1,223 research outputs found
Investigating the rheological properties and compatibility behaviours of RET/PE and WR/CR/ SBS compound-modified bitumen
No full textTwo types of elastomer/plastic compound-modified bitumen were developed by means of incorporating the reactive elastomeric terpolymer (RET) into the plastic (high-density polyethylene HDPE or recycled polyethylene RPE) modified bitumen and adding the wax residue (WR) into the bitumen/elastomer (crumb rubber CR or styrene–butadiene–styrene SBS) blends. The rheological properties, morphology microstructure and storage stability of these novel elastomer/plastic compound-modified binders were characterised. The results revealed that RET elastomer positively improved the high-temperature modulus, temperature insensitivity, rut resistant, elastic recovery and shear-resistance of HDPE- and RPE-modified bitumen. However, excessive RET dosage adversely influenced the cracking resistance of plastic-modified bitumen, and its optimum dosage was recommended as 1 wt%. Moreover, RET elastomer significantly strengthened the storage stability of HDPE and RPE-modified binders. The elasticity improvement effect of RET was attributed to the generated polymer network. On the other hand, adding WR limitedly deteriorated the rutting resistance and weakened the elastic recovery performance of elastomer (CR and SBS) modified bitumen. To ensure the low-temperature performance, the optimum level of WR was 2 wt%. Furthermore, the addition of WR promoted the compatibility and dispersion of CR and SBS modifiers in bitumen.Pavement Engineerin
WR 280 Practicum Report: Wildlife Management Techniques
No full textWildland RecreationAs part of the Wildland Recreation Spring Practicum, the author worked at the Fort St. John Fish and Wildlife Branch of the Ministry of Environment and Parks for two weeks, under the supervision of Rob Woods, Habitat Protection Technician. The author's volunteer work gave him an understanding of wildlife management techniques that included radio telemetry, classified counts, and ungulate aging/Harvest Cards
Vrist - brist - rist : Development of old initial wr in Scandinavian, particularly Swedish, dialects
No full textThe Germanic initial sound combination wr (e.g. in *wrītan 'write') has not been preserved in any standard language. In the Scandinavian languages the development of this sound combination has resulted in five different initial sounds or sound combinations, namely rw, r, w, br and vr. The aim of this study is to describe the occurrence of these sound combinations, and to explain their age and origin. A limited number of words, mainly from Swedish dialects, has been investigated. The Swedish material has been assembled in a collection that has largely also been mapped, and so has a collection of Norwegian dialect material. The result shows that br is frequent in the Swedish dialects and that it also occurs in Trøndelagen and Østlandet in Norway, and on Jutland. R is widespread in Norway and occurs in Sweden in some words in Norrland, Dalarna, Värmland, Dalsland, Uppland and on the island of Gotland. Rw has been documented in Upper Dalarna, and w in the same area, as well as in the Kalix dialect in northernmost Sweden. The author demonstrates that the Norwegian loss of w might have started already in the 6th century in western Norway. The loss on Gotland is independent and can be demonstrated in Old Gutnish. The metathesis rw is found in Swedish and Norwegian 13-14th century sources from Uppland, Västmanland, Östergötland and southeastern Norway. The developments wr > r and wr > rw probably have their roots in a difference between the west Norwegian wr and the east Norwegian and Swedish war which is documented from PrimScand times. W is a secondary development of rw. The change wr > br can be dated by place-name material to the early 15th century. The change wr > vr appears to have taken place at approximately the same time. The author demonstrates that the result, wr > br or wr > yr, is apparently governed by certain phonetic factors. The failure of the Germanic wr to survive depends on the combination being phonetically complex. The risk that w would be lost was therefore considerable. However, differentiating forces worked for its retention. All developments emanating from wr, apparently disparate, can be seen as features of a larger process where a general linguistic tendency towards a weakening of sounds is confronted by conservative forces, with the above results as a consequence.Doktorsavhandling vid Uppsala universitet 1991</p
GALACTIC COSMIC RAYS IN THE LOCAL INTERSTELLAR MEDIUM: VOYAGER 1 OBSERVATIONS AND MODEL RESULTS
No full textSince 2012 August Voyager 1 has been observing the local interstellar energy spectra of Galactic cosmic-ray nuclei down to 3 MeV nuc(-1) and electrons down to 2.7 MeV. The H and He spectra have the same energy dependence between 3 and 346 MeV nuc(-1), with a broad maximum in the 10-50 MeV nuc(-1) range and a H/He ratio of 12.2 +/- 0.9. The peak H intensity is similar to 15 times that observed at 1 AU, and the observed local interstellar gradient of 3-346 MeV H is -0.009 +/- 0.055% AU(-1), consistent with models having no local interstellar gradient. The energy spectrum of electrons (e(-) + e(+)) with 2.7-74 MeV is consistent with E-1.30 +/- 0.05 and exceeds the H intensity at energies below similar to 50 MeV. Propagation model fits to the observed spectra indicate that the energy density of cosmic-ray nuclei with >3 MeV nuc(-1) and electrons with >3 MeV is 0.83-1.02 eV cm(-3) and the ionization rate of atomic H is in the range of 1.51-1.64 x 10(-17) s(-1). This rate is a factor >10 lower than the ionization rate in diffuse interstellar clouds, suggesting significant spatial inhomogeneity in low-energy cosmic rays or the presence of a suprathermal tail on the energy spectrum at much lower energies. The propagation model fits also provide improved estimates of the elemental abundances in the source of Galactic cosmic rays
