Long-term Secular Trends Research Articles

Long- and Short-Term Trends in Outpatient Attendance by Speciality in Japan: A Joinpoint Regression Analysis in the Context of the COVID-19 Pandemic

The COVID-19 pandemic resulted in a decline in outpatient attendance. Therefore, this study aimed to clarify long- and short-term clinic attendance trends by speciality in Japan between 2009 and 2021. A retrospective observational study of Japan’s claims between 2009 and 2021 was conducted using the Estimated Medical Expenses Database. The number of monthly outpatient claims in clinics was used as a proxy indicator for monthly outpatient attendance, and specialities were categorised into internal medicine, paediatrics, surgery, orthopaedics, dermatology, obstetrics and gynaecology, ophthalmology, otolaryngology, and dentistry. The annually summarised age-standardised proportions and the percentage of change were calculated. Joinpoint regression analysis was used to evaluate long-term secular trends. The data set included 4,975,464,894 outpatient claims. A long-term statistically significant decrease was observed in outpatient attendance in internal medicine, paediatrics, surgery, ophthalmology, and otolaryngology during the pandemic. From March 2020 to December 2021, which includes the COVID-19 pandemic period, outpatient attendance in paediatrics, surgery, and otolaryngology decreased in all months compared with that of the corresponding months in 2019. For some specialities, the impact of the pandemic was substantial, even in the context of long-term trends. Speciality-specific preparedness is required to ensure essential outpatient services in future public health emergencies.

Long-term secular trends in dermatomyositis and polymyositis mortality in the USA from 1981 to 2020 according to underlying and multiple cause of death mortality data

BackgroundPeople with dermatomyositis (DM) or polymyositis (PM) often die from cancer, pulmonary, cardiac complications, or infections. In such cases, DM or PM might not be designated as the underlying cause of death (UCD) for mortality tabulation. In this study, we investigated DM/PM mortality trends in the USA from 1981 to 2020 with respect to UCD and multiple causes of death (MCD) data.MethodsWe used the MCD data to identify all deaths with DM or PM mentioned anywhere on the death certificate and as the UCD in the USA from 1981–1982 to 2019–2020. We calculated age-adjusted mortality rates (AAMRs) and annual percentage changes (APCs) based on joinpoint regression analysis.ResultsWe identified 12,249 (3985 with DM and 7097 with PM) and 23,608 (8264 with DM and 15,344 with PM) people who died between 1981 and 2020 according to the UCD and MCD data, respectively. For DM, the APC was − 6.7% (from 1981–1982 to 1985–1986), − 0.1% (from 1985–1986 to 2003–2004), and − 1.9% (from 2003–2004 to 2019–2020) according UCD and was − 1.2% (from 1981–1982 to 2003–2004), − 2.5% (from 2003–2004 to 2015–2016), and 2.8% (from 2015–2016 to 2019–2020) according MCD. For PM, the APC was 1.9% (from 1981–1982 to 1989–1990), − 2.3% (from 1989–1990 to 2005–2006), and − 5.2% (from 2005–2006 to 2019–2020) according UCD and was 1.3% (from 1981–1982 to 1991–1992) and − 4.1% (from 1991–1992 to 2019–2020) according MCD.ConclusionWe identified two times as many DM/PM deaths using the MCD as those identified using the UCD. Similar downward DM/PM mortality trends were noted according to UCD and MCD. However, the year of significant decline in PM mortality was about 10 years earlier according to MCD than those according to UCD.

Incidence, Prevalence, and Mortality of Lupus Nephritis: A Population-Based Study Over Four Decades Using the Lupus Midwest Network.

