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The Asian fish tapeworm, Schyzocotyle acheilognathi (syn. Bothriocephalus acheilognathi) represents a threat to freshwater fish, mainly cyprinids, across the globe. This tapeworm possesses an extraordinary ability to adapt to different environmental conditions and, because of that, from its natural geographical origin in mainland Asia, it has colonized every continent except Antarctica. It is thought that this pathogenic tapeworm was first co-introduced into Mexico in 1965 from China, with the grass carp Ctenopharyngodon idella, although the first formal record of its presence was published in 1981. Over the past 35 years, the Asian fish tapeworm has invaded about 22% of the freshwater fish in Mexico. Because fish communities in Mexico are characterized by high species richness and levels of endemism, S. acheilognathi is considered as a co-introduced and co-invasive species. In this review, we update the geographic distribution and host spectrum of the Asian fish tapeworm in Mexico. Up until December 2016, the tapeworm had been recorded in 110 freshwater fish species (96 native and 14 introduced), included in 51 genera, 11 families and 4 orders; it was also widely distributed in all types of aquatic environments, and has been found in 214 localities. We present novel data from a survey aimed at establishing the distribution pattern of the tapeworm in native freshwater fishes of two rivers in north-central Mexico, and the genetic variation among individuals of this co-invasive species collected from different host species and localities. We discuss briefly the factors that have determined the remarkable invasive success of this parasite in freshwater systems in Mexico.
Commercial aluminum alloys corresponding to Al-Cu-Si family are commonly used in casting and molding process because their high castability. The main characteristics of these alloys are the excellent weight/strength relation in conjunction with wear and corrosion resistance. Additionally, the mechanical properties of these alloys could be enhanced by heat treatment.
In Al A319 alloys, Cu and Mg are the main responsible to increase the mechanical properties after T6 heat treatment due to the precipitation of Al2Cu and Mg2Si and Al2CuMg phase . Combined effects of Ni and Cu improve strength and hardness at relatively elevated temperature , Due to the low solubility of Ni in Al (0.04%), it has been reported the formation of FeAl9FeNi-type intermetallic, which is not totally dissolved with the typical solution treatments used in aluminum alloys . Hayajneh et al., found that increasing amounts of intermetallic compounds Al3Ni, Al3(CuNi)2 and Al7Cu4Ni in Al-Cu alloy, the hardness increase .
The effect of Ni addition and solution treatment time on the microstructure and hardness of the Al A319 alloy are studied by Vickers microhardness (VHN), Rockwell B hardness (HRB), X Ray Diffraction (XRD), Optical Microscopy (OM), Scanning Electron Microscopy (SEM).
We gathered a multiwavelength dataset of two well-known LBVs. We found a complex mass-loss, with evidence of variability, such as has been seen previously. In addition, our data reveal signatures of collimated stellar winds. We propose a new scenario for these two stars where the nebula shaping is influenced by the presence of a companion star and/or fast rotation.
We present a new estimate of the mass of the Milky Way, making use of a large sample of 955 field horizontal-branch (FHB) stars from the Early Data Release of the Sloan Digital Sky Survey. This sample of stars has been classified on the basis of an automated analysis approach, in combination with other methods, in order to obtain estimates of the physical parameters of the stars, i.e., Teff, log g, [Fe/H], and should be relatively free of contamination from halo blue stragglers. the stars all have measured radial velocities and photometric distance estimates, and the sample includes objects as distant as ~ 75 kpc from the Galactic center. Application of a Bayesian likelihood method, for a specific model of the Galaxy, indicates that the total mass of the Galaxy lies in the range 1.5 − 4.0 × 1012 M⊙. Our sample appears to reveal a clear signature of a dual halo population of FHB stars, with the boundary between the inner and outer halo around 20 kpc, and the possibility of rather striking differences in the rotational properties of the Galaxy at low metallicity.
