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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

The Effect of Serum BDNF Levels on Central Serotonin Transporter Availability in Obese Versus Non-Obese Adults: A [11C]DASB Positron Emission Tomography Study

Hinderberger, Philipp 29 November 2016 (has links) (PDF)
Background: Serotonin (5-HT) and its neurotrophic support system, specifically brain-derived neurotrophic factor (BDNF), are thought to modulate energy homeostasis and susceptibility to obesity. Moreover, a polymorphism (5-HTTLPR) in the serotonin reuptake transporter (5-HTT) gene impairs its transcription, thereby altering serotonergic tone and potentially contributing to such susceptibility. This study aims to investigate the effect of BDNF, biallelic 5-HTTLPR, and central in-vivo 5-HTT availability in highly obese versus non-obese subjects using positron emission tomography (PET) and 5-HTT selective [11C]DASB. Methods: Thirty-eight subjects, 24 obese (body mass index, BMI, >35 kg/m2), otherwise mentally and physically healthy, and 14 non-obese (BMI ≤ 25 kg/m2), age- and sex-matched healthy controls were included in this study. Parametric images of binding potential were generated from PET data. Central 5-HTT availability, 5-HTTLPR genotype, and serum BDNF concentrations were analyzed, first in a volume of interest, then in a voxel-wise manner. Results: Overall, our results showed an absence of a linear correlation between BDNF, in-vivo central 5-HTT availability, and body mass index (BMI). 5-HTTLPR genotyping revealed BDNF and hippocampal 5-HTT availability to be negatively correlated (r = −0.57, p = 0.007) in long allelic homozygotes. However, obese subjects exhibited opposing effects of BDNF levels on 5-HTT availability in the nucleus accumbens (NAcc) relative to our non-obese controls. Conclusions: Our data did not confirm an overall correlation between serum BDNF, in-vivo central 5-HTT availability, 5-HTTLPR, and BMI. However, there is evidence that serotonergic tone linked to BDNF, specifically in the NAcc, is involved in the pathophysiology of obesity, although this needs further exploration over a wide range of reward-related eating behaviors.
32

Personality Characteristics Associated with Pet Ownership: Validating the Theoretical Propositions of Boris Levinson

Esparza, Jana Scoville 08 1900 (has links)
The purpose of the present study was to provide validation for Levinson's theory about pets and human personality development. Levinson (1978) proposed that the personality development of individuals who have pets to which they are attached differs from that of those who do not have pets and that pets play an important role in facilitating the development of certain adaptive personality traits. In the present study, specific areas that were addressed included differences in certain personality characteristics between life-long pet owners who were strongly attached to their pets, life-long pet owners who were less strongly attached to their pets, and people who had owned pets for only a limited period of time in their lives. One hundred undergraduates completed the Pet Attitude Scale, the Tennessee Self Concept Scale, the Personality Research Form - Form E, the Hogan Empathy Scale, the Fundamental Interpersonal Relations Orientation - Behavior (FIRO-B), and the IPAT Anxiety Scale Questionnaire. No significant differences were found between the three pet owner groups in levels of affiliation with other people, impulse control, nurturance, succorance, capacity for empathy, and anxiety levels. In addition, no significant differences were found between the three pet owner groups in interpersonal behavior characteristics or self-esteem. Concurrent validity was shown between membership in the different pet owner groups and positive attitudes toward pets as measured by the Pet Attitude Scale. As predicted, the most attached life-long pet owners reported more positive attitudes toward pets than the least attached life-long pet owners or the limited-time pet owners.
33

Otimização do sistema de carga e descarga no porta-alvo de irradiação  de H218O utilizando a produção de 18F- no Cíclotron Cyclone 30 do IPEN-CNEN/SP / LOAD AND UNLOAD SYSTEM OPTIMIZATION ON H2 18O IRRADIATION TARGET USED FOR 18F- PRODUCTION AT THE CYCLOTRON CYCLONE 30 FROM IPEN-CNEN/SP

