The shape and tempo of language evolution

There are approximately 7000 languages spoken in the world today. This diversity reflects the legacy of thousands of years of cultural evolution. How far back we can trace this history depends largely on the rate at which the different components of language evolve. Rates of lexical evolution are widely thought to impose an upper limit of 6000–10 000 years on reliably identifying language relationships. In contrast, it has been argued that certain structural elements of language are much more stable. Just as biologists use highly conserved genes to uncover the deepest branches in the tree of life, highly stable linguistic features hold the promise of identifying deep relationships between the world''s languages. Here, we present the first global network of languages based on this typological information. We evaluate the relative evolutionary rates of both typological and lexical features in the Austronesian and Indo-European language families. The first indications are that typological features evolve at similar rates to basic vocabulary but their evolution is substantially less tree-like. Our results suggest that, while rates of vocabulary change are correlated between the two language families, the rates of evolution of typological features and structural subtypes show no consistent relationship across families.     

Remedial therapy after stroke: a randomised controlled trial.

Of 1094 patients with a confirmed stroke admitted to Northwick Park, a district general hospital, 364 (33%) died while in hospital, 215 (20%) were fully recovered when discharged, and 329 (30%) were too frail or too ill from diseases other than stroke to be considered for active rehabilitation. Only 121 (11%) were suitable for intensive treatment. They and 12 patients referred direct to outpatients were allocated at random to one of three different courses of rehabilitation. Intensive was compared with conventional rehabilitation and with a third regimen which included no routine rehabilitation, but under which patients were encouraged to continue with exercises taught while in hospital and were regularly seen at home by a health visitor. Progress at three months and 12 months was measured by an index of activities of daily living. Improvement was greatest in those receiving intensive treatment, intermediate in those receiving conventional treatment, and least in those receiving no routine treatment. Decreasing intensity of treatment was associated with a significant increase in the proportions of patients who deteriorated and in the extent to which they deteriorated. Probably only a few stroke patients, mostly men, are suitable for intensive outpatient rehabilitation, but for those patients the treatment is effective and realistic.     

The population increase of common guillemots Uria aalge on Skomer Island is explained by intrinsic demographic properties

The population of common guillemots Uria aalge on Skomer Island, Wales has been monitored since 1963, and in the last 30 yr has increased at an almost constant rate of 5% yr^?1. A previous attempt to model the population based on intrinsic demographic parameters estimated over just five years failed to explain the observed population increase, probably because the estimate of juvenile survival was too low. This raised the possibility that immigration fuelled the population increase. Here we use > 30 yr of detailed field observations to re‐estimate key population parameters (productivity, adult survival and juvenile survival) in order to model the population. We show that the observed rate of increase can be explained by these intrinsic parameters, and we therefore conclude that immigration is not necessary to generate the observed population growth.     

A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis

A biomechanical analog of curve progression and orthotic stabilization in idiopathic scoliosis has been developed using the classical theory of curved beam-columns. The interaction of the spinal musculature and other supporting structures is incorporated in the model using an equivalent flexural rigidity. The stability of a given scoliotic curve relative to a normal spine is described in terms of the so-called critical load ratio (Pc/Pe). This dimensionless quantity appears in the exact solution of the governing differential equation and boundary conditions. It is defined as the ratio of the load bearing capacity of a scoliotic spine (Pc) to that of a normal spine where the load bearing capacity of a normal spine is defined as Euler's buckling load (Pe). The computation of Pc/Pe is based upon a maximum allowable moment criterion. This model is used to study the effect of the degree of initial curvature and curve pattern in the frontal plane on the stability of untreated idiopathic scoliosis. Although restricted to two-dimensions, the model appears to demonstrate the synergistic effects of end support, transverse loading, and curve correction on improvement in relative stability of an orthotically supported scoliotic curve. The results of this study are in qualitative agreement with clinical findings that are based on long-term studies of natural history of idiopathic scoliosis and of patients undergoing orthotic management for scoliosis.     

Overview of drugs in arterial thrombosis

The recent history of randomized controlled trails in the prevention of ischaemic heart disease (i.h.d.) is considered. In 1970, it seemed that little could be done to prevent recurrent of the disease and there was almost no information on the potential for preventing its onset. Over the past decade, this rather pessimistic view has changed to one of guarded optimism. Yet there are still no drug régimes that command general support. One reason for the inconclusive results of recent trails may have been the assumption that myocardial infraction and sudden death share the same pathology. Another reason is the diversity of pathogenetic mechanisms and prognoses in i.h.d. Many patients probably stand little chance of benefiting from a particular drug either because it affects mechanisms other than those responsible for their disease or because their prognosis, excellent or hopeless, is unlikely to be influenced whatever treatment they receive. It is consequently difficult to ensure reasonable chances of demonstrating benefits in those who may really stand to gain. A tendency of pharmacological information to become available during or after a large trial, rather than beforehand, has added to the difficulties. Despite all their problems, randomized controlled trials remained the only way of testing drugs for the prevention of arterial disease. Suggestions are made for increasing the chances of clear results in future trails and of reaching the stage of benefit demonstrated sufficiently convincingly to form a basis for clinical practice. These suggestions include the use of factorial designs enabling the evaluation of more than one drug in a particular trial and the development of methods for selecting homogeneous groups of patients.     

Enzymes of carbohydrate metabolism in Leishmania donovani amastigotes

A method for the isolation of Leishmania donovani amastigotes from infected hamster spleen and liver tissues is described. Over 85% of the isolated amastigotes were viable as judged by acridine orange-ethidium bromide staining and in vitro transformation to the promastigote form. A comprehensive survey of the enzymes of carbohydrate metabolism in L. donovani amastigotes and promastigotes was conducted. Amastigotes and promastigotes possess all of the enzymes of the Embden-Meyerhof pathway, hexose monophosphate shunt, and tricarboxylic acid cycle. Cell-free extracts of both forms demonstrate an active glutamate dehydrogenase, thus linking activity which permits entry of pyruvate into the tricarboxylic acid cycle. Both forms demonstrate an active glutamate dehydrogenase, thus linking amino acid metabolism with carbohydrate metabolism. Pyruvate carboxylase, the enzyme responsible for replenishment of C4 acids by heterotrophic CO2 fixation into pyruvate, was also demonstrable in the tissue and insect forms. In general, activities of promastigote enzymes are higher than the amastigote enzymes. Differences between the vertebrate (amastigote) and invertebrate (promastigote) forms in their potential to utilize carbohydrates as substrates would appear to be quantitative rather than qualitative.