Wall Junction Research Articles

Vibration transmission between coupled plates using finite element methods and statistical energy analysis. Part 1: Comparison of measured and predicted data for masonry walls with and without apertures

In Part 1 of this paper a study is made to assess the prediction of vibration transmission between masonry walls using Finite Element Methods (FEM) and Statistical Energy Analysis (SEA) through a comparison of measured and predicted data. Masonry walls typically have low modal overlap and low modal density at low frequencies, hence FEM is used to predict the large fluctuations in the vibration level difference. The issue of uncertainty in the physical description of masonry walls is addressed by using Monte Carlo methods with FEM. Two types of masonry wall junction are studied, an L-junction and a T-junction. The importance of in-plane wave transmission was demonstrated for L-junctions with apertures and T-junctions. The agreement between FEM, SEA and measured data at high frequencies indicated that the conversion between bending and in-plane waves in the FEM models was correct.

Clinicopathological characteristics of 10 patients with rupture of both ventricular free wall and septum (double rupture) after acute myocardial infarction.

Cardiac ruptures after myocardial infarction are classified as ventricular free wall ruptures (FWR), ventricular septal ruptures (VSR), and papillary muscle ruptures (PMR). A combination of any two types of rupture is called "ventricular double rupture;" (VDR) and shows a specific clinical course. 3,284 patients with acute myocardial infarction (AMI) were admitted to the CCU of our hospital between April, 1973 and December, 2001, and 10 patients (8 males and 2 female, aged 54 through 82 years) with VDR were clinicopathologically evaluated. All were diagnosed as VDR consisting of FWR and VSR. VDR was observed in 0.30% of all patients with AMI, in 3.0% of those with FWR, and in 16.1% of those with VSR. The infarct site was anteroseptal in 3 patients, anterolateral in 3, inferior in 3, and posterolateral in 1. Two patients with inferior infarction complicated RV infarction and a patient with posterolateral infarction had healed inferior infarction. The risk factors related to VDR were age, a history of hypertension, increased sympathetic tone to improve hemodynamic aggravation after perforation, cardiotonic agents, thrombolytic agents, delayed reperfusion, right ventricular volume overload by shunt and re-infarction. However, these factors might have played only a subsidiary role. The most important factor in VDR was the pathological findings. The site of septal perforation was the apex close to the septum-free wall junction in 9 patients and the site of rupture was also apical in 8 patients. Four patients already had VSR on admission to our CCU. FWR developed soon after VSR was demonstrated in 4 patients. FWR and VSR occurred simultaneously in one patient. These results suggest that VSR in the apical region is a precursor of VDR and requires the earliest surgical treatment. Surgical treatment was carried out in the operating room in 5 patients and 3 (60.0%) of them survived for 4 months or more. Two patients with rupture incidentally detected during operation for VSR were discharged and are still alive, though another one with free wall blow out rupture died 129 days after operation. Bedside thracotomy was performed in 3 patients and all of them died.

Clash of symmetries on the brane

If our $(3+1)$-dimensional universe is a brane or domain wall embedded in a higher dimensional space, then a phenomenon we term the ``clash of symmetries'' provides a new method of breaking some continuous symmetries. A global ${G}_{\mathrm{cts}}\ensuremath{\bigotimes}{G}_{\mathrm{discrete}}$ symmetry is spontaneously broken to ${H}_{\mathrm{cts}}\ensuremath{\bigotimes}{H}_{\mathrm{discrete}},$ where the continuous subgroup ${H}_{\mathrm{cts}}$ can be embedded in several different ways in the parent group ${G}_{\mathrm{cts}},$ and ${H}_{\mathrm{discrete}}<{G}_{\mathrm{discrete}}.$ A certain class of topological domain wall solutions connects two vacua that are invariant under differently embedded ${H}_{\mathrm{cts}}$ subgroups. There is then enhanced symmetry breakdown to the intersection of these two subgroups on the domain wall. This is the ``clash.'' In the brane limit, we obtain a configuration with ${H}_{\mathrm{cts}}$ symmetries in the bulk but the smaller intersection symmetry on the brane itself. We illustrate this idea using a permutation symmetric three-Higgs-triplet toy model exploiting the distinct $I\ensuremath{-},$ $U\ensuremath{-}$ and $V\ensuremath{-}\mathrm{spin}$ U(2) subgroups of U(3). The three disconnected portions of the vacuum manifold can be treated symmetrically through the construction of a threefold planar domain wall junction configuration, with our universe at the nexus. A possible connection with ${E}_{6}$ is discussed.

