Dry Nitrogen Deposition in the Grand Tetons: a Baseline Study

Plant ecosystems are largely dependent upon nitrogen, but recent decades have presented many ecosystems with unhealthy increases in nitrogen deposition. Though a majority of nitrogen is thought to be deposited via precipitation (wet deposition), it has been discovered that as much as 25% of total nitrogen deposition can be attributed to gases and particulate-matter (dry deposition). The extreme sensitivity of terrestrial, alpine ecosystems has produced a substantial interest in the effects of nitrogen deposition in Grand Teton National Park (GTNP). Currently, GTNP is one of the most at-risk parks in the country when considering the effects of increased nitrogen content (nutrient enrichment). As dry deposition has not been previously measured in GTNP, the current study conducted baseline measurements of nitrogenous dry deposition at two locations within the park. Ammonia contributed the most nitrogen, followed by ammonium, nitric acid, and nitrate, respectively. Total nitrogen dry deposition was estimated at 2.41kgN/ha/yr for the lower elevation site (Driggs) and 2.12kgN/ha/yr for the higher elevation site (Targhee)

Breaking of the overall permutation symmetry in nonlinear optical susceptibilities of one-dimensional periodic dimerized Huckel model

Based on infinite one-dimensional single-electron periodic models of trans-polyacetylene, we show analytically that the overall permutation symmetry of nonlinear optical susceptibilities is, albeit preserved in the molecular systems with only bound states, no longer generally held for the periodic systems. The overall permutation symmetry breakdown provides a fairly natural explanation to the widely observed large deviations of Kleinman symmetry for periodic systems in off-resonant regions. Physical conditions to experimentally test the overall permutation symmetry break are discussed.Comment: 7 pages, 1 figur

A Chandra View of the Multiple Merger In Abell 2744

We present a Chandra observation of the merging cluster of galaxies Abell 2744. The cluster shows strong evidence for an ongoing major merger which we believe to be responsible for the radio halo. X-ray emission and temperature maps of the cluster, combined with the spatial and redshift distribution of the galaxies, indicate a roughly north-south axis for the merger, with a significant velocity component along the line of sight. The merger is occurring at a very large velocity, with M = 2-3. In addition, there is a small merging subcluster toward the northwest, unrelated to the major merger, which shows evidence of a bow shock. A hydrodynamical analysis of the subcluster indicates a merger velocity corresponding to a Mach number of ~1.2, consistent with a simple infall model. This infalling subcluster may also be re-exciting electrons in the radio halo. Its small Mach number lends support to turbulent reacceleration models for radio halo formation.Comment: 8 pages, 6 figures (5 color). Submitted to MNRA

Educational Leaders Can Lead the Way for Increased Academic Achievement for Students on the Autism Spectrum

The problem that drove this study was the increasing number of students with autism entering the school system, and the barriers often encountered for both academic and social inclusion for students on the autism spectrum. Autism Spectrum Disorder, as defined by diagnostic criteria, includes deficits in social-relational communication; social-communication deficits can lead to educational impacts and limit opportunities upon transitioning from the public-school system. The purpose of this study was to examine the barriers to inclusion, from the perspectives of key stakeholders to include Local Education Agency (LEA) representatives, general and special education teachers, school counselors, school psychologists, speech-language pathologists and other educators who may be involved with Individualized Educational Plans (IEP). A phenomenological, qualitative study with a critical paradigm was conducted to discuss and examine individual experiences and perspectives concerning barriers encountered to inclusion as well as suggestions for better practices through and reported successes. The findings suggest several barriers to inclusion from each perspective and that collaboration of the IEP team is key to the development and implementation of successful IEPS that include both academic and social inclusion goals. Inclusive climates begin with a vision and mission of inclusion academically and socially from educational leadership

Hawking radiation from "phase horizons" in laser filaments?

