376 research outputs found
New directions in island biogeography
Aim: Much of our current understanding of ecological and evolutionary processes comes from island research. With the increasing availability of data on distributions and phylogenetic relationships and new analytical approaches to understanding the processes that shape species distributions and interactions, a re-evaluation of this ever-interesting topic is timely.
Location: Islands globally.
Methods: We start by arguing that the reasons why island research has achieved so much in the past also apply to the future. We then critically assess the current state of island biogeography, focusing on recent changes in emphasis, including research featured in this special issue of Global Ecology and Biogeography. Finally, we suggest promising themes for the future. We cover both ecological and evolutionary topics, although the greater emphasis on island ecology reflects our own backgrounds and interests.
Results: Much ecological theory has been directly or indirectly influenced by research on island biotas. Currently, island biogeography is renascent, with research focusing on, among other things, patterns and processes underlying species interaction networks, species coexistence and the assembly of island communities through ecological and evolutionary time. Continuing island research should provide additional insight into biological invasions and other impacts of human activities, functional diversity and ecosystem functioning, extinction and diversification, species pools and more. Deeper understanding of the similarities and differences between island and mainland systems will aid transferability of island theory to continental regions.
Main conclusions: As research in biogeography and related fields expands in new directions, islands continue to provide opportunities for developing insights, both as natural laboratories for ecology and evolution and because of the exceptions islands often present to the usual ‘rules’ of ecology. New data collection initiatives are needed on islands world-wide and should be directed towards filling gaps in our knowledge of within-island distributions of species, as well as the functional traits and phylogenetic relationships of island species
Detailed electronic structure studies on superconducting MgB and related compounds
In order to understand the unexpected superconducting behavior of MgB
compound we have made electronic structure calculations for MgB and closely
related systems. Our calculated Debye temperature from the elastic properties
indicate that the average phonon frequency is very large in MgB compared
with other superconducting intermetallics and the exceptionally high in
this material can be explained through BCS mechanism only if phonon softening
occurs or the phonon modes are highly anisotropic. We identified a
doubly-degenerate quasi-two dimensional key-energy band in the vicinity of
along -A direction of BZ which play an important role in
deciding the superconducting behavior of this material. Based on this result,
we have searched for similar kinds of electronic feature in a series of
isoelectronic compounds such as BeB, CaB, SrB, LiBC and
MgBC and found that MgBC is one potential material from the
superconductivity point of view. There are contradictory experimental results
regarding the anisotropy in the elastic properties of MgB ranging from
isotropic, moderately anisotropic to highly anisotropic. In order to settle
this issue we have calculated the single crystal elastic constants for MgB
by the accurate full-potential method and derived the directional dependent
linear compressibility, Young's modulus, shear modulus and relevant elastic
properties. We have observed large anisotropy in the elastic properties. Our
calculated polarized optical dielectric tensor shows highly anisotropic
behavior even though it possesses isotropic transport property. MgB
possesses a mixed bonding character and this has been verified from density of
states, charge density and crystal orbital Hamiltonian population analyses
Improvements in the determination of ISS Ca II K parameters
Measurements of the ionized Ca II K line are one of the major resources for
long-term studies of solar and stellar activity. They also play a critical role
in many studies related to solar irradiance variability, particularly as a
ground-based proxy to model the solar ultraviolet flux variation that may
influence the Earth's climate. Full disk images of the Sun in Ca II K have been
available from various observatories for more than 100 years and latter
synoptic Sun-as-a-star observations in Ca II K began in the early 1970s. One of
these instruments, the Integrated Sunlight Spectrometer (ISS) has been in
operation at Kitt Peak (Arizona) since late 2006. The ISS takes daily
observations of solar spectra in nine spectra bands, including the Ca II K and
H line s. We describe recent improvements in data reduction of Ca II K
observations, and present time variations of nine parameters derived from the
profile of this spectral line
Microbial Ecology of the Osiris-Rex Assembly Test and Launch Environment.
