676 research outputs found
Replication Data for: Accounting for food web dynamics when assessing the impact of mesopredator control on declining prey populations
No full textThese are files to be able to reproduce the analyses and plots in Henden et al. 2020 in Journal of Applied Ecology.
Data on willow ptarmigan are based on line transect distance sampling.
Small rodent data are based on an abundance index from sampling using the small quadrat sampling scheme.
Carcass data comes from a national database of dead reindeer found
Harvest data comes from detailed records from the main management and landowner, FeFo, in Finnmark.
Data on red foxes comes from an ongoing fox decimation program on Varanger Peninsula.Abstract from accepted paper in Journal of Applied Ecology
Increasing populations of mesopredators are suspected to cause declines in vulnerable wildlife to the extent that mesopredator decimation actions (culling) have become commonplace. Design constraints, especially a lack of spatial replication, often hamper the assessment of the impact of such actions. However, extensive temporal replication (i.e. time series) and accounting for potentially confounding variables may alleviate this problem.
In alpine-arctic tundra, the red fox Vulpes vulpes is increasing, while many bird species are declining, likely due to increased predation. Here, we assessed the impact of a long-term (12-year) and spatially extensive (~3500km2) red fox culling action on the red listed willow ptarmigan Lagopus lagopus in the Norwegian Arctic. Ptarmigan populations were monitored annually in the impact area and in an adjacent no-action area, including a 5-year period before the action commenced. While logistical constraints prohibited monitoring of red fox population densities, the number of culled foxes and three influential food web covariates were monitored after the onset of the culling action.
A Before-After-Control-Impact-Paired-Series (BACIPS) analysis without food web covariates indicated that red fox culling curbed the decline of the population in the impact area, and that ptarmigan population density became ~25 % higher than in the reference area.
Spatially and temporally variable drivers within the food web confounded the simple BACIPS analysis. Accounting for three food web drivers as covariates in a linear mixed model after the onset of action, yielded a more unbiased impact estimate that amounted to ~40 % higher ptarmigan population density (4.3 more ptarmigan/km2) in the red fox impact area.
Synthesis and applications. We provide the first evidence of the role of the recent expansion of red fox in the decline of bird populations in tundra. We also show that red fox culling may be able to curb such declines, given that management actions are large-scale and long-term. As mesopredator culling campaigns are often expensive and controversial, it is important that their impacts are accurately assessed. We demonstrate that the accuracy of impact assessments can be profoundly increased by monitoring drivers of food web dynamics that impinge on the target species so that such drivers can be included as covariates in the analysis. This applies in particular to declining bird populations in boreal and arctic food webs ruled by strong multi-annual interaction cycles.
</ol
Hidrür oluşturarak atomik absorpsiyon spektrometrik ölçümlerde kuartz tüp atomlaştırıcıdaki inter-element girişimlerinin önlenmesi çalışmaları
