1,422 research outputs found
Euclidean 4d exact solitons in a Skyrme type model
We introduce a Skyrme type, four dimensional Euclidean field theory made of a
triplet of scalar fields n, taking values on the sphere S^2, and an additional
real scalar field phi, which is dynamical only on a three dimensional surface
embedded in R^4. Using a special ansatz we reduce the 4d non-linear equations
of motion into linear ordinary differential equations, which lead to the
construction of an infinite number of exact soliton solutions with vanishing
Euclidean action. The theory possesses a mass scale which fixes the size of the
solitons in way which differs from Derrick's scaling arguments. The model may
be relevant to the study of the low energy limit of pure SU(2) Yang-Mills
theory.Comment: 8 pages, 1 eps figure, plain latex, Comments on a possible connection
with the low energy limit of pure SU(2) Yang-Mills theory are added. One
reference added. Version accepted in Physics Letters
Scanning from heating: 3D shape estimation of transparent objects from local surface heating
Today, with quality becoming increasingly important, each product requires three-dimensional in-line quality control. On the other hand, the 3D reconstruction of transparent objects is a very difficult problem in computer vision due to transparency and specularity of the surface. This paper proposes a new method, called Scanning From Heating (SFH), to determine the surface shape of transparent objects using laser surface heating and thermal imaging. Furthermore, the application to transparent glass is discussed and results on different surface shapes are presented
Subnational democratization and the onset of the Mexican drug war
The Mexican drug war escalated dramatically since 2007. However, its origin is in the 1990s turf wars involving the main drug trafficking organisations operating in the country. In this study we seek to examine the main cause of turf wars at the municipal level between 1995-2006. In particular, we highlight the significant role of a large-scale land titling reform (PROCEDE) that secured property rights for the electorate, previously controlled by the state party (PRI) for seven decades. Our results indicate that political change at the municipality level after the rollout of PROCEDE is a significant determinant of organised crime deaths (OCDs). We further provide evidence that the effect is exacerbated when municipal political change is combined with a change at the gubernational level. We also show that increased intercartel violence is inextricably linked to the geographic expansion of cartel operations. Overall, the fall of the PRI at the subnational level after the rollout of PROCEDE - to signify its strong local roots - broke the equilibrium between corrupted local officials and local drug cartels making the latter more vulnerable to expansion operations of rival cartels resulting in more OCDs
Symmetries of generalized soliton models and submodels on target space
Some physically relevant non-linear models with solitons, which have target
space , are known to have submodels with infinitly many conservation laws
defined by the eikonal equation. Here we calculate all the symmetries of these
models and their submodels by the prolongation method. We find that for some
models, like the Baby Skyrme model, the submodels have additional symmetries,
whereas for others, like the Faddeev--Niemi model, they do not.Comment: 18 pages, one Latex fil
ALMA Observations of the Water Fountain Pre-Planetary Nebula IRAS 16342-3814: High-velocity bipolar jets and an Expanding Torus
R. Sahai, W.H.T. Vlemmings, T. Gledhill, C. Sanchez Contreras, E. Lagadec, L-A Nyman, and G. Quintana-Lacaci, ‘ALMA Observations of the Water Fountain Pre-planetary Nebula IRAS 16342-3814: High-velocity Bipolar Jets and an Expanding Torus’, The Astrophysical Journal Letters, Vol 835: L13 (6 pp), published 20 January 2017. The version of record is available online via doi: 10.3847/2041-8213/835/1/L13 © 2017. The American Astronomical Society. All rights reserved.We have mapped 12CO J=3–2 and other molecular lines from the “water fountain” bipolar pre-planetary nebula (PPN) IRAS 16342-3814 with ∼0.35″ resolution using Atacama Large Millimeter/submillimeter Array. We find (i) two very high-speed knotty, jet-like molecular outflows; (ii) a central high-density (>few x106 cm−3), expanding torus of diameter 1300 au; and (iii) the circumstellar envelope of the progenitor AGB, generated by a sudden, very large increase in the mass-loss rate to >3.5 x10-4 Ms yr−1 in the past ∼455 years. Strong continuum emission at 0.89 mm from a central source (690 mJy), if due to thermally emitting dust, implies a substantial mass (0.017 Ms) of very large (∼millimeter-sized) grains. The measured expansion ages of the above structural components imply that the torus (age∼160 years) and the younger high-velocity outflow (age∼110 years) were formed soon after the sharp increase in the AGB mass-loss rate. Assuming a binary model for the jets in IRAS 16342, the high momentum rate for the dominant jet-outflow in IRAS 16342 implies a high minimum accretion rate, ruling out standard Bondi–Hoyle–Lyttleton wind accretion and wind Roche-lobe overflow (RLOF) models with white-dwarf or main-sequence companions. Most likely, enhanced RLOF from the primary or accretion modes operating within common-envelope evolution are needed.Peer reviewedFinal Published versio
Interaction of two modulational instabilities in a semiconductor resonator
The interaction of two neighboring modulational instabilities in a coherently driven semiconductor cavity is investigated. First, an asymptotic reduction of the general equations is performed in the limit of a nearly vertical input-output characteristic. Next, a normal form is derived in the limit where the two instabilities are close to one other. An infinity of branches of periodic solutions are found to emerge from the unstable portion of the homogeneous branch. These branches have a nontrivial envelope in the bifurcation diagram that can either smoothly join the two instability points or form an isolated branch of solutions
Cutaneous Biology: In vivo blockade of pemphigus vulgaris acantholysis by inhibition of intracellular signal transduction cascades
Pemphigus vulgaris (PV) is an autoimmune disease characterized by
mucocutaneous intraepithelial blisters and pathogenic autoantibodies against
desmoglein 3. The mechanism of blister formation in pemphigus has not been
defined; however, in vitro data suggest a role for activation of intracellular
signalling cascades. OBJECTIVES: To investigate the contribution of these
signalling pathways to the mechanism of PV IgG-induced acantholysis in vivo.
METHODS: We used the passive transfer mouse model. Mice were injected with IgG
fractions of sera from a patient with PV, with or without pretreatment with
inhibitors of proteins that mediate intracellular signalling cascades. RESULTS:
Inhibitors of tyrosine kinases, phospholipase C, calmodulin and the
serine/threonine kinase protein kinase C prevented PV IgG-induced acantholysis in
vivo. CONCLUSIONS: These observations strongly support the role of intracellular
signalling cascades in the molecular mechanism of PV IgG-induced acantholysi
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