4,115 research outputs found
DECADAL REEVALUATION OF SUGAR MAPLE DIEBACK ETIOLOGY ACROSS THE UPPER GREAT LAKES REGION
Sugar maple (Acer saccharum) is a foundational tree species in northern hardwood forests of the United States and Canada. Though previous work has documented areas of substantial stress for this species in eastern North America, increasing reports of crown dieback in the Upper Great Lake states through the early 2000’s highlighted the relative lack of understanding of regional trends and causes. A 120-plot network of maple forest health monitoring sites was established and annually visited across Upper Michigan, northern Wisconsin, and eastern Minnesota between 2009 and 2012 to catalog and understand the regional phenomenon.
Results from the project’s initial years (Phase I) determined a significant correlation between sugar maple dieback and interrelated forest floor conditions (earthworm impact rating, soil carbon, herbaceous cover, and soil manganese) known to be influenced by exotic earthworms.
Ten years later, the network was resurveyed in 2021 and 2022 (Phase II). Sampling methods replicated prior methodology and added additional damaging agent signs and symptoms, including ungulate browse, lecanium species (Parthenolecanium spp.) and cottony maple scale (Pulvinaria innumerabilis), as well as more detailed sampling of earthworm species abundance, diversity, and impact.
Resurvey data suggest earthworm impact rating is still significantly correlated with sugar maple dieback across the network. Sugar maple dieback is ongoing and is 15.4% per tree averaged at the plot level (compared with 12.4% ten years ago) across the study area, though it is highly variable. Also, average canopy dieback for residual trees in harvest treatments worsened over the intervening years. Scale are not apparently linked to dieback condition. Future uses for the data include amendment of risk maps that land managers can incorporate into treatment plans using key correlates of decreased sugar maple health and vigor
Atomic hydrogen maser measurements with wall surfaces of carbon tetrafluoride
The principal objectives of the Smithsonian Astrophysical Observatory cold maser research programs are given. This work is aimed principally at understanding more about the interaction of hydrogen atoms with wall coatings of fluorinated ethylene propylene (Dupont Teflon FEP-120 co-polymer) and of carbon tetrafluoride (CE4). The principal measured quantity in these experiments is the wall shift of the maser's output frequency. The wall shift per atomic collision was calculated from the measured wall frequency shift. This assumes that the wall surface area is smooth on a molecular scale
Characteristics and Predictors for Students Classified with Emotional and Behavioral Disorder Who Have Also Experienced Maltreatment
Though experiencing maltreatment (abuse or neglect) appears to be common in students with the special education label of emotional and behavioral disorders (EBD), little research has been devoted to this topic by EBD educators. This paper uses archived file drawer data from 1992 that focuses on 149 students newly classified with EBD for whom a wide range of enrollment variables was collected, and who were subsequently followed up on an average of 8 years later to assess their educational outcomes. At enrollment, experiences of maltreatment were determined to have occurred in 57.7% of these participants. The group who experienced maltreatment was predicted at enrollment only by the family stress of having at least one natural parent with a history of psychiatric illness, although the concordance was not strong (52.3%). When the children who experienced maltreatment were next divided into two longitudinal groups according to educational outcomes (52.3% successful), the enrollment variables of the presence of anxiety and/or depressive disorder and younger age predicted the successful outcome group with good concordance (76.0%). Professional and programmatic implications for educators of students identified with EBD who have also experienced maltreatment are discussed, along with practical recommendations for serving this population
New Clock Comparison Searches for Lorentz and CPT Violation
We present two new measurements constraining Lorentz and CPT violation using
the Xe-129 / He-3 Zeeman maser and atomic hydrogen masers. Experimental
investigations of Lorentz and CPT symmetry provide important tests of the
framework of the standard model of particle physics and theories of gravity.
The two-species Xe-129 / He-3 Zeeman maser bounds violations of CPT and Lorentz
symmetry of the neutron at the 10^-31 GeV level. Measurements with atomic
hydrogen masers provide a clean limit of CPT and Lorentz symmetry violation of
the proton at the 10^-27 GeV level.Comment: 11 pages, 5 figures. To appear in the Proceedings of the 3rd
International Symposium on Symmetries in Subatomic Physic
Performance data of US Naval Observatory VLG-11 hydrogen masers since September, 1983
In 1983, two VLC-11 masers were delivered to the U.S. Naval Observatory by the Smithsonian Astrophysical Observatory. Last year the short-term stability of these masers was reported and the effect of this short-term stability on timekeeping performance was examined. Since the date of installation, 13 September 1983, data on the masers' long-term performance have been accumulated. The Allan variance, agma(tau), of the relative frequency between the masers reaches a minimum of about 4 parts in 10 to the 16th power at averaging times 5,000 seconds and rises at longer averaging times due, at least partly, to systematic frequency drift. The systematic frequency drifts, expressed in units of fractional frequency difference per day are discussed
Validity of the activPAL3 activity monitor in people moderately affected by Multiple Sclerosis
Background: Walking is the primary form of physical activity performed by people with Multiple Sclerosis (MS), therefore it is important to ensure the validity of tools employed to measure walking activity. The aim of this study was to assess the criterion validity of the activPAL3 activity monitor during overground walking in people with MS.\ud
Methods: Validity of the activPAL3 accelerometer was compared to video observation in 20 people moderately affected by MS. Participants walked 20-30m twice along a straight quiet corridor at a comfortable speed.\ud
Results: Inter-rater reliability of video observations was excellent (all intraclass correlations > 0.99). The mean difference (activPAL3- mean of raters) was -4.70 ± 9.09, -4.55 s ± 10.76 and 1.11 s ± 1.11 for steps taken, walking duration and upright duration respectively. These differences represented 8.7, 10.0 and 1.8% of the mean for each measure respectively. The activPAL3 tended to underestimate steps taken and walking duration in those who walked at cadences of ≤ 38 steps/minute by 60% and 47% respectively.\ud
Discussion: The activPAL3 is valid for measuring walking activity in people moderately affected by MS. It is accurate for upright duration regardless of cadence. In participants with slow walking cadences, outcomes of steps taken and walking duration should be interpreted with caution
Effects of industrial cashew nut processing on anacardic acid content and allergen recognition by IgE.
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Severity scoring of manganese health effects for categorical regression
Characterizing the U-shaped exposure response relationship for manganese (Mn) is necessary for estimating the risk of adverse health from Mn toxicity due to excess or deficiency. Categorical regression has emerged as a powerful tool for exposure-response analysis because of its ability to synthesize relevant information across multiple studies and species into a single integrated analysis of all relevant data. This paper documents the development of a database on Mn toxicity designed to support the application of categorical regression techniques. Specifically, we describe (i) the conduct of a systematic search of the literature on Mn toxicity to gather data appropriate for dose-response assessment; (ii) the establishment of inclusion/exclusion criteria for data to be included in the categorical regression modeling database; (iii) the development of a categorical severity scoring matrix for Mn health effects to permit the inclusion of diverse health outcomes in a single categorical regression analysis using the severity score as the outcome variable; and (iv) the convening of an international expert panel to both review the severity scoring matrix and assign severity scores to health outcomes observed in studies (including case reports, epidemiological investigations, and in vivo experimental studies) selected for inclusion in the categorical regression database. Exposure information including route, concentration, duration, health endpoint(s), and characteristics of the exposed population was abstracted from included studies and stored in a computerized manganese database (MnDB), providing a comprehensive repository of exposure-response information with the ability to support categorical regression modeling of oral exposure data
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