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PubMed1984

[Craniostenosis in Algeria. Surgical indications and results of a personal technic].

This paper is based on a predominant type of craniosynostosis seen in Maghreb, the oxycephaly (82,5% of all craniosynostosis in our series). The authors describe a surgical technic which is based on King's free flaps method, used by Acquaviva and Berrada, and Powiertowski's total craniectomy. With this technic, they perform craniectomy of the vertical part of the frontal bone, extended to temporal bone and 2-3 cm behind lambdoid suture. Two small flaps of parietal and temporal bones are left in place sparing temporal muscle insertion. The authors give results of 200 cases treated in the Neuro-Surgical Hospital Ali Ait-Idir Algiers, which consist in encephalic reexpansion and physiological redistribution of the cranial diameters. The authors emphasize a stabilisation is not a recovery from the functional signs, with normalisation in 3/4 of cases of the E.E.G. patterns. The visual acuity is stabilised. In conclusion, the authors estimate this technic has a place among the others procedures in the management of the craniosynostosis.

Algeria↗
PubMed1992

Relationship of tumor cell motility and morphologic patterns. Part 1. Melanocytic skin tumors.

In the diagnosis of melanocytic skin tumors, the assessment of the overall architectural pattern (silhouette) is often essential. We have previously shown by a computer simulation model that tumor patterns are likely to depend on the relative degrees of proliferation and motility of the tumor cells. In this study, we examined the morphological pattern of 12 cases each of nevocellular nevi, primary melanoma, and metastatic melanoma by image analysis. The patterns of the individual melanocytic skin tumors were compared statistically with patterns generated by computer simulation, which facilitates estimates of biological properties of the tumor cells. Additionally, mitotic counts were made to measure tumor cell proliferation. A comparison of the three diagnostic groups revealed that the cells of nevocellular nevi show a low degree of motility, which, however, still exceeds the very low degree of proliferation. Thus, an "invasive" pattern with numerous small nests and single cells at the base of the lesion is common. In primary malignant melanoma, tumor cell motility and tumor cell proliferation are significantly increased in various proportions, thus leading to varying morphological patterns. In metastatic melanoma, a strikingly elevated degree of proliferation exceeds the only slightly elevated degree of motility and leads to sharply demarcated, "expansive" lesions. To check the validity of the technical procedure, estimates of proliferation based on pattern analysis alone were compared with the results obtained by mitotic counts. There was a significant correlation, indicating that the assumptions of the computer model and the image analysis procedure are in fact applicable to real-life melanocytic skin tumors.(ABSTRACT TRUNCATED AT 250 WORDS)

Cell Division↗
PubMed1993

[Population forecast for Hungary, 1993-2020].

"The author discusses the results of [an] age-specific technical population forecast up to 2020, based on the latest available population and vital statistics [for Hungary]. The forecast starts from population figures as at 1 January 1993, that have been statistically updated from the 1990 census data, and it assumes that indicators of demographic trends (fertility, mortality) of 1992 will remain unchanged in the period between 1993 and 2020." (SUMMARY IN ENG AND RUS)

Age Factors↗
PubMed1990

[Significance of digital subtraction angiography for estimation of early results of myocardial revascularization after internal mammary artery grafting].

Between 1st January and 31st December 1987 126 consecutive patients underwent full myocardial revascularization using at least one internal mammary artery bypass grafting in Department of Cardiovascular Surgery of University of Freiburg. In 78 patients (75 males, 3 females) DSA was performed within 8 days after surgery to evaluate dynamics of IMA-graft. The age ranged from 38 to 67 years (mean 53.4 years). DSA study was performed through the brachial artery, contrast medium was injected with flow of 10 ml/sec. in counter current. It was only one series of angiograms necessary to visualise flow from subclavian artery, through IMA to coronary artery. Among 78 investigated patients in 61 (78%) the distal anastomosis appeared to be widely patent and flow through the IMA and anastomosed coronary artery was sufficient. Patency of one of the branches of IMA or stenosis of IMA graft contributed to inadequate flow in 12 patients (15.6%). In 5 (6.4%) operated patients the IMA graft was not patent. Counter current intraarterial DSA requires much smaller amount of contrast medium than classical angiography, moreover avoiding of aortic catheterization with all risks involved. The counter current intraatrial DSA is an excellent technics of estimation of the flow to grafted coronary arteries. The method is easy to perform, repetitive and carry very small risk for the patient. Early postoperative evaluation of IMA-graft patency is essential for estimation of effectiveness of myocardial revascularisation and prognosis for the patient.

