Rates In Different Groups Research Articles

Safety and efficacy of eprosartan, a new angiotensin II receptor blocker

Angiotensin-converting enzyme inhibitors have been used extensively in the management of hypertension and related cardiovascular conditions. However, this treatment approach is limited by lack of specificity and continued production of angiotensin II by other routes. Antagonism of the angiotensin II receptor offers the possibility of improved control of hypertension by providing a more complete blockade of the renin-angiotensin system than angiotensin-converting enzyme inhibition without bradykinin-related effects. Eprosartan is the only nonbiphenyl, nontetrazole competitive angiotensin II receptor antagonist clinically available and is highly selective for the AT1 receptor subtype. In clinical trials, eprosartan has been shown to lower blood pressure effectively in a once-daily regimen in hypertensive patients. In the recommended dose range of 600 to 1200 mg once daily, eprosartan is effective in patients with all grades of hypertension irrespective of age, sex, or race. Furthermore, the tolerability profile of eprosartan is comparable to that of placebo, and there are no known clinically relevant drug-drug interactions. A number of large-scale clinical studies are currently underway or planned to determine which of the increasing number of AT1 receptor antagonists may reduce cardiovascular morbidity and mortality rates in different groups of hypertensive patients. Meanwhile, current evidence suggests that the AT1 receptor antagonists represent a significant new approach to cardiovascular therapy and merit a fuller assessment in hypertension and other cardiovascular diseases. (Am Heart J 1999;S238-S245.)

Recurrent Hereditary Polyserositis or Familial Mediterranean Fever: An Overview

The etiology and pathogenesis of recurrent hereditary polyserositis (RHP) remain undetermined. There is a good evidence for a genetic basis (transmission being by a recessive Mendelian mode of inheritance), but not all cases have a family history and an infective (or other environmental) components has not been excluded. The marked variation in presentation and complications (in particular the prevalence of amyloid deposition) in different series suggests that this might not be a homogeneous entity. Vascular involvement is a basic prerequisite for the periodic attacks, and evidence for transient immunological abnormalities is incontrovertible. There are no reliable diagnostic techniques. Colchicine is of value in treatment, but its mode of action is unclear. More macro- and microepidemiological studies are required and will be of paramount importance. Clinical observations and molecular genetic studies should address the possibility that two or more immunological or metabolic defects might be interwoven; why for example do only some affected groups develop AA amyloidosis? Simple, non-invasive diagnostic tests are required for the uncomplicated disease and also for the presence of amyloid deposition. Preventive strategies might eventually involve genetic engineering techniques, but in the immediate future, education of doctors and other health care workers - to raise the "index of awareness" of RHP, in order that colchicine treatment can be commenced early in the disease - forms an important strategy. Colchicine therapy is not without complications and an alternative chemotherapeutic agent should be sought.

Aggregate Unemployment in Italy, 1960-1983

When compared with other countries' experiences, the Italian performance on the unemployment front is interesting in many respects. As indicated in Table 1, the Italian unemployment rate has been consistently above that of major Western countries since the 1960s. The differential in unemployment rates tended to decrease between the second half of the 1960s and the first half of the 1970s because the initial rise in unemployment following the oil shock was less pronounced in Italy than in most other countries. Since that time the rise in unemployment has been pretty universal and steady, but Italian unemployment has risen somewhat faster than the average; thus the differential with the OECD has grown from 1 percentage point to over 2 by the early 1980s, though the EEC as a whole has performed even worse. In assessing these trends, one should keep in mind that unemployment, as well as many other Italian statistics, is subject to an unusual margin of error, reflecting in part the large role played by the 'underground' economy. Furthermore, as for other countries, the aggregate Italian unemployment rate hides substantial differences in unemployment rates for different groups of people in society (see Section I below). Though extremely important, such

The shape of evolution: systematic tree topology

Three hypotheses that predict probabilities associated with various tree shapes, or topologies, are compared with observed topology frequencies for a large number of 4, 5, 6 and 7-member trees. The united data on these n-member trees demonstrate that both the equiprobable and proportional-to-distinguishable-types hypotheses poorly predict tree topologies, while all observed topology frequencies are similar to predictions of a simple Markovian dichotomous branching hypothesis. Differences in topology frequencies between phenetic and non-phenetic trees are observed, but their statistical significance is uncertain. Relative frequencies of highly asymmetrical topologies are larger, and those of symmetrical topologies are smaller, in phenetic than in non-phenetic trees. The fact that a simple Markovian branching process, which assumes that each species has an equal probability of speciating in each time period, can predict tree topologies offers promise. Refinement of Markovian branching hypotheses to include the possibility of multiple furcations, differential speciation and extinction rates for different groups of organisms as well as for a single group through geological time, hybrid speciation, introgression, and lineage fusion will be necessary to produce realistic models of lineage diversification.

