Anthropometric Analysis of Indian Faces: A Systematic Review.

Objective: Facial anthropometric data vary significantly within the Indian population due to the racial, ethnic and geographic diversity. The anthropometric data of a given ethnic community may not match the other due to diverse ethnic variations, and hence, this study is intended to review the facial anthropometric data pertaining to the diverse Indian populace through a systematic literature survey. Materials and Method: An electronic search done on Medline, Embase and Central databases was utilized to conduct a systematic review of literature. The available data were analyzed based on the various esthetic subunits of the face. The following inclusion criteria were considered: (1) studies depicting the anthropometric data of any ethnic group identified as belonging to India, (2) studies originating from Indian subcontinent, (3) studies which included data of male and female subjects separately and (4) articles in English language only. The following exclusion criteria were considered: (1) atudies conducted on participants with severe malocclusion, developmental craniofacial anomalies, post-traumatic facial deformities or with a history of previous craniofacial or cosmetic surgery, (2) studies which did not specify the anthropometric landmarks used to obtain the measurements, (3) studies in which the statistical analysis was not provided, or if data were grouped across genders and (4) editorials, commentaries, case reports, systematic reviews, meta-analyses and articles not available in English language. Results: Twenty-one articles met the inclusion criteria. Majority of the Indians, particularly men, seem to have a mesoproscopic facial phenotype. The vertical and horizontal facial dimensions of the Indian male are comparably larger than the Indian female. There is sexual dimorphism among the Indian population with regard to the upper and lower thirds of the face, with little or no gender difference as regards the middle third of the face. It was observed that the nasal dimensions of the Indian race were not compatible with that of the occidental, oriental or the western race. The overall facial structure and the upper half of the face were critical in determining facial attractiveness in Indian males while the lower half of the face and the mandibular contour were critical in determining facial attractiveness in females. Conclusion: It is observed that there is a paucity of facial anthropometric data for the Indian population considering the ethnic, racial and geographic diversity. Since the prevalence of craniofacial anomalies and dentofacial deformities in India is high and thus the scope for corrective surgery, it is important to compile baseline facial anthropometric data based on the ethnic diversity of the Indian population.

Is There a Need for Greater Emphasis on Clinical Facial Analysis than Cephalometrics & 3D Software Solutions in the Diagnosis and Treatment Planning of Patients with Dentofacial Deformities?

Purpose: This study is designed to evaluate the need for a greater emphasis on clinical facial analysis over cephalometrics in the diagnosis and treatment planning of patients with dentofacial deformities. Materials and Method: A predetermined questionnaire study was designed to get the thought process of surgeons and consultants involved in orthognathic surgery from various parts of southern India. Two hundred and twenty-eight maxillofacial consultants were involved in the survey. Demographic information, type of professional practice, preferred tool in the diagnosis & treatment planning: Cephalometrics or 3D software solutions and flaw in the available tools were evaluated. Results: The results of this study revealed that only 36.8% of the consultants felt that cephalometrics is the prime tool and 73.3% of the consultants felt that 3D software solutions were superior to cephalometrics in the diagnosis and treatment planning of patients with dentofacial deformities. However, 46% of the consultants preferred facial analysis as the prime tool with cephalometrics as an adjunct. Pertaining to the clinical outcome of their treated cases of dentofacial deformities, 61.8% of the consultants felt the need to address additional cosmetic issues following an orthognathic procedure. It was observed that 92.1% of the participants felt the need for greater emphasis on clinical facial analysis than cephalometrics. Conclusion: Human faces should always be evaluated taking into consideration the various esthetic units of the face. Performing corrective jaw surgery merely based on cephalometric values inevitably fails to address the various other innate imbalances of the face. Hence, cephalometric data should only be considered as an adjunct to clinical judgment in the diagnosis and treatment planning of dentofacial deformities.

Patient Satisfaction Following Orthognathic Surgery: A Systematic Review.

Objective: This study is intended to review data pertaining to patient satisfaction following orthognathic surgery through a systematic literature survey. Methods and Materials: An electronic search was done on Medline, EMBASE and CENTRAL databases. The inclusion criteria considered were as follows: (1) assessment of patients' satisfaction, (2) one-stage orthognathic surgery, and (3) follow-up period of 8 weeks or more in English literature. The exclusion criteria considered were as follows: (1) presence of craniofacial syndromes, cleft lip and palate or traumatic injuries, (2) previous facial surgery, and (3) psychological problems before surgery. The data were extracted and analyzed under three categories: function, esthetics and overall satisfaction. Results: Eighteen studies met the inclusion criteria. Esthetic and function were improved in majority of patients; however, it was not possible to assess the overall satisfaction levels statistically. Overall satisfaction analysis revealed that 70-87% of patients were satisfied, while nearly 15% of patients were dissatisfied with the treatment outcome. Conclusion: Most of the patients were satisfied with the surgical outcome. However, satisfaction seemed to be multifactorial and it was not possible to predict satisfaction prior to the surgery.

Ultra-thin polarization independent broadband terahertz metamaterial absorber.

