22 research outputs found
A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Iron Acquisition in Bacillus cereus: The Roles of IlsA and Bacillibactin in Exogenous Ferritin Iron Mobilization
No full textIn host-pathogen interactions, the struggle for iron may have major consequences on the outcome of the disease. To overcome the low solubility and bio-availability of iron, bacteria have evolved multiple systems to acquire iron from various sources such as heme, hemoglobin and ferritin. The molecular basis of iron acquisition from heme and hemoglobin have been extensively studied; however, very little is known about iron acquisition from host ferritin, a 24-mer nanocage protein able to store thousands of iron atoms within its cavity. In the human opportunistic pathogen Bacillus cereus, a surface protein named IlsA (Iron-regulated leucine rich surface protein type A) binds heme, hemoglobin and ferritin in vitro and is involved in virulence. Here, we demonstrate that IlsA acts as a ferritin receptor causing ferritin aggregation on the bacterial surface. Isothermal titration calorimetry data indicate that IlsA binds several types of ferritins through direct interaction with the shell subunits. UV-vis kinetic data show a significant enhancement of iron release from ferritin in the presence of IlsA indicating for the first time that a bacterial protein might alter the stability of the ferritin iron core. Disruption of the siderophore bacillibactin production drastically reduces the ability of B. cereus to utilize ferritin for growth and results in attenuated bacterial virulence in insects. We propose a new model of iron acquisition in B. cereus that involves the binding of IlsA to host ferritin followed by siderophore assisted iron uptake. Our results highlight a possible interplay between a surface protein and a siderophore and provide new insights into host adaptation of B. cereus and general bacterial pathogenesis. Author Summary Iron homeostasis is important for all living organisms; too much iron confers cell toxicity, and too little iron results in reduced cell fitness. While crucial for many cellular processes in both man and pathogens, a battle for this essential nutrient erupts during infection between the host and the invading bacteria. Iron is principally stored in ferritin, a large molecule able to bind several thousand iron ions. Although host ferritins represent a mine of iron for pathogens, studies of the mechanisms involved in its acquisition by bacteria are scarce. In the human opportunistic pathogen Bacillus cereus, the surface protein IlsA is able to bind several host iron sources in vitro. In this study, we show that IlsA acts as a ferritin receptor and enhances iron release from the ferritin through direct interaction with each ferritin subunit. Moreover, we demonstrate that the siderophore bacillibactin, a small secreted iron chelator, is essential for ferritin iron acquisition and takes part in B. cereus virulence. We propose a new iron acquisition model that provides new insights into bacterial host adaptation
Understanding Ocean Acidification Impacts on Organismal to Ecological Scales
No full textOcean acidification (OA) research seeks to understand how marine ecosystems and global elemental cycles will respond to changes in seawater carbonate chemistry in combination with other environmental perturbations such as warming, eutrophication, and deoxygenation. Here, we discuss the effectiveness and limitations of current research approaches used to address this goal. A diverse combination of approaches is essential to decipher the consequences of OA to marine organisms, communities, and ecosystems. Consequently, the benefits and limitations of each approach must be considered carefully. Major research challenges involve experimentally addressing the effects of OA in the context of large natural variability in seawater carbonate system parameters and other interactive variables, integrating the results from different research approaches, and scaling results across different temporal and spatial scales
A classical problem in linear regression or how to estimate the mean of a univariate normal distribution with known variance
No full textEffects of EMFs from Undersea Power Cables on Elasmobranchs and Other Marine Species.
