97 research outputs found
Effect of time to diagnostic testing for breast, cervical, and colorectal cancer screening abnormalities on screening efficacy: A modeling study
Background: Patients who receive an abnormal cancer screening result require follow-up for diagnostic testing, but the time to follow-up varies across patients and practices. Methods: We used a simulation study to estimate the change in lifetime screening benefits when time to follow-up for breast, cervical, and colorectal cancers was increased. Estimates were based on four independently developed microsimulation models that each simulated the life course of adults eligible for breast (women ages 50–74 years), cervical (women ages 21–65 years), or colorectal (adults ages 50–75 years) cancer screening. We assumed screening based on biennial mammography for breast cancer, triennial Papanicolaou testing for cervical cancer, and annual fecal immunochemical testing for colorectal cancer. For each cancer type, we simulated diagnostic testing immediately and at 3, 6, and 12 months after an abnormal screening exam. Results: We found declines in screening benefit with longer times to diagnostic testing, particularly for breast cancer screening. Compared to immediate diagnostic testing, testing at 3 months resulted in reduced screening benefit, with fewer undiscounted life years gained per 1,000 screened (breast: 17.3%, cervical: 0.8%, colorectal: 2.0% and 2.7%, from two colorectal cancer models), fewer cancers prevented (cervical: 1.4% fewer, colorectal: 0.5% and 1.7% fewer, respectively), and, for breast and colorectal cancer, a less favorable stage distribution. Conclusions: Longer times to diagnostic testing after an abnormal screening test can decrease screening effectiveness, but the impact varies substantially by cancer type. Impact: Understanding the impact of time to diagnostic testing on screening effectiveness can help inform quality improvement efforts. Cancer Epidemiol Biomarkers Prev; 27(2); 158–64. 2017 AACR
Non-bee insects are important contributors to global crop pollination
Wild andmanaged bees arewell documented as effective pollinators of global crops of economic importance. However, the contributions by pollinators other than bees have been little explored despite their potential to contribute to crop production and stability in the face of environmental change. Non-bee pollinators include flies, beetles, moths, butterflies, wasps, ants, birds, and bats, among others. Here we focus on non-bee insects and synthesize 39 field studies from five continents that directly measured the crop pollination services provided by non-bees, honey bees, and other bees to compare the relative contributions of these taxa. Non-bees performed 25-50% of the total number of flower visits. Although non-bees were less effective pollinators than bees per flower visit, they made more visits; thus these two factors compensated for each other, resulting in pollination services rendered by non-bees that were similar to those provided by bees. In the subset of studies that measured fruit set, fruit set increased with non-bee insect visits independently of bee visitation rates, indicating that non-bee insects provide a unique benefit that is not provided by bees. We also show that non-bee insects are not as reliant as bees on the presence of remnant natural or seminatural habitat in the surrounding landscape. These results strongly suggest that non-bee insect pollinators play a significant role in global crop production and respond differently than bees to landscape structure, probably making their crop pollination services more robust to changes in land use. Non-bee insects provide a valuable service and provide potential insurance against bee population declines.Peer Reviewe
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Fundamental studies of stress distributions and stress relaxation in oxide scales on high temperature alloys
The high temperature X-ray diffraction system developed for this program is being used to measure the strains which develop during oxidation. This is being applied to Ni/NiO and Cr/Cr[sub 2]O[sub 3]. Our work suggests tat the oxide and metal crystalline texture, anisotropic elastic modulus and anisotropic thermal expansion can have a pronounced effect on strain state of these systems. Acoustic emission is being used to study oxide scale failure (fracture) during oxidation. AE data from 304 stainless steel are being used to develop a statistical model of fracture process. Strength of metal/scale interface is an important property that has been difficult to quantify. Using Nano-indentation and scratch techniques developed for characterizing thin film interfaces, an effort has begun to measure the fracture toughness of the metal/scale interface. Mathematical modelling of origin and time evolution of growth stresses is an extension and improvement of previous models. The current effort employs a more sophisticated stress analysis and expands the scope to include other stress relaxation process. The interaction between the modeling studies and the X-ray diffraction measurements provides a natural credibility check to both efforts