Costa, Osvaldo Luiz da 04 February 2009 (has links)
O aumento da demanda no Brasil pelo radiofármaco [18F]FDG para exames de tomografia por emissão de pósitron (PET-CT) e sua meia-vida de 109,7 minutos exigem uma atenção especial para a cadeia produtiva deste radiofármaco. Desde a irradiação da água enriquecida em 18O até a passagem do paciente pelo tomógrafo, numa seqüência de procedimentos que pode durar até cerca de seis horas, todas as etapas da cadeia produtiva devem ter a maior confiabilidade possível, pois qualquer falha em uma das etapas será sentida na extremidade da cadeia produtiva. A falta de indicação de posição da válvula do Sistema de Carga e Descarga do Porta-alvo de 18F- no Centro de Aceleradores Cíclotron levou a perda de produção de 18F-, contaminação da Sala de Irradiação e aumento da dose dos trabalhadores envolvidos na operação e manutenção dos sistemas de irradiação. Este trabalho testou o comportamento de três tipos de sensores de posição (microswitch, reedswitch e sensor de proximidade indutivo) no ambiente da Sala de Irradiação 1.2 do Centro de Aceleradores Cíclotron, que está sujeito a altas taxas de radiação gama e nêutrons devido à produção rotineira de 18F- e 123I, através deste teste foi possível encontrar o sensor de posição mais adequado para trabalhar no porta-alvo de 18F-, e através da reprogramação do controlador lógico programável, foi possível evitar este tipo de falha durante a produção de 18F- no Centro de Aceleradores Cíclotron, e aumentar a confiabilidade na cadeia produtiva do [18F]FDG. / The demand growing in Brazil by the radiopharmaceutical [18F]FDG in positron emission tomography (PET-CT) and the 109,7 minutes half life claim special attention to the productive chain of this radiopharmaceutical. Since the [18O]water irradiation until the tomograph patient scanning, in sequential procedures that may spent about six hours, all the productive chain stages must be as reliable as possible, because any stage failed will be perceived in productive chain extremity. The position indication absence from Load and Unload 18F- Target System valve in Cyclotron Accelerators Center resulted in 18F- production loss, Irradiation Room contamination and the increase workers dose responsible by operation and maintenance of irradiation systems. This study tested the behaviour of three types of position sensors (microswitch, reedswitch and inductive sensor), into Irradiation Room 1.2 environment of the Cyclotron Accelerators Center, where there are high gamma radiation and neutrons rates because the routine 18F- and 123I production, through this test was possible to discover the fitter position sensor to run on 18F- Target, and after rewriting the programmable logic controller software was possible avoid this type of fail at 18F- production time in Cyclotron Accelerators Center, and to grow up the reliability on [18F]FDG productive chain.
34

Otimização do sistema de carga e descarga no porta-alvo de irradiação  de H218O utilizando a produção de 18F- no Cíclotron Cyclone 30 do IPEN-CNEN/SP / LOAD AND UNLOAD SYSTEM OPTIMIZATION ON H2 18O IRRADIATION TARGET USED FOR 18F- PRODUCTION AT THE CYCLOTRON CYCLONE 30 FROM IPEN-CNEN/SP