No full textBu tezin, veri tabanı üzerinden yayınlanma izni bulunmamaktadır. Yayınlanma izni olmayan tezlerin basılı kopyalarına Üniversite kütüphaneniz aracılığıyla (TÜBESS üzerinden) erişebilirsiniz.IV ÖZET HİDRÜR OLUŞTURARAK ATOMİK ABSORPSİYON SPEKTROMETRİK ÖLÇÜMLERDE KUARTZ TÜP ATOMLAŞTIRICIDAKİ İNTER-ELEMENT GİRİŞİMLERİNİN ÖNLENMESİ ÇALIŞMALARI ERDEM YÜCETÜRK, Nur Yüksek Lisans Tezi, Kimya Bölümü Tez Yöneticisi :Prof.Dr. Emür HENDEN Ocak 2001, 56 sayfa Hidrür oluşturma atomik absorpsiyon spektrometresi arsenik ve antimon tayini için çok duyarlı bir yöntemdir. Bu yöntemin en büyük avantajı, örnek çözeltide bulunan matrix elementlerden hidrür oluşturan elementlerin ayrılmasıdır. Fakat birçok katyon bu tayinlere girişim yapar. Bu girişimler reaksiyon kabında hidrür oluşma aşamasında ve atomlaştırıcıda atomlaşma aşamasında meydana gelir. Bu çalışmada, kuartz tüp atomlaştırıcı kullanılarak hidrür oluşturma atomik absorpsiyon spektrometresi ile arsenik ve antimon tayininde, bu elementlerin karşılıklı girişimi araştırılmıştır. Girişimleri önlemek veya azaltmak için çeşitli yöntemler denenmiştir. Bunlar, girişim yapan hidrürün ısısal seçimli bozulması, metal kaplanmış cam pamuğu içeren adsorpsiyon tüpünün atomlaştırıcıdan önce yerleştirilmesi, atomlaşma sırasında kuartz tüp atomlaştırıcıya oksijen verilmesidir. Anahtar Sözcükler: Girişim; ara-element etkisi; hidrür oluşumuV ABSTRACT ATTEMPTS TO ELIMINATE INTER-ELEMENT INTERFERENCES IN THE HYDRIDE GENERATION ATOMIC ABSORPTION SPECTROMETRY SYSTEM WITH THE QUARTZ TUBE ATOMIZER ERDEM YÜCETÜRK, Nur MSc. Thesis in chemistry Supervisor: Prof. Dr. Emür HENDEN January 2001, 56 pages Atomic absorption spectrometry using the hydride generation technique and a quartz tube atomizer provides a very sensitive technique for arsenic and antimony determination. One of the main advantages of this technique is that the hydride-forming elements are separated from the matrix elements present in the sample solution. However, several cations interfere with these determinations. It appears that interferences take place both at the hydride generation step in the reaction vessel in the aqueous phase and at the atomization step in the atomizer. In this study, mutual interferences of arsenic and antimony on each other during their hydride generation atomic absorption spectrometric determination were examined using a quartz tubeatomizer. In order to eliminate or reduce interferences, different methods have been studied. These includes, selective thermal decomposition of the interfering hydride, use of an adsorption trap tube containing interfering metal coated glass wool before the atomizer, supplying oxygen into the quartz tube during atomization. Key Words: Interferences; inter-element effect; hydride generation
Replication Data for: Trail cameras can greatly inflate nest predation rates
No full textThese datasets and R-script relate to the analyses of a two year Tundra experiment that aimed to assess the effect of using trail-cameras on artificial nests to document predator identity and their predation rates. This study is published in The Journal of Wildlife Management.
ABSTRACT
Photographic monitoring currently provides the most accurate means for identifying nest predators and eventually their role in bird population declines worldwide. However, previous studies have found that such monitoring with use of commercially -available trail cameras represent an artificial structure near nests that often tendd to negatively bias predation rates, likely through predator neophobia. Based on an experiment in Arctic tundra, involving 50 artificial nests and 30 cameras in each of 2 breeding seasons, we here demonstrated that trail cameras rather attractedattracted corvids (in particular ravens), which caused an extreme andly, positively biased predation rate that was consistent over a range of experimental and environmental conditions. We call for new technologies that allow for photographic monitoring of bird nests with minimal visual footprints, in the form of smaller cameras and more efficient internal batteries to minimize novel and conspicuous external features detectable by predators. However, even such improved devices need to be assessed with respect to potential effects on nest predation in each case.
