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Secular Trend (secular + trend)

Distribution by Scientific Domains

Medical Sciences	53%
Life Sciences	27%
Earth and Environmental Science	7%
Business, Economics, Finance and Accounting	6%
3 Other Domains	7%

Distribution within Medical Sciences

Pediatrics	22%
Neurology	7%
General & Internal Medicine	5%
13 Other Subdomains	66%

Selected Abstracts

Secular Trends in the Incidence of Female Breast Cancer in the United States, 1973,1998

THE BREAST JOURNAL, Issue 2 2004
Kiumarss Nasseri DVM
Abstract: , Statistical modeling suggests a causal association between the rapid increase in the incidence of female breast cancer (FBC) in the United States and the widespread use of screening mammography. Additional support for this suggestion is a shift in the stage at diagnosis that consists of an increase in early stage diagnosis followed by a decrease in late-stage diagnosis. This has not been reported in the United States. The objective of this study was to examine the secular trends in the incidence of FBC in search of empirical support for this shift. FBC cases in the Surveillance, Epidemiology, and End Results (SEER) database from 1973 through 1998 were dichotomized into early and late detection based. Early detection included all the in situ and invasive cases with local spread. Late detection included cases with regional spread and distant metastasis. Joinpoint segmented regression modeling was used for trend analysis. Early detection in white and black women followed a similar pattern of significant increase in the early 1980s that continued through 1998 with slight modification in 1987. The expected shift in stage was noticed only for white women when the incidence of late detection in them began to decline in 1987. The incidence of late detection in black women has remained stable. These results provide further support for the previously implied causal association between the use of screening mammography and the increased incidence of FBC in the United States. It also shows that the expected stage shift appeared in white women 50,69 years of age after an estimated detection lead time (DLT) of about 5 years. This is the first estimate of DLT in the United States that is based on actual data. The subsequent increase in late detection in white women since 1993 may be due to changes in case management and the increased use of sentinel lymph node biopsy (SLNB) rather than changes in the etiology or biology of FBC., [source]

Secular trend of age-specific prevalence of hepatitis B surface and e antigenemia in pregnant women in Taiwan

JOURNAL OF MEDICAL VIROLOGY, Issue 4 2003
Ho-Hsiung Lin
Abstract To elucidate the impact of aging of hepatitis B carrier women on their viral replicative markers in a hepatitis B endemic area, all the parturients admitted to the Hospital were studied from 1985 to 2000. Serum hepatitis B surface (HBsAg) and hepatitis B e antigen (HBeAg) were tested by radioimmunoassay. Mann-Whitney U and Student's t -tests were used for statistical analysis. The results showed the yearly prevalence rate of HBsAg in pregnant women seemed stable with a mean of 12.0,±,1.1% during the period. The yearly positive rate of HBeAg among HBsAg-positive pregnant women varied between 30.4% and 42.6% from 1985 to 1992 and declined from 29.6% in 1993 to 18.1% in 2000. The mean ratio of HBeAg/HBsAg in carrier parturients was 24.7% [intraquantile range (IQR) 20.5,28.4] from 1993 to 2000, which was significantly lower than that of 32.4% (IQR 31.0,39.0) from 1985 to 1992 (P,< 0.0001). The mean age of HBeAg-positive primiparas from 1993 to 2000 was 29.1,±,3.9 years and significantly higher than that of 28.0,±,3.7 years from 1985 to 1993 (P,<,0.001), as well as in secundiparas 31.2,±,3.8 years vs. 30.1,±,3.4 years (P,< 0.001) and in total parturients 30.3,±,4.2 years vs. 29.3,±,3.8 years (P,<,0.001). Thus, no significant decrease of HBsAg carriage was observed in the past 16 years, whereas a decreased ratio of HBeAg/HBsAg was noted in carrier parturients in the past 8 years and the elderly HBeAg-positive parturients from 1993 to 2000 may be the cause. J. Med. Virol. 69:466,470, 2003. © 2003 Wiley-Liss, Inc. [source]

Secular trend in medical education regarding infectious disease

MEDICAL EDUCATION, Issue 10 2003
Kai Ming Chow
Objective ,The paradigm of global medical health has been re-characterised by a shift in its major focus from infectious disease to chronic illness. Opinions vary as to the declining emphasis on infectious disease. This paper provides clinicians with an understanding of a secular trend in medical education regarding the topic of infectious diseases over a period of 26 years. Methods ,A survey was carried out to evaluate coverage of infectious disease topics within recent general medicine textbooks and journals. Results ,The percentage of content dedicated to infectious disease has remained static in 2 major medical textbooks, whereas a trend towards decreasing coverage was shown in 4 major medical journals. Of 901 original articles published in 2000, 16·4% covered certain aspects of infectious disease, as compared with 20·9% of 790 articles published in 1985. Increasing rates of infectious disease mortality in developing countries were not consistently matched with the trend in coverage of infectious disease topics in either medical textbooks or journals. Conclusions ,Our data demonstrate that coverage of infectious disease topics in publications issued in developed countries was more indicative of global trends in disease mortality rather than those of developing countries. Medical education and knowledge, which are usually delivered by the rich nations where influential medical textbooks and journals are published, place less emphasis on infectious disease relative to the burden infectious disease places on the developing world. [source]

