325 research outputs found
Liturgical pharmacology: Time of the question, complexity and ethics
Bernard Stiegler depicts technics as the human’s tertiary memory retention generating a pharmakon with both curative and malignant potential. He additionally rues the posthuman epoch’s depletion of a ‘time of the question’: revealed in the prevalent inaptitude for wisdom – scilicet long-term acuity. We offer Christian liturgy as an abeyant psychotechnique arcing the current pharmakon to cure through soliciting a ‘time of the question’. Rejuvenating Christian liturgy as a psychotechnique can bolster a broader societal ‘time of the question’. Firstly, we describe technic’s du jour mise on scène. Secondly, we constrain Christian liturgies as complex systems incorporating malleability, temporality, and instability. Thirdly, we imagine Christian liturgy as empty tradition allowing amateur repetition of ancient art enticing a ‘time of the question’
High resolution spectroscopy of single NV defects coupled with nearby C nuclear spins in diamond
We report a systematic study of the hyperfine interaction between the
electron spin of a single nitrogen-vacancy (NV) defect in diamond and nearby
C nuclear spins, by using pulsed electron spin resonance spectroscopy.
We isolate a set of discrete values of the hyperfine coupling strength ranging
from 14 MHz to 400 kHz and corresponding to C nuclear spins placed at
different lattice sites of the diamond matrix. For each lattice site, the
hyperfine interaction is further investigated through nuclear spin polarization
measurements and by studying the magnetic field dependence of the hyperfine
splitting. This work provides informations that are relevant for the
development of nuclear-spin based quantum register in diamond.Comment: 8 pages, 5 figure
Immunology for Clinicians: A ‘Trojan Horse’ approach
A South African website imparts basic immunology information to clinicians and other health care workers
Energy requirement for firing porcelain
Results from studies on the ternary system Ribaué kaolin–Carapira feldspar– Marracuene quartz sands were used to test a procedure that we developed for calculation of the energy requirement for firing porcelain. Results obtained vary between 1300 and 1800 kJ/kg porcelain. These results differ largely from the ones obtained using Hennicke’s procedure. KEY WORDS: Porcelain, Energy requirement for firing porcelain, Kaolin---feldspar---quartz sandsBull. Chem. Soc. Ethiop. 2004, 18(1), 73-80
Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond
The coherent behavior of the single electron and single nuclear spins of a
defect center in diamond and a 13C nucleus in its vicinity, respectively, are
investigated. The energy levels associated with the hyperfine coupling of the
electron spin of the defect center to the 13C nuclear spin are analyzed.
Methods of magnetic resonance together with optical readout of single defect
centers have been applied in order to observe the coherent dynamics of the
electron and nuclear spins. Long coherence times, in the order of microseconds
for electron spins and tens of microseconds for nuclear spins, recommend the
studied system as a good experimental approach for implementing a 2-qubit gate.Comment: 4 pages, 4 figure
Dynamical masses of brightest cluster galaxies II: constraints on the stellar IMF
We use stellar and dynamical mass profiles, combined with a stellar
population analysis, of 32 brightest cluster galaxies (BCGs) at redshifts of
0.05 0.30, to place constraints on their stellar Initial Mass
Function (IMF). We measure the spatially-resolved stellar population properties
of the BCGs, and use it to derive their stellar mass-to-light ratios
(). We find young stellar populations (200 Myr) in
the centres of 22 per cent of the sample, and constant within 15 kpc for 60 per cent of the sample. We further use the stellar
mass-to-light ratio from the dynamical mass profiles of the BCGs
(), modelled using a Multi-Gaussian Expansion (MGE)
and Jeans Anisotropic Method (JAM), with the dark matter contribution
explicitly constrained from weak gravitational lensing measurements. We
directly compare the stellar mass-to-light ratios derived from the two
independent methods, (assuming some IMF) to
for the subsample of BCGs with no young stellar
populations and constant . We find that for the
majority of these BCGs, a Salpeter (or even more bottom-heavy) IMF is needed to
reconcile the stellar population and dynamical modelling results although for a
small number of BCGs, a Kroupa (or even lighter) IMF is preferred. For those
BCGs better fit with a Salpeter IMF, we find that the mass-excess factor
against velocity dispersion falls on an extrapolation (towards higher masses)
