1,389 research outputs found
Early Archean tonalite gneiss in the upper peninsula of Michigan
Geochronological results on tonalite gneiss of northern Michigan that is 3.56 Ga or slightly older is presented. Tonalitic augen gneiss and structurally overlying biotite gneiss and schist are exposed in a dome near Watersmeet. They are part of an extensive gneiss terrane of southern Minnesota, Wisconsin and Michigan that includes rocks of early to late Archean ages and lies south of the Wawa volcanic subprovince. Two samples of the augen gneiss and one of the biotite gneiss show zircon grains of similar shape, zoning, color, and development of crystal faces. These zircons give Pb/U isotopic ratios that plot on a chord of 3,560 + or - 40 m.y. upper intersect and of 1,250 + or m.y. lower intersect. The 3,560 m.y. number is believed to be a minimum age because analysis of one of the least discordant zircon fractions by ion microprobe that gave a nearly concordant age of 3,650 m.y. The 1,250 m.y. lower intersect is without geological significance: it is interpreted to be a result of multiple lead loss at 2.7, 1.8, and 0.5 Ga by U/Pb in zircon. Archean rocks 10 to 25 km northwest of the Watersmeet dome give a 2.75 Ga age on zircons. Quartz monzonite here is dated at 2.65 Ga
Characterizaiton of Cold-formed Steel Shear Wall Behavior under Cyclic Loading for the CFS-NEES Building
The objective of this paper is to provide a full hysteretic characterization of OSB sheathed cold-formed steel (CFS) shear walls designed for use in the National Science Foundation funded Network for Earthquake Engineering Simulation (NEES) project: CFS-NEES (www.ce.jhu.edu/cfsnees). The shear walls were designed for a two-story ledger-framed building (i.e., the CFS-NEES building) that will undergo full-scale shake table testing at the University of Buffalo NEES site. Shear walls in real construction, such as the CFS-NEES building, have details that differ from the shear walls tested and provided for strength prediction in standards such as AISI-S213-07. Differences include: (a) ledger (rim track) members are attached across the interior face of the studs, (b) OSB panel seams, both horizontal and vertical, may not be aligned with the chord studs or only blocked with strap, (c) interior gypsum board is in place, (d) field studs may have a different thickness or grade from the chord studs, and other differences. In this work, these four highlighted differences (a-d) are specifically explored in a series of shear walls tests loaded via cyclic (CUREE) protocols to determine their hysteretic performance. The test results are compared with AISIS213-07 and hysteretic material characterizations utilizing an elastic-plastic model (EEEP) and a model capable of exhibiting pinching in the hysteretic loops (Pinching4). Recommendations are made with respect to modeling the shear walls
Recommended from our members
Sweet corn (Zea mays) production in a white clover (Trifolium repens) living mulch : the second year
Soil-related problems common to Oregon farmers are
erosion, compaction, organic matter depletion, and
nutrient loss. High costs of fertilizer, fuel, and weed
control are additional management problems. Growing a
secondary crop as a living mulch with a primary crop may
ease some of these problems.
Sweet corn production in Oregon is commonly plagued
by these problems and may be suitable for a living mulch
system. Field experiments were begun to test the
feasibility of growing sweet corn (Zea mays L. 'Jubilee')
and white clover (Trifolium repens L. 'New Zealand')
living mulch in the Willamette Valley in Oregon.
Research was done at the Oregon State University Hyslop
and Horticulture research farms near Corvallis.
Management practices tested were fall-planted clover
(1982) compared to spring-planted clover (1983), and
clover suppression treatments in 1984. Suppression
treatments were 0.84 and 1.4 kg ai/ha atrazine (6-chloroN-
ethyl-N'-(1-methylethyl)-1,3,5-triazine-2,4-diamine),
and mowing.
Corn yields were not reduced when clover was planted
in the fall and suppressed with atrazine at 1.4 kg ai/ha.
When clover suppression treatments were mowing or 0.84 kg
ai/ha of atrazine, corn yields were reduced.
