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Sidney S Mirvish - One of the best experts on this subject based on the ideXlab platform.
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Urinary Excretion of N‑Nitroso Compounds in Rats Fed Sodium Nitrite and/or Hot Dogs
2016Co-Authors: Lin Zhou, Valerie K Shostrom, Muhammad M Anwar, Muhammad Zahid, Sidney S MirvishAbstract:ABSTRACT: Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or Hot Dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or Hot Dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed Hot Dogs. Their 24 h urine samples were analyzed for ANC by thermal energy analysis on days 1− 4 after nitrite or Hot dog treatment was stopped. For two rats fed 480 mg NaNO2/L drinking water, mean urinary ANC excretion on days 1− 4 was 30, 5.2, 2.5, and 0.8 nmol/day, respectively. For two to eight rats/ dose given varied NaNO2 doses, mean urinary ANC output on day 1 increased from 0.9 (for no nitrite) to 37 (for 1000 mg NaNO2/L drinking water) nmol ANC/day. Urine samples of four rats fed 40−60 % Hot Dogs contained 12−13 nmol ANC on day 1. Linear regression analysis showed highly significant correlations between urinary ANC excretion on day 1 after stopping treatment and varied (a) NaNO2 level in drinking water for rats fed semipurified or commercials diet and (b) Hot dog levels in the diet. Some correlations remained significant up to 4 days after nitrite treatment was stopped. Urinary output of ANC precursors (compounds that yield ANC after mild nitrosation) for rats fed semipurified or commercial diet was 11−17 or 23−48 μmol/day, respectively. Nitrosothiols and iron nitrosyls were not detected in urinary ANC and ANCP. Excretion of urinary ANC was about 60 % of fecal ANC excretion for 1 to 2 days after NaNO2 was fed. Administered NaNO2 was not excreted unchanged in rat urine. We conclude that urinary ANC excretion in humans could usefully be surveyed to indicate exposure to N-nitroso compounds. 1
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urinary excretion of n nitroso compounds in rats fed sodium nitrite and or Hot Dogs
Chemical Research in Toxicology, 2014Co-Authors: Lin Zhou, Valerie K Shostrom, Muhammad M Anwar, Muhammad Zahid, Sidney S MirvishAbstract:Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or Hot Dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or Hot Dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed Hot Dogs. Their 24 h urine samples were analyzed for ANC by thermal energy analysis on days 1–4 after nitrite or Hot dog treatment was stopped. For two rats fed 480 mg NaNO2/L drinking water, mean urinary ANC excretion on days 1–4 was 30, 5.2, 2.5, and 0.8 nmol/day, respectively. For two to eight rats/dose given varied NaNO2 doses, mean urinary ANC output on day 1 increased from 0.9 (for no nitrite) to 37 (for 1000 mg NaNO2/L drinking water) nmol ANC/day. Urine samples of four rats fed 40–60% Hot Dogs contained 12–13 nmol ANC on day 1. Linear regression analysis showed highly sign...
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Induction of colonic aberrant crypts in mice by feeding apparent N-nitroso compounds derived from Hot Dogs.
Nutrition and Cancer, 2012Co-Authors: Michael E Davis, Michal P Lisowyj, Lin Zhou, James L Wisecarver, James M Gulizia, Valerie K Shostrom, Nathalie Naud, Denis E Corpet, Sidney S MirvishAbstract:Nitrite-preserved meats (e.g., Hot Dogs) may help cause colon cancer because they contain N-nitroso compounds. We tested whether purified Hot-dog-derived total apparent N-nitroso compounds (ANC) could induce colonic aberrant crypts, which are putative precursors of colon cancer. We purified ANC precursors in Hot Dogs and nitrosated them to produce ANC. In preliminary tests, CF1 mice received 1 or 3 i.p. injections of 5 mg azoxymethane (AOM)/kg. In Experiments 1 and 2, female A/J mice received ANC in diet. In Experiment 1, ANC dose initially dropped sharply because the ANC precursors had mostly decomposed but, later in Experiment 1 and throughout Experiment 2, ANC remained at 85 nmol/g diet. Mice were killed after 8 (AOM tests) or 17-34 (ANC tests) wk. Median numbers of aberrant crypts in the distal 2 cm of the colon for 1 and 3 AOM injections, CF1 controls, ANC (Experiment 1), ANC (Experiment 2),and untreated A/J mice were 31, 74, 12, 20, 12, and 5-6, with P < 0.01 for both ANC tests. Experiment 2 showed somewhat increased numbers of colonic mucin-depleted foci in the ANC-treated group. We conclude that Hot-dog-derived ANC induced significant numbers of aberrant crypts in the mouse colon.