Secular trend in age at menarche in indigenous and nonindigenous women in Chile

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010
X.M. Ossa
Objectives: To estimate the secular trend in age at menarche, comparing indigenous and nonindigenous women, and its relationship with socio-demographic, family and nutritional factors. Methods: A study (historical cohorts) of 688 indigenous and nonindigenous women, divided into four birth cohorts (1960,69, 1970,79, 1980,89, and 1990,96) in an area in central southern Chile was carried out. Data and measurements were collected by health professionals using a previously validated questionnaire. Age at menarche was self-reported (recall). Adjusted differences among cohorts were estimated using a multivariate regression model. Results: A secular trend (P < 0.001) in age at menarche was found in both ethnic groups, with no significant differences between them (P > 0.05). In an adjusted model, a reduction in age at menarche was estimated at 3.7 months per decade between 1960 and 1990. This trend was moderated by higher socio-economic level, smaller number of siblings, and cohabitation with a single parent during infancy. Conclusions: The trend has occurred in a steady progression over time in indigenous women, whereas in nonindigenous women, it was slow initially but has accelerated in recent years. Nonindigenous women have maintained a slightly lower age of menarche than their indigenous counterparts. Am. J. Hum. Biol. 22:688-694, 2010. © 2010 Wiley-Liss, Inc. [source]

Secular trend in peak oxygen consumption among United States youth in the 20th century

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2002
Joey C. Eisenmann
The purpose of this study was to examine secular change in peak oxygen consumption (Vo2) in U.S. boys and girls using available data from the 20th century. Studies were primarily identified from review articles and a Medline search. To be included in the analysis, studies must have included direct measurement of peak Vo2 on healthy (free from overt disease) United States children and youth from the general population separated by sex. Data (mean values) were divided by decade and separated into three age groups: 6,12, 13,15, and 16,18 years for boys, and 6,11, 12,14, and 15,18 years for girls. Peak Vo2 values were expressed as related to bipedal locomotion; therefore, cycle ergometry values were corrected by a factor of 1.075. Mean values were fit by least squares, goodness-of-fit regression lines. Results indicate that absolute (L·min,1) and relative (ml·kg,1·min,1) peak Vo2 have remained relatively stable among boys and young girls. In adolescent girls, particularly those 15 years of age and older, peak Vo2 has decreased by approximately 20% over the past few decades. The available data indicate that aerobic fitness has not decreased in United States youth except in adolescent girls over the past few decades. Am. J. Hum. Biol. 14:699,706, 2002. © 2002 Wiley-Liss, Inc. [source]

Cerebral palsy and newborn care: I, II, and III (1981)

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 12 2008
Fiona Stanley MD
Another in our series of commentaries on notable papers from the DMCN archives. The full papers are available at http://www.mackeith.co.uk Kiely JL, Paneth N, Stein Z, Susser M. Cerebral palsy and newborn care. I: Secular trends in cerebral palsy. Dev Med Child Neurol 1981; 23: 533,38. Kiely JL, Paneth N, Stein Z, Susser M. Cerebral palsy and newborn care. II: Mortality and neurological impairment in low-birthweight infants. Dev Med Child Neurol 1981; 23: 650,59. Kiely JL, Paneth N, Stein Z, Susser M. Cerebral palsy and newborn care. III: Estimated prevalence rates of cerebral palsy under differing rates of mortality and impairment of low-birthweight infants. Dev Med Child Neurol 1981; 23: 801,07. [source]

Secular trends, disease maps and ecological analyses of the incidence of childhood onset Type 1 diabetes in Northern Ireland, 1989,2003

DIABETIC MEDICINE, Issue 3 2007
C. R. Cardwell
Abstract Aims To investigate secular trends in the incidence of Type 1 diabetes in Northern Ireland over the period 1989,2003. To highlight geographical variations in the incidence of Type 1 diabetes by producing disease maps and to compare incidence rates by relevant area characteristics. Methods New cases of Type 1 diabetes in children aged 0,14 years in Northern Ireland were prospectively registered from 1989 to 2003. Standardized incidence rates were calculated and secular trends investigated. Bayesian methodology was used to produce maps of disease incidence using small geographical areas (582 electoral wards). Ecological analyses were conducted using Poisson regression to investigate incidence rates by area characteristics at a finer geographical subdivision (5022 census output areas). Results In Northern Ireland during 1989,2003, there were 1433 new cases, giving a directly standardized incidence rate of 24.7 per 100 000 person-years. This incidence rate increased by a mean of 4.2% per annum. Disease maps highlighted higher incidence rates in the predominately rural north-east of the province and lower incidence rates in the urban areas around Belfast in the east and Derry in the north-west of the province. Ecological analysis identified higher incidence in rural areas (P < 0.001), areas with low migration rates (P = 0.002), affluent areas (P < 0.0001), sparsely populated areas (P = 0.0001) and remote areas (P = 0.005). Conclusions In Northern Ireland the incidence of Type 1 diabetes is increasing. The observed higher incidence in rural, affluent, sparsely populated and remote areas may reflect a reduced or delayed exposure to infections in these areas. [source]