There is a paucity of population-based studies investigating the epidemiology of lupus nephritis (LN) in the US and long-term secular trends of the disease and its outcomes. We aimed to examine the epidemiology of LN in a well-defined 8-county region in the US. Patients with incident LN between 1976 and 2018 in Olmsted County, Minnesota (1976-2009) and an 8-county region in southeast Minnesota (2010-2018) were identified. Age- and sex-specific incidence rates and point prevalence over 4 decades, adjusted to the projected 2000 US population, were determined. Standardized mortality ratios (SMRs), survival rates, and time to end-stage renal disease (ESRD) were estimated. There were 72 patients with incident LN between 1976 and 2018, of whom 76% were female and 69% were non-Hispanic White. Mean ± SD age at diagnosis was 38.4 ± 16.24 years. Average annual LN incidence per 100,000 population between 1976 and 2018 was 1.0 (95% CI 0.8-1.3) and was highest in patients ages 30-39 years. Between the 1976-1989 and 2000-2018 time periods, overall incidence of LN increased from 0.7 to 1.3 per 100,000, but this was not statistically significant. Estimated LN prevalence increased from 16.8 per 100,000 in 1985 to 21.2 per 100,000 in 2015. Patients with LN had an SMR of 6.33 (95% CI 3.81-9.89), with no improvement in the mortality gap in the last 4 decades. At 10 years, survival was 70%, and 13% of LN patients had ESRD. The incidence and prevalence of LN in this area increased in the last 4 decades. LN patients have poor outcomes, with high rates of ESRD and mortality rates 6 times that of the general population.

An ensemble learning strategy for panel time series forecasting of excess mortality during the COVID-19 pandemic

Quantifying and analyzing excess mortality in crises such as the ongoing COVID-19 pandemic is crucial for policymakers. Traditional measures fail to take into account differences in the level, long-term secular trends, and seasonal patterns in all-cause mortality across countries and regions. This paper develops and empirically investigates the forecasting performance of a novel, flexible and dynamic ensemble learning with a model selection strategy (DELMS) for the seasonal time series forecasting of monthly respiratory disease death data across a pool of 61 heterogeneous countries. The strategy is based on a Bayesian model averaging (BMA) of heterogeneous time series methods involving both the selection of the subset of best forecasters (model confidence set), the identification of the best holdout period for each contributed model, and the determination of optimal weights using out-of-sample predictive accuracy. A model selection strategy is also developed to remove the outlier models and to combine the models with reasonable accuracy in the ensemble. The empirical outcomes of this large set of experiments show that the accuracy of the BMA approach is significantly improved with DELMS when selecting a flexible and dynamic holdout period and removing the outlier models. Additionally, the forecasts of respiratory disease deaths for each country are highly accurate and exhibit a high correlation (94%) with COVID-19 deaths in 2020.

Volatility, Realignment and Electoral Shocks: Brexit and the UK General Election of 2019

There has been some debate as to whether the 2019 General Election was a Brexit election – even a critical election – or the continuation of long-term realignments in British Politics. In this article we argue that, while the process of realignment has its roots long-before the referendum of 2016, to properly understand the 2019 election we must recognise the interplay of long-term secular trends and the electoral shock of Brexit. We demonstrate how Brexit continued to structure electoral choices in 2019 as manifested in a crystallization of shifting electoral cleavages around social class, geography, education and age; the persistence of alternative political identities; and a reversal in electoral volatility. While these developments are consistent with the early stages of a realignment catalysed by the EU referendum in 2016, it is still too early to determine whether they should be considered a long-term critical realignment, or a temporary but very substantial interruption to politics as usual.

Oral cancer incidence rates from 1997 to 2016 among men in Taiwan: Association between birth cohort trends and betel nut consumption.

Oral cancer is the fourth most common cancer among men in Taiwan. Betel nut consumption is a major risk factor for oral cancer, but the association between betel nut chewing and the long-term secular trend of oral cancer incidence is unclear. We conducted an age-period-cohort analysis to examine the incidence rates of oral cancer among men in Taiwan from 1997 to 2016. The oral cancer incidence rate among men doubled between 1997 and 2009, but the trend leveled off thereafter. Oral cancer incidence rates in the oldest age group (80-84y) were approximately 85 times those of the youngest group (25-29y). The period effect was weak, and the cohort effect exhibited a drastically increasing trend from 1917 (midyear for 1913-1921) to 1972 (1968-1976) birth cohorts and then a decreasing trend afterward. The Spearman rank correlation coefficient between the cohort effects on oral cancer incidence among men and the average consumption of betel nut with a lag time of 30years had a significant and extremely high value of 0.993. Our findings suggest that betel nut chewing is the main driver of the cohort effect for oral cancer incidence rates among men in Taiwan. In addition to reduced betel nut consumption, a decrease in smoking prevalence may also have contributed to the reduction in oral cancer incidence after the 1972 birth cohort; moreover, the increasing prevalence of alcohol consumption in Taiwan is unlikely to be the reason for the cohort effect for oral cancer.

