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We show that every compact, unitary two-dimensional CFT with an abelian conserved current has vanishing twist gap for charged primary fields with respect to the $\mathfrak{u}(1)\times$Virasoro algebra. This means that either the chiral algebra is enhanced by a charged primary field with zero twist or there is an infinite family of charged primary fields that accumulate to zero twist., Comment: 16 pages, 2 figures, v2: minor changes

We discuss symmetry fractionalization of the Lorentz group in (2+1)$d$ non-spin quantum field theory (QFT), and its implications for dualities. We prove that two inequivalent non-spin QFTs are dual as spin QFTs if and only if they are related by a Lorentz symmetry fractionalization with respect to an anomalous $\mathbb{Z}_2$ one-form symmetry. Moreover, if the framing anomalies of two non-spin QFTs differ by a multiple of 8, then they are dual as spin QFTs if and only if they are also dual as non-spin QFTs. Applications to summing over the spin structures, time-reversal symmetry, and level/rank dualities are explored. The Lorentz symmetry fractionalization naturally arises in Chern-Simons matter dualities that obey certain spin/charge relations, and is instrumental for the dualities to hold when viewed as non-spin theories., 29 pages, 3 figures. v2 appendix added and section 4.2 expanded

Following our earlier analyses of nonstandard continuum quantum field theories, we study here gapped systems in 3+1 dimensions, which exhibit fractonic behavior. In particular, we present three dual field theory descriptions of the low-energy physics of the X-cube model. A key aspect of our constructions is the use of discontinuous fields in the continuum field theory. Spacetime is continuous, but the fields are not., Comment: 46 pages. v3: minor changes

In many gauge theories, the existence of particles in every representation of the gauge group (also known as completeness of the spectrum) is equivalent to the absence of one-form global symmetries. However, this relation does not hold, for example, in the gauge theory of non-abelian finite groups. We refine this statement by considering topological operators that are not necessarily associated with any global symmetry. For discrete gauge theory in three spacetime dimensions, we show that completeness of the spectrum is equivalent to the absence of certain Gukov-Witten topological operators. We further extend our analysis to four and higher spacetime dimensions. Since topological operators are natural generalizations of global symmetries, we discuss evidence for their absence in a consistent theory of quantum gravity., Comment: 33 pages, 10 figures, v2: matches publication version

We study the supersymmetric ground states of the Kronecker model of quiver quantum mechanics. This is the simplest quiver with two gauge groups and bifundamental matter fields, and appears universally in four-dimensional N=2 systems. The ground state degeneracy may be written as a multi-dimensional contour integral, and the enumeration of poles can be simply phrased as counting bipartite trees. We solve this combinatorics problem, thereby obtaining exact formulas for the degeneracies of an infinite class of models. We also develop an algorithm to compute the angular momentum of the ground states, and present explicit expressions for the refined indices of theories where one rank is small., 50 pages, 20 figures, + appendices. v2 typos corrected, color issues in figures fixed

The dislocation slip behaviors in GaN bulk crystal are investigated by nanoindentation, the dislocation distribution patterns formed around an impress are observed by cathodoluminescence (CL) and cross-sectional transmission electron microscope (TEM). Dislocation loops, vacancy luminescence, and cross-slips show hexagonal symmetry around the 〈11-20〉 and 〈1-100〉 direction on c-plane. It is found that the slip planes of dislocation in GaN crystal are dominated in {0001} basal plane and {10-11} pyramid plane. According to the dislocation intersection theory, we come up with the dislocation formation process and the related mechanisms are discussed.

We reformulate known exotic theories (including theories of fractons) on a Euclidean spacetime lattice. We write them using the Villain approach and then we modify them to a convenient range of parameters. The new lattice models are closer to the continuum limit than the original lattice versions. In particular, they exhibit many of the recently found properties of the continuum theories including emergent global symmetries and surprising dualities. Also, these new models provide a clear and rigorous formulation to the continuum models and their singularities. In appendices, we use this approach to review well-studied lattice models and their continuum limits. These include the XY-model, the $\mathbb{Z}_N$ clock-model, and various gauge theories in diverse dimensions. This presentation clarifies the relation between the condensed-matter and the high-energy views of these systems. It emphasizes the role of symmetries associated with the topology of field space, duality, and various anomalies., 66 pages, 1 figure

We study two-dimensional (4, 4) superconformal field theories of central charge c = 6, corresponding to nonlinear sigma models on K3 surfaces, using the superconformal bootstrap. This is made possible through a surprising relation between the BPS N $$ \mathcal{N} $$ = 4 superconformal blocks with c = 6 and bosonic Virasoro conformal blocks with c = 28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum in the K3 CFT are obtained as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A 1 N $$ \mathcal{N} $$ = 4 cigar CFT. We also derive an analytic upper bound on the first nonzero eigenvalue of the scalar Laplacian on K3 in the large volume regime, that depends on the K3 moduli data. As two byproducts, we find an exact equivalence between a class of BPS N $$ \mathcal{N} $$ = 2 superconformal blocks and Virasoro conformal blocks in two dimensions, and an upper bound on the four-point functions of operators of sufficiently low scaling dimension in three and four dimensional CFTs.