Adult↗
PubMed1998

K-12 enrollment forecasting: merging methods and judgment.

"This article describes an enrollment forecasting process in which technical experts and local community stakeholders [in Oregon] worked together to produce data that were cost-efficient and yet accurate enough to serve as the basis for sound decisions. The large school district that employed this process gained valuable insights to guide its attendance zone and facilities planning decisions, and also created a group of key communicators to ensure community understanding and support."

Americas↗
PubMed1988

Development and validation of an automated method of the Selvester QRS scoring system for myocardial infarct size.

The Selvester QRS score for estimation of myocardial infarct (MI) size from the standard 12-lead electrocardiogram (ECG) has not yet achieved wide recognition as a valuable tool in the routine assessment of the MI patient, primarily because of the practical limitations inherent to manual application. This study examined the ECGs of 438 patients (105 normal subjects, 161 with "possible" MI and 172 with "definite" MI based on data from cardiac catheterization) to develop software for an automated method of the Selvester system in attempts to overcome the manual constraints. After a comprehensive validation process involving extensive interactions between the manual scorer and the software developer, an automated method of the Selvester system was generated that had a high correlation with manual application (r = 0.94) and was superior regarding time, training, reader bias, reproducibility and precision of measurement. These results indicate that an automated version of the Selvester QRS scoring system would resolve many of the limitations of manual application and would provide a reliable, technically accurate estimate of MI size that could be incorporated into ECG diagnostic programs and used in standard digital ECG machines.

Cardiac Catheterization↗
PubMed1997

Methods for estimating missing data on migrants in the 1991 British census.

"This paper discusses the use of suppression to protect data in the Special Migration Statistics, a dataset produced from the 1991 [British] Census, and argues that this procedure prevents accurate analysis of the data. A computer program is described that uses a series of methods to ¿recover' data which were suppressed, and to estimate those parts of the data which cannot be recovered.... The program has been used to recover and estimate data successfully, and results include sample tables of migrants between types of districts by ethnicity."

Censuses↗
PubMedDate not supplied

Estimating ethnic change in London, 1981-91, using a variety of census data.

"This paper provides estimates of ethnic minority populations in 1981 in Greater London so that spatial population change can be measured. The estimation method involves the application of conditional probabilities of ethnicity given the country of birth. Several different data sources from the census of population have been used to compute the conditional probabilities. Each of these sources has deficiencies; the new method proposed here employs data on 1981-91 survivors in the ONS Longitudinal Study (LS). The estimated ethnic minority populations for 1981 are smaller than those generated using 1991 Census data, and hence the estimate of change is larger. Careful pairwise comparisons are made between alternative estimates. A set of very different maps of change, based on the LS method, are presented and interpreted for the ethnic groups of London at the borough scale."

Culture↗
PubMed1993

Reproductive health, population growth, economic development and environmental change.

