Tidal period upwelling within Raine Island Entrance Great Barrier Reef

Temperature and current measurements collected from November 1981 to May 1982 at the head of Raine Island Entrance reveal tidally-induced upwelling of cold continental slope water onto the continental shelf. Daily tidal motions account for approximately 80% of the total cross-shelf eddy heat flux of 0.79 ± 1.01 cal cm−2 s−1. Although temperature and current fluctuations are principally of semidiurnal period, the heat flux is principally at diurnal period. Based on empirical nutrient-temperature relations we estimate the onshore inorganic nutrient fluxes to be 0.9 (±1.2) × 10−2 mmol m−2 s−1 for nitrate, 0.6 (±0.8) × 10−2 mmol m−2 s−1 for silicate and 0.7 (±0.9) × 10−3 mmol m−2 s−1 for phosphate.The upwelling is explained in terms of fluid withdrawal-type mechanisms in which nutrient-rich thermocline water below 100 m depth is drawn onto the shallow (40 m) shelf during the flood. We suggest that this tidal period inundation of the outer reefs is an important mechanism for effectively upgrading nominally low nutrient levels. Reef growth is expected to be most prolific near the shelf break where the time-integrated contribution of the upwelling is greatest

Coral Growth Related to Resuspension of Bottom Sediments

The determination of coral skeletal growth, from both a biological and a geological standpoint, has long presented difficulties in ease and accuracy of measurement. As a consequence, factors which limit growth are only beginning to be investigated. Radiometric methods using natural radioactive series nuclides have recently been used to determine the growth rate of certain corals. In addition, X radiographs coupled with 90Sr-induced autoradiographs have demonstrated that at least some hermatypic corals record annual growth bands in their skeletons. Once annual banding is confirmed, measurement of band widths allows precise determination of yearly growth increments. It is thus possible to compare inter- and intraspecific coral growth rates from different areas with pertinent environmental variables and to educe possible correlations. We describe here an investigation of the effects of resuspension of bottom sediments on the growth rate, as determined by a 228Ra technique and X radiography of Montastrea annularis in different parts of Discovery Bay, Jamaica. Such a study is unique both because the annual nature of growth bands is established for the most important reef-forming coral in the Caribbean and because radiometric and radiographic techniques are extended to measure growth rates as a function of environmental parameters

The Rebirth of Airships

Until the outbreak of the Second World War, uncertainty existed whether airships and airplanes would dominate intercontinental passenger transportation. The massive investments in fixed-wing aircraft during these hostilities made airplanes the decisive winner, and relegated airships to a negligible role in transportation. As the 21st Century progresses, airships are making a comeback fueled by the 21st Century progresses, airships are making a comeback fueled by the growing demand for air cargo, the unique environmental and operational characteristics of buoyant flight, and advances in engineering science and materials. This paper examines the market niche for airships that exists between air and marine transport and the inherent advantages and disadvantages of this mode of transportation. The economics of airships are considered in light of their past achievements and current designs. The paper concludes with the discussion of two potential applications. A long haul mission for airships between Hawaii and the U.S. mainland is considered for perishable freight, and a short haul mission for airships in northern Canada is considered for the transport of freight and passengers to remote communities

Foraminiferal Evidence of Younger Dryas Age Cooling on the British Columbia Shelf

