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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.
1

Analysis of three close eclipsing binary systems: BP Velorum, V392 Carinae and V752 Centauri

Schumacher, Hana Josephine January 2008 (has links)
This thesis reports photometric and spectroscopic studies of three close binary systems; BP Velorum, V392 Carinae and V752 Centauri. BP Velorum, a W UMa-type binary, was observed photometrically in February 2007. The light curves in four filters were fitted simultaneously with a model generated in the eclipsing binary modeling software package PHOEBE. The best model was one with a cool star spot on the secondary larger component. The light curves showed additional cycle-to-cycle variations near the times of maximum light which may indicate the presence of star spots that vary in strength and/or location on a time scale comparable with the orbital period, (P = 0.265 d). The system was confirmed to belong to the W-type subgroup of W UMa binaries for which the deeper primary minimum is due to an occultation. V392 Carinae, a detached binary with an orbital period of 3.147 d, was observed photometrically by Michael Snowden in 1997. These observations were reduced and combined with the published light curve from Debernardi and North (2001). High resolution spectroscopic images were taken using the University of Canterbury's HERCULES spectrograph. The radial velocities measured from these observations were combined with velocities from Debernardi and North (2001). The radial velocity and light curves were fit simultaneously, confirming that V392 Car is a detached system of two main sequence A stars with a mass-ratio of 0.95. The derived systematic velocity is consistent with V392 Car being a member of the open cluster NGC 2516. The W UMa-type binary V752 Centauri was observed photometrically and spectroscopically during 2007. The high resolution spectra displayed weak sharp lined features superimposed over the strong broad lined spectrum expected from the 0.370 d contact binary. Fourier methods were used to separate the broad and sharp spectral features and radial velocities for each were measured by cross-correlation. A fit to the photometry and radial velocities for the contact binary implied a system of two late F stars with a mass-ratio of 3.38 in an over-contact configuration. The derived systematic velocity (−13.8km/s), has changed significantly from the 1972 value (29.2km/s). The third (sharp lined) component's radial velocities were measured and found to have a period of 5.147 d, semi-amplitude of 43.4km/s and systematic velocity of −7.3km/s. The likely configuration of the entire system is that of a contact binary in a long period orbit about a lower mass detached binary. V752 Cen is thus a triple lined spectroscopic quadruple.
2

Analysis of three close eclipsing binary systems: BP Velorum, V392 Carinae and V752 Centauri

Schumacher, Hana Josephine January 2008 (has links)
This thesis reports photometric and spectroscopic studies of three close binary systems; BP Velorum, V392 Carinae and V752 Centauri. BP Velorum, a W UMa-type binary, was observed photometrically in February 2007. The light curves in four filters were fitted simultaneously with a model generated in the eclipsing binary modeling software package PHOEBE. The best model was one with a cool star spot on the secondary larger component. The light curves showed additional cycle-to-cycle variations near the times of maximum light which may indicate the presence of star spots that vary in strength and/or location on a time scale comparable with the orbital period, (P = 0.265 d). The system was confirmed to belong to the W-type subgroup of W UMa binaries for which the deeper primary minimum is due to an occultation. V392 Carinae, a detached binary with an orbital period of 3.147 d, was observed photometrically by Michael Snowden in 1997. These observations were reduced and combined with the published light curve from Debernardi and North (2001). High resolution spectroscopic images were taken using the University of Canterbury's HERCULES spectrograph. The radial velocities measured from these observations were combined with velocities from Debernardi and North (2001). The radial velocity and light curves were fit simultaneously, confirming that V392 Car is a detached system of two main sequence A stars with a mass-ratio of 0.95. The derived systematic velocity is consistent with V392 Car being a member of the open cluster NGC 2516. The W UMa-type binary V752 Centauri was observed photometrically and spectroscopically during 2007. The high resolution spectra displayed weak sharp lined features superimposed over the strong broad lined spectrum expected from the 0.370 d contact binary. Fourier methods were used to separate the broad and sharp spectral features and radial velocities for each were measured by cross-correlation. A fit to the photometry and radial velocities for the contact binary implied a system of two late F stars with a mass-ratio of 3.38 in an over-contact configuration. The derived systematic velocity (−13.8km/s), has changed significantly from the 1972 value (29.2km/s). The third (sharp lined) component's radial velocities were measured and found to have a period of 5.147 d, semi-amplitude of 43.4km/s and systematic velocity of −7.3km/s. The likely configuration of the entire system is that of a contact binary in a long period orbit about a lower mass detached binary. V752 Cen is thus a triple lined spectroscopic quadruple.
3

No Significant Difference in Clinically Relevant Findings Between Pillcam SB3 and Pillcam SB2 Capsules in a United States Veteran Population