In this work, we present the design of a polarization independent broadband absorber in the terahertz (THz) frequency range using a metasurface resonator. The absorber comprises of three layers, of which, the top layer is made of a vanadium dioxide (VO2) resonator with an electrical conductivity of σ = 200000 S/m; the bottom layer consists of a planar layer made of gold metal, and a dielectric layer is sandwiched between these two layers. The optimized absorber exhibits absorption greater than 90% from 2.54-5.54 THz. Thus, the corresponding bandwidth of the designed absorber is 3 THz. Further, the thermal tunable absorption and reflection spectra have been analyzed by varying the electrical conductivity of VO2. The impact of the various geometrical parameters on the absorption characteristics has also been assessed. The physics of generation of broadband absorption of the proposed device has been explored using field analysis. Finally, the absorption characteristics of the unit cell has been studied for various incident and polarization angles.

Highly Sensitive Localized Surface Plasmon Polariton Based D-Type Twin-Hole Photonic Crystal Fiber Microbiosensor: Enhanced Scheme for SERS Reinforcement.

The emerging development of sensing technology initiates innovative sensors achieving low-cost to facilitate practical realization. An interesting crush of the work is to propose a simple structural sensor and to analyze the different schemes of the metal coating by stimulated emission of Raman scattering (SERS) intensification. For the first time, we propose a simple geometrical photonic crystal fiber refractive index based sensor (PCF-RIBS) with three different Schemes A, B, and C, i.e., gold (A) layer-coated surface plasmon resonance (SPR) based D-type PCF-RIBS; Au with titanium-di-oxide (TiO2) layer-coated SPR D-type PCF-RIBS; and Au + TiO2 grating-coated localized surface plasmon resonance (LSPR) D-type PCF-RIBS. Characterizing the three different Schemes A, B, and C using finite element method simulation shows, a maximum wavelength sensitivity of 48,000 nm/RIU, 52,000 nm/RIU and 75,000 nm/RIU, respectively, for a wide range of analyte-refractive index from 1.33 to 1.45 and operates in the wavelength range from 500-2000 nm. Of all the Schemes, Scheme C is found to excite a relatively larger number of surface-plasmons. Eventually, it exhibits improved sensing performances compared to SPR based Schemes A and B. Consequently, it would turn out to be an appropriate candidate to detect a broad range of biological and chemical sample detection.

Chirped self-similar solitary waves for the generalized nonlinear Schrödinger equation with distributed two-power-law nonlinearities.

We investigate the propagation characteristics of the chirped self-similar solitary waves in non-Kerr nonlinear media within the framework of the generalized nonlinear Schrödinger equation with distributed dispersion, two-power-law nonlinearities, and gain or loss. This model contains many special types of nonlinear equations that appear in various branches of contemporary physics. We extend the self-similar analysis presented for searching chirped self-similar structures of the cubic model to a more general problem involving two nonlinear terms of arbitrary power. A variety of exact linearly chirped localized solutions with interesting properties are derived in the presence of all physical effects. The solutions comprise bright, kink and antikink, and algebraic solitary wave solutions, illustrating the potentially rich set of self-similar pulses of the model. It is shown that these optical pulses possess a linear chirp that leads to efficient compression or amplification, and thus are particularly useful in the design of optical fiber amplifiers, optical pulse compressors, and solitary wave based communication links. Finally, the stability of the self-similar solutions is discussed numerically under finite initial perturbations.

Dosimetric Effect of Rotational Setup Errors in Single-Isocenter Volumetric-Modulated Arc Therapy of Multiple Brain Metastases.

AIM: The aim of this study is to investigate the dosimetric effects of rotational uncertainties in patient positioning on target coverage in stereotactic radiosurgery (SRS) of multiple brain metastases using single isocenter volumetric modulated arc therapy (VMAT). MATERIALS AND METHODS: Ten SRS cases with multiple brain metastases (2-8) planned with single isocenter non-coplanar VMAT technique were investigated in this study. Pitch, yaw and roll displacements of 1, 3 and 5° were simulated about isocenter along each axes and nine plans were obtained for each case. Gross tumor volume (GTV) coverage obtained on simulated plans were compared with the original plan on four metrics of mean dose (Dmean), minimum dose to GTV (Dmin), dose to 95% of GTV (D95) and the volume covered by the 95% of the prescribed dose (V95). RESULTS: At 1° rotation about 4% of the PTV had V95 and D95 values <95%. The minimum dose obtained across all PTV was 85.1% and there was not much change in the mean dose values obtained. The PTV volume which had V95 and D95 values <95% were in the range of 0.05 - 0.07cc and at a radial distance of 6.2 cm - 7.2 cm. At 3° rotation almost 50% of the PTV had V95 and D95 values <95%. The minimum dose obtained across all PTV was 48.3% and the mean dose reduced to as low as 78.8%. At 5° rotation almost 74% of the PTV had V95 and D95 values <95%. The minimum dose obtained across all PTV was 21.2% and the mean dose reduced to as low as 49.2%. CONCLUSION: Our results indicate that correcting rotational uncertainties is critical in single-isocenter, multi-target SRS. For rotational deviations, radial distance of the target from isocenter along the respective axis has a strong influence on target coverage. For rotational setup deviation at a given radial distance larger targets tend to have lesser geometric miss compared to smaller targets. Mathematical model for spherical targets can be used to estimate V95 for given rotational errors.

