59 research outputs found
Energy allocation trade-offs as a function of age in fungiid corals
To compete effectively, living organisms must adjust the allocation of available energy resources for growth, survival, maintenance, and reproduction throughout their life histories. Energy demands and allocations change throughout the life history of an organism, and understanding their energy allocation strategies requires determination of the relative age of individuals. As most scleractinian corals are colonial, the relationship between age and mass/size is complicated by colony fragmentation, partial mortality, and asexual reproduction. To overcome these limitations, solitary mushroom corals, Herpolitha limax from Okinawa, Japan and Fungia fungites from Okinawa and the Great Barrier Reef (GBR), Australia, were used to investigate how energy allocation between these fundamental processes varies as a function of age. Measurements of the relative growth, biochemical profiles, fecundity of individuals of different sizes, and the settlement success of their progeny have revealed physiological trade-offs between growth and reproduction, with increasing body mass ultimately leading to senescence. The importance of energy allocation for reproduction led us to examine the reproductive strategies and sex allocation in the two studied species. In the present study, the smallest individuals of both species studied were found to invest most of their energy in relative growth, showing higher lipid and carbohydrate content than the later stages. In medium-sized corals, this pattern was overturned in favour of reproduction, manifesting in terms of both the highest fecundity and settlement success of the resulting brooded larvae. Finally, a phase of apparent senescence was observed in the largest individuals, characterized by a decrease in most of the parameters measured. In addition, complex reproductive plasticity has been revealed in F. fungites in the GBR, with individual females releasing eggs, embryos, planulae, or a combination of these. These data provide the most direct estimates currently available for physiological, age-related trade-offs during the life history of a coral. The unusual reproductive characteristics of the GBR F. fungites indicate previously unknown layers of complexity in the reproductive biology of corals and have implications for their adaptive potential across a wide geographical scale
Diasporic Security and Jewish Identity
This paper explores the relationship between identity and security through an investigation into Jewish diasporic identity. The paper argues that the convention of treating identity as an objective referent of security is problematic, as the Jewish diaspora experience demonstrates. The paper presents a new way of conceptualizing identity and security by introducing the concept of diasporic security. Diasporic security reflects the geographical experience of being a member of a trans-state community, of having a fluid identity that is shaped by sometimes contradictory discourses emanating from a community that resides both at home and abroad. In introducing the concept of diasporic security, the paper makes use of literature in Diaspora Studies, Security Studies, recent works in contemporary political theory and sociology, and Woody Allen's film, Deconstructing Harry (1997)
The scientific payload of the Ultraviolet Transient Astronomy Satellite (ULTRASAT)
The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is a space-borne
near UV telescope with an unprecedented large field of view (200 sq. deg.). The
mission, led by the Weizmann Institute of Science and the Israel Space Agency
in collaboration with DESY (Helmholtz association, Germany) and NASA (USA), is
fully funded and expected to be launched to a geostationary transfer orbit in
Q2/3 of 2025. With a grasp 300 times larger than GALEX, the most sensitive UV
satellite to date, ULTRASAT will revolutionize our understanding of the hot
transient universe, as well as of flaring galactic sources. We describe the
mission payload, the optical design and the choice of materials allowing us to
achieve a point spread function of ~10arcsec across the FoV, and the detector
assembly. We detail the mitigation techniques implemented to suppress
out-of-band flux and reduce stray light, detector properties including measured
quantum efficiency of scout (prototype) detectors, and expected performance
(limiting magnitude) for various objects.Comment: Presented in the SPIE Astronomical Telescopes + Instrumentation 202
Biogeography, reproductive biology and phylogenetic divergence within the Fungiidae (mushroom corals)
While the escalating impacts of climate change and other anthropogenic pressures on coral reefs are well documented at the coral community level, studies of species-specific trends are less common, owing mostly to the difficulties and uncertainties in delineating coral species. It has also become clear that traditional coral taxonomy based largely on skeletal macromorphology has underestimated the diversity of many coral families. Here, we use targeted enrichment methods to sequence 2476 ultraconserved elements (UCEs) and exonic loci to investigate the relationship between populations of Fungia fungites from Okinawa, Japan, where this species reproduces by brooding (i.e., internal fertilization), and Papua New Guinea and Australia, where it reproduces by broadcast-spawning (i.e., external fertilization). Moreover, we analyzed the relationships between populations of additional fungiid species (Herpolitha limax and Ctenactis spp.) that reproduce only by broadcast-spawning. Our phylogenetic and species delimitation analyses reveal strong biogeographic structuring in both F. fungites and Herpolitha limax, consistent with cryptic speciation in Okinawa in both species and additionally for H. limax in the Red Sea. By combining UCE/exon data and mitochondrial sequences captured in off-target reads, we reinforce earlier findings that Ctenactis, a genus consisting of three nominal morphospecies, is not a natural group. Our results highlight the need for taxonomic and systematic re-evaluations of some species and genera within the family Fungiidae. This work demonstrates that sequence data generated by the application of targeted capture methods can provide objective criteria by which we can test phylogenetic hypotheses based on morphological and/or life history traits
Suggesting Friends Using the Implicit Social Graph
Although users of online communication tools rarely categorize their contacts into groups such as âfamilyâ, âco-workersâ, or âjogging buddiesâ, they nonetheless implicitly cluster contacts, by virtue of their interactions with them, forming implicit groups. In this paper, we describe the implicit social graph which is formed by users â interactions with contacts and groups of contacts, and which is distinct from explicit social graphs in which users explicitly add other individuals as their âfriendsâ. We introduce an interaction-based metric for estimating a userâs affinity to his contacts and groups. We then describe a novel friend suggestion algorithm that uses a userâs implicit social graph to generate a friend group, given a small seed set of contacts which the user has already labeled as friends. We show experimental results that demonstrate the importance of both implicit group relationships and interaction-based affinity ranking in suggesting friends. Finally, we discuss two applications of the Friend Suggest algorithm that have been released as Gmail Labs features
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