Association of Utilization Management Policy With Uptake of Hypofractionated Radiotherapy Among Patients With Early-Stage Breast Cancer

Breast cancer accounts for the largest portion of cancer-related spending in the United States. Although hypofractionated radiotherapy after breast-conserving surgery is a cost-effective and convenient treatment strategy for patients with early-stage breast cancer, less than 40% of eligible women received hypofractionated radiotherapy in 2013. To assess the association of a large commercial payer's utilization management policy with the use of hypofractionated radiotherapy among women with early-stage breast cancer and its associated cost. A retrospective, adjusted difference-in-differences economic analysis was conducted using administrative claims data from January 1, 2012, to June 1, 2018, of women 18 years or older with early-stage breast cancer who were eligible for hypofractionated radiotherapy according to 2011 guidelines from the American Society for Radiation Oncology and were continuously enrolled in 14 geographically diverse commercial health plans covering 6.9% of US adult women. Women who received mastectomy, brachytherapy, or less than 11 or more than 40 external beam fractions of radiotherapy were excluded. A utilization management policy was used to encourage the use of hypofractionated radiotherapy among women in fully insured and Medicare Advantage (fully insured) plans. Under the new policy, claims for extended-course radiotherapy were not reimbursed for fully insured women who were eligible for hypofractionated radiotherapy. This policy did not apply to women in self-insured or Medicare supplemental insurance (self-insured) plans, allowing these groups to serve as a comparison group. The primary outcome was use of hypofractionated radiotherapy, and the secondary outcome was the cost of this type of radiotherapy. Of 10 540 eligible women, 3619 (34.3%) were in fully insured plans and thus subject to the policy. There were no meaningful differences between the fully insured and self-insured groups in mean (SD) age at the start of radiotherapy (63.8 [8.6] vs 65.0 [8.9] years), mean (SD) Charlson Comorbidity Index score (3.0 [1.5] vs 3.2 [1.6]), or practice setting (outpatient hospital setting, 2982 of 3619 [82.4%] vs 5600 of 6921 [80.9%]). The policy was associated with an increase in use of hypofractionated radiotherapy among fully insured patients subject to the policy (adjusted percentage point difference-in-difference, 4.2%; 95% CI, 0.0%-8.4%; P = .05) and a nonsignificant decrease in radiotherapy-associated expenditures (-$2275 relative to self-insured patients; P = .09). Spillover analyses revealed a significantly higher uptake of hypofractionated radiotherapy among self-insured patients who were indirectly exposed to the policy (adjusted percentage point difference-in-difference, 8.5%; 95% CI, 3.6%-13.5%; P < .001) compared with those who were not exposed. This study suggests that a payer's utilization management policy was associated with direct and spillover increases in the use of hypofractionated radiotherapy, even after accounting for a long-term secular trend in the uptake of hypofractionated radiotherapy in the control groups. Utilization management may promote evidence-based cancer care.

Secular Trends of Hip Fractures in Lebanon, 2006 to 2017: Implications for Clinical Practice and Public Health Policy in the Middle East Region.

Country-specific hip fracture incidence rates (IRs) and longevity allow the Fracture Risk Assessment Tool (FRAX) to be adapted to individual countries. Secular trends can affect tool calibration. Data on hip fracture IRs in the Middle East is scarce, and long-term secular trend studies are nonexistent. Using the Ministry of Public Health hip fracture registry, we calculated age- and sex-specific hip fracture IRs in Lebanon, from 2006 to 2017, among individuals aged ≥50 years. We used Kendall's tau-b (τb) test to determine the correlation between time and hip fracture IRs, and calculated both the annual % change in IRs and the % change in IR compared to the baseline period (2006 to 2008). The registry recorded 6985 hip fractures, 74% at the femoral neck, 23% intertrochanteric, and 3% subtrochanteric. Men constituted 32% of the population, and were significantly younger than women (76.5 ± 11.0 years versus 77.7 ± 10.3 years; p < 0.001). Annual overall IRs, per 100,000, ranged from 126.6 in 2014 to 213.2 in 2017 in women, and 61.4 in 2015 to 111.7 in 2017 in men. The average women to men IR ratio was 1.8 (range, 1.5 to 2.1). IRs steadily increased with age, and IR ratios increased in parallel in both sexes, with a steeper and earlier rise (by 5 years) in women. Data showed a consistent decline in hip fracture IRs starting in 2006 in women, and in 2009 in men. There was a significant negative correlation between time (2006 to 2014) and hip fracture IRs in women (τb = -0.611, p = 0.022) but not in men (τb = -0.444, p = 0.095). The steady decrease in IRs reversed after 2015 in both sexes. This long-term data on secular trends in the Middle East is novel and consistent with worldwide changes in hip fracture rates. The impact of such changes on national FRAX-derived estimates is unclear, should be assessed, and may necessitate an update in the FRAX Lebanon calculator. © 2019 American Society for Bone and Mineral Research.

