No description available.

Minimally invasive surgery (MIS) has several advantages over traditional methods. Scaling MIS instruments to smaller sizes and increasing their performance will enable surgeons to offer new procedures to a wider range of patients. In this work, two compliant mechanism-based minimally invasive surgical instrument wrist or gripper mechanisms are designed and analyzed.The cylindrical cross-axis flexural pivot (CCAFP) is a single-degree-of-freedom wrist mechanism that could be combined with existing gripper mechanisms to create a multi-degree-of freedom instrument. The simplicity of the CCAFP mechanism facilitates analysis and implementation. The flexures of the CCAFP are integral with the instrument shaft, enabling accessories to be passed through the lumen. The CCAFP is analyzed and determined to be a viable wrist mechanism for MIS instruments based on research results. A finite element (FE) model of the mechanism is created to analyze the force-deflection and strain-deflection relationships. Experimental results are used to verify the FE model. A 3 mm design is created that could undergo an angular deflection of +/- 90 degrees. The addition of cam surfaces to help guide the flexures and limit the maximum stress during deflection is explored. These cam surfaces can be integral to the instrument shaft along with the flexures. A 2 degree-of-freedom (DoF) CCAFP with intersecting axes of rotation is also introduced. The inverted L-Arm gripper compliant mechanism has 2 DoF, one wrist and one gripping. Three challenges associated with using compliant mechanisms in MIS instruments are considered: inadequate performance in compression, large flexure deformations, and a highly variable mechanical advantage. These challenges were resolved in the L-Arm design by inverting the flexures, tailoring flexure geometry and employing nitinol, and integrating pulleys into each jaw of the mechanism. The L-Arm was prototyped at several sizes to demonstrate functionality and scalability. A finite element model of the L-Arm flexure was created to determine the strain-deflection relationship. A fatigue test was completed to characterize nitinol for use in compliant mechanism MIS instruments.These concepts demonstrate the ability of compliant mechanisms to overcome the design and manufacturing challenges associated with MIS instruments at the 3 mm scale. The models and principles included in this work could be used in the application of compliant mechanisms to design new MIS instruments as well as in other areas that employ compliant mechanisms in a cylindrical form factor.

No description available.

Society requires better insights into how disturbances will alter the global carbon cycle. Ecosystem models help us understand the carbon cycle and make predictions about how the terrestrial land sink will change under future climate regimes. Disturbances drive ecosystem cycling, but modeling disturbances has unique challenges, particularly in incorporating heterogeneity and parameter uncertainty. In this dissertation, I explore two questions. 1) How can we capture disturbance ecology in models?, which I explore in my first and second chapters, and 2) How can we use those models to make projections for the Southeastern US?, which I explore in my third and fourth chapters. Both my first and second chapters point to the practical trade-offs in model structure and realism. In my first chapter, I found that representing spatially implicit contagious disturbances in terms of shape and frequency accurately captured structural changes over time and separated the disturbance regimes of different regions. Representing spatially implicit disturbances in terms of shape and frequency sacrificed the specificity of a space-based approach but may be more computationally efficient. In my second chapter, I developed a framework for calibrating models based on an iterative cycle between uncertainty analysis and literature synthesis, targeted field campaigns, and statistical constraint. I found that targeted field work and statistical constraint reduced parameter uncertainty until structural uncertainty began to dominate. Models that capture disturbance dynamics can help us anticipate effects of global change factors like climate change and invasive species. In my third chapter, I found that elevated temperatures reduce cogongrass biomass, and that cogongrass facilitates pine dominance over oaks in a mixed pine-oak stand. This suggests that cogongrass mediates inter-species competition at an ecosystem scale. Prescribed burns are a management technique used to suppress cogongrass and has an add-on benefit of reducing tick populations. However, climate change may threaten how frequently prescribed fires can be safely deployed. In my fourth chapter, I found that tick populations are most sensitive to leaf litter and humidity, which allows for management strategies as an alternative to prescribed burns.

Background: Pediatric minimally invasive surgery (MIS) is a standard technique worldwide. We aimed to analyze the research activity in this field. Methods: Articles on pediatric MIS (1991–2020) were analyzed from the Web of Science™ for the total number of publications, citations, journals, and impact factors (IF). Of these, the 50 most cited publications were evaluated in detail and classified according to the level of evidence (i.e., study design) and topic (i.e., surgical procedure). Results: In total, 4464 publications and 53,111 citations from 684 journals on pediatric MIS were identified. The 50 most cited papers were published from 32 institutions in the USA/Canada (n = 28), Europe (n = 19), and Asia (n = 3) in 12 journals. Four authors (USA/Europe) contributed to 26% of the 50 most cited papers as first/senior author. Hot topics were laparoscopic pyeloplasty (n = 9), inguinal hernia repair (n = 7), appendectomy, and pyloromyotomy (n = 4 each). The majority of publications were retrospective studies (n = 33) and case reports (n = 6) (IF 5.2 ± 3.2; impact index 16.5 ± 6.4; citations 125 ± 39.4). They were cited as often as articles with high evidence levels (meta-analyses, n = 2; randomized controlled trials, n = 7; prospective studies, n = 2) (IF 12.9 ± 22.5; impact index 14.0 ± 6.5; citations 125 ± 34.7; p > 0.05). Conclusions: Publications on laparoscopic pyeloplasty, inguinal hernia repair, appendectomy, and pyloromyotomy are cited most often in pediatric MIS. However, the relevant number of studies with strong evidence for the advantages of MIS in pediatric surgery is missing.