No abstract availabl
Genome-wide association analyses identify 13 new susceptibility loci for generalized vitiligo
We previously reported a genome-wide association study (GWAS) identifying 14 susceptibility loci for generalized vitiligo. We report here a second GWAS (450 individuals with vitiligo (cases) and 3,182 controls), an independent replication study (1,440 cases and 1,316 controls) and a meta-analysis (3,187 cases and 6,723 controls) identifying 13 additional vitiligo-associated loci. These include OCA2-HERC2 (combined P = 3.80 × 10 ), MC1R (P = 1.82 × 10 ), a region near TYR (P = 1.57 × 10 ), IFIH1 (P = 4.91 × 10 ), CD80 (P = 3.78 × 10 ), CLNK (P = 1.56 × 10 ), BACH2 (P = 2.53 × 10 ), SLA (P = 1.58 × 10 ), CASP7 (P = 3.56 × 10 ), CD44 (P = 1.78 × 10 ), IKZF4 (P = 2.75 × 10 ), SH2B3 (P = 3.54 × 10 ) and TOB2 (P = 6.81 × 10 ). Most vitiligo susceptibility loci encode immunoregulatory proteins or melanocyte components that likely mediate immune targeting and the relationships among vitiligo, melanoma, and eye, skin and hair coloration
Defining the 'Social' in 'Social Entrepreneurship': Altruism and Entrepreneurship
Abstract. What is social entrepreneurship? In, particular, what’s so social about it? Understanding what social entrepreneurship is enables researchers to study the phenomenon and policy-makers to design measures to encourage it. However, such an understanding is lacking partly because there is no universally accepted definition of entrepreneurship as yet. In this paper, we suggest a definition of social entrepreneurship that intuitively accords with what is generally accepted as entrepreneurship and that captures the way in which entrepreneurship may be altruistic. Based on this we provide a taxonomy of social entrepreneurship and identify a number of real cases from Asia illustrating the different forms it could take. Keywords: social entrepreneurship, definition, taxonomy, altruism Social entrepreneurship is a concept that has captured the imagination of many researchers and policy-makers in recent years. Social entrepreneurship suggests that entrepreneurship may be aimed at benefiting society rather than merely maximising individual profits. It appears to promise an altruistic form of capitalism that does not evaluate all human activities in business terms. It enables a bridge to be built between enterprise and benevolence (Roberts and Woods, 2005). The history of the term ‘social entrepreneurship ’ can be traced to the publication of a Demos thinktank report entitled The Rise of the Social Entrepreneur (Leadbeater, 1997) in the United Kingdom and probably a little earlier in the United States to the publication of New Social Entrepreneurs by the Roberts Foundation (Emerson and Twerksy, 1996). Prior to this, some of the activities under the rubric of social entrepreneurship were either termed ‘community development ’ or those in ‘social purpose organizations’. There is considerable use of the term in popular literature although academic literature on it is thin (Taylor, Hobbs, Nilsson, O’Halloran and Preisser, 2000). Recent interest saw a call for papers for a special issue on social entrepreneurship (Honig an
A heritable subset of the core rumen microbiome dictates dairy cow productivity and emissions
A 1000-cow study across four European countries was undertaken to understand to what extent ruminant microbiomes can be controlled by the host animal and to identify characteristics of the host rumen microbiome axis that determine productivity and methane emissions. A core rumen microbiome, phylogenetically linked and with a preserved hierarchical structure, was identified. A 39-member subset of the core formed hubs in co-occurrence networks linking microbiome structure to host genetics and phenotype (methane emissions, rumen and blood metabolites, and milk production efficiency). These phenotypes can be predicted from the core microbiome using machine learning algorithms. The heritable core microbes, therefore, present primary targets for rumen manipulation toward sustainable and environmentally friendly agriculture.R. John Wallace, Goor Sasson, Philip C. Garnsworthy, Ilma Tapio, Emma Gregson ... John L. Williams ... et al
Safety and efficacy of maltol belonging to chemical group 12 when used as flavouring for all animal species
A phenome-wide association study (PheWAS) in the Population Architecture using Genomics and Epidemiology (PAGE) study reveals potential pleiotropy in African Americans
We performed a hypothesis-generating phenome-wide association study (PheWAS) to identify and characterize cross-phenotype associations, where one SNP is associated with two or more phenotypes, between thousands of genetic variants assayed on the Metabochip and hundreds of phenotypes in 5,897 African Americans as part of the Population Architecture using Genomics and Epidemiology (PAGE) I study. The PAGE I study was a National Human Genome Research Institute-funded collaboration of four study sites accessing diverse epidemiologic studies genotyped on the Metabochip, a custom genotyping chip that has dense coverage of regions in the genome previously associated with cardio- metabolic traits and outcomes in mostly European-descent populations. Here we focus on identifying novel phenome-genome relationships, where SNPs are associated with more than one phenotype. To do this, we performed a PheWAS, testing each SNP on the Metabochip for an association with up to 273 phenotypes in the participating PAGE I study sites. We identified 133 putative pleiotropic variants, defined as SNPs associated at an empirically derived p-value threshold of p<0.01 in two or more PAGE study sites for two or more phenotype classes. We further annotated these PheWAS-identified variants using publicly available functional data and local genetic ancestry. Amongst our novel findings is SPARC rs4958487, associated with increased glucose levels and hypertension. SPARC has been implicated in the pathogenesis of diabetes and is also known to have a potential role in fibrosis, a common consequence of multiple conditions including hypertension. The SPARC example and others highlight the potential that PheWAS approaches have in improving our understanding of complex disease architecture by identifying novel relationships between genetic variants and an array of common human phenotypes
- …