Visual Acuity Improves in Children and Adolescents With Idiopathic Infantile Nystagmus.

Idiopathic infantile nystagmus is associated with reduced visual acuity. Recent work has linked extraocular muscle surgery to improvements in visual acuity through childhood but no work has reported long-term secular trends in visual acuity in infantile nystagmus. Our aim is to describe visual acuity changes for children and adolescents with idiopathic infantile nystagmus to allow comparison for future interventional studies. Retrospective chart review. Review of patients attending our center up to the age of 18 with a diagnosis of idiopathic infantile nystagmus and visual acuity measured using Snellen visual acuity. Patients provided informed consent. We observed improvements in best corrected visual acuity in 43 children and adolescents with idiopathic infantile nystagmus. Binocular best corrected visual acuity improved at a rate of -0.16 logarithm of the minimum angle of resolution (logMAR)/log year of age (P < 0.001), an improvement of 0.05 logMAR (half a Snellen line) as the age doubles. Intraclass correlation was 0.95 and interindividual correlation between visual acuity and age was significant (r = -0.24, P < 0.001). We describe a natural history of gradual improvement in binocular visual acuity in infantile nystagmus and provide a baseline against which future interventional work can be compared.

Rotavirus vaccination takes seasonal signature of childhood diarrhea back to pre-sanitation era in Brazil

This study aimed to examine the previously unknown long-term spatio-temporal patterns in diarrheal morbidity and mortality across age groups and geography in Brazil under the light of evolving socioeconomic factors and interventions. Nationwide mortality (1979-2014) and hospitalization (1998-2014) data were obtained from the Brazilian Ministry of Health. Analyses of long-term secular trends and seasonality of diarrheal morbidity and mortality were performed in EPIPOI (www.epipoi.info). For most states, the primary peak in mortality risk among children under 5 years occurred from December-April (summer/early autumn) from 1979-1988. From 2000-2005 (before the 2006 implementation of rotavirus vaccination), the pattern switched to June-October (winter/early spring). By 2007-2014, the peak in mortality shifted back towards summer/early autumn. A similar pattern was observed for hospitalizations. These patterns were particularly apparent in non-equatorial regions of the country. In contrast, the risk of diarrhea-related death among older children (5-19 years) did not demonstrate well-defined seasonality or spatial patterns. Rotavirus vaccination policies were associated with a shift in the timing of seasonal peaks in children under 5, reminiscent of the summer diarrhea period common decades prior. Additionally, young children were shown to have distinct disease patterns compared to other age groups, suggesting different etiologies.

Experiments based on blue intensity for reconstructing North Pacific temperatures along the Gulf of Alaska

