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- Title
- Youth Labor Market Conditions and the NEET Population in the EU: Do Poor Labor Market Opportunities Discourage Youth?.
- Creator
-
Hudson, Jennifer, Hamann, Kerstin, Kinsey, Barbara, Powell, Jonathan, University of Central Florida
- Abstract / Description
-
This study examines how poor labor market opportunities discourage youth between the ages of 15 and 24 and 15 to 29 from participating in the labor market in the European Union between 2005 and 2013. A critical portion of inactive NEETs (youth not in employment, education, or training) reports to be discouraged due to a recognized (")lack of opportunities in the labor market.(") Despite indications from descriptive analyses that the conditions that drive the distinct subsets of the NEET...
Show moreThis study examines how poor labor market opportunities discourage youth between the ages of 15 and 24 and 15 to 29 from participating in the labor market in the European Union between 2005 and 2013. A critical portion of inactive NEETs (youth not in employment, education, or training) reports to be discouraged due to a recognized (")lack of opportunities in the labor market.(") Despite indications from descriptive analyses that the conditions that drive the distinct subsets of the NEET population vary, empirical examinations of the effects of these conditions on the rates of different NEET groups across countries and over time are lacking. The policies prescribed for the NEET group as a whole tend to ignore the special needs of discouraged, inactive NEETs. Beyond the fundamental problem of engaging these individuals in the labor market, neglecting this group has a variety of implications, ranging from social exclusion, to poverty, and even radicalism. A central goal of this project is to determine what a recognized (")lack of opportunities(") means. What is known concretely is that fellow youth are increasingly vulnerable to a range of labor market outcomes and conditions beyond unemployment, including difficulty transitioning into the labor market (school-to-work transitions), in-work poverty risk, non-standard employment opportunities (involuntary and voluntary), limited ability to transition into secure employment (i.e. upward mobility), lower wage levels, atypical employment, limited job security and support, and long-term unemployment. Utilizing aggregated survey data from the EU Labor Force Survey and EU Survey on Income and Living Conditions, I examine how a range of labor market outcomes and conditions for youth, representative of the poor labor market opportunities, affect the frequency of discouraged NEETs across 24 EU countries between 2005 and 2013. Findings suggest that the incidence of involuntary non-standard work, in-work poverty risk, and atypical employment among fellow youth and the incidence of decreased work security among the adult working age population are associated with an increase in discouraged, inactive NEETs. This suggests that engaging this hard to reach subgroup of the NEET population requires a greater emphasis on creating improved labor market opportunities.
Show less - Date Issued
- 2017
- Identifier
- CFE0006605, ucf:51292
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006605
- Title
- Youth marches toward socialism: Report made Sept. 26, 1935, to the Sixth World Congress of the Young Communist International.
- Creator
-
Michal,Wolf, Young Communist International
- Date Issued
- 1936
- Identifier
- 369335, CFDT369335, ucf:5418
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/369335
- Title
- Ytterbium-doped fiber-seeded thin-disk master oscillator power amplifier laser system.
- Creator
-
Willis-Ott, Christina, Richardson, Martin, Schulzgen, Axel, Delfyett, Peter, Chow, Louis, University of Central Florida
- Abstract / Description
-
Lasers which operate at both high average power and energy are in demand for a wide range of applications such as materials processing, directed energy and EUV generation. Presented in this dissertation is a high-power 1 ?m ytterbium-based hybrid laser system with temporally tailored pulse shaping capability and up to 62 mJ pulses, with the expectation the system can scale to higher pulse energies. This hybrid system consists of a low power fiber seed and pre-amplifier, and a solid state thin...
