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According to Bacetti (1998) tooth rotation is defined as observable mesiolingual or distolingual intra-alveolar displacement of the tooth around its longitudinal axis.1 Tooth rotations cause difficulty in finishing fixed orthodontic treatment. In Begg’s technique rotation springs are used to correct tooth rotations. These springs are engaged into the vertical slot of the bracket. In case of preadjusted edgewise technique and edgewise technique brackets doesn’t have a vertical slot. So alternative methods are used to correct tooth rotations.2 Various methods include engaging NiTi arch wire into the bracket slot, off centering the bracket, using rotation wedges, creating a couple on the rotated tooth, by using ligature ties.3 The purpose of this case series is to discuss the biomechanics involved in rotation correction using bracket offsetting and couple. Keywords: Couple, Bracket offsetting.

Introduction: The purpose of these case reports was to evaluate the thickness of the lower anterior alveolar trough in patients with tongue thrusting habit. Materials and Methods: Lateral cephalogram and CBCT was evaluated in these patients. Result: Both lateral cephalogram and CBCT confirmed reduced thickness of anterior trough in patients with tongue thrust habit. Conclusion: Depending on the thickness of the alveolar bone, the extend of lower incisor retraction could be evaluated. Keywords: Tongue, alveolar trough, Lateral cephalogram, CBCT.

The fixed lingual arches that are used for mandibular molar uprighting works in two dimensions, whereas the 3D lingual arch works in all the three dimensions. The 3D lingual arch was fabricated from a 0.028 "round S.S wire with parts consisting of an adaptor, activator, friction lock and extender. The friction lock was inserted into the vertical stubs welded on the molar bands of the lingually tipped molar. They provided greater stability and anchorage to the molars. Up righting of the lingually tipped mandibular molars was attained within one month after insertion of the Wilson's 3D lingual arch. Correction was attained in all three dimensions with a buccal crown torque and lingual root torque. Levelling and alignment of the anterior segment was also attained by this multipurpose modular appliance. The 3D lingual arch enabled the clinician to set up a more positive anchorage for a greater variety of treatment applications than earlier lingual arches. Quality treatment results were attained with less span of time and were cost effective.

This paper demonstrates the biomechanics used in orthodontics for the labial movement of a lingually blocked out tooth. Alignment of a lingually blocked out tooth with proper expression of labial root torque is often challenging as creation of a moment to force ratio of higher than 10:1 is difficult in the oral environment. This high moment to force ratio is needed to move the root of the tooth ahead of the crown. Here, we demonstrate a very simple spring that can torque the root ahead of crown and align the teeth to the remaining dentition by maintaining the moment to force ratio in a more than 10:1 value. This will move the root ahead of crown into the medullary area and the crown follows the root into a good alignment.

Certain malocclusions have to be treated at an early age to avoid surgeries for the correction in the future. Introduction of functional appliances has reduced the elimination and correction of skeletal as well as dental discrepancies. Proper case selection taking into consideration skeletal and dental age with the use of various diagnostic aids helps us to identify and treat the malocclusions before it is too late. In this case series, we report three patients with skeletal jaw malrelationship treated with functional and orthopaedic appliances.

An analysis of Ir-192 source distribution using the Monte Carlo method and radiochromic film experiments for endovascular brachytherapy is presented. Three different source possibilities, namely, mHDR Ir-192 sources with 5 mm and 2.5 mm step sizes and Ir-192 seed sources with 1 mm air gap are investigated to obtain uniform radial dose distribution throughout the treatment area. From this study, it is inferred that mHDR Ir-192 sources with 2.5 mm step size are effective for getting dose uniformity. Hence, different restenosis geometries, namely, linear, dumb bell and hairpin, are simulated with 2.5 mm step size, 15 mHDR Ir-192 sources using the Monte Carlo technique and the results are compared experimentally by using radiochromic films. The results from both methods agreed to within 7%. Further, it is also inferred that for the dosimetry of endovascular brachytherapy, the film dosimetry may be considered adequate, even if the film calibration is time consuming and requires adequate dosimetric procedures.

The present work is primarily focused on the estimation of relative dose distribution and effective transmission around a shielded vaginal cylinder with an Ir 192 source using the Monte Carlo technique. The MCNP4B code was used to evaluate the dose distribution around a tungsten shielded vaginal cylinder as a function of thickness and angular shielding. The dose distribution and effective transmission of Ir 192 by 0.8 cm thickness tungsten were also compared with that for gold and lead.Dose distributions were evaluated for different distances starting from 1.35 cm to 10.15 cm from the center of the cylinder. Dose distributions were also evaluated sequentially from 0 ° to 180 ° for every 5 ° interval. Studies show that all the shielding material at 0.8 cm thickness contribute tolerable doses to normal tissues and also protect the critical organs such as the rectum and bladder. However, the computed dose values are in good agreement with the reported experimental values. It was also inferred that the higher the shielding angles, the more the protection of the surrounding tissues. Among the three shielding materials, gold has been observed to have the highest attenuation and hence contribute lowest transmission in the shielded region. Depending upon the shielding angle and thickness, it is possible to predict the dose distribution using the MCNP4B code. In order to deliver the higher dose to the unshielded region, lead may be considered as the shielding material and further it is highly economic over other materials.