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abstract 3446 induction of colonic aberrant crypts in mice by an apparent n nitroso compound fraction derived from Hot Dogs
Cancer Research, 2010Co-Authors: Michael E Davis, Michal P Lisowyj, James L Wisecarver, James M Gulizia, Sidney S MirvishAbstract:Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Introduction: Nitrite-preserved meat products, e.g., Hot Dogs, may be a cause of colon cancer. This may occur because such products contain a possibly carcinogenic fraction called “total apparent N-nitroso compounds” (ANC). Feeding such products to humans and mice increased the fecal excretion of ANC. We tested here whether Hot-dog-derived ANC could induce colonic aberrant crypts (ABC), a precursor lesion for colon cancer, in mice. Methods: We purified the ANC precursor (ANCP) fraction of commercial Hot hogs by adsorption-desorption on silica gel and cation exchange resin, and treated the ANCP with nitrite to convert them to ANC. As a positive control group, adult female A/J mice were given 1 or 3 i.p. injections of 5 mg/kg of azoxymethane (AOM) [Experiment (Exp.) 1]. In Exps. 2 and 3, similar mice were continuously fed the purified Hot dog ANC (initial dose, 100 nmol/g diet) in a high-fat or “high-fat stress” diet. In Exp. 2 the ANC dose initially dropped sharply, probably because the ANCP was unstable on thawing, but later in Exp 2 and throughout Exp 3 the ANCP level was stable and was maintained at 100 nmol/g diet. The mice were killed after 8 (for AOM tests) or 24-34 (for ANC tests) weeks of treatment. Feces of the ANC-treated mice contained up to 225 nmol ANC/g, indicating that the ANC reached the colon. The distal 2 cm of each colon was stained with methylne blue, the mucosal surfaces were scanned at 400 x magnification, and ABC were identified and counted. Results: Mean numbers of ANC/colon for 1 and 3 AOM injections, AOM controls, ANC (Exp 2), ANC (Exp. 3) and ANC controls were 28, 76, 14, 20, 14 and 5-8. Standard deviations were <50% of mean values. The effect of ANC was significant by the rank order test (P < 0.01) for both Exps. 2 and 3. Potency of ABC induction per mole ANC was 1.7% (Exp. 2) and 0.4% (Exp. 3) of that for AOM in Exp. 1. In Exp. 3 we noted that the ABC occurred as foci with 1-4 ABC/focus and a mean of 6.8 foci/colon. ANC treatment did not affect the number of foci. Conclusions: Hot-dog-derived ANC induced a significant number of ABC in the mouse colon, but the effect was relatively weak. These results provide a direct link between ANC in a nitrite-preserved meat product and effects in the colon. Partly supported by NIH grant RO1 CA-143460-01. Note: This abstract was not presented at the AACR 101st Annual Meeting 2010 because the presenter was unable to attend. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3446.
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partial purification from Hot Dogs of n nitroso compound precursors and their mutagenicity after nitrosation
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Lin Zhou, James Haorah, Fulvio Perini, Steven G Carmella, Takayuki Shibamoto, Sidney S MirvishAbstract:Hot Dogs contain apparent N-nitroso compounds (ANC) and ANC precursors (ANCP). ANCP purification was followed by nitrosation, sulfamic acid treatment, and analysis for ANC. Aqueous Hot dog extracts were adsorbed on silica gel, which was eluted with MeCN and MeOH. The MeOH eluate was adsorbed on cation exchange resin (H+ form) and eluted with NH4OH. Eluted ANCP traveled at moderate speeds in high-performance liquid chromatography (HPLC) on amino and Pb2+ columns. Gas chromatography−mass spectrometry (GC-MS) of trimethylsilyl (TMS) derivatives of crude water extract indicated the presence of glycerol, phosphate, lactic acid, and two monosaccharides. GC-MS of TMS derivatives of Pb2+ column HPLC eluates indicated that ANCP included 1-deoxy-N-1-glucosyl glycine. The nitrosated NH4OH eluate showed 4× background mutagenic activity for Salmonella typhimurium TA-100. Un-nitrosated fractions showed 2× background activity. Although tryptophan nitrosation gave 88% ANC yield, tryptophan is probably not a major ANCP in...
Lin Zhou - One of the best experts on this subject based on the ideXlab platform.
