718 research outputs found
Alveolar exostosis – revisited: A narrative review of the literature
AbstractAn exostosis is a localized, peripheral overgrowth of bone of unknown etiology of benign nature. It may be a nodular, flat or pedunculated protuberance located on the alveolar surfaces of the jawbones. The etiology of oral bony exostosis is still not clear. Racial, autosomal dominant factors, dental attrition, and even nutritional factors have been suggested as having an influence. In the jaws, depending on the anatomic location they are named as torus palatinus (TP), torus mandibularis (TM), or buccal bone exostoses (BBE). The clinical importance of exostosis lies in surgical removal of these to permit proper flap adaptation, most importantly in the posterior maxilla, and to the potential use of the mandibular and palatal tori as sources of autogenous cortical bone for grafting
Probing photospheric magnetic fields with new spectral line pairs
The magnetic line ratio (MLR) method has been extensively used in the
measurement of photospheric magnetic field strength. It was devised for the
neutral iron line pair at 5247.1 A and 5250.2 A (5250 A pair). Other line pairs
as well-suited as this pair been have not been reported in the literature. The
aim of the present work is to identify new line pairs useful for the MLR
technique and to test their reliability. We use a three dimensional
magnetohydrodynamic (MHD) simulation representing the quiet Sun atmosphere to
synthesize the Stokes profiles. Then, we apply the MLR technique to the Stokes
V profiles to recover the fields in the MHD cube both, at original resolution
and after degrading with a point spread function. In both these cases, we aim
to empirically represent the field strengths returned by the MLR method in
terms of the field strengths in the MHD cube. We have identified two new line
pairs that are very well adapted to be used for MLR measurements. The first
pair is in the visible, Fe I 6820 A - 6842 A (whose intensity profiles have
earlier been used to measure stellar magnetic fields), and the other is in the
infrared (IR), Fe I 15534 A - 15542 A. The lines in these pairs reproduce the
magnetic fields in the MHD cube rather well, partially better than the original
5250 A pair. The newly identified line pairs complement the old pairs. The
lines in the new IR pair, due to their higher Zeeman sensitivity, are ideal for
the measurement of weak fields. The new visible pair works best above 300 G.
The new IR pair, due to its large Stokes V signal samples more fields in the
MHD cube than the old IR pair at m, even in the presence of noise,
and hence likely also on the real Sun. Owing to their low formation heights
(100-200 km above tau_5000=1), both the new line pairs are well suited for
probing magnetic fields in the lower photosphere.Comment: Accepted for publication in Astronomy & Astrophysic
Random Network Behaviour of Protein Structures
Geometric and structural constraints greatly restrict the selection of folds
adapted by protein backbones, and yet, folded proteins show an astounding
diversity in functionality. For structure to have any bearing on function, it
is thus imperative that, apart from the protein backbone, other tunable degrees
of freedom be accountable. Here, we focus on side-chain interactions, which
non-covalently link amino acids in folded proteins to form a network structure.
At a coarse-grained level, we show that the network conforms remarkably well to
realizations of random graphs and displays associated percolation behavior.
Thus, within the rigid framework of the protein backbone that restricts the
structure space, the side-chain interactions exhibit an element of randomness,
which account for the functional flexibility and diversity shown by proteins.
However, at a finer level, the network exhibits deviations from these random
graphs which, as we demonstrate for a few specific examples, reflect the
intrinsic uniqueness in the structure and stability, and perhaps specificity in
the functioning of biological proteins.Comment: Expanded version available in Molecular BioSystem
Health & Habits: Back to the Old Age - Yoga
Health & Habits: Back to the Old Age - Yog
A New Low Complexity Uniform Filter Bank Based on the Improved Coefficient Decimation Method
In this paper, we propose a new uniform filter bank (FB) based on the improved coefficient decimation method (ICDM). In the proposed FB’s design, the ICDM is used to obtain different multi-band frequency responses using a single lowpass prototype filter. The desired subbands are individually obtained from these multi-band frequency responses by using low order frequency response masking filters and their corresponding ICDM output frequency responses. We show that the proposed FB is a very low complexity alternative to the other FBs in literature, especially the widely used discrete Fourier transform based FB (DFTFB) and the CDM based FB (CDFB). The proposed FB can have a higher number of subbands with twice the center frequency resolution when compared with the CDFB and DFTFB. Design example and implementation results show that our FB achieves 86.59% and 58.84% reductions in resource utilizations and 76.95% and 47.09% reductions in power consumptions when compared with the DFTFB and CDFB respectively
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