The ,oestrogen hypothesis', where do we stand now?,

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 1 2003
Richard M. Sharpe
Summary The original ,oestrogen hypothesis' postulated that the apparent increase in human male reproductive developmental disorders (testis cancer, cryptorchidism, hypospadias, low sperm counts) might have occurred because of increased oestrogen exposure of the human foetus/neonate; five potential routes of exposure were considered. This review revisits this hypothesis in the light of the data to have emerged since 1993. It addresses whether there is a secular increasing trend in the listed disorders and highlights the limitations of available data and how these are being addressed. It considers whether new data has emerged to support the suggestion that increased oestrogen exposure could cause these abnormalities and reviews new data on potential routes via which such increased exposure could have occurred. Secular trends: The disorders listed above are now considered to represent a syndrome of disorders (testicular dysgenesis syndrome, TDS) with a common origin in foetal life. Testicular cancer has increased in incidence in Caucasian men worldwide and lifetime risk is 0.3,0.8%. Secular trends in cryptorchidism are unclear but it is by far the commonest (2,4% at birth) congenital abnormality in either sex. Secular trends for hypospadias are not robust, although most studies suggest a progressive increase; registry data probably under-estimates incidence, but based on this data hypospadias is the second most common (0.3,0.7% at birth) congenital malformation. Retrospective analyses of sperm count data show a global downward trend but this is inconclusive , prospective studies using standardized methodology show significant differences between countries and very low sperm counts in the youngest cohort of men. For all disorders, other then testis cancer, standardized prospective studies are the best way forward and are in progress across Europe. Oestrogen effects: Evidence that foetal exposure to oestrogens can induce the above disorders has strengthened. New pathways via which such changes could be induced have been identified, including suppression of testosterone production by the foetal testis, suppression of androgen receptor expression and suppression of insulin-like factor-3 (InsL3) production by foetal Leydig cells. Other evidence suggests that the balance between androgen and oestrogen action may be important in induction of reproductive tract abnormalities. Oestrogen exposure: Although many new environmental oestrogens have been identified, their uniformly weak oestrogenicity excludes the possibility that they could induce the above disorders. However, emerging data implicates various environmental chemicals in being able to alter endogenous levels of androgens (certain phthalates) and oestrogens (polychlorinated biphenyls, polyhalogenated hydrocarbons), and the former have been shown to induce a similar collection of disorders to TDS. Other mechanisms via which increased fetal exposure to pregnancy oestrogens might occur (increasing trend in obesity, dietary changes) are also discussed. [source]

Is the Prevalence of Paget's Disease of Bone Decreasing?,

JOURNAL OF BONE AND MINERAL RESEARCH, Issue S2 2006
Tim Cundy
Abstract Secular trends in the severity and prevalence of Paget's disease over a 30-year period are described. Paget's disease has become less prevalent and patients are presenting later, with less severe disease than previously. These data suggest that environmental factors are important in the etiology of Paget's disease. Introduction: Data from several countries support the view that there are important secular trends in the prevalence and severity of Paget's disease. In this paper, recent trends in the epidemiology of Paget's disease are described. Materials and Methods: A database of all newly referred patients (n = 1487) with Paget's disease (1973,2002 inclusive, 30 years) was examined. Of these subjects, 56% had scintiscans. Plasma total alkaline phosphatase (total ALP) activity and disease extent on scintiscan were used as indices of severity. A radiographic prevalence survey of 1019 subjects of European origin >55 years of age in Dunedin was undertaken,,20 years after an earlier survey had shown New Zealand to be a high prevalence area. Results: The number of new referrals with Paget's disease declined sharply from 1994 onward, to one half the rate seen 20 years earlier, whereas the mean age at presentation increased by 4 years per decade (p < 0.0001). Total ALP at diagnosis, disease extent on scintiscan, and the number of bones involved were all negatively correlated with both date of birth (p < 0.0001) and year of presentation (p < 0.0001), indicating that more recently born and presenting subjects had substantially less severe bone disease. The radiographic survey showed that the current prevalence was only ,50% of that in the 1983 survey (p = 0.012). Conclusions: Although there are a number of potential biases, these data are consistent with a continued secular trend to presentation in older subjects with less extensive skeletal involvement and a declining prevalence of Paget's disease. [source]

Secular trends in socio-economic status and the implications for preterm birth

PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 3 2006
John M. D. Thompson
Summary The rate of preterm birth in the developed world has been shown to be increasing, in part attributable to obstetric intervention. It has been suggested that this may be a differential increase between socio-economic groups. We aimed to assess whether the preterm rate in Norway is different in socio-economic groups defined by maternal education, and to determine the extent to which a difference is attributable to a socio-economic differential in obstetrical intervention, in terms of caesarean section or induction of labour. We used data from the Medical Birth Registry of Norway from 1980 to 1998 with preterm rate as the outcome and maternal educational level, marital status and obstetric intervention as exposure variables. In multivariable analyses, adjustment was made for maternal age, year of birth and birth order, and secular trends were assessed according to year of birth. The preterm birth rate was highest in the lowest socio-economic group. An increase of 25.2% in the preterm rate was seen over the observation period. No apparent differential was seen in the increase of the crude preterm rates between socio-economic groups, although in multivariable analyses there was a significant interaction between socio-economic group and time, implying a stronger effect of low education towards the end of the observation period attributable to demographic change. In conclusion, the preterm birth rate increased over time, but was mainly due to an increase in obstetric interventions. No closing of the gap between socio-economic groups was observed. [source]

