The student voice as contributor to quality education through institutional design

The inclusion of students’ voices in different aspects of quality has evolved over the years. Consequently, students take on different roles – ranging from providing feedback on their educational experiences, to actively participating or even leading change initiatives. In making claims for different ways of conceptualising or including students’ voices, the literature often criticises some forms of engagement with student voices in favour of another. This article is based on the premise that the complexity of quality outcomes in higher education needs to be complemented by a variety of inputs from students. By drawing from examples of two high-impact practices from the University of the Free State, the article further argues for using different forms of student voices to inform how we design institutional support structures to ultimately enhance the quality of students’ educational experiences. At its core, this cyclical interaction between students’ voices and institutional design revolves around evidence – thereby contributing to the quality of educational outcomes, and ultimately students’ success

Field tuned critical fluctuations in YFe2Al10: Evidence from magnetization, 27Al (NMR, NQR) investigations

We report magnetization, specific heat, and NMR investigations on YFe2Al10 over a wide range in temperature and magnetic field and zero field (NQR) measurements. Magnetic susceptibility, specific heat and spin-lattice relaxation rate divided by T (1/T1T) follow a weak power law (T^-0.4) temperature dependence, which is a signature of critical fluctuations of Fe moments. The value of the Sommerfeld-Wilson ratio and linear relation between 1/T1T and chi(T) suggest the existence of ferromagnetic correlations in this system. No magnetic ordering down to 50 mK in Cp(T) and the unusual temperature and field scaling of the bulk and NMR data are associated with a magnetic instability which drives the system to quantum criticality. The magnetic properties of the system are tuned by field wherein ferromagnetic fluctuations are suppressed and a crossover from quantum critical to FL behavior is observed with increasing magnetic field

Ergosterol Concentration of Several Different Saccharomyces cerevisiae Yeast Strains

Differences in the formation of ergosterol in yeast cells have been found amongst several wine yeast strains used in South Africa. A higher ergosterol content is generally accompanied by a faster fermentation rate and results in a shortening of fermentation time. A high ergosterol concentration in the cell is not a prerequisite for maximal cell formation, but probably affects the metabolic activity of the cell. Aeration of the must during the yeast proliferation stage, brought about marked increases in ergosterol concentrations

Desarrollo larvario de Dagetichthys marginatus (Familia: Soleidae) a partir de puesta inducida por hormonas en condiciones de cultivo artificiales

Dagetichthys marginatus (formerly Synaptura marginata) larvae were laboratory-reared from wild caught adult broodstock as part of an aquaculture research project in temperate South Africa. A larval description for the species is provided in this paper. This work also represents the first larval description for the genus Dagetichthys, which is represented by five species, three of which occur in the western Indian Ocean. Larval development in D. marginatus is typical of Soleidae. Dagetichthys marginatus larvae are heavily pigmented, with four characteristic melanophore “blotches” on the finfold. These larvae are easily distinguished from other soleid larvae commonly encountered in temperate South Africa based on the large size at flexion (5-7.06 mm BL) and the heavily pigmented body. Laboratory-reared postflexion larvae in this study showed similar meristic counts to those of wild caught adult fish. Despite the common occurrence of mature adults of this species in shallow marine waters off temperate South Africa, larvae are absent from nearshore ichthyoplankton catches. As yet, the spawning strategy of the species is unknown.Las larvas de Dagetichthys marginatus (anteriormente Synaptura marginata) se cultivaron en el laboratorio a partir de adultos capturados en el medio natural como parte de un proyecto de investigación en la zona templada de Sudáfrica. En este trabajo se presenta la descripción de las larvas de esta especie. Este trabajo también representa la primera descripción del Dagetichthys, representado por cinco especies, tres de las cuales se encuentran en el Oeste del Océano Índico. El desarrollo larvario de D. marginatus es el típico de la familia Soleidae. Las larvas de Dagetichthys marginatus están fuertemente pigmentadas con cuatro característicos bloques de melanóforos en la aleta primordial. Estas larvas se distinguen fácilmente de otras larvas de soleidos comúnmente encontradas en la zona templada de Sudáfrica en base a su gran longitud en el estadio de flexión (5-7.06 mm BL) y a su cuerpo fuertemente pigmentado. Las larvas en estado de postflexión obtenidas en el presente cultivo mostraron similares contajes que los adultos capturados en el medio natural. A pesar de la común aparición, en aguas someras, de adultos maduros de esta especie frente a la zona templada de Sudáfrica, las larvas estuvieron ausentes en las muestras de ictioplanton recolectadas en dicha zona. Hasta el momento, la estrategia de puesta de esta especie es desconocida.

