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The recent British Thoracic Society guidelines recommend that surgical mortality should not be greater than 8% for pneumonectomy and 4% for lobectomy. These cut offs are advanced as guidelines to [...]

The Benin continental margin was formed during the breakup of Gondwana through oblique rifting along transform faults. The evolution of topography following breakup directly affects the evolution of sedimentary basins, which has major implications for hydrocarbon exploration in the region. Quantitative constraints on erosion across Benin are limited to the Cenozoic, based on analysis of dissected lateritic palaeolandscapes. To resolve the Mesozoic erosion history, we have obtained apatite fission-track and single-grain (U-Th-Sm)/He data from 18 samples collected across a 600 km long transect through Benin. We invert these data, including available geological and geomorphological constraints, to obtain time-temperature paths, which are used to estimate magnitudes of denudation over the last 200 myr. Our study suggests that denudation was focused over a c. 300 km long seaward sloping limb of the marginal upwarp and at the southern margin of the interior Iullemmeden Basin from 140 to 100 Ma with lower magnitudes of denudation characterizing the continental interior and post-Cretaceous evolution of the margin. Models are consistent with modest burial (c. 1 km) of the Iullemmeden Basin between 120 and 85 Ma, and of the continental margin between 85 and 45 Ma. By the Eocene the first-order relief of Benin had developed, with regional erosion rates <20 m Ma-1 since then. [ABSTRACT FROM AUTHOR]

The reactions of n-butylbenzene, isobutylbenzene, sec-butylbenzene, and tert-butylbenzene on zeolite HBeta (SiO2/Al2O3 = 150) were studied at 350 °C using a pulse reactor with GC-MS analysis of product gases. Similar experiments also probed the reactions of butylbenzene isomers with excesses of methanol-¹³C. The reactions of tert-butylbenzene were also explored as a function of zeolite acid site density and reactant loading. In the absence of secondary reactions such as oligomerization and cracking, olefin product selectivity is governed by the detailed structure of alkyl side chains; for example, tert- and isobutylbenzene each yielded isobutene, but sec- and n-butylbenzene each gave equilibrium mixtures of 1-butene and cis- and trans-2-butene. The rate of butene elimination from the benzene rings increased with the degree of branching on the carbon α to the aromatic ring as well as the extent of in situ ring methylation by co-fed methanol. In the presence of methanol-¹³C, isomerization between 2-butene and isobutene did not occur through a direct pathway; rather skeletal isomerization was observed after chain growth to C7 or higher olefins followed by cracking. Coking reactions formed volatile alkanes through a mechanism that conserved the carbon skeleton of the precursor olefin. These studies relate to the hydrocarbon pool mechanism of methanol−olefin catalysis (MTO), as well as secondary reactions in MTO chemistry.

Background: In 1989, an outbreak of Q fever (C. burnetii infection) with 147 confirmed cases occurred in Solihull, West Midlands. Three patients developed cardiomyopathy in the subsequent 10 years. The cohort has been followed up with respect to the development of fatigue and, in this instance, cardiac effects after the original infection.
Aim: To determine whether persisting fatigue after Q fever represented sub-clinical cardiomyopathy.
Design: Prospective follow-up study.
Methods: All traceable subjects from the original outbreak, and community age-, sex- and smoking-matched controls, were studied. Questionnaires for idiopathic fatigue, 12-lead ECG, echocardiography, spirometry and shuttle walk distance were undertaken, and a subset with CDC-defined chronic fatigue syndrome had gated cardiac scans.
Results: Of the original cohort, 19 had died, three had emigrated and 10 were untraceable. Of the remaining 115, 108 responded to a mailed questionnaire and 87 were investigated further, of whom 85 provided complete data. Two developed aortic valve vegetations, one of whom died. Chronic fatigue syndrome was found in 20% of cases and 5.3% of controls (including those with co-morbidities), falling to 8.2% and 0 when excluding those with co-morbidities. There were no significant differences in ECG and echocardiographic investigations or shuttle-walk distance between those with fatigue and those without. Six of the seven patients with CFS had gated cardiac scans: all were within normal limits.
Conclusions: These findings do not support the existence of a sub-clinical cardiomyopathy in the patients in this cohort who suffer from fatigue after acute Q fever, although endocarditis can occur after acute infection.