World population will increase by 1000 million, or by 20%, within 10 years. Ninety-five per cent of this increase will occur in the South, in areas that are already economically, environmentally and politically fragile. Morbidity and mortality associated with reproduction will be greater in the current decade than in any period in human history. Annually, 40-60 million pregnancies will be terminated and 5-10 million children will die within one year of birth. AIDS-related infections, e.g. tuberculosis, will undermine health care in Africa (and elsewhere) and in places AIDS-related deaths will decimate the work-force. The growth in population and associated morbidity will inhibit global economic development and spawn new problems. The key issues are migration, the spread of disease, the supply of water and the degradation of land, and fiscal policies with respect to family planning, pharmaceuticals and Third-World debt. Full education, particularly of women, and more effective family planning in the South have the power to unlock the problem. Failure will see the developed countries, with their 800 million population, swamped by the health, economic and environmental problems of the South, with its projected population of 5400 million people for the year 2000.

Demography↗
PubMed1986

Differential mortality in Turkana agriculturalists and pastoralists.

Nomadic pastoral populations appear to have much lower rates of growth than the otherwise very high growth rates now characteristic of populations in developing nations. Because dramatic declines in infant mortality have been a primary contributor to increased population growth rates in these countries, it has been assumed that nomadic pastoral populations are still characterized by high levels of mortality in the first few years of life. Few studies, however, have been undertaken to estimate demographic parameters for nomadic pastoral populations, and even fewer of a comparative nature have been undertaken to document the impact of subsistence strategy on demographic processes. This study compares indirect childhood mortality estimates for Turkana nomadic pastoralists with childhood mortality in a settled agricultural group within the same population and finds that pastoralists have substantially higher levels of mortality. Based on the childhood mortality estimates, model life tables are selected for pastoral and agricultural groups from which values for mean life expectancy and infant mortality are estimated and compared. Recent improvements in primary health care for the settled agricultural group are ruled out as being an important cause of their lower mortality levels, and some aspects of life-style associated with subsistence strategy are discussed as likely determinants of the mortality differences.

Adolescent↗
PubMed1990

Modeling the prehistoric Maori population.

Skeletal and comparative evidence of mortality is combined with fertility estimates for the precontact Maori population of New Zealand to determine the implied rate of precontact population growth. This rate is found to be too low to populate New Zealand within the time constraints of its prehistoric sequence, the probable founding population size, and the probable population size at contact. Rates of growth necessary to populate New Zealand within the accepted time span are calculated. The differences between this minimum necessary rate and the skeletally derived rate are too large to result solely from inadequacies in the primary data. Four alternative explanations of this conundrum are proposed: 1) skeletal evidence of precontact mortality is highly inaccurate; 2) skeletal evidence of fertility is severely underestimating actual levels; 3) there was very rapid population growth in the earliest part of the sequence up to 1150 A.D., from which no skeletal evidence currently is available; or 4) the prehistoric sequence of New Zealand may have been longer than the generally accepted 1,000-1,200 years. These alternatives are examined, and a combination of the last two is found to be the most probable. The implications of this model for New Zealand prehistory and Oceanic paleodemography are discussed.

Fertility↗
PubMed1994

Neonatal size and infant mortality at high altitude in the western Himalaya.

A prospective study was undertaken in Ladakh, India, a high-altitude region of the Himalaya, to investigate the effects of small average birth size on neonatal mortality. While such studies exist from high-altitude regions of the New World and shed light on the adaptive status of high-altitude-dwelling populations there, this is the first to examine this relationship in the Himalaya. In a sample of 168 newborns, birthweight and other anthropometric measurements were reduced relative to Andean and Tibetan newborns. Logistic regression and hazard analysis showed that neonatal biological characteristics such as weight, fatness, and circumferences were important predictors of survival probabilities of infants, especially in the neonatal period. Low Rohrer's Ponderal Index (PI) was particularly strongly related to poor survival outcome. Males and females showed no significant differences in mortality risk. Data derived from reproductive histories revealed that neonatal mortality accounted for 70-80% of total infant mortality in Ladakh. Compared to other high-altitude studies, small newborn size in Ladakh was associated with much higher mortality risks; mortality risk rose dramatically with birthweights below the mean (2,764 grams), which characterized 50% of all newborns. It is argued that newborns in Ladakh are subject to strong directional selective forces that favor higher birthweights that incur lower risks of neonatal mortality, while Andean infants are subject to relatively mild selection pressure at both ends of the birthweight distribution. Given the overall small size at birth of Ladakhi newborns and the poor survival outcomes of newborns below the mean, it is suggested that this population is less well adapted in a biological sense to the stresses inherent in this high-altitude environment than are Andean populations, perhaps due to the relatively recent colonization of the area and the substantial genetic admixture that has occurred in the past.

