Weed Seedbanks of the U.S. Corn Belt: Magnitude, Variation, Emergence, and Application

Seedbanks and seedling emergence of annual weeds were examined in arable fields at eight locations in the Corn Belt. Seed densities were estimated by direct seed extraction from each of several soil cores in each sampled plot. Average total seedbank densities ranged from 600 to 162 000 viable seed m⁻² among locations. Coefficients of variation (CV) typically exceeded 50%. CV for seed densities of individual species usually exceeded 100%, indicating strongly aggregated distributions. CV were lower for species with dense seed populations than those with sparse seed populations. Variance of total seedbank densities was unstable when \u3c 10 cores were examined per plot, but stabilized at all locations when ≥ 15 cores were analyzed, despite a 12-fold difference in plot size and 270-fold difference in seed density among locations. Percentage viable seed that emerged as seedlings in field plots ranged from \u3c 1% for yellow rocket to 30% for giant foxtail. Redroot pigweed and common lambsquarters were the most frequently encountered species. Emergence percentages of these species were related inversely to rainfall or air temperatures in April or May, presumably because anoxia and/or high temperatures induced secondary dormancy in nondormant seed. From 50 to 90% of total seed in the seedbank were dead. This information can be employed by bioeconomic weed management models, which currently use coarse estimates of emergence percentages to customize recommendations for weed control

When one size does not fit all:Using <i>ex post</i> subjective ratings to provide parity in risk-adjusted compensation

Firms typically use a ‘one-size-fits-all’ (OSFA) compensation contract that specifies a common formulaic relation between performance and compensation (i.e., a performance bonus) for non-executive managers in similar jobs. However, a contract that is appropriate on average, may be suboptimal for individual managers if heterogeneity in the operating environment creates varying compensation risk. We use field data from a retail firm that introduced an OSFA bonus compensation plan for its store managers. The common bonus formula is based on a weighted sum of objective measures of performance and a subjective rating made by supervisors. The firm intended the supervisors’ discretionary subjective rating to evaluate performance on dimensions that are difficult to measure (e.g., store appearance). We test and find that supervisors give uniformly higher subjective ratings to managers whose objective measure of sales performance is measured with greater noise, and to managers who face higher performance target difficulty, the latter assessed both prior to (ex ante) and subsequent to (ex post) the evaluation period. These results obtain after controlling for manager ability and performance, and for alternative mechanisms to mitigate differences in compensation risk (e.g., salary changes, sales target changes, and bonus adjustments). The evidence suggests that supervisors use discretion in subjective ratings to provide manager-specific risk premiums for non-executive managers who are subject to an OSFA contract

Weed Seed Bank Emergence across the Corn Belt

Field experiments, conducted from 1991 to 1994, generated information on weed seedbank emergence for 22 site-years from Ohio to Colorado and Minnesota to Missouri. Early spring seedbank densities were estimated through direct extraction of viable seeds from soil cores. Emerged seedlings were recorded periodically, as were daily values for air and soil temperature, and precipitation. Percentages of weed seedbanks that emerged as seedlings were calculated from seedbank and seedling data for each species, and relationships between seedbank emergence and microclimatic variables were sought. Fifteen species were found in 3 or more site-years. Average emergence percentages (and coefficients of variation) of these species were as follows: giant foxtail, 31.2 (84%); velvetleaf, 28.2 (66); kochia, 25.7 (79); Pennsylvania smartweed, 25.1 (65); common purslane, 15.4 (135); common ragweed, 15.0 (110); green foxtail, 8.5 (72); wild proso millet, 6.6 (104); hairy nightshade, 5.2 (62); common sunflower, 5.0 (26); yellow foxtail, 3.4 (67); pigweed species, 3.3 (103); common lambsquarters, 2.7 (111); wild buckwheat, 2.5 (63), and prostrate knotweed, 0.6 (79). Variation among site-years, for some species, could be attributed to microclimate variables thought to induce secondary dormancy in spring. For example, total seasonal emergence percentage of giant foxtail was related positively to the 1st date at which average daily soil temperature at 5 to 10 cm soil depth reached 16 C. Thus, if soil warmed before mid April, secondary dormancy was induced and few seedlings emerged, whereas many seedlings emerged if soil remained cool until June

