14,218 research outputs found
Body image perception and body composition: assessment of perception inconsistency by a new index
BACKGROUND: A correct perception of the body image, as defined by comparison with actual anthropometric analyses, is crucial to ensure the best possible nutritional status of each individual. Bioimpedance analysis (BIA) represents a leading technique to assess body composition parameters and, in particular, the fat mass. This study examined the self-perception of body image at various levels of adiposity proposing a new index. METHODS: We investigated 487 young Italian adults (mean age of males: 21.9 ± 2.4 years; mean age of females: 21.0 ± 2.2 years). Each subject could choose, on the Contour Drawing Rating Scale, the silhouette that he/she considered most resembling his/her perceived body image as well as his/her ideal body image. On each subject, we performed anthropometric measurements and determined the values of Fat mass and út with BIA. A new index, FAIFAT (Feel fat status minus Actual fat status Inconsistency), was developed to evaluate possible fat status perception inconsistencies by BIA. RESULTS: Based on ideal and feel body image comparison, women showed higher dissatisfaction than men and preferred slimmer silhouettes. FAIFAT values indicated that the fat status perception was correct in the majority of the examined individuals and only three subjects showed a serious misperception. CONCLUSIONS: Our findings suggest that FAIFAT is an appropriate index for assessing the perceived fat status from the body image when compared with data obtained by BIA. In a population, the use of this index will allow the correct identification of groups at risk for eating disorders
On the normalization of Killing vectors and energy conservation in two-dimensional gravity
We explicitly show that, in the context of a recently proposed 2D dilaton
gravity theory, energy conservation requires the ``natural'' Killing vector to
have, asymptotically, an unusual normalization. The Hawking temperature
is then calculated according to this prescription.Comment: 7 pages, Latex, no figure
A note on the Schur multiplier of a nilpotent Lie algebra
For a nilpotent Lie algebra of dimension and dim, we find
the upper bound dim, where denotes the
Schur multiplier of . In case the equality holds if and only if
, where is an abelian Lie algebra of dimension
and H(1) is the Heisenberg algebra of dimension 3.Comment: Paper in press in Comm. Algebra with small revision
Connection between slow and fast dynamics of molecular liquids around the glass transition
The mean-square displacement (MSD) was measured by neutron scattering at
various temperatures and pressures for a number of molecular glass-forming
liquids. The MSD is invariant along the glass-transition line at the pressure
studied, thus establishing an ``intrinsic'' Lindemann criterion for any given
liquid. A one-to-one connection between the MSD's temperature dependence and
the liquid's fragility is found when the MSD is evaluated on a time scale of
approximately 4 nanoseconds, but does not hold when the MSD is evaluated at
shorter times. The findings are discussed in terms of the elastic model and the
role of relaxations, and the correlations between slow and fast dynamics are
addressed.Comment: accepted by Phys Rev E (2010
Mass corrections in string theory and lattice field theory
Kaluza-Klein compactifications of higher dimensional Yang-Mills theories
contain a number of four dimensional scalars corresponding to the internal
components of the gauge field. While at tree-level the scalar zero modes are
massless, it is well known that quantum corrections make them massive. We
compute these radiative corrections at 1-loop in an effective field theory
framework, using the background field method and proper Schwinger-time
regularization. In order to clarify the proper treatment of the sum over
KK--modes in the effective field theory approach, we consider the same problem
in two different UV completions of Yang-Mills: string theory and lattice field
theory. In both cases, when the compactification radius is much bigger than
the scale of the UV completion (), we recover a mass
renormalization that is independent of the UV scale and agrees with the one
derived in the effective field theory approach. These results support the idea
that the value of the mass corrections is, in this regime, universal for any UV
completion that respects locality and gauge invariance. The string analysis
suggests that this property holds also at higher loops. The lattice analysis
suggests that the mass of the adjoint scalars appearing in
Super Yang-Mills is highly suppressed due to an interplay between the
higher-dimensional gauge invariance and the degeneracy of bosonic and fermionic
degrees of freedom.Comment: 27 page
Dilaton Quantum Cosmology in Two Dimensions
We consider a renormalizable two-dimensional model of dilaton gravity coupled
to a set of conformal fields as a toy model for quantum cosmology. We discuss
the cosmological solutions of the model and study the effect of including the
backreaction due to quantum corrections. As a result, when the matter density
