One Loop Integrals at Finite Temperature and Density

The technique of decomposing Feynman diagrams at the one loop level into elementary integrals is generalized to the imaginary time Matsubara formalism. The three lowest integrals, containing one, two and three fermion lines, are provided in a form that separates out the real and imaginary parts of these complex functions, according to the input arguments, in a fashion that is suitable for numerical evaluation. The forms given can be evaluated for arbitrary values of temperature, particle mass, particle momenta and chemical potential.Comment: 32 Pages REVTeX, 9 Figures available as separate fil

Probing the effect of point defects on the leakage blocking capability of Al0.1Ga0.9N/Si structures using a monoenergetic positron beam

Vacancy-type defects in Al0.1Ga0.9N were probed using a monoenergetic positron beam. Al0.1Ga0.9N layers with different carbon doping concentrations ([C] = 5 x 10(17) -8 x 10(19) cm(-3)) were grown on Si substrates by metalorganic vapor phase epitaxy. The major defect species in Al0.1Ga0.9N was determined to be a cation vacancy (or cation vacancies) coupled with nitrogen vacancies and/or with carbon atoms at nitrogen sites (C(N)s). The charge state of the vacancies was positive because of the electron transfer from the defects to C-N-related acceptors. The defect charge state was changed from positive to neutral when the sample was illuminated with photon energy above 1.8 eV, and this energy range agreed with the yellow and blue luminescence. For the sample with high [C], the charge transition of the vacancies under illumination was found to be suppressed, which was attributed to the trapping of emitted electrons by C-N-related acceptors. With increasing [C], the breakdown voltage under the reverse bias condition increased. This was explained by the trapping of the injected electrons by the positively charged vacancies and C-N-related acceptors

The evidence of quasi-free positronium state in GiPS-AMOC spectra of glycerol

We present the results of processing of Age-Momentum Correlation (AMOC) spectra that were measured for glycerol by the Gamma-induced positron spectroscopy (GiPS) facility. Our research has shown that the shape of experimental s(t) curve cannot be explained without introduction of the intermediate state of positronium (Ps), called quasi-free Ps. This state yields the wide Doppler line near zero lifetimes. We discuss the possible properties of this intermediate Ps state from the viewpoint of developed model. The amount of annihilation events produced by quasi-free Ps is estimated to be less than 5% of total annihilations. In the proposed model, quasi-free Ps serves as a precursor for trapped Ps of para- and ortho-states

Hadronization in the SU(3) Nambu - Jona-Lasinio model

The hadronization process for quarks combining into two mesons, q\bar q\to MM' at temperature T is described within the SU(3) Nambu- Jona-Lasinio model with finite current quark masses. Invariant matrix elements, cross-sections and transition rates are calculated to leading order in a 1/N_c expansion. Four independent classes, u\bar d, u\bar s, u\bar u and s\bar s\to hadrons are analysed, and the yield is found to be dominated by pion production. Threshold behaviour is determined by the exothermic or endothermic nature of the processes constituting the hadronization class. A strong suppression of transition rates is found at the pionic Mott temperature T_{M\pi}=212 MeV, at which the pion becomes a resonant state. The mean time for hadronization is calculated to be 2-4 fm/c near the Mott temperature. The calculation of strangeness changing processes indicates that hadronization accounts for a 1% increase in the absolute value of the kaon to pion ratio at T=150 MeV

Direct observation of twist mode in electroconvection in I52

I report on the direct observation of a uniform twist mode of the director field in electroconvection in I52. Recent theoretical work suggests that such a uniform twist mode of the director field is responsible for a number of secondary bifurcations in both electroconvection and thermal convection in nematics. I show here evidence that the proposed mechanisms are consistent with being the source of the previously reported SO2 state of electroconvection in I52. The same mechanisms also contribute to a tertiary Hopf bifurcation that I observe in electroconvection in I52. There are quantitative differences between the experiment and calculations that only include the twist mode. These differences suggest that a complete description must include effects described by the weak-electrolyte model of electroconvection

A Non-Equilibrium Defect-Unbinding Transition: Defect Trajectories and Loop Statistics

