2,445 research outputs found

    Variations in community perceptions of ecosystem services within the Tana River estuary, Kenya: Implications for ocean governance

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    Coastal communities in the Tana estuary, Kenya, rely on a variety of economic sectors linked to ecosystem services, including small-scale fisheries (SSF), commercial prawn fisheries, and tourism. Despite its environmental and social importance, the estuary has been negatively impacted by overexploitation, pollution, and climate change. As a result, developing integrated management approaches for this area is a priority. The integrated approach to ecosystem services (ES) evaluation has widespread support because it emphasizes people’s views of ecological value to human well-being and aims to provide a solution to the rapid depletion of our planet’s natural resources. This study applied mixed methods to understand the perspectives of the communities on ES. It was hypothesized that perceptions of ES differ across communities with different socioeconomic characteristics, and this hypothesis was tested in two communities (Ozi and Kipini) that share the same ecosystem but have different socioeconomic characteristics. Kipini is an area near the ocean, whereas Ozi is a rural area further upstream. Differences were noted in the valuation of cultural services, while there were similarities in provisioning and regulating services. Mangroves, other trees, and river systems were considered to have higher ES provision than the ocean, floodplains, and settlement areas. The Ozi community ranked the ocean higher than the Kipini community, even though Ozi was located further upstream from the ocean; consequently, the perception that communities benefit more from resources that they are close to could be false. The relevance of using social ES identification to determine the distribution of benefits from coastal ES is highlighted in this study and will be beneficial for informing decision-making and developing all-inclusive governance structures

    Cosmological Analogues of the Bartnik--McKinnon Solutions

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    We present a numerical classification of the spherically symmetric, static solutions to the Einstein--Yang--Mills equations with cosmological constant Λ\Lambda. We find three qualitatively different classes of configurations, where the solutions in each class are characterized by the value of Λ\Lambda and the number of nodes, nn, of the Yang--Mills amplitude. For sufficiently small, positive values of the cosmological constant, \Lambda < \Llow(n), the solutions generalize the Bartnik--McKinnon solitons, which are now surrounded by a cosmological horizon and approach the deSitter geometry in the asymptotic region. For a discrete set of values Λreg(n)>Λcrit(n)\Lambda_{\rm reg}(n) > \Lambda_{\rm crit}(n), the solutions are topologically 33--spheres, the ground state (n=1)(n=1) being the Einstein Universe. In the intermediate region, that is for \Llow(n) < \Lambda < \Lhig(n), there exists a discrete family of global solutions with horizon and ``finite size''.Comment: 16 pages, LaTeX, 9 Postscript figures, uses epsf.st

    Cholangitis and Budd Chiari Syndrome as Complications of Simple Cystic Liver Disease

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    We report the case of a 63 year old woman who developed the complications of cholangitis and Budd Chiari syndrome secondary to polycystic disease of the liver. The two complications were not present simultaneously, and both resolved after decompression of the liver cysts

    Observatory/data centre partnerships and the VO-centric archive: The JCMT Science Archive experience

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    We present, as a case study, a description of the partnership between an observatory (JCMT) and a data centre (CADC) that led to the development of the JCMT Science Archive (JSA). The JSA is a successful example of a service designed to use Virtual Observatory (VO) technologies from the start. We describe the motivation, process and lessons learned from this approach.Comment: Accepted for publication in the second Astronomy & Computing Special Issue on the Virtual Observatory; 10 pages, 5 figure

    Physical properties of dense cores in Orion B9

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    We aim to determine the physical and chemical properties of dense cores in Orion B9. We observed the NH3(1,1) and (2,2), and the N2H+(3-2) lines towards the submm peak positions. These data are used in conjunction with our LABOCA 870 micron dust continuum data. The gas kinetic temperature in the cores is between ~9.4-13.9 K. The non-thermal velocity dispersion is subsonic in most of the cores. The non-thermal linewidth in protostellar cores appears to increase with increasing bolometric luminosity. The core masses are very likely drawn from the same parent distribution as the core masses in Orion B North. Starless cores in the region are likely to be gravitationally bound, and thus prestellar. Some of the cores have a lower radial velocity than the systemic velocity of the region, suggesting that they are members of the "low-velocity part" of Orion B. The observed core-separation distances deviate from the corresponding random-like model distributions. The distances between the nearest-neighbours are comparable to the thermal Jeans length. The fractional abundances of NH3 and N2H+ in the cores are ~1.5-9.8x10^{-8} and ~0.2-5.9x10^{-10}, respectively. The NH3 abundance appears to decrease with increasing H2 column and number densities. The NH3/N2H+ column density ratio is larger in starless cores than in cores with embedded protostars. The core population in Orion B9 is comparable in physical properties to those in nearby low-mass star-forming regions. It is unclear if the origin of cores could be explained by turbulent fragmentation. On the other hand, many of the core properties conform with the picture of dynamic core evolution. The Orion B9 region has probably been influenced by the feedback from the nearby Ori OB 1b group, and the fragmentation of the parental cloud into cores could be caused by gravitational instability.Comment: 17 pages, 11 figures, 7 tables. Accepted for publication in Astronomy and Astrophysics. Version 2: minor language corrections adde

    Temperature dependent c-axis hole mobilities in rubrene single crystals determined by time-of-flight

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    Hole mobilities (μ) in rubrene single crystals (space group Cmca) along the crystallographic c-axis have been investigated as a function of temperature and applied electric field by the time-of-fight method. Measurements demonstrate an inverse power law dependence on temperature, namely,μ=μ0T−n with n = 1.8, from room temperature down to 180 K. At 296 K, the average value of μ was found to be 0.29 cm2/Vs increasing to an average value of 0.70 cm2/Vs at 180 K. Below 180 K a decrease in mobility is observed with further cooling. Overall, these results confirm the anisotropic nature of transport in rubrene crystals as well as the generality of the inverse power law temperature dependence that is observed for field effect mobility measurements in the a-b crystal plane