Secular trends of hypospadias prevalence and factors associated with it in southeast China during 1993,2005

BIRTH DEFECTS RESEARCH, Issue 6 2010
Lei Jin
Abstract BACKGROUND The aim of this study is to describe the prevalence of hypospadias and its time trends during 1993,2005 in southeast China, and to explore the potential risk factors. METHODS The study population included all male live and still births (at least 20 weeks of gestation) in 11 cities and counties in Jiangsu and Zhejiang Provinces in Southeast China born during January 1, 1993, through December 31, 2005. RESULTS Overall prevalence of hypospadias was 5.8 per 10,000 male births and presented an increasing trend during 1993,2005 (with , of 3.94, p = 0.047). Prevalence of coronal hypospadias and those with unknown sites increased from 1.7 and 0.3 per 10,000 male births in 1993 to 3.6 and 1.4 per 10,000 male births in 2005, respectively (with , of 7.29 and 9.05, p = 0.007 and p = 0.002, respectively), but prevalence of perineal hypospadias decreased (with , of 7.13, p = 0.008). Maternal fever during first trimester, birth of twins or more children, and year of birth were independent risk factors for hypospadias, with odds ratios of 4.14 (95% CI, 1.32,12.83), 3.37 (95% CI, 1.73,6.58), and 1.04 (95% CI, 1.00,1.08), respectively, after adjusting for confounding factors with multivariable logistic regression analysis. CONCLUSIONS Prevalence of hypospadias increased during 1993,2005 in the two provinces in southeast China. Maternal fever in the first trimester and birth of twins or more children are associated with the risk for hypospadias. Birth Defects Research (Part A), 2010. © 2010 Wiley-Liss, Inc. [source]

Overweight and obesity in Norwegian children: Secular trends in weight-for-height and skinfolds

ACTA PAEDIATRICA, Issue 9 2007
PB Júlíusson
Abstract Aim: The prevalence of overweight and obesity in paediatric populations has been rapidly increasing in many countries over the past decades. The aims of the present study were to provide new data on weight-for-height and skinfolds, and to compare these to growth references for children between 3 and 17 years, collected in the same city between 1971 and 1974. Material: The present study is based on cross-sectional data of 4115 children (2086 boys and 2029 girls) aged 4,15 years measured in 2003,6. Results: Overall, 18.0% of the boys and 20.1% of the girls were above the 90th weight-for-height percentile of the 1971,1974 references, 8.0% and 7.2% were above the 97.5th percentile, indicating an upward shift in weight-for-height. An even more prominent increase was observed for skinfold thicknesses; for triceps skinfolds about 30% of the boys and 28% of the girls were above the 90th percentile of the 1971,1974 references, and corresponding values for subscapular skinfolds were 26.5% and 25.9%. Using international cut-off values for body mass index, the overall prevalence of overweight and obesity was 12.5% and 2.1% in boys, and 14.8% and 2.9% in girls. Conclusions: Our study has demonstrated a significant increase in weight-for-height in Norwegian children over the last 30 years, and that these changes are caused by an increase in fat tissue, as shown by skinfold measurements. The current prevalence of overweight and obesity is comparable to recent estimates from most Western and Northern European countries. [source]

Secular trends in nosocomial candidaemia in non-neutropenic patients in an Italian tertiary hospital

CLINICAL MICROBIOLOGY AND INFECTION, Issue 11 2005
R. Luzzati
Abstract A retrospective study was performed in an Italian tertiary hospital to evaluate trends in candidaemia between 1992 and 2001, and to compare the characteristics of episodes of fungaemia between 1992,1997 and 1998,2001. In total, 370 episodes of candidaemia were identified, with an average incidence of 0.99 episodes/10 000 patient-days/year (range 0.49,1.29 episodes). On an annual trend basis, the overall incidence was essentially stable in surgical and medical wards, but decreased in intensive care units (ICUs) (p 0.0065). The average use of fluconazole was 37.9 g/10 000 patient-days/year (range 21.4,56.1 g), and did not change significantly during the 10-year period. Nearly two-thirds of patients were in ICUs at the onset of candidaemia, but none was neutropenic in either study period. Candida albicans remained the predominant species isolated (53.8% vs. 48.1%), followed by Candida parapsilosis, Candida glabrata and Candida tropicalis, the distribution of which did not change significantly. The 30-day crude mortality rate was essentially similar (44% vs. 35%) in both study periods. Thus the incidence of nosocomial candidaemia, although high in this institution, decreased among critically-ill patients during the 10-year period. This finding seemed to be related to an improvement in infection control practices, particularly regarding the prevention of intravascular catheter-related infections in ICUs. Although the overall use of fluconazole was considerable, no increase in azole-resistant non- albicans Candida spp. was detected. [source]