No full textAnthropogenic electromagnetic fields (EMFs) have been introduced into the marine environmentaround the world and from a wide variety of sources for well over a century. Despite this, littleis known about potential ecological impacts from EMFs. For decades, power transmissioncables have been installed across bays and river mouths, and connecting near-shore islands to themainland, with little consideration of possible effects to marine species from EMFs. At a time ofgreater environmental awareness, the US now faces the possibility of a new source of EMFs overa much greater extent of the seabed from offshore renewable energy facilities in coastal waters.This literature review synthesizes information on the types of power cables and models theexpected EMFs from representative cables. Available information on electro- and magnetosensitivityof marine organisms, including elasmobranchs (sharks and rays) and other fishspecies, marine mammals, sea turtles, and invertebrates is summarized and used in conjunctionwith the power cable modeling results to evaluate the level of confidence the existing state ofknowledge provides for impact assessment. Gaps in our knowledge of power cablecharacteristics and the biology needed to understand and predict impacts are summarized andform the basis of recommendations for future research priorities. Potential mitigationopportunities are described with a discussion of their potential secondary impacts as well assuggested methods for monitoring mitigation effectiveness. Finally, because interest in offshorerenewable energy has increased throughout US coastal waters, there is a concern that organismscould be exposed to multiple seabed power cables. Cumulative effects of this exposure are discussed
Policy Space to Prevent and Mitigate Financial Crises in Trade and Investment Agreements
No full textDo nations have the policy space to deploy capital controls in order to prevent and mitigate financial crises? This paper examines the extent to which measures to mitigate this crisis and prevent future crises are permissible under a variety of bilateral, regional and multilateral trade and investment agreements. It is found that the United States trade and investment agreements, and to a lesser extent the WTO, leave little room to manoeuvre when it comes to capital controls. This is the case despite the increasing economic evidence showing that certain capital controls can be useful in preventing or mitigating financial crises. It also stands in contrast with investment rules under the IMF, OECD and the treaties of most capital exporting nations which allow for at least the temporary use of capital controls as a safeguard measure. Drawing on the comparative analysis conducted in the paper, the author offers a range of policies that could be deployed to make the United States investment rules more consistent with the rules of its peers and the economic realities of the 21st century.
Kyoto and the COPs: Lessons Learned and Looking Ahead
No full textThis is the post-refereed, pre-print version of this article. The published version of this article is published by Brill (Martinus Nijhoff) in Hague Yearbook of International Law vol. 23, ISBN 9789004206809, pp. 17-90.This article argues that the Kyoto Protocol to the 1992 Framework Convention on Climate Change (UNFCCC) was doomed to fail ab initio because it systematically misunderstood the nature of climate change as a policy issue between 1985 and 2009. It explains why this is the case by analyzing the Kyoto Protocol’s shortcomings and deficiencies. Moving the climate change agenda forward multilaterally among the 195 parties to the UNFCCC is proving to be a serious challenge. The lack of progress in UNFCCC negotiations in recent years, especially the failure to obtain an international agreement on emissions limitations targets and timetables by all major developed and developing country emitters, has led many to question whether the UNFCCC is, in fact, the best and most effective forum for mobilizing a global response to climate change. The current approach to negotiating a comprehensive, universal, and legally binding global agreement on climate change is unlikely to succeed. The near-disaster 2009 Conference of the Parties-15 in Copenhagen empirically demonstrated that the UN machinery is incapable of moving forward fast enough to produce a global climate deal. Moreover, international climate policy, as it has been understood and practiced by many governments of the world under the Kyoto Protocol approach, has failed to produce any discernable real world reductions in emissions of greenhouse gases since the mid 1990s. Part 2 is devoted to the main legal, structural, and policy responses to climate change by providing an analysis of most Conferences of the Parties. Part 3 provides then an analysis of the Kyoto Protocol. Part 4 then analyzes the position of the three main players in climate change: the U.S., China, and the European Union. The article concludes with some recommendations for the future
