3,508 research outputs found
Non-Syndromic Unilateralsupplemental Maxillary Central Incisor: A Case Report
Background: Supernumerary teeth are developmental anomaly. There are various theories explaining their occurrence. Maxilla is more commonly affected and males have higher predilection than females for having supernumerary teeth.Case Details: The present case is presented with three permanent central incisors, all of them with normal morphology. On clinical and radiographic examination, it was identified as a case of nonsyndromic unilateral left supplemental maxillary central incisor. Treatment plan involved extraction of the supplemental tooth followed by orthodontic treatment to correct the malalignment of the teeth.Conclusion: The presence of supplemental teeth of normal morphology is quite a rare condition and are commonly associated with various syndromes but, in rare cases, they also exists as non-syndromic forms. Supernumerary teeth can cause aesthetic or functional problems, especially when situated in the maxillary anterior region. Complications related to the phenomenon can be minimized by early detection and by carrying out a comprehensive treatment protocol.Keywords: supplemental, central inciso
Growth and characterization of crystals for IR detectors and second harmonic gereration devices
Two types of materials, L-arginine phosphate (LAP) and doped triglycine sulfate (TGS), are examined for their growth characteristics and relevant properties for second harmonic generation and IR detector applications, respectively
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Sex-Specific Effects of a Wartime-Like Radiation Exposure on Cognitive Function.
Evaluating the risk for central nervous system (CNS) effects after whole-body or partial-body irradiation presents challenges due in part to the varied exposure scenarios in the context of occupational, accidental or wartime releases. Risk estimations are further complicated by the fact that robust changes in brain function are unlikely to manifest until significantly late post exposure times. Collectively, the current data regarding CNS radiation risk are conflicting in humans and a survey of the animal model data shows that it is similarly inconsistent. Due to the sparseness of such data, the current study was conducted using male and female mice to evaluate the brain for the delayed effects of a 2 Gy whole-body exposure to c rays starting six months postirradiation. Behavioral testing indicated sex-specific differences in the induction of anxiety-like behaviors and in the ability to abolish fear memories. Molecular analyses showed alterations in post-synaptic protein levels that might affect synaptic plasticity and increased levels of global DNA methylation, suggesting a potential epigenetic mechanism that might contribute to radiation-induced cognitive dysfunction. These data add to the understanding of the CNS response to whole-body irradiation and may lead to improved risk assessment and provide guidance in the development of effective radiation countermeasures to protect military personnel and civilians alike
Te covered Si(001): a variable surface reconstruction
At a given temperature, clean and adatom covered silicon surfaces usually
exhibit well-defined reconstruction patterns. Our finite temperature ab-initio
molecular dynamics calculations show that the tellurium covered Si(001) surface
is an exception. Soft longitudinal modes of surface phonons due to the strongly
anharmonic potential of the bridged tellurium atoms prevent the reconstruction
structure from attaining any permanent, two dimensional periodic geometry. This
explains why experiments attempting to find a definite model for the
reconstruction have reached conflicting conclusions.Comment: 4 pages, 3 gif figure
Measuring the W-t-b Interaction at the ILC
The large top quark mass suggests that the top plays a pivotal role in
Electroweak symmetry-breaking dynamics and, as a result, may have modified
couplings to Electroweak bosons. Hadron colliders can provide measurements of
these couplings at the ~10% level, and one of the early expected triumphs of
the International Linear Collider is to reduce these uncertainties to the per
cent level. In this article, we propose the first direct measurement of the
Standard Model W-t-b coupling at the ILC, from measurements of t tbar-like
signals below the t tbar production threshold. We estimate that the ILC with
100 fb^{-1} can measure a combination of the coupling and top width to high
precision, and when combined with a direct measurement of the top width from
the above-threshold scan, results in a model-independent measurement of the
W-t-b interaction of the order of ~ 3%
Pentagonal nanowires: a first-principles study of atomic and electronic structure
We performed an extensive first-principles study of nanowires in various
pentagonal structures by using pseudopotential plane wave method within the
density functional theory. Our results show that nanowires of different types
of elements, such as alkali, simple, transition and noble metals and inert gas
atoms, have a stable structure made from staggered pentagons with a linear
chain perpendicular to the planes of the pentagons and passing through their
centers. This structure exhibits bond angles close to those in the icosahedral
structure. However, silicon is found to be energetically more favorable in the
eclipsed pentagonal structure. These quasi one dimensional pentagonal nanowires
have higher cohesive energies than many other one dimensional structures and
hence may be realized experimentally. The effect of magnetic state are examined
by spin-polarized calculations. The origin of the stability are discussed by
examining optimized structural parameters, charge density and electronic band
structure, and by using analysis based on the empirical Lennard-Jones type
interaction. Electronic band structure of pentagonal wires of different
elements are discussed and their effects on quantum ballistic conductance are
mentioned. It is found that the pentagonal wire of silicon exhibits metallic
band structure.Comment: 4 figures, accepted for publication in Phys. Rev.
Structure of aluminum atomic chains
First-principles density functional calculations reveal that aluminum can
form planar chains in zigzag and ladder structures. The most stable one has
equilateral triangular geometry with four nearest neighbors; the other stable
zigzag structure has wide bond angle and allows for two nearest neighbors. An
intermediary structure has the ladder geometry and is formed by two strands.
All these planar geometries are, however, more favored energetically than the
linear chain. We found that by going from bulk to a chain the character of
bonding changes and acquires directionality. The conductance of zigzag and
linear chains is 4e^2/h under ideal ballistic conditions.Comment: modified detailed version, one new structure added, 4 figures,
modified figure1, 1 tabl
Cocaine-Induced Hepatonephrotoxicity: A Case Report
Hepatotoxicity due to cocaine has been well described in animal models. There are few reports on cocaine-induced hepatic injury in humans; however, its link to rhabdomyolysis and renal failure is better known. We report a case of reversible acute hepatonephrotoxicity associated with recreational cocaine use. The proposed mechanisms responsible for its hepatic and renal toxicity are reviewed
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