235 research outputs found
Guided mesh normal filtering
The joint bilateral filter is a variant of the standard bilateral filter, where the range kernel is evaluated using a guidance signal instead of the original signal. It has been successfully applied to various image processing problems, where it provides more flexibility than the standard bilateral filter to achieve high quality results. On the other hand, its success is heavily dependent on the guidance signal, which should ideally provide a robust estimation about the features of the output signal. Such a guidance signal is not always easy to construct. In this paper, we propose a novel mesh normal filtering framework based on the joint bilateral filter, with applications in mesh denoising. Our framework is designed as a two-stage process: first, we apply joint bilateral filtering to the face normals, using a properly constructed normal field as the guidance; afterwards, the vertex positions are updated according to the filtered face normals. We compute the guidance normal on a face using a neighboring patch with the most consistent normal orientations, which provides a reliable estimation of the true normal even with a high-level of noise. The effectiveness of our approach is validated by extensive experimental results
Static/Dynamic Filtering for Mesh Geometry
The joint bilateral filter, which enables feature-preserving signal smoothing
according to the structural information from a guidance, has been applied for
various tasks in geometry processing. Existing methods either rely on a static
guidance that may be inconsistent with the input and lead to unsatisfactory
results, or a dynamic guidance that is automatically updated but sensitive to
noises and outliers. Inspired by recent advances in image filtering, we propose
a new geometry filtering technique called static/dynamic filter, which utilizes
both static and dynamic guidances to achieve state-of-the-art results. The
proposed filter is based on a nonlinear optimization that enforces smoothness
of the signal while preserving variations that correspond to features of
certain scales. We develop an efficient iterative solver for the problem, which
unifies existing filters that are based on static or dynamic guidances. The
filter can be applied to mesh face normals followed by vertex position update,
to achieve scale-aware and feature-preserving filtering of mesh geometry. It
also works well for other types of signals defined on mesh surfaces, such as
texture colors. Extensive experimental results demonstrate the effectiveness of
the proposed filter for various geometry processing applications such as mesh
denoising, geometry feature enhancement, and texture color filtering
Correlated Dynamics of the O(P-3) + CHD3(v=0) Reaction : A Joint Crossed-Beam and Quasiclassical Trajectory Study
Crossed beam experiments and quasiclassical trajectory computations on an ab initio potential energy surface are performed for the O(P-3) + CHD3(v=0) --> OH(V'=0) + CD3(v(2)=0,2) and OD(v'=0,1) + CHD2(v=0) reactions. Both experiment and theory show that the excitation functions display a concave-up behavior and the angular distributions are backward scattered, indicating a direct rebound mechanism and a tight-bend transition state. The reaction produces mainly ground-state products showing the dominance of a vibrationally adiabatic reaction pathway. The Standard histogram binning cannot reproduce the observed vibrational adiabaticity, Whereas Gausgian binning give good agreement with experitnent
CofiFab: Coarse-to-fine fabrication of large 3D objects
This paper presents CofiFab, a coarse-to-fine 3D fabrication solution, which combines 3D printing and 2D laser cutting for cost-effective fabrication of large objects at lower cost and higher speed. Our key approach is to first build coarse internal base structures within the given 3D object using laser-cutting, and then attach thin 3D-printed parts, as an external shell, onto the base to recover the fine surface details. CofiFab achieves this with three novel algorithmic components. First, we formulate an optimization model to compute fabricatable polyhedrons of maximized volume, as the geometry of the internal base. Second, we devise a new interlocking scheme to tightly connect laser-cut parts into a strong internal base, by iteratively building a network of nonorthogonal interlocking joints and locking parts around polyhedral corners. Lastly, we also optimize the partitioning of the external object shell into 3D-printable parts, while saving support material and avoiding overhangs. These components also consider aesthetics, stability and balancing in addition to cost saving. As a result, CofiFab can efficiently produce large objects by assembly. To evaluate its effectiveness, we fabricate objects of varying shapes and sizes, where CofiFab significantly improves compared to previous methods
Supersymmetric Pati-Salam Models from Intersecting D6-branes: A Road to the Standard Model
We provide a systematic construction of three-family N=1 supersymmetric
Pati-Salam models from Type IIA orientifolds on \IT^6/(\IZ_2\times \IZ_2)
with intersecting D6-branes. All the gauge symmetry factors arise from the stacks of D6-branes with U(n) gauge
symmetries, while the ``hidden sector'' is specified by branes,
parallel with the orientifold planes or their images. The
Pati-Salam gauge symmetry can be broken down to the via D6-brane splittings, and
further down to the Standard Model via D- and F-flatness preserving Higgs
mechanism from massless open string states in a N=2 subsector. The models also
possess at least two confining hidden gauge sectors, where gaugino condensation
can in turn trigger supersymmetry breaking and (some) moduli stabilization. The
systematic search yields 11 inequivalent models: 8 models with less than 9
Standard model Higgs doublet-pairs and 1 model with only 2 Standard Model Higgs
doublet-pairs, 2 models possess at the string scale the gauge coupling
unification of and , and all the models possess additional
exotic matters. We also make preliminary comments on phenomenological
implications of these models.Comment: RevTeX4, 48 pages, 18 tables, typos fixed, added comments on
confinement of massless chiral exotics, accepted for publication in Nucl.
Phys.
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Epigenetic Down-Regulation of Sirt 1 via DNA Methylation and Oxidative Stress Signaling Contributes to the Gestational Diabetes Mellitus-Induced Fetal Programming of Heart Ischemia-Sensitive Phenotype in Late Life.