    Determination of the carrier concentration in InGaAsN∕GaAs single quantum wells using Raman scattering

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    Raman scattering from longitudinal optical phonon-plasmon coupled mode was observed in a series of InGaAsN∕GaAs single quantum well samples grown by metalorganic vapor phase epitaxy. The phonon-plasmon mode spectra were fitted with the dielectric constant function based on Drude model that contains contributions from both lattice vibrations and conduction electrons. The carrier concentration is calculated directly from the plasmon frequency, which is obtained from the fitting procedure. An empirical expression for the electron concentration, [n], in InGaAsN∕GaAs samples is determined as [n]≈{2.35×1016(ωm−502)}cm−3, where ωm is the peak of the upper frequency branch, L+, of the phonon-plasmon mode measured in unit of cm−1. The phonon-plasmon coupled mode was also investigated in rapid thermally annealed samples

    Combination and monotherapy of Leishmania major infection in BALB/c mice using plant extracts and herbicides

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    Background & objectives: Leishmaniasis is a growing health problem in many parts of the world. Efforts to findnew chemotherapeutics for leishmaniasis remain a priority. This study was carried out to determine the effect ofcombination and monotherapies using plant extracts and herbicides on Leishmania major infection in BALB/cmice.Methods: The herbicides and saponin extract were purchased from Sigma. Roots of Plumbago capensis werecollected from Karura forest, Nairobi, Kenya. Plant extractions were done in KEMRI at Center for TraditionalMedicines and Drugs Research.Results: Lesion sizes after infection of BALB/c mice were similar in all the experimental groups till the onset oftherapeutic treatments (p >0.05). At 15 days post-treatment, significant differences (p < 0.05) were discerned inthe lesion sizes of the BALB/c mice in all the mono- and combined-treated groups. However, the combinedtherapies caused total elimination of the parasites from the lesions and significantly reduced parasite burden inliver and spleen compared to the untreated controls at the end of the experiment.Interpretation & conclusion: The results of this study demonstrate that combination therapy using alternativeadministration of saponin, acriflavine, trifluralin and plumbagin is effective in treating L. major infection inmice. In this regard, an investigation into the efficacy of these combined therapies against other Leishmaniastrains should be explored further. Furthermore, studies with these combination therapies should be done onnon-human primates such as the vervet monkey (Cercopithecus aethiops)

    A Genetic Algorithm-Based Exploration of Three Filament Models: A Case for the Magnetic Support of the G11.11-0.12 Infrared-Dark Cloud

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    The G11.11-0.12 infrared-dark cloud has a filamentary appearance, both in extinction against the diffuse infrared emission of the Galactic plane and in emission at 850 microns. We use a novel computational technique based on an advanced genetic algorithm to explore thoroughly 3 different models of self-gravitating, pressure truncated filaments and to constrain their parameters. Specifically, the models tested are the non-magnetic Ostriker (1964) model, a generalized version of the magnetic Stodolkiewicz (1963) model, and the magnetic Fiege & Pudritz (2000) model. Previous results showed that G11.11-0.12 has a much steeper r^{-4} radial density profile than other filaments, where the density varies approximately as r^{-2}, and that this steep density profile is consistent with the Ostriker (1964) model. We present a more complete analysis that shows that the radial structure of G11.11-0.12 is consistent with regimes of each of these models. All of the magnetic models that agree with the data are threaded by a dominant poloidal magnetic field, and most have dynamically significant fields. Thus, G11.11-0.12 is an excellent candidate for radial support by a magnetic field that is predominantly poloidal. We predict the polarization patterns expected for both magnetic models and show that the two magnetic models produce different polarization patterns that should be distingished by observations.Comment: To appear in Ap.J. Dec. 1 edition, volume 616. 40 pages and 42 figures. Figures are severely reduced to satisfy astro-ph size limits. A version with higher quality figures is available by contacting the first autho

    Evidence for transient clumps and gas chemical evolution in the CS core of L673

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    We present FCRAO maps as well as combined BIMA and FCRAO maps of the high density molecular emission towards the CS core in the L673 region. With the FCRAO telescope, we mapped the emission in the CS(2-1), C34S(2-1), HCO+(1-0), and H13CO+(1-0) lines. The high density molecular emission, which arises from a filamentary structure oriented in the NW-SE direction, shows clear morphological differences for each molecule. We find that HCO+ has an extremely high optical depth, and that the H13CO+ emission is well correlated with submm sources. The BIMA and FCRAO combined maps recover emission from a lot of other structure which was previously undetected or only marginally detected, and show an overall aspect of a filamentary structure connecting several intense clumps. We found a total 15 clumps in our combined data cube, all of them resolved by our angular resolution, with diameters in the 0.03-0.09 pc range. We find a clear segregation between the northern and southern region of the map: the northern section shows the less chemically evolved gas and less massive but more numerous clumps, while the southern region is dominated by the largest and most massive clump, and contains the more evolved gas, as traced by emission of late-time molecules. We find that the derived clump masses are below the virial mass, and that the clumps masses become closer to the virial mass when they get bigger and more massive. This supports the idea that these clumps must be transient, and only the more massive ones have a chance to last long enough to form stars. The clumps we detect are probably in an earlier evolutionary stage than the ``starless cores'' reported recently in the literature. Only the most massive one has properties similar to a ``starless core''.Comment: 12 pages, 8 figures, accepted for publication in Astronomy & Astrophysics; minor revisions after language editin
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