New reference for the age at childhood onset of growth and secular trend in the timing of puberty in Swedish

ACTA PAEDIATRICA, Issue 6 2000
YX Liu
The objectives of the present work were to present a new reference for the age at childhood onset of growth and to investigate the secular trend in the timing of puberty in a community-based normal population in Sweden. A total of 2432 children with longitudinal length/height data from birth to adulthood were used to determine the two measures by visual inspection of the measured attained length/height and the change in growth velocity displayed on a computer-generated infancy-childhood-puberty (ICP) based growth chart. The series represents a sample of normal full-term children born around 1974 in Göteborg, Sweden. We found about 10% of children were delayed (>12 mo of age) in the childhood onset of growth based on the previous reported normal range, i.e. 14% in boys and 8% in girls. Distribution of the age at childhood onset of growth was skewed. The medians were 10 and 9 mo for boys and girls, respectively. After natural logarithmic transformation, the mean and standard deviation (SD) were 2.29 (anti-log 9.9 mo) and 0.226 for boys, 2.23 (anti-log 9.3 mo) and 0.220 for girls, respectively. The 95% normal ranges were 6.3-15.4 and 6.0-14.3 for boys and girls, respectively. The distribution of the timing of PHV was close to the normal distribution. The mean values were 13.5 y for boys and 11.6 y for girls with 1 y SD for both sexes. Conclusion: A downward secular trend in the onset of puberty was clearly shown in the population. The age at childhood onset of growth did not correlate with the timing of puberty (r=,0.01 and 0.05, p > 0.7 and 0.1 in boys and girls, respectively). Normal ranges of the age at childhood onset of growth are in need of revise, as this study indicates. The new reference presented here could be a reliable indicator in further studies. [source]

Surface deformation induced by present-day ice melting in Svalbard

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 1 2009
H. P. Kierulf
SUMMARY The vertical movement of the Earth's surface is the result of a number of internal processes in the solid Earth, tidal forces and mass redistribution in the atmosphere, oceans, terrestrial hydrosphere and cryosphere. Close to ice sheets and glaciers, the changes in the ice loads can induce large vertical motions at intraseasonal to secular timescales. The Global Positioning System (GPS) and Very Long Baseline Interferometry (VLBI) antennas in Ny-Ålesund, Svalbard that started observations in 1991 and 1995, respectively, observe vertical uplift rates on the order of 8 ± 2 mm yr,1, which are considerably larger than those predicted by postglacial rebound (PGR) models (order 2 mm yr,1). The observations also indicate increased uplift rates starting some time in 2000. A local GPS campaign network that has been reoccupied annually since 1998, reveals a tilting away from the neighbouring glaciers. The Svalbard glaciers have been undergoing melting and retreat during the last century, with increased melting since about 2000. We compared the observed vertical motion to the motion predicted by loading models using a detailed ice model with annual time resolution as forcing. The model predictions correlate well with the observations both with respect to the interannual variations and the spatial pattern of long-term trends. The regression coefficients for predicted and observed interannual variations in height is 1.08 ± 0.38, whereas the regression coefficient for the predicted and observed spatial pattern turns out to be 1.26 ± 0.42. Estimates of the predicted secular trend in height due to PGR and present-day melting are on the order of 4.8 ± 0.3 mm yr,1 and thus smaller than the observed secular trend in height. This discrepancy between predictions and observations is likely caused by the sum of errors in the secular rates determined from observations (due to technique-dependent large-scale offsets) and incomplete or erroneous models (unaccounted tectonic vertical motion, errors in the ice load history, scale errors in the viscoelastic PGR models and the elastic models for present-day melting). [source]

Variations in the Earth's gravity field caused by torsional oscillations in the core

GEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2004
Mathieu Dumberry
SUMMARY We investigate whether a component of the flow in the Earth's fluid core, namely torsional oscillations, could be detected in gravity field data at the surface and whether it could explain some of the observed time variations in the elliptical part of the gravity field (J2). Torsional oscillations are azimuthal oscillations of rigid coaxial cylindrical surfaces and have typical periods of decades. This type of fluid motion supports geostrophic pressure gradients, which produce deformations of the core,mantle boundary. Because of the density discontinuity between the core and the mantle, such deformations produce changes in the gravity field that, because of the flow geometry, are both axisymmetric and symmetric about the equator. Torsional oscillations are thus expected to produce time variations in the zonal harmonics of even degree in the gravity field. Similarly, the changes in the rotation rates of the mantle and inner core that occur to balance the change in angular momentum carried by the torsional oscillations also produce zonal variations in gravity. We have built a model to calculate the changes in the gravity field and in the rotation rates of the mantle and inner core produced by torsional oscillations. We show that the changes in the rotation rate of the inner core produce changes in J2 that are a few orders of magnitude too small to be observed. The amplitudes of the changes in J2 from torsional oscillations are 10 times smaller than the temporal changes that are observed to occur about a linear secular trend. However, provided the mechanism responsible for these changes in J2 is identified and that this contribution is removed from the data, it may be possible in the future to detect the lowest harmonic degrees of the torsional oscillations in the gravity field data. We also show that torsional oscillations have contributed to the linear secular change in J2 by about ,0.75 × 10,12 per year in the last 20 years. Finally, the associated change in the vertical ground motion at the surface of the Earth that is predicted by our mechanism is of the order of 0.2 mm, which is too small to be detected with the current precision in measurements. [source]