Osvaldo Luiz da Costa 04 February 2009 (has links)
O aumento da demanda no Brasil pelo radiofármaco [18F]FDG para exames de tomografia por emissão de pósitron (PET-CT) e sua meia-vida de 109,7 minutos exigem uma atenção especial para a cadeia produtiva deste radiofármaco. Desde a irradiação da água enriquecida em 18O até a passagem do paciente pelo tomógrafo, numa seqüência de procedimentos que pode durar até cerca de seis horas, todas as etapas da cadeia produtiva devem ter a maior confiabilidade possível, pois qualquer falha em uma das etapas será sentida na extremidade da cadeia produtiva. A falta de indicação de posição da válvula do Sistema de Carga e Descarga do Porta-alvo de 18F- no Centro de Aceleradores Cíclotron levou a perda de produção de 18F-, contaminação da Sala de Irradiação e aumento da dose dos trabalhadores envolvidos na operação e manutenção dos sistemas de irradiação. Este trabalho testou o comportamento de três tipos de sensores de posição (microswitch, reedswitch e sensor de proximidade indutivo) no ambiente da Sala de Irradiação 1.2 do Centro de Aceleradores Cíclotron, que está sujeito a altas taxas de radiação gama e nêutrons devido à produção rotineira de 18F- e 123I, através deste teste foi possível encontrar o sensor de posição mais adequado para trabalhar no porta-alvo de 18F-, e através da reprogramação do controlador lógico programável, foi possível evitar este tipo de falha durante a produção de 18F- no Centro de Aceleradores Cíclotron, e aumentar a confiabilidade na cadeia produtiva do [18F]FDG. / The demand growing in Brazil by the radiopharmaceutical [18F]FDG in positron emission tomography (PET-CT) and the 109,7 minutes half life claim special attention to the productive chain of this radiopharmaceutical. Since the [18O]water irradiation until the tomograph patient scanning, in sequential procedures that may spent about six hours, all the productive chain stages must be as reliable as possible, because any stage failed will be perceived in productive chain extremity. The position indication absence from Load and Unload 18F- Target System valve in Cyclotron Accelerators Center resulted in 18F- production loss, Irradiation Room contamination and the increase workers dose responsible by operation and maintenance of irradiation systems. This study tested the behaviour of three types of position sensors (microswitch, reedswitch and inductive sensor), into Irradiation Room 1.2 environment of the Cyclotron Accelerators Center, where there are high gamma radiation and neutrons rates because the routine 18F- and 123I production, through this test was possible to discover the fitter position sensor to run on 18F- Target, and after rewriting the programmable logic controller software was possible avoid this type of fail at 18F- production time in Cyclotron Accelerators Center, and to grow up the reliability on [18F]FDG productive chain.
35

Value of using liver FDG uptake as background activity in standardizing FDG PET/CT studies

Wilson, Colin Michael January 2011 (has links)
Thesis (M.A.)--Boston University / The standardized uptake value (SUV) is increasingly being used for diagnosis, staging, and monitoring disease in clinical oncology. Comparing tumor SUV to background SUV is an attractive way to minimize variability and ensure the quality of scans across different institutions. The liver has been identified as a potential source for background normalization, however no studies have compared the liver to other background sites for a variety of cancers. The purpose of this study was to evaluate the use of liver uptake for the standardization of FDG PET/CT imaging. Scans from 145 patients were prospectively reviewed under the supervision of a radiologist with board certification in nuclear medicine (R.M.S. , 3 years of experience). Liver SUV values were correlated to mediastinum SUV values in lung and breast cancer patients, and internal jugular vein (IJV) SUV values in head and neck cancer patients. The independent t-test was used to determine if there was a statistically significant affect of the amount of incubation time or use of intravenous contrast on the SUV. For the lung and breast cancer patients, a strong correlation was observed between the mediastinum SUVmean and liver SUVmean (r = 0.89), whereas for the head and neck cancer patients, a weaker correlation was observed between the IJV SUVmean and the liver SUVmean (r = 0.69). Neither the amount of incubation time nor the use of IV contrast demonstrated a significant affect on the SUV. We conclude that liver SUVmean may be used to standardize FOG PET/CT studies in cancers of the lung, breast and head and neck. However, additional studies in other cancers as well as the affects of age, gender, benign disease and use of chemotherapy are still desired before widespread adoption of this standard.
36

Survivors' Experiences of Pet Abuse Within the Cycle of Domestic Violence

Johnson, Taylor Chastain 01 January 2018 (has links)
Domestic violence is a pervasive issue that impacts all members of a household, including pets. There is comprehensive quantitative evidence to suggest that domestic violence and pet abuse commonly co-occur; however, as the personal accounts of pet-owning survivors have started to emerge through qualitative investigation, more research is needed to understand the unique experiences of pet abuse that take place alongside instances of domestic violence. This phenomenological investigation utilized control balance theory and a feminist framework to uncover the experiences of survivors who entered their pets into an animal care program specifically designed to help during times of domestic violence escape. Data from interviews with 12 participants were compared to secondary qualitative data from anonymous animal abuse surveys at the community partner organization. A lens of interpretative phenomenological analysis was used to identify global themes related to survivors' experiences of pet ownership while escaping domestic violence. From these testimonies, pets were revealed to be important to consider in responding to domestic violence because pets not only played key roles of emotional support in the survivors' lives, but they were also threatened and harmed by abusers to control victims. Furthermore, the provision of pet care for survivors who were escaping domestic violence was determined to be a meaningful intervention. Through learning of the experiences of pet ownership along the trajectory of recovery for domestic violence survivors, advocates may be better prepared to serve clients at this intersection. Furthermore, the empirical understanding of the role of the human-animal bond in domestic violence survivorship was augmented by this study.
37