We explore the large spin spectrum in two-dimensional conformal field theories with a finite twist gap, using the modular bootstrap in the lightcone limit. By recursively solving the modular crossing equations associated to different $PSL(2,\mathbb{Z})$ elements, we identify the universal contribution to the density of large spin states from the vacuum in the dual channel. Our result takes the form of a sum over $PSL(2,\mathbb{Z})$ elements, whose leading term generalizes the usual Cardy formula to a wider regime. Rather curiously, the contribution to the density of states from the vacuum becomes negative in a specific limit, which can be canceled by that from a non-vacuum Virasoro primary whose twist is no bigger than $c-1\over16$. This suggests a new upper bound of $c-1\over 16$ on the twist gap in any $c>1$ compact, unitary conformal field theory with a vacuum, which would in particular imply that pure AdS$_3$ gravity does not exist. We confirm this negative density of states in the pure gravity partition function by Maloney, Witten, and Keller. We generalize our discussion to theories with $\mathcal{N}=(1,1)$ supersymmetry, and find similar results., 31 pages, v2: added supersymmetric generalization

In this paper, HPM is used as the source of interference to affect the working state of an integrated circuit. The effect of the injected power and the orientation of the studied integrated circuit (FPGA) is investigated. In the experiment, it is found that the induced voltage of the I/O pin can reach 70.3 V under the electromagnetic field high to 1257.44 V/m. In spite of this, the working state of the FPGA remained normal.

The existence of higher-spin quantum conserved currents in two dimensions guarantees quantum integrability. We revisit the question of whether classically-conserved local higher-spin currents in two-dimensional sigma models survive quantization. We define an integrability index $\mathcal{I}(J)$ for each spin $J$, with the property that $\mathcal{I}(J)$ is a lower bound on the number of quantum conserved currents of spin $J$. In particular, a positive value for the index establishes the existence of quantum conserved currents. For a general coset model, with or without extra discrete symmetries, we derive an explicit formula for a generating function that encodes the indices for all spins. We apply our techniques to the $\mathbb{CP}^{N-1}$ model, the $O(N)$ model, and the flag sigma model $\frac{U(N)}{U(1)^{N}}$. For the $O(N)$ model, we establish the existence of a spin-6 quantum conserved current, in addition to the well-known spin-4 current. The indices for the $\mathbb{CP}^{N-1}$ model for $N>2$ are all non-positive, consistent with the fact that these models are not integrable. The indices for the flag sigma model $\frac{U(N)}{U(1)^{N}}$ for $N>2$ are all negative. Thus, it is unlikely that the flag sigma models are integrable., 24 pages, 2 tables

We study the implications of 't Hooft anomaly (i.e. obstruction to gauging) on conformal field theory, focusing on the case when the global symmetry is $\mathbb{Z_2}$. Using the modular bootstrap, universal bounds on (1+1)-dimensional bosonic conformal field theories with an internal $\mathbb{Z_2}$ global symmetry are derived. The bootstrap bounds depend dramatically on the 't Hooft anomaly. In particular, there is a universal upper bound on the lightest $\mathbb{Z_2}$ odd operator if the symmetry is anomalous, but there is no bound if the symmetry is non-anomalous. In the non-anomalous case, we find that the lightest $\mathbb{Z_2}$ odd state and the defect ground state cannot both be arbitrarily heavy. We also consider theories with a $U(1)$ global symmetry, and comment that there is no bound on the lightest $U(1)$ charged operator if the symmetry is non-anomalous., 49+16 pages, 19 figures, 1 table; v2: minor clarifications; v3: typos fixed

We investigate the non-BPS realm of 3d ${\cal N} = 4$ superconformal field theory by uniting the non-perturbative methods of the conformal bootstrap and supersymmetric localization, and utilizing special features of 3d ${\cal N} = 4$ theories such as mirror symmetry and a protected sector described by topological quantum mechanics (TQM). Supersymmetric localization allows for the exact determination of the conformal and flavor central charges, and the latter can be fed into the mini-bootstrap of the TQM to solve for a subset of the OPE data. We examine the implications of the $\mathbb{Z}_2$ mirror action for the SCFT single- and mixed-branch crossing equations for the moment map operators, and apply numerical bootstrap to obtain universal constraints on OPE data for given flavor symmetry groups. A key ingredient in applying the bootstrap analysis is the determination of the mixed-branch superconformal blocks. Among other results, we show that the simplest known self-mirror theory with $SU(2) \times SU(2)$ flavor symmetry saturates our bootstrap bounds, which allows us to extract the non-BPS data and examine the self-mirror $\mathbb{Z}_2$ symmetry thereof., Comment: 50+27 pages, 6 figures, 7 tables. v2: typos corrected, references added. v3: a brief summary added, minor notations changed, SciPost published version