Abstract. Ring-width (RW) records from the Gulf of Alaska (GOA) have yielded a valuable long-term perspective for North Pacific changes on decadal to longer timescales in prior studies but contain a broad winter to late summer seasonal climate response. Similar to the highly climate-sensitive maximum latewood density (MXD) proxy, the blue intensity (BI) parameter has recently been shown to correlate well with year-to-year warm-season temperatures for a number of sites at northern latitudes. Since BI records are much less labour intensive and expensive to generate than MXD, such data hold great potential value for future tree-ring studies in the GOA and other regions in mid- to high latitudes. Here we explore the potential for improving tree-ring-based reconstructions using combinations of RW- and BI-related parameters (latewood BI and delta BI) from an experimental subset of samples at eight mountain hemlock (Tsuga mertensiana) sites along the GOA. This is the first study for the hemlock genus using BI data. We find that using either inverted latewood BI (LWBinv) or delta BI (DB) can improve the amount of explained temperature variance by &gt; 10 % compared to RW alone, although the optimal target season shrinks to June–September, which may have implications for studying ocean–atmosphere variability in the region. One challenge in building these BI records is that resin extraction did not remove colour differences between the heartwood and sapwood; thus, long term trend biases, expressed as relatively warm temperatures in the 18th century, were noted when using the LWBinv data. Using DB appeared to overcome these trend biases, resulting in a reconstruction expressing 18th–19th century temperatures ca. 0.5 °C cooler than the 20th–21st centuries. This cool period agrees well with previous dendroclimatic studies and the glacial advance record in the region. Continuing BI measurement in the GOA region must focus on sampling and measuring more trees per site (&gt; 20) and compiling more sites to overcome site-specific factors affecting climate response and using subfossil material to extend the record. Although LWBinv captures the inter-annual climate signal more strongly than DB, DB appears to better capture long-term secular trends that agree with other proxy archives in the region. Great care is needed, however, when implementing different detrending options and more experimentation is necessary to assess the utility of DB for different conifer species around the Northern Hemisphere.

Secular change and inter-annual variability of the Gulf Stream position, 1993–2013, 70°−55°W

The Gulf Stream (GS) is the northeastward-flowing surface limb of the Atlantic Ocean's meridional overturning circulation (AMOC) “conveyer belt” that flows towards Europe and the Nordic Seas. Changes in the GS position after its separation from the coast at Cape Hatteras, i.e., from 75°W to 50°W, may be key to understanding the AMOC, sea level variability and ecosystem behavior along the east coast of North America. In this study we compare secular change and inter-annual variability (IAV) of the Gulf Stream North Wall (GSNW) position with equator-ward Labrador Current (LC) transport along the southwestern Grand Banks near 52°W using 21 years (1993–2013) of satellite altimeter data. Results at 55°, 60°, and 65°W show a significant southward (negative) secular trend for the GSNW, decreasing to a small but insignificant southward trend at 70°W. IAV of de-trended GSNW position residuals also decreases to the west. The long-term secular trend of annual mean upper layer (200m) LC transport near 52°W is positive. Furthermore, IAV of LC transport residuals near 52°W along the southwestern Grand Banks are significantly correlated with GSNW position residuals at 55°W at a lag of +1-year, with positive (negative) LC transport residuals corresponding to southward (northward) GSNW positions one year later. The Taylor-Stephens index (TSI) computed from the first principal component of the GSNW position from 79° to 65°W shows a similar relationship with a more distal LC index computed along altimeter ground track 250 located north of the Grand Banks across Hamilton Bank in the western Labrador Sea. Increased (decreased) sea height differences along ground track 250 are significantly correlated with a more southward (northward) TSI two years later (lag of +2-years). Spectral analysis of IAV reveals corresponding spectral peaks at 5–7 years and 2–3 years for the North Atlantic Oscillation (NAO), GSNW (70°−55°W) and LC transport near 52°W for the 1993–2013 period suggesting a connection between these phenomena. An upper-layer (200m) slope water volume calculation using the LC IAV rms residual of +1.04Sv near 52°W results in an estimated GSNW IAV residual of 79km, or 63% of the observed 125.6km (1.13°) rms value at 55°W. A similar upper-layer slope water volume calculation using the positive long-term, upper-layer LC transport trend accounts for 68% of the mean observed secular southward shift of the GSNW between 55° and 70°W over the 1993–2013 period. Our work provides additional observational evidence of important interactions between the upper layers of the sub-polar and sub-tropical gyres within the North Atlantic over both secular and inter-annual time scales as suggested by previous studies.

Declining inequality in Latin America: structural shift or temporary phenomenon?

Latin America has been traditionally characterized as a region with high levels of income inequality. Since the early 2000s, however, inequality has started to decline in most countries, basically due to an expansion of the income share of the poorest deciles at the expense of the richest 10%. This paper addresses the question of whether the improvements are driven by long-term secular trends or structural changes which could be expected to continue to generate inequality-reducing effects for years to come; or alternatively, if the changes are driven by short-term variables which could move unexpectedly in the opposite direction and reverse the gains observed so far. From our statistical analysis, we conclude that the improvements are associated with both long- and short-term factors – with the short-term factors recently having greater inequality-reducing changes.

