Using the minimum spanning tree to trace mass segregation     

Richard J. Allison  Simon P. Goodwin  Richard J. Parker  Simon F. Portegies Zwart  Richard de Grijs  M. B. N. Kouwenhoven 《Monthly notices of the Royal Astronomical Society》2009,395(3):1449-1454

We present a new method to detect and quantify mass segregation in star clusters. It compares the minimum spanning tree (MST) of massive stars with that of random stars. If mass segregation is present, the MST length of the most massive stars will be shorter than that of random stars. This difference can be quantified (with an associated significance) to measure the degree of mass segregation. We test the method on simulated clusters in both 2D and 3D and show that the method works as expected.
We apply the method to the Orion Nebula Cluster (ONC) and show that the method is able to detect the mass segregation in the Trapezium with a 'mass segregation ratio (MSR)'  Λ_MSR= 8.0 ± 3.5  (where  Λ_MSR= 1  is no mass segregation) down to  16 M_⊙  , and also that the ONC is mass segregated at a lower level  (∼2.0 ± 0.5)  down to  5 M_⊙  . Below  5 M_⊙  we find no evidence for any further mass segregation in the ONC.  相似文献   

Solar Wind Effects Associated with a Recurrent,High-Latitude Coronal Brightness Enhancement     

Gary D. Parker 《Solar physics》2009,257(1):155-167

During the descent of Ulysses following the 2001 solar north pole passage, the SOHO LASCO C2 telescope recorded a particularly strong sequence of recurrent polarization brightness (pB) features at latitudes of around 55°. As Ulysses passed overhead, solar rotation swept the interplanetary extensions of these persistent coronal structures over the spacecraft. Comparison of solar remote sensing and Ulysses in situ observations through 2002 reveals the solar wind effects of very bright and recurrent K-coronal structures at high solar latitudes and of a steeply inclined heliospheric neutral sheet (HNS). Despite the high level of solar activity, the HNS at high latitude still organizes solar wind stream structure much as it did near the previous solar minimum. The recurrent coronal streamers originate slow solar wind and mark the northern extremity of a very tilted HNS whose passage at Ulysses is accompanied by slow, dense solar wind, enhanced temperature, depressed α abundance, enhanced magnetic fields, and magnetic field directional changes that evolve with spacecraft latitude.  相似文献   

Cloud structure of Saturn’s 2010 storm from ground-based visual imaging     

J.F. Sanz-Requena  S. Pérez-Hoyos  A. Sánchez-Lavega  T. del Río-Gaztelurrutia  D. Barrado-Navascués  F. Colas  J. Lecacheux  D. Parker 《Icarus》2012,219(1):142-149

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A New Method for Determining Compound Specific Carbon Isotope of Chlorinated Solvents in Porewater     

Jofre Herrero  Diana Puigserver  Beth L. Parker  José M. Carmona 《Ground Water Monitoring & Remediation》2021,41(3):51-57

A new method for the extraction of chlorinated solvents (CSs) from porewater with dimethylacetamide (DMA) used as a solvent and the determination of δ¹³C by gas chromatography-isotope ratio mass spectrometry (GC-IRMS) with solid-phase microextraction (SPME) are presented. This method was used for the determination of δ¹³C of chloroethenes and chloromethanes. The extraction of the CSs from porewater with DMA led to a minimal loss of mass of solvent and chlorinated compounds. The accuracy of the method was verified with the analysis of the pure injected compounds using elemental analyzer—isotope ratio mass spectrometry (EA-IRMS). It has been effectively applied in a study area in saturated soil samples of a pollutant source zone of perchloroethylene (PCE) and trichloroethylene (TCE). The limit of quantification of the new method was 0.034 μg/g for PCE and TCE for 10–20 g of soil sample. This new method allows for compound-specific isotope analysis of CSs in porewater, which can be beneficial in sites where the identification of contamination sources and the behavior of the contaminants are not clear.  相似文献   

The Influence of Place on the Willingness to Pay for Ecosystem Services     

Max Nielsen-Pincus  Patricia Sussman  Drew E. Bennett  Hannah Gosnell  Robert Parker 《社会与自然资源》2017,30(12):1423-1441

Sense of place, including an individual’s attitudes toward specific geographic settings, is generally predicted to influence willingness to engage in place-protective behaviors. Relatively little research, however, has empirically examined the influence of people’s attitudes toward a place on their willingness to pay for environmental protection. Using the example of a payment for ecosystem services (PES) initiative in the McKenzie River watershed, Oregon, USA, we found that place attitudes were a significant predictor of respondents’ willingness to pay for a program designed to benefit drinking water quality. These results suggest that connecting conservation actions to landscapes that are meaningful to people may increase their financial support for PES and other conservation programs. While program managers have little or no influence over stakeholders’ political ideology, gender, or income, managers may be able to influence prospective PES buyers’ awareness and attitudes through targeted communications, thereby potentially increasing support for place-based conservation efforts.  相似文献   