We study light-ray operators constructed from the energy-momentum tensor in $d$-dimensional Lorentzian conformal field theory. These include in particular the average null energy operator. The commutators of parallel light-ray operators on a codimension one light-sheet form an infinite-dimensional algebra. We determine this light-ray algebra and find that the $d$-dimensional (generalized) BMS algebra, including both the supertranslation and the superrotation, is a subalgebra. We verify this algebra in correlation functions of free scalar field theory. We also determine the infinite-dimensional algebra of light-ray operators built from non-abelian spin-one conserved currents., 25 pages

It has long been clear that the conformal bootstrap is associated with a rich geometry. In this paper we undertake a systematic exploration of this geometric structure as an object of study in its own right. We study conformal blocks for the minimal SL(2,R) symmetry present in conformal field theories in all dimensions. Unitarity demands that the Taylor coefficients of the four-point function lie inside a polytope U determined by the operator spectrum, while crossing demands they lie on a plane X. The conformal bootstrap is then geometrically interpreted as demanding a non-empty intersection of U and X. We find that the conformal blocks enjoy a surprising positive determinant property. This implies that U is an example of a famous polytope -- the cyclic polytope. The face structure of cyclic polytopes is completely understood. This lets us fully characterize the intersection U and X by a simple combinatorial rule, leading to a number of new exact statements about the spectrum and four-point function in any conformal field theory., 49 pages, 22 figures v2. Plot of Delta1 Delta2 corrected, references and more detailed discussion on projection of polytopes added

We show that the fermionization of the Monster CFT with respect to $\mathbb{Z}_{2A}$ is the tensor product of a free fermion and the Baby Monster CFT. The chiral fermion parity of the free fermion implies that the Monster CFT is self-dual under the $\mathbb{Z}_{2A}$ orbifold, i.e. it enjoys the Kramers-Wannier duality. The Kramers-Wannier duality defect extends the Monster group to a larger category of topological defect lines that contains an Ising subcategory. We introduce the defect McKay-Thompson series defined as the Monster partition function twisted by the duality defect, and find that the coefficients can be decomposed into the dimensions of the (projective) irreducible representations of the Baby Monster group. We further prove that the defect McKay-Thompson series is invariant under the genus-zero congruence subgroup $16D^0$ of $PSL(2,\mathbb{Z})$., 26+9 pages, 7 figure, 4 tables

Centrifugal pouring is often used in investment casting of large thin-wall Ti castings to promote filling. Shrinkage defects often appear in a Ti casting produced by centrifugal casting. Numerical simulation indicate that shrinkage is caused by these reasons: improper pouring system and thin-wall structure limited feeding of liquid metal from pouring system, and centrifugal force enlarged the shrinkage defects by strengthen feeding of liquid within the casting. Thus centrifugal casting is replaced by gravity casting and a new pouring system is adopted. Obvious shrinkage defects disappear in the new casting process.

This work investigated the energy absorption behavior of expansion circular tubes. This kind of energy absorption device dissipates the impact of kinetic energy through plastic deformation and friction. A finite element model (FEM) was established with reference to the size of the coupler, which was used for connecting two vehicles. A special case was designed to validate the accuracy of the FEM. Furthermore, a theoretical prediction model that took into consideration the additional shear deformation and expansion ratio enlargement was compared with the steady compressional force of the experiment and numerical simulation. The theoretical prediction was accurate. Based on this valid FEM, a series of parameter studies was developed. Specifically, a list of conical mandrels with different angles from 5° to 40° was established, and the coefficient of friction varied from 0 to 0.3. Both had great influence on energy absorption. The relationship between the expansion angle and steady compressional force is nonlinear, while the friction coefficient and steady compressional force are linear. With friction, the inflection point of force curve existed between 10° and 20°.