In a Ginzburg-Landau model for parametrically driven waves a transition between a state of ordered and one of disordered spatio-temporal defect chaos is found. To characterize the two different chaotic states and to get insight into the break-down of the order, the trajectories of the defects are tracked in detail. Since the defects are always created and annihilated in pairs the trajectories form loops in space time. The probability distribution functions for the size of the loops and the number of defects involved in them undergo a transition from exponential decay in the ordered regime to a power-law decay in the disordered regime. These power laws are also found in a simple lattice model of randomly created defect pairs that diffuse and annihilate upon collision.Comment: 4 pages 5 figure

Career Pathway Barriers, Strategies, and Practices of Female Superintendents in Rural Georgia: A Narrative Inquiry

I investigated six rural Georgia female school superintendents’ perceptions of trajectories into the superintendency and their roles and responsibilities as educational leaders. I examined how their life and career experiences shaped their professional roles as practicing female superintendents. This study contributes to the limited academic literature on female superintendents, focusing on the gender obstacles they overcame to find success in a male-dominated career. It also uses the voices of women in rural districts to tell their own stories. I used three conceptual lenses: feminist theory, the gatekeeping theory, and the structural empowerment theory to understand the women's main characteristics of rising to senior leadership positions in a rural school district. I developed four analytical themes from the data: 1) surviving in the male-dominated jungle of educational leadership, 2) being safer at home, 3) the paradox of female leadership, and 4) balancing work-life demands. The findings suggest that female educational leaders adapt and change their behaviors to survive a male-dominated landscape. Although female superintendents are severely underrepresented, they bring to leadership a complete range of the qualities modern leaders need, including self- awareness, resilience, creativity, humility, and authenticity. Male leaders might benefit from these unique characteristics. The research shows the strategies to address the social, political, and economic challenges females face in their day-to-day practices as superintendents. This study's findings are significant for those who mentor female educational leaders, design educational leadership programs and hire school superintendents. Keywords: female superintendents; rural Georgia; feminist theory; educational leadership; superintendents; gatekeeping theory;Chapter I: INTRODUCTION 1 -- Statement of the Problem 3 -- Purpose 5 -- Research Questions 6 -- Significance 7 -- Conceptual Framework 7 -- Researcher's Interest 8 -- Existing Theory 9 -- Summary of Methodology 12 -- Limitations 13 -- Definition of Terms 14 -- Chapter Summary 15 -- Chapter II: LITERATURE REVIEW 17 -- Conceptual Framework 18 -- Experiential Knowledge 18 -- Existing Theory and Knowledge 20 -- Theories 20 -- Historical Context 23 -- Career Pathways 26 -- Barriers for Female Superintendents 29 -- Characteristics of Female Leaders 37 -- Theories as Connected to the Concepts and Literature 43 -- Summary 44 -- Chapter III: METHODOLOGY 46 -- Research Questions 47 -- Researcher Design and Rationale 47 -- Setting 49 -- Role of Researcher 49 -- Participant Selection 50 -- Data Collection 51 -- Data Analysis 55 -- Issues of Trustworthiness 57 -- Credibility 57 -- Rich Data 58 -- Triangulation 58 -- Member Checking 58 -- Transferability 58 -- Confirmability 59 -- Ethical Procedures 59 -- Chapter Summary 60 -- Chapter IV: NARRATIVES OF FEMALE SCHOOL SUPERINTENDENTS 61 -- Profiles of Participants 63 -- Betty 63 -- Abigail 70 -- Inez 76 -- Rebekah 81 -- Dorothea 86 -- Juliet 93 -- Chapter Summary 99 -- Chapter V: DISCUSSION OF THEMES 100 -- Surviving in the Male-Dominated Leadership Jungle 106 -- Safer at Home 116 -- The Paradox of Female Leadership 123 -- Balancing Work-Life Demands 130 -- Summary 134 -- Chapter VI: CONCLUSION 135 -- Research Questions: Summary Discussion 137 -- Research Question 1… 137 -- Research Question 2 146 -- Implications 152 -- Aspiring Female Superintendents 153 -- Professional Organizations 154 -- School Districts 155 -- School Board Members 156 -- Limitations 156 -- Recommendations for Future Research 158 -- Final Conclusions 160 -- References 166 -- Appendix A: Participant Recruitment Letter 181Tsemunhu, Rudo E.Gunn, NicoleChaumba, JosphineLeech, DonaldEd.D.Educational Leadershi