Trends in the epidemiology of osteomyelitis: a population-based study, 1969 to 2009.

The epidemiology of osteomyelitis in the United States is largely unknown. The purpose of this study was to determine long-term secular trends in the incidence of osteomyelitis in a population-based setting. The study population comprised 760 incident cases of osteomyelitis first diagnosed between January 1, 1969, and December 31, 2009, among residents of Olmsted County, Minnesota. The complete medical records for each potential subject were reviewed to confirm the osteomyelitis diagnosis and to extract details on anatomical sites, infecting organisms, etiological risk factors, and outcomes. The overall age and sex-adjusted annual incidence of osteomyelitis was 21.8 cases per 100,000 person-years. The annual incidence was higher for men than for women and increased with age (p < 0.001). Rates increased with the calendar year (p < 0.001) from 11.4 cases per 100,000 person-years in the period from 1969 to 1979 to 24.4 per 100,000 person-years in the period from 2000 to 2009. The incidence remained relatively stable among children and young adults but almost tripled among individuals older than sixty years; this was partly driven by a significant increase in diabetes-related osteomyelitis from 2.3 cases per 100,000 person-years in the period from 1969 to 1979 to 7.6 cases per 100,000 person-years in the period from 2000 to 2009 (p < 0.001). Forty-four percent of cases involved Staphylococcus aureus infections. The reasons for the increase in osteomyelitis between 1969 and 2009 are unclear but could comprise a variety of factors, including changes in diagnosing patterns or increases in the prevalence of risk factors (e.g., diabetes) in this population.

Secular trends in end-stage renal disease requiring dialysis inManitoba, Canada: a population-based study.

End-stage renal disease (ESRD) requiring dialysis is expensive and is associated with disproportionately poor health outcomes and quality of life. Understanding regional long-term secular trends in the incidence and prevalence of dialysis will allow for the alignment of appropriate and efficient delivery of care. The primary objective of this study was to describe long-term secular and geographic trends in ESRD over a 22-year period in a single-provider Canadian health care setting. Using a previously validated case definition, we described the annual incidence and prevalence of ESRD in Manitoba from 1989 to 2010, stratified by age, sex and geographic location within the province. We searched more than 1.2million records within the Manitoba Health repository. We identified 9489patients in the Manitoba Health Physician Claims database with at least 1 claim for dialysis from 1989 through Mar. 31, 2010. Using the case definition of any 2dialysis treatment claims, the total annual incidence of ESRD increased 2.5-fold from 15.8 to 40.2 per 100000 during the study period. Of note, the northern rural portions of the province saw a 12-fold unadjusted increase in ESRD, from 8.1 per 100 000 in 1989 to 96.3 per 100000 in 2009. The incidence and prevalence of ESRD is increasing in Manitoba, most notably in the north of the province. Innovative interventions, such as primary screening and treatment initiatives, should specially target northern rural regions.

Correspondence: The Profitability of Primacy

Correspondence: The Profitability of Primacy

Long-Term Secular Trends in the Age at Menarche in Israel: A Systematic Literature Review and Pooled Analysis

Background/Aims: A worldwide decline in the age at menarche (AAM) has been reported in recent decades. This trend has been also clinically observed among Israeli women and was reported in our previous study. Methods: We reviewed the literature reporting the mean AAM in Israel during the past century. Studies were excluded if participants had been investigated due to illness or any condition which could affect sexual maturation. Mean AAM was analyzed using a simple linear regression weighted for number of participants in each birth cohort and stratified to birth cohorts before and after 1970, based on the outcome of our previous study. Results: AAM varied little among women born between 1875 and 1970, but there was a clear downwards trend from 13.4 in 1970 to 12.8 two decades later. In a stratified analysis we found a significant negative association between birth year and AAM in the birth cohort after 1970 (standardized β coefficient = -0.94 per year, R² = 0.87; p < 0.001). Conclusion: These results suggest a significant decline in mean AAM in Israeli women born in 1970 or later.

