370 research outputs found
Balls Pyramid, South Pacific [cartographic material] : from H.M.S. s. Herald & Torch 1853.
No full textEight views of Ball's Pyramid with Wheatsheaf Rock near Lord Howe Island in the Tasman Sea. Relief shown by hachures and spot heights. Depths shown by bathymetric soundings.; Signed: H.M. Denham Captain, Aug. 22/53.; In lower right margin: Balls Pyramid - Coral Sea.; Also available in an electronic version via the Internet at: http://nla.gov.au/nla.map-rm649. The Pyramid Alt. 1810 ft. -- Pyramid Peak bearing N 63°W about 1/2 mile -- Pyramid Peak bearing N 49°E 3/4 mile -- Pyramid N 49°30'E 24 miles -- Pyramid N 58°E 72 1/2 miles -- Pyramid N 87°E 9 miles -- Pyramid S 81°E 8 1/2 miles -- Pyramid bearing S 65°E 8 1/2 miles.Balls Pyramid, Coral Se
Crash Into Culvert Mangles Car; Two Injured
No full textPhotograph taken for a newspaper owned by the Oklahoma Publishing Company. Caption: "Crash Into Culvert Mangles Car; Two Injured This used to be a car. Now it`s the latest threat to the state`s new traffic record of seven days without a highway fatality. Lloyd Lamb, 27, Mustang, was critically injured in the vehicle when it struck a culvert and "bounced" 55 feet early Thursday near Wheatland, Gerald O. McVay, 22, Moore, a passenger, received a broken leg and head injuries. A car-demolishing accident on the outskirts of Wheatland early Thursday, in which one man was critically injured, threatened to crack the state`s new traffic record, entering its seventh day without a fatality. The automobile, approaching Wheatland from the east on SH41, careened out of control, struck a culvert, overturned and "bounced" 55 feet, according to highway patrol troopers. Vehicle Was Missing The vehicle was stolen an hour earlier from NW 6 and Broadway, Oklahoma City, the troopers stated. Critically hurt was Lloyd Lamb, 27, who reportedly lives south of Mustang. Another man in the car, Gerald O. McVay, 22, Moore, received a broken leg and head injuries. Both were unconscious Thursday morning. Troopers did learn immediately who was driving the automobile, ownership of which checks to Jack L. Corbett, Britton. Corbett reported the car missing. Safety Record Stretches At 11:15 p.m. Wednesday, Oklahoma completed six straight days without a traffic fatality. The last six-day period dates back to early 1947. Apparently no one is sure when the last seven-day fatality-free stretch occurred. Jerry Marx, executive secretary of the highway patrol, said records for the years preceding 1946 could be found.
Effect of laser temporal intensity skew on enhancing pair production in laser - electron-beam collisions
No full textRecent high-intensity laser experiments (Cole et al 2018 Phys. Rev. X 8 011020; Poder et al 2018 Phys. Rev. X 8 031004) have shown evidence of strong radiation reaction in the quantum regime. Experimental evidence of quantum effects on radiation reaction and electron-positron pair cascades has, however, proven challenging to obtain and crucially depends on maximising the quantum parameter of the electron (defined as the ratio of the electric field it feels in its rest frame to the Schwinger field). The quantum parameter can be suppressed as the electrons lose energy by radiation reaction as they traverse the initial rise in the laser intensity. As a result the shape of the intensity temporal envelope becomes important in enhancing quantum radiation reaction effects and pair cascades. Here we show that a realistic laser pulse with a faster rise time on the leading edge, achieved by skewing the temporal envelope, results in curtailing of pair yields as the peak power is reduced. We find a reduction in pair yields by orders of magnitude in contrast to only small reductions reported previously in large-scale particle-in-cell code simulations (Hojbota et al 2018 Plasma Phys. Control. Fusion 60 064004). Maximum pairs per electron are found in colliding 1.5 GeV electrons with a laser wakefield produced envelope 7.90 × 10-2 followed by a short 50 fs Gaussian envelope, 1.90 × 10-2, while it is reduced to 8.90 × 10-5, a factor of 100, for an asymmetric envelope
Eficacia de la rehabilitación hidrológica para mejorar el hábitat de peces y mangles en cispata, Caribe colombiano: una estrategia de adaptación al cambio climático