The impact of the Occupation of Guernsey 1940,1945 on breast cancer risk factors and incidence

INTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 6 2007
I. S. Fentiman
Summary To examine the impact of the German Occupation of Guernsey (1940,1945) on breast cancer risk factors and incidence. Under study were 1019 women who stayed, or whose mothers had stayed, in Guernsey, and 1358 women evacuated or born to evacuated mothers. Amongst those born 1926,1934 who remained in Guernsey, the secular trend of earlier menarche disappeared: menarche was delayed by 12 months for those born in 1930. By March 2006, 97 breast cancers had been diagnosed, 37 in the occupied group. Unusually, higher age at menarche appeared to be associated with increased risk of breast cancer (,14 years vs. ,13 years: HR = 1.52, 95% CI = 0.80,2.92). Separate analyses by birth cohort revealed a non-significantly higher incidence in the subgroup born from 1926 to 1934 (HR = 1.30, 95% CI = 0.62,2.76). Delay in menarche among women remaining in Guernsey during the Occupation, rather than being protective, was associated with an increased risk of breast cancer. [source]

Is the Prevalence of Paget's Disease of Bone Decreasing?,

Second Generation Models of Currency Crises

JOURNAL OF ECONOMIC SURVEYS, Issue 5 2001
Jesper Rangvid
Until the beginning of the 1990s, currency crises were typically analyzed within the framework of a generation of models that assumed that the foreign exchange reserves of a country that was running a fixed exchange rate policy were falling (because the government was running a deficit on its budget that was financed by printing money). When the foreign exchange reserves reached a lower bound, a speculative attack on the fixed exchange rate was launched. Today, this theory is no longer the benchmark when explaining the occurrence of a currency crisis. Actually, a new generation of models that seeks to take explicitly into account the costs and benefits associated with the maintenance of a fixed exchange rate has emerged. This paper surveys these ,second generation models of currency crises'. This generation of models emphasizes that it is an endogenous decision if a government chooses to abandon a policy of fixed exchange rates. The survey pays special attention to the fact that the second generation of currency crises models often generates multiple equilibria for the rate of devaluation given one state of the economic fundamentals. A currency crisis can thus occur even if no secular trend in economic fundamentals can be identified, as in recent currency crises. [source]

Secular trend in medical education regarding infectious disease

Bayesian longitudinal plateau model of adult grip strength

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2010
Ramzi W. Nahhas
Objectives: This article illustrates the use of applied Bayesian statistical methods in modeling the trajectory of adult grip strength and in evaluating potential risk factors that may influence that trajectory. Methods: The data consist of from 1 to 11 repeated grip strength measurements from each of 498 men and 533 women age 18,96 years in the Fels Longitudinal Study (Roche AF. 1992. Growth, maturation and body composition: the Fels longitudinal study 1929,1991. Cambridge: Cambridge University Press). In this analysis, the Bayesian framework was particularly useful for fitting a nonlinear mixed effects plateau model with two unknown change points and for the joint modeling of a time-varying covariate. Multiple imputation (MI) was used to handle missing values with posterior inferences appropriately adjusted to account for between-imputation variability. Results: On average, men and women attain peak grip strength at the same age (36 years), women begin to decline in grip strength sooner (age 50 years for women and 56 years for men), and men lose grip strength at a faster rate relative to their peak; there is an increasing secular trend in peak grip strength that is not attributable to concurrent secular trends in body size, and the grip strength trajectory varies with birth weight (men only), smoking (men only), alcohol consumption (men and women), and sports activity (women only). Conclusions: Longitudinal data analysis requires handling not only serial correlation but often also time-varying covariates, missing data, and unknown change points. Bayesian methods, combined with MI, are useful in handling these issues. Am. J. Hum. Biol. 22:648,656, 2010. © 2010 Wiley-Liss, Inc. [source]

Secular trend in age at menarche in indigenous and nonindigenous women in Chile

Persistence of growth stunting in a Peruvian high altitude community, 1964,1999

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2010
Ivan G. Pawson
The growth of children living in Nuñoa, a Peruvian high-altitude community, was studied over a 35-year period using data collected in 1964 and 1999. There had been evidence of a secular trend in growth in the mid-1980s, but this was before a period of sociopolitical upheaval lasting until the late 1990s partly linked to the activities of the Shining Path group and the Peruvian government's response. Anthropometric data for 576 children examined in 1964,1966 were compared with data from 361 children examined in 1999. Data were converted to Z Scores using NCHS/WHO reference standards. Compared with the 1964 cohort, boys in 1999 had marginally greater height Z Scores, but among females, the trend was reversed. Stunting prevalence had decreased from 1964 levels, but still approached 60% in both sexes, among the highest rates recorded for a modern world population. The prevalence of low weight for height was less than expected, possibly because of the compensatory effect of enlarged chest diameter. This anatomical feature may represent the effect of chronic hypoxic stress, causing growth of the chest cavity at the expense of growth in height. In view of modest improvements during the late 1980s in this population, we believe that the relatively poor growth status of children a decade later may result from food disruption associated with later political instability. Compared with children in a nearby community, which benefits from the socioeconomic infrastructure associated with a large copper mine, Nuñoa children continue to fare relatively poorly. Am. J. Hum. Biol. 2010. © 2009 Wiley-Liss, Inc. [source]