Rationale: The incidence of gestational diabetes mellitus (GDM) is increasing worldwide. However, whether and how GDM exposure induces fetal programming of adult cardiac dysfunctional phenotype, especially the underlying epigenetic molecular mechanisms and theranostics remain unclear. To address this problem, we developed a late GDM rat model. Methods: Pregnant rats were made diabetic on day 12 of gestation by streptozotocin (STZ). Experiments were conducted in 6 weeks old offspring. Results: There were significant increases in ischemia-induced cardiac infarction and gender-dependent left ventricular (LV) dysfunction in male offspring in GDM group as compared to controls. Exposure to GDM enhanced ROS level and caused a global DNA methylation in offspring cardiomyocytes. GDM attenuated cardiac Sirt 1 protein and p-Akt/Akt levels, but enhanced autophagy-related proteins expression (Atg 5 and LC3 II/LC3 I) as compared to controls. Ex-vivo treatment of DNA methylation inhibitor, 5-Aza directly inhibited Dnmt3A and enhanced Sirt 1 protein expression in fetal hearts. Furthermore, treatment with antioxidant, N-acetyl-cysteine (NAC) in offspring reversed GDM-mediated DNA hypermethylation, Sirt1 repression and autophagy-related gene protein overexpression in the hearts, and rescued GDM-induced deterioration in heart ischemic injury and LV dysfunction. Conclusion: Our data indicated that exposure to GDM induced offspring cardiac oxidative stress and DNA hypermethylation, resulting in an epigenetic down-regulation of Sirt1 gene and aberrant development of heart ischemia-sensitive phenotype, which suggests that Sirt 1-mediated signaling is the potential therapeutic target for the heart ischemic disease in offspring
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Inhibition of Autophagy Signaling via 3-methyladenine Rescued Nicotine-Mediated Cardiac Pathological Effects and Heart Dysfunctions.
Rationale: Cigarette smoking is a well-established risk factor for myocardial infarction and sudden cardiac death. The deleterious effects are mainly due to nicotine, but the mechanisms involved and theranostics remain unclear. Thus, we tested the hypothesis that nicotine exposure increases the heart sensitivity to ischemia/reperfusion injury and dysfunction, which can be rescued by autophagy inhibitor. Methods: Nicotine or saline was administered to adult rats via subcutaneous osmotic minipumps in the absence or presence of an autophagy inhibitor, 3-methyladenine (3-MA). After 30 days of nicotine treatment, the rats underwent the cardiac ischemia/reperfusion (I/R) procedure and echocardiography analysis, and the heart tissues were isolated for molecular biological studies. Results: Nicotine exposure increased I/R-induced cardiac injury and cardiac dysfunction as compared to the control. The levels of autophagy-related proteins including LC3 II, P62, Beclin1, and Atg5 were upregulated in the reperfused hearts isolated from nicotine-treated group. In addition, nicotine enhanced cardiac and plasma ROS production, and increased the phosphorylation of GSK3β (ser9) in the left ventricle tissues. Treatment with 3-MA abolished nicotine-mediated increase in the levels of autophagy-related proteins and phosphorylation of GSK3β, but had no effect on ROS production. Of importance, 3-MA ameliorated the augmented I/R-induced cardiac injury and dysfunction in the nicotine-treated group as compared to the control. Conclusion: Our results demonstrate that nicotine exposure enhances autophagy signaling pathway, resulting in development of ischemic-sensitive phenotype of heart. It suggests a potentially novel therapeutic strategy of autophagy inhibition for the treatment of ischemic heart disease
Quasi-Supersymmetric Unification from Intersecting D6-Branes on Type IIA Orientifolds
We construct three quasi-supersymmetric GUT models with symmetry
and gauge coupling unification from intersecting D6-branes on Type IIA
orientifolds. The Standard Model fermions and Higgs doublets can be embedded
into the bifundamental representations in these models, and there is no any
other unnecessary massless representation. Especially in Model I with gauge
group , we just have three-family SM fermions and three pairs of Higgs
particles. The gauge symmetry in these models can be broken down to the
Standard Model gauge symmetry by introducing light open string states. And 1
TeV scale supersymmetry breaking soft masses imply the reasonable intermediate
string scale.Comment: Latex, 14 pages, typos fixed, version to appear in PL
D6-brane Splitting on Type IIA Orientifolds
We study the open-string moduli of supersymmetric D6-branes, addressing both
the string and field theory aspects of D6-brane splitting on Type IIA
orientifolds induced by open-string moduli Higgsing (i.e., their obtaining
VEVs). Specifically, we focus on the Z_2 x Z_2 orientifolds and address the
symmetry breaking pattern for D6-branes parallel with the orientifold 6-planes
as well as those positioned at angles. We demonstrate that the string theory
results, i.e., D6-brane splitting and relocating in internal space, are in one
to one correspondence with the field theory results associated with the
Higgsing of moduli in the antisymmetric representation of Sp(2N) gauge symmetry
(for branes parallel with orientifold planes) or adjoint representation of U(N)
(for branes at general angles). In particular, the moduli Higgsing in the
open-string sector results in the change of the gauge structure of D6-branes
and thus changes the chiral spectrum and family number as well. As a
by-product, we provide the new examples of the supersymmetric Standard-like
models with the electroweak sector arising from Sp(2N)_L x Sp(2N)_R gauge
symmetry; and one four-family example is free of chiral Standard Model exotics.Comment: 44 pages, 7 figures; The anomaly-free models in Subsections 4.2 and
4.3 presented, references added, typos fixe
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