At the Horticulture farm, an additional screening
trial was conducted to determine the effect of selected
herbicides on second-year white clover. Results
indicated that the dimethylamine 2,4-D ((2,4-
dichlorophenoxy) acetic acid) applied at 2.24 kg ae/ha
gave excellent initial and residual suppression of the
clover (95% at 14 days after treatment and 82.5% at 67
days after treatment). A mixture of atrazine plus
alachlor (2-chloro-N-(2,6-diethylphenyl-N-
(methoxymethyl)acetamide) applied at 1.4 and 3.36 kg
ai/ha, respectively, effectively suppressed the clover
(80%), but was only slightly more severe than atrazine at
1.4 kg ai/ha
Quantum Electrodynamics of the Helium Atom
Using singlet S states of the helium atom as an example, I describe precise
calculation of energy levels in few-electron atoms. In particular, a complete
set of effective operators is derived which generates O(m*alpha^6) relativistic
and radiative corrections to the Schr"odinger energy. Average values of these
operators can be calculated using a variational Schr"odinger wave function.Comment: 23 pages, revte
Government of Malawi's unconditional cash transfer improves youth mental
We explore the impacts of Malawi's national unconditional cash transfer program targeting ultra-poor households on youth mental health. Experimental findings show that the program significantly improved mental health outcomes. Among girls in particular, the program reduces indications of depression by about 15 percentage points. We investigate the contribution of different possible pathways to the overall program impact, including education, health, consumption, caregiver's stress levels and life satisfaction, perceived social support, and participation in hard and unpleasant work. The pathways explain from 46 to 65 percent of the program impact, advancing our understanding of how economic interventions can affect mental health of youth in resource-poor settings. The findings underline that unconditional cash grants, which are used on an increasingly large scale as part of national social protection systems in Sub-Saharan Africa, have the potential to improve youth mental wellbeing and thus may help break the vicious cycle of poverty and poor mental health
Government of Malawi's unconditional cash transfer improves youth mental
We explore the impacts of Malawi's national unconditional cash transfer program targeting ultra-poor households on youth mental health. Experimental findings show that the program significantly improved mental health outcomes. Among girls in particular, the program reduces indications of depression by about 15 percentage points. We investigate the contribution of different possible pathways to the overall program impact, including education, health, consumption, caregiver's stress levels and life satisfaction, perceived social support, and participation in hard and unpleasant work. The pathways explain from 46 to 65 percent of the program impact, advancing our understanding of how economic interventions can affect mental health of youth in resource-poor settings. The findings underline that unconditional cash grants, which are used on an increasingly large scale as part of national social protection systems in Sub-Saharan Africa, have the potential to improve youth mental wellbeing and thus may help break the vicious cycle of poverty and poor mental health
Taking Uncertainty Seriously: From Permissive Regulation to Preventative Design in Environmental Decision Making
This paper contrasts two paradigms of environmental regulatory decision making, permissive regulation and preventative design, with respect to their treatment of scientific and legal uncertainty and the allocation of legal standards and burdens of proof. Permissive regulation, which is the predominant approach in Canada, suffers two types of statistical errors. A type I error occurs when, for example, a pollution control device is unjustly imposed on an industry. A type II error occurs when no action is taken to control an industry when, in fact, damage is taking place. Concern to prevent type I errors often leads to type II errors. Attempts to resolve these problems through incremental changes in legislation and policy have generally failed. This article illustrates the scientific and regulatory problems associated with \u27permissive regulation through an analysis of environmental common law, legislation, and regulation. Protection of environmental quality requires regulatory decision making rooted in the principles of precautionary, preventative action that tends to minimize costly type II errors. With the preventative design approach now being used in several jurisdictions, the regulatory burden of proving harm is shifted from regulators to the polluters who must demonstrate safety. European and American initiatives as well as international agreements illustrate the historical development and implementation of this preventative design perspective. This article suggests that Canadian legislation and regulations be written with this approach
Recommended from our members
Evidence for Gropun-Water Stratification Near Yucca Mountain, Nevada
Major- and trace-element concentrations and strontium isotope ratios (strontium-87/strontium-86) in samples of ground water potentially can be useful in delineating flow paths in the complex ground-water system in the vicinity of Yucca Mountain, Nevada. Water samples were collected from boreholes to characterize the lateral and vertical variability in the composition of water in the saturated zone. Discrete sampling of water-producing intervals in the saturated zone includes isolating borehole sections with packers and extracting pore water from core obtained by sonic drilling. Chemical and isotopic stratification was identified in the saturated zone beneath southern Fortymile Wash
The effect of mechanical and geometric uncertainty on perforated CFS bracing members
In the capacity design of cold-formed steel frames with X diagonal bracings, the ratio of overstrength to slenderness is particularly critical. The diagonal elements of these braces may be fabricated with perforations at the brace ends to satisfy design and detailing requirements for capacity protection of frames with concentric X bracings. In the paper, the influence of stochasticity in the geometrical features and mechanical properties on the overall structural response of specific cold-formed steel perforated elements is assessed. The impact of statistical variation in design parameters on the yield
strength, ultimate strength, and ductility is evaluated through a Monte Carlo simulation. Variability in member geometric features was determined from current design specifications, while variability in steel mechanical properties was determined via experimental testing. Monte Carlo simulations indicate a slight reduction of yield and ultimate member resistance increasing the number of holes. A normal probability distribution function, with a skewness greater than zero, which increases with a larger number of holes, characterizes both the yield and ultimate strength histogram. The work
concludes providing recommendations for designers to promote utilization of perforated braces in seismically-active area
Rapid interrogation of the physical and chemical characteristics of salbutamol sulphate aerosol from a pressurised metered-dose inhaler (pMDI)
Individual micron-sized solid particles from a Salamols pharmaceutical inhaler are stably captured in air using an optical trap for the first time. Raman spectroscopy of the levitated particles allows online interrogation of composition and deliquescent phase change within a high humidity environment that mimics the particle’s travel from inhaler to lun
- …