Cluster analysis of foraminifera from a ~12,000-9000 radiocarbon year old piston core from Goose Island Trough, Queen Charlotte Sound, indicates that a cold interval correlative with the Younger Dryas stadial occurred during a shallow water phase. The reduction in depth was caused by the passage across the area, between 11,500 and 10,000 years BP, of a glacial forebulge associated with the retreat of the Late Wisconsinian ice sheets. Published sedimentological evidence indicate that water depths decreased to ~75-90 m, placing the site above the permanent North Pacific pycnocline (100 m). Low salinity-near glacial conditions, at these depths, between -11,100 and 10,000 years BP were recognized by abundant populations of Cassidulina reniforme and lslandiella helenae. This cold interval has also been recognized in cores from elsewhere in Queen Charlotte Sound. The depressed salinity and temperature may have resulted from a modification of regional weather patterns. Decreased mean continental summer temperatures could have reduced the seasonal influence of the North Pacific High and lengthened that of the Aleutian Low. This would have resulted in a near continuous onshore surface Ekman transport and enhanced coastal runoff, effectively blocking the movement onto the shelf of deep, saline, warm water of the California Undercurrent. The resultant isolated inshore basin comprised of present-day Hecate Strait and Queen Charlotte Sound is tentatively named the "Hecate Sea". By ~10,000 years BP, weather and ocean circulation had returned to near modern patterns as indicated by the disappearance of lslandiella helenae and by the development of an Epistominella vitrea - dominated biofacies.L'analyse des groupements effectuée sur des populations de foraminifères d'une carotte à piston couvrant la période de 12 000 à 9000 ans BP, provenant du Goose Island Trough, dans le bassin de la Reine-Charlotte, démontre l'existence d'un intervalle froid contemporain du Dryas récent. Il coïncide avec une phase à bathymétrie réduite qui résulte du déplacement vers l'est, entre 11 500 et 10 000 ans BP, du bombement isostatique associé à l'Inlandsis de la Cordillière à la suite de son retrait. Des données sédimentologiques publiées montrent que la profondeur a diminué jusqu'à ~75-90 m, amenant le site étudié au-dessus de la pycnocline permanente du Pacifique Nord (100 m). L'existence de conditions hyposalines de type glaciaire, à ces profondeurs, entre 11 100 et 10 000 ans BP ont été reconnues grâce à la présence d'assemblages à Cassidulina reniforme et lslandiella helenae. Cet intervalle froid a également été reconnu ailleurs dans le bassin de la Reine-Charlotte. Les salinités et les températures réduites sont peut-être le résultat d'un changement dans les configurations météorologiques régionales. Des températures estivales plus basses sur le continent auraient réduit l'influence saisonnière de l'anticyclone du Pacifique Nord et rallongé celle de la dépression des Aloutiennes. Ceci aurait engendré un transport d'Ekman de surface quasi permanent vers la côte et provoqué une augmentation des précipitations, ayant eu pour effet de bloquer la remontée des eaux salées et tièdes du sous-courant de Californie. Nous proposons d'appeler « Mer d'Hécate » le bassin côtier ainsi créé comprenant l'actuel détroit d'Hécate et le bassin de la Reine-Charlotte. Dès avant ~10 000 ans BP, les circulations atmosphérique et océanique étaient revenues à une configuration presque moderne.Die Analyse der Foraminiferen-Anhàufungen von einem -12,000-9000 Radiokarbonjahre alten Bohrkern von Goose Island Trough im Queen Charlotte Sund zeigt, daB ein kaltes Intervall gleichzeitig mit dem jùngeren Dryas-Stadium wàhrend einer Phase seichten Wassers eintrat. Die Verringerung der Tiefe wurde durch die Passage einer glazialen Emporwôlbung zwischen 11,500 und 10,000 Jahren v.u.Z. quer durch das Gebiet bewirkt, zusammen mit dem Rùckzug der Eisdecken vom spàten Wisconsinium. Die verôfent-lichten sedimentologischen Belege zeigen, daf3 die Wassertiefen auf -75-90 m abnahmen, und so den Platz ùber die stàndige Dichte-Gradient des Nordpazifik (100 m) stellten. Fast glaziale Bedingungen mit niedrigem Salzgehalt wurden in diesen Tiefen zwischen -11,100 und 10,000 Jahren v.u.Z. auf Grund von reichlichen Populationen von Cassidulina reniforme und lslandiella helenae erkannt. Der verringerte Salzgehalt und die niedrigere Temperatur kônnten auch durch eine Ànderung der regionalen Wetterkonstellationen bewirkt worden sein. Gesunkene durchschnittliche kontinentale Sommertemperaturen kônnten den jahreszeitlichen EinfluB des nordpazifischen Hochs verringert und den des atlantischen Tiefs verlàngert haben. Das kônnte einen fast kontinuierlichen Ekman-Transport an der Oberflâche zur Kùste hin bewirkt und die Kùsten-Niederschlàge verstàrkt haben, und so ware die Bewegung von tiefem, salzhaltigem warmem Wasser der kalifornischen Unterstromung zur Terrasse hin blockiert worden. Das daraus resultierende isolierte Binnen-Becken, bestehend aus der heutigen Hecate-Meerenge und dem Queen Charlotte Sund, wird probeweise "Hecate Sea" genannt. Um -10,000 Jahre v.u.Z. sind Wetter und Ozeanstromung zu nahezu modernen Mustern zuruckgekehrt