Long-term secular trend of skeletal maturation of Taiwanese children between agricultural (1960s) and contemporary (after 2000s) generations using the Tanner-Whitehouse 3 (TW3) method

The Tanner-Whitehouse (TW) method is one of the well-known techniques in determining the bone age. According to the objectivity of TW3, the secular trend was investigated to discover whether the skeletal maturation of Taiwanese children between two generations was different. The large-scale database of Taiwan was collected. The first group, called mid-1960s, included 265 boys and 295 girls in the agricultural generation (between 1966 and 1967). The second group, called mid-2000s, includes 114 boys and 616 girls in the contemporary generation (after 2000s). The bone age was determined by three radiologists using the carpals-only system of the TW3 method and by two physicians using the Greulich and Pyle method. A comparison of the means (independent-samples t-test) was applied by examining the difference of the children's skeletal maturation between the two generations in the same chronological age. The significant difference was considered while the p-value was 0.05 or less (95% confidence interval). A significant difference of the mean bone age (by, on average, three radiologists using the TW3 method) between the mid-1960s and mid-2000s in the same gender and chronological age was presented by the independent-samples t-test (p<0.001 with 95% confidence interval), and the bone age, determined by the TW3 method, of the mid-2000s group was higher than that of the mid-1960s group. This scenario corresponded with the children's bone age determined by pediatricians. Besides, it deserved to notice that the bone age of boys in the mid-2000s was larger than that of the girls in the mid-1960s. Furthermore, by comparing the environmental condition, we suspect that the difference of bone age of children between the two generations was attributed to the discrepancy in nutrition and socioeconomic variation during the four decades in Taiwan. The study presents that the secular trend of skeletal maturation of children in the mid-2000s is faster than that in the mid-1960s.

Interdecadal oscillations in Atmospheric Angular Momentum variations

Interdecadal oscillations in Atmospheric Angular Momentum variationsGlobal Atmospheric Angular Momentum (AAM) is an intrinsic index for describing processes that affect the atmospheric circulation on time scales ranging from intraseasonal to secular. It is associated with length-of-day (LOD) variability through conservation of global angular momentum in planet Earth and thus is of considerable importance for quantifying how the Earth acts as a system. The availability of lengthy AAM time series computed from the recent 20th Century atmospheric reanalyses (1870-2008), complemented by the NCAR-NCEP reanalysis in the overlapping period of 1948-2008 allows the investigation of the role of decadal and interdecadal cycles as well as the recent overall trend in AAM. Thus, we extend to the entire 20th century (and prior, back to 1870) results concerning decadal time scales and a secular positive trend detected over recent decades by different authors. In addition, we also note that AAM has features of interdecadal time scales that modulate the lower frequency variability. These interdecadal time signals oscillate with periods of about 30-50 years, and we found an indication of an 80-90 year period. Short term signals interact with the long-term (secular) trend. Particularly over the years 1950-1985 the global positive trend in AAM appears to result from a conjunction of constructive positive slopes from all lower frequency signals (interdecadal short-term trends and the long-term positive secular trend). Since the mid 1980s, however, the interdecadal oscillation short-term trend contribution decreases, as does the total signal in global AAM. These oscillations appear as two interdecadal modes originating within the Pacific (associated principally with the Pacific Decadal Oscillation and also ENSO) from which they propagate poleward, with differing characteristics in each hemisphere.

Long-term trends in the temperature of the mesosphere/lower thermosphere region: 1. Anthropogenic influences

[1] A detailed overview of long-term secular trends in temperature of the mesosphere and lower thermosphere considered to be induced by increase in greenhouse gases has been provided by Beig et al. (2003). Since then, quite a few new results have been emerged as some of the data series have become sufficiently large enough to provide results with improved confidence. Our understanding on the nature of temperature trends in the mesosphere/lower thermosphere (MLT) region is relatively better now. In the mesosphere, some of the results confirmed the earlier findings, and some new results obtained by satellite and lidar data over the tropical region have indicated a relatively weaker cooling trend as compared to the past but nevertheless strengthened the conclusion about the cooling trends. However, in the mesopause region, some of the new results now indicate a break in trend and tendency of negative signal where earlier no trend feature was noticed. This slice of no trend feature in between two cooling regimes was puzzling the modeling community, who were in search of a convincing explanation. This paper briefly outlines the progress made over the recent past in the field of MLT region secular temperature trends attributed mainly to growth of greenhouse gases near the Earth's surface.