Show moreLasers which operate at both high average power and energy are in demand for a wide range of applications such as materials processing, directed energy and EUV generation. Presented in this dissertation is a high-power 1 ?m ytterbium-based hybrid laser system with temporally tailored pulse shaping capability and up to 62 mJ pulses, with the expectation the system can scale to higher pulse energies. This hybrid system consists of a low power fiber seed and pre-amplifier, and a solid state thin-disk regenerative amplifier. This system has been designed to generate high power temporally tailored pulses on the nanosecond time scale. Temporal tailoring and spectral control are performed in the low power fiber portion of the system with the high pulse energy being generated in the regenerative amplifier. The seed system consists of a 1030 nm fiber-coupled diode, which is transmitted through a Mach-Zehnder-type modulator in order to temporally vary the pulse shape. Typical pulses are 20-30 ns in duration and have energies of ~0.2 nJ from the modulator. These are amplified in a fiber pre-amplifier stage to ~100 nJ before being used to seed the free-space Yb:YAG thin-disk regenerative amplifier. Output pulses have maximum demonstrated pulse energies of 62 mJ with 20 ns pulse after ~250 passes in the cavity. The effects of thermal distortion in laser and passive optical materials are also. Generally the development of high power and high energy lasers is limited by thermal management strategies, as thermally-induced distortions can degrade laser performance and potentially cause catastrophic damage. Novel materials, such as optical ceramics, can be used to mitigate thermal distortions; however, thorough analysis is required to optimize their fabrication and minimize thermal distortions. Using a Shack-Hartmann wavefront sensor (SHWFS), it is possible to analyze the distortion induced in passive and doped optical elements by high power lasers. For example, the thin-disk used in the regenerative amplifier is examined in-situ during CW operation (up to 2 kW CW pump power). Additionally, passive oxide-based optical materials and Yb:YAG optical ceramics are also examined by pumping at 2 and 1 ?m respectively to induce thermal distortions which are analyzed with the SHWFS. This method has been developed as a diagnostic for the relative assessment of material quality, and to grade differences in ceramic laser materials associated with differences in manufacturing processes and/or the presence of impurities. In summation, this dissertation presents a high energy 1 ?m laser system which is novel in its combination of energy level and temporal tailoring, and an analysis of thermal distortions relevant to the development of high power laser systems.
Show less - Date Issued
- 2013
- Identifier
- CFE0004961, ucf:49588
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004961
- Title
- The Yugoslav peoples fight to live.
- Creator
-
Tito, Josip Broz
- Date Issued
- 1944
- Identifier
- 1927050, CFDT1927050, ucf:4803
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/1927050
- Title
- Yugoslavia: The U. N. : cooperation must be desired.
- Creator
-
Kardelj, Edvard
- Date Issued
- 1948
- Identifier
- 2683761, CFDT2683761, ucf:5135
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/2683761
- Title
- ZERO TOLERANCE FOR SOME:THE ROLE OF RACE IN ZERO TOLERANCE EXCLUSIONARY DISCIPLINE.
- Creator
-
Bejarano, Meghan, Ford, Jason, University of Central Florida
- Abstract / Description
-
Within the last few decades, zero tolerance policies and exclusionary discipline have become the standard way in which schools manage student behavior. These policies, namely suspension and expulsion have been shown to have negative impacts on the lives of students who are punished with them. Educationally, the removal of students from the classroom hurts their chances of achieving academic success. Furthermore, these policies have been linked with an increase in the presence of law...
Show moreWithin the last few decades, zero tolerance policies and exclusionary discipline have become the standard way in which schools manage student behavior. These policies, namely suspension and expulsion have been shown to have negative impacts on the lives of students who are punished with them. Educationally, the removal of students from the classroom hurts their chances of achieving academic success. Furthermore, these policies have been linked with an increase in the presence of law enforcement on school campuses, which results in the arrest of students, burdening them with expensive and serious legal battles. This research examines whether nonwhite students are more likely to be sanctioned by this form of discipline. A nationally representative sample of middle and high school students is used to estimate four logistic regression models, with exclusionary discipline as the dependent variable and race as the primary independent variable. The analysis shows that nonwhite students are more likely to suspended or expelled than white students - even when student behavior is the same. This research adds to the existing body of research on exclusionary discipline and provides a nationally generalizable study to support the claim the nonwhite students are at an increased risk to be sanctioned by zero tolerance policies.
Show less - Date Issued
- 2014
- Identifier
- CFH0004643, ucf:45276
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFH0004643
- Title
- Zika virus-induced lysis of cervical cancer cells.
- Creator
-
Krishnapura, Harini, Alexander, Kenneth, Parks, Griffith, Jewett, Mollie, University of Central Florida
- Abstract / Description
-
Cervical cancer is the fourth most frequent cancer in women with an estimated 570,000 new cases globally in 2018. Treatment of advanced cervical cancer is often unsuccessful leading to high cancer-related mortality rates, especially in under-resourced countries. Recently, a possible role for the cell surface glycoprotein CD24 in host cell specificity of Zika virus was reported. As an extension of this work, Zika viruses have been proposed as oncolytic therapy for the treatment of...
