13,296 research outputs found
Finite Higgs mass without Supersymmetry
We identify a class of chiral models where the one-loop effective potential
for Higgs scalar fields is finite without any requirement of supersymmetry. It
corresponds to the case where the Higgs fields are identified with the
components of a gauge field along compactified extra dimensions. We present a
six dimensional model with gauge group U(3)xU(3) and quarks and leptons
accomodated in fundamental and bi-fundamental representations. The model can be
embedded in a D-brane configuration of type I string theory and, upon
compactification on a T^2/Z_2 orbifold, it gives rise to the standard model
with two Higgs doublets.Comment: 28 pages, 4 figures, uses axodraw. Some typos corrected and
references rearrange
Resistance to group clinical supervision: a semistructured interview study of non-participating mental health nursing staff members
This paper is a report of an interview study exploring personal views on participating in group clinical supervision among mental health nursing staff members who do not participate in supervision. There is a paucity of empirical research on resistance to supervision, which has traditionally been theorised as a supervisee’s maladaptive coping with anxiety in the supervision process. The aim of the study was to examine resistance to group clinical supervision by interviewing nurses who did not participate in supervision. In 2015, we conducted semi-structured interviews with 24 Danish mental health nursing staff members who had been observed not to participate in supervision in two periods of 3 months. Interviews were audio recorded and subjected to discourse analysis. We constructed two discursive positions taken by the informants: Forced non-participation where an informant was in favour of supervision, but presented practical reasons for not participating and Deliberate rejection, where an informant intentionally chose to not to participate in supervision. Furthermore, we described two typical themes drawn upon by informants in their positioning: Difficulties related to participating in supervision and Limited need for and benefits from supervision. The findings indicated that group clinical supervision extended a space for group discussion that generated or accentuated anxiety because of already existing conflicts and a fundamental lack of trust between group members. Many informants perceived group clinical supervision as an unacceptable intrusion, which could indicate a need for developing more acceptable types of post-registration clinical education and reflective practice for this group
Error Threshold for Color Codes and Random 3-Body Ising Models
We study the error threshold of color codes, a class of topological quantum
codes that allow a direct implementation of quantum Clifford gates suitable for
entanglement distillation, teleportation and fault-tolerant quantum
computation. We map the error-correction process onto a statistical mechanical
random 3-body Ising model and study its phase diagram via Monte Carlo
simulations. The obtained error threshold of p_c = 0.109(2) is very close to
that of Kitaev's toric code, showing that enhanced computational capabilities
does not necessarily imply lower resistance to noise.Comment: 4 pages, 3 figures, 1 tabl
Divergences in Kaluza-Klein Models and their String Regularization
Effective field theories with (large) extra dimensions are studied within a
physical regularization scheme provided by string theory. Explicit string
calculations then allow us to consistently analyze the ultraviolet sensitivity
of Kaluza--Klein theories in the presence or absence of low energy
supersymmetry.Comment: 50 pages, LaTe
Optimization of the direct synthesis of dimethyl ether from COâ‚‚ rich synthesis gas: Closing the loop between experimental investigations and model-based reactor design
Reaction kinetic modeling, model-based optimization and experimental validation are performed for the direct synthesis of dimethyl ether from CO2 rich synthesis gas. Among these disciplines, experimental methods and models are aligned in a stringent way of action, i.e., the same setup and models are applied throughout the whole contribution. First, a lumped reaction kinetic model from the literature is modified and parametrized to fit a vast array of 240 data points measured in a laboratory fixed bed reactor. The data were acquired using a mechanical mixture of the commercial catalysts CuO/ZnO/Al2O3 and Îł-Al2O3. For this setup, a predictive model is derived and applied within dynamic model-based optimization. Here, the single-pass COx conversion serves as objective function while the operating conditions and composition of the mixed catalyst bed are the optimization variables. Finally, the optimization results obtained numerically are validated experimentally verifying the identified performance enhancement qualitatively. The remaining quantitative deviations yield valuable insights into model and methodological weaknesses or inaccuracies, closing the loop between kinetic investigations, model-based optimization and experimental validation
An atlas of Calcium triplet spectra of active galaxies
We present a spectroscopic atlas of active galactic nuclei covering the
region around the 8498, 8542, 8662 Calcium triplet (CaT) lines. The sample
comprises 78 objects, divided into 43 Seyfert 2s, 26 Seyfert 1s, 3 Starburst
and 6 normal galaxies. The spectra pertain to the inner ~300 pc in radius, and
thus sample the central kinematics and stellar populations of active galaxies.
