4,118 research outputs found
Global priorities for conservation across multiple dimensions of mammalian diversity
Conservation priorities that are based on species distribution, endemism, and vulnerability may underrepresent biologically unique species as well as their functional roles and evolutionary histories. To ensure that priorities are biologically comprehensive, multiple dimensions of diversity must be considered. Further, understanding how the different dimensions relate to one another spatially is important for conservation prioritization, but the relationship remains poorly understood. Here, we use spatial conservation planning to (i) identify and compare priority regions for global mammal conservation across three key dimensions of biodiversity-taxonomic, phylogenetic, and traits-and (ii) determine the overlap of these regions with the locations of threatened species and existing protected areas. We show that priority areas for mammal conservation exhibit low overlap across the three dimensions, highlighting the need for an integrative approach for biodiversity conservation. Additionally, currently protected areas poorly represent the three dimensions of mammalian biodiversity. We identify areas of high conservation priority among and across the dimensions that should receive special attention for expanding the global protected area network. These high-priority areas, combined with areas of high priority for other taxonomic groups and with social, economic, and political considerations, provide a biological foundation for future conservation planning efforts
Preferential attachment in the protein network evolution
The Saccharomyces cerevisiae protein-protein interaction map, as well as many
natural and man-made networks, shares the scale-free topology. The preferential
attachment model was suggested as a generic network evolution model that yields
this universal topology. However, it is not clear that the model assumptions
hold for the protein interaction network. Using a cross genome comparison we
show that (a) the older a protein, the better connected it is, and (b) The
number of interactions a protein gains during its evolution is proportional to
its connectivity. Therefore, preferential attachment governs the protein
network evolution. The evolutionary mechanism leading to such preference and
some implications are discussed.Comment: Minor changes per referees requests; to appear in PR
Lignin biomarkers as tracers of mercury sources in lakes water column
This study presents the role of specific terrigenous organic compounds as important vectors of mercury (Hg) transported from watersheds to lakes of the Canadian boreal forest. In order to differentiate the autochthonous from the allochthonous organic matter (OM), lignin derived biomarker signatures [Lambda, S/V, C/V, P/(V ? S), 3,5-Bd/V and (Ad/Al)v] were used. Since lignin is exclusively produced by terrigenous plants, this approach can give a non equivocal picture of the watershed inputs to the lakes. Moreover, it allows a characterization of the source of OM and its state of degradation. The water column of six lakes from the Canadian Shield was sampled monthly between June and September 2005. Lake total dissolved Hg concentrations and Lambda were positively correlated, meaning that Hg and ligneous inputs are linked (dissolved OM r2 = 0.62, p\0.0001; particulate OM r2 = 0.76, p\0.0001). Ratios of P/(V ? S) and 3,5-Bd/V from both dissolved OM and particulate OM of the water column suggest an inverse relationship between the progressive state of pedogenesis and maturation of the OM in soil before entering the lake, and the Hg concentrations in the water column. No relation was found between Hg levels in the lakes and the watershed flora composition—angiosperm versus gymnosperm or woody versus non-woody compounds. This study has significant implications for watershed management of ecosystems since limiting fresh terrestrial OM inputs should reduce Hg inputs to the aquatic systems. This is particularly the case for largescale land-use impacts, such as deforestation, agriculture and urbanization, associated to large quantities of soil OM being transferred to aquatic systems
Excitations are localized and relaxation is hierarchical in glass-forming liquids
For several atomistic models of glass formers, at conditions below their
glassy dynamics onset temperatures, , we use importance
sampling of trajectory space to study the structure, statistics and dynamics of
excitations responsible for structural relaxation. Excitations are detected in
terms of persistent particle displacements of length . At supercooled
conditions, for of the order of or smaller than a particle diameter, we
find that excitations are associated with correlated particle motions that are
sparse and localized, occupying a volume with an average radius that is
temperature independent and no larger than a few particle diameters. We show
that the statistics and dynamics of these excitations are facilitated and
hierarchical. Excitation energy scales grow logarithmically with .
Excitations at one point in space facilitate the birth and death of excitations
at neighboring locations, and space-time excitation structures are microcosms
of heterogeneous dynamics at larger scales. This nature of dynamics becomes
increasingly dominant as temperature is lowered. We show that slowing of
dynamics upon decreasing temperature below is the result of a
decreasing concentration of excitations and concomitant growing hierarchical
length scales, and further that the structural relaxation time follows
the parabolic law, , for , where , and
can be predicted quantitatively from dynamics at short time
scales. Particle motion is facilitated and directional, and we show this
becomes more apparent with decreasing . We show that stringlike motion is a
natural consequence of facilitated, hierarchical dynamics.Comment: 15 pages, 6 figures, + links to movies; To appear in Phys. Rev.