We study up to 8-derivative terms in the Coulomb branch effective action of (1, 1) little string theory, by collecting results of 4-gluon scattering amplitudes from both perturbative 6D super-Yang-Mills theory up to 4-loop order, and tree-level double scaled little string theory (DSLST). In previous work we have matched the 6-derivative term from the 6D gauge theory to DSLST, indicating that this term is protected on the entire Coulomb branch. The 8-derivative term, on the other hand, is unprotected. In this paper we compute the 8-derivative term by interpolating from the two limits, near the origin and near the infinity on the Coulomb branch, numerically from SU(k) SYM and DSLST respectively, for k = 2, 3, 4, 5. We discuss the implication of this result on the UV completion of 6D SYM as well as the strong coupling completion of DSLST. We also comment on analogous interpolating functions in the Coulomb phase of circle-compactified (2, 0) little string theory., United States. Department of Energy (Contract Number DE-SC00012567), National Science Foundation (U.S.) (Award PHY-0847457), Harvard University (Fundamental Laws Initiative Fund)

We study supervertices in six dimensional (2, 0) supergravity theories, and derive supersymmetry non-renormalization conditions on the 4- and 6-derivative four-point couplings of tensor multiplets. As an application, we obtain exact non-perturbative results of such effective couplings in type IIB string theory compactified on K3 surface, extending previous work on type II/heterotic duality. The weak coupling limit thereof, in particular, gives certain integrated four-point functions of half-BPS operators in the nonlinear sigma model on K3 surface, that depend nontrivially on the moduli, and capture worldsheet instanton contributions., United States. Department of Energy (Contract Number DE-SC00012567)

We study (1+1)-dimensional non-linear sigma models whose target space is the flag manifold $U(N)\over U(N_1)\times U(N_2)\cdots U(N_m)$, with a specific focus on the special case $U(N)/U(1)^{N}$. These generalize the well-known $\mathbb{CP}^{N-1}$ model. The general flag model exhibits several new elements that are not present in the special case of the $\mathbb{CP}^{N-1}$ model. It depends on more parameters, its global symmetry can be larger, and its 't Hooft anomalies can be more subtle. Our discussion based on symmetry and anomaly suggests that for certain choices of the integers $N_I$ and for specific values of the parameters the model is gapless in the IR and is described by an $SU(N)_1$ WZW model. Some of the techniques we present can also be applied to other cases., Comment: 59 pages, 3 figures, 1 table, typos fixed, references added

Motivated by M-theory compactification on elliptic Calabi-Yau threefolds, we present a correspondence between networks of small resolutions for singular elliptic fibrations and Coulomb branches of five-dimensional N=1 gauge theories. While resolutions correspond to subchambers of the Coulomb branch, partial resolutions correspond to higher codimension loci at which the Coulomb branch intersects the Coulomb-Higgs branches. Flops between different resolutions are identified with reflections on the Coulomb branch. Physics aside, this correspondence provides an interesting link between elliptic fibrations and representation theory., 55 pages, 18 figures, section added

Recently, spin-one wavefunctions in four dimensions that are conformal primaries of the Lorentz group SL(2,C) were constructed. We compute low-point, tree-level gluon scattering amplitudes in the space of these conformal primary wavefunctions. The answers have the same conformal covariance as correlators of spin-one primaries in a 2d CFT. The BCFW recursion relation between three- and four-point gluon amplitudes is recast into this conformal basis., 27 pages

We investigate superconformal surface defects in four-dimensional N=2 superconformal theories. Each such defect gives rise to a module of the associated chiral algebra and the surface defect Schur index is the character of this module. Various natural chiral algebra operations such as Drinfeld-Sokolov reduction and spectral flow can be interpreted as constructions involving four-dimensional surface defects. We compute the index of these defects in the free hypermultiplet theory and Argyres-Douglas theories, using both infrared techniques involving BPS states, as well as renormalization group flows onto Higgs branches. In each case we find perfect agreement with the predicted characters., 52 pages, 1 table

We find a simple relation between two-dimensional BPS N=2 superconformal blocks and bosonic Virasoro conformal blocks, which allows us to analyze the crossing equations for BPS 4-point functions in unitary (2,2) superconformal theories numerically with semidefinite programming. We constrain gaps in the non-BPS spectrum through the operator product expansion of BPS operators, in ways that depend on the moduli of exactly marginal deformations through chiral ring coefficients. In some cases, our bounds on the spectral gaps are observed to be saturated by free theories, by N=2 Liouville theory, and by certain Landau-Ginzburg models., Comment: 56 pages, 14 figures

We conjecture a formula for the Schur index of four-dimensional $\mathcal{N}=2$ theories coupled to $(2,2)$ surface defects in terms of the $2d$-$4d$ BPS spectrum in the Coulomb phase of the theory. The key ingredient in our conjecture is a refined $2d$-$4d$ wall-crossing invariant, which we also formulate. Our result intertwines recent conjectures expressing the four-dimensional Schur index in terms of infrared BPS particles, with the Cecotti-Vafa formula for limits of the elliptic genus in terms of two-dimensional BPS solitons. We extend our discussion to framed $2d$-$4d$ BPS states, and use this to demonstrate a general relationship between surface defect indices and line defect indices. We illustrate our results in the example of $SU(2)$ super Yang-Mills coupled to the $\mathbb{CP}^1$ sigma model defect., 50 pages, 1 figure