Age at menarche and the evidence for a positive secular trend in urban South Africa

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 1 2009
Laura L. Jones
Menarcheal age was estimated for 287 (188 Black; 99 White) urban South African girls born in Soweto-Johannesburg in 1990. The median menarcheal age for Blacks was 12.4 years (95% confidence interval (CI) 12.2, 12.6) and 12.5 years (95% CI 11.7, 13.3) for Whites. Data from six studies of menarcheal age, including the current study, were analyzed to examine the evidence for a secular trend between 1956 and 2004 in urban South African girls. There was evidence of a statistically significant secular trend for Blacks, but not Whites. Average menarcheal age for Blacks decreased from 14.9 years (95% CI 14.8, 15.0) in 1956 to 12.4 years (95% CI 12.2, 12.6) in the current study, an average decline of 0.50 years per decade. Fewer data were available for Whites, but average menarcheal age decreased from 13.1 years (95% CI 13.0, 13.2) in 1977 to 12.5 years (95% CI 11.7, 13.3) in the current study, an average decline of 0.22 years per decade. The diminishing age at menarche and the current lack of difference between Blacks and Whites is probably reflective of the continuing nutritional and socio-economic transition occurring within South Africa. Am. J. Hum. Biol., 2009. © 2008 Wiley-Liss, Inc. [source]

Postfamine stature and socioeconomic status in Ireland

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 6 2008
Kristin Young
Previous research has documented socioeconomic stratification of secular trend in height in historical populations. Using data from 4,900 males and 1,430 females born between 1840 and 1910 collected as part of the Harvard Anthropological Survey of Ireland (1934,1936), this study examined the secular changes in postfamine Ireland using several socioeconomic variables, including: occupation, migration, education, siblings, birthplace, and occupation of father and mother's father. Correlations were also calculated between height and various historical economic indices. Significant differences in the height of Irish males were found by occupation, education, and socioeconomic status of father and maternal grandfather. Males employed in agriculture, or whose fathers or grandfathers were so employed, were significantly taller than other males. For the smaller female sample, only occupation and grandfather's socioeconomic status had a significant impact on height. An inverse correlation was also found between the British Cost of Living Index (BCL) and male heights. Our results suggest that availability of resources plays an important role in the overall nutritional status reflected in terminal adult height. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source]

Secular changes in stature and body mass index for Chinese youth in sixteen major cities, 1950s,2005

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2008
Cheng-Ye Ji
Evidence shows a secular trend in physical growth in China in recent years. We analyze the secular trend of stature and body mass index (BMI) for the period 1950s,2005 to provide biological evidence for policy-makers to identify measures for improving Chinese children's health. Data come from the historical records in 1950s and the successive cycles of the Chinese National Survey on Student's Constitution and Health. Subjects were 7- to 18-year-old youth from 16 cities. Sex,age differences in mean stature and BMI values between the surveys were analyzed, and the increments per decade were compared. An overall positive secular trend was found in 1950s,2005. Mean stature of the 18-year olds increased from 166.6 to 173.4 cm for males and from 155.8 to 161.2 cm for females, yielding rates of 1.3 and 1.1 cm/decade; the overall increments of BMI values were 2.6 for males and 1.8 for females, yielding rates of 0.8 and 0.6/decade, respectively. The most significant changes occurred during puberty. The overall positive secular trend is closely associated with the socioeconomic progress and the improvement of livelihood. Strong evidence suggests that in China this trend will be continued for many years. Further studies are needed to explore how to ensure healthy changes for poorer rural youth. Effective preventive strategies and measures should be taken to prevent the progressive increase in the prevalence of childhood obesity accompanying this trend. Am. J. Hum. Biol., 2008. © 2008 Wiley-Liss, Inc. [source]

Paleodemography of a medieval population in Japan: Analysis of human skeletal remains from the Yuigahama-minami site

AMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2006
Tomohito Nagaoka
Abstract The purpose of this study is to obtain demographic data regarding the medieval population buried at the Yuigahama-minami site in Kamakura, Japan, and to detect a secular trend in the life expectancy of Japanese population over the last several thousand years. The Yuigahama-minami skeletal sample consists of 260 individuals, including 98 subadults (under 20 years old) and 162 adults. A Yuigahama-minami abridged life-table analysis yielded a life expectancy at birth (e0) of 24.0 years for both sexes, a life expectancy at age 15 years (e15) of 15.8 years for males, and an e15 of 18.0 years for females. The reliability of the estimated e0 was confirmed by analysis of the juvenility index. Demographic profiles comparing the Yuigahama-minami series with other skeletal series indicated that both the survivorship curve and life expectancy of the Yuigahama-minami sample are similar to those of the Mesolithic-Neolithic Jomon population, but are far lower than those of the early modern Edo population. These comparisons strongly suggest that life expectancy changed little over the thousands of years between the Mesolithic-Neolithic Jomon and medieval periods, but then improved remarkably during the few hundred years between the medieval period and early modern Edo period. The short-lived tendency of the Yuigahama-minami sample does not contradict the archaeological hypothesis of unsanitary living conditions in medieval Kamakura. This is the first investigation to address the demographic features of a medieval population in Japan, and will help refine our understanding of long-term trends in the demographic profiles of inhabitants of Japan. Am J Phys Anthropol, 2006. © 2006 Wiley-Liss, Inc. [source]

