1,706 research outputs found
Solution of the SU(N) Vertex Model with Non-Diagonal Open Boundaries
We diagonalize the double-row transfer matrix of the SU(N) vertex model for
certain classes of non-diagonal boundary conditions. We derive explicit
expressions for the corresponding eigenvectors and eigenvalues by means of the
algebraic Bethe ansatz approach.Comment: 10 page
The personal belief in a just world and domain-specific beliefs about justice at school and in the family: A longitudinal study with adolescents
This article investigates the relationship between the personal belief in a just world (BJW) and domain-specific beliefs about justice and examines how justice cognitions impact on adolescents' development, particularly on their achievement at school and their subjective well-being. A longitudinal questionnaire study with German adolescents aged 14-19 years was conducted over a period of five to eight months. The pattern of results revealed that evaluations of the school climate and of the family climate as being just were two distinct phenomena, both of which impacted on the personal BJW, which in turn affected the domain-specific beliefs about justice. However, the domain-specific beliefs about justice did not impact on each other directly. Moreover, an evaluation of the family climate (but not of the school climate) as being just reduced depressive symptoms, whereas depressive symptoms did not weaken the evaluation of one's family as being just. The evaluation of the school climate as being just improved the grades received in the next school report, whereas the grades received did not affect the justice evaluation of the school climate. Finally, all relationships persisted when controlling for age and gender. In sum, the pattern of findings supports the notion that justice cognitions impact on development during adolescence
Passenger transmission and productiveness of transit lines with high loads
Deterministic transit capacity analysis applies to planning, design and operational management of urban transit systems. The Transit Capacity and Quality of Service Manual (1) and Vuchic (2, 3) enable transit performance to be quantified and assessed using transit capacity and productive capacity. This paper further defines important productive performance measures of an individual transit service and transit line. Transit work (p-km) captures the transit task performed over distance. Passenger transmission (p-km/h) captures the passenger task delivered by service at speed. Transit productiveness (p-km/h) captures transit work performed over time. These measures are useful to operators in understanding their services’ or systems’ capabilities and passenger quality of service. This paper accounts for variability in utilized demand by passengers along a line and high passenger load conditions where passenger pass-up delay occurs. A hypothetical case study of an individual bus service’s operation demonstrates the usefulness of passenger transmission in comparing existing and growth scenarios. A hypothetical case study of a bus line’s operation during a peak hour window demonstrates the theory’s usefulness in examining the contribution of individual services to line productive performance. Scenarios may be assessed using this theory to benchmark or compare lines and segments, conditions, or consider improvements
ARCTIC: A Dataset for Dexterous Bimanual Hand-Object Manipulation
Humans intuitively understand that inanimate objects do not move by themselves, but that state changes are typically caused by human manipulation (e.g., the opening of a book). This is not yet the case for machines. In part this is because there exist no datasets with ground-truth 3D annotations for the study of physically consistent and synchronised motion of hands and articulated objects. To this end, we introduce ARCTIC -- a dataset of two hands that dexterously manipulate objects, containing 2.1M video frames paired with accurate 3D hand and object meshes and detailed, dynamic contact information. It contains bi-manual articulation of objects such as scissors or laptops, where hand poses and object states evolve jointly in time. We propose two novel articulated hand-object interaction tasks: (1) Consistent motion reconstruction: Given a monocular video, the goal is to reconstruct two hands and articulated objects in 3D, so that their motions are spatio-temporally consistent. (2) Interaction field estimation: Dense relative hand-object distances must be estimated from images. We introduce two baselines ArcticNet and InterField, respectively and evaluate them qualitatively and quantitatively on ARCTIC
Bethe ansatz for the XXX-S chain with non-diagonal open boundaries
We consider the algebraic Bethe ansatz solution of the integrable and
isotropic XXX-S Heisenberg chain with non-diagonal open boundaries. We show
that the corresponding K-matrices are similar to diagonal matrices with the
help of suitable transformations independent of the spectral parameter. When
the boundary parameters satisfy certain constraints we are able to formulate
the diagonalization of the associated double-row transfer matrix by means of
the quantum inverse scattering method. This allows us to derive explicit
expressions for the eigenvalues and the corresponding Bethe ansatz equations.
We also present evidences that the eigenvectors can be build up in terms of
multiparticle states for arbitrary S.Comment: 62 page
Multiaxial Kitagawa analysis of A356-T6
Experimental Kitagawa analysis has been performed on A356-T6 containing
natural and artificial defects. Results are obtained with a load ratio of R =
-1 for three different loadings: tension, torsion and combined tension-torsion.