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A study of scale cracking and its effects on oxidation and hot corrosion
For many high temperature applications, oxidation (or hot corrosion) is an important mode of degradation of metals and alloys. Degradation mechanisms may be divided into two categories: one dealing with the chemical and transport aspects of scale growth or dissolution, and the other dealing with mechanical aspects such as stresses and scale fracture. Some applications, such as corrosion/erosion, combine both aspects in a complicated manner. Much research has been concerned with relationships between alloy composition and scale growth rates, attempting to identify alloy compositions and growth mechanisms that form compact, slow-growing scales, such as Cr{sub 2}O{sub 3} or Al{sub 2}O{sub 3}. Nevertheless, in practice a very common mode of scale degradation is cracking and spalling, followed by re-oxidation. Efforts to understand scale stresses and ultimately scale fracture have been hampered by the simultaneous interaction of numerous variables in determining the state of stress. Thus complex issues are involved in both experimental measurements and theoretical models of stresses and fracture of oxide scales. In this study we have considered both chemical/transport issues (as applied to the oxidation and hot corrosion of SiC and Ni-Cr Alloys) and mechanical issues of oxidation, but the emphasis has been on mechanical issues. In the following sections we will briefly describe the highlights of each of several projects, and where appropriate, will attach preprints or reprints of papers that describe in more detail the results of a particular study
Ultrasonographic measurements of localized fat accumulation in Shetland pony mares fed a normal v. a high energy diet for 2 years
Health risks associated with obesity are more likely a factor of the localization of fat excess, rather than of elevated BW per se. The aim of this randomized controlled clinical trial was to determine the effect of a long-term high energy diet on BW, fat accumulation and localization. Eight Shetland pony mares, 3 to 7 years old, were randomly divided into a control and a high energy (HE) diet group fed either maintenance or double maintenance energy requirements (200% net energy (NE)) for two consecutive summers, with a low energy diet in the winter in between. Body condition score (BCS) did not differ between the groups at the onset of the study (control 5.6±0.75 v. HE 6.3±0.5). From 12 weeks after starting the diet, ultrasonography of five different locations (retroperitoneal, axillary, withers, intercostal and rump) for adipose deposition, BCS and BW were measured monthly during the period that ponies received different diets. Statistical analysis was performed using a linear mixed-effects model with post hoc Bonferroni testing. P values <0.05 were considered significant. At week 12 after the onset of the diet, fat thickness in the HE group was significantly greater than in the control group. During the monitoring period, the HE group showed a significant increase in mean (±SE) BW (+52%, 265±13.94kg) and BCS (+70%; to 9.0±0.4), while the control group was unchanged (BW 160±13.98 kg; BCS 3.8±0.4). At all locations, the fat depth in the HE group increased significantly, with the highest increase noted for retroperitoneal deposits. The conclusions were that a 200% NE diet induced subcutaneous and retroperitoneal fat accumulation, with the greatest increase in intra-abdominal deposits. The moderate increase of the subcutaneous fat depth followed by a plateau phase suggests the existence of a limit of adipose tissue expandability, as in man
Parasitism of the backswimmer Buenoa scimitra (Hemiptera: Notonectidae) by the water mite Hydrachna virella (Acari: Hydrachnellae)
Meaning selection and the subcortex: Evidence of reduced lexical ambiguity repetition effects following subcortical lesions
Recent research indicates that individuals with nonthalamic subcortical (NS) lesions call experience difficulties processing lexical ambiguities in a variety of contexts. This study examined how prior processing of a lexical ambiguity influences subsequent meaning activation in 10 individuals with NS lesions and 10 matched healthy controls. Subjects made speeded lexical decisions oil related or unrelated targets following homophone primes. Homophones were repealed with different targets biasing the same or different meanings oil the second presentation. The effects of prime-target relatedness, interstimulus interval (200 or 1250 ms), and same vs different meaning repetition were examined Both the patient and control groups showed printing when the same homophone meaning was biased oil repetition. When a different meaning was biased on the second presentation. no priming was evident in the controls, while facilitation remained present for the NS group, consistent with aberrant meaning selection and deactivation processes. These findings are discussed in terms of age and task-related repetition effects and current conceptions of frontal-subcortical involvement in cognition
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