Interaction of internal waves and mean flow observed near a coast

Vortex stretching has been proposed as a possible mechanism by which internal waves can extract energy from the mean flow. Relationships between the slowly varying (ω \u3c 0.25 cpd) and rapidly varying (0.13 cph \u3c ω \u3c 0.5 cph) components of the flow have been examined in a 4-month-long data set taken off the coast of British Columbia. The rapidly varying component of horizontal velocity generally rotates clockwise, and is in rough agreement with internal wave dynamics. It is horizontally incoherent within a distance of 10 km and is vertically coherent across the water column with a nearly 180° phase change. Scatter plots show that the wavefield is anisotropic, with the Reynolds stresses generally obeying uv \u3c 0, vw \u3c 0 and uw \u3e 0, where (u, v, w) are the fluctuating velocity components in the (onshore, alongshore, upward) directions. Instances have been found in which time variations of uv and the mean horizontal shear rate Vx are negatively correlated, with an implied horizontal viscosity of VH ∼ (3 ± 2) × 105 cm2/s. No correlation of vw and the mean vertical shear Vz is found. It is suggested that nonlocal behavior is important because propagation times in the vertical are smaller than the interaction times of the wave packets. With the observed shear rates and the wave energy levels, the vertical viscosity is unlikely to be beyond the range ± 20 cm2/s

Managed moves: schools collaborating for collective gain

Government guidance in the United Kingdom encourages groups of schools to take collective responsibility for supporting and making provision for excluded pupils and those at risk of exclusion. Managed-moves are one way that some schools and authorities are enacting such guidance. This paper presents the results of an evaluation of one such scheme. The scheme, involving seven neighbouring secondary schools, was nearing its first year of completion. The paper draws primarily on interview data with pupils, parents and school staff to describe a number of positive outcomes associated with the scheme and to explore how these were achieved. We found that while some of these could be attributed directly to the managed-move, others arose from the more inclusive ethos and practices of particular schools. The concepts of tailored support, care and commitment emerged as strong themes that underpinned the various practical ways in which some schools in the cluster were able to re-engage 'at-risk' pupils. As managed moves become more widely practiced it will be important to remember that it is how the move proceeds and develops rather than the move itself that will ultimately make the difference for troubled and troublesome pupils

Parabolic Deployable Antenna

A deployable antenna is described. The antenna comprises a mesh attached to foldable ribs, a hub and a sub-reflector. The antenna can be stowed in a tight space for launching in space, and later deployed by extending out of its container. The antenna is designed to work in the Ka band or other bands and can increase data rates and function as a radio antenna

Raman Life Detection Instrument Development for Icy Worlds

The objective of this project is to develop a compact, high sensitivity Raman sensor for detection of life signatures in a flow cell configuration to enable bio-exploration and life detection during future mission to our Solar Systems Icy Worlds. The specific project objectives are the following: 1) Develop a Raman spectroscopy liquid analysis sensor for biosignatures; 2) Demonstrate applicability towards a future Enceladus or other Icy Worlds missions; 3) Establish key parameters for integration with the ARC Sample Processor for Life on Icy Worlds (SPLIce); 4) Position ARC for a successful response to upcoming Enceladus or other Icy World mission instrument opportunities

Atomic Hydrogen and Star Formation in the Bridge/Ring Interacting Galaxy Pair NGC 7714/7715 (Arp 284)

We present high spatial resolution 21 cm HI maps of the interacting galaxy pair NGC 7714/7715. We detect a massive (2 x 10**9 M(sun)) HI bridge connecting the galaxies that is parallel to but offset from the stellar bridge. A chain of HII regions traces the gaseous bridge, with H-alpha peaks near but not on the HI maxima. An HI tidal tail is also detected to the east of the smaller galaxy NGC 7715, similarly offset from a stellar tail. The strong partial stellar ring on the eastern side of NGC 7714 has no HI counterpart, but on the opposite side of NGC 7714 there is a 10**9 M(sun) HI loop 11 kpc in radius. Within the NGC 7714 disk, clumpy HI gas is observed associated with star formation regions. Redshifted HI absorption is detected towards the starburst nucleus. We compare the observed morphology and gas kinematics with gas dynamical models in which a low-mass companion has an off-center prograde collision with the outer disk of a larger galaxy. These simulations suggest that the bridge in NGC 7714/7715 is a hybrid between bridges seen in systems like M51 and the purely gaseous `splash' bridges found in ring galaxies like the Cartwheel. The offset between the stars and gas in the bridge may be due to dissipative cloud-cloud collisions occuring during the impact of the two gaseous disks.Comment: 31 pages, Latex, 11 figures, to be published in the July 10, 1997 issue of the Astrophysical Journa