1,753 research outputs found
The Glyphosate Controversy: How Vermont Perspectives Could Inform Future Policy
Glyphosate is the most widely used herbicide in the world and remains the main active ingredient in Monsanto’s product Roundup. Not only is glyphosate used for agricultural production, including Roundup-Ready crops, it is also used in many other day-to-day applications outside of agriculture, including lawn-care maintenance. Though there are policies set in place by the EPA, different studies conducted by national and international agencies show that this herbicide poses significant health risks to humans and the broader environment. Grounded in the concepts of risk perception, and 90 survey responses from a door-to-door survey, this study investigates the public perceptions on pesticide use in Franklin County, Vermont and makes future policy-recommendations surrounding glyphosate usage in the State of Vermont. The study finds that citizens are rarely involved in chemical regulations; studies on risk perceptions and risk analysis can be resourceful in future policy-making
The Cosmic Lens All-Sky Survey parent population - I. Sample selection and number counts
We present the selection of the Jodrell Bank Flat-spectrum (JBF) radio source
sample, which is designed to reduce the uncertainties in the Cosmic Lens
All-Sky Survey (CLASS) gravitational lensing statistics arising from the lack
of knowledge about the parent population luminosity function. From observations
at 4.86 GHz with the Very Large Array, we have selected a sample of 117
flat-spectrum radio sources with flux densities greater than 5 mJy. These
sources were selected in a similar manner to the CLASS complete sample and are
therefore representative of the parent population at low flux densities. The
vast majority (~90 per cent) of the JBF sample are found to be compact on the
arcsecond scales probed here and show little evidence of any extended radio jet
emission. Using the JBF and CLASS complete samples we find the differential
number counts slope of the parent population above and below the CLASS 30 mJy
flux density limit to be -2.07+/-0.02 and -1.96+/-0.12, respectively.Comment: 10 pages, 4 figures, accepted for publication in MNRA
Poly-MTO, {(CH_3)_{0.92} Re O_3}_\infty, a Conducting Two-Dimensional Organometallic Oxide
Polymeric methyltrioxorhenium, {(CH_{3})_{0.92}ReO_{3}}_{\infty} (poly-MTO),
is the first member of a new class of organometallic hybrids which adopts the
structural pattern and physical properties of classical perovskites in two
dimensions (2D). We demonstrate how the electronic structure of poly-MTO can be
tailored by intercalation of organic donor molecules, such as
tetrathiafulvalene (TTF) or bis-(ethylendithio)-tetrathiafulvalene (BEDT-TTF),
and by the inorganic acceptor SbF. Integration of donor molecules leads to
a more insulating behavior of poly-MTO, whereas SbF insertion does not
cause any significant change in the resistivity. The resistivity data of pure
poly-MTO is remarkably well described by a two-dimensional electron system.
Below 38 K an unusual resistivity behavior, similar to that found in doped
cuprates, is observed: The resistivity initially increases approximately as
ln) before it changes into a dependence below 2 K.
As an explanation we suggest a crossover from purely two-dimensional
charge-carrier diffusion within the \{ReO\} planes at high
temperatures to three-dimensional diffusion at low temperatures in a
disorder-enhanced electron-electron interaction scenario (Altshuler-Aronov
correction). Furthermore, a linear positive magnetoresistance was found in the
insulating regime, which is caused by spatial localization of itinerant
electrons at some of the Re atoms, which formally adopt a electronic
configuration. X-ray diffraction, IR- and ESR-studies, temperature dependent
magnetization and specific heat measurements in various magnetic fields suggest
that the electronic structure of poly-MTO can safely be approximated by a
purely 2D conductor.Comment: 15 pages, 16 figures, 2 table
Supply Risk Considerations for the Elements in Nickel-Based Superalloys
Nickel-based superalloys contain various elements which are added in order to make the alloys more resistant to thermal and mechanical stress and to the adverse operating environments in jet engines. In particular, higher combustion temperatures in the gas turbine are important, since they result in higher fuel efficiency and thus in lower CO2 emissions. In this paper, a semi-quantitative assessment scheme is used to evaluate the relative supply risks associated with elements contained in various Ni-based superalloys: aluminium, titanium, chromium, iron, cobalt, niobium, molybdenum, ruthenium, tantalum, tungsten, and rhenium. Twelve indicators on the elemental level and four aggregation methods are applied in order to obtain the supply risk at the alloy level. The supply risks for the elements rhenium, molybdenum and cobalt are found to be the highest. For three of the aggregation schemes, the spread in supply risk values for the different alloy types (as characterized by chemical composition and the endurance temperature) is generally narrow. The fourth, namely the cost-share’ aggregation scheme, gives rise to a broader distribution of supply risk values. This is mainly due to the introduction of rhenium as a component starting with second-generation single crystal alloys. The resulting higher supply risk appears, however, to be acceptable for jet engine applications due to the higher temperatures these alloys can endur
Lensing galaxies: light or dark?