<p dir="ltr">In this era of changing global climate and globalization, the intricate relationships between non-native organisms and their impacts on forest health are of paramount concern. Bark and ambrosia beetles are diverse groups of insects that are among the most intercepted insects at international ports of entry. Once established, these insects can vector pathogens and disrupt functional forest dynamics. Bark and ambrosia beetles are known to attack various tree species, including black walnut (<i>Juglans nigra</i>), a valuable timer and nut-producing tree native to Eastern North America. Non-native woodboring beetles provide unique opportunities for ecological studies and pest management. This research investigates the chemical ecology and microbial dynamics in black walnut ecosystems to fill critical knowledge gaps and address the pressing issues surrounding forest health and sustainable management.</p><p dir="ltr">In Chapter 1, I review the current literature describing the use of semiochemicals in bark and ambrosia beetle management, non-native scolytines as vectors of phytopathogens, and the use of nematodes as natural antagonists of fungal pathogens in trees.</p><p dir="ltr">In Chapter 2, I aim to identify attractant and repellent semiochemicals for the ambrosia beetle <i>Anisandrus maiche</i>, which is a first step in developing effective management strategies for this species. I found that conophthorin and verbenone are strong repellents and that this beetle is attracted to ethanol in a dose-dependent manner.</p><p dir="ltr">In Chapter 3, I tested the hypothesis that <i>Anisandrus maiche </i>will be influenced by volatiles of its nutritional fungal symbiont, <i>Ambrosiella cleistominuta,</i> and that these compounds may synergize with ethanol. I identified seven unique compounds from the fungus and two fungal alcohols in the field. I found isobutyl alcohol to repel <i>A. maiche </i>while isoamyl alcohol has seasonal effects on <i>A. maiche </i>capture when paired with ethanol.</p><p dir="ltr">In Chapter 4, I aimed to characterize the assemblage of microorganisms residing on two non-native ambrosia beetles across diverse forest types. I tested the hypothesis that forest stand diversity and management regimes would affect the assemblage of microorganisms of ambrosia beetles. I found forest type influences the abundance of fungi and bacteria on <i>A. maiche </i>and <i>Xylosandrus crassiusculus</i> and that both beetle species transport genera of pathogenic fungi.</p><p dir="ltr">In Chapter 5, I test the hypothesis that inoculation with <i>Geosmithia morbida </i>alters the volatile profile of black walnut. I found one isolate of <i>G. morbida </i>induced changes in the volatile profile of black walnut bark and identified the compounds that changed relative to the control trees.</p><p dir="ltr">In Chapter 6, I tested the hypothesis that free-living fungivorous nematodes can modulate Thousand Cankers Disease severity. I found two genera of nematodes <i>Panagrolaimus </i>and <i>Aphelenchoides </i>to orient towards agents of the TCD system in Y-tube bioassays. <i>Aphelenchoides </i>sp. that were exposed to <i>G. morbida </i>grown on agar media augmented with black walnut bark extract significantly reduced <i>G. morbida </i>cankers in black walnut seedlings. This research has important implications for the management of TCD.</p><p dir="ltr">In Chapter 7, I summarize results from each of research chapter and discuss future research needs and directions to continue development of the knowledge surrounding chemical ecology and microbial dynamics of non-native scolytine beetles.</p>