of known literature correlations. We conclude that there is substantial scatter
in the IMF amongst the highest-mass galaxies.Comment: 15 pages, 11 figures, accepted for publication in MNRA
Genetic testing approaches for hereditary breast cancer: Perspectives from a private diagnostic laboratory
Breast cancer is highly prevalent in South Africa, and up to 10% of breast cancer cases may be hereditary. The landscape of genetic testing options for hereditary breast cancer (HBC) has changed significantly over the past decade, and healthcare providers are faced with multiple options when referring breast cancer patients for genetic testing. We have performed a retrospective study of 3 years’ worth of breast cancer genetic testing referrals to our laboratory. While Afrikaner and Ashkenazi Jewish founder screens may be appropriate as first-line tests in a limited subset of patients, we have shown that in the majority of cases it is more effective to adopt a multigene panel approach. While variants in the BRCA1 and BRCA2 genes still account for a significant proportion of cases, close to 40% of pathogenic variants were found in genes other than BRCA1 or BRCA2. There are many factors that healthcare providers should consider when requesting genetic testing for breast cancer patients and families, including family history, ancestral background, cost, medical aid scheme reimbursement and scope of testing. We summarise our findings and provide advantages and disadvantages of each approach, with the aim of assisting clinicians and genetic counsellors to make appropriate testing decisions
The dynamically hot stellar halo around NGC 3311: a small cluster-dominated central galaxy
An important open question is the relation between intracluster light and the
halos of central galaxies in galaxy clusters. Here we report results from an on
going project with the aim to characterize the dynamical state in the core of
the Hydra I (Abell 1060) cluster around NGC 3311. Methods: We analyze deep
long-slit absorption line spectra reaching out to ~25 kpc in the halo of NGC
3311. Results: We find a very steep increase in the velocity dispersion profile
from a central sigma_0=150 km/s to sigma_out ~450 km/s at R ~ 12 kpc. Farther
out, to ~25 kpc, sigma appears to be constant at this value, which is ~60% of
the velocity dispersion of the Hydra I galaxies. With its dynamically hot halo
kinematics, NGC 3311 is unlike other normal early-type galaxies. Conclusions:
These results and the large amount of dark matter inferred from X-rays around
NGC 3311 suggest that the stellar halo of this galaxy is dominated by the
central intracluster stars of the cluster, and that the transition from
predominantly galaxy-bound stars to cluster stars occurs in the radial range 4
to 12 kpc from the center of NGC 3311. We comment on the wide range of halo
kinematics observed in cluster central galaxies, depending on the evolutionary
state of their host clusters.Comment: 5 pages, 4 figures, 1 table, accepted for publication in A&
Properties of nitrogen-vacancy centers in diamond: group theoretic approach
We present a procedure that makes use of group theory to analyze and predict
the main properties of the negatively charged nitrogen-vacancy (NV) center in
diamond. We focus on the relatively low temperatures limit where both the
spin-spin and spin-orbit effects are important to consider. We demonstrate that
group theory may be used to clarify several aspects of the NV structure, such
as ordering of the singlets in the () electronic configuration, the
spin-spin and the spin-orbit interactions in the () electronic
configuration. We also discuss how the optical selection rules and the response
of the center to electric field can be used for spin-photon entanglement
schemes. Our general formalism is applicable to a broad class of local defects
in solids. The present results have important implications for applications in
quantum information science and nanomagnetometry.Comment: 30 pages, 6 figure
Resuscitating myth: Hollywood, Big History and transdisciplinary theology
Expanding our description of liturgy as an organisation of technics structuring desire, we describe the accompanying myth as a technic of knowing. Drawing on transdisciplinary theology, developed from the work of Wentzel van Huyssteen, Paul Cilliers and Alfonso Montuori, we engage the cross-disciplinary construction of scientific myth by Big Historians. We argue that myth, as a transversal technic of knowing, is abundant in many spheres of our lives and bridges what Bernard Stiegler calls the persistent minimal gap between humanity and technics. Can Big Historians offer such a bridge and what does it mean when scientists use technicities developed by religious practitioners
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