The limits of social class in explaining ethnic gaps in educational attainment
This paper reports an analysis of the educational attainment and progress between age 11 and age 14 of over 14,500 students from the nationally representative Longitudinal Study of Young People in England (LSYPE). The mean attainment gap in national tests at age 14 between White British and several ethnic minority groups were large, more than three times the size of the gender gap, but at the same time only about one-third of the size of the social class gap. Socio-economic variables could account for the attainment gaps for Black African, Pakistani and Bangladeshi students, but not for Black Caribbean students. Further controls for parental and student attitudes, expectations and behaviours indicated minority ethnic groups were on average more advantaged on these measures than White British students, but this was not reflected proportionately in their levels of attainment. Black Caribbean students were distinctive as the only group making less progress than White British students between age 11 and 14 and this could not be accounted for by any of the measured contextual variables. Possible explanations for the White British-Black Caribbean gap are considered
Discovery of a New WZ Sagittae Type Cataclysmic Variable in the Kepler/K2 Data
We identify a new, bright transient in the Kepler/K2 Campaign 11 field. Its
light curve rises over seven magnitudes in a day and then declines three
magnitudes over a month before quickly fading another two magnitudes. The
transient was still detectable at the end of the campaign. The light curve is
consistent with a WZ~Sge type dwarf nova outburst. Early superhumps with a
period of 82 minutes are seen in the first 10 days and suggest that this is the
orbital period of the binary which is typical for the WZ~Sge class. Strong
superhump oscillations develop ten days after peak brightness with periods
ranging between 83 and 84 minutes. At 25 days after the peak brightness a bump
in the light curve appears to signal a subtle rebrightening phase implying that
this was an unusual type-A outburst. This is the only WZ~Sge type system
observed by Kepler/K2 during an outburst. The early rise of this outburst is
well-fit with a broken power law. In first 10 hours the system brightened
linearly and then transitioned to a steep rise with a power law index of 4.8.
Looking at archival Kepler/K2 data and new TESS observations, a linear rise in
the first several hours at the initiation of a superoutburst appears to be
common in SU~UMa stars.Comment: 11 pages, 14 figures, 2 tables, accepted to appear in the Monthly
Notices of the Royal Astronomical Societ
Kinstate intervention in ethnic conflicts : Albania and Turkey compared
Albania and Turkey did not act in overtly irredentist ways towards their ethnic brethren in neighboring states after the end of communism. Why, nonetheless, did Albania facilitate the increase of ethnic conflict in Kosovo and Macedonia, while Turkey did not, with respect to the Turks of Bulgaria? I argue that kin-states undergoing transition are more prone to intervene in external conflicts than states that are not, regardless of the salience of minority demands in the host-state. The transition weakens the institutions of the kin-state. Experiencing limited institutional constraints, self-seeking state officials create alliances with secessionist and autonomist movements across borders alongside their own ideological, clan-based and particularistic interests. Such alliances are often utilized to advance radical domestic agendas. Unlike in Albania's transition environment, in Turkey there were no emerging elites that could potentially form alliances and use external movements to legitimize their own domestic existence or claims
Stability and enzymatic studies with omeprazole: hydroxypropyl-β-cyclodextrin
The original publication is available at www.springerlink.com. A publicação original está disponível em www.springerlink.comOmeprazole (OME) exhibits low stability to light, heat and humidity. In stress conditions OME stability should improve under inclusion complex form with hydroxypropyl-b-cyclodextrin (HPbCD). Stability of OME, its physical mixture (PM) with HPbCD and OME:HPbCD inclusion complex was assessed during 60 days. The inclusion complexes were prepared by kneading and freezedrying techniques and characterized by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). A molecular modelling was also held to predict the most probable tridimensional conformation of inclusion complex OME:HPbCD. The inhibitory activity of free and complexed OME on selected enzymes, namely, papain (protease model of the proton pump) and acetylcholinesterase (enzyme present in cholinergic neurons and also involved in Alzheimer’s disease) was compared. The results obtained show that HPbCD do not protect against OME degradation, in any prepared powder, in the presence of light, heat and humidity. This may indicate that the reactive group of OME is not included in the HPbCD cavity.
This fact is supported by molecular modelling data, which demonstrated that 2-pyridylmethyl group of OME is not included into the cyclodextrin cavity. In relation to enzymatic assays it was observed that free OME and OME in the binary systems showed identical inhibitory activity on papain and acethylcolinesterase, concluding that HPbCD do not affect OME activity on these two enzymes
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