Blood pressure (BP) monitoring is an important tool for management of hypertension, which is a significant risk for cardiovascular disease and premature death. Since cuff-based BP measurement can be uncomfortable and does not provide continuous readings, several cuffless methods that are typically based on within-beat information or on the pulse transit time (PTT) have recently been investigated. This work proposes a novel cuffless BP estimation approach that mainly uses the information from cardiovascular dynamics of photoplethysmogram (PPG) waveforms. This work is divided into three parts. The first part proposes a calibration-free approach that uses dynamic changes in the pulse waveform. Results from 200 patients showed that the method achieved grade B, in terms of accuracy, for diastolic blood pressure (DBP) based on the British Hypertension Society (BHS) standard and complied with the accuracy requirements of the Association for Advancement of Medical Instrumentation/European Society of Hypertension/International Organization for Standardization (AAMI/ESH/ISO) standard. The second part presents a method based on calibrated cardiovascular dynamics, achieved through a mathematical model that relates reflective PTT (R-PTT) to BP. Results from 30 patients showed a mean error (ME) of 0.58 mmHg, standard deviation of the error (SDE) of 8.13 mmHg, and a mean absolute error (MAE) of 4.93 mmHg for DBP and an ME of 2.52 mmHg, SDE of 12.28 mmHg, and an MAE of 8.82 mmHg for systolic blood pressure (SBP). The third part proposes a calibration-free method that combines morphology features and dynamic changes of the pulse waveform over short intervals. In this method a neural network was trained on 200 patients and tested on never-seen data from 25 other patients and provided an ME of -0.31 mmHg, SDE of 4.89 mmHg, and MAE of 3.32 mmHg for DBP and an ME of -4.02 mmHg, SDE of 10.40 mmHg, and MAE of 7.41 mmHg for SBP. Overall, the results show that cardiovascular dynamics may contribute useful information for cuffless estimation of BP.

京都大学 / 新制・論文博士 / 博士(農学) / 乙第13547号 / 論農博第2912号 / 新制||農||1101(附属図書館) / 学位論文||R5||N5428(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 大村 和香子, 教授 井鷺 裕司, 教授 今井 友也 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

Cerebral blood flow (CBF) is a biomarker for brain health, facilitating the advancement of studies on brain states in both healthy and diseased individuals. While there are indirect approaches of CBF based on human physiology, there is a need for technology that measures CBF directly and continuously. Laser speckle contrast imaging (LSCI) is an optical modality that measures changes in CBF by analyzing the blurring of speckle patterns. LSCI has been extensively employed to obtain two-dimensional blood flow maps in thinned-skull mouse brains and has found diverse applications in studies involving the retina, skin, and strokes. However, the effectiveness of LSCI has been limited in animal models due to the lack of depth-sensitivity. Speckle contrast optical spectroscopy (SCOS), an extension of LSCI for non-invasive human brain studies, has recently been developed to probe dynamics in deeper tissue regions by increasing the source-detector separation. But the low photon flux detected from human brain limits the usability of SCOS for brain activation measurements. To address these limitations, this thesis focuses on advancements made in laser speckle technology for improved measure of blood flow in both animal and human brains. Firstly, analytical and numerical methods have been developed for an interferometric LSCI system, which employs a heterodyne detection scheme to enhance CBF within the coherence volume in small animals. Next, a dynamic speckle model (DSM) is created to simulate the temporal evolution of the speckle patterns. DSM has been utilized to quantify the impact of noise sources on speckle contrast, particularly relevant in human brain measurements utilizing SCOS where low photon counts is a norm. Finally, a fiber-based SCOS system with a long source-detector separation has been presented to perform human brain activation studies. Through experiments involving three healthy subjects performing a mental subtraction task, changes in brain activation have been observed. Importantly, the SCOS system has demonstrated an order of magnitude improvement in the signal-to-noise ratio compared to the state-of-the-art diffuse correlation spectroscopy system.These methods serve as valuable tools to augment existing LSCI systems and promoting the widespread adoption of SCOS in human brain activation studies thus contributing to the development of future non-invasive, continuous, and cost-effective blood flow monitoring devices.

<p> Chameleon plant (<em>Houttuynia cordata</em> Thunb.) is native to Southern and Southeastern Asia. It can reproduce sexually through seeds and asexually through rhizomes and is invasive in multiple countries including the U.S. There has been much research on <em>H. cordata</em> as a medicinal species, and its potential as an invasive species is well documented. However, its herbicidal resistance has not previously been quantified. The objective of this study is to assess <em>H. cordata’s </em>resistance to herbicides. This study consisted of two rounds of tests to examine the resistance of <em>H. cordata</em> plants to three commonly used herbicides: SpeedZone, Weed-B-Gon, and Roundup. Two concentrations of each herbicide were used during each trial in the study: the recommended concentration and twice the recommended concentration. Herbicide treatments were applied outside the greenhouse. Herbicides were sprayed uniformly on the plants until the herbicide was dripping off the leaves. The growth of the treated plants was then monitored in the greenhouse. The herbicides generally reduced growth of the plants temporarily. However, plant extermination was not achieved. Plant samples from all herbicidal treatments regrew from rhizomes after all herbicide treatments. Results from the study showed that <em>H. cordata </em>could not be controlled by the recommended concentrations of herbicides commercially available for horticultural uses in the U.S. Doubling the recommended herbicide concentration was also ineffective in exterminating <em>H. cordata </em>plants. This research clearly showed that <em>H. cordata</em> has the potential to become a highly invasive species with the potential to negatively affect the ecological integrity of many communities in the U.S.</p>