Contiguous 3d and 4f magnetism: towards strongly correlated 3d electrons in YbFe2Al10

We present magnetization, specific heat, and 27Al NMR investigations on YbFe2Al10 over a wide range in temperature and magnetic field. The magnetic susceptibility at low temperatures is strongly enhanced at weak magnetic fields, accompanied by a ln(T0/T) divergence of the low-T specific heat coefficient in zero field, which indicates a ground state of correlated electrons. From our hard X-ray photo emission spectroscopy (HAXPES) study, the Yb valence at 50 K is evaluated to be 2.38. The system displays valence fluctuating behavior in the low to intermediate temperature range, whereas above 400 K, Yb3+ carries a full and stable moment, and Fe carries a moment of about 3.1 mB. The enhanced value of the Sommerfeld Wilson ratio and the dynamic scaling of spin-lattice relaxation rate divided by T [27(1/T1T)] with static susceptibility suggests admixed ferromagnetic correlations. 27(1/T1T) simultaneously tracks the valence fluctuations from the 4f -Yb ions in the high temperature range and field dependent antiferromagnetic correlations among partially Kondo screened Fe 3d moments at low temperature, the latter evolve out of an Yb 4f admixed conduction band.Comment: To appear in Phys. Rev. Let

CeRu4_4Sn6_6: heavy fermions emerging from a Kondo-insulating state

The combination of low-temperature specific-heat and nuclear-magnetic-resonance (NMR) measurements reveals important information of the ground-state properties of CeRu$_4$Sn$_6$, which has been proposed as a rare example of a tetragonal Kondo-insulator (KI). The NMR spin-latticerelaxation rate $1/T_1$ deviates from the Korringa law below 100 K signaling the onset of an energy gap $\Delta E_g1/k_B \simeq 30$K. This gap is stable against magnetic fields up to 10 T. Below 10 K, however, unusual low-energy excitations of in-gap states are observed, which depend strongly on the field H. The specific heat C detects these excitations in the form of an enhanced Sommerfeld coefficient $\gamma = C(T)/T$ : In zero field, $\gamma$ increases steeply below 5 K, reaching a maximum at 0.1 K, and then saturates at $\gamma = 0.6$ J/molK$^2$. This maximum is shifted to higher temperatures with increasing field suggesting a residual density of states at the Fermi level developing a spin gap $\Delta E_g2$. A simple model, based on two narrow quasiparticle bands located at the Fermi level - which cross the Fermi level in zero field at 0.022 states/meV f.u. - can account qualitatively as well as quantitatively for the measured observables. In particular, it is demonstrated that fitting our data of both specific heat and NMR to the model, incorporating a Ce magnetic moment of $\mu = \Delta E_g1/\mu_{0H} \simeq 1 \mu_B$, leads to the prediction of the field dependence of the gap. Our measurements rule out the presence of a quantum critical point as the origin for the enhanced $\gamma$ in CeRu$_4$Sn$_6$ and suggest that this arises rather from correlated, residual in-gap states at the Fermi level. This work provides a fundamental route for future investigations into the phenomenon of narrow-gap formation in the strongly correlated class of systemComment: 11 pages, 13 figure

Structural and magnetic properties of E-Fe_{1-x}Co_xSi thin films deposited via pulsed laser deposition

We report pulsed laser deposition synthesis and characterization of polycrystalline Fe1-xCox Si thin films on Si (111). X-ray diffraction, transmission electron, and atomic force microscopies reveal films to be dense, very smooth, and single phase with a cubic B20 crystal structure. Ferromagnetism with significant magnetic hysteresis is found for all films including nominally pure FeSi films in contrast to the very weak paramagnetism of bulk FeSi. For Fe1-xCoxSi this signifies a change from helimagnetism in bulk, to ferromagnetism in thin films. These ferromagnetic thin films are promising as a magnetic-silicide/silicon system for polarized current production, manipulation, and detection.Comment: 12 pages, 4 figures accepted in the Applied Physics Letter

Incommensurate spin-density-wave antiferromagnetism in CeRu2Al2B

The newly discovered Ising-type ferromagnet CeRu2Al2B exhibits an additional phase transition at TN=14.2 K before entering the ferromagnetic ground state at TC=12.8 K. We clarify the nature of this transition through high resolution neutron diffraction measurements. The data reveal the presence of a longitudinal incommensurate spin-density wave (SDW) in the temperature range of TC<T<TN. The propagation vector q∼(0,0,0.148) is nearly temperature independent in this region and discontinuously locks into q=0 at TC. Mean-field calculations of an effective Ising model indicate that the modulated SDW phase is stabilized by a strong competition between ferromagnetic and antiferromagnetic exchange interactions. This makes CeRu2Al2B a particularly attractive model system to study the global phase diagram of ferromagnetic heavy-fermion metals under the influence of magnetic frustration

Anisotropic optical conductivity of the putative Kondo insulator CeRu4_4Sn6_6

Kondo insulators and in particular their non-cubic representatives have remained poorly understood. Here we report on the development of an anisotropic energy pseudogap in the tetragonal compound CeRu$_4$Sn$_6$ employing optical reflectivity measurements in broad frequency and temperature ranges, and local density approximation plus dynamical mean field theory calculations. The calculations provide evidence for a Kondo insulator-like response within the $a-a$ plane and a more metallic response along the c axis and qualitatively reproduce the experimental observations, helping to identify their origin