422 research outputs found
Manifestations of professional identity work: An integrative review of research in professional identity formation
Professional identity formation (PIF) is an integral part of educating professionals. A well-formed professional identity helps individuals to develop a meaningful professional self-understanding that facilitates their transition to and sustainability in professional work. Although professional identity and its formation are well theorized, it is largely unclear how the underpinning interpretive process of professional identity work leads to observable changes in thoughts, feelings and behaviours, and how these insights can be used in educational practice. To address this gap, we conducted an integrative review of 77 empirical articles on professional identity formation and inductively developed a four-fold typology of professional identity work, through which individuals reportedly make the shift from individual to professional. The theoretical contribution of this article is a more nuanced understanding of the practical manifestations of professional identity work. As a practical contribution, the typology may be used as a heuristic through which educators of professionals can support their students’ professional identity formation, particularly where this is halted or complicated by obstructions
Electrically charged fluids with pressure in Newtonian gravitation and general relativity in d spacetime dimensions: theorems and results for Weyl type systems
Previous theorems concerning Weyl type systems, including Majumdar-Papapetrou
systems, are generalized in two ways, namely, we take these theorems into d
spacetime dimensions (), and we also consider the very
interesting Weyl-Guilfoyle systems, i.e., general relativistic charged fluids
with nonzero pressure. In particular within Newton-Coulomb theory of charged
gravitating fluids, a theorem by Bonnor (1980) in three-dimensional space is
generalized to arbitrary space dimensions. Then, we prove a new
theorem for charged gravitating fluid systems in which we find the condition
that the charge density and the matter density should obey. Within general
relativity coupled to charged dust fluids, a theorem by De and Raychaudhuri
(1968) in four-dimensional spacetimes in rendered into arbitrary
dimensions. Then a theorem, new in and dimensions, for
Weyl-Guilfoyle systems, is stated and proved, in which we find the condition
that the charge density, the matter density, the pressure, and the
electromagnetic energy density should obey. This theorem comprises, as
particular cases, a theorem by Gautreau and Hoffman (1973) and results in four
dimensions by Guilfoyle (1999). Upon connection of an interior charged solution
to an exterior Tangherlini solution (i.e., a Reissner-Nordstr\"om solution in
d-dimensions), one is able to give a general definition for gravitational mass
for this kind of relativistic systems and find a mass relation with the several
quantities of the interior solution. It is also shown that for sources of
finite extent the mass is identical to the Tolman mass.Comment: 27 page
See a Black Hole on a Shoestring
The modes of vibration of hanging and partially supported strings provide
useful analogies to scalar fields travelling through spacetimes that admit
conformally flat spatial sections. This wide class of spacetimes includes
static, spherically symmetric spacetimes. The modes of a spacetime where the
scale factor depends as a power-law on one of the coordinates provide a useful
starting point and yield a new classification of these spacetimes on the basis
of the shape of the string analogue. The family of corresponding strings follow
a family of curves related to the cycloid, denoted here as hypercycloids (for
reasons that will become apparent). Like the spacetimes that they emulate these
strings exhibit horizons, typically at their bottommost points where the string
tension vanishes; therefore, hanging strings may provide a new avenue for the
exploration of the quantum mechanics of horizons.Comment: 5 pages, 1 figure, extensive changes to refect version accepted to
PR
Black string and velocity frame dragging
We investigate velocity frame dragging with the boosted Schwarzschild black
string solution and the boosted Kaluza-Klein bubble solution, in which a
translational symmetry along the boosted -coordinate is implemented. The
velocity frame dragging effect can be nullified by the motion of an observer
using the boost symmetry along the coordinate if it is not compact.