Aasen, Tyler D., Wilhoite, David, Rahman, Aynur, Devani, Kalpit, Young, Mark, Swenson, James 16 February 2019 (has links)
BACKGROUND: Capsule endoscopy (CE) allows for a non-invasive small bowel evaluation for a wide range of gastrointestinal (GI) symptoms and diseases. Capsule technology has been rapidly advancing over recent years, often improving image frequency and quality. The Pillcam SB3 (SB3) capsule is one such technology that offers an adaptive frame rate advantage over the previous versions of the capsule the Pillcam SB2 (SB2). Some have proposed that this improvement in capsule technology may lead to increased diagnostic yields; however, real world clinical data is currently lacking. AIM: To evaluate the clinically relevant findings of SB3 and SB2 capsules in a population of United States veterans. METHODS: A retrospective analysis of 260 consecutive CE studies was performed including 130 SB3 and 130 SB2 capsule studies. Recorded variables included: age, gender, type of capsule, body mass index, exam completion, inpatient status, opioid use, diabetes, quality of preparation, gastric transit time, small bowel transit time, indication, finding, and if the exam resulted in a change in clinical management. The primary outcome measured was the detection of clinically relevant findings between SB3 and SB2 capsules. RESULTS: Mean age of the study population was 67.1 ± 10.4 years and 94.2% of patients were male. Of these 28.1% were on opioid users. The most common indications for capsule procedure were occult GI bleeding (74.6%) and overt GI bleeding (14.6%). Rates of incomplete exam were similar between SB3 and SB2 groups (16.9% 9.2%, = 0.066). The overall rate of clinically relevant finding was 48.9% in our study. No significant difference was observed in SB3 SB2 capsules for clinically relevant findings (46.2% 51.5%, = 0.385) or change in clinical management (40.8% 50.0%, = 0.135). CONCLUSION: Our study found no significant difference in clinically relevant findings between SB3 and SB2 capsules.
4

Persistent Oral Dyskinesias Induced by Long-term Haloperidol Treatment is Dissociated from Changes in Neostriatal B(max) and Mrna Content for Dopamine D(2) Receptors

Huang, Nuoyu 01 May 1995 (has links)
Due to the presumed associations of dopamine (DA) receptor supersensitivity phenomena in both long-term neuroleptic-treated tardive dyskinetic rats and neonatal 6-hydroxydopamine (n6-OHDA)-lesioned rats, we studied the influence of haloperidol on n6-OHDA-lesioned rats. At 3 days after birth rats received 6-OHDA-HBr (200 $\mu$g, bilateral intracerebroventricularly; desipramine pretreatment, 20 mg/kg, 1h) or vehicle. Two months later haloperidol (1.5/kg/day $\times$ 2 days/week for 4 weeks, then 1.5 mg/kg/day, every day for 10 months) was added to the drinking water. Spontaneous oral activity of intact and n6-OHDA-lesioned rats receiving haloperidol was reached and maintained at significantly higher levels after 15 weeks of haloperidol treatment. Haloperidol treatment produced greater oral activity in n6-OHDA-lesioned rats as compared to intact rats. At 11 months there were 35.8 $\pm$ 4.9 vs. 18.4 $\pm$ 2.1 oral movements in lesioned vs. intact rats receiving haloperidol. This high level of spontaneous oral activity was not attenuated by scopolamine and persisted in the lesioned rats for at least 8 months after haloperidol withdrawal. Reverse transcription polymerase chain reaction (RT-PCR) analysis of alternatively-spliced isoforms of DA D$\sb2$ (D$\sb{\rm 2S}$ and D$\sb{\rm 2L}$) receptors showed that D$\sb{\rm 2L}$ receptor mRNA levels of intact and n6-OHDA-lesioned rats receiving haloperidol were significantly elevated after 11 months of treatment and returned to normal level 8 months after haloperidol withdrawal. Similarly, the B$\sb{\rm max}$ for $\rm\lbrack\sp3 H\rbrack$raclopride binding to striatal homogenates was significantly increased in intact and nG-OHDA lesioned rats receiving chronic haloperidol. The B$\sb{\rm max}$ was at the control level after 8 months of haloperidol cessation. D$\sb{\rm 2L}$ and 5-HT$\sb{\rm 2C}$ receptor mRNA levels were not altered by chronic haloperidol treatment. The effects of assorted receptor-specific drugs on oral activity were tested in our rats to study possible mechanisms underlying the regulation of oral activity. The findings of this study demonstrate that alterations at mRNA and receptor levels of DA D$\sb2$ receptors are not critical for maintaining persisting enhanced oral dyskinesias after long-term haloperidol treatment. The long-lasting stable high frequency of oral dyskinesias after haloperidol withdrawal in these rats provides a means for testing agents that have the potential to attenuate dyskinetic oral activity.

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