Real-time 3-dimensional echocardiography imaging for right ventricular endomyocardial biopsy: A comparison with fluoroscopy

Real-time 3-dimensional (RT3D) echocardiography has the potential to precisely identify the position of an object in 3-dimensional space. Therefore, we hypothesized that RT3D echocardiography could rapidly facilitate accurate placement of a bioptome within the right ventricle and may offer advantages over a fluoroscopically guided approach. During 63 routine right ventricular biopsy procedures (total of 315 biopsy attempts) in 33 cardiac allograft recipients, the bioptome was initially guided against the intraventricular septum with the use of biplane fluoroscopy. Bioptome position was then evaluated by RT3D echocardiography by using the Volumetrics Model 1 with the transducer placed at the apex. Multiple long-axis and short-axis planes were simultaneously visualized and customized to identify the tip of the bioptome. Bioptome placement was prospectively classified as septal, free wall/septal junction, or free wall. Of the 36 patients studied, 33 (91%) had adequate RT3D images. Of 315 bioptome placements visualized by RT3D echocardiography after fluoroscopic placement, bioptome position against the septum was confirmed in 113 (36%), against the septal/free wall (anterior or posterior) junction in 140 (44%), against the free wall in 60 (19%), and in the coronary sinus in 2 (1%). RT3D echocardiography is readily feasible for use in the majority of transplant patients undergoing right ventricular endomyocardial biopsy. Visualization of the bioptome in multiple simultaneous planes allows accurate localization of the biopsy site. The potential for improved localization of the bioptome tip in the right ventricle may have important clinical implications for augmenting the efficacy of this procedure. (J Am Soc Echocardiogr 2001;14:927-33.)

An exact solution of BPS junctions and its properties

We have obtained an exact solution for the BPS domain wall junction for a N = 1 supersymmetric theory in four dimensions and studied its properties. The model is a simplified version of the ¢N = 2 SU(2) gauge theory with N f = 1 broken to N = 1 by the mass of the adjoint chiral superfield. We define mode equations and demonstrate explicitly that fermion and boson with the same mass have to come in pairs except massless modes. We work out explicitly massless Nambu-Goldstone (NG) modes on the BPS domain wall junction. We find that their wave functions extend along the wall to infinity (not localized) and are not normalizable. It is argued that this feature is a generic phenomenon of NG modes on domain wall junctions in the bulk flat space in any dimensions. NG fermions exhibit a chiral structure in accordance with unitary representations of (1, 0) supersymmetry algebra where fermion and boson with the same mass come in pairs except massless modes which can appear singly. More detailed exposition of our results can be found in Refs. [1], [2].

A comparison of the mechanical behavior of posterior teeth with amalgam and composite MOD restorations

Objective: To compare the mechanical behavior, and infer differences in fracture resistance, of mandibular molars with amalgam and composite MOD restorations to that of an unrestored molar. Method: Finite element models were developed for an unrestored molar and molars with MOD amalgam and composite restorations. The location and magnitude of maximum principal stress resulting from simultaneous mechanical and thermal loads were determined for each molar using a series of designed experiments. An analysis of variance was conducted with the components of stress to distinguish the relative influence of oral parameters and restoration on the stress distribution in each molar. Results: The maximum principal stress in the unrestored molar was the largest of all three molars examined and occurred within the dentin along the pulpal wall. Maximum principal stresses in the molars with amalgam and composite restorations both occurred along the cavosurface margin. Maximum principal stresses in the molar with amalgam restoration occurred at the pulpal floor and lingual wall junction and resulted from large occlusal loads. Although occlusal loading had minimal effects on the stress distribution within the molar with composite restoration, low oral temperatures were responsible for the maximum principal stresses, which were found at the lingual margin and occlusal surface junction. Conclusion: There was no significant difference in the magnitude of maximum stress that occurred in the molars with amalgam and light curing composite restorations. However, the location and orientation of maximum stress in the restored molars were largely dependent on the restorative material. Although clinical studies report that tooth fracture occurs predominately to restored molars, the unrestored molar experienced the highest stress in this investigation. Therefore, the reduction in fracture resistance of restored posterior teeth appears to result from changes in the location of maximum stress resulting from mastication and temperature changes.