The reactions of 1,2,4-trimethylbenzene, 1,2,4,5-tetramethylbenzene (durene), pentamethylbenzene, hexamethylbenzene (HMB), ethylbenzene, and cumene were studied on large-pore zeolite HBeta catalysts, either alone or with co-injection of methanol-¹³C. The reactivity of the methylbenzenes alone increased with increasing methyl substitution, as did selectivity for propene over ethylene. Disproportionation occurred for all methylbenzenes studied; in the case of HMB, pentamethylbenzene was a major volatile product, and we inferred that the heptamethylbenzenium cation also formed and remained in the catalyst. Substantially higher yields of olefins were obtained when methylbenzenes were co-reacted with methanol-¹³C. Ethylbenzene alone was unreactive at 350 °C, but when injected with five equivalents of methanol-¹³C, ethylbenzene formed ethylene-¹²C2 with very high selectivity. These and other experiments led to a detailed description of the hydrocarbon pool mechanism for MTO chemistry with side-chain methylation as the predominant route to olefins and the paring reaction as a possible minor pathway.

Summary Colonies of the queenless antPachycondyla krugeri were collected at different times of the year in order to determine the number of gamergates present. Dissection revealed that no colony contained more than one gamergate, suggesting that some form of regulation of gamergate numbers is present in this species. Groups of uninseminated workers kept in the laboratory began to lay reproductive eggs one month after removal from the influence of a gamergate, indicating that gamergates seem to regulate the reproductive activity of thir nestmates. Neither single reproductives nor reproductive regulation have previously been reported for species with gamergates.

Intracellular recordings were made from the P fibre, the smallest of the three afferent neurones innervating the thoracic-coxal muscle receptor organ of the crab (Carcinus maenas). While the two larger afferents are nonspiking, the response of the P fibre to a trapezoidal change in receptor muscle length consists of a single action potential signalling the onset of stretch superimposed on a graded amplitude receptor potential. The P fibre is sensitive to the velocity of the applied stretch, but is insensitive to static joint position, stretch amplitude and the velocity of the release phase. The presence and amplitude of the action potential depends on the initial length of the receptor muscle, the tension caused by efferent activation of the receptor muscle prior to receptor stretch, and on the velocity of stretch. Length constant (1.9 mm) and specific membrane resistance (76 KO · cm2) values obtained for the P fibre, together with its small diameter (7 µm) suggest that this neurone is less well adapted to conveying passive signals to the thoracic ganglion than are the S and T fibres. It is likely that the P fibre complements the length sensitivity of the S fibre and the tension and velocity sensitivity of the T fibre by signalling the onset of receptor stretch via single action potentials.

1. An interaction exists between two proprioceptive afferent neurons innervating the thoracic-coxal muscle receptor organ (TCMRO) of the crab, Carcinus maenas. Intracellular recordings were made from the extraganglionic regions of the afferents in order to characterize this interaction and its effects on sensory feedback. 2. A current-induced depolarization of the nonspiking T fiber of the TCMRO results in a depolarization of the P fiber, a small-diameter (7 microns) neuron innervating the same receptor. This interaction is graded in amplitude, and may result in a single action potential being superimposed on the graded response of the P fiber. A hyperpolarization of the T fiber has a smaller effect on the P fiber than a depolarization of similar amplitude. The interaction is rectified in a T- to P-fiber direction, and has a minimum central delay of approximately 3.6 ms. 3. The site of the interaction between the afferents is situated centrally, within the thoracic ganglion. Action potentials evoked in the P fiber by a T-fiber depolarization propagate actively and antidromically to the periphery. 4. Central modulation of the interaction occurs, because the amplitude of a T-fiber-induced depolarization is reduced in the P fiber during centrally generated spontaneous bursts of activity in the motoneurons of basal leg muscles. 5. Because of the interaction between T and P fibers, action potentials recorded from the peripheral portion of the P fiber during receptor stretch may be either orthodromic, resulting directly from the effects of the stretch on the sensory endings of the P fiber, or antidromic, resulting from the central input from the T fiber. 6. The T- to P-fiber interaction may serve to extend the dynamic sensitivity range of the P fiber, in particular by amplifying its sensory response at short receptor lengths and low velocities of stretch.

The case history is presented of a patient with acute respiratory failure complicated by nasal obstruction resulting in intolerance of nasal ventilation. Urgent insertion of nasal stents permitted restoration of ventilation with resolution of breathlessness and stabilisation of arterial blood gases.