No full textEl objetivo de este estudio fue evaluar la eficacia de la rehabilitación hidrológica (RH) implementada en el sector Dago-Ustria, para mejorar en el corto plazo (<6 meses) el servicio de hábitat de peces y mangles, como estrategia de adaptación al cambio climático basada en ecosistema (AbE). Se midieron parámetros de calidad del agua superficial, comunidad íctica y regeneración natural del manglar antes y después de dos y cinco meses de la RH. En el corto plazo, la RH mejoró significativamente las condiciones fisicoquímicas del hábitat para peces y mangles. Si bien, las respuestas de la comunidad íctica y de la densidad de plántulas de mangles en el tiempo de esta investigación fueron diferentes en las zonas intervenidas y monitoreadas, no fueron significativas; por lo tanto, se requiere mayor tiempo de monitoreo para evidenciar contundentemente el efecto del mejoramiento de la calidad del agua en caños y ciénagas y dentro del manglar. Las variables de calidad de agua, regeneración natural y comunidad íctica medidos en esta investigación se consideran eficientes indicadores para el monitoreo del éxito de la RH en Cispata, por la facilidad y bajo costo de los métodos y la participación comunitaria. La información generada en este estudio puede aplicarse en la gestión de manglares y su planificación, como una medida de AbE bajo un escenario de cambio climático.The aim of this study was to evaluate the efficacy of the hydrological rehabilitation (HR) implemented in the Dago-Ustria sector, to improve in the short term (<6 months) fish and mangrove habitat, as a climate change adaptation strategy based on ecosystems (EbA). Parameters of surface water quality, fish community and natural regeneration of the mangrove were measured before and after two and five months of HR. In the short term, HR significantly improved the physicochemical conditions of the habitat for fish and mangroves. Although the responses of the fish community and the density of mangrove seedlings at the time of this research were different in the intervened and monitored areas, they were not significant, therefore, longer monitoring time is required to clearly demonstrate the effect of the improvement of the water quality in channels and marsh and within the mangroves. The variables of water quality, natural regeneration, and fish community measured in this study are considered efficient for monitoring the success of HR in Cispata, due to the ease and low cost of the methods and community participation. The information generated in this study can be applied in mangrove management and their planning, as a measure of EbA under a climate change scenario
Energetic Radiation from Wakefield Acceleration and its Applications
No full textThe driving theme of this thesis is the experimental production and characterisation of high-energy gamma radiation using a laser wakefield accelerator (LWFA), and its application in the context of studies of fundamental QED phenomena.
An electron beam from shock injection of an energy up to 1.3 GeV was collided with a laser pulse at an intensity of a0 ~ 0.2 - 1 producing 10's of MeV photons from linear inverse Compton scattering (ICS). The emitted radiation was used to diagnose the properties of the electron beam and of the laser pulse at the interaction. It was demonstrated that this can also be used to systematically facilitate the spatio-temporal overlap of the electron beam and the laser pulse in future radiation reaction studies.
A relativistic electron beam of energy > 500 MeV was collided with a tightly focused laser pulse with a0 ~ 10. The interaction generated broadband synchrotron-like radiation from non-linear inverse Compton scattering (ICS) with critical energies > 30 MeV, which are the highest ICS photon energies reported from an all-optical setup at this time. The high photon energies in turn enabled a significant measurement of energy loss in the electron beam, rendering this the first published measurement of radiation reaction in an LWFA setup.
An electron beam from LWFA was used to commission a bremsstrahlung gamma-ray source reaching photon energies of several hundreds of MeV. Different materials and accelerator configurations were used to optimise the yield of photons and to mitigate the production of secondary particles.