Monte Carlo modeling of the Kalpakkam Mini Reactor (KAMINI) has been carried out for the first time by using Monte Carlo code (MCNP4A) and continuous energy cross-sections. The safety control plate (SCP) drop experiment is simulated and the computed integral worth of the SCPs is compared with the measured value. The measured axial neutron flux profile and foil reaction rates in one of the in-core irradiation location and the foil reaction rates at the west beam port are also compared with the predicted results. The agreement between measurements and calculations is quite satisfactory. It is confirmed from the calculation and measurement that the north thimble is having nearly 10–20% higher neutron flux as compared to the south thimble depending on the exact elevation.

KAMINI is the Kalpakkam Mini Reactor and its main purpose is to cater to the experimental needs and for neutron radiography. It is a water-cooled reactor with 233 U as the fissile material. The reactor has three neutron beam ports for experimental needs, which are made of graded cylindrical aluminium channel. All the beam ports start from the core, pierce the biological shield and are 2 m long. The shield structure optimisation studies for the beam port towards the west side of the reactor are presented here. The diameter of the west beam channel at the core centre is 54 mm and at the other end is 250 mm. The west beam tube opening is 530 mm below the floor level and hence the pit housing the experimental cavity is below the floor level with dimensions 2 m × 2.5 m × 1.3 m. The beam tube opening into the experimental cavity serves as the neutron source for radiation physics experiments and is assumed as a surface source in the calculations. Rough estimate of the shield design is made based on the literature on dose-equivalent index transmission through concrete for average neutron energy of 1.5 MeV. Detailed radiation transport calculations are performed using Monte Carlo neutral particle transport code (MCNP) to optimise the shield design. Neutron and capture gamma dose rates at the accessible areas are estimated. The contribution of prompt fission gamma rays is found to be negligible compared to the dose rates due to capture gamma rays. The details of the optimised shield structure proposed for the west beam port are as follows. Fixed concrete shields of thickness 650 mm on the lateral sides and a composite shield (500 mm paraffin and 50 mm concrete) in the front side at a distance of 1 m from the beam tube opening are recommended inside the experimental pit. During reactor operation, a composite mobile shield (500 mm paraffin and 500 mm concrete) closes the experimental cavity at the floor level. Fixed concrete shields are recommended to close the pit fully. The shield structure proposed increases the experimental cavity volume from 0.2 to 1.4 m 3 with the dose levels at the accessible areas less than one μSv/h. The MCNP computed neutron and gamma dose rates are compared with the measured values with the existing shield structure to verify the source term used.

A graphical user-friendly interface is developed in Visual Basic (VB)-6 to view the variation of neutron and photon interaction cross-sections of different isotopes as a function of energy. VB subroutines developed read the binary data files of cross-sections created in MCNP-ACE (Briesmeister, J.F., 1993. MCNP- a general purpose Monte Carlo N-Particle Transport code. Version 4A. LANL, USA), ANISN-DLC (Engle W.W. Jr., 1967, A User's Manual for ANISN, K-1693; ORNL, 1974. 100 group neutron cross section data based on ENDF/B-III. Oak Ridge National Laboratory, USA) and KENO-AMPX (Petrie, L.M., Landers, N.F., 1984 KENO-Va- An Improved Monte Carlo Criticality Program with Super Grouping. RSICC-CCC-548, USA) formats using LAHEY-77 Fortran Compiler. The information on isotopes present in each library will be displayed with the help of database files prepared using Micro-Soft ACESS. The cross-section data can be viewed in different presentation styles namely, line graphs, bar graphs, histograms etc., with different color and symbol options. The cross-section plots generated can be saved as Bit-Map file to embed in any other text files. This software enables inter comparison of cross-sections from different type of libraries for isotopes as well as mixtures. Provision is made to view the cross-sections for nuclear reactions such as (n,γ), (n,f), (n,α), etc. The software can be obtained from Radiation Safety Information and Computational Centre (RSICC), ORNL, USA with the code package identification number PSR-514. The software package needs a hard disk space of about 80 MB when installed and works in WINDOWS-95/98/2000 operating systems.