Relationships between psychosocial stress, cortisol, apolipoprotein є4, beta-amyloid, hippocampal volumes and Alzheimer's disease in a sample of South African older adults
No full textIncludes bibliographical references.Many factors contribute to age-related changes in cognitive functioning. There is no single defined profile of factors that is clearly associated with the presence, or rate of progression, of cognitive changes in older adults. Stress, both psychosocial and physiological, may play a role. Aims: The general aim of this study was to explore the relationships between cognitive functioning and cognitive decline, on the one hand, and psychosocial and physiological stress, as well as a range of sociodemographic, psychosocial and physiological factors, on the other, in older adults with a range of cognitive function including healthy and impaired. Methods: Both cross-sectional (Study 1) and longitudinal (Study 2) designs addressed these aims. Study 1 examined the contribution of stress and sociodemographic, psychosocial, and physiological factors to cognition. Participants were 69 cognitively healthy older adults and 65 possible or probable Alzheimer’s disease (AD) patients. They were all over the age of 60 and resided in the greater Cape Town metropolitan region of South Africa. Cognitive functioning was assessed using a battery of neuropsychological tests. Salivary cortisol levels, apolipoprotein E (APOE) genotype, and plasma beta-amyloid levels were determined at baseline
Bairdiella ronchus
No full textBairdiella ronchus (Cuvier, 1830) (Fig. 4b, c, Tables 4, 5) Corvina ronchus Cuvier, 1830:107 (Lake Maracaibo, Venezuela; Dominican Republic; Cuba; Suriname MNHN 0095 (1) Dominican Republic, MNHN 5345 (2) Suriname, MNHN 7634 (1, dry) Maracaibo, MNHN 7637 (1), MNHN A–5543 (1) Martinique.–Günther, 1860: 299 (Catalogue of the Fishes in the British Museum). Sciaena bedoti Regan, 1905:391, Pl. 6 (fig. 1) (Cuba. Syntypes: BMNH 1905.3.18.2 [ex MHNG] (1), MHNG 678.01 (1)). Bairdiella ronchus Poey, 1868: 324 (fishes of Cuba; synopsis).– Jordan, Eigenmann, 1889: 388 (review of sciaenids from America and Europe).– Jordan, Evermann, 1898: 1436 (in part; description and synonymy).– Meek, Hildebrand, 1925: 634– 635 (fishes of Panama; description; in part).– Mago-Leccia, 1965: 309 (rio Unare, Venezuela; listed).– Chao, 1978:39 (in part, redescription).– Cervigón, 1992: 398 (in part, fishes of Venezuela; listed).– Cervigón, 1993:242 (in part, fishes of Venezuela; listed).– Greenfield, Thomerson, 1997:182 (fishes of Belize; listed).– González Bencomo et al., 1997:159 (fishes of Maracaibo, Venezuela; listed).– Aguilera, 1998:50 (fishes of Occidental Venezuela; listed).– Marín, 2000:75 (fishes of Unare Lagoon, Venezuela; short description).– Smith et al., 2003:37 (fishes of Pelican Cays, Belize; listed).– Matamoros et al., 2009:19 (fishes of Honduras; listed).– Angulo et al., 2013:1002 (checklist of fishes from Costa Rica). Diagnosis. Bairdiella ronchus is distinct from B. armata (EP), which occurs between the Gulf of California and Co- lombia (EP), by the presence of 50-53 scales with pores on the lateral line, rarely 49 (vs. 46-49, Tab. 5a); from B. chrysoura (WA), which is found between Cape Cod (US) and the western Gulf of Mexico, by the presence of five pores on the chin (vs. six), and a very robust second anal-fin spine, as long as the first anal-fin ray (vs. thin second anal-fin spine, shorter than first anal-fin ray, Fig. 4b,c); from B. goeldi sp. nov., which is found on the Brazilian coast, by having an orbital diameter less than 8% SL (vs. more than 8% SL, Fig. 5a), and orbital diameter 2.4-3.8 times the caudal peduncle length (vs. 1.6-2.3, rarely more than 2.3, Fig. 5b); from B. ensifera (EP), which is found between Mexico and Peru (EP), by having wavy stripes or dark spots on the body (vs. body silvery without stripes or spots, Fig. 4b,c); from B. icistia (EP), which is found between the Gulf of California and Guatemala (EP), by the presence of 22-24 rays in the dorsal fin (vs. 25-29, Tab. 5d), 22-24 gill rakers on the first bran- chial arch, rarely more than 24 (vs. 