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Incorporating HIV test data into forecasts of the AIDS epidemic in Scotland.

For AIDS cases in Scotland the date of HIV antibody positive diagnosis (HIV test date) is recorded on the AIDS case reports. Data are also available on the total numbers of individuals with HIV positive test reports in Scottish laboratories in each year since testing became available. These data are incorporated into a model of the HIV epidemic described in terms of testing rates by calendar year. The HIV infection curve is modelled as a step function, and the testing rates are allowed to differ between steps. Results are presented for intravenous drug users (IDUs) and for homosexual/bisexual men. The estimated rates of testing for the IDUs (estimates from 19 per cent to 44 per cent per year) are considerably higher than those for homosexual/bisexual men (estimates of 10 per cent to 17 per cent per year). Data on the year of testing for AIDS diagnoses gave relatively little improvement in estimates of the HIV infection curve. However, when this information is combined with data on the total number of HIV positive diagnoses per year, there is a dramatic improvement in the estimate of the HIV infection curve. This is particularly marked for infections in the most recent period and for the estimates of cumulative infections up to the present. However, these improvements are gained at the cost of assumptions of similar testing rates applying to all sections of the HIV infected populations, which will be difficult to check in practice. This suggests that these methods should not be used in isolation but in combination with other evidence about the spread of HIV infection in a population.

Acquired Immunodeficiency Syndrome↗
PubMed2006

A temporal forecast of radiation environments for future space exploration missions.

The understanding of future space radiation environments is an important goal for space mission operations, design, and risk assessment. We have developed a solar cycle statistical model in which sunspot number is coupled to space-related quantities, such as the galactic cosmic radiation (GCR) deceleration potential (phi) and the mean occurrence frequency of solar particle events (SPEs). Future GCR fluxes were derived from a predictive model, in which the temporal dependence represented by phi was derived from GCR flux and ground-based Climax neutron monitor rate measurements over the last four decades. These results showed that the point dose equivalent inside a typical spacecraft in interplanetary space was influenced by solar modulation by up to a factor of three. It also has been shown that a strong relationship exists between large SPE occurrences and phi. For future space exploration missions, cumulative probabilities of SPEs at various integral fluence levels during short-period missions were defined using a database of proton fluences of past SPEs. Analytic energy spectra of SPEs at different ranks of the integral fluences for energies greater than 30 MeV were constructed over broad energy ranges extending out to GeV for the analysis of representative exposure levels at those fluences. Results will guide the design of protection systems for astronauts during future space exploration missions.

Computer Simulation↗
PubMed2003

Effect of air temperature on forecasting the start of the Betula pollen season at two contrasting sites in the south of Europe (1995-2001).

In order to survive periods of adverse cold climatic conditions, plant requirements are satisfied by means of physiological adaptations to prevent cells from freezing. Thus, the growth of woody plants in temperate regions slows down and they enter into a physiological state called dormancy. In order to identify the chilling and heat requirements to overcome the dormancy period of Betula in the south of Europe, a comparative study was carried out with aerobiological pollen data of a 7-year (1995-2001) period in Vigo (Spain) and Perugia (Italy). To satisfy chilling requirements, base temperatures of 7 degrees C and 5.75 degrees C showed a lower standard variation coefficient: 3.94% and 2.36% in Perugia and Vigo respectively. In the case of heat accumulation, the sum of mean temperatures in Perugia and the sum of maximum temperatures in Vigo were the parameters that showed a minor coefficient of variation (11.13% and 14.51% respectively).

Adaptation, Physiological↗
PubMed1987

Forecast of surgical risk in pancreatic cancer.

Over a 22 year period, 305 patients underwent operations for pancreatic cancer. Seventy-one patients who only underwent a laparotomy and 60 patients with defective data were excluded from our study. The remaining 174 patients were analyzed to find a clinically applicable algorithm to allow the preoperative surgical risk to be evaluated in a single patient. One hundred twenty-six had undergone a bypass operation (Group I) and 48, a potentially curative resection (Group II). The two groups were divided into the following three risk groups according to the postoperative course: D, patients who died during the first postoperative month; C, patients with postoperative complications; and U, patients with an uneventful course. Preoperative weight loss, duration of jaundice, serum bilirubin level, total protein level, and age of every patient were collected and transformed into a three-score ordinal scale. Stepwise discriminant analysis of these data enabled us to correctly classify 88 percent of the patients who underwent palliative operations and 83 percent of those who had pancreatic resection. This method is useful in identifying the risk group for a single patient using individual preoperative variables. It may, moreover, suggest the most suitable treatment for each patient with pancreatic cancer.

Adult↗
PubMed1991

Application of ARIMA models to forecast the quality of a French cheese: the 'Comté'.

In this paper, we present how we have established ARIMA models giving good predictions for the monthly percentage of Comté without making default for nine cooperatives of Jura (France). We detail how we have chosen the three parameters p, d, q of the ARIMA models for each cooperative and we present a method for selecting p and q based on information criteria. This method has also permitted to compare performances of different information criteria.

Cheese↗