Dynamic Imprints of Colliding-wind Dust Formation from WR 140
No full textCarbon-rich Wolf-Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The “textbook” example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among the first to utilize two separate JWST observations, from Cycle 1 ERS (2022 July) and Cycle 2 (2023 September), to measure WR 140’s dust kinematics and confirm its morphology. To measure the proper motions and projected velocities of the dust shells, we performed a novel point-spread function (PSF) subtraction to reduce the effects of the bright diffraction spikes and carefully aligned the Cycle 2 to the Cycle 1 images. At 7.7 μm, through the bright feature common to 16 dust shells (C1), we find an average dust shell proper motion of 390 ± 29 mas yr−1, which equates to a projected velocity of 2714 ± 188 km s−1 at a distance of 1.64 kpc. Our measured speeds are constant across all visible shells and consistent with previously reported dust expansion velocities. Our observations not only prove that these dusty shells are astrophysical (i.e., not associated with any PSF artifact) and originate from WR 140, but also confirm the “clumpy” morphology of the dust shells, in which identifiable substructures within certain shells persist for at least 14 months from one cycle to the next. These results support the hypothesis that clumping in the wind collision region is required for dust production in WR binaries
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The orbit and stellar masses of the archetype colliding-wind binary WR 140
No full textWe present updated orbital elements for the Wolf-Rayet (WR) binary WR 140 (HD 193793; WC7pd + O5.5fc). The new orbital elements were derived using previously published measurements along with 160 new radial velocity measurements across the 2016 periastron passage of WR 140. Additionally, four new measurements of the orbital astrometry were collected with the CHARA Array. With these measurements, we derive stellar masses of and . We also include a discussion of the evolutionary history of this system from the Binary Population and Spectral Synthesis model grid to show that this WR star likely formed primarily through mass-loss in the stellar winds, with only a moderate amount of mass lost or transferred through binary interactions. © 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society.Immediate accessThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]
On the Relationship Between Recent Measurements of Cosmic Ray Electrons, Nonthermal Radio Emission from the Galaxy, and the Solar Modulation of Cosmic Rays
No full textUtilizing recent measurements of the cosmic ray electron spectrum at the Earth and the effects of solar modulation on this spectrum, possible limits on the local interstellar electron spectrum have been determined. Synchrotron emission from these interstellar electrons is then compared with the local (disk) volume emissivity of nonthermal radio emission as deduced from a study of radio intensity profiles along the galactic equator. The detailed spectrum and magnitude of radio emissivity can be reproduced from the electron spectrum only for very stringent, conditions on the magnitude of the local interstellar magnetic field, and the amount of solar modulation of cosmic rays. Specifically it is found that B -L "'" 7 !-,G, and the residual modulation parameter KR "'" 0�75 GV. If solar modulation effects on the cosmic ray electron component are negligible then an implausibly high local field of "'" 20 !-,G is required.</jats:p
Vrist - brist - rist [Elektronisk resurs] : Utvecklingen av gammalt uddljudande <em>wr</em> i nordiska, särskilt svenska, dialekter
No full textThe Germanic initial sound combination wr (e.g. in *wrītan 'write') has not been preserved in any standard language. In the Scandinavian languages the development of this sound combination has resulted in five different initial sounds or sound combinations, namely rw, r, w, br and vr.The aim of this study is to describe the occurrence of these sound combinations, and to explain their age and origin. A limited number of words, mainly from Swedish dialects, has been investigated. The Swedish material has been assembled in a collection that has largely also been mapped, and so has a collection of Norwegian dialect material.The result shows that br is frequent in the Swedish dialects and that it also occurs in Trøndelagen and Østlandet in Norway, and on Jutland. R is widespread in Norway and occurs in Sweden in some words in Norrland, Dalarna, Värmland, Dalsland, Uppland and on the island of Gotland. Rw has been documented in Upper Dalarna, and w in the same area, as well as in the Kalix dialect in northernmost Sweden.The author demonstrates that the Norwegian loss of w might have started already in the 6th