In a recent paper, Hawkins (1997) argues on the basis of statistical studies
of double-image gravitational lenses and lens candidates that a large
population of dark lenses exists and that these outnumber galaxies with more
normal mass-to-light ratios by a factor of 3:1. If correct, this is a very
important result for many areas of astronomy including galaxy formation and
cosmology. In this paper we discuss our new radio-selected gravitational lens
sample, JVAS/CLASS, in order to test and constrain this proposition. We have
obtained ground-based and HST images of all multiple-image lens systems in our
sample and in 12 cases out of 12 we find the lensing galaxies in the optical
and/or near infrared. Our success in finding lensing galaxies creates problems
for the dark lens hypothesis. If it is to survive, ad hoc modifications seem to
be necessary: only very massive galaxies (more than about one trillion solar
masses) can be dark, and the cutoff in mass must be sharp. Our finding of lens
galaxies in all the JVAS/CLASS systems is complementary evidence which supports
the conclusion of Kochanek et al. (1997) that many of the wide-separation
optically-selected pairs are physically distinct quasars rather than
gravitational lens systems.Comment: 4 pages, 2 included figures, accepted for publication in Astronomy
and Astrophysics. Paper version available on request. This replacement amends
the text to allow more discussion of the overlap with astro-ph/971016
MEVA - An interactive visualization application for validation of multifaceted meteorological data with multiple 3D devices
To achieve more realistic simulations, meteorologists develop and use models with increasing spatial and temporal resolution. The analyzing, comparing, and visualizing of resulting simulations becomes more and more challenging due to the growing amounts and multifaceted character of the data. Various data sources, numerous variables and multiple simulations lead to a complex database. Although a variety of software exists suited for the visualization of meteorological data, none of them fulfills all of the typical domain-specific requirements: support for quasi-standard data formats and different grid types, standard visualization techniques for scalar and vector data, visualization of the context (e.g., topography) and other static data, support for multiple presentation devices used in modern sciences (e.g., virtual reality), a user-friendly interface, and suitability for cooperative work
Effect of Conventional Mouthrinses on Initial Bioadhesion to Enamel and Dentin in situ
Aim: The study aimed to investigate the effect of a customary fluoride solution, containing sodium fluoride and amine fluoride, on initial biofilm formation on enamel and dentin in situ compared directly to chlorhexidine.
Methods: Bovine enamel and dentin specimens were mounted on maxillary splints carried by 9 subjects. After 1 min of pellicle formation, rinses with tap water (control), chlorhexidine (meridol med CHX 0.2%, GABA) and a fluoride mouthrinse (elmex, GABA) were performed for 1 min. Subsequently, the slabs were carried for another 8 h. The adherent bacteria were determined by DAPI staining, live-dead staining and determination of colony-forming units after desorption; glucan formation was visualized with concanavalin A. Additionally, energy-dispersive X-ray spectroscopy (EDX) analysis of the in situ biofilm layers was conducted, and contact angle measurements were performed. Statistical evaluation was performed by means of the Kruskal-Wallis test followed by the Mann-Whitney U test (p < 0.05).
Results: In the control group, significantly higher amounts of adherent bacteria were detected on dentin (4.8 x 10⁶ ± 5.4 x 10⁶ bacteria/cm²) than on enamel (1.2 x 10⁶ ± 1.5 x 10⁶ bacteria/cm² , DAPI). Chlorhexidine significantly reduced the amount of adherent bacteria (dentin: 2.8 x 10⁵ ± 3.4 x 10⁵ bacteria/cm² ; enamel: 4.2 x 10⁵ ± 8.7 x 10⁵ bacteria/cm²). Rinses with the fluoride solution also significantly reduced bacterial adherence to dentin (8.1 x 10⁵ ± 1.5 x 10⁶ bacteria/cm²). Fluoride could not be detected by EDX analysis of the biofilms. Fluoride mouthrinsing did not influence the wettability of the pellicle-covered enamel surface.
Conclusion: In addition to the reduction of demineralization and antibacterial effects, fluorides inhibit initial biofilm formation on dental hard tissues considerably, especially on dentin
Global Metal Use Targets in Line with Climate Goals.
Metals underpin essential functions in modern society, yet their production currently intensifies climate change. This paper develops global targets for metal flows, stocks, and use intensity in the global economy out to 2100. These targets are consistent with emissions pathways to achieve a 2 °C climate goal and cover six major metals (iron, aluminum, copper, zinc, lead, and nickel). Results indicate that despite advances in low-carbon metal production, a transformative system change to meet the society's needs with less metal is required to remain within a 2 °C pathway. Globally, demand for goods and services over the 21st century needs to be met with approximately 7 t/capita of metal stock-roughly half the current level in high-income countries. This systemic change will require a peak in global metal production by 2030 and deep decoupling of economic growth from both metal flows and stocks. Importantly, the identified science-based targets are theoretically achievable through such measures as efficient design, more intensive use, and longer product lifetime, but immediate action is crucial before middle- and low-income countries complete full-scale urbanization
An Evaluation of a Teaching Interaction Procedure Implemented in a Recess Setting
The teaching interaction procedure (TIP) is a strategy that has been demonstrated as effective in promoting social skill acquisition in school settings for young students with social communication deficits (Leaf et al., 2009; Leaf et al., 2010). However, a frequently cited criticism of social skills training is the lack of generalizability of target skills to novel contexts (Bellini et al., 2007). The purpose of the study was to evaluate a TIP-based social skills intervention conducted on the playground, intended to promote generalizability through training in naturalistic settings and to evaluate generalizability of skill acquisition to the classroom. Eight students 5-8 years old with an educational classification of autism or developmental delay participated in the study. The primary dependent variable was skill acquisition in the playground setting, and a secondary measure was generalized skill acquisition to the classroom setting. Target skills included appropriate body language, participation, and responding to initiations. A multi-probe design embedded within a multiple baseline design across target skills with concurrent replication across participants was used to evaluate the primary and secondary measures. Overall, results suggest that increases in skill acquisition were observed during implementation of the TIP across most participants and skills in both training and generalization phases. However, substantial variability was noted across participants related to maintaining skill acquisition during maintenance and follow-up phases in both the training and generalization settings. Limitations of these results are discussed as well as implications for school practitioners
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