KEYWORDS Arctic tundra, bird population decline, climate change, corvids, monitoring, raven
Recommended from our members
Indenture between William Bithell and John Henden, 1596 March 16 :
No full textChirograph containing indenture between William Bithell of Winton and John Henden of Chichester recording property transaction for a tenement in Winton whose borders are delineated in the document. Dated "the sixtenth day of Ma[r]ch in the eight and thirtieth yere of the reign of our souereigne Lady Elizabeth by the grace of God of England, Ffrance, and Ireland Queene, defender of the faith." Sign and two slits with parchment tie at foot of document. Seal missing. Writing, possibly a signature on the fold. Small ink splotches on lines 16 and 26. Signatures and summary notes by a later hand on verso
Cataclysmic variables from a ROSAT/2MASS selection. I, Four new intermediate polars
No full textWe report the first results from a new search for cataclysmic variables (CVs) using a combined X-ray (ROSAT)/infrared (2MASS) target selection that discriminates against background active galactic nuclei. Identification spectra were obtained at the Isaac Newton Telescope for a total of 174 targets, leading to the discovery of 12 new CVs. Initially devised to find short-period low-mass-transfer CVs, this selection scheme has been very successful in identifying new intermediate polars. Photometric and spectroscopic follow-up observations identify four of the new CVs as intermediate polars: 1RXS J063631.9+353537 P(orb)similar or equal to 201 min, P-spin= 1008.3408 s or 930.5829 s), 1RXS J070407.9+262501 (P(orb)similar or equal to 250 min, P-spin= 480.708 s) 1RXS J173021.5-055933 (P-orb= 925.27 min, P-spin= 128.0 s), and 1RXS J180340.0+401214 (P-orb= 160.21 min, P-spin= 1520.51 s). RX J1730, also a moderately bright hard X-ray source in the INTEGRAL/IBIS Galactic plane survey, resembles the enigmatic AE Aqr. It is likely that its white dwarf is not rotating at the spin equilibrium period, and the system may represent a short-lived phase in CV evolution
Detecting the halo heating from AGN feedback with ALMA
No full textABSTRACT
The Sunyaev–Zel’dovich (SZ) effect can potentially be used to investigate the heating of the circumgalactic medium and subsequent suppression of cold gas accretion on to the host galaxy caused by quasar feedback. We use a deep ALMA observation of HE0515-4414 in band 4, the most luminous quasar known at the peak of cosmic star formation (z = 1.7), to search for the SZ signal tracing the heating of the galaxy’s halo. ALMA’s sensitivity to a broad range of spatial scales enables us to disentangle emitting compact sources from the negative, extended SZ signal. We obtain a marginal SZ detection (∼3.3σ) on scales of about 300 kpc (30–40 arcsec), at the 0.2 mJy level, 0.5 mJy after applying a correction factor for primary beam attenuation and flux that is resolved out by the array. We show that our result is consistent with a simulated ALMA observation of a similar quasar in the fable cosmological simulations. We emphasize that detecting an SZ signal is more easily achieved in the visibility plane than in the (inferred) images. We also confirm a marginal detection (3.2σ) of a potential SZ dip on smaller scales (<100 kpc) already claimed by other authors, possibly highlighting the complex structure of the halo heating. Finally, we use SZ maps from the fable cosmological simulations, convolved with ALMA simulations, to illustrate that band 3 observations are much more effective in detecting the SZ signal with higher significance, and discuss the optimal observing strategy
Physical properties of the trans-Neptunian object (38628) Huya from a multi-chord stellar occultation
No full textContext. As part of our international program aimed at obtaining accurate physical properties of trans-Neptunian objects (TNOs), we predicted a stellar occultation by the TNO (38628) Huya of the star Gaia DR2 4352760586390566400 (m(G) = 11.5 mag) on March 18, 2019. After an extensive observational campaign geared at obtaining the astrometric data, we updated the prediction and found it favorable to central Europe. Therefore, we mobilized half a hundred of professional and amateur astronomers in this region and the occultation was finally detected by 21 telescopes located at 18 sites in Europe and Asia. This places the Huya event among the best ever