25-27, Tab. 5f), and the lack of a dark spot at the base of the pectoral fins (vs. with dark spot at the base of the pectoral fins, Fig. 4b,c); from B. veraecrucis (WA), which occurs between Florida (US) and the northern Gulf of Mexico, by having a relatively larger head and dorsal fin relatively shorter (Tab. 4), with dorsal fin length 1.6-2.5 times in the head length (vs. 1.2-1.5, Fig. 5c), and dorsal fin length 1.7-2.7 times in the head depth (vs. 1.2-1.5, Fig. 5d). Molecular diagnosis. The haplotypes of B. ronchus differed by three bases from of all the other Atlantic species analyzed, by nine bases from B. goeldi sp. nov., by 17 bases from B. veraecrucis, and by 97 bases from B. chrysoura (Tab. 3), with genetic distances of 0.018±0.005 from B. goeldi sp. nov., 0.030±0.007 from B. veraecrucis, and 0.183±0.019 from B. chrysoura (Tab. 2). Description. Morphometric and meristic data are presen- ted in Tabs. 4, 5. D. X +I. 22-24; A.II.8; P. 16-18; gill rakers 22-26; pored lateral line scales to caudal fin base 49-53±; scale rows above lateral line 8-9 (rarely 10), below 9-11. Body moderately long and compressed, maximum depth at origin of dorsal fin. Dorsal profile straight, ascending un- til dorsal fin origin, posteriorly convex until caudal pedun- cle, especially in larger specimens. Ventral profile flattened from pelvic fin to anal fin origin. Head relatively long, high. Snout blunt in lateral view, dorsal profile naked. Mouth ter- minal, barely inclined; posteriorrmost tip of premaxillary bone passing vertical through middle of orbit. Teeth conical, premaxilla with three or four rows, external row with enlar- ged teeth; dentary with one row. Orbit lateral, eyes round, moderately large, orbital diameter approximately equal to snout length. Interorbital space larger than orbital diameter, slightly convex, covered with ctenoid scales (cycloid ante- riorly). Nostrils visible with naked eye, anterior nostril oval, posterior nostril larger and teardrop like, close to anterior eye margin, over or nearly above horizontal line through middle of orbit. Lateral sensory canals on head visible on infraorbital, dentary and preopercle; five ventral pores on dentary, one central, triangular and subequal in size, and two pores on each side. Preopercle margin serrated, with about 12-15 spines, two or three at angle largest. Opercle tip an- gled, slightly anterior to vertical through pectoral fin base. Gill rakers well developed. Scales ctenoid on trunk, belly, pectoral fin base, opercle, preopercle, infraorbital (ventral most two rows) and interorbital region, especially in spe- cimens larger than 150 mm SL; cycloid on infraorbital (an- teriorly), preorbital region below nostrils, opercle and inte- robital in specimens smaller than 150 mm SL. Lateral line simple, arched above the pectoral fin to middle of second dorsal fin, straight elsewhere. First dorsal fin without sca- les, membranes of second dorsal fin and anal fin with one or two rows of 5-7 small cycloid scales. Base of pectoral fin covered with cycloid scales, extending to proximal third in largest specimens. Caudal fin base covered with a cluster of small cycloid scales, rows of cycloid scales on caudal-fin rays, nearly three quarters of their length. Spinous dorsal fin short, first spine shortest, spines IV-V longest, with small notch between first and second dorsal fin. Origin of second dorsal fin posterior to vertical through pectoral fin tip, with second dorsal soft rays shorter than the longest first dorsal- -fin spines. Pectoral fin falcate and relatively short, its length approximately equal to the second anal spine length. Pelvic fin origin behind vertical though pectoral fin base. Anal fin emarginated, second anal-fin spine very stout and longer than remaining spines. Caudal peduncle depth slightly lar- ger than eye diameter, 10.4-11.9% SL, length 18.2-22.2% SL; caudal fin truncated to slightly rhomboidal, central rays longest. Color in alcohol. Dusky blue in the dorsal portion above lateral line and on the top of the head, silver below lateral line, with bands of pigments on the flanks, oblique at the top and more or less parallel below lateral line. The dorsal, anal and caudal fins are dusky, pelvic fins are yellowish, and the pectoral fins are yellowish only at their bases. Distribution and habitat. Greater Caribbean Central Province, Central America, West Indies, Bermuda, and Vene- zuela (Fig. 3). Remarks. In a comprehensive review of the genus Bairdiella, Chao (1978), following previous authors, synony- mized Bairdiella armata Gill, 1863, Corvina subaequalis