The data are used to measure stellar velocity dispersions (sigma_star) both
with cross-correlation and direct fitting methods. These measurements are found
to be in good agreement with each-other and with those in previous studies for
objects in common. The CaT equivalent width is also measured. We find average
values and sample dispersions of W_CaT of 4.6+/-2.0, 7.0 and 7.7+/-1.0
angstrons for Seyfert 1s, Seyfert 2s and normal galaxies, respectively. We
further present an atlas of [SIII]\lambda 9069 emission line profiles for a
subset of 40 galaxies. These data are analyzed in a companion paper which
addresses the connection between stellar and Narrow Line Region kinematics, the
behaviour of the CaT equivalent width as a function of sigma_star, activity
type and stellar population properties.Comment: 18 pages, 10 figures, accepted for publication in MNRA
Hong-Ou-Mandel interferometer with cavities: theory
We study the number of coincidences in a Hong-Ou-Mandel interferometer exit
whose arms have been supplemented with the addition of one or two optical
cavities. The fourth-order correlation function at the beam-splitter exit is
calculated. In the regime where the cavity length are larger than the
one-photon coherence length, photon coalescence and anti-coalescence
interference is observed. Feynman's path diagrams for the indistinguishable
processes that lead to quantum interference are presented. As application for
the Hong-Ou-Mandel interferometer with two cavities, it is discussed the
construction of an optical XOR gate
Constraints on Dimensional Warped Spaces
In order to investigate the phenomenological implications of allowing gauge
fields to propagate in warped spaces of more than five dimensions, we consider
a toy model of a space warped by the presence of a anisotropic bulk
cosmological constant. After solving the Einstein equation, three classes of
solutions are found, those in which the additional () dimensions are
growing, shrinking or remaining constant. It is found that gauge fields
propagating in these spaces have a significantly different Kaluza Klein (KK)
mass spectrum and couplings from that of the Randall and Sundrum model. This
leads to a greatly reduced lower bound on the KK scale, arising from
electroweak constraints, for spaces growing towards the IR brane.Comment: 6 pages, 5 figures PASCOS2010 International Symposium proceedin
Understanding the Links between Inferring Mental States, Empathy, and Burnout in Medical Contexts
It is generally accepted that empathy should be the basis of patient care. However, this ideal may be unrealistic if healthcare professionals suffer adverse effects when engaging in empathy. The aim of this study is to explore the effect of inferring mental states and different components of empathy (perspective-taking; empathic concern; personal distress) in burnout dimensions (emotional exhaustion; depersonalization; personal accomplishment). A total of 184 healthcare professionals participated in the study (23% male, Mage = 44.60; SD = 10.46). We measured participants’ empathy, the inference of mental states of patients, and burnout. Correlation analyses showed that inferring mental states was positively associated with perspective-taking and with empathic concern, but uncorrelated with personal distress. Furthermore, emotional exhaustion was related to greater levels of personal distress and greater levels of inferences of mental states. Depersonalization was associated with greater levels of personal distress and lower levels of empathic concern. Personal accomplishment was associated with the inference of mental states in patients, lower levels of personal distress, and perspective-taking. These results provide a better understanding of how different components of empathy and mental state inferences may preserve or promote healthcare professionals’ burnout
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