1,165 research outputs found
Present day status and future of nature conservation in the Republic of Malawi
When Malawi (formerly Nyasaland) became independent in 1964 the status and future of its game reserves were in jeopardy. The former administration had adopted a policy of benign neglect towards the country's wildlife areas (Anon 1963), and the remnants of the Department of Game, Fish and Tsetse Control had been absorbed by the Forestry Department in 1963. Fortunately the Life President of Malawi, Dr H Kamuzu Banda, took a strong interest in wildlife conservation and it was only his personal intervention, and the advent of independence, that saved the former Lengwe Game Reserve from deproclamation (Hayes 1967) as planned by the colonial administration. With the Life President's encouragement and the dedicated efforts of the staff responsible for wildlife, the tide which had been running strongly against nature conservation was turned, culminating in the establishment of a separate Department of National Parks and Wildlife only a decade after independence
Seismic signature of subduction termination from teleseismic P- and S-wave arrival-time tomography : the case of northern Borneo
Acknowledgments S.P. acknowledges support from the Natural Environmental Research Council (NERC) Grant NE/R013500/1 and from the European Union's Horizon 2020 Research and Innovation Program under Marie Skłodowska-Curie Grant Agreement 790203. We thank the TanDEM-X Science Communication Team (German Aerospace Center (DLR) e.V.) for providing TanDEM topographic data. We thank the NERC Geophysical Equipment Facility for loan 1038 and seismometers loaned by the University of Cambridge and Aberdeen. We would like to thank Zhong-Hai Li and an anonymous reviewer for their constructive feedback during the review process.Peer reviewedPostprin
Avian olfactory receptor gene repertoires: evidence for a well-developed sense of smell in birds?
Among vertebrates, the sense of smell is mediated by olfactory receptors (ORs) expressed in sensory neurons within the olfactory epithelium. Comparative genomic studies suggest that the olfactory acuity of mammalian species correlates positively with both the total number and the proportion of functional OR genes encoded in their genomes. In contrast to mammals, avian olfaction is poorly understood, with birds widely regarded as relying primarily on visual and auditory inputs. Here, we show that in nine bird species from seven orders (blue tit, Cyanistes caeruleus; black coucal, Centropus grillii; brown kiwi, Apteryx australis; canary, Serinus canaria; galah, Eolophus roseicapillus; red jungle fowl, Gallus gallus; kakapo, Strigops habroptilus; mallard, Anas platyrhynchos; snow petrel, Pagodroma nivea), the majority of amplified OR sequences are predicted to be from potentially functional genes. This finding is somewhat surprising as one previous report suggested that the majority of OR genes in an avian (red jungle fowl) genomic sequence are non-functional pseudogenes. We also show that it is not the estimated proportion of potentially functional OR genes, but rather the estimated total number of OR genes that correlates positively with relative olfactory bulb size, an anatomical correlate of olfactory capability. We further demonstrate that all the nine bird genomes examined encode OR genes belonging to a large gene clade, termed γ-c, the expansion of which appears to be a shared characteristic of class Aves. In summary, our findings suggest that olfaction in birds may be a more important sense than generally believed
Quantum gates with neutral atoms: Controlling collisional interactions in time dependent traps
We theoretically study specific schemes for performing a fundamental
two-qubit quantum gate via controlled atomic collisions by switching
microscopic potentials. In particular we calculate the fidelity of a gate
operation for a configuration where a potential barrier between two atoms is
instantaneously removed and restored after a certain time. Possible
implementations could be based on microtraps created by magnetic and electric
fields, or potentials induced by laser light.Comment: 10 pages, 3 figure
Family Unification on an Orbifold
We construct a family-unified model on a Z_2xZ_2 orbifold in five dimensions.
The model is based on a supersymmetric SU(7) gauge theory. The gauge group is
broken by orbifold boundary conditions to a product of grand unified SU(5) and
SU(2)xU(1) flavor symmetry. The structure of Yukawa matrices is generated by an
interplay between spontaneous breaking of flavor symmetry and geometric factors
arising due to field localization in the extra dimension.Comment: 13 page
Spatial Stability of Incompressible Attachment-Line Flow
Linear stability analysis of incompressible attachment-line flow is presented within the spatial framework. The system of perturbation equations is solved using spectral collocation. This system has been solved in the past using the temporal approach and the current results are shown to be in excellent agreement with neutral temporal calculations. Results amenable to direct comparison with experiments are then presented for the case of zero suction. The global solution method utilized for solving the eigenproblem yields, aside from the well-understood primary mode, the full spectrum of least-damped waves. Of those, a new mode, well separated from the continuous spectrum is singled out and discussed. Further, relaxation of the condition of decaying perturbations in the far-field results in the appearance of sinusoidal modes akin to those found in the classical Orr-Sommerfeld problem. Finally, the continuous spectrum is demonstrated to be amenable to asymptotic analysis. Expressions are derived for the location, in parameter space, of the continuous spectrum, as well as for the limiting cases of practical interest. In the large Reynolds number limit the continuous spectrum is demonstrated to be identical to that of the Orr-Sommerfeld equation
Theory of a Higher Order Phase Transition: Superconducting Transition in BKBO
We describe here the properties expected of a higher (with emphasis on the
order fourth) order phase transition. The order is identified in the sense
first noted by Ehrenfest, namely in terms of the temperature dependence of the
ordered state free energy near the phase boundary. We have derived an equation
for the phase boundary in terms of the discontinuities in thermodynamic
observables, developed a Ginzburg-Landau free energy and studied the
thermodynamic and magnetic properties. We also discuss the current status of
experiments on and other based superconductors,
the expectations for parameters and examine alternative explanations of the
experimental results.Comment: 18 pages, no figure
Collective dynamics of internal states in a Bose gas
Theory for the Rabi and internal Josephson effects in an interacting Bose gas
in the cold collision regime is presented. By using microscopic transport
equation for the density matrix the problem is mapped onto a problem of
precession of two coupled classical spins. In the absence of an external
excitation field our results agree with the theory for the density induced
frequency shifts in atomic clocks. In the presence of the external field, the
internal Josephson effect takes place in a condensed Bose gas as well as in a
non-condensed gas. The crossover from Rabi oscillations to the Josephson
oscillations as a function of interaction strength is studied in detail.Comment: 18 pages, 2 figure
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