observed stellar occultation by a TNO in terms of the number of chords. Aims. The aim of our work is to determine an accurate size, shape, and geometric albedo for the TNO (38628) Huya by using the observations obtained from a multi-chord stellar occultation. We also aim to provide constraints on the density and other internal properties of this TNO. Methods. The 21 positive detections of the occultation by Huya allowed us to obtain well-separated chords which permitted us to fit an ellipse for the limb of the body at the moment of the occultation (i.e., the instantaneous limb) with kilometric accuracy. Results. The projected semi-major and minor axes of the best ellipse fit obtained using the occultation data are (a ', b ') = (217.6 +/- 3.5 km, 194.1 +/- 6.1 km) with a position angle for the minor axis of P ' = 55.2 degrees +/- 9.1. From this fit, the projected area-equivalent diameter is 411.0 +/- 7.3 km. This diameter is compatible with the equivalent diameter for Huya obtained from radiometric techniques (D = 406 +/- 16 km). From this instantaneous limb, we obtained the geometric albedo for Huya (p(V) = 0.079 +/- 0.004) and we explored possible three-dimensional shapes and constraints to the mass density for this TNO. We did not detect the satellite of Huya through this occultation, but the presence of rings or debris around Huya was constrained using the occultation data. We also derived an upper limit for a putative Pluto-like global atmosphere of about p(surf) = 10 nbar.Spanish grant (MCIU/AEI/FEDER, UE) [AYA-RTI2018-098657-J-I00]; State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award [SEV2017-0709]; Spanish grant [AYA-2017-84637-R, PID2020-112789GB-I00]; Proyectos de Excelencia de la Junta de Andalucia [2012-FQM1776, PY20-01309]; European Union's Horizon 2020 Research and Innovation Programme, project Small Bodies Near and Far (SBNAF) [687378]; European Research Council under the European Community's H2020 (2014-2020/ERC) [669416]; Romanian National Authority for Scientific Research and Innovation, CNCS - UEFISCDI [PN-III-P1-1.1-TE-2019-1504]; Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior - Brasil (CAPES) [001]; National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq) [465376/2014-2]; CNPq [309578/2017-5, 304544/2017-5, 401903/2016-8, 308150/2016-3, 305917/2019-6, 427700/2018-3, 310683/2017-3, 473002/2013-2, 150612/2020-6]; CAPES; FAPERJ/PAPDRJ [E26/203.173/2016]; Portuguese Foundation for Science and Technology (FCT); European Social Fund (ESF) [SFRH/BD/131700/2017]; Preeminant Postdoctoral Program of the University of Central Florida; National Research, Development and Innovation Office (NKFIH, Hungary) [K-125015, K-138962]; European Union's Horizon 2020 Research and Innovation Programme [871149]P.S-S. acknowledges financial support by the Spanish grant AYA-RTI2018-098657-J-I00 LEO-SBNAF (MCIU/AEI/FEDER, UE). P.S-S., J.L.O., N.M., M.V-L. and R.D. acknowledge financial support from the State Agency for Research of the Spanish MCIU through the Center of Excellence Severo Ochoa award for the Instituto de Astrofisica de Andalucia (SEV2017-0709), they also acknowledge the financial support by the Spanish grants AYA-2017-84637-R and PID2020-112789GB-I00, and the Proyectos de Excelencia de la Junta de Andalucia 2012-FQM1776 and PY20-01309. The research leading to these results has received funding from the European Union's Horizon 2020 Research and Innovation Programme, under Grant Agreement no. 687378, as part of the project Small Bodies Near and Far (SBNAF). Part of the research leading to these results has received funding from the European Research Council under the European Community's H2020 (2014-2020/ERC Grant Agreement no. 669416 LUCKY STAR). Part of the work of M.P. was financed by a grant of the Romanian National Authority for Scientific Research and Innovation, CNCS - UEFISCDI, PN-III-P1-1.1-TE-2019-1504. This study was financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) -Finance Code 001 and the National Institute of Science and Technology of the e-Universe project (INCT do e-Universo, CNPq grant 465376/2014-2). The following authors acknowledge the respective CNPq grants: F.B-R 309578/2017-5; R.V.