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Medical Sciences	75%

Selected Abstracts

Consistency of modelled and observed temperature trends in the tropical troposphere

INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 13 2008
B. D. Santer
Abstract A recent report of the U.S. Climate Change Science Program (CCSP) identified a ,potentially serious inconsistency' between modelled and observed trends in tropical lapse rates (Karl et al., 2006). Early versions of satellite and radiosonde datasets suggested that the tropical surface had warmed more than the troposphere, while climate models consistently showed tropospheric amplification of surface warming in response to human-caused increases in well-mixed greenhouse gases (GHGs). We revisit such comparisons here using new observational estimates of surface and tropospheric temperature changes. We find that there is no longer a serious discrepancy between modelled and observed trends in tropical lapse rates. This emerging reconciliation of models and observations has two primary explanations. First, because of changes in the treatment of buoy and satellite information, new surface temperature datasets yield slightly reduced tropical warming relative to earlier versions. Second, recently developed satellite and radiosonde datasets show larger warming of the tropical lower troposphere. In the case of a new satellite dataset from Remote Sensing Systems (RSS), enhanced warming is due to an improved procedure of adjusting for inter-satellite biases. When the RSS-derived tropospheric temperature trend is compared with four different observed estimates of surface temperature change, the surface warming is invariably amplified in the tropical troposphere, consistent with model results. Even if we use data from a second satellite dataset with smaller tropospheric warming than in RSS, observed tropical lapse rate trends are not significantly different from those in all other model simulations. Our results contradict a recent claim that all simulated temperature trends in the tropical troposphere and in tropical lapse rates are inconsistent with observations. This claim was based on use of older radiosonde and satellite datasets, and on two methodological errors: the neglect of observational trend uncertainties introduced by interannual climate variability, and application of an inappropriate statistical ,consistency test'. Copyright © 2008 Royal Meteorological Society [source]

Effects of Maternal Characteristics on Cesarean Delivery Rates among U.S. Department of Defense Healthcare Beneficiaries, 1996,2002

BIRTH, Issue 1 2004
Andrea Linton MS
Nonclinical factors associated with cesarean delivery include maternal age, race, socioeconomic status, and insurance coverage. This study compared cesarean delivery rates and trends for the U.S. Department of Defense healthcare beneficiary population from 1996 to 2002 with those observed nationally, and assessed the association of these nonclinical factors with cesarean rate variation in the U.S. Department of Defense healthcare beneficiary population. Methods: Hospital discharge and claims records for babies born in the military and civilian hospitals that comprise the Department of Defense healthcare network were used to calculate total and primary cesarean delivery rates and vaginal birth after cesarean (VBAC) rates from 1996 to 2002. Annual cesarean rates for subgroups defined by maternal age, race, and socioeconomic status were calculated to examine rate variations and rate trends within the study population. Pooled data from 1999 to 2002 were used to compare rates across socioeconomic status, stratified by age and race. Statistical significance of the differences calculated for subgroups was assessed using chi-square. Results: Total and primary cesarean delivery rates among the U.S. Department of Defense population were lower than those reported nationally for every year examined. Cesarean delivery and VBAC rate trends in the national and Department of Defense populations were similar. Within the Department of Defense population, total cesarean delivery increased with increasing maternal age and was more highly associated with racial minorities relative to white women. The higher socioeconomic subgroup (defined as active duty, retired, and warrant officers and their families in this study) was generally associated with reduced cesarean delivery rates. Conclusions: Cesarean deliveries are performed less frequently for the U.S. Department of Defense healthcare beneficiary population relative to the national population. Associations between socioeconomic factors and cesarean rates reported for the national population were not apparent in the study population. The consistent pattern of rate variation across racial subgroups in the Department of Defense population suggests that factors beyond those examined in this study are needed to explain the elevated cesarean rates for racial minorities. (BIRTH 31:1 March 2004) [source]

Trends in palatine tonsillar cancer incidence and mortality rates in the United States

COMMUNITY DENTISTRY AND ORAL EPIDEMIOLOGY, Issue 2 2007
Sylvia M. Golas
Abstract,,, Objective:, The purpose of this paper is to describe the extent of the public health problem presented by palatine tonsillar cancer in the United States by analyzing recent incidence and mortality rate trends. Methods:, Using the National Cancer Institutes' Surveillance, Epidemiology and End Results (SEER) Program database, age-adjusted incidence rates (1973,2001) for five histological types of palatine tonsillar cancer by race and sex were calculated. For total palatine tonsillar cancer age-specific incidence (1973,2001) and mortality (1969,2001) rates by race and sex were calculated. Mortality and population data were obtained from the National Center for Health Statistics (NCHS) and the U.S. Census Bureau. The Joinpoint Regression Model was employed to establish the statistical significance of incidence and mortality rate trends. Results:, The majority of palatine tonsillar cases diagnosed in SEER-9 registries from 1973 to 2001 occurred among white males, age 40,64 years, with squamous cell carcinoma (SCC). The highest incidence of palatine tonsillar cancer occurred in black males, followed by white males with SCC. For age 40,64 years, palatine tonsillar incidence rates significantly declined for white females and black females, rose and then declined for black males, but increased from 1988 for white males. For age 65+ years, incidence significantly declined among white males. Palatine tonsillar cancer mortality rates for age 40,64 years significantly declined for white females. Rates also declined for black females (1981,2001) and black males (1985,2001) in this age group while rates for white males declined significantly from 1969 to 1987, but stabilized at nearly 0.4 through 2001. Mortality for the age group, 65+, significantly rose and fell for white females and declined for white males. Conclusions:, Beginning in the late 1980s, and continuing through 2001, the risk for white males, age 40,64 years, of developing palatine tonsillar cancer increased. In contrast, the risk for white males, age 65 years and older, of developing palatine tonsillar cancer and of dying from this disease decreased during the study period. [source]