Calendar Intervals Research Articles

Incidences of gliomas and meningiomas in Denmark, 1943 to 1997.

The objective of this study was to determine the nationwide, population-based incidences of intracranial gliomas and meningiomas (of all grades) during 55 years of monitoring in Denmark. On the basis of reports in the Danish Cancer Registry, we calculated age-standardized, period-specific incidences and age- and birth cohort-specific incidences, in 5-year age and calendar intervals, for intracranial gliomas and meningiomas. The incidence of gliomas increased 1.7-fold from 1943 to 1947 to 1993 to 1997, whereas the incidence for meningiomas increased 3.9-fold during the same period. Based on complete notification to the Danish Cancer Registry, the overall incidences of intracranial gliomas and meningiomas increased during a 55-year period. These increases were observed for all age groups and both sexes. These increases could be explained on the basis of improved diagnoses of these tumors. For gliomas, a maximal annual incidence of approximately 4 cases/100,000 population (World Standard Population) was observed in Denmark at the end of the study period, suggesting that the effects of improved diagnostic tools have reached their maximum with respect to this tumor type. The same was not observed for the incidence of meningiomas, suggesting that perhaps underreporting is still present.

Second nonbreast malignancies after conservative surgery and radiation therapy for early-stage breast cancer

Purpose : Breast cancer patients treated with conservative surgery and radiation therapy are at risk of developing second nonbreast malignancies (SNBMs). The purpose of this study was to determine the incidence of all SNBMs and SNBMs by specific location among long-term survivors and to compare the risk of these events to the age-specific incidence of malignances as first cancers in the Surveillance Epidemiology and End-Results Program (SEER) population. Methods and Materials : We analyzed the likelihood of SNBM development for 1884 patients with clinical Stage I or II breast cancer treated with gross excision and ≥60 Gy (median 63) to the breast between 1970 and 1987. Fifty-seven percent received supraclavicular/axillary radiation (median dose 45 Gy, range 20–60) and 28% received systemic therapy. The median age at diagnosis was 52 years. The median clinical tumor size was 2 cm. Patients were considered at risk of an SNBM until the development of the first of distant metastases or contralateral breast cancer or death or, if alive and disease-free, until the last follow-up visit. The expected numbers of cancers were obtained from the SEER database, using the age-specific incidence for white women within 5-year age groups and 5-year calendar intervals. The median time at risk for an SNBM was 10.9 years (range 0.2–27.9). Results : By 8 years of follow-up, 432 patients (23%) had developed distant metastases, 295 patients (16%) a local/regional recurrence, and 159 (8%) a contralateral primary. Of the 1884 patients in our cohort, 147 (8%) developed an SNBM compared with the 127.7 expected from SEER. This corresponds to an absolute excess of 1% of the study population and a relative increase of 15% greater than that expected from SEER ( p = 0.05). Within the first 5 years, the observed and expected rates of SNBMs were identical (47 vs. 46.9). After 5 years, 24% more SNBMs were observed than expected (100 vs. 80.8, p = 0.02). Among patients <50 years old at breast cancer diagnosis, 43% more observed SNBMs occurred than expected (40 vs. 28, p = 0.02). For patients ≥50 years, 7% more SNBMs were observed than expected (107 vs. 99.7, p = 0.25). Lung SNBMs were observed in 33 women, 52% more than the 21.67 predicted by SEER ( p = 0.01). Most of the lung SNBMs occurred >5 years after treatment ( n = 23) and in women who were >50 years at the time of their breast cancer diagnosis ( n = 27). The observed incidence of ovarian cancer was significantly greater than expected among patients <50 years (7 vs. 1.96, p = 0.004) but was not different than expected for patients ≥50 years (5 vs. 5.3, p = 0.61). Among the 7 sarcomas, 3 developed in the radiation field. Conclusions : SNBMs occur in a substantial minority (8%) of patients treated with conservative surgery and radiotherapy. However, the absolute excess risk compared with the general population is very small (1%). This excess risk is only evident after 5 years. In particular, a slightly increased incidence of lung SNBMs and a somewhat larger increase in ovarian cancer among younger patients was found. Our data suggest that preventive strategies to reduce the incidence of certain cancers (e.g., smoking cessation and prophylactic oophorectomy) and/or continued monitoring for SNBMs to increase the likelihood of early detection and treatment may be prudent in this population.