We study solutions of the Klein-Gordon, Maxwell, and linearized Einstein equations in $\mathbb{R}^{1,d+1}$ that transform as $d$-dimensional conformal primaries under the Lorentz group $SO(1,d+1)$. Such solutions, called conformal primary wavefunctions, are labeled by a conformal dimension $\Delta$ and a point in $\mathbb{R}^d$, rather than an on-shell $(d+2)$-dimensional momentum. We show that the continuum of scalar conformal primary wavefunctions on the principal continuous series $\Delta\in \frac d2+ i\mathbb{R}$ of $SO(1,d+1)$ spans a complete set of normalizable solutions to the wave equation. In the massless case, with or without spin, the transition from momentum space to conformal primary wavefunctions is implemented by a Mellin transform. As a consequence of this construction, scattering amplitudes in this basis transform covariantly under $SO(1,d+1)$ as $d$-dimensional conformal correlators., Comment: 37 pages, 4 tables

We study general properties of the conformal basis, the space of wavefunctions in $(d+2)$-dimensional Minkowski space that are primaries of the Lorentz group $SO(1,d+1)$. Scattering amplitudes written in this basis have the same symmetry as $d$-dimensional conformal correlators. We translate the optical theorem, which is a direct consequence of unitarity, into the conformal basis. In the particular case of a tree-level exchange diagram, the optical theorem takes the form of a conformal block decomposition on the principal continuous series, with OPE coefficients being the three-point coupling written in the same basis. We further discuss the relation between the massless conformal basis and the bulk point singularity in AdS/CFT. Some three- and four-point amplitudes in (2+1) dimensions are explicitly computed in this basis to demonstrate these results., Comment: 31 pages, 3 figures

The four-dimensional (4D) Lorentz group $SL(2,\mathbb{C})$ acts as the two-dimensional (2D) global conformal group on the celestial sphere at infinity where asymptotic 4D scattering states are specified. Consequent similarities of 4D flat space amplitudes and 2D correlators on the conformal sphere are obscured by the fact that the former are usually expressed in terms of asymptotic wavefunctions which transform simply under spacetime translations rather than the Lorentz $SL(2,\mathbb{C})$. In this paper we construct on-shell massive scalar wavefunctions in 4D Minkowski space that transform as $SL(2,\mathbb{C})$ conformal primaries. Scattering amplitudes of these wavefunctions are $SL(2,\mathbb{C})$ covariant by construction. For certain mass relations, we show explicitly that their three-point amplitude reduces to the known unique form of a 2D CFT primary three-point function and compute the coefficient. The computation proceeds naturally via Witten-like diagrams on a hyperbolic slicing of Minkowski space and has a holographic flavor., Comment: 13 pages

An algorithm of uncertain reasoning which more than one result of a new object can be obtained according to the known knowledge is an important part of an expert system. A new object is an especial decision rule which has only a predecessor. In order to resolve the problem that the differences of attributes’ importance in the new object are not considered in traditional methods of uncertain reasoning, a new uncertain reasoning algorithm based on the rules set which is obtained on the basis of the rough set theory is proposed. In the algorithm, both subjective factors and objective factors in the process of reasoning are considered, and the proportion of subjective factors to objective factors can be controlled by users. So the algorithm is better than the tradition method in flexibility and practicability.

OBJECTIVE To determine magnetic resonance imaging (MRI) characteristics of abdominal tuberculous lymphadenopathy. DESIGN Twenty-six consecutive patients (20 men, 6 women; mean age 38 ± 14 years) with documented tuberculosis (TB) in the abdominal lymph nodes were recruited and retrospectively analysed for contour, size, enhancement patterns, signal intensity and anatomic distribution of enlarged lymph nodes, as well as extra-nodal lesions. RESULTS The main anatomic distribution of lymph node involvement included the lesser omentum (80.8%, 21/26), anterior pararenal space (96.2%, 25/26), mesentery (34.6%, 9/26) and the upper para-aortic region (73.1%, 19/26), and, exceptionally, the lower para-aortic region (19.2%, 5/26). Contrast-enhanced T1-weighted images demonstrated predominantly peripheral enhancement in 24 cases (92.3%, 24/26), most of which (80.8%, 21/26) had enlarged lymph nodes with conglomerated multilocular appearance. In 24 peripheral enhancement cases, the contrast-to-noise ratio values were significantly higher for the marginal zones of the enlarged lymph nodes compared to the central zones in each contrast phase (all P < 0.05); the difference in signal-to-noise ratio between the central and marginal zones was found at the portal venous phase (P = 0.04). CONCLUSION The particular anatomic distribution and peripheral enhancement patterns of contrast-enhanced MRI with quantitative analysis might be useful in the diagnosis of abdominal tuberculous lymphadenopathy.

