Rad-hard vertical JFET switch for the HV-MUX system of the ATLAS upgrade Inner Tracker

This work presents a new silicon vertical JFET (V-JFET) device, based on the trenched 3D-detector technology developed at IMB-CNM, to be used as switches for the High-Voltage powering scheme of the ATLAS upgrade Inner Tracker. The optimization of the device characteristics is performed by 2D and 3D TCAD simulations. Special attention has been paid to the on-resistance and the switch-off and breakdown voltages to meet the specific requirements of the system. In addition, a set of parameter values has been extracted from the simulated curves to implement a SPICE model of the proposed V-JFET transistor. As these devices are expected to operate under very high radiation conditions during the whole experiment life-time, a study of the radiation damage effects and the expected degradation on the device performance is also presented at the end of the paper.Comment: KEYWORDS: Radiation-hard electronics; Voltage distributions; Large detector systems for particle and astroparticle physics. 9 Pages, 7 Figure

Quantum Phase Transition in the Itinerant Antiferromagnet (V0.9Ti0.1)2O3

Quantum-critical behavior of the itinerant electron antiferromagnet (V0.9Ti0.1)2O3 has been studied by single-crystal neutron scattering. By directly observing antiferromagnetic spin fluctuations in the paramagnetic phase, we have shown that the characteristic energy depends on temperature as c_1 + c_2 T^{3/2}, where c_1 and c_2 are constants. This T^{3/2} dependence demonstrates that the present strongly correlated d-electron antiferromagnet clearly shows the criticality of the spin-density-wave quantum phase transition in three space dimensions.Comment: 4 pages, 4 figure

Out the box : flamenco as educational : a living theory study of dance in primary education.

Thesis (M.Ed.)-University of KwaZulu-Natal, Edgewood, 2010.This study arises out of my experiences of conducting flamenco dance workshops in a number of schools. During my visits I became concerned by what I observed happening in dance education at these schools. In discussion with the teachers I began to identify various challenges and constrains that had the effect of ‘boxing’ dance in the formal education curriculum. I became concerned with the effect these ‘boxes’ were having on dance education and I felt compelled to try and address some of the issues and challenges I observed. The diversity of cultures found in many urban schools that I visited, presents a tremendous challenge for educators wishing to include dance into their learning programmes. As a result dance is either not being offered at these schools or is approached in a tokenistic way. In many instances the teachers I spoke to were inadequately trained or ignorant of the requirements for dance in the formal curriculum. This study seeks to offer a way to address these issues. In my research, I have reflected on some of the educational and social factors that I believe are challenging dance education in these schools. I have conducted a Qualitative Action Research with an Auto Ethnographic, Self Study approach using the Living Theory Methodology as a point of departure. I have used my knowledge of flamenco and dance education to open the ‘flamenco box’ in order to introduce it to mainstream dance education in South Africa. I have come to term my approach ‘flamenco as educational’. In accordance with the Living Theory Methodology I include personal and educational aims and values and through rhythm and flamenco dance reflect on the interconnectedness of existence. I use critical reflection to engage with the issues I observed influencing dance education in a multicultural learning environment

Evolution of spin-wave excitations in ferromagnetic metallic manganites

Neutron scattering results are presented for spin-wave excitations of three ferromagnetic metallic $A_{1-x}A^{\prime}_{x}$MnO$_3$ manganites (where $A$ and $A^\prime$ are rare- and alkaline-earth ions), which when combined with previous work elucidate systematics of the interactions as a function of carrier concentration $x$, on-site disorder, and strength of the lattice distortion. The long wavelength spin dynamics show only a very weak dependence across the series. The ratio of fourth to first neighbor exchange ($J_4/J_1$) that controls the zone boundary magnon softening changes systematically with $x$, but does not depend on the other parameters. None of the prevailing models can account for these behaviors.Comment: Submitted to Phys. Rev. Let

Signature of Magnetic Phase Separation in the Ground State of Pr1-xCaxMnO3

Neutron scattering has been used to investigate the evolution of the long- and short-range charge-ordered (CO), ferromagnetic (FM), and antiferromagnetic (AF) correlations in single crystals of Pr1-xCaxMnO3. The existence and population of spin clusters as refected by short-range correlations are found to drastically depend on the doping (x) and temperature (T). Concentrated spin clusters coexist with long-range canted AF order in a wide temperature range in x = 0.3 while clusters do not appear in x = 0.4 crystal. In contrast, both CO and AF order parameters in the x = 0.35 crystal show a precipitous decrease below ~ 35 K where spin clusters form. These results provide direct evidence of magnetic phase separation and indicate that there is a critical doping x_c (close to x = 0.35) that divides the phase-separated site-centered from the homogeneous bond-centered or charge-disproportionated CO ground state.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Letter

Give Me a Break: Do Mental Health Breaks from Social Networking Sites Correlate with Lower Psychopathology? - Preliminary Findings

Social networking sites (SNS) have become a pervasive part of modern society. In 2019, 69 % of adults used Facebook, and 74 % of these users checked Facebook daily. Social networking use is even higher in younger generations; 92 % of adolescents check SNS daily, and 24 % report being online “almost constantly.” Recently, a flood of research has exposed the harmful correlates of social networking site use, including increased depression, anxiety, suicidality, psychological distress, self-esteem, anxiety, and sleep problems. As the public has become aware of these adverse outcomes, a new trend of taking a break from SNS for their mental health has increased in popularity. However, no empirical research has examined how the mental health of those who have taken a SNS mental health break differs from those who have not. Therefore, this study examined the differences in personality psychopathology, self-esteem, and internalizing symptoms between these two groups in a sample of 565 adult social networking site users. It was found that individuals who took a SNS mental health break had higher self-esteem, but also higher levels of personality psychopathology and internalizing symptomology. Implications for this study are discussed