Nearly all chemical, pharmaceutical, food processing and bio medical industries require large volumes of liquid transfer. With automation technology, the capacity, easiness and efficiency of liquid transferring systems has been greatly enhanced. Precision and accuracy in the volume of liquid dispensed plays a vital role in determining the overall efficiency of the industrial processes. An automated precise liquid transferring system targets replacement of the conventional erratic flow meters and highly expensive flow sensors used in the industries. This non-contact system enhances the overall efficiency of liquid transferring process in a very cost effective manner. The system control was implemented through Unitronics PLC and the noncontact mechanism of liquid dispensing was designed with the help of solenoid valves, relays, FRL and various other devices. The liquid was initially pressurized for a pre-defined time and the precisely dispensed by regulating the opening and closing time of solenoid valves. Provision for liquid transfer to demanded mixture tank is also provided. Flow rate of the liquid and the on- off time for solenoid determines the volume of liquid transferred. Experiment carried out for different volumes of liquid showed an accuracy of 1–2 gm. Using the PLC control and automation, the time required for the entire process of liquid dispensing was brought down to few seconds irrespective of the volume of the liquid dispensed.

KAMINI is the Kalpakkam Mini Reactor, and its main purpose is to cater to experimental needs and for neutron radiography. It is a water-cooled reactor with 233U as the fissile material. Using the M...

A large variety and amount of data of safety significance are routinely collected during the operation of a nuclear power plant (NPP). The data collected in the area of radiological protection have...

As per TG-43 dose calculation formalism, it is essential to obtain various dosimetric parameters such as the air-kerma strength, dose rate constant, radial dose function, and anisotropy function, as they account for accurate determination of dose rate distribution around brachytherapy sources. Most of the available reported Monte Carlo simulations were performed in liquid water phantoms with a bounded region of 30-cm diameter. In this context, an attempt was made to report the dosimetric parameters for various commercially available pulsed-dose rate (PDR) and high-dose rate (HDR) sources under unbounded phantom conditions, as the data may be used as input to treatment planning systems (TPSs) for quality control assistance. The air-kerma strength per unit activity, S(k)/A, was computed for various Iridium-192 ((192)Ir) sources in dry air medium. The air-kerma strength and dose rate constant for old PDR is (9.77 +/- 0.03) 10(-8) U/Bq and 1.124 +/- 0.001 cGyh(-1)U(-1); for new PDR, the values are (9.96 +/- 0.03) 10(-8) U/Bq and 1.124 +/- 0.001 cGyh(-1)U(-1); for old MHDR, the values are (9.80 +/- 0.01) 10(-8) U/Bq and 1.115 +/- 0.001 cGyh(-1)U(-1); for new MHDR, (9.80 +/- 0.01) 10(-8) U/Bq and 1.112 +/- 0.001cGyh(-1)U(-1); for old VHDR, the values are (10.32 +/- 0.01) 10(-8) U/Bq and 1.035 +/- 0.002 cGyh(-1)U(-1); for new VHDR, the values are (10.34 +/- 0.02) 10(-8) U/Bq and 1.096 +/- 0.001 cGyh(-1)U(-1). The computed radial dose function values and anisotropy function values are also in good agreement with available data.

The present work is primarily focused on the estimation of relative dose distribution and effective transmission around a shielded vaginal cylinder with an 192Ir source using the Monte Carlo technique. The MCNP4B code was used to evaluate the dose distribution around a tungsten shielded vaginal cylinder as a function of thickness and angular shielding. The dose distribution and effective transmission of 192Ir by 0.8 cm thickness tungsten were also compared with that for gold and lead. Dose distributions were evaluated for different distances starting from 1.35 cm to 10.15 cm from the center of the cylinder. Dose distributions were also evaluated sequentially from 0 degrees to 180 degrees for every 5 degrees interval. Studies show that all the shielding material at 0.8 cm thickness contribute tolerable doses to normal tissues and also protect the critical organs such as the rectum and bladder. However, the computed dose values are in good agreement with the reported experimental values. It was also inferred that the higher the shielding angles, the more the protection of the surrounding tissues. Among the three shielding materials, gold has been observed to have the highest attenuation and hence contribute lowest transmission in the shielded region. Depending upon the shielding angle and thickness, it is possible to predict the dose distribution using the MCNP4B code. In order to deliver the higher dose to the unshielded region, lead may be considered as the shielding material and further it is highly economic over other materials.

The analysis of the x-ray spectrum obtained in electron cyclotron resonance (ECR) x-ray source is carried out. Assuming single-particle motion, the electron acceleration and its final energy are calculated for TE111 cylindrical cavity field and uniform external dc magnetic field. In the calculation, initial coordinates of 40 000 electrons were uniformly selected over the central plane of the cavity using random number generator. The final energy of each electron when it hits the wall is stored and the electron energy distribution is obtained. Using the general purpose Monte Carlo N-particle transport code version 4A, the geometry of the ECR x-ray source is modeled. The x-ray energy spectrum is calculated for the geometry model and the numerically calculated electron energy distribution. The calculated x-ray spectrum is compared with the experimentally measured x-ray spectrum.