Show moreCervical cancer is the fourth most frequent cancer in women with an estimated 570,000 new cases globally in 2018. Treatment of advanced cervical cancer is often unsuccessful leading to high cancer-related mortality rates, especially in under-resourced countries. Recently, a possible role for the cell surface glycoprotein CD24 in host cell specificity of Zika virus was reported. As an extension of this work, Zika viruses have been proposed as oncolytic therapy for the treatment of neuroblastoma and other CD24 positive tumors. To determine the permissiveness of cervical cancer cells to Zika virus infection and its association with CD24, we assessed cytopathic effect (CPE) induced by Zika virus in cervical cancer cell lines (HeLa, SiHa and CaSki) by light microscopy and by cytotoxicity assay. Cervical cancer cells were susceptible to Zika virus-induced apoptosis. Upon infection, the morphology of cervical cancer cells changed, exhibiting Zika virus-induced CPE. Cervical cancer cell expression of viral non-structural protein 1 (NS1) after infection demonstrated viral protein translation. Quantitative plaque assays demonstrated the production of competent virions. Because CD24 expression was found to be important for Zika virus infection in neuroblastoma cells, CD24 expression was assessed in cervical cancer cells. Cervical cancer cells expressed low but measurable levels of CD24 mRNA and protein. siRNA-mediated knockdown of CD24 resulted in reduced NS1 expression and reduced levels of virus-induced apoptosis. Taken together our data suggest a possible role for CD24 in Zika virus-induced apoptosis in cervical cancer cells. Zika virus-induced apoptosis of cultured cervical cancer cells presents the possibility for the use of Zika virus as a potential oncolytic therapy for cervical cancer.
Show less - Date Issued
- 2019
- Identifier
- CFE0007480, ucf:52682
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0007480
- Title
- ZINC CADMIUM SULPHIDE AND ZINC SULPHIDE AS ALTERNATIVE HETEROJUNCTION PARTNERS FOR CIGS2 SOLAR CELLS.
- Creator
-
Kumar, Bhaskar, Dhere, Neelkanth G, University of Central Florida
- Abstract / Description
-
Devices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS...
Show moreDevices with ZnCdS/ZnS heterojunction partner layer have shown better blue photon response due to higher band gap of these compounds as compared to devices with CdS heterojunction partner layer. CdS heterojunction partner layer has shown high photovoltaic conversion efficiencies with CIGS absorber layer while efficiencies are lower with CuIn1-xGaxS2 (CIGS2). A negative conduction band offset has been observed for CdS/CIGS2 as compared to near flat conduction band alignment in case of CdS/CIGS devices, which results in higher interface dominated recombination. Moreover, it has been predicted that optimum band offsets for higher efficiency solar cells may be achieved for cells with alternative heterojunction partner such as ZnS. With varying ratio of Zn/ (Zn+Cd) in ZnxCd1-xS a range of bandgap energies can be obtained and thus an optimum band offset can be engineered. For reducing interface dominated recombination better lattice match between absorber and heterojunction partners is desirable. Although CdS has better lattice match with CuIn1-xGaxS2 absorber layer, same is not true for CuIn1-xGaxS2 absorber layers. Utilizing ZnxCd1-xS as heterojunction partner provides a range of lattice constant (between aZnS= ~5.4 Ǻ and aCdS= ~5.7 Ǻ) depending on Zn/(Zn+Cd). Therefore better lattice match can be obtained between heterojunction partner and absorber layer. Better lattice match will lead to lower interface dominated recombination, hence higher open circuit voltages. In the present study chemical bath deposition parameters are near optimized for high efficiency CIGS2 Solar cells. Effect of various chemical bath deposition parameters on device performance was studied and attempts were made to optimize the deposition parameters in order to improve the device performance.In/(In+Ga) ratio in absorber layer is varied to obtain good lattice match and optimum band alignment. Solar cells with conversion efficiencies comparable to conventional CdS/CIGS2 has been obtained with ZnxCd1-xS /CIGS2. High short current as well as higher open circuit voltages were obtained with ZnxCd1-xS as alternative heterojunction partner for CIGS2 solar cells as compared to SLG/Mo/CIGS2/ CdS / i-ZnO/ZnO:Al.