Study of Variation in Dose Calculation Accuracy Between kV Cone-Beam Computed Tomography and kV fan-Beam Computed Tomography.

Cone-beam computed tomography (CBCT) images are presently used for geometric verification for daily patient positioning. In this work, we have compared the images of CBCT with the images of conventional fan beam CT (FBCT) in terms of image quality and Hounsfield units (HUs). We also compared the dose calculated using CBCT with that of FBCT. Homogenous RW3 plates and Catphan phantom were scanned by FBCT and CBCT. In RW3 and Catphan phantom, percentage depth dose (PDD), profiles, isodose distributions (for intensity modulated radiotherapy plans), and calculated dose volume histograms were compared. The HU difference was within ± 20 HU (central region) and ± 30 HU (peripheral region) for homogeneous RW3 plates. In the Catphan phantom, the difference in HU was ± 20 HU in the central area and peripheral areas. The HU differences were within ± 30 HU for all HU ranges starting from -1000 to 990 in phantom and patient images. In treatment plans done with simple symmetric and asymmetric fields, dose difference (DD) between CBCT plan and FBCT plan was within 1.2% for both phantoms. In intensity modulated radiotherapy (IMRT) treatment plans, for different target volumes, the difference was <2%. This feasibility study investigated HU variation and dose calculation accuracy between FBCT and CBCT based planning and has validated inverse planning algorithms with CBCT. In our study, we observed a larger deviation of HU values in the peripheral region compared to the central region. This is due to the ring artifact and scatter contribution which may prevent the use of CBCT as the primary imaging modality for radiotherapy treatment planning. The reconstruction algorithm needs to be modified further for improving the image quality and accuracy in HU values. However, our study with TG-119 and intensity modulated radiotherapy test targets shows that CBCT can be used for adaptive replanning as the recalculation of dose with the anisotropic analytical algorithm is in full accord with conventional planning CT except in the build-up regions. Patient images with CBCT have to be carefully analyzed for any artifacts before using them for such dose calculations.

Designing photonic quasi-crystal fibers of various folds: onto optimization of efficiency and bandwidth of second harmonic generation.

We design photonic quasi-crystal fibers (PQFs) of six-, eight-, ten-, and twelve-folds for determining the optimized efficiency as well as the bandwidth of second harmonic generation (SHG). We report a maximum SHG relative efficiency of 941.36% W⁻¹ cm⁻² for a twelve-fold PQF of 2 µm pitch. The detailed numerical results reveal that, while the relative efficiency increases appreciably, the phase-matching bandwidth increases marginally, as and when the number of folds increases. As the primary interest of this work is to enhance the relative efficiency, we focus our analysis with a twelve-fold PQF for which the efficiency turns a maximum. In line with the practical feasibility of poling, we keep the pitch at 7 µm and report an optimized relative efficiency and phase-matching bandwidth as 95.28% W⁻¹ cm⁻² and 50.51 nm.cm, respectively.

Periodic waves in fiber Bragg gratings.

We construct two families of exact periodic solutions to the standard model of fiber Bragg grating (FBG) with Kerr nonlinearity. The solutions are named "sn" and "cn" waves, according to the elliptic functions used in their analytical representation. The sn wave exists only inside the FBG's spectral bandgap, while waves of the cn type may only exist at negative frequencies (omega<0), both inside and outside the bandgap. In the long-wave limit, the sn and cn families recover, respectively, the ordinary gap solitons, and (unstable) antidark and dark solitons. Stability of the periodic solutions is checked by direct numerical simulations and, in the case of the sn family, also through the calculation of instability growth rates for small perturbations. Although, rigorously speaking, all periodic solutions are unstable, a subfamily of practically stable sn waves, with a sufficiently large spatial period and omega>0, is identified. However, the sn waves with omega<0, as well as all cn solutions, are strongly unstable.

Generation of Bragg solitons through modulation instability in a Bragg grating structure.

In this article, we consider the continuous wave (cw) propagation through the nonlinear periodic structure that consists of alternating layers of both positive and negative Kerr coefficients along the propagation direction. We investigate the modulational instability (MI) conditions required for the generation of ultrashort pulses for the nonlinearity management system. We study the occurrence of MI at the top and bottom edges of the photonic band gap (PBG) where the forward and backward propagating waves are strongly coupled because of the presence of the grating structure. We also study the MI when cw is detuned from the edges of the PBG into the anomalous and normal dispersion regimes. In addition, we discuss the existence of gap solitons for the nonlinearity management system in the upper and lower branches of the dispersion curve through the MI gain spectra. We observe the generation of higher order solitons in the nonlinear periodic structure when the input power is increased beyond a certain critical level. Finally, we discuss the generation of higher order Bragg grating solitons through the intensity evolution of the forward and backward propagating fields.