The Miocene epoch was a time of major change in the East African Rift System (EARS) as forest habitats were transformed into grasslands and hominids appeared in the landscape. Here we provide new sedimentological and palynological data on the middle–upper Miocene Ngorora Formation (Tugen Hills, Central Kenya Rift, EARS), together with clay mineral characterizations, mammal finds and a description of the Ngorora fish Lagerstätte. Furthermore, we introduce a revised age of c. 13.3 Ma for the onset of the Ngorora Formation. The older part of the Ngorora Formation (c. 13.3–12 Ma) records low-energy settings of lakes, floodplains and palaeosols, and evidence of analcime indicates that lakes were alkaline. The palynomorph spectrum consists of tree pollen (Juniperus, Podocarpus), Euphorbiaceae pollen (Acalypha, Croton) and herbaceous pollen of Poaceae and Asteraceae, suggestive of wooded grasslands or grassy woodlands. Alkaline lakes, floodplains and palaeosols continue upsection (c. 12–9 Ma), but environmental fluctuations become more dynamic. Paucity of palynomorphs and the presence of an equid may point to progressively drier conditions. A total of about 500 articulated fish fossils were recovered from distinctive layers of almost all sections studied and represent different lineages of the Haplotilapiines (Pseudocrenilabrinae, Cichlidae). Some of the fish kills may be attributable to rapid water acidification and/or asphyxiation by episodic ash falls. Repeated instances of abrupt change in water depth in many sections are more likely to be due to synsedimentary tectonic activity of the Central Kenya Rift than to climatic variation. Overall, the preservation of the Ngorora fish Lagerstätte resulted from the interplay of tectonics, formation of alkaline lakes and explosive volcanism. As records of grasslands that pre-date late Miocene time are rare, our finding of middle Miocene (12–13 Ma) grassy savannah in the Central Kenya Rift is also relevant to models of human evolution in East Africa.
The ATP-binding cassette transporter G2/breast cancer resistance protein (ABCG2/BCRP) is an efflux protein involved in the bioavailability and milk secretion of endogenous and exogenous compounds, actively affecting milk composition. A limited number of physiological substrates have been identified. However, no studies have reported the specific effect of this polymorphism on the secretion into milk of compounds implicated in milk quality such as vitamins or endogenous compounds. The bovine ABCG2 Y581S polymorphism is described as a gain-of-function polymorphism that increases milk secretion and decreases plasma levels of its substrates. This work aims to study the impact of Y581S polymorphism on plasma disposition and milk secretion of compounds such as riboflavin (vitamin B2), enterolactone, a microbiota-derived metabolite from the dietary lignan secoisolariciresinol and uric acid. In vitro transport of these compounds was assessed in MDCK-II cells overexpressing the bovine ABCG2 (WT-bABCG2) and its Y581S variant (Y581S-bABCG2). Plasma and milk levels were obtained from Y/Y homozygous and Y/S heterozygous cows. The results show that riboflavin was more efficiently transported in vitro by the Y581S variant, although no differences were noted in vivo. Both uric acid and enterolactone were substrates in vitro of the bovine ABCG2 variants and were actively secreted into milk with a two-fold increase in the milk/plasma ratio for Y/S with respect to Y/Y cows. The in vitro ABCG2-mediated transport of the drug mitoxantrone, as a model substrate, was inhibited by enterolactone in both variants, suggesting the possible in vivo use of this enterolignan to reduce ABCG2-mediated milk drug transfer in cows. The Y581S variant was inhibited to a lesser extent probably due to its higher transport capacity. All these findings point to a significant role of the ABCG2 Y581S polymorphism in the milk disposition of enterolactone and the endogenous molecules riboflavin and uric acid, which could affect both milk quality and functionality.
Asexually proliferating Taenia crassiceps (Zeder, 1800) metacestodes isolated within past decades have been successfully sub-cultured under experimental conditions using Mus musculus Linnaeus, 1758 mice. However, during their development, morphological irregularities of scolex structures have been reported in two of the three strains of this cestode species maintained in mice – ORF and KBS. The main goal of this work is to describe the abnormalities observed in a sample of 118 cysticerci of the third T. crassiceps strain used at present – WFU. Morphological abnormalities were detected in 39.8% of the evaginated scoleces; they consisted of supernumerary suckers (n= 2), duplicated (n= 2) or absent rostellum (n= 1), as well as absent or aberrant (n= 29) hooks, which were significantly shorter when compared to the large and short hook lengths referred to in the literature.
Different from previous triennial reports, this report covers the activities of IAU Commission 36 ‘Theory of Stellar Atmospheres’ over the past six years†, and will be the last report from the ‘old’ Commission 36. After the General Assembly in Honolulu (August 2015), a new Commission ‘Stellar and Planetary Atmospheres’ (C.G5, under Division G, ‘Stars and Stellar Physics’) has come into life, and will continue our work devoted to the outer envelopes of stars, as well as extend it to the atmospheres of planets (see Sect. 4).