Dyskeratosis Congenita: Squamous Cell Carcinoma of the Buccal Mucosa on a Background of Lichen Planus – A Case Report During COVID-19 Pandemic

Dyskeratosis Congenita is a severe disorder that involves several systems in the human body and is well-known for its transmission hereditarily through generations. The triad of a) reticular atrophy of the skin with pigmentation b) dystrophy of the nails c) leukoplakia of the oral mucosa characterises this uncommon disorder, which most commonly affects men. One of the key reasons for premature death in this disease is malignant transformation within areas of mucosal hyperkeratosis. In Dyskeratosis Congenita, the simultaneous existence of squamous cell carcinoma (SCC) with lichen planus and or lichenoid reactions in the mucosa of the oral cavity is a rare, stated condition. This report discusses a case of a Libyan male patient affected by Dyskeratosis Congenita that ended with buccal mucosal squamous cell carcinoma developed on a lichen planus background after thirty years of suffering at the age of 64.

Reliability Analysis of Overhauled Engines of Dumpers

Mining industry in India currently occupies a coveted position in the world league table. Large scale mechanization has made major breakthroughs in this industry. Mechanization trends have introduced sophisticated off-road dumpers as the main ore/rock transporting equipment in opencast mines. To achieve targeted production and to survive intense competition in the mining industry, it is imperative that the dumper as an equipment and its different operating units should be reliable and maintained effectively to ensure its maximum availability. The diesel engine is the most critical operating unit of a dumper. To improve the performance and to reduce frequency of downtime, the engines need overhauling time to time. The engine after overhauling should be able to perform its desired function under stated condition for a specified period of time. The present study investigates reliability of overhauled engines in a fleet of dumpers used in an opencast mine. In this paper the operational reliability of overhauled engines, mean time to overhaul (MTO) and time between inspection (TBI) are examined. MTO and TBI values predicts the next time to overhaul and inspection respectively, which will aid in reducing the downtime of dumpers and thereby increasing their availability.

Finding Carmichael numbers

Recall that Fermat's ‘little theorem’ says that if p is prime and a is not a multiple of p, then ap − 1 ≡ 1 mod p.This theorem gives a possible way to detect primes, or more exactly, non-primes: if for some positive a ≤ n − 1, an − 1 is not congruent to 1 mod n, then, by the theorem, n is not prime. A lot of composite numbers can indeed be detected by this test, but there are some that evade it. In other words, there are numbers n that are composite but still satisfy an − 1 ≡ 1 mod n for all a coprime to n. Such numbers might be called ‘false primes’, but in fact they are called Carmichael numbers in honour of R. D. Carmichael, who demonstrated their existence in 1912 [1] – so the year 2012 marks their centenary. (Composite numbers that satisfy the stated condition for one particular a are called a-pseudoprimes. They are the subject of a companion article [2].)

The Boundary Conditions Governing Fluid Motions in Porous Media

Further work has shown that the second of conditions (2.4) of a recent paper (Philip 1957?), supposed to govern the potential distribution during fluid motion in a porous medium, holds only for the case of linear axial flow in tubes of general cross section. The stated condition implied that the equipotential surfaces intersected the fluid-solid interface (a stream surface) normally. This may be approximately true for all media, but it can be shown by reference to the "complete" Stokes-Navier equation ((1.9) of Philip 1957) to be not exact in general. It follows that equation (2.8) and the thermal analogy (Section III) presented in that paper hold exactly for axial flow in tubes of general cross section, but are merely approximations when applied to more general media. Exact analysis for the general medium promises to be complicated and will not be pursued here.