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At least 73 records · Page 4Linked to original sources

Life expectancy as a summary of mortality in a population: statistical considerations and suitability for use by health authorities.

OBJECTIVE: To investigate the sampling distribution and usefulness of expectation of life in comparisons of mortality at health district level or below. DESIGN: Derivation of a formula for the variance of the expectation of life, confirmation of the result and generation of the sampling distribution by Monte Carlo simulation; comparison of expectation of life with standardised mortality ratio (SMR) and other summary indices of mortality. SETTING: A health district in Trent Region, England. SUBJECTS: Routinely available mortality statistics at electoral ward level and above. MAIN RESULTS: Given reasonable and simple assumptions the sampling distribution of the expectation of life is approximately normal. Expectation of life shows a high negative correlation with SMR even if the oldest age band for the SMR is open ended. CONCLUSIONS: Where sampling error is an issue, inference concerning differences in mortality rates between populations can be based on expectation of life, which is better for illustrative purposes than SMR. The formula for the variance of the expectation of life is more complex however. If the final age band is open ended, its lower bound should be as high as possible to avoid misleading results caused by hidden differences in age structure.

Age Factors↗

[Population statistics of Triatoma sordida Stäl 1859 (Hemiptera:Reduviidae) in experimental conditions].

Four cohorts of 100 Triatoma sordida eggs were reared under standard laboratory conditions (28 degrees C, 63% R.H.) and fed weekly on hens during 40 minutes. The numbers of dead insects, moults and eggs laid were recorded weekly. A constant survival value was observed without any important peaks in the four cohorts. Life expectancy was 37.4 weeks for males and 36.8 weeks for females. The average generation time was 61.7 weeks. The average net reproduction rate suggests that this population would increase 143.2 times during each generation. The average intrinsic rate of natural increase was 0.082 per individual per week. The highest reproductive value was observed 3 weeks after entering the adult stage. The age structure, assuming stable age distribution, would be 32% eggs, 26% of first instar nymphs, 19% of second instar nymphs, 13% of third instar nymphs, 6% of fourth instar nymphs, 3% of fifth instar nymphs and 1% of adults. Our results suggest that this species behaves as a k-strategist under experimental conditions.

Animals↗

A stochastic model for PSA levels: behavior of solutions and population statistics.

This paper investigates the partial differential equation for the evolving distribution of prostate-specific antigen (PSA) levels following radiotherapy. We also present results on the behavior of moments for the evolving distribution of PSA levels and estimate the probability of long-term treatment success and failure related to values of treatment and disease parameters. Results apply to a much wider range of parameter values than was considered in earlier studies, including parameter combinations that are patient specific.

Adenocarcinoma↗

A model for prelingual deafness, the congenitally deaf white cat--population statistics and degenerative changes.

Cochlear implantation in congenitally deaf children leads to electrical stimulation of an entirely naive central auditory system. In this case, processes of central auditory maturation are induced by the electric stimuli. For the study of these processes the deaf white cat (DWC) appears to be an appropriate model. However, a knowledge of the basic data of these animals is necessary before such a model may be used. This paper presents these data and is one of a series of publications concerning congenital deafness in children and cochlear implantation. In our strain 72% of the animals are totally deaf as judged by the absence of any brain stem evoked potentials at click intensities up to 120 dB SPL peak equivalent. Primarily, there is a degeneration of the entire organ of Corti during the first postnatal weeks. An absence of acoustically evoked brain stem responses in the early postnatal weeks shows that DWCs probably never have any hearing experience. Months after the degeneration of the organ of Corti, the spiral ganglion starts to degenerate from the midportion of the cochlea. However, even in adult cats (2 years), a sufficient number of functionally intact auditory afferents remain, which are suitable for electrical cochlear stimulation.

Acoustic Stimulation↗

Population statistics of protein structures: lessons from structural classifications.

Structural classifications aid the interpretation of proteins by describing degrees of structural and evolutionary relatedness. They have also recently revealed strikingly skewed distributions at all levels; for example, a small number of folds are far more common than others, and just a few superfamilies are known to have diverged widely. The classifications also provide an indication of the total number of superfamilies in nature.

Binding Sites↗

Hanbury Brown-Twiss correlations to probe the population statistics of GHz photons emitted by conductors.

We present the first study of the statistics of GHz photons in quantum circuits, using Hanbury Brown and Twiss correlations. The super-Poissonian and Poissonian photon statistics of thermal and coherent sources, respectively, made of a resistor and a radio frequency generator, are measured down to the quantum regime at milli-Kelvin temperatures. As photon correlations are linked to the second and fourth moments of current fluctuations, this experiment, which is based on current cryogenic electronics, may become a standard for probing electron/photon statistics in quantum conductors.

Journal Article↗

The problem of pressure sores in a nursing home population: statistical data.

This study on 93 patients was conducted at a skilled nursing facility. Twenty-two of the 93 patients had pressure sores; 34 of the 54 sores were present when the patients were admitted and 20 developed after admission. Only 5 of the 54 sores healed. Healing times ranged from 15 to 55 days after the beginning of treatment. Thirteen deaths occurred among the 71 patients without sores, and 17 deaths among the 22 patients with sores. Specific treatment regimens varied (cleaning solutions, antimicrobial drugs, heat, enzymatic debridement) but always included frequent changes in the position of the patient. Ten of the 22 patients with sores were anemic vs. 19 of the 71 patients without sores. Half of the patients with sores were maintained with tube feedings whereas more than half of the patients without sores received regular house diets. Pressure sores are a serious problem among geriatric patients in nursing homes. All those who care for the aged should be fully aware of the procedures involved in the prevention and management of these sores.

Adult↗

South American camelids in the United Kingdom: population statistics, mortality rates and causes of death.

A survey of the health of South American camelids in the United Kingdom was carried out between December 1992 and June 1993; 123 members of the British Camelid Owners and Breeders Association and 19 non-members were sent questionnaires and usable responses were received from 84 (59 per cent). In total 689 camelids were included, and in 1992, 66 per cent were Ilama, 21 per cent alpaca and 13 per cent guanaco. Their ages ranged from less than six months to over 10 years, with animals aged two to five years constituting the largest proportion. The mortality rates between 1990 and 1992 were 2.7 to 3.3 per cent for Ilama, 3.5 to 6.9 per cent for alpaca and 0 to 11.4 per cent for guanaco. The highest mortality was in animals less than six months and more than 10 years old; 4 to 11 per cent of Ilama deaths and 17 to 33 per cent of alpaca deaths were in animals aged less than six months and a high proportion of these occurred during the first week of life. In the cases for which a cause was reported, accidents and injury accounted for 20 per cent of Ilama deaths, and perinatal deaths accounted for 22 per cent of alpaca deaths. A third of the deaths were reported as being of unknown cause, and a veterinary diagnosis was reported in less than half of the cases. These data suggest that attention to the environment and housing conditions of Ilama, the neonatal care of alpaca and improvements in diagnosis are priorities for reducing the mortality and improving the health of South American camelids in the UK.

Animals↗