The low birth rate driven by the pet market Opportunities and coping strategies

Wu, Ya-lin 10 February 2012 (has links)
The low birth rate is a global trend Taiwan has entered the low birth rate society! The low birth rate have a deep impact not only on individuals, families, society, nation, or even a whole industry. According to the Ministry of the Interior (2010) data show that the total fertility rate of women in our country from 1960 to 1965 of 4.825, down to 0.895 in 2000-2010, fertility rates highest in the world of the reciprocal of the first, even more than the aging neighbor country Japan is even lower. Estimated to 105 years of the Republic of Taiwan's population will probably enter "zero growth"! Today's changing social structures, not married and no children of the proportion continues to increase, the motives of the pet is not just for economic or practical purposes, but accompanied by the emotional pets and owners to produce a interdependent relationship. Their beloved pet is willing to increase spending, thus creating a huge consumer market. Expected in the future, the fertility rate continued low standard of people keeping pets will be more market demand for more vigorous, it is bound to create more pet business opportunities. The purpose of this study is to investigate the low birth rate to bring the pet business opportunities, "the case of its competitors, strengths and weaknesses and its opportunities and threats SWOT analysis to understand the circumstances of its comparative advantage. Furthermore, the use of the SWOT matrix analysis graph matching, correlation analysis of the pet industry, summed up the advantages and disadvantages of the pet industry, combined with the related policy analysis theory. Finally, conclusions and provide recommendations in the strategy of the industry. This study eventually granted to the following six factors suggested that the industry reference in the business: (¤@) management style (¤G) market segment (¤T) education and training (¥|) strategic alliance (¤­) Promotion (¤») pet related systems and laws Keywords: low birth rate, fertility, pet, business opportunities, the SWOT, the pet industry
38

DFM (Design for Manufacturability) metodo taikymas gaminiams iš plastiko gaminti / DFM (Design For Manufacturability) methodology application to the part,made from plastic

Tamošauskas, Aurimas 29 September 2008 (has links)
Šis ištirtas DFM metodas padeda atkreipti projektuotojų dėmesį į tas presuojamojo liejimo formavimo ypatybes, kurios yra linkusios didinti gaminio apdirbimo sąnaudas. Tyrime naudojame „šešių laipsnių koduojančia sistema“ tam, kad nustatyti galutines preliminarias ruošinio apdirbimo sąnaudas. Čia pabrėžiamos tos ypatybes, kurios žymiai didina kainą, kad projektuotojai galėtų sumažinti gaminamos detalės sudėtingumą. Naudojant pristatytą metodologiją, projektuotojai gali įvykdyti ruošinių apdirbimo sąnaudų įvertinimą ankstyvojoje konstravimo stadijoje. Tai gali būti įvikdyta pasitelkiant jų apytiksle vieta ir orientacija. Išsamūs matmenys nėra būtini. Metodologija parodo tai, ką detalių charakteristikos įtakoja kainai, kad pagerintų perkonstruotą detalę. / The master’s thesis present the rewiew of design manufacture method. Mechanical part design plays an important role whether company will succeed in market or will fail. From my point of view there are three main measures of the DFM (Design For Manufacture) process: cost, quality and time, which are pivotal in design process. Regardless of the product being designed – whether it is an entire system or some small subpart of a larger product - the customer and management always want it cheaper, better and faster. In this project has described a systematic approach for calling designers attention to those features of injection molding that tend to increase the tooling cost to manufacture parts – and for estimating the relative costs of tooling. The system employs a six – digit coding system for determining total relative tooling cost, which groups parts according to their similarity in tool construction difficulty. The system highlight those features that significantly increase cost so that designers can minimize difficult – to – produce features.
39