is below some threshold new singularities form in a weak coupling region, which
suggests that they will not be removed in the full quantum theory. We also
solve the Wheeler-DeWitt equation. Depending on the quantum state of the
Universe, the singularities may appear in a quantum region where the wave
function is not oscillatory, i.e., when there is not a well defined notion of
classical spacetime.Comment: 17 pages, UTTG-28-9
Soluble models in 2d dilaton gravity
A one-parameter class of simple models of two-dimensional dilaton gravity,
which can be exactly solved including back-reaction effects, is investigated at
both classical and quantum levels. This family contains the RST model as a
special case, and it continuously interpolates between models having a flat
(Rindler) geometry and a constant curvature metric with a non-trivial dilaton
field. The processes of formation of black hole singularities from collapsing
matter and Hawking evaporation are considered in detail. Various physical
aspects of these geometries are discussed, including the cosmological
interpretation.Comment: 15 pages, harvmac, 3 figure
The low energy expansion of the one-loop type II superstring amplitude
The one-loop four-graviton amplitude in either of the type II superstring
theories is expanded in powers of the external momenta up to and including
terms of order s^4 log s R^4, where R^4 denotes a specific contraction of four
linearized Weyl tensors and s is a Mandelstam invariant. Terms in this series
are obtained by integrating powers of the two-dimensional scalar field theory
propagator over the toroidal world-sheet as well as the moduli of the torus.
The values of these coefficients match expectations based on duality relations
between string theory and eleven-dimensional supergravity.Comment: harvmac (b), 25 pages, 3 eps figures. v2: Factors of 2 corrected.
Conclusion unchange
Restructuring requirements specifications for managing inconsistency and change: a case study
This paper describes our experiences in restructuring multi-perspective requirements specifications in order to identify and analyse inconsistencies and manage change. A partial, heterogeneous and reasonably large requirements specification from a NASA project was analysed and decomposed into a structure of "viewpoints", where each viewpoint encapsulates partial requirements of some system components described in the specification. Relationships between viewpoints were identified which included not only the interactions explicitly stated in the requirements but also some implicit and potentially problematic inter-dependencies. The restructuring process and a first informal analysis of the resulting relationships enabled the detection of inconsistencies and the definition of some interesting domain-dependent consistency rules. We believe that this restructuring into viewpoints also facilitated requirements understanding through partitioning, and requirements maintenance and evolution through explicit identification of the inter-viewpoint relationships
Análisis comparativo entre un tutor circular y uno monolateral en elongaciones óseas
El presente trabajo compara la funcionalidad de dos tutores externos utilizados
para elongación: el del Dr. Ilizarov y el tutor HG, desarrollado en nuestra institución. De 131
pacientes tratados con elongación ósea en 147 huesos largos se seleccionaron al azar 25 huesos
por cada aparato anteriormente mencionado. Para objetivar los resultados se registraron
estadÃsticamente variables independientes y dependientes en sus caracterÃsticas subjetivas y objetivas,
tales como: edad, sexo, tipo de hueso elongado, tolerancia psÃquica, sensación de confort,
facilidad de higiene y control, las infecciones, las rigideces articulares por retracción
músculo tendinosa, y la deformación ósea residual. El objetivo fue comparar y establecer si el
cambio en la elección del sistema fue ventajoso para nuestros pacientes. En el intento comparativo
se enfrentaron dos variables, que a nuestro criterio eran las más importantes para establecer
diferencias: la calidad del callo del hueso sometido a elongación y la presencia de
complicaciones tanto transitorias como definitivas.In this work we compare the results obtained with two different external fixation
devices in patients undergoing bone lengthening. The devices studied were the Ilizarov type
and the HG, an apparatons developed in our institution. Out of 131 patientes treated by
bone lengthening in 147 long bones, 25 bones lengthened with each device were selected at
random. Different subjective and objective variables were assessed: age, sex, type of bone, psichological
tolerance, patients, confort, nursing, infections, joint stiffness due to musculotendinous
retractions, and residual bone deformity. The aim of the study was to analyze if the
monolateral frame entailed advantages for our patients. Two main factors were more deeply
analysed, namely the quality of the bone callus subjected to lengthening and the presence of
both transitory and definitive complications
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