Weed Seed Bank Emergence across the Corn Belt

Field experiments, conducted from 1991 to 1994, generated information on weed seedbank emergence for 22 site-years from Ohio to Colorado and Minnesota to Missouri. Early spring seedbank densities were estimated through direct extraction of viable seeds from soil cores. Emerged seedlings were recorded periodically, as were daily values for air and soil temperature, and precipitation. Percentages of weed seedbanks that emerged as seedlings were calculated from seedbank and seedling data for each species, and relationships between seedbank emergence and microclimatic variables were sought. Fifteen species were found in 3 or more site-years. Average emergence percentages (and coefficients of variation) of these species were as follows: giant foxtail, 31.2 (84%); velvetleaf, 28.2 (66); kochia, 25.7 (79); Pennsylvania smartweed, 25.1 (65); common purslane, 15.4 (135); common ragweed, 15.0 (110); green foxtail, 8.5 (72); wild proso millet, 6.6 (104); hairy nightshade, 5.2 (62); common sunflower, 5.0 (26); yellow foxtail, 3.4 (67); pigweed species, 3.3 (103); common lambsquarters, 2.7 (111); wild buckwheat, 2.5 (63), and prostrate knotweed, 0.6 (79). Variation among site-years, for some species, could be attributed to microclimate variables thought to induce secondary dormancy in spring. For example, total seasonal emergence percentage of giant foxtail was related positively to the 1st date at which average daily soil temperature at 5 to 10 cm soil depth reached 16 C. Thus, if soil warmed before mid April, secondary dormancy was induced and few seedlings emerged, whereas many seedlings emerged if soil remained cool until June

Bone health in children with Angelman syndrome at the ENCORE Expertise Center

Angelman syndrome (AS) is a rare genetic disorder due to lack of UBE3A function on chromosome 15q11.2q13 caused by a deletion, uniparental paternal disomy (UPD), imprinting center disorder (ICD), or pathological variant of the UBE3A gene. AS is characterized by developmental delay, epilepsy, and lack of speech. Although fractures are observed frequently in our clinical practice, there are few studies on bone health in AS. The aim of this study is to investigate bone health in children with AS. In this prospective cohort study, we describe bone health in 91 children with AS visiting the ENCORE Expertise Center for AS between April 2010 and December 2021. Bone health was assessed with the bone health index (BHI) in standard deviation score (SDS) measured by digital radiogrammetry of the left hand using BoneXpert software. Risk factors analyzed were age, sex, genetic subtype, epilepsy, anti-seizure medication use, mobility, body mass index (BMI), and onset of puberty. Children with AS had a mean BHI of −1.77 SDS (SD 1.4). A significantly lower BHI was found in children with a deletion (−2.24 SDS) versus non-deletion (−1.02 SDS). Other factors associated with reduced BHI-SDS were inability to walk and late onset of puberty. Children with a history of one or more fractures (22%) had a significantly lower BHI than children without fractures (−2.60 vs −1.56 SDS). Longitudinal analysis showed a significant decrease in BHI-SDS with age in all genetic subtypes. Conclusions: Children with AS have a reduced bone health. Risk factors are deletion genotype, no independent walking, and late onset of puberty. Bone health decreased significantly with age. What is Known: • Children with neurological disorders often have a low bone health and higher risk of fractures. • Little is known about bone health in children with Angelman syndrome (AS). What is New: • Children with AS showed a reduced bone health and this was significantly associated with having a deletion, not being able to walk independently, and late onset of puberty. • Longitudinal analysis showed a significant decrease in bone health as children got older.</p

Cross-cultural conceptualization of a good end of life with dementia: A qualitative study

BACKGROUND: Research on the nature of a "good death" has mostly focused on dying with cancer and other life-limiting diseases, but less so on dementia. Conceptualizing common cross-cultural themes regarding a good end of life in dementia will enable developing international care models. METHODS: We combined published qualitative studies about end of life with dementia, focus group and individual interviews with the researchers, and video-conferencing and continuous email discussions. The interviews were audio-recorded and transcribed verbatim. The data were analyzed thematically, and the researchers developed common themes referring to their original studies. RESULTS: Fourteen qualitative researchers representing 14 cross-cultural studies covering qualitative data of 121 people with dementia and 292 family caregivers. The researchers and data were from eight countries UK, The Netherlands, Japan, Portugal, Germany, Canada, Brazil, and Ireland. Three focus groups, five individual interviews, and video-conferencing were conducted and feedback on multiple iterations was gained by 190 emails between May 2019 and April 2020 until consensus was achieved. Nine cross-culturally common themes emerged from the discussions and shared interpretation of the data of persons with dementia and family caregivers. Three represent basic needs: "Pain and Symptoms Controlled," "Being Provided Basic Care," and "A Place like Home." Other themes were "Having Preferences Met," "Receiving Respect as a Person," "Care for Caregivers," "Identity Being Preserved," "Being Connected," and "Satisfaction with Life and Spiritual Well-being." "Care for Caregivers" showed the greatest difference in emphasis across cultures. Good relationships were essential in all themes. CONCLUSIONS: The common cross-cultural themes comprise a framework underpinned by value placed on personhood and dignity, emphasizing that interdependency through relationships is essential to promote a good end of life with dementia. These themes and valuing the importance of relationships as central to connecting the themes could support care planning and further development of a dementia palliative care model. TRIAL REGISTRATION: The Graduate School and Faculty of Medicine Kyoto University (R1924-1)