The critical defect size determined is 400 \pm 100 \mum in A356-T6 under
multiaxial loading. Below this value, the microstructure governs the endurance
limit mainly through Secondary Dendrite Arm Spacing (SDAS). Four theoretical
approaches are used to simulate the endurance limit characterized by a Kitagawa
relationship are compared: Murakami relationships [Y Murakami, Metal Fatigue:
Effects of Small Defects and Nonmetallic Inclusions, Elsevier, 2002.],
defect-crack equivalency via Linear Elastic Fracture Mechanics (LEFM), the
Critical Distance Method (CDM) proposed by Susmel and Taylor [L. Susmel, D.
Taylor. Eng. Fract. Mech. 75 (2008) 15.] and the gradient approach proposed by
Nadot [Y. Nadot, T. ~Billaudeau. Eng. Fract. Mech. 73 (2006) 1.]. It is shown
that the CDM and gradient methods are accurate; however fatigue data for three
loading conditions is necessary to allow accurate identification of an
endurance limit.Comment: 27 pages, 11 figure
Solutions of the reflection equations for the vertex model
We investigate the possible regular solutions of the boundary Yang-Baxter
equation for the fundamental vertex model. We find four distinct
classes of reflection matrices such that half of them are diagonal while the
other half are non-diagonal. The latter are parameterized by two continuous
parameters but only one solution has all entries non-null. The non-diagonal
solutions do not reduce to diagonal ones at any special limit of the
free-parameters.Comment: 18 page
The spectrum of an open vertex model based on the U_q[SU(2)] at roots of unity
We study the exact solution of an -state vertex model based on the
representation of the algebra at roots of unity with diagonal open
boundaries. We find that the respective reflection equation provides us one
general class of diagonal -matrices having one free-parameter. We determine
the eigenvalues of the double-row transfer matrix and the respective Bethe
ansatz equation within the algebraic Bethe ansatz framework. The structure of
the Bethe ansatz equation combine a pseudomomenta function depending on a
free-parameter with scattering phase-shifts that are fixed by the roots of
unity and boundary variables.Comment: 21 page
3D MHD Flux Emergence Experiments: Idealized models and coronal interactions
This paper reviews some of the many 3D numerical experiments of the emergence
of magnetic fields from the solar interior and the subsequent interaction with
the pre-existing coronal magnetic field. The models described here are
idealized, in the sense that the internal energy equation only involves the
adiabatic, Ohmic and viscous shock heating terms. However, provided the main
aim is to investigate the dynamical evolution, this is adequate. Many
interesting observational phenomena are explained by these models in a
self-consistent manner.Comment: Review article, accepted for publication in Solar Physic
The angiotensin II type I receptor contributes to impaired cerebral blood flow autoregulation caused by placental ischemia in pregnant rats
BACKGROUND: Placental ischemia and hypertension, characteristic features of preeclampsia, are associated with impaired cerebral blood flow (CBF) autoregulation and cerebral edema. However, the factors that contribute to these cerebral abnormalities are not clear. Several lines of evidence suggest that angiotensin II can impact cerebrovascular function; however, the role of the renin angiotensin system in cerebrovascular function during placental ischemia has not been examined. We tested whether the angiotensin type 1 (AT1) receptor contributes to impaired CBF autoregulation in pregnant rats with placental ischemia caused by surgically reducing uterine perfusion pressure. METHODS: Placental ischemic or sham operated rats were treated with vehicle or losartan from gestational day (GD) 14 to 19 in the drinking water. On GD 19, we assessed CBF autoregulation in anesthetized rats using laser Doppler flowmetry. RESULTS: Placental ischemic rats had impaired CBF autoregulation that was attenuated by treatment with losartan. In addition, we examined whether an agonistic autoantibody to the AT1 receptor (AT1-AA), reported to be present in preeclamptic women, contributes to impaired CBF autoregulation. Purified rat AT1-AA or vehicle was infused into pregnant rats from GD 12 to 19 via mini-osmotic pumps after which CBF autoregulation was assessed. AT1-AA infusion impaired CBF autoregulation but did not affect brain water content. CONCLUSIONS: These results suggest that the impaired CBF autoregulation associated with placental ischemia is due, at least in part, to activation of the AT1 receptor and that the RAS may interact with other placental factors to promote cerebrovascular changes common to preeclampsia
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