A Mini-PET beamline for optimized proton delivery to the ISOTRACE™ target system

Dehnel, M. P., Jackle, P., Potkins, D., Stewart, T., Boudreault, G., Jones, T., Philpott, C. 19 May 2015 (has links) (PDF)
Introduction The ISOTRACE™ Super-Conducting Cyclotron is PMB-Alcen’s redeveloped and modernized version of Oxford Instrument’s OSCAR superconducting cyclotron [1]. Its extracted 80+ mi-croamperes of 12 MeV protons are used for the production of PET radioisotopes. Following the philosophy of Dickie, Stevenson, Szlavik [2] for minimizing dose to personnel, and as developed by Dehnel et al [3,4], and Stokely et al [5], the ISOTRACE™ shall utilize an innovative, light-weight, integrated and self-supporting Mini-Beamline. This permits the relatively high residual radiation fields around PET targets to be moved ~1 metre away from the cyclotron, and facilitates the use of local shielding (around the targets) that limits prompt gammas and neutrons, but more importantly attenuates the residual target radiation, so that maintenance/research staff can work on the cyclotron in a relatively low activity environment. In addition, the mini-beamline for PET utilizes a compound quadrupole/steerer doublet that permits active and dynamic focusing/steering of the extracted proton beam for optimized production and minimized losses [3], so it improves on the successful work of Theroux et al [6]. The integrated beamline unit is extremely small, so that it is very unlike bulky traditional PET and SPECT beamlines that require substantial support structures, such as described by Dehnel in [7,8]. Material and Methods The ISOTRACE™ cyclotron is pictured in FIG. 1. The exit port flange and gate valve to which the integrated mini-beamline for PET shall be mounted is shown. Immediately upstream of the exit port, hidden from view, is a 4 jaw collimator (called BPI for Beam Position Indicator) with spilled beam current readbacks to the control system. TABLE 1 shows the nominal beam emittance and Twiss parameter values at the exit port flange location. This ion-optical information is necessary to simulate ion beam transport, develop the mini-beamline, and determine a nominal tune (i.e. magnet settings). Results and Conclusion TABLE 2 shows the ion-optical system parameters. FIGS. 2 and 3 show the horizontal and vertical beam profiles. The Horizontally focusing Quadrupole magnet (HQ), and Vertically focusing Quadrupole magnet (VQ) aperture diameter, 33 mm, was chosen to give sufficient beam acceptance. The focusing strength is a function of BL, so the effective length, L = 150 mm, was chosen to ensure Bmax less than 0.3 Tesla, while keeping overall magnet mass down. The quad-rupole magnets are fitted with water-cooled compound coils in which the copper/mylar strip wound portion of each coil is a winding for the quadrupole focusing function, and the wire wound portion is for the steering function. To increase beam acceptance and provide additional section strength for the pipe support function, the internal aperture of the low-activation aluminium beam pipe and the external shape are in the shape of a cross. FIG. 4 shows the beam crosssection at the mid-point of the downstream quadrupole magnet, and illustrates the additional acceptance as compared to a round beampipe. In order to machine the interior profile, the pipe is comprised of two premachined pieces that are friction stirwelded together. FIG. 5 is an isometric of the mini-beamline for PET. The four upstream HQ compound coils are excited with a 75A power supply for the horizontally focusing quadrupole magnet function, and a ± 10A power supply for a vertical steering function. The same power supplies are used for the four downstream VQ compound coils for the purpose of a vertically focusing quadrupole magnet function and horizontal steering function.
40