The relationship of pregnancy to the use of highly active antiretroviral therapy

Objective: Public health agencies have recommended that the criteria for the use of highly active antiretroviral therapy should not be modified because of pregnancy. However, little information has been published with regard to the degree to which these recommendations are being followed. We report here the frequency of highly active antiretroviral therapy use among pregnant women in the Women’s Interagency HIV Study and compare the frequencies of its use by pregnant women meeting published criteria for implementing highly active antiretroviral therapy and its use by nonpregnant women meeting the same criteria. Study Design: From October 1994 through November 1995, a total of 2059 human immunodeficiency virus type 1–seropositive women were enrolled in a cohort study. Participants were evaluated at baseline and at 6-month intervals with standardized interview instruments. In addition to a general physical examination at each visit, patients had a urine pregnancy test performed and were asked about current pregnancies, pregnancies since the last visit, and which antiretroviral medications they had used since the last visit. Highly active antiretroviral therapy was defined according to 1997 National Institutes of Health guidelines. Result: At each calendar interval after October 1996, a greater proportion of nonpregnant women than pregnant women reported the use of highly active antiretroviral therapy. The use of monotherapy declined for both groups during the course of multiple calendar periods (P < .01), although the use of monotherapy remained higher among the pregnant women. In any given calendar period, pregnant women meeting published criteria for highly active antiretroviral therapy use were slightly less likely than similar nonpregnant women to receive highly active antiretroviral therapy (odds ratio, 0.28-0.98). Because of the sample size these differences reached significance in only one calendar period (P = .02). With time pregnant women did demonstrate an increase in the percentage receiving highly active antiretroviral therapy. In nearly all calendar periods a larger percentage of pregnant than nonpregnant women were receiving a regimen that included zidovudine. Conclusions: Highly active antiretroviral therapy is being received by an increasing percentage of women who meet published criteria for its use, and pregnancy is a relatively small impediment to its use. Further efforts are needed to bolster the use of highly active antiretroviral therapy by all appropriate candidates and to ensure equal access to this therapy for pregnant women. Because of the increasingly frequent use of highly active antiretroviral therapy during pregnancy, ongoing efforts are needed to monitor any long-term effects of in utero exposure to multiple antiretroviral agents. (Am J Obstet Gynecol 2001;184:1221-7.)

A MATHEMATICAL THEOREM TO RELATE SEASONAL DRY MATTER TO HARVEST INTERVAL FOR THE EXPANDED GROWTH MODEL1*

The expanded growth model has proven very useful for describing accumulation of dry matter by forage grasses with time. This includes both annuals such as corn (Zea mays) and perennials such as bermudagrass (Cynodon dactylon), bahiagrass (Paspalum notatum), and tall fescue (F. arundinacea Schreb.). Analysis of field data for perennials has shown that normalized dry matter distribution follows the probability function and that seasonal dry matter yield follows a linear-exponential function of harvest interval. The mathematical basis for these facts has not been clear. This article presents a mathematical theorem which gives a more rigorous foundation for both of these observations, and clearly demonstrates the dependence of the model on both calendar time and harvest interval. * Florida Agricultural Experiment Station Journal Series No. R-07341.

Breastfeeding and the risk of life-threatening enterotoxigenic Escherichia coli diarrhea in Bangladeshi infants and children.

To assess the relationship between breastfeeding and the risk of life-threatening enterotoxigenic Escherichia coli (ETEC) diarrhea among Bangladeshi infants and young children <36 months of age. Case-control study. A rural Bangladesh community. A total of 168 cases with clinically severe ETEC diarrhea detected in a treatment center-based surveillance system during 1985 to 1986 and 3679 controls selected in three surveys of the same community during the same calendar interval. Cases and controls were compared for the frequency of antecedent breastfeeding patterns. Compared with other feeding modes, exclusive breastfeeding of infants was associated with significant protection against severe ETEC diarrhea (relative risk [RR] = 0.51; 95% confidence interval [CI]: 0.28,0.96). However, during the second and third years of life, the risk of this outcome was similar in both breastfed and nonbreastfed children (RR = 0.98; 95% CI: 0.45,2.12), and no significant overall protective association between breastfeeding and severe ETEC diarrhea was evident during the first 3 years of life (RR = 0.86; 95% CI: 0.43,1. 74). Exclusive breastfeeding appeared to protect infants against severe ETEC diarrhea, but breastfeeding was not associated with protection after infancy, nor was it associated with a major overall reduction of severe ETEC disease during the first 3 years of life. Although not diminishing the importance of breastfeeding, our findings suggest that other interventions, such as immunization and education about proper food hygiene, may also be required in efforts to prevent this major pediatric disease.