Despite many experimental and clinical studies conducted on distraction osteogenesis (DO) in the past decade, changes in the surrounding tissues that occur after the procedure remains poorly understood. To study the biochemical changes of recovery in nerve tissues upon DO-induced nerve injury, we prepared a rabbit model of tibia lengthening to observe the expression pattern of nerve growth factor (NGF) and low-affinity NGF receptor (p75NGFR) in the distracted tibial nerve. The distracted tibial nerve was harvested at various time points during the consolidation period of new bone formation and immunohistochemical staining was performed to detect the expression of NGF and p75NGFR. The expression levels of NGF and p75NGFR were found to be different at various times after DO. The changes in expression of these two cellular factors show similar tendencies with significantly elevated expression in Schwann cells at 7 and 14 days after distraction, but low or undetectable levels of expression at 0, 28, and 56 days. These results suggest that NGF and p75NGFR may play important roles in the adaptive process of the distracted nerve. NGF and p75NGFR are autocrine growth factors present in the distracted nerve during the early consolidation period. NGF interacts with p75NGFR to promote damage repair and reconstruction of nerves. Together, this study furthers the understanding of the relative mechanisms of nerve repair, as well as provides a further basis for the clinical application of neurotrophins.

To investigate the imaging manifestations of 16-slice enhanced CT of parotid adenolymphoma in the parotid gland and the corresponding pathology,in order to improve the understanding of the CT imaging manifestations of parotid adenolymphoma in the parotid gland.The enhanced CT characteristics of 34 cases of parotid adenolymphoma in the parotid gland confirmed by histological pathology were retrospectively analyzed.There were totally 86 lesions in 34 cases, of which 12 cases with lesions in bilateral sides and 22 cases with lesions in unilateral side. Sixty-six lesions located behind and below the superficial lobe of the parotid gland. The lesions showed moderate to obvious enhancement at arterial phase, and the cystic region within the lesions showed no enhancement.The relatively specific enhanced MSCT manifestations of parotid adenolymphoma in parotid gland include lesions located behind and below the superficial lobe of parotid gland unilaterally or bilaterally, sometimes exhibited as multiple masses, with clear edge, obvious enhancement and cystic degeneration inside.

We derive a localization formula for the refined index of gauged quantum mechanics with four supercharges. Our answer takes the form of a residue integral on the complexified Cartan subalgebra of the gauge group. The formula captures the dependence of the index on Fayet-Iliopoulos parameters and the presence of a generic superpotential. The residue formula provides an efficient method for computing cohomology of quiver moduli spaces. Our result has broad applications to the counting of BPS states in four-dimensional N=2 systems. In that context, the wall-crossing phenomenon appears as discontinuities in the value of the residue integral as the integration contour is varied. We present several examples illustrating the various aspects of the index formula., Comment: 30 pages, 12 figures, v2 references added, minor clarifications, and changes to sign conventions for FI parameters

We conjecture a precise relationship between the Schur limit of the superconformal index of four-dimensional $\mathcal{N}=2$ field theories, which counts local operators, and the spectrum of BPS particles on the Coulomb branch. We verify this conjecture for the special case of free field theories, $\mathcal{N}=2$ QED, and $SU(2)$ gauge theory coupled to fundamental matter. Assuming the validity of our proposal, we compute the Schur index of all Argyres-Douglas theories. Our answers match expectations from the connection of Schur operators with two-dimensional chiral algebras. Based on our results we propose that the chiral algebra of the generalized Argyres-Douglas theory $(A_{k-1},A_{N-1})$ with $k$ and $N$ coprime, is the vacuum sector of the $(k,k+N)$ $W_{k}$ minimal model, and that the Schur index is the associated vacuum character., Comment: 46 pages, 12 figures. v2: revisions to section 1, references added

This study aimed to investigate energy dissipation in train collisions. A 1/8 scaled train model, about one-dimensional in longitudinal direction, was used to carry out a scaled train collision test. Corresponding multibody dynamic simulations were conducted using traditional and improved method model (IMM) in ADAMS. In IMM, the connection between two adjacent cars was expressed by a nonlinear spring and energy absorbing structures were equivalently represented by separate forces, instead of one force. IMM was able to simulate the motion of each car and displayed the deformation of structures at both ends of the cars. IMM showed larger deformations and energy absorption of structures in moving cars than those in stationary cars. Moreover, the asymmetry in deformation proportion in main energy absorbing structures decreased with increasing collision speed. The asymmetry decreased from 11.69% to 3.60% when the collision speed increased from 10 km/h to 36 km/h.