Cyclotron Production and PET/MR Imaging of 52Mn

Wooten, A. L., Lewis, B. C., Laforest, R., Smith, S. V., Lapi, S. E. 19 May 2015 (has links) (PDF)
Introduction The goal of this work is to advance the production and use of 52Mn (t½ = 5.6 d, β+: 242 keV, 29.6%) as a radioisotope for in vivo preclinical nuclear imaging. More specifically, the aims of this study were: (1) to measure the excitation function for the natCr(p,n)52Mn reaction at low energies to verify past results [1–4]; (2) to measure binding constants of Mn(II) to aid the design of a method for isolation of Mn from an irradiated Cr target via ion-exchange chromatography, building upon previously published methods [1,2,5–7]; and (3) to perform phantom imaging by positron emission tomography/magnetic resonance (PET/MR) imaging with 52Mn and non-radioactive Mn(II), since Mn has potential dual-modality benefits that are beginning to be investigated [8]. Material and Methods Thin foils of Cr metal are not available commercially, so we fabricated these in a manner similar to that reported by Tanaka and Furukawa [9]. natCr was electroplated onto Cu discs in an industrial-scale electroplating bath, and then the Cu backing was digested by nitric acid (HNO3). The remaining thin Cr discs (~1 cm diameter) were weighed to determine their thickness (~ 75–85 μm) and arranged into stacked foil targets, along with ~25 μm thick Cu monitor foils. These targets were bombarded with ~15 MeV protons for 1–2 min at ~1–2 μA from a CS-15 cyclotron (The Cyclotron Corporation, Berkeley, CA, USA). The beamline was perpendicular to the foils, which were held in a machined 6061-T6 aluminum alloy target holder. The target holder was mounted in a solid target station with front cooling by a jet of He gas and rear cooling by circulating chilled water (T ≈ 2–5 °C). Following bombardment, these targets were disassembled and the radioisotope products in each foil were counted using a high-purity Ge (HPGe) detector. Cross-sections were calculated for the natCr(p,n)52Mn reaction. Binding constants of Mn(II) were measured by incubating 54Mn(II) (t½ = 312 d) dichloride with anion- or cation-exchange resin (AG 1-X8 (Cl− form) or AG 50W-X8 (H+ form), respectively; both: 200–400 mesh; Bio-Rad, Hercules, CA) in hydrochloric acid (HCl) ranging from 10 mM-8 M (anion-exchange) and from 1 mM-1 M (cation-exchange) or in sulfuric acid (H2SO4) ranging from 10 mM-8 M on cation-exchange resin only. The amount of unbound 54Mn(II) was measured using a gamma counter, and binding constants (KD) were calculated for the various concentrations on both types of ion-exchange resin. We have used the unseparated product for preliminary PET and PET/MR imaging. natCr metal was bombarded and then digested in HCl, resulting in a solution of Cr(III)Cl3 and 52Mn(II)Cl2. This solution was diluted and imaged in a glass scintillation vial using a microPET (Siemens, Munich, Germany) small animal PET scanner. The signal was corrected for abundant cascade gamma-radiation from 52Mn that could cause random false coincidence events to be detected, and then the image was reconstructed by filtered back-projection. Additionally, we have used the digested target to spike non-radioactive Mn(II)Cl2 solutions for simultaneous PET/MR phantom imaging using a Biograph mMR (Siemens) clinical scanner. The phantom consisted of a 4×4 matrix of 15 mL conical tubes containing 10 mL each of 0, 0.5, 1.0, and 2.0 mM concentrations of non-radioactive Mn(II)Cl2 with 0, 7, 14, and 27 μCi (at start of PET acquisition) of 52Mn(II)Cl2 from the digested target added. The concentrations were based on previous MR studies that measured spin-lattice relaxation time (T1) versus concentration of Mn(II), and the activities were based on calculations for predicted count rate in the scanner. The PET/MR imaging consisted of a series of two-dimensional inversion-recovery turbo spin echo (2D-IR-TSE) MR sequences (TE = 12 ms; TR = 3,000 ms) with a wide range of inversion times (TI) from 23–2,930 ms with real-component acquisition, as well as a 30 min. list-mode PET acquisition that was reconstructed as one static frame by 3-D ordered subset expectation maximization (3D-OSEM). Attenuation correction was performed based on a two-point Dixon (2PD) MR sequence. The DICOM image files were loaded, co-registered, and windowed using the Inveon Research Workplace software (Siemens).

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