However, in spacetime with the compact coordinate, we show that the effect
cannot be removed since the compactification breaks the global Lorentz boost
symmetry. As a result, the comoving velocity is dependent on and the
momentum parameter along the coordinate becomes an observer independent
characteristic quantity of the black string and bubble solutions. The dragging
induces a spherical ergo-region around the black string.Comment: 8 pages, no figure, some correction
Quantum Corrections to the Reissner-Nordstrom and Kerr-Newman Metrics: Spin 1
A previous evaluation of one-photon loop corrections to the energy-momentum
tensor has been extended to particles with unit spin and speculations are
presented concerning general properties of such forms.Comment: 21 pages, 1 Figur
Classical and Quantum Analysis of Repulsive Singularities in Four Dimensional Extended Supergravity
Non--minimal repulsive singularities (``repulsons'') in extended supergravity
theories are investigated. The short distance antigravity properties of the
repulsons are tested at the classical and the quantum level by a scalar
test--particle. Using a partial wave expansion it is shown that the particle
gets totally reflected at the origin. A high frequency incoming particle
undergoes a phase shift of . However, the phase shift for a
low--frequency particle depends upon the physical data of the repulson. The
curvature singularity at a finite distance turns out to be transparent
for the scalar test--particle and the coordinate singularity at the origin
serves as a repulsive barrier at which particles bounce off.Comment: 20 pages, 14 figure
Cosmological Constant, Conical Defect and Classical Tests of General Relativity
We investigate the perihelion shift of the planetary motion and the bending
of starlight in the Schwarzschild field modified by the presence of a
-term plus a conical defect. This analysis generalizes an earlier
result obtained by Islam (Phys. Lett. A 97, 239, 1983) to the case of a pure
cosmological constant. By using the experimental data we obtain that the
parameter characterizing the conical defect is less than
and , respectively, on the length scales associated with such
phenomena. In particular, if the defect is generated by a cosmic string, these
values correspond to limits on the linear mass densities of and
, respectively.Comment: 9 pages, no figures, revte
Structure and deformation of the Kermadec forearc in response to subduction of the Pacific oceanic plate
The Tonga-Kermadec forearc is deforming in response to on-going subduction of the Pacific Plate beneath the Indo-Australian Plate. Previous research has focussed on the structural development of the forearc where large bathymetric features such as the Hikurangi Plateau and Louisville Ridge seamount chain are being subducted. Consequently, knowledge of the ‘background’ forearc in regions of normal plate convergence is limited. We report on an ∼250-km-long multichannel seismic reflection profile that was shot perpendicular to the Tonga-Kermadec trench at ∼28°S to determine the lateral and temporal variations in the structure, stratigraphy and deformation of the Kermadec forearc resulting solely from Pacific Plate subduction.
Interpretation of the seismic profile, in conjunction with regional swath bathymetry data, shows that the Pacific Plate exhibits horst and graben structures that accommodate bending-induced extensional stresses, generated as the trenchward dip of the crust increases. Trench infill is also much thicker than expected at 1 km which, we propose, results from increased sediment flux into and along the trench. Pervasive normal faulting of the mid-trench slope most likely accommodates the majority of the observed forearc extension in response to basal subduction erosion, and a structural high is located between the mid- and upper-trench slopes. We interpret this high as representing a dense and most likely structurally robust region of crust lying beneath this region.
Sediment of the upper-trench slope documents depositional hiatuses and on-going uplift of the arc. Strong along-arc currents appear to erode the Kermadec volcanic arc and distribute this sediment to the surrounding basins, while currents over the forearc redistribute deposits as sediment waves. Minor uplift of the transitional Kermadec forearc, observed just to the north of the profile, appears to relate to an underlying structural trend as well as subduction of the Louisville Ridge seamount chain 250 km to the north. Relative uplift of the Kermadec arc is observed from changes in the tilt of upper-trench slope deposits and extensional faulting of the basement immediately surrounding the Louisville Ridge
Re)seeing our teacher education practices through visual literacy. American Reading Forum Annual Yearbook
Abstract Guided by feminist communication theory and the transactional theory of learning, eight teacher educators used self-study methodology to critically "read" their teaching in light of the Common Core State Standards for visual literacy. Results demonstrated (1) visuals served as both objects and mediums; (2) teacher educators were part of the interpretive act of making meaning through visual texts; (3) in order to implement educational mandates, teacher educators needed time and space; and (4) the use of a collaborative conference protocol facilitated the teacher educators' ability to step back and re-see policy as a medium for transformation. Together they learned that while policy initiatives are likely not going away, educators can learn to change their response to mandates by becoming part of the interpretative act of implementing educational policy
Higher dimensional flat embeddings of (2+1) dimensional black holes
We obtain the higher dimensional global flat embeddings of static, rotating,
and charged BTZ black holes. On the other hand, we also study the similar
higher dimensional flat embeddings of the (2+1) de Sitter black holes which are
the counterparts of the anti-de Sitter BTZ black holes. As a result, the
charged dS black hole is shown to be embedded in (3+2) GEMS, contrast to the
charged BTZ one having (3+3) GEMS structure.Comment: 16pages, revtex, no figures, to appear in Phys. Rev.
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