Some Notes on Comparing Changes in Educational Enrollment and Transition Rates

Abstract Noonan, R. & Elgqvist‐Saltzman, I. 1982. Some Notes on Comparing Changes in Educational Enrollment and Transition Rates. Scandinavian Journal of Educational Research 26, 141‐160. Comparing enrollment and transition rates for different groups is simple. However, to compare changes in these rates is problematic, because the basis for the comparison is typically different for the different groups. Sometimes logit or other transformations'are used to give a single index for each group, and these indices are then compared. Such transformations have undesirable mathematical properties and lack clear theoretical interpretations. In order to understand the dynamics of development trends, it is necessary to examine not only the enrollment or transition rates but also the absolute numbers that constitute the bases for these rates. The problem is illustrated using some current Swedish data on enrollment and transition rates in higher education for men and women.

Phyletic diversity in higher plants

The term “phyletic diversity” is used here to denote the continued co-existence and evolution of separate major phyletic groups which have a similar mode of life (e.g. within the angiosperms). This work attempts to show that an understanding of the factors which determine the degree of phyletic diversity could contribute to understanding the nature and evolution of higher taxonomic categories, such as families. The opposite of phyletic diversity, phyletic uniformity (Fig. 1A—B), should result from unequal evolutionary rates of different groups and repeated adaptive radiations of the most successful groups; the following competition for essential, limiting resources should lead to the extinction of all less rapidly evolving, inferior groups. At least some plant families are shown to have specific adaptive specializations which give them competitive advantages for part of the environmental resources only. This ensures their co-existence and the maintainance of phyletic diversity. The nature of these family specializations is considered briefly. It is shown that physiological adaptations to particular conditions, symbioses which aid in obtaining nutrients and, especially, chemical defence mechanisms could be major components of these specializations and thereby the raison d'etre of plant families.

Four and a half years experience with a vertical flow sterile enclosure

During the use of a vertical flow enclosure of our own design for almost five years, bacteriological studies and the infection rates in different groups of patients have taught us the following: 1. In a clean room operating theatre, the use of a respired air exhaust system improves the sterility compared with the use of ordinary masks. In a vertical flow enclosure, the chest, the arms, and the hands of the team are contaminated from respired airborne bacteria if helmets, etc., are not worn. 2. In our vertical flow enclosure with almost continuous absolute sterility of the air, the infection rate in primary total hip replacement is very low and less than 1%, including early and late infections. Antibiotics have not been used. In secondary surgery, i.e., total hip replacement in hip joints previously operated upon, the infection rate is markedly higher, probably because of a flare-up of latent infection. “Clean room” surgery therefore, can only prevent air borne contamination, and no more; but this is very valuable. 3. Vertical flow enclosures of the Charnley-Howorth (1975) and Weber et al. (1971) type provide considerable improvement in sterility of the air compared with adaptations of more conventional theatres. We recommend that these facilities be made available for implant surgery. It is also necessary to have a stringent operational policy with cooperation and discipline on the part of all members of the theatre team.

The preparation and assessment of a suitableMucor pusillusLindt proteinase–swine pepsin mixture for Cheddar cheese-making

SummaryA simple test procedure was used to predict the most suitable mixture of Noury rennet (Mucor pusillusLindt proteinase) and swine pepsin for Cheddar cheesemaking. Duplicate cheeses were made with 6 Noury rennet–swine pepsin mixtures and with each enzyme alone, with calf rennet as the control. There were slight differences in the course of the cheese-making process and in the yields of the cheeses. Sensory evaluation showed that the most acceptable cheeses were those made by coagulant mixtures closely similar to the predicted mixture and these were as acceptable as cheeses made with calf rennet. The survival rates of different groups of bacteria were similar in all cheeses. There were differences in the products of proteolysis in the various cheeses throughout ripening, particularly with respect to products derived from αs1-casein. The Noury rennet was characterized for the proportion of milk clotting activity associated with each of 4 components and its stability in solution was determined.

Differential fertility among immigrants to England and Wales and some implications for population projections.

SummaryThe age structure of the immigrant female population as shown by the 1961 Census was heavily biased towards the young adult age groups, where fertility rates are highest. The birth rate for such a population could be expected considerably to exceed the average for this country as a whole, due to differences in age structure alone. The Census also showed marked differences betwen the fertility rates of different groups of immigrants but suggested that for the most important groups —from the Irish Republic, the Indian sub-continent and the Caribbean—they then amounted to a completed family size of roughly ½ child above the England and Wales average. There were also marked differences in 1961 between the socio-economic structure of immigrant groups; such evidence as there is points to socio-economic factors as playing an important part in explaining the fertility of immigrants, and its possible change over time.