Leaving the BPS bound: Tunneling of classically saturated solitons

We discuss quantum tunneling between classically BPS saturated solitons in two-dimensional theories with N=2 supersymmetry and a compact space dimension. Genuine BPS states form shortened multiplets of dimension two. In the models we consider there are two degenerate shortened multiplets at the classical level, but there is no obstruction to pairing up through quantum tunneling. The tunneling amplitude in the imaginary time is described by instantons. We find that the instanton is nothing but the 1/4 BPS saturated ``wall junction,'' considered previously in the literature in other contexts. Two central charges of the superalgebra allow us to calculate the instanton action without finding the explicit solution (it is checked, though, numerically, that the saturated solution does exist). We present a quantum-mechanical interpretation of the soliton tunneling.

Gravity localization with a domain wall junction in six dimensions

We study gravity localization in the context of a six-dimensional gravity model coupled with complex scalar fields. With a supergravity-motivated scalar potential, we show that the domain wall junction solutions localize a four-dimensional massless graviton under an assumption on the wall profile. We find that unlike the global supersymmetric model, contributions to the junction tension cancel locally with gravitational contributions. The wall tension vanishes due to the metric suppression.

Nonnormalizable zero modes on BPS junctions

Using an exact solution as a concrete example, Nambu-Goldstone modes on the BPS domain wall junction are worked out for N=1 supersymmetric theories in four dimensions. Their wave functions extend along the wall to infinity (not localized) and are not normalizable. It is argued that this feature is a generic phenomenon of Nambu-Goldstone modes on domain wall junctions in the bulk flat space in any dimensions. We formulate mode equations and show that fermion and boson with the same mass come in pairs except massless modes which can appear singly, in accordance with unitary representations of (1, 0) supersymmetry.

Maintenance Claw Trimming in Cattle with Special Emphasis on the Dutch Method

Application of the Dutch claw trimming method requires understanding of horn structure and function including growth and wear as well as the biomechanics of weight bearing. The shape and weight bearing surface of normal claws can be described as follows: The normal weight bearing area of the claw includes the heel, wall, and the white line as well as the sole.6 It is important to note that the abaxial wall is weight bearing along its entire length from the abaxial heel wall junction to the toe.6 The axial wall and white line is only weight bearing for a short distance up to a point where they diverge proximally in the interdigital space.6 The sole is weight bearing along its entire surface except at its innermost portion directly adjacent to the interdigital space. Here the sole is sloped for approximately one-third of the width of the sole in that area.6

Domain wall junctions in supersymmetric field theories in D = 4

We study the possible BPS domain wall junction configurations for general polynomial superpotentials of N=1 supersymmetric Wess-Zumino models in D=4. We scan the parameter space of the superpotential and find different possible BPS states for different values of the deformation parameters and present our results graphically. We comment on the domain walls in F/M/IIA theories obtained from the Calabi-Yau fourfolds with isolated singularities and a background flux.

Dwalls and junctions in supersymmetric gluodynamics in the largeNlimit suggest the existence of heavy hadrons

A number of arguments exists that the ``minimal'' Bogomol'nyi-Prasad-Sommerfeld (BPS) wall width in large-$N$ supersymmetric gluodynamics vanishes as $1/N.$ There is a certain tension between this assertion and the fact that the mesons coupled to $\ensuremath{\lambda}\ensuremath{\lambda}$ have masses $\mathcal{O}{(N}^{0}).$ To reconcile these facts we argue that there should exist additional solitonlike states with masses scaling as N. The BPS walls must be ``made'' predominantly of these heavy states which are coupled to $\ensuremath{\lambda}\ensuremath{\lambda}$ stronger than the conventional mesons. The tension of the BPS wall junction scales as ${N}^{2},$ which serves as an additional argument in favor of the $1/N$ scaling of the wall width. The heavy states can be thought of as solitons of the corresponding closed string theory. They are related to certain fivebranes in the M-theory construction. We study the issue of the wall width in toy models which capture some features of supersymmetric gluodynamics. We speculate that the special hadrons with mass scaling as N should also exist in the large-$N$ limit of nonsupersymmetric gluodynamics.