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Urinary Excretion of N‑Nitroso Compounds in Rats Fed Sodium Nitrite and/or Hot Dogs
2016Co-Authors: Lin Zhou, Valerie K Shostrom, Muhammad M Anwar, Muhammad Zahid, Sidney S MirvishAbstract:ABSTRACT: Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or Hot Dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or Hot Dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed Hot Dogs. Their 24 h urine samples were analyzed for ANC by thermal energy analysis on days 1− 4 after nitrite or Hot dog treatment was stopped. For two rats fed 480 mg NaNO2/L drinking water, mean urinary ANC excretion on days 1− 4 was 30, 5.2, 2.5, and 0.8 nmol/day, respectively. For two to eight rats/ dose given varied NaNO2 doses, mean urinary ANC output on day 1 increased from 0.9 (for no nitrite) to 37 (for 1000 mg NaNO2/L drinking water) nmol ANC/day. Urine samples of four rats fed 40−60 % Hot Dogs contained 12−13 nmol ANC on day 1. Linear regression analysis showed highly significant correlations between urinary ANC excretion on day 1 after stopping treatment and varied (a) NaNO2 level in drinking water for rats fed semipurified or commercials diet and (b) Hot dog levels in the diet. Some correlations remained significant up to 4 days after nitrite treatment was stopped. Urinary output of ANC precursors (compounds that yield ANC after mild nitrosation) for rats fed semipurified or commercial diet was 11−17 or 23−48 μmol/day, respectively. Nitrosothiols and iron nitrosyls were not detected in urinary ANC and ANCP. Excretion of urinary ANC was about 60 % of fecal ANC excretion for 1 to 2 days after NaNO2 was fed. Administered NaNO2 was not excreted unchanged in rat urine. We conclude that urinary ANC excretion in humans could usefully be surveyed to indicate exposure to N-nitroso compounds. 1
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urinary excretion of n nitroso compounds in rats fed sodium nitrite and or Hot Dogs
Chemical Research in Toxicology, 2014Co-Authors: Lin Zhou, Valerie K Shostrom, Muhammad M Anwar, Muhammad Zahid, Sidney S MirvishAbstract:Nitrite-treated meat is a reported risk factor for colon cancer. Mice that ingested sodium nitrite (NaNO2) or Hot Dogs (a nitrite-treated product) showed increased fecal excretion of apparent N-nitroso compounds (ANC). Here, we investigated for the first time whether rats excrete increased amounts of ANC in their urine after they are fed NaNO2 and/or Hot Dogs. Rats were treated for 7 days with NaNO2 in drinking water or were fed Hot Dogs. Their 24 h urine samples were analyzed for ANC by thermal energy analysis on days 1–4 after nitrite or Hot dog treatment was stopped. For two rats fed 480 mg NaNO2/L drinking water, mean urinary ANC excretion on days 1–4 was 30, 5.2, 2.5, and 0.8 nmol/day, respectively. For two to eight rats/dose given varied NaNO2 doses, mean urinary ANC output on day 1 increased from 0.9 (for no nitrite) to 37 (for 1000 mg NaNO2/L drinking water) nmol ANC/day. Urine samples of four rats fed 40–60% Hot Dogs contained 12–13 nmol ANC on day 1. Linear regression analysis showed highly sign...
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Induction of colonic aberrant crypts in mice by feeding apparent N-nitroso compounds derived from Hot Dogs.
Nutrition and Cancer, 2012Co-Authors: Michael E Davis, Michal P Lisowyj, Lin Zhou, James L Wisecarver, James M Gulizia, Valerie K Shostrom, Nathalie Naud, Denis E Corpet, Sidney S MirvishAbstract:Nitrite-preserved meats (e.g., Hot Dogs) may help cause colon cancer because they contain N-nitroso compounds. We tested whether purified Hot-dog-derived total apparent N-nitroso compounds (ANC) could induce colonic aberrant crypts, which are putative precursors of colon cancer. We purified ANC precursors in Hot Dogs and nitrosated them to produce ANC. In preliminary tests, CF1 mice received 1 or 3 i.p. injections of 5 mg azoxymethane (AOM)/kg. In Experiments 1 and 2, female A/J mice received ANC in diet. In Experiment 1, ANC dose initially dropped sharply because the ANC precursors had mostly decomposed but, later in Experiment 1 and throughout Experiment 2, ANC remained at 85 nmol/g diet. Mice were killed after 8 (AOM tests) or 17-34 (ANC tests) wk. Median numbers of aberrant crypts in the distal 2 cm of the colon for 1 and 3 AOM injections, CF1 controls, ANC (Experiment 1), ANC (Experiment 2),and untreated A/J mice were 31, 74, 12, 20, 12, and 5-6, with P < 0.01 for both ANC tests. Experiment 2 showed somewhat increased numbers of colonic mucin-depleted foci in the ANC-treated group. We conclude that Hot-dog-derived ANC induced significant numbers of aberrant crypts in the mouse colon.
