LW theories leading to inaccurate transverse stresses. This shortcoming is remedied by using a one-step well-known stress recovery scheme (SRS). Furthermore, analytical solutions of three-dimensional linear elasticity theory for vibrations and static deformations of simply supported sandwich plates are developed and used to investigate the limitations and applicability of ESL and LW plate theories for various face-to-core stiffness ratios. In addition to natural frequency results obtained from ESL and LW theories, the solutions of the corresponding 3-dimensional linearly elastic problems obtained with the commercial finite element method (FEM) software, ABAQUS, are provided. It is found that LW and ESL (even though its higher-order) theories can produce accurate natural frequency results compared to FEM with a considerably lesser number of degrees of freedom. / Doctor of Philosophy / In everyday life, plate-like structures find applications such as boards displaying advertisements, signs on shops and panels on automobiles. These structures are typically nailed, welded, or glued to supports at one or more edges. When subjected to disturbances such as wind gusts, plate-like structures vibrate. The frequency (number of cycles per second) of a structure in the absence of an applied external load is called its natural frequency that depends upon plate's geometric dimensions, its material and how it is supported at the edges. If the frequency of an applied disturbance matches one of the natural frequencies of the plate, then it will vibrate violently. To avoid such situations in structural designs, it is important to know the natural frequencies of a plate under different support conditions. One would also expect the plate to be able to support the designed structural load without breaking; hence knowledge of plate's deformations and stresses developed in it is equally important. These require mathematical models that adequately characterize their static and dynamic behavior. Most mathematical models are based on plate theories. Although plates are three-dimensional (3D) objects, their thickness is small as compared to the in-plane dimensions. Thus, they are analyzed as 2D objects using assumptions on the displacement fields and using quantities averaged over the plate thickness. These provide many plate theories, each with its own computational efficiency and fidelity (the degree to which it reproduces behavior of the 3-D object). Hence, a plate theory can be developed to provide accurately a quantity of interest. Some issues are more challenging for low-fidelity plate theories than others. For example, the greater the plate thickness, the higher the fidelity of plate theories required for obtaining accurate natural frequencies and deformations. Another challenging issue arises when a sandwich structure consists of strong face-sheets (e.g., made of carbon fiber-reinforced epoxy composite) and a soft core (e.g., made of foam) embedded between them. Sandwich structures exhibit more complex behavior than monolithic plates. Thus, many widely used plate theories may not provide accurate results for them. Here, we have used different plate theories to solve problems including those for sandwich structures. The governing equations of the plate theories are solved numerically (i.e., they are approximately satisfied) using the Ritz method named after Walter Ritz and weighted Jacobi polynomials. It is shown that these provide accurate solutions and the corresponding numerical algorithms are computationally more economical than the commonly used finite element method. To evaluate the accuracy of a plate theory, we have analytically solved (i.e., the governing equations are satisfied at every point in the problem domain) equations of the 3D theory of linear elasticity. The results presented in this research should help structural designers.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23860号 / 工博第4947号 / 新制||工||1773(附属図書館) / 京都大学大学院工学研究科都市社会工学専攻 / (主査)教授 岸田 潔, 教授 三村 衛, 教授 木村 亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM