Folk Method Analysis (Sixth Method – a local device)

Warhadpande, M. (2021) Folk Method Analysis (Sixth Method – a local device). At Right Angles (9). pp. 51-54. ISSN 2582-187

Myths and taboos in dentistry

Background: India, a developing country, faces many challenges in rendering health needs to its countrymen. The influence of culture is seen in every discipline of health and medical practices, and dentistry is no exception. This study was performed to investigate the existence of myths and taboos in dentistry, to assess the variation of these myths across various demographic aspects and socio-economic status, to co-relate the existence of myths with the oral health of the subject and to impart education to the people regarding abolishing the myth as that will be a hindrance towards a healthy life in patients.  Methods: The study had a cross-sectional design, used a structured questionnaire and was conducted to assess the existence of dental myths and taboos and to determine its correlation with the OHIS index of the patients. Statistical analysis software SPSS V 16.0 was used. Descriptive & inferential statistical analysis was performed on categorical and continuous data. Chi-square, independent sample T tests and ANOVA test were used to compare the distribution of caries and OHI-S between different groups. P value less than 0.05 (p<0.05) was considered to be significant. Socioeconomic status was also calculated.Results: In the present study it was found that the there was almost an equal distribution of prevalence of myths in the educated as well as uneducated patients .Also the ratio of existence of myths was found higher in females as compared to males.Conclusions: Existence of myths and taboos regarding dental health has started decreasing among the urban population due to the widespread of awareness regarding dentistry.But still there is prevalence of some myths in the patients having primary education as compared to patients having secondary and tertiary education. If community is educated about proper prevention and cure, the myths relating dental concepts will vanish from the society and over all dental health status of the community will improve

Root Canal Morphology of Mandibular First Permanent Molars in an Indian Population

An in vitro study was performed to determine the number of roots, root canals per tooth, root canal configurations, and frequency of isthmi and apical deltas in mandibular first permanent molars in an Indian population. Hundred and fifty mandibular first permanent molars were collected and subjected to clearing technique. The cleared teeth were examined in a stereomicroscope under 7.5x magnifications. The canal configurations were categorized using Vertucci's classification. Overall 94.6% of the mandibular first molars had two roots, and 5.3% had extradistal roots (distolingual root). In addition, 64% of the specimens had three root canals, and 36% had four root canals. The most common canal configurations of mesial and distal roots were Vertucci type IV (54%) and type I (65.3%), respectively. Clinician should be aware of the complex root canal morphology of mandibular first molars among the Indian population before and during the root canal treatment

Lessons from proofs both false and true

Typically, it is only after a false proof has reached some absurd conclusion that one backtracks to see what went wrong. Often one learns something of interest. We wondered if we routinely miss such lessons by not analysing ‘correct’ proofs just as diligently. We decided to investigat

Initiation of sub-surface micro-cracks and white etching areas from debonding at non-metallic inclusions in wind turbine gearbox bearing

In this study, a failed planetary bearing from a wind turbine gearbox was destructively examined to investigate the initiation of micro-cracks and butterflies at non-metallic inclusions, and the effect of debonding between these inclusions and the steel matrix. The butterflies were scanned using Atomic Force Microscopy (AFM) to show the topography that could not be assessed by using other microscopy techniques. Nano-indentation was conducted across a butterfly wing and a non-metallic inclusion to measure the hardness at the interface with the steel matrix. It was found that the White Etching Areas (WEA) in the region of the butterfly wing was a damaged material that showed tearing at the debonding gap between the inclusion and steel matrix. This study highlighted the effect of debonding on the initiation of micro-cracks, WEA and inclusion cracking. A direct relationship was found between the size of inclusions and the total length of inclusions and micro-cracks or butterfly wings. The depth of the observed sub-surface damage was correlated with the sub-surface stress distribution and these results suggested that surface traction could be an important contributing factor to the subsurface damage initiation

Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

Premature failure of wind turbine gearbox bearings is an ongoing concern for industry, with sudden overload events potentially contributing towards raceway damage, significantly hindering performance. Subsurface stresses generated along a line contact cause material yielding, and a probable crack initiation site. Currently, the ability to study subsurface plastic zone evolution using non-destructive techniques is limited. Neutron Bragg edge imaging is a novel technique, allowing for two-dimensional mapping of the Bragg edge broadening parameter, indicative of bulk plastic deformation. An experiment on the ENGIN-X strain scanning instrument, at the ISIS neutron source, UK, was setup for Bragg edge transmission imaging, to measure the effect of in situ loading on the raceway of a bearing, scaled-down from a traditional wind turbine gearbox bearing. Results demonstrate a strong correlation between load and the Bragg edge width, and allow for future experimental development in studying, not only the effect of overloads on fatigue life, but also the use of neutron imaging for evaluating plastic deformation in engineering components

The minimal instruments of geometry – I

Euclid’s Elements (~300 BCE) built the edifice of (plane) Geometry using a toolkit comprising of two instruments: the ‘straight edge’ and the ‘collapsible compass’ [1]. Many centuries later (1941 CE), in Basic Geometry, George Birkhoff and Ralph Beatley provided an alternative construction of this edifice using a three-instrument toolkit which contemporary students continue to use: the ‘ruler’, the ‘compass’ and the ‘protractor’ [2]. In contrast, a few centuries before Euclid (~800 BCE), Indian vedic texts (Shulbasutras) recommended the ‘rajju’, i.e., a rope, as the lone instrument to be used for geometrical constructions

The Minimal Instruments of Geometry – II

In the first part of this article, we introduced three alternative geometrical toolkits: (a) the straight edge and collapsible compass of Euclid, (b) the ruler, compass, and protractor of Birkhoff and Beatley, and (c) the rope of the Shulbasutras. We also discussed some rope-based geometrical constructions. In this second part, let us compare how these toolkits fare against some historical geometrical construction problems. We also ponder the construction of the ‘tools’ themselves, for example, how might we establish whether a straight edge is indeed straight and so on

An elastic-plastic finite element model for rolling contact fatigue

Rolling contact fatigue (RCF) is a dominant source of failure in tribo-machinery. The two most important failure mechanisms in RCF are sub-surface originated spalling and surface originated pitting. In this study, both the fatigue damage mechanisms are investigated using a Voronoi finite element (VFEM) model in conjunction with a continuum damage mechanics approach. The combined methodology allows for evaluating the effects of material microstructure topology on fatigue life. First, by coupling an EHL line contact model with VFEM and effects of surface dents on fatigue life is evaluated. Next, the VFEM is extended to incorporate elastic-plastic material behavior in order to study the effects of material plasticity on RCF. Mises based plasticity model with kinematic hardening is employed to include the effects of material plasticity. The fatigue lives, spall patterns and fatigue life scatter obtained for surface and sub-surface initiated fatigue are found to be in good corroboration with experimental observations. Further, using the elastic-plastic finite element model, the effects of plasticity induced residual stresses on fatigue life is determined. Based on the numerical results, generalized equations are proposed in order to estimate the optimum preload required for achieving maximum enhancement in rolling contact fatigue life. Finally, the current model is combined with Fick\u27s law for stress assisted diffusion in order to capture carbon migration occurring during RCF. Using this approach, the microstructural alterations which are commonly observed in fatigued bearing microstructure are predicted which are found to be consistent with experimental findings