Visit to the British Museum: March 24th, 1874     

W.H. Hudleston  James Parker 《Proceedings of the Geologists' Association. Geologists' Association》1875,4(2):91-97

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On the relationship between the somme river and the somme valley     

James Parker 《Proceedings of the Geologists' Association. Geologists' Association》1875,4(5):286-IN1

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Adaptation and poverty reduction in Mozambique: an opportunity for developing countries to lead§     

Colin F. Quinn  Jennifer F. Howard  Chen Chen  Joyce E. Coffee  Carlos E. Quintela  Britt A. Parker 《Climate Policy》2018,18(2):146-150

Climate change disproportionately impacts the world’s poorest countries. A recent World Bank report highlighted that over 100 million people are at risk of falling into extreme poverty as a result of climate change. There is currently a lack of information about how to simultaneously address climate change and poverty. Climate change challenges provide an opportunity for those impacted most to come up with new and innovative technologies and solutions. This article uses an example from Mozambique where local and international partners are working side-by-side, to show how developing countries can simultaneously address climate change and poverty reduction using an ecosystem-based adaptation approach. Using ecosystem-based adaptation, a technique that uses the natural environment to help societies adapt to climate change, developing countries can lead the way to improve climate adaptation globally. This paradigm shift would help developing countries become leaders in ecosystem-based adaptation and green infrastructure techniques and has implications for climate policy worldwide.

POLICY RELEVANCE

The Paris Agreement resulting from the United Nations Framework Convention on Climate Change (UNFCCC) 21st Conference of Parties (COP 21) in December 2015 was rightly lauded for its global commitment to cut greenhouse gas emissions. However, COP 21 was also historic because of its call for non-party stakeholders to address climate change, inclusion of a global goal of ‘enhancing adaptive capacity, strengthening resilience and reducing vulnerability’, and the United States’ commitment of $800 million to adaptation funding. The combination of recognizing the need for new stakeholders to commit to climate change adaptation, the large impact climate change will have on the developing world, and providing access to funds for climate change adaptation creates a unique opportunity for developing countries to pave the way in adaptation policies in practices. Currently, developing countries are creating National Adaptation Plans (NAPs) for the UNFCCC. Through including a strong component of ecosystem-based adaptation in NAPs, developing countries can shape their countries’ policies, improve local institutions and governments, and facilitate a new generation of innovative leaders. Lessons learned in places like Mozambique can help lead the way in other regions facing similar climatic risks.  相似文献   

Faint UBVRI CCD sequences for wide-field surveys – II. UBVR sequences at δ=−30°     

Scott M. Croom  A. Ratcliffe  Q. A. Parker  T. Shanks  B. J. Boyle  R. J. Smith 《Monthly notices of the Royal Astronomical Society》1999,306(3):592-598

We present results from a continuing campaign to secure deep multi-colour CCD sequences for photometric calibration in UK Schmidt fields with galactic latitudes | b |>50°. In this paper we present UBVR photometry in 12 fields and BR photometry in a further 14 fields observed within UK Schmidt survey fields centred at δ =−30°. Photometric errors are at the 0.05 level at 20.2, 21, 20.5 and 20 mag for UBVR sequences respectively. Our observations were carried out with the 0.9-m telescope at the Cerro-Tololo Inter-American Observatory. These data are not intended for use as highly accurate individual photometric standards, but rather for use as sequences, using a large number of stars to calibrate wide-area data such as photographic plates. The data are available electronically at http://icstar5.ph.ic.ac.uk/~scroom/phot/photom.html .  相似文献   

Rights, the environment and Part V of the Criminal Justice and Public Order Act 1994     

Gavin Parker 《Area》1999,31(1):75-80

Summary Using figures derived from the UK Home Office, this paper analyses and reviews the impact and deployment of Part V of the Criminal Justice and Public Order Act 1994 since its enactment. This is done with special reference to its impact on citizenship and the regulation of 'the environment' and associated rural spaces. It is argued that, notwithstanding the actual use of the public order clauses in Part V of the Act, its underlying meanings are largely of a symbolic nature. Such symbolism is, however, a powerful indication of the defence of particularist constructions of rural space. It can also open out new conditions of possibility, providing a useful 'oppressed' status and media spectacle for a range of protesters and activists.  相似文献