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partial purification from Hot Dogs of n nitroso compound precursors and their mutagenicity after nitrosation
Journal of Agricultural and Food Chemistry, 2006Co-Authors: Lin Zhou, James Haorah, Fulvio Perini, Steven G Carmella, Takayuki Shibamoto, Sidney S MirvishAbstract:Hot Dogs contain apparent N-nitroso compounds (ANC) and ANC precursors (ANCP). ANCP purification was followed by nitrosation, sulfamic acid treatment, and analysis for ANC. Aqueous Hot dog extracts were adsorbed on silica gel, which was eluted with MeCN and MeOH. The MeOH eluate was adsorbed on cation exchange resin (H+ form) and eluted with NH4OH. Eluted ANCP traveled at moderate speeds in high-performance liquid chromatography (HPLC) on amino and Pb2+ columns. Gas chromatography−mass spectrometry (GC-MS) of trimethylsilyl (TMS) derivatives of crude water extract indicated the presence of glycerol, phosphate, lactic acid, and two monosaccharides. GC-MS of TMS derivatives of Pb2+ column HPLC eluates indicated that ANCP included 1-deoxy-N-1-glucosyl glycine. The nitrosated NH4OH eluate showed 4× background mutagenic activity for Salmonella typhimurium TA-100. Un-nitrosated fractions showed 2× background activity. Although tryptophan nitrosation gave 88% ANC yield, tryptophan is probably not a major ANCP in...
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n nitroso compounds in the gastrointestinal tract of rats and in the feces of mice with induced colitis or fed Hot Dogs or beef
Carcinogenesis, 2003Co-Authors: Sidney S Mirvish, Lin Zhou, James Haorah, Melissa Hartman, Chantey R Morris, Marge L ClapperAbstract:Because colonic N-nitroso compounds (NOC) may be a cause of colon cancer, we determined total NOC levels by Walters' method in the gastrointestinal tract and feces of rodents: (i) feces of C57BL mice fed chow and semi-purified diets contained 3.2 +/- 0.4 and 0.46 +/- 0.06 NOC/g, respectively (P < 0.01, mean +/- SD). (ii) NOC levels for gastrointestinal contents of three groups of Sprague-Dawley rats fed chow diet were 0.9 +/- 0.05 (diet), 0.2 +/- 0 (stomach), 0.3-0.4 (small intestine), 0.7-1.6 (cecum and colon) and 2.6 +/- 0.6 (feces) nmol/g. NOC precursor (NOCP) levels (measured as NOC after mild nitrosation) for two rat groups fed chow diet showed a 16-fold increase from stomach to proximal small intestine (mean, 6.2 micromol/g), and a 1.7-fold increase from distal colon to feces (mean, 11.6 micromol/g). (iii) Eight Min and five C57BL/6J mice received 4% dextran sulfate sodium in drinking water on days 1-4 to induce acute colitis. This increased fecal NOC levels 1.9-fold on day 5 in both strains (P < or = 0.04), probably due to NO synthase-derived nitrosating agents in the colon. (iv) Following studies on humans fed beef [Hughes et al. (2001) Carcinogenesis, 22, 199], Swiss mice received semi-purified diets mixed with 18% of beef plus pork Hot Dogs or sauteed beef for 7 days. On day 7, individual 24-h fecal NOC outputs were determined. In three Hot dog and two beef groups with 5 mice/group, mean fecal NOC output/day was 3.7-5.0 (Hot dog) and 2.0-2.9 (beef) times that for control groups fed semi-purified diet alone (P < 0.002 for each of combined groups). These groups showed little change in fecal NOCP output. (v) Initial purification of rat fecal NOCP by adsorption-desorption and HPLC is described. Results should help evaluate the view that colonic NOC causes colon cancer associated with colitis and ingestion of red and nitrite-preserved meat.
Lulu Fan - One of the best experts on this subject based on the ideXlab platform.