Efficacy of insecticidal applications based on calendar intervals and plant growth stages for control of insect pests on cowpea

AbstractStudies were carried out to compare the efficacy of insecticide schedules based on calendar intervals with those based on plant growth stages for the control of cowpea insect pests. Spray schedules based on calendar intervals and plant growth stage gave reasonable control of the pest complex and increased grain yields significantly. However, spray schedules based on plant growth stages alone were more efficient for two of the three cowpea varieties tested. This was attributed to differences in maturity periods which made spraying by regular calendar intervals slightly out of phase with attack by key insect pests. Thus, spray schedules based on plant growth stages are recommended for the control of insect pests of cowpea.

Radiocarbon Dating Sites of Northwest Russia and Latvia

We describe applications of radiocarbon dating used for establishing a chronology of archaeological sites of the Novgorod region at the end of the first millennium ad. We have 14C-dated known-age tree rings from sites in Latvia and ancient Novgorod, northwest Russia, as well as charcoal and wood from Novgorod. Calendar ages of 14C-dated tree rings span the interval, ad 765–999. We used the Groningen calibration program, CAL15 (van der Plicht 1993) to calibrate 14C ages to calendar years. Comparisons between 14C results and archaeological data show good agreement, and enable us to narrow the calendar interval of calibrated 14C determinations.

Breast-Feeding and the Risk of Life-Threatening Rotavirus Diarrhea: Prevention or Postponement?

To assess the relationship between breast-feeding and the risk of life-threatening rotavirus diarrhea among Bangladeshi infants and children younger than 24 months of age. Case-control study. A rural Bangladesh community. One hundred two cases with clinically severe rotavirus diarrhea detected in a treatment center-based surveillance system during 1985 and 1986, and 2587 controls selected in three surveys of the same community during the same calendar interval. Cases and controls were compared for the frequency of antecedent breast-feeding patterns. Compared with other feeding modes, exclusive breast-feeding of infants was associated with significant protection against severe rotavirus diarrhea (relative risk (RR) = 0.10; 95% confidence interval [CI] = 0.03, 0.34). However, during the second year of life, the risk of this outcome was higher in breast-fed than in non-breast-fed children (RR = 2.85; 95% CI = 0.37, 21.71), and no overall protection was associated with breast-feeding during the first 2 years of life (RR = 2.61; 95% CI = 0.62, 11.02). Although exclusive breast-feeding appeared to protect infants against severe rotavirus diarrhea, breast-feeding per se conferred no overall protection during the first 2 years of life, suggesting that breast-feeding temporarily postponed rather than prevented this outcome. While not detracting from efforts to promote breast-feeding to alleviate the burden of diarrhea due to nonrotaviral enteropathogens, our findings cast doubt on whether such efforts will impact on the problem of severe rotavirus diarrhea.

Neonatal and infancy time scale for extension into childhood and adulthood

A logarithmic time scale is presented for exposition of clinical events and related data on a unified scale extending from neonatal time into childhood and adulthood. Such a scale preserves time scale proportions but has the advantage for certain applications of featuring early neonatal and infancy events. This type of time base avoids the disadvantages of a crowded and obscured linear scale or an arbitrary and non-unified split time scale. For clinical application all timed events are initially converted to a common unit such as days. A visually comprehensible logarithmic time scale can be derived by plotting the logarithmic scale (labeled in days, base 2) and then establishing conventional calendar interval marks (weeks, months, years) and the data plot points. A simple equation is presented for establishing the time scale graph markers and the plot data points for a logarithmic time scale of any scale axis length.

Effects of Rainfall and Temperature Interactions During the Growing Season on Corn Yield1

AbstractMaximum daily temperatures and rainfall were found to have a large effect on corn yield from 25 days before to 15 days after anthesis. This corresponds to the average calendar interval of June 30 through August 8 at Urbana. The maximum effect of temperature and rainfall on corn yield occurs approximately one week before anthesis and remains at a high level one week to either side of the maximum. The models solved in this investigation indicate that high temperatures (maximum daily temperatures between 32.2 and 37.8 C or 90 and 100 F) can be beneficial to corn yield if moisture available to the corn plant is adequate.