Show less - Date Issued
- 2007
- Identifier
- CFE0001936, ucf:47469
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0001936
- Title
- Zinc Sulfide:manganese doped Quantum rods for detection of metal ions and a business model for future sales.
- Creator
-
Teblum, Andrew, Santra, Swadeshmukul, Gesquiere, Andre, Soskin, Mark, University of Central Florida
- Abstract / Description
-
Hexavalent chromium is an extremely carcinogenic chemical that has been widely produced in the United States. This has led to major waste contamination and pollution throughout the country. According to the Environmental Working Group Hexavalent chromium has been found in 89% of city tap water. Most people believe they are safe using regular home filter systems however that is not true. A more expensive ion exchange water treatment unit is required. Therefore to protect yourselves from this...
Show moreHexavalent chromium is an extremely carcinogenic chemical that has been widely produced in the United States. This has led to major waste contamination and pollution throughout the country. According to the Environmental Working Group Hexavalent chromium has been found in 89% of city tap water. Most people believe they are safe using regular home filter systems however that is not true. A more expensive ion exchange water treatment unit is required. Therefore to protect yourselves from this carcinogenic metal a reliable test is required. In this study we have developed a Zinc Sulfide Manganese doped Quantum Rod technology to detect for presence of chromate and other harmful transitional metals in drinking water. Quantum Rods were synthesized using a hydrothermal reaction method. They were fully characterized using UV-visible absorption spectroscopy, fluorescence emission spectroscopy, X-ray Photoelectric Spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HRTEM). Quantum Rod metal detection studies were done with 28 different ions in a 96-well fluorescent plate reader. Results show that highest sensitivity to 8 ions including the toxic ions of chromate and mercury allowing us to create a sensor to detect these items.
Show less - Date Issued
- 2014
- Identifier
- CFE0005268, ucf:50569
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0005268
- Title
- ZINC-FINGER PROTEIN MCPIP IN CELL DEATH AND DIFFERENTIATION.
- Creator
-
Younce, Craig, Kolattukudy, Pappachan, University of Central Florida
- Abstract / Description
-
Monocyte chemotactic protein-1 (MCP-1) plays a critical role in the development of cardiovascular diseases. How MCP-1 contributes to the development of heart disease is not understood. We present evidence that MCP-1 causes death in cardiac myoblasts, H9c2 by inducing oxidative stress, ER stress and autophagy via a novel Zn-finger protein, MCP-1 induced protein (MCPIP). MCPIP expression caused cell death and knockdown of MCPIP, attenuated MCP-1 induced cell death. Expression of MCPIP resulted...
Show moreMonocyte chemotactic protein-1 (MCP-1) plays a critical role in the development of cardiovascular diseases. How MCP-1 contributes to the development of heart disease is not understood. We present evidence that MCP-1 causes death in cardiac myoblasts, H9c2 by inducing oxidative stress, ER stress and autophagy via a novel Zn-finger protein, MCP-1 induced protein (MCPIP). MCPIP expression caused cell death and knockdown of MCPIP, attenuated MCP-1 induced cell death. Expression of MCPIP resulted in induction of iNOS and production of reactive oxygen (ROS). It caused induction of NADPH oxidase subunit phox47 and its translocation to the cytoplasmic membrane. Oxidative stress led to the induction of ER stress markers HSP40, PDI, GRP78 and IRE1α. ER stress lead to autophagy as indicated by beclin-1 induction, cleavage of LC3 to LCII and autophagolysosome formation. Here, MCPIP-induced processes lead to apoptosis as indicated by caspase 3 activation and TUNEL assay. This cell death involved caspase 2 and caspase 12 as specific inhibitors of these caspases prevented MCPIP-induced cell death. Inhibitors of oxidative stress inhibited ER stress, and cell death. Specific inhibitors of ER stress inhibited autophagy and cell death. Inhibition of autophagy inhibited cell death. Microarray analysis showed that MCPIP expression caused induction of a variety of genes known to be involved in cell death. MCPIP caused activation of JNK and p38 and induction of p53 and PUMA. These results collectively suggest that MCPIP induces ROS/RNS production that causes ER stress which leads to autophagy and apoptosis through