-M. 304544/2017-5, 401903/2016-8; J.I.B.C. 308150/2016-3 and 305917/2019-6; M.A 427700/2018-3, 310683/2017-3 and 473002/2013-2; B.E.M. 150612/2020-6. G.B.R. thanks the support of CAPES and FAPERJ/PAPDRJ (E26/203.173/2016) grant. J.M.O. acknowledges financial support from the Portuguese Foundation for Science and Technology (FCT) and the European Social Fund (ESF) through the PhD grant SFRH/BD/131700/2017. E.F-V. acknowledges funding through the Preeminant Postdoctoral Program of the University of Central Florida. C.K., A.P. and R.S. have been supported by the grants K-125015 and K-138962 of the National Research, Development and Innovation Office (NKFIH, Hungary). E.P. acknowledges the Europlanet 2024 RI project funded by the European Union's Horizon 2020 Research and Innovation Programme (Grant agreement No. 871149). We are grateful to the CAHA and OSN staffs. This research is partially based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by Junta de Andalucia and Consejo Superior de Investigaciones Cientificas (IAA-CSIC). This research was also partially based on observation carried out at the Observatorio de Sierra Nevada (OSN) operated by Instituto de Astrofisica de Andalucia (CSIC). This article is also based on observations made in the Observatorios de Canarias del IAC with the Liverpool Telescope operated on the island of La Palma by the Instituto de Astrofisica de Canarias in the Observatorio del Roque de los Muchachos. Part of the results were based on observations taken at Pico dos Dias Observatory of the National Laboratory of Astrophysics (LNA/Brazil). Part of the data were collected during the photometric monitoring observations with the robotic and remotely controlled observatory at the University of Athens Observatory -UOAO (Gazeas 2016). We thank the Adiyaman University Astrophysics Application and Research Center for their support in the acquisition of data with the ADYU60 telescope. This work has made use of data from the European Space Agency (ESA) mission Gaia (https://www.cosmos.esa.; int/gaia), processed by the Gaia Data Processing and Analysis Consortium (DPAC, https://www.cosmos.esa.int/web/gaia/dpac/consortium).Funding for the DPAC has been provided by national institutions, in particular the institutions participating in the Gaia Multilateral Agreement
Activity of the Polar AM Her (RX J1816.2+4952): A Short Review
No full textWe show that AM Her displays the transitions between the high and low states with an intermittently existing dominant\ncycle with length between 400 and 800 days. Moreover, these transitions accumulate in clusters, which produces an\nadditional long cycle after smoothing; a single isolated short episode of the low state does not suggest a break of this cycle. The seasons of existence of the cycle can be controlled by the lifetime of the active regions (e.g. prominences, spots) on the donor. In some high-state episodes, a higher luminosity of the bremsstrahlung emission is not accompanied by a higher optical (cyclotron+stream) emission. Part of the bremsstrahlung emission can be buried in some episodes. Changes of\nthe structure of the accretion region(s) are necessary to explain the variations of the optical and X-ray activity in the\nhigh-state episodes of AM Her
Polarimetric evolution of V838 Monocerotis
No full textWe present the results of our polarimetric and spectropolarimetric monitoring of V838 Monocerotis, performed at the Asiago and Crimean observatories during and after the multiple outbursts that occurred in January-March 2002. The polarization of the object is mainly due to interstellar polarization (P ̃ 2.48%). Intrinsic polarization up to ̃ 0.7% at 5000 Å is present during the second maximum of the object (February 2002). This intrinsic component increases toward shorter wavelengths but our limited spectral coverage (5000-7500 Å) does not allow conclusive inferences about its origin. A strong depolarization across the Hα profile is observed. The interstellar polarization gives a lower limit to the reddening of E(B-V) >0.28, with E(B-V) ̃ 0.5 being the most probable value. A normal ratio of total to selective absorption (RV=3.22±0.17) was derived from the wavelength of maximum interstellar polarization. This suggests a low (if any) contribution by circumstellar material with a peculiar dust to gas ratio. A polarimetric map of a portion of the light echo shows a complex polarization distribution reaching Pmax=45%.
Based on observations collected at Padua Astronomical Observatory at Asiago and Crimean Astrophysical Observatory
- …