The energetic gamma rays were then collided with the X-ray field emitted by a hot plasma in order to attempt the production of electron-positron pairs from the Breit-Wheeler process.Open Acces
Variations in abundance, feeding patterns and prey availability of post-settlement King George whiting, Sillaginodes punctata, in nearshore marine waters
No full textSpatial variation in the recruitment of Sillagi,nodes punctata into five sheltered unvegetated sites in south-western Australia was determined through fortnightly sampling of post-settlement individuals, using a fine-mesh seine net, during the recruitment period (between early September and early December). The diets of these recruits were examined to determine whether there were spatial, temporal and ontogenetic variations in dietary composition. In addition, the invertebrates which constituted important prey for post-settlement S. punctata were sampled at the same locations using sediment corers and sweep nets to establish spatial patterns in prey abundance. These spatial patterns in abundance of prey were compared with the abundance and dietary composition of post-settlement S. punctata. Particulate organic matter and microphytobenthos were also sampled using cores to establish whether the spatial patterns in abundance of invertebrate prey were associated with the distribution of these plant materials.
Densities of post-settlement S. punctata differed significantly among sites, being highest at Mangles Bay, thus demonstrating that the recruitment of S. punctata into unvegetated habitats in nearshore marine waters varied on a spatial scale. At sites with lower densities of fish, S. punctata were present throughout the recruitment period at Point Peron and Safety Bay, whilst they were only present in the first half of the recruitment period at the other two sites. This result suggests the possibility of movement or mortality of recruits at these sites.
The overall diet of post-settlement S. punctata at the study sites was dominated by crustaceans, comprising cyclopoid, calanoid or harpacticoid copepods or gammarid amphipods. The dietary composition of post-settlement S. punctata varied spatially suggesting fish were feeding opportunistically. Fish at Mangles Bay consumed harpacticoid and calanoid copepods frequently and in large proportions, whilst those at Point Peron and Safety Bay consumed gammarid amphipods :frequently in large proportions. At Woodman Point and Rockingham, sites in which only small individuals were captured in the initial stages of sampling, the overall diet was dominated by cyclopoid copepods. Ordinations emphasised that the dietary composition of fish at Mangles Bay was distinct from that at other sites, primarily due to high proportions of harpacticoid and calanoid copepods in the diet of fish at this site and to high proportions of cyclopoid copepods and gammarid amphipods in the early and late stages of sampling, respectively, at the other sites.
With increasing size, post-settlement S. punctata at Mangles Bay consumed smaller proportions of harpacticoid copepods and larger proportions of calanoid copepods, while those at Safety Bay consumed lower proportions of cyclopoid copepods and increasing proportions of gammarid amphipods. The dietary composition of S. punctata caught from different sites exhibited temporal variation during the sampling period with respect to the proportions of the main prey types consumed. This temporal pattern was not consistent with size-related changes in dietary composition at Mangles Bay, where the diets of similar-sized fish varied with respect to the sampling occasion on which they were collected.
The densities of prey commonly consumed by S. punctata exhibited marked spatial variation, with densities ofharpacticoid and calanoid copepods being highest at Mangles Bay, and those of gammarid amphipods being highest at Point Peron and Safety Bay. Incidentally, the high densities of post-settlement S. punctata that were characteristic of Mangles Bay, coincided with high densities of harpacticoid and calanoid copepods. Furthermore, the low densities of fish that were recorded at Point Peron and Safety Bay throughout the sampling period, coincided with high densities of amphipods. At the sites where individuals were present only in the early phase of sampling, i.e. Woodman Point and Rockingham, low densities of all three prey commonly consumed by S. punctata were found.