caspase 2/12 and IRE1α –JNK/p38-p53-PUMA pathway. These results provide the first molecular insights into the mechanism by which elevated MCP-1 levels associated with chronic inflammation may contribute to the development of heart failure. A role for inflammation and MCP-1 in obesity and diabetes has been implicated. Adipogenesis is a key process involved in obesity and associated diseases such as type 2 diabetes. This process involves temporally regulated genes controlled by a set of transcription factors, C/EBPβ, C/EBPδ, C/EBPα, and PPARγ. Currently PPARγ is considered the master regulator of adipogenesis as no known factor can induce adipogenesis without PPARγ. We present evidence that a novel Zn-finger protein, MCPIP, can induce adipogenesis without PPARγ. Classical adipogenesis-inducing medium induces MCP-1 production and MCPIP expression in 3T3-L1 cells before the induction of the C/EBP family of transcription factors and PPARγ. Knockdown of MCPIP prevents their expression and adipogenesis. Treatment of 3T3-L1 cells with MCP-1 or forced expression of MCPIP induces expression of C/EBPβ, C/EBPδ, C/EBPα, PPARγ and adipogenesis without any other inducer. Forced expression of MCPIP induces adipogenesis in PPARγ-/- fibroblasts. Thus, MCPIP is a newly identified master controller that can induce adipogenesis without PPARγ. Heart failure is a major cause of death in diabetic patients. Hyperglycemia is a major factor associated with diabetes that causes cardiomyocyte apoptosis that leads to diabetic cardiomyopathy. Cardiomyoycte apoptosis is a key event involved in the pathophysiological progression of diabetic cardiomyopathy. We have recently found that in ischemic hearts, MCP-1 can induce the zinc-finger protein, MCP-1 induced protein (MCPIP) that causes cardiomyocyte apoptosis. Although there is evidence that inflammation may play a role in diabetic cardiomyopathy, the underlying mechanisms are poorly understood. In this study, we show that treatment of H9c2 cardiomyoblasts and Neonatal Rat Ventricular Myocytes (NRVM) with 28mmol/L glucose concentration results in the induction of both transcript and protein levels of MCP-1 and MCPIP. Inhibition of MCP-1 interaction with CCR2 via specific antibody or with the G-coupled receptor inhibitors propagermanium and pertussis toxin attenuated glucose-induced cell death. Knockdown of MCPIP with specific siRNA yielded similar results. Treatment of cells with 28mmol/L glucose resulted in increased ROS production and phox47 activation. Knockdown of MCPIP attenuated these effects. The increased ROS production observed in H9c2 cardiomyoblasts and NRVM's resulted in increased ER stress proteins GRP78 and PDI. Knockdown of MCPIP attenuated expression of both GRP78 and PDI. Inhibition of ER stress with TUDC and 4'PBA prevented high glucose-induced cell death death. Treatment of cells with 28mmol/l glucose resulted in autophagy as determined by an increase in expression of beclin-1 and through increased cleavage of LC3I to LC3II. Knockdown of MCPIP attenuated expression of beclin-1 and prevented cleavage of LC3. Addition of the autophagy inhibitors 3'methyladenine and LY294002 attenuated high glucose-induced H9c2 cardiomyoblast death. We conclude that high glucose-induced H9c2 cardiomyoblast death is mediated via MCP-1 induction of MCPIP that results in ROS that leads to ER stress that causes autophagy and eventual apoptosis.
Show less - Date Issued
- 2009
- Identifier
- CFE0002888, ucf:48027
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0002888
- Title
- Zionism: Address at the Hippodrome meeting Jun 8, 1936.
- Creator
-
Browder, Earl
- Date Issued
- 1936
- Identifier
- 359826, CFDT359826, ucf:5221
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/359826
- Title
- Zionism and the arab revolution: The myth of progressive Israel.
- Creator
-
Young Socialist Alliance
- Date Issued
- 1967
- Identifier
- 2667390, CFDT2667390, ucf:4993
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/2667390
- Title
- Zionism and the Israeli state.
- Creator
-
Hochman, Larry
- Date Issued
- c1960
- Identifier
- 1927049, CFDT1927049, ucf:4802
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/1927049
- Title
- Zionism today: The Zionist movement Labor Zionism Palestine realities. Questions and answers..
- Creator
-
Novik, P.
- Date Issued
- 1936
- Identifier
- 359820, CFDT359820, ucf:5215
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/FCLA/DT/359820
- Title
- Zooming In On The Money Shot: An Exploratory Quantitative Analysis of Pornographic Film Actors.