Loss of Cathexes as a Common Psychodynamic Characteristic of Cancer Patients: An Attempt at Statistical Validation of a Clinical Hypothesis

It is hypothesized that the cancer patient has, more often than chance alone would permit, lost a major cathexis some time before the development of the neoplasm. Certain predictions as to relative cancer mortality rates in different groups are made from this hypothesis. An examination of the statistical literature in the cancer field bears out these predictions and offers additional evidence. The possible validity of this hypothesis suggests that further investigation would be highly desirable.

Factors Contributing to the Multiple Decrement of Piano Tone Envelope

The decrease in decrement of piano tone envelope with tone duration has been reported previously. Possible causes of the rate change have now been investigated, including the following: different rates for different groups of vibration modes; nonlinearity of transformation of mechanical energy to acoustical energy; storage of mechanical energy for subsequent acoustical radiation; transfer of energy between string modes perpendicular and parallel to the bridge; interference between strings which are almost exactly in tune; and change in rate of energy transfer from the multiple-string source, before and after transition from an initial in-phase condition to a later out-of-phase condition. The suggestion of the last factor and its theoretical basis was the specific contribution of Dr. Benioff. The last two factors, which are closely related, were found to control the rate change in most cases.

LOSS OF CATHEXES AS A COMMON PSYCHODYNAMIC CHARACTERISTIC OF CANCER PATIENTS: AN ATTEMPT AT STATISTICAL VALIDATION OF A CLINICAL HYPOTHESIS

It is hypothesized that the cancer patient has, more often than chance alone would permit, lost a major cathexis some time before the development of the neoplasm. Certain predictions as to relative cancer mortality rates in different groups are made from this hypothesis. An examination of the statistical literature in the cancer field bears out these predictions and offers additional evidence. The possible validity of this hypothesis suggests that further investigation would be highly desirable.

SUGGESTIONS AS TO QUANTITATIVE MEASUREMENT OF RATES OF EVOLUTION

The best known recent work on rates of evolution is probably that of Simpson (1944), though Small's (1945, 1946) work on diatoms is more extensive. Small is concerned with the origin of species, which in this group seems to be a sudden or almost sudden process. Simpson compares evolutionary rates in different groups mainly by means of data on the origin and extinction of genera. Now among living animals and plants the distinction between genera is much less objective than that between species. On the other hand the paleontologist often finds it hard to be sure of differences less than generic. Moreover the criteria of generic distinction are certainly different in different groups. For example good systematists from Linnaeus onward have assigned the polecat (Mustela putorius) and the ferret (Martes furo) to different genera, while in fact they give quite fertile hybrids and are probably to be regarded as at most subspecifically different. On the other hand I know of no viable, let alone fertile, hybrids between animals assigned to different genera of Diptera or Amphibia. This sugests that animals are rather more readily placed in different genera among mammals than in some other classes. And in view of the incomplete character of the best fossil remains, the systematics of extinct animals are certainly less uniform than that of living ones. On the other hand the dimensions of a solid organ, such as a tooth, a shell, or a bone, are often measureable with great precision; and when we have a series of fossil populations, believed to form a lineage, we can calculate the rate of change of the mean value of any measure. In speci-C-ne o _ t lxr ..a l *.. r+ I:rnilc for% +111 time and for the character. From data on radioactivity we have a fairly precise measure of the duration of the whole tertiary period, and less accurate dates within it; and estimates of ten million years during this period are not likely to be out by much more than 25%o. The precisely dated strata from earlier rocks are not so common. The error is likely to be a good deal greater in paleozoic or mesozoic marine deposits where we have continuous records over some millions of years, as in the English chalk or Lias. Here estimates of time may very well be out by a factor of 2, but are hardly likely to be so by a factor of 10. As biologists we should like to be able to measure time in generations. In a fair number of insects the generation is exactly a year, in others there are two generations per year, and so on. Where generations overlap, as in most vertebrates, we can theoretically define a mean generation length exactly by definite integrals if we have life and fertility tables. In fact we can never do so for fossil forms. But we can be fairly sure that for a small rodent the mean generation length was less than a year, for most ungulates more so. For mammals not larger than a cow we may be fairly sure that it was under ten years. The longest mean initerval between sexual generations is probably to be found in clonally propagated invertebrates such as corals, where it may possibly extend over centuries. If evolutionary rates depend on mutation rates (which is doubtful), the year is as natural a unit as the generation. For it seems possible that the intensity of natural radiation produces a minimum mutation rate per unit of time which is often exceeded (as in Drosophila) but below