Modeling a network of brane worlds

We study junctions of supersymmetric domain walls in N=1 supergravity theories in four dimensions, coupled to a chiral superfield with quartic superpotential having $Z_3$ symmetry. After deriving a BPS equation of the domain wall junction, we consider a stable hexagonal configuration of network of brane junctions, which are only approximately locally BPS. We propose a model for a mechanism of supersymmetry breaking without loss of stability, where a messenger for the SUSY breaking comes from the neighboring anti-BPS junction world, propagating along the domain walls connection them.

An exact solution of BPS domain wall junction

An exact solution of domain wall junction is obtained in a four-dimensional N=1 supersymmetric U(1)× U(1)′ gauge theory with three pairs of chiral superfields which is motivated by the N=2 SU(2) gauge theory with one flavor perturbed by an adjoint scalar mass. The solution allows us to evaluate various quantities including a new central charge Y k associated with the junction besides Z k which appears already in domain walls. We find that the new central charge Y k gives a negative contribution to the mass of the domain wall junction whereas the central charge Z k gives a dominant positive contribution. One has to be cautious to identify the central charge Y k alone as the mass of the junction.

Magnetic behavior and resistivity of the domain-wall junction GdFe(1000 Å)/TbFe/GdFe(500 Å)

A GdFe/TbFe/GdFe trilayer constitutes a magnetic nanostructure: the domain wall junction. With this device, we studied the propagation of 180\ifmmode^\circ\else\textdegree\fi{} domain walls from one GdFe layer to the other, through a single planar defect (the thin TbFe layer) that acts as an artificial energy barrier. Before crossing the energy barrier, by thermal activation, due to the applied magnetic field, the domain walls are compressed against the TbFe layer. Nucleation, compression, and propagation phenomena of 180\ifmmode^\circ\else\textdegree\fi{} domain walls are presented. The behavior of domain walls is followed from the electrical resistivity of the sample. A parallel between the domain-wall decompression and the exchange biasing problem in ferromagnetic/antiferromagnetic bilayers is proposed.

Space–Time Defects: Torsion Walls

The geometry of torsion defects in Weitzenböck space–time is investigated. Conformal de Sitter space–time outside the defect is obtained. Geodesic motion of test particles outside the torsion wall is given. Torsion defect wall is shown to have repulsive gravitational fields. Static torsion defect is obtained by gluing together two half Minkowski spaces across a torsion wall junction.

Quantum tunneling effect in magnetic particles

During the past five yeas, researchers have achieved advances in both sample elaboration and measurement techniques in an effort to witness macroscopic quantum tunneling of magnetization. Important advances include experimental results of relaxation measurements, single particle measurements, and domain wall junction, quantum coherence and quantum resonance measurements. Quantum resonance measurements have shown unambiguously quantum tunneling of magnetization at a scale of one nanometer.

Unusual slow magnetic relaxation on a SmCo 2/GdCo 2 domain wall junction at low temperature

The slow dynamics of the magnetization of a domain wall junction (ferromagnetic layers separated by an artificial planar barrier) has been studied through after-effect measurements. We show that two different dynamical magnetic processes take place at low temperature. The time and the thermal dependences of the magnetization suggest that a simple interpretation in terms of thermal activated processes is not always valid. An interpretation in terms of linear response to a local field is proposed.

123I-BMIPP SPECT imaging in hyertrophic cardiomyopathy in reference to septal-free wall junction of left ventricle

123I-BMIPP SPECT imaging in hyertrophic cardiomyopathy in reference to septal-free wall junction of left ventricle

Numerical calculation of a domain wall junction

Numerical calculations of a rigid Bloch wall junction performed for various thickness of the central pinning layer show the existence of three states minimizing the energy of the system, as expected in a theoretical approach.