Age of puberty: Data from the United States of America,

APMIS, Issue 2 2001
Review article
In an attempt to determine whether the secular trend toward an earlier onset of puberty has continued over recent decades in the United States of America, published reports concerning the age of attainment of pubertal events have been reviewed. Such reports are very limited and vary in both design and inclusive ages of study subjects. Among females, two recent large cross-sectional studies indicate that fifty percent of females in the United States attain Tanner breast stage 2 at 9.5 to 9.7 years of age. This is younger than previously thought, although adequate earlier studies of girls in the United States are not available for comparison. These two studies also indicate that about 14% of girls attain Tanner stage 2 while 8 years of age; one study extends earlier reporting that about 6% exhibit onset of breast development while 7 years of age. There is no evidence that the age of menarche or the attainment of adult (Tanner 5) breast development has decreased over the past 30 years. The data also suggest an earlier onset of Tanner stage 2 pubic hair but no change in attainment of stage 5. Among males, pubic hair may be appearing at younger ages, but data are inadequate or too inconsistent to allow firm interpretation. The lack of standardization of genital criteria of pubertal onset in the male makes any conclusions regarding secular trends impossible. In summary, earlier secular trends over recent decades related to better health, improved nutrition or socio-economic status, or any putative influence by endocrine disrupters cannot be verified. [source]

The Big Bear Solar Observatory Ca II K-line index for solar cycle 23

ASTRONOMISCHE NACHRICHTEN, Issue 7 2010
M.F. Naqvi
Abstract We present an analysis of 2634 Ca II K-line full-disk filtergrams obtained with the 15-cm aperture photometric full-disk telescope at Big Bear Solar Observatory during the period from 1996 January 1 to 2005 October 24. Using limb darkening corrected and contrast enhanced filtergrams, solar activity indices were derived, which are sensitive to the 11-year solar activity cycle and 27-day rotational period of plages around active regions and the bright chromospheric network. The present work extends an earlier study (solar cycle 22), which was based on video data. The current digital data are of much improved quality with higher spatial resolution and a narrower passband ameliorating photometric accuracy. The time series of chromospheric activity indices cover most of solar cycle 23. One of the most conspicuous features of the Ca II K indices is the secondary maximum in late 2001/early 2002 after an initial decline of chromospheric activity during the first half of 2001. We conclude that a secular trend exists in the Ca II K indices, which has its origin in the bright chromospheric network and brightenings related to decaying active regions. Superposed on this secular trend are the signatures of recurring, long-lived active regions, which are clusters of persistent and continuously emerging magnetic flux. Such features are less visible, when the activity belts on both side of the equator are devoid of the brightenings related to decaying active regions as was the case in October/November 2003 at a time when a superactivity complex including several naked-eye sunspots emerged (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Breastfeeding Rates in Hong Kong: A Comparison of the 1987 and 1997 Birth Cohorts

BIRTH, Issue 3 2002
Gabriel M. Leung MD
ABSTRACT: Background: Low breastfeeding rates are an issue of international public health concern. Anecdotal reports suggest very low breastfeeding rates in Asia, but no population-based studies have been conducted in the region. To determine the secular trend in breastfeeding practice in an Asian postindustrialized metropolitan community, we examined data from two population-based birth cohorts of Hong Kong infants in 1987 and 1997. Methods: Annual population rates of breastfeeding initiation and duration were estimated from the birth cohorts, considering the change in breastfeeding rates over 10 years with correction for sociodemographic and birth characteristics. Factors associated with breastfeeding practice were identified using multivariate logistic regression modeling in a pooled analysis of individual data of both cohorts. Results: Overall, 26.8 percent of mothers initiated breastfeeding in 1987, and the rate increased to 33.5 percent in 1997. The rate would have been 27.4 percent in 1987 if the distributions of method of delivery, birthweight, birth order, maternal age, education, and employment status had been the same as in 1997. Only 7.6 percent of infants remained on the breast for more than 1 month in 1987 compared with 20.4 percent a decade later. Similarly, the rate for breastfeeding more than 3 months increased from 3.9 to 10.3 percent. Total breastfeeding duration was significantly longer in 1997 than 10 years earlier. Conclusions: This is the first systematic report of secular variations of breastfeeding rates in Asia. Hong Kong should set higher but realistic goals for breastfeeding that emphasize both initiation and maintenance. Given the wide latitude for improvement in terms of readily modifiable risk factors, such as smoking and cesarean section, these new goals should focus on improving rates in these targeted groups where breastfeeding rates are lowest. (BIRTH 29:3 September 2002) [source]