Altitude↗
PubMed1984

Mortality of a heterogeneous cohort; description and implications.

"A recent model for heterogeneous mortality by Vaupel et al....is shown to be based on incorrect definitions. An alternative formulation is presented. The results indicate that current methods for computing the survivorship and life expectation functions underestimate the true values. A method is given for determining the possible magnitude of this underestimation. The method is illustrated by a numerical example using U.S. data."

Americas↗
PubMed1989

A probabilistic approach to the construction of competing-risk life tables.

"This paper aims to identify net and partial-crude probabilities in the competing-risk life table context, by using probabilistic approaches. Five types of lifelength random variables are defined to formulate these nonidentifiable probabilities. General expressions for net and partial-crude probabilities are first derived under independent risks assumptions. Two sets of explicit formulas for estimating the net and partial-crude probabilities are then derived in terms of the identifiable overall and crude probabilities by making the additional assumption of piecewise uniform distribution of the lifelength random variables. A study of the degree to which nonidentifiability can affect the net and partial-crude probabilities in a variety of situations is developed. An example from cross-sectional studies is employed to illustrate the methodology developed."

Biology↗
PubMed1984

Simulation modeling perspectives of the Bangladesh family planning and female education system.

A systems dynamics simulation study of the interaction of various social subsystems in the People's Republic of Bangladesh is chosen to address integrated planning concerns. It is concluded that one should not underestimate the potential of noneconomic societal forces: They can have a positive impact on slowing population growth and improving the quality of life. Methodologies included: fuzzy profiles for choosing primary variables; interpretive impact matrices to generate the systems dynamics equations; interactive computer capabilities for purposes other than simulation runs; modeling log file to note modeling assumptions, changes, and redefinitions; and microcomputer portability.

Adolescent↗
PubMedDate not supplied

How accurate are the U.S. Bureau of the Census projections of total live births.

"The accuracy of total live birth forecasts issued by the U.S. Bureau of the Census was analysed. Forecast accuracy has not improved significantly since 1950. Further, the forecasts are not more accurate than several naive alternatives. Moving from a period methodology to a cohort methodology improved forecast accuracy for certain forecasts. [It is demonstrated that] the Bureau of the Census systematically underestimated total births in the upswing and overestimated in the downswing."

Americas↗
PubMedDate not supplied

Household projection methods.

"The role of household projections as a basis for forecasts of households at [the] national and sub-national level is discussed and a number of criteria for such projections are outlined. The projection method used by the Department of the Environment [in the United Kingdom] is examined in the context of these criteria and it is concluded that it is both practical and robust. However, it is open to criticism, first because of its failure to make the best use of the available data and of theoretical knowledge, and secondly because of its 'black box' nature. An alternative two-stage strategy is developed. The first stage involves constructing projections using a new curve-fitting method which takes account of within cohort life-cycle headship rate changes. The second is a method of analysing the resulting projections by modelling transition rates between different household states. Worked examples of both methods are presented."

Developed Countries↗
PubMedDate not supplied

Forecasting with growth curves: the effect of error structure.

"The main theme of this paper is an investigation into the importance of error structure as a determinant of the forecasting accuracy of the logistic model. The relationship between the variance of the disturbance term and forecasting accuracy is examined empirically. A general local logistic model is developed as a vehicle to be used in this investigation. Some brief comments are made on the assumptions about error structure, implicit or explicit, in the literature." The results suggest that "the variance of the disturbance term, when using the logistic to forecast human populations, is proportional to at least the square of population size."

Forecasting↗