- Creator
-
O'Neal, Erin, Huff-Corzine, Lin, Corzine, Harold, Pritchard, Adam, Potter, Roberto, University of Central Florida
- Abstract / Description
-
Sex work is one of the rare elements of our society that is both accepted and stigmatized. Ironically enough, it is stigmatized without being studied in depth. The truth is we know very little about sex work and even less about pornography(-)the most legal of genres. While researchers have spent a great deal of time determining the effects that pornography has on viewers, particularly juvenile viewers, little research has been done on the men and women who make pornography. A 43 question...
Show moreSex work is one of the rare elements of our society that is both accepted and stigmatized. Ironically enough, it is stigmatized without being studied in depth. The truth is we know very little about sex work and even less about pornography(-)the most legal of genres. While researchers have spent a great deal of time determining the effects that pornography has on viewers, particularly juvenile viewers, little research has been done on the men and women who make pornography. A 43 question survey was created and disseminated to those in the pornographic film industry, both amateur and professional, resulting in 210 respondents from all walks of life. The results of the inquiry show that social scientists know relatively little about working in pornography, having a profound impact on the current discussion and future research. Additionally, this investigation presents a new and creative method for surveying hard to reach, hidden, or sensitive subject populations that will aid in aspects of future research on sex work and other stigmatized behaviors.
Show less - Date Issued
- 2016
- Identifier
- CFE0006365, ucf:51532
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006365
- Title
- Zooplankton abudance and diversity in central Florida grass carp ponds.
- Creator
-
Fry, Douglas Lee, Osborne, John A., Natural Sciences
- Abstract / Description
-
Florida Technological University College of Natural Sciences Thesis; The effect of the Asian grass carp (Ctenopharyngodon idella Val.) and aquatic vegetation upon the zooplankton in four adjacent experimental ponds (0.139 ha each) was studied for one year. Zooplankton were collected with a newly designed shallow-water sampler. Pond 1 contained no aquatic vegetation. Ponds 2, 3, and 4 contained nine species of rooted aquatic plants. Grass carp were stocked into Pond 2 (65 per ha) and Pond 3 ...
Show moreFlorida Technological University College of Natural Sciences Thesis; The effect of the Asian grass carp (Ctenopharyngodon idella Val.) and aquatic vegetation upon the zooplankton in four adjacent experimental ponds (0.139 ha each) was studied for one year. Zooplankton were collected with a newly designed shallow-water sampler. Pond 1 contained no aquatic vegetation. Ponds 2, 3, and 4 contained nine species of rooted aquatic plants. Grass carp were stocked into Pond 2 (65 per ha) and Pond 3 (611 per ha). Physicochemical parameters were similar among the ponds. Eighty-eight zooplankton species were enumerated. The abundance of zooplankton groups (Rotifera, Cladoceza, and Copepoda) was not significantly different among the ponds containing grass carp. No significant differences existed between Pond 3 (high grass carp stocking rate) and Pond 4 (no carp) for species diversity (d) and species dominance. The number of species and species diversity (d) was found to be significantly different in Pond 2 (low grass carp stocking rate) when compared to Ponds 3 and 4; those differences probably were not due to the grass carp. Grass carp did not appear to affect the water quality of the ponds. In general, it was concluded that grass carp had little, if any, direct or indirect affect upon the zooplankton. Species commonness was greatest among ponds containing vegetation. Rotifers were the dominant zooplankton group in those ponds. Zooplankton ware moat abundant in the pond without vegetation and were dominated by copepods (notably Tropocyclops prasinus). That pond contained the lowest number of species and had the largest species diversity (d) of the ponds. The annual mean for the Simpson Index (species dominance) was highest in Pond 1. The lack of vegetation may have influenced the abundance and diversity of the zooplankton in Pond 1 compared to the other ponds. Those differences also may have been due to selective predation by mosquitofish (Gambusia affinis); that fish was significantly less abundant in Pond 1.
Show less - Date Issued
- 1978
- Identifier
- CFR0004339, ucf:52999
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFR0004339
- Title
- Zora.
- Creator
-
Tyrrell, Genevieve, Roney, Lisa, Rushin, Patrick, Scott, John, University of Central Florida
- Abstract / Description
-
This mixed-media memoir uses a variety of forms from short epigrammatic essays to straightforward stories and graphic narratives to explore the author's coming-of-age experiences augmented by chronic illness. Trying to succeed in the film industry, romance, and family situations, the young female narrator navigates the often unexpected or disappointing consequences of having an autonomic nervous system disorder. Relationships between conflicting identities emerge(-)between healthy versus sick...