Belgiorno et al have reported on experiments aiming at the detection of (the analogue of) Hawking radiation using laser filaments [F. Belgiorno et al, Phys. Rev. Lett. 105, 203901 (2010)]. They sent intense focused Bessel pulses into a non-linear dielectric medium in order to change its refractive index via the Kerr effect and saw creation of photons orthogonal to the direction of travel of the pluses. Since the refractive index change in the pulse generated a "phase horizon" (where the phase velocity of these photons equals the pulse speed), they concluded that they observed the analogue of Hawking radiation. We study this scenario in a model with a phase horizon and a phase velocity very similar to that of their experiment and find that the effective metric does not quite correspond to a black hole. The photons created in this model are not due to the analogue of black hole evaporation but have more similarities to cosmological particle creation. Nevertheless, even this effect cannot explain the observations -- unless the pulse has significant small scale structure in both the longitudinal and transverse dimensions.Comment: 13 pages RevTeX, 2 figure

Non-user benefits emanating from enhanced water flow to the Yala Protected Area Complex

Water is a multiple use resource. Increasing scarcity and competition from various sectors is an important dimension to be considered in its management. Understanding the value of water to different water uses is, therefore, necessary to assist decision-making in water allocation among sectors. Although water used in agriculture can be valued using production function approaches, such direct valuation methods are not available for the environmental uses of water. This paper uses non-market valuation methods to estimate the economic value of a committed flow through a unique ecosystem, the Yala Protected Area Complex (YPC). The Yala Protected Area Complex is an important wildlife refuge situated in south-eastern Sri Lanka. Its large land extent, undisturbed nature, and abundance and diversity of fauna contribute to its uniqueness. The fact that the YPC is also the most visited national park in Sri Lanka is partially a result of this uniqueness. However, maintenance of the park’s ecosystem depends on the flow of the Menik Ganga. This flow is regulated by the Veheragala Reservoir Project, and there is now discussion of reducing flow into the park by about half of the current level. The proposed plan ensures dry season flow into the YPC and, therefore, has been deemed acceptable. However, there is a possibility that farmers will demand further water releases during the dry season which could in turn endanger the planned downstream water releases. So there is a potential trade-off between environmental and irrigation uses of water. A willingness to pay (WTP) survey was conducted in ten districts in Sri Lanka during the fourth quarter of 2008 to estimate the WTP of the general population of the country towards maintaining this important environmental resource. In the hypothetical market presented, participants were told of the need for financial contributions from the general public to ensure the release of a minimum downstream flow commitment of 50 MCM. Participants were also informed of how this flow would enhance the ecosystem of the YPC. A single bound dichotomous choice contingent valuation approach was used as the elicitation format. Nonobligatory voluntary contributions were solicited towards a trust fund that could be used to ensure release of the required quantity of water downstream during dry months. According to the results of a binary logistic regression, income, age, and religious attachments are important factors affecting the decision to contribute to environmental flow maintenance to the YPC. Sixty-five percent of respondents were willing to pay something to ensure the maintenance of an adequate environmental flow in the YPC. The estimated mean WTP for water releases to enhance the YPC is Sri Lankan Rupees (SLR) 435 per year. Over the requested payment horizon of 10 years, the present value of aggregate WTP from the Sri Lankan population to enhance the ecosystem of the YPC is SLR 12 billion. This quantity greatly surpasses the present value of net benefits from rice farming estimated at SLR 0.64 billion, which would be generated if the same quantity of water was used for irrigation for 10 years (assuming current prices and input intensities). Thus, there is a clear opportunity for national welfare gain by ensuring adequate flow in YPC.Length: pp.37-47Water useMultiple useWildlifeHabitatsEcosystemsIrrigation waterWater allocation

Stability of the proton-to-electron mass ratio

We report a limit on the fractional temporal variation of the proton-to-electron mass ratio as, obtained by comparing the frequency of a rovibrational transition in SF6 with the fundamental hyperfine transition in Cs. The SF6 transition was accessed using a CO2 laser to interrogate spatial 2-photon Ramsey fringes. The atomic transition was accessed using a primary standard controlled with a Cs fountain. This result is direct and model-free