Poey, 1875, Corvina fulgens Vaillant & Bocourt, 1883, Bairdiella veraecrucis, and Sciaena (Bairdiella) bedoti Regan, 1905 without examining the type specimens or listing the material examined. As result, B. ronchus was considered to be widely distributed in the western Atlantic, from North Carolina to southern Brazil (Cervigón, 1992; McEachran, Fechhelm, 2003, see comments on B. goeldi sp. nov., above). Here, Bairdiella ronchus is redefined based on morphologi- cal (Fig. 1) and molecular evidence (Fig. 2, Tabs. 2, 3), and its distribution is restricted to the Greater Caribbean Central Province, between Cuba and Venezuela. As Venezuela is one of the type localities of the species, MHNH 7634, collected from Lake Maracaibo, Venezuela, is recognized as the lecto- type of the present designation. The recognition of Corvina fulgens Vaillant & Bocourt, 1883 as a junior synonym of B. ronchus by Chao (1978) is erroneous, given that Vaillant, Bocourt (1883) described C. fulgens based on two specimens collected at La Union, El Salvador, in the eastern Pacific, during a scientific expedition to Mexico and Central America. Furthermore, the original description of C. fulgens includes an error in the scale count (115/8/5 scales above, on and below the lateral line, respec- tively; Vaillant, Bocourt, 1883: p. 164). The authors provide the correct count (11/58/15) when subsequently comparing the new species to Corvina macrops Steindachner, 1876, commenting that “This species appears to be approaching the Corvina macrops, […] But the latter fish is higher […] Of the scales, in particular for the transverse line, also differs, 7/60/11 instead of 11/58/15” (p. 165). Further examination of the syntypes of C. fulgens (MNHH A-0975) revealed that they have 23 soft rays in the second dorsal fin, and less than 55 sca- les in the lateral line to the caudal fin base. C. fulgens is therefore regarded as a junior synonym of B. armata Gill, 1863. Corvina subaequalis Poey, 1875 was described from a 245 mm TL specimen collected in Cuba. The author in- dicated that this specimen was sent to the Berlin Museum (ZMB), but it was not cataloged and is presumably lost. The holotype of C. subaequalis was not illustrated, and the des- cription of this species is not accurate enough to differentiate it from several western Atlantic sciaenids. Despite those situations, Chao (1978) considered C. subaequalis to be a junior synonym of B. ronchus, without providing arguments for that decision. Some of the information in Poey’s des- cription is discrepant from the characteristics observed in specimens of B. ronchus, such as the presence of fine den- ticulations in the preopercle (p. 59) vs. moderately largely serrated in all specimens of Bairdiella we examined, and the presence of 25 soft rays in the dorsal fin (vs. 21-24 soft rays), which may be attributable to individual variation, ontogeny or differences in counting the last two conjoined dorsal and anal fin rays as one element or not. However, as images of the holotype of C. subaequalis are not available and the type specimen is probably lost, the exact affiliation of this taxon with B. ronchus cannot be ascertained. Therefore, C. subaequalis should be regarded as nomen dubium. Material examined. LBP 6080, 2, 135- 136 mm SL, Venezuela, Ilsa de Margarita, mouth of Rio Nova Esparta, Isla de Margarita; LBP 6436, 2, 92-94 mm SL, Venezuela, Isla de Margarita, mouth of Rio Nova Esparta; USNM 4704, 1, 106 mm SL, Cuba; USNM 32090, 1, 209 mm SL, Cuba; USNM 44185, 1, 119 mm SL, Nicaragua, Greytown; USNM 81164, 1, 114 mm SL, Panama, Mindi Cut; USNM 80710, 1, 185 mm SL, Panama, Mindi Reef; USNM 80711, 1, 130 mm SL, Panama, Mindi Cut; USNM 81165, 1, 109 mm SL, Panama, Mindi Cut; USNM 80708, 1, 151 mm SL, Panama, Colon market; USNM 81166, 1, 79 mm SL, Panama, Portobelo; USNM 81168, 2, 87-97 mm SL, Panama, Cristobal; USNM 114303, 1, 203 mm SL, Guatemala, Laguna Grande; USNM 121746, 2, 90-98 mm SL, Venezuela, Cano de Agua; USNM 133714, 2, 192- 241 mm SL, Haiti; USNM 178227, 2, 138- 168 mm SL, Haiti; USNM 300471, 3, 136- 160 mm SL, Belize, east of Dangriga; USNM 343624, 1, 100 mm SL, Cuba, Cayo Mendoza, Cuba.Published as part of Marceniuk, Alexandre Pires, Molina, Eduardo Garcia, Caires, Rodrigo Antunes, Rotundo, Matheus Marcos, Wosiacki, Wolmar Benjamin & Oliveira, Claudio, 2019, Revision of Bairdiella (Sciaenidae: Perciformes) from the western South Atlantic, with insights into its diversity and biogeography, pp. 1-18 in Neotropical Ichthyology 17 (1) on pages 12-14, DOI: 10.1590/1982-0224-20180024, http://zenodo.org/record/364946