Show moreThis mixed-media memoir uses a variety of forms from short epigrammatic essays to straightforward stories and graphic narratives to explore the author's coming-of-age experiences augmented by chronic illness. Trying to succeed in the film industry, romance, and family situations, the young female narrator navigates the often unexpected or disappointing consequences of having an autonomic nervous system disorder. Relationships between conflicting identities emerge(-)between healthy versus sick self, projected/envisioned versus actual self, and tough versus vulnerable self(-)as the narrator journeys toward a more complete and accepting self-understanding.
Show less - Date Issued
- 2013
- Identifier
- CFE0004763, ucf:49777
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0004763
- Title
- ZrB2-SiC BASED ULTRA HIGH TEMPERATURE CERAMIC COMPOSITES: MECHANICAL PERFORMANCE AND MEASUREMENT AND DESIGN OF THERMAL RESIDUAL STRESSES FOR HYPERSONIC VEHICLE APPLICATIONS.
- Creator
-
Stadelmann, Richard, Orlovskaya, Nina, Kumar, Ranganathan, Raghavan, Seetha, University of Central Florida
- Abstract / Description
-
Ultra-high temperature ceramics (UHTCs), such as ZrB2-based ceramic composites, have been identified as next generation candidate materials for leading edges and nose cones in hypersonic air breathing vehicles. Mechanical performance of ceramic composites play an important role in the ultra-high temperature applications, therefore SiC is added to ZrB2 as a strengthening phase to enhance its mechanical performance. The high melting temperatures of both ZrB2 and SiC, as well as the ability of...
Show moreUltra-high temperature ceramics (UHTCs), such as ZrB2-based ceramic composites, have been identified as next generation candidate materials for leading edges and nose cones in hypersonic air breathing vehicles. Mechanical performance of ceramic composites play an important role in the ultra-high temperature applications, therefore SiC is added to ZrB2 as a strengthening phase to enhance its mechanical performance. The high melting temperatures of both ZrB2 and SiC, as well as the ability of SiC to form SiO2 refractory oxide layers upon oxidation make ZrB2-SiC ceramics very suitable for aerospace applications. Thermal residual stresses appearing during processing are unavoidable in sintered ZrB2-SiC ceramic composites. Residual microstresses appear at the microstructural level (intergranular microstresses) or at the crystal structure level (intragranular microstresses). These microstresses are of enormous importance for the failure mechanisms in ZrB2-SiC ceramics, such as ratio of the trans- and intergranular fracture; crack branching or bridging, microcracking, subcritical crack growth and others, as they govern crack propagation(-)induced energy dissipation and affect the toughness and strength of the ceramic material. Therefore, understanding the evolution of residual stress state in processed ZrB2-SiC ceramic composites and accurate measurements of these stresses are of high priority. In the present research the ZrB2-17vol%SiC, ZrB2-32vol%SiC, and ZrB2-45vol%SiC ultra-high temperature particulate ceramic composites were sintered using both Hot Pressing (HP) and Spark Plasma Sintering (SPS) techniques. The mechanical performance of the ZrB2-SiC composites was investigated using 3- and 4-point bending techniques for measurements of instantaneous fracture strength and fracture toughness. Resonant Ultrasound Spectroscopy was used for measurement of Young's, shear, and bulk moduli as well as Poisson's ratio of the composites. The distribution of thermal residual stresses and the effect of the applied external load on their re-distribution was studied using micro-Raman spectroscopy. Piezospectroscopic coefficients were determined for all compositions of ZrB2-SiC ceramic under study and their experimentally obtained values were compared with the piezospectroscopic coefficients both published in the literature and calculated using theoretical approach. Finally, the novel ZrB2-IrB2-SiC ceramic composites were also produced using Spark Plasma Sintering (SPS), where IrB2 powder was synthesized using mechanochemical route. It is expected that the IrB2 additive phase might contribute to the improved overall oxidation resistance of ZrB2 based ultra-high temperature ceramic composites.
Show less - Date Issued
- 2015
- Identifier
- CFE0006008, ucf:51004
- Format
- Document (PDF)
- PURL
- http://purl.flvc.org/ucf/fd/CFE0006008