OBJECTIVE: To determine the features that differentiate earthquake-related crush extremity fractures from non-earthquake-related extremity fractures by using digital radiography (DR) and multidetector row computed tomography (MDCT). METHODS: Six hundred and twenty-three consecutive victims with crush extremity fractures arising from the 2008 Sichuan earthquake, including 611 undergoing DR and 12 undergoing MDCT, entered the test group, and 316 consecutive victims with non-earthquake-related extremity fractures, including 301 undergoing DR and 15 undergoing MDCT, were enrolled in the control group. Image data were reviewed retrospectively and statistically between groups focusing on the anatomic distributions, numbers and types of extremity fractures. RESULTS: Fractures involving multiple extremities were more likely in the test group than the control group (88/623 vs 27/316 victims, P Language: en

Poster: "RANZCR-AOCR 2012 / R-0150 / Dynamic Assessment of Aortic Annulus in Patients with Aortic Stenosis throughout Cardiac Cycle with Dual-source Computed Tomography" by: "Z. G. Yang, L.-Q. Peng, H. Shao, J.-Q. Yu"

Background— The anatomic features of left atrial diverticula (LAD) are still unclear in patients with atrial fibrillation (AF). The purpose of this study was to evaluate the prevalence and morphological characteristics of LAD in patients referred for radiofrequency transcatheter ablation of AF with dual-source computed tomography. Methods and Results— Dual-source computed tomography images were obtained in 214 patients referred for AF catheter ablation and 214 sex- and age-matched control subjects. Images were analyzed to determine the prevalence and morphological characteristics of LAD and their relationship with adjacent pulmonary veins and left atrial appendage. In AF patients 77 (36.0%) (95% confidence interval, 29.6–42.4%) had 90 LAD, whereas in control subjects 70 (32.7%) (95% confidence interval, 26.4–39.0%) had 81 LAD ( P =0.551). In patients with AF, LAD locations were right anterosuperior (47.8%), left anterosuperior (8.9%), left lateral (32.2%), interatrial septum (4.4%), right inferior (5.6%), and posterosuperior (1.1%) walls, respectively. The mean size of LAD was 5.3±2.9×5.6±3.3 mm. The wall of the LAD was much thinner than that of adjacent left atrium (0.89±0.46 versus 2.39±0.83 mm). Most LAD were located close to a pulmonary vein or atrial appendage ostium, with a mean distance of 8.7–13.1 mm. Conclusions— LAD are common, with a prevalence of 36.0% in patients with AF, which is not statistically greater than that in patients without AF. Thin-walled LAD are more commonly located on the superior anterior wall of left atrium and close to common ablation sites.

Emergency resources supply includes emergency resources reserves and emergency resources mobilization. This study utilizes system dynamics to model emergency resources supply and simulate to give engineering presentation. Simulation results show that emergency resources supply is decided by the need, the aim of employing quantity and mobilizing quantity is to bridge employing error and mobilizing error. The results also show oversupply of emergency resources, namely excessive employing and excessive mobilization, is decided by transportation and demand error which is caused by arrival supply quantity.

OBJECTIVE: To investigate the correlation between enhanced computed tomography (CT) findings and pathological results of rare parotid gland tumors, and improve diagnosis accuracy. METHODS: The enhanced CT manifestations of 22 cases with pathologically documented rare parotid gland tumors, which included 6 cases of basal cell tumor, 5 cases of myoepithelioma, 4 cases of vascular invasion, 3 cases of lymphatic cyst, 3 cases of lipoma, and 1 case of chondrosarcoma, were retrospectively analyzed. The location, size, shape, density, and relationship with surrounding structure were evaluated on CT images. RESULTS: The enhanced CT showed that basal cell tumors occurred in the superficial lobe of the parotid gland, with clear boundary, within the cystic lesion. The lesions were moderate to obviously enhanced, which may be accompanied by enlarged lymph nodes. Myoepithelial tumors were located in the superficial lobe of the parotid gland, with a small cystic prone and microcalcification within a few cases. The lesions were moderate to obviously enhanced. Hemangiomas of soft tissue mass prominent in the parotid gland surface were mild to significantly enhanced. Larger lesions may occupy the entire parotid gland, with uneven density and visible vein stone. The CT density values of ​the ​lymphatic cyst were usually higher. Chondrosarcoma mainly manifested cystic mass at the calcification edge. Lipoma with fat density mass exhibited clear boundary without enhancement. Fiber separation could be observed in the lesion. CONCLUSION: CT can reflect the pathological features of rare parotid gland tumors by demonstrating their corresponding imaging features. Enhanced CT is the most effective means of imaging to identify the nature of rare tumor of the parotid gland lesions.

