484 research outputs found
Beings in their own right? Exploring Children and young people's sibling and twin relationships in the Minority World
This paper examines the contributions that the sociological study of sibship and twinship in the Minority World can make to childhood studies. It argues that, in providing one forum within which to explore children and young people's social relationships, we can add to our understanding of children and young people's interdependence and develop a more nuanced understanding of agency. As emergent subjects, children, young people and adults are in a process of âbecomingâ. However, this does not mean that they can âbecomeâ anything they choose to. The notion of negotiated interdependence (Punch 2002) is useful in helping us to grasp the contingent nature of children and young people's agency
Public College Enrollment in Minnesota's Changing Population Pattern 1970-85.
Statewide trends from 1970 to 1985 in the number of high school graduates, college age population, and enrollment in colleges or vocational schools are examined along with the geographical variations across the state. These data are used to project enrollment figures for public colleges in 1975, 1980, and 1985
Holographic Conformal Window - A Bottom Up Approach
We propose a five-dimensional framework for modeling the background geometry
associated to ordinary Yang-Mills (YM) as well as to nonsupersymmetric gauge
theories possessing an infrared fixed point with fermions in various
representations of the underlying gauge group. The model is based on the
improved holographic approach, on the string theory side, and on the
conjectured all-orders beta function for the gauge theory one. We first analyze
the YM gauge theory. We then investigate the effects of adding flavors and show
that, in the holographic description of the conformal window, the geometry
becomes AdS when approaching the ultraviolet and the infrared regimes. As the
number of flavors increases within the conformal window we observe that the
geometry becomes more and more of AdS type over the entire energy range.Comment: 20 Pages, 3 Figures. v2: references adde
Quantum Hall Effect in a Holographic Model
We consider a holographic description of a system of strongly coupled
fermions in 2+1 dimensions based on a D7-brane probe in the background of
D3-branes, and construct stable embeddings by turning on worldvolume fluxes. We
study the system at finite temperature and charge density, and in the presence
of a background magnetic field. We show that Minkowski-like embeddings that
terminate above the horizon describe a family of quantum Hall states with
filling fractions that are parameterized by a single discrete parameter. The
quantization of the Hall conductivity is a direct consequence of the
topological quantization of the fluxes. When the magnetic field is varied
relative to the charge density away from these discrete filling fractions, the
embeddings deform continuously into black-hole-like embeddings that enter the
horizon and that describe metallic states. We also study the thermodynamics of
this system and show that there is a first order phase transition at a critical
temperature from the quantum Hall state to the metallic state.Comment: v2: 27 pages, 12 figures. There is a major revision in the
quantitative analysis. The qualitative results and conclusions are unchanged,
with one exception: we show that the quantum Hall state embeddings, which
exist for discrete values of the filling fraction, deform continuously into
metallic state embeddings away from these filling fraction
RG flow of transport quantities
The RG flow equation of various transport quantities are studied in arbitrary
spacetime dimensions, in the fixed as well as fluctuating background geometry
both for the Maxwellian and DBI type of actions. The regularity condition on
the flow equation of the conductivity at the horizon for the DBI action
reproduces naturally the leading order result of {\it Hartnoll et al.}, [{\it
JHEP}, {\bf 04}, 120 (2010)]. Motivated by the result of {\it van der Marel et
al.}, [{\it science}, {\bf 425}, 271 (2003], we studied, analytically, the
conductivity versus frequency plane by dividing it into three distinct parts:
and . In order to compare, we choose 3+1
dimensional bulk spacetime for the computation of the conductivity. In the
range, the conductivity does not show up the Drude like form in any
spacetime dimensions. In the range and staying away from the
horizon, for the DBI action with unit dynamical exponent, non-zero magnetic
field and charge density, the conductivity goes as , whereas the
phase of the conductivity, goes as,
and . There exists a universal
quantity at the horizon that is the phase angle of conductivity, which either
vanishes or an integral multiple of . Furthermore, we calculate the
temperature dependence to the thermoelectric and the thermal conductivity at
the horizon. The charge diffusion constant for the DBI action is studied.Comment: 1+68 pages, 12 figures and 4 appendices; V2: The charge diffusion
constant is calculated for arbitrary spacetime dimensions and related
references added; v3: Connection with the RG flow of 1010.4036 is made; v4:
Several corrections, typos fixed and a ref. adde
Sum rules, plasma frequencies and Hall phenomenology in holographic plasmas
We study the AC optical and hall conductivities of Dp/Dq-branes intersections
in the probe approximation and use sum-rules to study various associated
transport coefficients. We determine that the presence of massive fundamental
matter, as compared to massless fundamental matter described holographically by
a theory with no dimensional defects, reduces the plasma frequency. We further
show that this is not the case when the brane intersections include defects. We
discuss in detail how to implement correctly the regularization of retarded
Green's functions so that the dispersion relations are satisfied and the low
energy behaviour of the system is physically realistic.Comment: 25 pages, 5 figures. v2.minor changes, published versio
Love, rights and solidarity: studying children's participation using Honneth's theory of recognition
Recent attempts to theorize childrenâs participation have drawn on a wide range of ideas, concepts and models from political and social theory. The aim of this article is to explore the specific usefulness of Honnethâs theory of a âstruggle for recognitionâ in thinking about this area of practice. The article identifies what is distinctive about Honnethâs theory of recognition, and how it differs from other theories of recognition. It then considers the relevance of Honnethâs conceptual framework to the social position of children, including those who may be involved in a variety of âparticipatoryâ activities.
