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Paragonimiasis, human lung fluke disease, is a foodborne anthropozoonosis caused by the trematodes assigned to Paragonimus and is regarded by the World Health Organization as a Neglected Tropical Disease (NTD). The life cycle of this medically important parasite centres on a complex freshwater biological community that includes two intermediate hosts: a mollusc and a decapod, usually a brachyuran. Although there is a perception that the biology, symptoms, diagnosis and treatment of Paragonimus is well understood, in reality, this is not the case, especially in Africa. Much remains unknown concerning the life-cycle of the parasite, its transmission, the current epidemiology of the disease, diagnosis and the effectiveness of treatment. Furthermore, cases of paragonimiasis may be misdiagnosed as resistant tuberculosis (TB) because of the similar pulmonary symptoms and no remission after anti TB therapy. The endemic foci of human paragonimiasis in Africa have been reported mainly in the forest zones of Upper Guinea (Liberia, Guinea and Ivory Coast) and Lower Guinea (Nigeria, Cameroon, Equatorial Guinea and Gabon). Despite the perceived medical importance of paragonimiasis, relatively little attention has been paid to this NTD since its discovery in Africa in the 1960s. This review focuses on the current understanding of the life cycle and transmission of Paragonimus in Africa, discusses its diagnosis and public health importance and highlights many outstanding gaps in the knowledge that still exist for this NTD.
The Danjon Astrolabe at the Naval Observatory has been traditionally used to determine Universal Time and improve the systematic accuracy of star positions. During the past year, it has been used to determine latitude and longitude at remotely scattered sites for geodetic purposes. Operating this instrument away from the Observatory necessitated a mobile support and timing system rugged enough to operate dependably in ever changing, and sometimes harsh, environmental conditions.
This paper describes the performance of the astrolabe timing and data acquisition system, gives engineering design considerations, and describes the equipment and instrumentation.
Levels of pollution, including contamination by toxic metals, in the Thames estuary reduced over the last four decades of the 20th century. This 2014 study investigates whether the declines in the bioavailabilities of trace metals (Ag, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, Zn) have continued in the 21st century, using a suite of littoral biomonitors also employed in 2001 – the brown seaweed Fucus vesiculosus, the strandline, talitrid amphipod Orchestia gammarellus and the estuarine barnacle Amphibalanus improvisus. Bioaccumulated concentrations represent relative measures of the total bioavailabilities of each metal to the biomonitor over a previous time period, and can be compared over space and over time. Trace metal bioavailabilities varied along the estuary, and, in general, fell between 2001 and 2014, a reflection of the continuing remediation of the Thames estuary from its severely polluted state in the middle of the 20th century.
The present contribution reports on the capture of two adult male specimens of the Asian/Japanese shore crab, Hemigrapsus sanguineus (de Haan, 1835) from Glamorgan, south Wales and Kent, southern England. These represent the first records of this species from mainland Great Britain.
Selwynia, is regarded as a senior subjective synonym of Aphanodactylus (Crustacea: Brachyura: Pinnotheroidea: Aphanodactylidae). This synonymy does not affect the family name Aphanodactylidae. A diagnosis is provided for Selwynia laevis and this species is re-described.
We present results from deep Chandra X-ray observations of the galaxy group NGC 5813. This system shows three pairs of collinear cavities, with each pair associated with an elliptical AGN outburst shock. Due to the relatively regular morphology of this system, and the unique unambiguous detection of three distinct AGN outburst shocks, it is particularly well-suited for the study of AGN feedback and the AGN outburst history. We find that the mean kinetic power is roughly the same for each outburst, and that the total energy associated with the youngest outburst is significantly lower than that of the previous outbursts. This implies that the mean AGN jet power has remained stable for at least 50 Myr, and that the youngest outburst is ongoing. We find that the mean shock heating rate balances the local radiative cooling rate at each shock front, suggesting that AGN outburst shock heating alone is sufficient to offset cooling and establish AGN/ICM feedback within at least the central 30 kpc. Finally, we find non-zero shock front widths that are too large to be explained by particle diffusion, but are instead consistent with arising from broadening of the shock fronts due to propagation through a turbulent ICM with a mean turbulent speed of ~ 70 km s−1.
The present contribution reports on a small collection of leucosiid crabs from Qatar. Four species are reported upon, three of which are new additions to the brachyuran fauna of the Persian Gulf, and one, the first record for the species from Qatar.
The identity of a dotillid intertidal crab from exposed sandy beaches within the Laem Son National Park along the Andaman Coast in Thailand was investigated. The species was identified as Dotilla intermedia De Man, 1888, which represents the first record of this species from Thailand. A description of the species is provided and a lectotype is designated from the type series.
Silica sols were produced with various catalysts (NaOH and HF). Dynamic small strain rheometry was used to probe the formation of the silica network from the sol state through the gelation point into the region of high modulus. These results were related to the dried xerogel properties of surface area and porosity.
Continuous ZrO2 precursor fibers were produced by dry spinning an aqueous zirconium acetate solution containing a soluble yttrium salt and a high molecular weight (MW = 5 × 106) polymer (PEO) to control rheology. A ZrO2-Y2O3 binary composition containing 3 mole % Y2O3 was chosen to control grain growth and to produce tetragonal ZrO2 subsequent to pyrolysis and heat treatment. Fine grained (< 0.3 μm), poly crystalline Zr(Y)O2fibers with diameters between 2 to 12 μm were produced by pyrolysis and heat treatment up to 1400 °C. Fiber tensile strength was measured as a function of processing variables. The objective was to relate flaw populations encountered during strength measurements to processing variables with the goal of controlling and increasing fiber strength.
Solution chemistry routes have been used to prepare single-phased superconducting ceramics of YBaSrCu3O6.9 (1113). Resistivity measurements on air annealed samples showed a superconducting onset temperature of 85 K with zero resistance at 78 K which improves to 81 K upon oxygen annealing. Magnetization data show ca. 78% flux exclusion at 5 K for 1113. X-ray diffraction experiments revealed that an orthorhombic to tetragonal transition occurs near 590°C when 1113 was heated in air. This work has demonstrated that such techniques can be utilized to prepare solid solution material with properties similar to those observed in YBa2Cu3Ox (123).
The use of thin nitride/oxide (NO) stacked dielectrics is common in DRAM storage node structures today. The cell capacitance can be increased without increasing the cell plate area by decreasing the thickness of the dielectric. Combinations of novel storage node structures, textured electrode surfaces, and very thin NO films (equivalent oxide thickness equal <30 Angstroms) are being characterized for use in 256 Mb and 1 Gb DRAM devices as an alternative to premature use of high k dielectric materials. However, the native oxide formed on the surface of the polysilicon bottom electrode prior to dielectric nitride deposition in a standard LPCVD furnace reactor causes the leakage current and reliability properties of the dielectric to degrade for very thin films. Using a vacuum load-locked RTCVD single-wafer reactor with appropriate in situ ammonia and hydrogen pre-deposition surface conditioning, the native oxide can be eliminated and very thin nitride films of much higher quality can be deposited. A comparison between standard batch LPCVD processing and single-wafer RTCVD for silicon nitride deposition has been done and electrical characteristics (including leakage current and time dependent dielectric breakdown) of the films have been measured. These results indicate that use of NO dielectric films may be extended 1–2 more generations of DRAM devices. This will allow more time for improving the quality of high k dielectric films.