To evaluate the operative method and clinical outcome for the treatment of posttraumatic equinus deformity and concomitant soft tissue defect of the heel.Between June 2006 and May 2010, seven cases of posttraumatic equinus deformity and concomitant unstable scar or ulcer of the heels were treated by using a hinged Ilizarov apparatus and reversed sural fasciocutaneous island flap transfer. Achilles tendon lengthening was also done in all patients. The average duration of follow-up was 21 months. The sizes of sural flaps were from 7 cm × 6 cm to 10 cm × 9 cm. Two weeks after the flap transfer, distraction of the Ilizarov fixator was initiated to gradually correct the equinus position of the foot.Results were evaluated by using the following criteria: (1) the degree of active dorsiflexion of the ankle, (2) the total active range of motion of the ankle, and (3) walking ability and flap durability. For active dorsiflexion of the ankle, the results were good in three patients and fair in four patients. For range of active motion of the ankle, the results were good in five patients and fair in two patients. For walking ability and flap durability, the results were good in six patients and fair in one patient.This study showed that posttraumatic equinus deformity accompanied by soft tissue defect of the heel can be treated effectively with Achilles tendon lengthening, reversed sural fasciocutaneous island flap transfer, and a hinged Ilizarov technique.

It is widely acknowledged that image thinking is significant in medical education. The colorful pictures and animations need to be presented for the users (observers) to make the content easier to be understood. By the appropriate matching of pictures and text, readers are able to associate the text with the image on the screen to reach better understanding. In this case, 3d and dynamic images will take the place of the plane and static ones. The study software applied the image processing software and animation software, such as Photoshop, Flash software. 3d max software is used for processing and preparation the simulation stereo skeleton. the Java language of Cult 3D models help give the characteristics of model rotating and zooming in and out; Using multimedia interactive software, Neobook, makes sure interactive amity of interface and establishes a good interactive operating environment between the users and 3d models. For the basic medical education which has higher visual thinking demand, multimedia education has already be widespreaded and used. This software has interactive function and three-dimensional content, 3d instead of static, dynamic replace static state. It is not only keeping the traditional advantage (such as the logical arrangement of content, strictly text description, etc.), but also providing the learning reference material to the users which has intuitive visual experience, independently and freely self-selection, flexible processing. It is beneficial to understand and learn related contents. This study software shows rich and colorful pictures, 3d dynamic display contents, animation process of image to the users, so as to increase understanding and grasping the contents on human spine. It has multiple functions such as help studying and teaching.

INTRODUCTION The aim of this preliminary study was to evaluate the effect of long-term progesterone (P4) treatment on structural and functional deficits associated with the hippocampus. MATERIAL AND METHODS Mice served as sham controls or were bilaterally ovariectomized (Ovx), and a 90-day regimen of placebo or P4 was applied to the animal. After the administration, the acquisition and retrieval of mice in contextual fear conditioning (CFC) and a water maze were examined. Hippocampal tissues from some mice in each group were stained with cresyl violet, and the remainder were taken for determining the antioxidant power. RESULTS Compared with placebo controls, the time spent on freezing was higher and the latencies were longer for mice given high-dose P4 (HP) (p < 0.05) in CFC, and the HP group also had longer searching time spent in the target quadrant (p < 0.05) in the water maze. Compared with placebo controls, the cell number of hippocampus CA1, CA3 and DG was significantly higher in the HP group (p < 0.05), and the thickness of the cell layer in CA1 and DG was also higher in the HP group (p < 0.05). All the oxidative stress biomarkers show that the antioxidative activity in hippocampus tissue from the HP and LP groups is higher than that in placebo controls (p < 0.05). CONCLUSIONS Ovx impairs learning and memory of mice, which can be rescued by a long-term regimen of HP via its antioxidant effects.

We analyze solutions to loop-truncated Schwinger-Dyson equations in massless N = 2 and N = 4 Wess-Zumino matrix quantum mechanics at finite temperature, where conventional perturbation theory breaks down due to IR divergences. We find a rather intricate low temperature expansion that involves fractional power scaling in the temperature, based on a consistent “soft collinear” approximation. We conjecture that at least in the N = 4 matrix quantum mechanics, such scaling behavior holds to all perturbative orders in the 1/N expansion. We discuss some preliminary results in analyzing the gauged supersymmetric quantum mechanics using Schwinger-Dyson equations, and comment on the connection to metastable microstates of black holes in the holographic dual of BFSS matrix quantum mechanics., Harvard University (Fundamental Laws Initiative Fund), National Science Foundation (U.S.) (Award PHY-0847457)