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infrared spectral energy distribution decomposition of wise selected hyperluminous Hot dust obscured galaxies
The Astrophysical Journal, 2016Co-Authors: Lulu Fan, Yunkun Han, Robert Nikutta, Guillaume Drouart, K K KnudsenAbstract:We utilize a Bayesian approach to fit the observed mid-IR-To-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous Hot dust-obscured galaxies (Hot Dogs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot Dogs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot Dogs into torus and cold dust components. The main results are as follows. (1) Hot Dogs in our submillimeter-detected sample are hyperluminous , with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot Dogs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at , suggesting that the heating sources of Hot Dogs should be buried AGNs. (3) Hot Dogs have high dust temperatures ( K) and high IR luminosity of cold dust. The relation of Hot Dogs suggests that the increase in IR luminosity for Hot Dogs is mostly due to the increase of the dust temperature, rather than dust mass. Hot Dogs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot Dogs can be expected by their relatively high dust temperatures. (4) Hot Dogs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot Dogs by employing a physical model of galaxy evolution. This result suggests that Hot Dogs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolutions of massive galaxies, transforming them from the dusty starburst-dominated phase to the optically bright QSO phase.
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infrared spectral energy distribution decomposition of wise selected hyperluminous Hot dust obscured galaxies
arXiv: Astrophysics of Galaxies, 2016Co-Authors: Lulu Fan, Yunkun Han, Robert Nikutta, Guillaume Drouart, K K KnudsenAbstract:We utilize a Bayesian approach to fit the observed mid-IR-to-submm/mm spectral energy distributions (SEDs) of 22 WISE-selected and submm-detected, hyperluminous Hot dust-obscured galaxies. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot Dogs into torus and cold dust components. The main results are: 1) Hot Dogs in our submm-detected sample are hyperluminous, with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, averagely contributing ~24% of total IR luminosity. 2) Compared to QSO and starburst SED templates, the median SED of Hot Dogs shows the highest luminosity ratio between mid-IR and submm at rest-frame, while it is very similar to that of QSOs at 10-50um suggesting that the heating sources of Hot Dogs should be buried AGNs. 3) Hot Dogs have both high dust temperatures ~73K and IR luminosity of cold dust. The T-L relation of Hot Dogs suggests that the increase in IR luminosity for Hot Dogs is mostly due to the increase of the dust temperature, rather than dust mass. Hot Dogs have lower dust masses than those of submillimeter galaxies (SMGs) and QSOs within the similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot Dogs can be expected by their relatively high dust temperatures. 4) Hot Dogs have high dust covering factors, which deviate the previously proposed trend of the dust covering factor decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot Dogs by employing a physical model of galaxy evolution. The result suggests that Hot Dogs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst dominated phase to the optically bright QSO phase. (abridged)
Andrew Blackmore - One of the best experts on this subject based on the ideXlab platform.
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Hot Dogs hungry bears and wolves running out of mountain international wildlife law and the effects of climate change on large carnivores
Social Science Research Network, 2020Co-Authors: Arie Trouwborst, Andrew BlackmoreAbstract:The world’s largest predators, like their prey species and biodiversity at large, face increasing impacts from climate change, in addition to various other threats. Such climate impacts include the shrinking and disruption of habitat (e.g., polar bear, wolverine); range shifts, especially upslope (e.g., snow leopard, Ethiopian wolf) and poleward (e.g., golden jackal); reduced availability of key resources as water becomes scarcer and prey populations suffer from extreme weather, disease or other climate-related impacts (e.g., Gobi bear, cheetah); and increased human–wildlife conflict, when large carnivores progressively range beyond protected areas (e.g., African wild dog), or when climate change makes their ranges more suitable for livestock (e.g., lion). The aforementioned and many other large carnivore species are protected under global and/ or regional legal instruments for wildlife conservation, such as the Bonn Convention on Migratory Species (CMS), the Algiers and Maputo Conventions on African Nature Conservation, and the Bern Convention on European Wildlife Conservation. We view current international wildlife law through the lens of the aforementioned scenarios and, as it were, through the eyes of the wildlife species involved, and attempt to assess to what extent the law is ‘climate change proof’ in terms of being prepared for said scenarios. Our analysis indicates, first, that most of the climate adaptation measures that seem necessary— concerning protected areas, connectivity, counteracting climate impacts, and addressing non-climate threats—can in principle be achieved by fully and properly implementing the law as it stands. Second, it appears that the facilitation of range shifts beyond historic ranges still calls for some serious attention and resourceful interpretation. Third, it seems that particularly significant hurdles have yet to be overcome before the law is properly attuned to facilitating managed relocation (assisted colonization) where necessary.