It looks at how useful Honnethâs ideas are in direct engagement with young peopleâs praxis, drawing on ethnographic research with members of a children and young peopleâs forum. The article concludes by reflecting on the implications of this theoretical approach and the further questions which it opens up for theories of participation and of adultâchild relations more generally
Improved Holographic QCD
We provide a review to holographic models based on Einstein-dilaton gravity
with a potential in 5 dimensions. Such theories, for a judicious choice of
potential are very close to the physics of large-N YM theory both at zero and
finite temperature. The zero temperature glueball spectra as well as their
finite temperature thermodynamic functions compare well with lattice data. The
model can be used to calculate transport coefficients, like bulk viscosity, the
drag force and jet quenching parameters, relevant for the physics of the
Quark-Gluon Plasma.Comment: LatEX, 65 pages, 28 figures, 9 Tables. Based on lectures given at
several Schools. To appear in the proceedinds of the 5th Aegean School
(Milos, Greece
Thermodynamics of SU(N) Yang-Mills theories in 2+1 dimensions II - The deconfined phase
We present a non-perturbative study of the equation of state in the
deconfined phase of Yang-Mills theories in D=2+1 dimensions. We introduce a
holographic model, based on the improved holographic QCD model, from which we
derive a non-trivial relation between the order of the deconfinement phase
transition and the behavior of the trace of the energy-momentum tensor as a
function of the temperature T. We compare the theoretical predictions of this
holographic model with a new set of high-precision numerical results from
lattice simulations of SU(N) theories with N=2, 3, 4, 5 and 6 colors. The
latter reveal that, similarly to the D=3+1 case, the bulk equilibrium
thermodynamic quantities (pressure, trace of the energy-momentum tensor, energy
density and entropy density) exhibit nearly perfect proportionality to the
number of gluons, and can be successfully compared with the holographic
predictions in a broad range of temperatures. Finally, we also show that, again
similarly to the D=3+1 case, the trace of the energy-momentum tensor appears to
be proportional to T^2 in a wide temperature range, starting from approximately
1.2 T_c, where T_c denotes the critical deconfinement temperature.Comment: 2+36 pages, 10 figures; v2: comments added, curves showing the
holographic predictions included in the plots of the pressure and energy and
entropy densities, typos corrected: version published in JHE
Thermodynamics of AdS5 black holes: holographic QCD and StĂŒckelberg model
Part of this work is based on Ref. [15], co-authored with Manuel Valle. I would like to thank him for collaboration and enlightening discussions. This research has been supported by Spanish MINEICO and European FEDER funds (Grant No. FIS2017-85053-C2-1-P), Plan Nacional de Altas Energas Spanish MINECO (Grant No. FPA2015-64041-C2-1-P), Junta de Andaluca (Grant No. FQM-225), Basque Government (Grant No. IT979-16), and ConsejerĂa de Conocimiento, Investigacion y Universidad of the Junta de AndalucĂa and European Regional Development Fund (ERDF) (Grant No. SOMM17/6105/UGR), as well as by Spanish MINECO Ramon y Cajal Program (Grant No. RYC-2016-20678), and by Universidad del Pas Vasco UPV/EHU, Bilbao, Spain, through a Visiting Professor appointment.We explore the thermodynamics of AdS(5) black holes in two models: i) an improved holographic QCD model with a simple dilaton potential, and ii) the Stuckelberg model in 5D. In the former case, by applying techniques of singular perturbation theory, we obtain a resummation of the naive expansion at high temperatures, providing a good fit to the lattice data for the trace anomaly. In the latter, we find a solution of the equations of motion by considering an expansion in the conformal dimension of the current associated to the gauge field.Spanish MINECO
FIS2017-85053-C2-1-PEuropean Union (EU)
FIS2017-85053-C2-1-PPlan Nacional de Altas Energas Spanish MINECO
FPA2015-64041-C2-1-PJunta de Andalucia
FQM-225Basque Government
IT979-16ConsejerĂa de Conocimiento, Investigacion y Universidad of the Junta de AndalucĂa SOMM17/6105/UGREuropean Union (EU)
SOMM17/6105/UGRSpanish MINECO Ramon y Cajal Program
RYC-2016-20678Universidad del Pas Vasco UPV/EHU, Bilbao, Spai
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