century in western Norway. The loss on Gotland is independent and can be demonstrated in Old Gutnish. The metathesis rw is found in Swedish and Norwegian 13-14th century sources from Uppland, Västmanland, Östergötland and southeastern Norway. The developments wr > r and wr > rw probably have their roots in a difference between the west Norwegian wr and the east Norwegian and Swedish war which is documented from PrimScand times. W is a secondary development of rw. The change wr > br can be dated by place-name material to the early 15th century. The change wr > vr appears to have taken place at approximately the same time. The author demonstrates that the result, wr > br or wr > yr, is apparently governed by certain phonetic factors.The failure of the Germanic wr to survive depends on the combination being phonetically complex. The risk that w would be lost was therefore considerable. However, differentiating forces worked for its retention. All developments emanating from wr, apparently disparate, can be seen as features of a larger process where a general linguistic tendency towards a weakening of sounds is confronted by conservative forces, with the above results as a consequence.</p
Dynamic Imprints of Colliding-wind Dust Formation from WR 140
No full textThis article was originally published in The Astrophysical Journal Letters. The version of record is available at: https://doi.org/10.3847/2041-8213/ad9aa9.
© 2025. The Author(s). Published by the American Astronomical Society.
Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence (https://creativecommons.org/licenses/by/4.0/). Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.Carbon-rich Wolf–Rayet (WR) binaries are a prominent source of carbonaceous dust that contribute to the dust budget of galaxies. The "textbook" example of an episodic dust-producing WR binary, WR 140 (HD 193793), provides us with an ideal laboratory for investigating the dust physics and kinematics in an extreme environment. This study is among the first to utilize two separate JWST observations, from Cycle 1 ERS (2022 July) and Cycle 2 (2023 September), to measure WR 140's dust kinematics and confirm its morphology. To measure the proper motions and projected velocities of the dust shells, we performed a novel point-spread function (PSF) subtraction to reduce the effects of the bright diffraction spikes and carefully aligned the Cycle 2 to the Cycle 1 images. At 7.7 μm, through the bright feature common to 16 dust shells (C1), we find an average dust shell proper motion of 390 ± 29 mas yr−1, which equates to a projected velocity of 2714 ± 188 km s−1 at a distance of 1.64 kpc. Our measured speeds are constant across all visible shells and consistent with previously reported dust expansion velocities. Our observations not only prove that these dusty shells are astrophysical (i.e., not associated with any PSF artifact) and originate from WR 140, but also confirm the "clumpy" morphology of the dust shells, in which identifiable substructures within certain shells persist for at least 14 months from one cycle to the next. These results support the hypothesis that clumping in the wind collision region is required for dust production in WR binaries.The work of E.P.L. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the U.S. National Science Foundation. J.L.H. acknowledges support from the National Science Foundation under award AST-1816944. T.O. acknowledges support by the Japan Society for the Promotion of Science (JSPS) KAKENHI grant No. JP24K07087. N.D.R. is grateful for support from the Cottrell Scholar Award #CS-CSA-2023-143 sponsored by the Research Corporation for Science Advancement. J.S.-B. acknowledges the support received from the UNAM PAPIIT project IA 105023. C.M.P.R. acknowledges support from NASA Chandra Theory grant TM3-24001X. This material is based upon work supported by NASA under award number 80GSFC24M0006 and based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract number NAS 5-03127 for JWST. These observations are associated with programs #3823 and #1349. Support for program #3823 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127. We thank the anonymous reviewer for insightful feedback that improved the quality of this manuscript. We thank Christopher Packham and Mason Leist for their valuable discussions about the MIRI PSF subtraction
Data protection: the challenges facing social networking
No full textThe popularity of social networking sites has increased dramatically over the past decade. A recent report indicated that thirty-eight percent of online users have a social networking profile. Many of these social networking site users (SNS users) post or provide personal information over the internet every day. According to the latest OfCom study, the average adult SNS user has profiles on 1.6 sites and most check their profiles at least once every other day. However, the recent rise in social networking activity has opened the door to the misuse and abuse of personal information through identity theft, cyber stalking, and undesirable screenings by prospective employers. Behavioral advertising programs have also misused personal information available on social networking sites. Society is now facing an important question: what level of privacy should be expected and required within the social networking environment
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