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Hot Dogs hungry bears and wolves running out of mountain international wildlife law and the effects of climate change on large carnivores
Journal of International Wildlife Law & Policy, 2020Co-Authors: Arie Trouwborst, Andrew BlackmoreAbstract:The world’s largest predators, like their prey species and biodiversity at large, face increasing impacts from climate change, in addition to various other threats. Such climate impacts include the...
K K Knudsen - One of the best experts on this subject based on the ideXlab platform.
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infrared spectral energy distribution decomposition of wise selected hyperluminous Hot dust obscured galaxies
The Astrophysical Journal, 2016Co-Authors: Lulu Fan, Yunkun Han, Robert Nikutta, Guillaume Drouart, K K KnudsenAbstract:We utilize a Bayesian approach to fit the observed mid-IR-To-submillimeter/millimeter spectral energy distributions (SEDs) of 22 WISE-selected and submillimeter-detected, hyperluminous Hot dust-obscured galaxies (Hot Dogs), with spectroscopic redshift ranging from 1.7 to 4.6. We compare the Bayesian evidence of a torus plusgraybody (Torus+GB) model with that of a torus-only (Torus) model and find that the Torus+GB model has higher Bayesian evidence for all 22 Hot Dogs than the torus-only model, which presents strong evidence in favor of the Torus+GB model. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot Dogs into torus and cold dust components. The main results are as follows. (1) Hot Dogs in our submillimeter-detected sample are hyperluminous , with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, contributing on average of total IR luminosity. (2) Compared to QSO and starburst SED templates, the median SED of Hot Dogs shows the highest luminosity ratio between mid-IR and submillimeter at rest frame, while it is very similar to that of QSOs at , suggesting that the heating sources of Hot Dogs should be buried AGNs. (3) Hot Dogs have high dust temperatures ( K) and high IR luminosity of cold dust. The relation of Hot Dogs suggests that the increase in IR luminosity for Hot Dogs is mostly due to the increase of the dust temperature, rather than dust mass. Hot Dogs have lower dust masses than submillimeter galaxies (SMGs) and QSOs within a similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot Dogs can be expected by their relatively high dust temperatures. (4) Hot Dogs have high dust-covering factors (CFs), which deviate from the previously proposed trend of the dust CF decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot Dogs by employing a physical model of galaxy evolution. This result suggests that Hot Dogs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolutions of massive galaxies, transforming them from the dusty starburst-dominated phase to the optically bright QSO phase.
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infrared spectral energy distribution decomposition of wise selected hyperluminous Hot dust obscured galaxies
arXiv: Astrophysics of Galaxies, 2016Co-Authors: Lulu Fan, Yunkun Han, Robert Nikutta, Guillaume Drouart, K K KnudsenAbstract:We utilize a Bayesian approach to fit the observed mid-IR-to-submm/mm spectral energy distributions (SEDs) of 22 WISE-selected and submm-detected, hyperluminous Hot dust-obscured galaxies. By adopting the Torus+GB model, we decompose the observed IR SEDs of Hot Dogs into torus and cold dust components. The main results are: 1) Hot Dogs in our submm-detected sample are hyperluminous, with torus emission dominating the IR energy output. However, cold dust emission is non-negligible, averagely contributing ~24% of total IR luminosity. 2) Compared to QSO and starburst SED templates, the median SED of Hot Dogs shows the highest luminosity ratio between mid-IR and submm at rest-frame, while it is very similar to that of QSOs at 10-50um suggesting that the heating sources of Hot Dogs should be buried AGNs. 3) Hot Dogs have both high dust temperatures ~73K and IR luminosity of cold dust. The T-L relation of Hot Dogs suggests that the increase in IR luminosity for Hot Dogs is mostly due to the increase of the dust temperature, rather than dust mass. Hot Dogs have lower dust masses than those of submillimeter galaxies (SMGs) and QSOs within the similar redshift range. Both high IR luminosity of cold dust and relatively low dust mass in Hot Dogs can be expected by their relatively high dust temperatures. 4) Hot Dogs have high dust covering factors, which deviate the previously proposed trend of the dust covering factor decreasing with increasing bolometric luminosity. Finally, we can reproduce the observed properties in Hot Dogs by employing a physical model of galaxy evolution. The result suggests that Hot Dogs may lie at or close to peaks of both star formation and black hole growth histories, and represent a transit phase during the evolution of massive galaxies, transforming from the dusty starburst dominated phase to the optically bright QSO phase. (abridged)