713 research outputs found
Does the Gursey-Tze Solution Represent a Monopole Condensate?
We recast the quaternionic Gursey-Tze solution, which is a fourfold
quasi-periodic self-dual Yang-Mills field with a unit instanton number per
Euclidean spacetime cell, into an ordinary coordinate formulation. After
performing the sum in the Euclidean time direction, we use an observation by
Rossi which suggests the solution represents an arrangement with a BPS monopole
per space lattice cell. This may provide a concrete realization of a monopole
condensate in pure Yang-Mills theory.Comment: 12 pages, Latex
Synthesis of two phloroglucinol derivatives with cinnamyl moieties as inhibitors of the carbonic anhydrase isozymes I and II: an in vitro study
AbstractTwo cinnamyl-substituted phloroglucinols, 4-p-methoxycinnamyl phloroglucinol (9) and 4,6-bis-p-methoxycinnamyl phloroglucinol (10) were synthesized. Two carbonic anhydrases, human carbonic anhydrase I and II (hCA I and II), were purified. Kinetic interactions between these isozymes with 9 and 10 were investigated. These new compounds exhibited inhibitory effects on the hCA I and II enzymes' activity in vitro. The combination of the inhibitory effects of both phloroglucinol and p-coumaric acid groups in a single compound was explored. However, relative to the inhibitory effects of the two groups separately, compounds 9 and 10 demonstrated comparable inhibitory effects. More effective inhibitors of CAs could be created by testing these compounds on other CA isozymes
Kinetic and in silico analysis of thiazolidin-based inhibitors of α-carbonic anhydrase isoenzymes.
Durdagi, Serdar/0000-0002-0426-0905 WOS: 000314531000019 PubMed: 23173744 Carbonic anhydrases (CAs, EC 4.2.1.1) are inhibited by sulfonamides, inorganic anions, phenols, salicylic acid derivatives (acting as drug or prodrugs). A novel class of CA inhibitors (CAIs), interacting with the CA isozymes I and II (cytosolic) in a different manner, is reported here. Kinetic measurements allowed us to identify thiazolidin-based compounds as submicromolar-low micromolar inhibitors of these two CA isozymes. Molecular docking studies of a set of such inhibitors within CA I and II active site allowed us to understand the inhibition mechanism. This new class of inhibitors bind differently compared to other classes of inhibitors known to date: they were found between the phenol-binding site, filling thus the middle of the enzyme cavity
Primary Molar Pulpotomies with Different Hemorrhage Control Agents and Base Materials: A Randomized Clinical Trial
Objective: To evaluate the clinical and radiographical success of primary molar pulpotomies which used 15.5% ferric sulfate (FS) or 1.25% sodium hypochlorite (NaOCl) for hemostasis and zinc oxide-eugenol (ZOE) and calcium hydroxide (CH) pastes as base materials.
Methods: In 29 healthy children, 80 primary molars were randomly allocated to one of the study groups: Group 1: FS-ZOE, Group 2: FS-CH, Group 3: NaOCl-ZOE, and Group 4: NaOCl-CH. After hemostasis with the respective solutions, pulp stumps and floor of the pulp chambers were covered with either ZOE or CH pastes. All teeth were restored with stainless steel crowns. Follow-up examinations were carried out at 1, 3, 6, and 12 months.
Results: One tooth in Group 1 and two teeth in Group 4 were extracted because of pain and periapial pathosis at sixth month. After 12 months, clinical success rates of pulpotomies in Groups 1-4 were 95%, 100%, 100%, and 89.5%, respectively. The differences were not significant (P = 0.548). Radiographic success rates for Groups 1-4 were 80%, 88.9%, 78.9%, and 84.2%, respectively. No statistically significant difference was found (P = 0.968). Pain on percussion was the most observed clinical finding. However, internal root resorption was the most common radiological finding and it was observed significantly more in mandibular primary molars (P \u3c 0.05).
Conclusion: Both ZOE and CH can be preferred as base materials after hemostasis achieved by the use of 15.5% FS or 1.25% NaOCl in primary tooth pulpotomy
Self-Supervised Learning with an Information Maximization Criterion
Self-supervised learning allows AI systems to learn effective representations
from large amounts of data using tasks that do not require costly labeling.
Mode collapse, i.e., the model producing identical representations for all
inputs, is a central problem to many self-supervised learning approaches,
making self-supervised tasks, such as matching distorted variants of the
inputs, ineffective. In this article, we argue that a straightforward
application of information maximization among alternative latent
representations of the same input naturally solves the collapse problem and
achieves competitive empirical results. We propose a self-supervised learning
method, CorInfoMax, that uses a second-order statistics-based mutual
information measure that reflects the level of correlation among its arguments.
Maximizing this correlative information measure between alternative
representations of the same input serves two purposes: (1) it avoids the
collapse problem by generating feature vectors with non-degenerate covariances;
(2) it establishes relevance among alternative representations by increasing
the linear dependence among them. An approximation of the proposed information
maximization objective simplifies to a Euclidean distance-based objective
function regularized by the log-determinant of the feature covariance matrix.
The regularization term acts as a natural barrier against feature space
degeneracy. Consequently, beyond avoiding complete output collapse to a single
point, the proposed approach also prevents dimensional collapse by encouraging
the spread of information across the whole feature space. Numerical experiments
demonstrate that CorInfoMax achieves better or competitive performance results
relative to the state-of-the-art SSL approaches
Tests and applications of self-consistent cranking in the interacting boson model
The self-consistent cranking method is tested by comparing the cranking
calculations in the interacting boson model with the exact results obtained
from the SU(3) and O(6) dynamical symmetries and from numerical
diagonalization. The method is used to study the spin dependence of shape
variables in the and boson models. When realistic sets of parameters
are used, both models lead to similar results: axial shape is retained with
increasing cranking frequency while fluctuations in the shape variable
are slightly reduced.Comment: 9 pages, 3 ps figures, Revte
Ab Initio Structural Energetics of Beta-Si3N4 Surfaces
Motivated by recent electron microscopy studies on the Si3N4/rare-earth oxide
interfaces, the atomic and electronic structures of bare beta-Si3N4 surfaces
are investigated from first principles. The equilibrium shape of a Si3N4
crystal is found to have a hexagonal cross section and a faceted dome-like base
in agreement with experimental observations. The large atomic relaxations on
the prismatic planes are driven by the tendency of Si to saturate its dangling
bonds, which gives rise to resonant-bond configurations or planar sp^2-type
bonding. We predict three bare surfaces with lower energies than the open-ring
(10-10) surface observed at the interface, which indicate that
non-stoichiometry and the presence of the rare-earth oxide play crucial roles
in determining the termination of the Si3N4 matrix grains.Comment: 4 Pages, 4 Figures, 1 tabl
A Quasiperiodic Gibbons--Hawking Metric and Spacetime Foam
We present a quasiperiodic self-dual metric of the Gibbons--Hawking type with
one gravitational instanton per spacetime cell. The solution, based on an
adaptation of Weierstrassian and functions to three
dimensions, conforms to a definition of spacetime foam given by Hawking.Comment: 14 pages, Late
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