The Congruence Extension Property and Related Topics in Semigroups.

A semigroup has the congruence extension property (CEP) provided that each congruence on each subsemigroup can be extended to a congruence on the semi-group. This property, the ideal extension property (IEP), and other related concepts are studied from both an algebraic and a topological perspective in this work. A characterization of semigroups with CEP is given in terms of the lattice of congruences. A similar result is obtained for IEP. Semigroups in which the relation is an ideal of is transitive (t-semigroups) are explored. It is shown that each of CEP and IEP implies this condition and that these are all equivalent for cyclic semigroups. Semigroups in which every subsemigroup is an ideal of some ideal (m-semigroups) are discussed. It is obtained that m-semigroups are periodic semigroups with zero and index less than or equal to 5. Those commutative m-semigroups with index less than or equal to 3 are characterized. The majority of these results are topologized for compact semigroups. Compact completely simple semigroups with CEP are characterized. A construction is given which yields an alternative proof for the known result in the algebraic case and is amenable to direct extension to the topological result. Additionally, subsemigroups of a completely simple semigroup with torsion subgroups are characterized. It is shown that CEP is retained by continuous homomorphic images of compact completely simple semigroups with CEP

Live longer and better without prosthesis-patient mismatch

In this issue of The Journal of Heart Valve Disease, Urso and co-workers (1) analyzed the impact of prosthesispatient mismatch (PPM) on survival and quality of life following aortic valve replacement (AVR) in 163 patients aged 75 years or more. Elderly patients currently represent a large proportion of the population undergoing AVR, and this proportion is expected to grow exponentially in the near future as the population ages. In this context, it becomes appropriate to determine the exact impact of PPM in this specific population in order to adopt the most appropriate strategies with regards to this age group. Indeed, these patients have often outlived their normal life expectancy, and their main motivation for consenting to surgery may be the expectation of an improved and/or maintained quality of life, rather than a prolonged survival. In this respect, the study by Urso et al. (1) is most interesting as these authors have analyzed the impact of PPM not only on the patients’ survival but also on their quality of life. Importantly, they found that, whereas moderate PPM had no impact on mid-term mortality in this cohort of elderly patients, it was nonetheless associated with a significant reduction in the quality of life

Illustration of the concentration and Flintshire furnace treatment of lead ores at the Desloge Mines, Missouri

The Desloge Mines, the subject of the present thesis, are situated in Township 37 North and Range 4 East, St. Francois Co. Mo. and are directly north of the St. Joe mines. They are 10 miles distant, in a north-easterly direction, from Cadet, a station on the St. Louis, Iron Mountain and Southern Rail-Road 57 miles from St. Louis. hough Cadet is insignificant in point of population, still as a shipping point, it ranks high among those in South East Missouri; since it is the depôt and entrepôt for the Desloge, St. Joe and Old Mines.... The subject of lead treatment at the Desloge Mines will be taken up in three separate parts viz: the Mining; Concentrating and Smelting of ores --pages 3-5

Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction: implications for diagnosis and treatment

Paradoxical low flow, low gradient, severe aortic stenosis (AS) despite preserved ejection fraction is a recently described clinical entity whereby patients with severe AS on the basis of aortic valve area have a lower than expected gradient in relation to generally accepted values. This mode of presentation of severe AS is relatively frequent (up to 35% of cases) and such patients have a cluster of findings, indicating that they are at a more advanced stage of their disease and have a poorer prognosis if treated medically rather than surgically. Yet, a majority of these patients do not undergo surgery likely due to the fact that the reduced gradient is conducive to an underestimation of the severity of the disease and/or of symptoms. The purpose of this article is to review and further analyse the distinguishing characteristics of this entity and to present its implications with regards to currently accepted guidelines for AS severity

Thin filaments elongate from their pointed ends during myofibril assembly in Drosophila indirect flight muscle

Tropomodulin (Tmod) is an actin pointed-end capping protein that regulates actin dynamics at thin filament pointed ends in striated muscle. Although pointed-end capping by Tmod controls thin filament lengths in assembled myofibrils, its role in length specification during de novo myofibril assembly is not established. We used the Drosophila Tmod homologue, sanpodo (spdo), to investigate Tmod's function during muscle development in the indirect flight muscle. SPDO was associated with the pointed ends of elongating thin filaments throughout myofibril assembly. Transient overexpression of SPDO during myofibril assembly irreversibly arrested elongation of preexisting thin filaments. However, the lengths of thin filaments assembled after SPDO levels had declined were normal. Flies with a preponderance of abnormally short thin filaments were unable to fly. We conclude that: (a) thin filaments elongate from their pointed ends during myofibril assembly; (b) pointed ends are dynamically capped at endogenous levels of SPDO so as to allow elongation; (c) a transient increase in SPDO levels during myofibril assembly converts SPDO from a dynamic to a permanent cap; and (d) developmental regulation of pointed-end capping during myofibril assembly is crucial for specification of final thin filament lengths, myofibril structure, and muscle function