Spatial variation in dietary composition of S. punctata was associated with that of the abundance of commonly consumed prey. Sillaginodes punctata at Mangles Bay consumed harpacticoid and calanoid copepods more frequently and in larger proportions to fish from the other sites and these prey were most abundant at this site. Similarly, S. punctata at Point Peron and Safety Bay, where amphipods were most abundant, consumed amphipods more frequently and in larger proportions to fish from Mangles Bay. The spatial patterns in abundance of prey were not associated with the mass of particulate organic matter or microphytobenthos, which were similar at all sites, except in the case of particulate organic matter, where Point Peron had slightly higher mass. In addition, a preliminary investigation of the stable isotopes, 13C/12C and 15N/14N, revealed that these sources of primary production were unlikely to be primary sources of carbon to this food chain. More likely sources could include rhodophytes and phaeophytes
ESTUDIO PILOTO PARA EL AISLAMIENTO DE VIBRIO SPP EN OSTRAS (CRASSOSTREA RHIZOPHORAE) CAPTURADAS EN LA CIÉNAGA DE LA VIRGEN, CARTAGENA, COLOMBIA
No full textEn Cartagena de Indias, las ostras son consideradas productos marinos de gran importancia económica y social, por el impacto que representan en el sector turístico y hotelero. Sin embargo, han sido señalados como posibles vectores significativos de toxi - infecciones alimentarias. Determinar la contaminación por Vibrio en Ostras (Crassostrea rhizophorae) capturadas en la Ciénaga de la Virgen, con el fin de alertar a las entidades encargadas de proteger la salud del consumidor en Cartagena. Entre Febrero y Abril del 2006, fueron analizadas 67 Ostras pertenecientes a los 5 puntos estratégicos a lo largo de la Ciénaga de la Virgen: Pantalla metálica, Mangles sector cielo mar, Espolones, Mangles sector aeropuerto y Mangles sector oriental. El aislamiento e identificación de Vibriose realizó mediante cultivo y pruebas bioquímicas. Las especies de Vibrios predominantes fueron V. alginolyticus(23%), V fluvialis (20%), V. parahaemolyticus (10%), V. carchariae y V mimicus (13%), V. vulnificus, cincimatiensis y V. campbelli (7%). El punto de muestreo con mayor número de Vibrios aislados fue Mangles sector cielo mar con un 30% del total de especies encontradas. Estadísticamente no hubo diferencias significativas entre los puntos, debido a su distribución porcentual homogénea. La ausencia de Vibrio cholerae en este estudio, podría estar asociada con la falta de serotipos halófilos, por lo que su crecimiento sería inhibido por la alta salinidad en los lugares de captura. Los factores que influyen en la proliferación de otras especies de Vibrios en Ostras, pueden estar relacionados con las características de la Ciénaga. Abstract Oysters are considered a see fruit or major economical and social importance in Cartagena de Indias, due to the impact that they have in the hotel and tourism industry. However, oysters have been hold responsible as possible significant vectors for food poisoning. to test oysters (Crassostrea rhizophorae) capture in la Ciénaga de la Virgen for contamination with Vibrio, in order to put the appropriated local costumer health care authorities, under alert. 67 Oysters, belonging to 5 strategic points through the Ciénaga de la Virgen (Pantalla metálica, Mangles cielo mar sector, Espolones, Mangles airport sector y Mangles oriental sector) were analyzed, between February and April 2006. Culture mediums and Biochemical test was used for Vibrio´s isolation and identification. the predominantVibrio´s species were V. alginolyticus (23%), V fluvialis (20%), V. parahaemolyticus (10%), V. carchariae and Vmimicus (13%), V. vulnificus, cincimatiensis and V. campbelli (7%). The sampling point with the highest number ofVibrio isolation was Mangles, cielo mar sector, which also contributed with 30% of the total of all species isolated although the difference was of no statistical significance due to their homogenous distribution. 100% of the sampling points showed cloudy water due to the presence of organic matter in suspension and visible solid waste, Thus, Factors influencing Vibrios proliferation on oysters maybe related with the Ciénaga characteristics. Palabras clave: Ostras, Vibrio, Patógenos, Especies, Bacteria, Colombia
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